HK1111553B - Mobile communication system - Google Patents

Description

Mobile communication system

The present application is a divisional application of the following applications:

the invention name is as follows: communication mode control method, mobile communication system, base station control device, base station, and mobile communication terminal

Application date: 9/30/2003

Application No.: 03827084.6

Technical Field

The present invention relates to a mobile communication system using CDMA (Code Division Multiple Access), and more particularly, to a communication mode control method, a mobile communication system, a base station control device, a base station, and a mobile communication terminal for controlling communication mode switching according to a communication state between the base station and the mobile communication terminal.

Background

In a conventional wireless multimode data communication method, there is a method of switching between an autonomous mode for autonomously transmitting and receiving data in accordance with a data rate or the like and a scheduling mode for transmitting and receiving data in accordance with a request (scheduling) for data transmission and reception such as a communication timing permitted by a base station side (see, for example, japanese patent laid-open No. 2002-369261).

In this communication method, for example, when packet data is transmitted between a base station and a wireless device at a low data rate of about 9.6kbps, control is performed in an autonomous mode. In addition, conversely, in the case of transmitting data at a high data rate, control is performed in the scheduling mode.

Here, the scheduling mode may frequently transmit signaling used to notify the wireless device of the scheduling from the base station. Therefore, if the data amount is not transmitted more than 1 time, the transmission efficiency of the data becomes low compared to the number of signaling times.

In the above-described conventional data communication method, in the case of a high data rate in which the amount of data per unit time is large, the above-described drawback can be eliminated by performing control in the scheduling mode.

However, the above-mentioned prior art document discloses an idea of switching between the autonomous mode and the scheduling mode mainly based on the data amount in the above-mentioned conventional data communication method, but does not disclose a sufficient process for switching the communication conditions other than the above.

In the communication mode switching, if demodulation processing of a coded signal and use of data requiring real-time performance are taken into consideration, communication conditions to be used as a reference include, for example, an interference amount (hereinafter, referred to as a noise rise factor) with respect to a base station, a delay, and the like.

In the inventions disclosed in the above-mentioned prior art documents, it is not sufficiently discussed that a wireless device performing data communication not allowing delay should operate in an autonomous mode, whereas a device performing communication allowing delay can perform flexible communication mode switching according to communication conditions such as operation in a scheduling mode.

In addition, in the uplink packet communication by the CDMA method, if the interference of the transmission signal from the radio device exceeds the noise rise factor limit of the base station concerned, the transmission signal cannot be demodulated.

The noise rise factor margin also varies with interference from other cells (cells), transmissions of other wireless devices of the same cell, and so on. Therefore, in the packet communication of the CDMA method, it is necessary to pay sufficient attention to the management of the noise increase factor limit.

Here, as the management of the noise increase factor limit, if the limit of the noise increase factor limit can be sufficiently secured, the autonomous mode can be used even when the amount of data to be transmitted is large. In this case, there is an advantage that the number of times of signaling can be reduced and delay is small compared to the scheduling mode.

Thus, the noise increase factor limit of the base station can be appropriately assigned according to the traffic situation, and efficient communication can be performed according to the change in the noise increase factor.

In order to solve the above-described problems, it is an object of the present invention to provide a communication mode control method capable of switching a communication mode by properly considering factors other than a data amount and capable of performing efficient data communication in accordance with a change in a noise increase factor accompanying a change in a communication load between a base station and a mobile communication terminal.

Another object of the present invention is to provide a communication mode control method capable of allocating transmission modes between an autonomous mode and a scheduling mode according to QoS by considering QoS (quality of Service) parameters such as delay and designating a transmission mode switching threshold for each terminal.

Further, the present invention aims to provide a mobile communication system, a base station control device, a base station, and a mobile communication terminal that perform efficient data communication according to a noise increase factor that varies with changes in communication load, using the above-described method.

Disclosure of Invention

According to the communication mode control method of the present invention, when the mobile communication terminal switches between the autonomous mode in which autonomous data communication is performed with respect to the base station and the scheduling mode in which data communication is performed at the communication timing permitted by the base station, the communication mode that should be set in the mobile communication terminal is determined based on the interference amount and/or the communication characteristic thereof of each communication mode in the cell of the base station and the signal indicating the communication data amount notified by the mobile communication terminal, and the communication mode is notified from the base station to the mobile communication terminal.

This makes it possible to achieve efficient data communication in accordance with the noise increase factor that varies with changes in the communication load between the base station and the mobile terminal.

Drawings

Fig. 1 is a diagram generally showing the structure of a mobile communication system according to embodiment 1 of the present invention;

fig. 2 is a channel structure diagram showing a mobile communication system according to embodiment 1;

fig. 3A and 3B are diagrams for explaining a communication mode of wireless multi data mode communication between a terminal and a base station in a mobile communication system according to embodiment 1;

fig. 4 is a diagram for explaining a threshold value of a transmission data buffer as a reference for switching a communication mode of a mobile communication terminal according to embodiment 1;

fig. 5 is a diagram showing allowable limits of interference caused by various factors related to an uplink signal to a base station according to embodiment 1.

Fig. 6 is a diagram showing an example of assigning noise increase factor limits to an autonomous mode and a scheduling mode when a plurality of terminals in a cell use uplink packet communication;

fig. 7 is a diagram showing a case where the threshold for determining switching of the communication mode of the transmission data buffer is set low in the case shown in fig. 6;

fig. 8 is a diagram showing an example of assigning noise increase factor limits to the autonomous mode and the scheduling mode when there are few terminals using uplink packet communication in a cell;

fig. 9 is a diagram of a case where the threshold value for the communication mode switching determination of the transmission data buffer is set high in the case shown in fig. 8;

fig. 10 is a block diagram showing an internal structure of the base station in fig. 1;

fig. 11 is a block diagram showing an internal structure of the mobile communication terminal of fig. 1;

fig. 12 is a block diagram showing an internal configuration of the base station control apparatus of fig. 1;

fig. 13 is a diagram showing an example of allocation of noise rise factor limits of a base station when a transmission mode switching threshold value of a switching terminal is determined by the base station control apparatus of embodiment 1 according to the 1 st method;

fig. 14 is a diagram for explaining a change in the transmission mode switching threshold value according to the allocation representing the noise increase factor limit shown in fig. 13;

fig. 15 is a diagram showing a change procedure in a case where a transmission data buffer threshold value is changed in a first method in the mobile communication system according to embodiment 1;

FIG. 16 is a flowchart for explaining in detail the operation of step ST9 in FIG. 15;

fig. 17 is a diagram showing an example of allocation of noise increase factor limits of base stations when a transmission mode switching threshold value of a switching terminal is determined by the base station control apparatus of embodiment 1 according to the 2 nd method;

fig. 18 is a diagram for explaining the change of the transmission mode switching threshold value according to the allocation of the noise increase factor limit shown in fig. 17;

fig. 19 is a diagram showing a change procedure in the case of changing the transmission data buffer threshold value by the 2 nd method in the mobile communication system according to the embodiment 1;

FIG. 20 is a flowchart for explaining in detail the operation of step ST9b in FIG. 19;

fig. 21 is a diagram showing an allocation example of noise increase factor limits of a base station when the base station according to embodiment 1 determines a transmission mode switching threshold of a terminal according to the 3 rd method;

fig. 22 is a diagram showing a change procedure for implementing a transmission data buffer threshold change by the 3 rd method in the mobile communication system according to the embodiment 1;

fig. 23 is a flowchart for describing in detail the operation of step ST3d in fig. 22;

fig. 24 is a flowchart showing an operation in the case where the mobile communication terminal uses the method 1 for the configuration for switching the transmission mode in accordance with an instruction from the base station side;

fig. 25 is a flowchart showing an operation of the case where the mobile communication terminal uses the 2 nd method for the configuration of switching the transmission mode according to an instruction from the base station;

fig. 26 is a flowchart showing an operation in a case where the mobile communication terminal uses the 3 rd method for a configuration of switching the transmission mode according to an instruction from the base station.

Detailed Description

In the following, for a more detailed description of the present invention, the best mode for carrying out the present invention will be described with reference to the accompanying drawings.

Example 1

Fig. 1 is a diagram generally showing the configuration of a mobile communication system according to embodiment 1 of the present invention. The mobile communication system 1 is composed of a mobile communication terminal 2 used by a user, a base station control device 3, and base stations 4a and 4 b. The base station control device 3 is interposed between a network-side structure such as a public telephone network and the base stations 4a and 4b, and relays packet communication between them.

In this way, the system 1 is configured to manage the plurality of base stations 4a and 4b for the base station controller 3 on the network side. Thereby, a robust soft handover is enabled in the system 1, i.e. a radio link is maintained between the plurality of base stations 4a, 4b for one of the terminals 2.

When the mobile communication system 1 is implemented by a W-CDMA (wideband code division multiple access) method, the mobile communication terminal 2 is referred to as a UE (user equipment), the base station controller 3 is referred to as an RNC (radio network controller), and the base stations 4a and 4B are referred to as node bs.

In particular, in high-speed uplink packet communication, a specific base station may perform scheduling for data communication with respect to a certain terminal. The base station at this time is also referred to as a serving cell for distinction. Further, a specific range in which the base station includes itself to perform communication processing is referred to as a cell as a whole. In the following description, these terms are also used as appropriate.

Fig. 2 is a diagram showing a channel configuration of a mobile communication system according to embodiment 1, showing, as an example, a channel configuration of a radio zone between the base stations 4a, 4b and the terminal 2 of the W-CDMA system.

The figure is merely an example of the embodiment, and is not limited thereto. In addition, as a channel to be actually used, a plurality of control channels may be multiplexed onto 1 channel.

First, if a description is given of a channel in the downlink direction from the base stations 4a and 4b to the terminal 2, in the configuration of the cell, there are CPICH (common pilot channel) for reporting all timing references, and P-CCPCH (primary common control physical channel) as a physical channel for BCH (broadcast channel) for reporting other reporting information to the terminal 2.

On the downlink channel, there are DL-SACCH (downlink scheduling assignment control channel) for transmitting control information and notifying the position and DL-ACK/NACK-CCH (downlink ACK/NACK control channel) for notifying the success/failure of reception of the base stations 4a and 4b, which are allocated by the scheduler, as used for uplink packet communication. Further, as a common channel in the downlink direction, there is FACH (forward access channel).

Next, if description is made of uplink channels from the terminal 2 to the base stations 4a and 4b, as the use in the uplink packet communication, there are UL-SICCH (uplink scheduling information control channel) for notifying the presence or absence of transmission data of the terminal 2, UL-TFRI-CCH (uplink TFRI control channel) for notifying the base stations 4a and 4b of the modulation scheme, coding rate, and the like selected by the terminal 2, and eutch (enhanced uplink dedicated transport channel) for transmitting user data in the uplink packet communication. In addition, RACH (random access channel) is present as a common channel in the uplink direction.

Further, the channel set for communication in both the uplink and downlink directions includes DPCH (dedicated physical channel) set for communication with a specific terminal, and can be used for communication such as voice and data, and upper layer signaling. The DPCH is further divided into a DPDCH (dedicated physical data channel) for transmitting data and a DPCCH (dedicated physical control channel) for transmitting bits related to control.

Fig. 3A and 3B are diagrams for explaining a communication mode of wireless multi data mode communication between a terminal and a base station in a mobile communication system according to embodiment 1. As shown in fig. 3A, in the data transmission processing in the autonomous mode, first, an allowable rate from the base station (node B)4a, 4B to the terminal (UE)2 may be specified in advance. At this time, the UE transmits data to the node B at any time within the range of the allowable rate. If data is received from the UE, the node B transmits an acknowledgement signal (ACK/NACK) to the UE.

In autonomous mode, one round trip communication processing of data transmission and its reply is basically completed without having to specify a previously allowable rate for each packet transmission.

Therefore, the autonomous mode has advantages of less waste of signaling and less delay since the UE can freely transmit data when wanting to transmit.

On the other hand, the autonomous mode has a disadvantage that a required noise increase factor limit must be fixed with respect to an amount of interference generated when data is transmitted, in order to enable transmission at an arbitrary timing.

On the other hand, in the data transmission processing in the scheduling mode, as shown in fig. 3B, first, information such as the UE buffer status is transmitted from the UE to the node B. Upon receiving the information, the node B performs scheduling of uplink packets among a plurality of UEs and allocates a time (subframe) allowed for transmission and a transmission rate to the UE that should recognize data transmission. In the UE, packets are sent to the node B according to their allocation and acknowledgement signals are obtained from the node B.

The scheduling mode has an advantage in that since there is no data transmission from UEs not allocated by the scheduler, it is not necessary to set a noise increase factor limit in particular.

On the other hand, as a disadvantage thereof, it requires at least two round trip communication processes consisting of a communication process and a transmission process of data itself, which are required for scheduling, and thus inevitably causes a delay.

In addition, since scheduling for notifying the node B of the presence or absence of data transmission by the UE must be performed in advance, there is a case where efficiency becomes low when the amount of data to be transmitted is small relative to the number of times of signaling.

In the autonomous mode, since transmission timing specification from the base station is not required, the terminal can autonomously determine the transmission timing. In contrast, in the scheduling mode, the base station designates transmission timing to the terminal, and the terminal transmits data according to the transmission timing.

In addition, in the scheduling mode, there is also a case where a data rate is specified by the base station. For example, in the autonomous mode, the base station may designate a transmission data rate for data transmission to the terminal, but in the scheduling mode, the base station may designate a transmission timing and a transmission data rate to the terminal and control data transmission from the terminal.

Fig. 4 is a diagram describing a threshold value of a transmission data buffer as a reference for switching a communication mode of a mobile communication terminal according to embodiment 1. Here, the mobile communication terminal 2 operates in the autonomous mode when transmission data is accumulated in a capacity equal to or smaller than the threshold of the transmission data buffer, and shifts to the scheduling mode to operate if transmission data exceeding the threshold capacity is accumulated.

In this way, the terminal 2 can switch between the autonomous mode and the scheduling mode with reference to the threshold value of the transmission data stored in the transmission data buffer. The determination of the threshold is described later.

Fig. 5 is a diagram showing tolerance limits with respect to an amount of interference (hereinafter, referred to as a noise increase factor) caused by various factors of an uplink signal to a base station according to embodiment 1. In general, in a CDMA system, a certain level of interference is tolerable with respect to a received coded signal, but when a tolerable limit of a noise increase factor limit is exceeded, the amount of interference becomes a value larger than that of the signal, and the signal cannot be correctly demodulated even by despreading.

Therefore, how to control the ideal interference amount within a range from 0 (the bottom limit of the noise increase factor) to the interference tolerance limit amount that can demodulate the received signal is important for ensuring the capacity (the number of terminals received by the base station).

As shown in the figure, among the noise increase factors at the base station side, the noise increase factors due to the scheduling mode and autonomous mode transmission can be controlled within the scheduling mode limit and autonomous mode limit by appropriately switching their transmission modes in the uplink packet communication.

On the other hand, the noise increase factor due to factors other than the scheduling mode and the autonomous mode cannot be controlled within the tolerance of the uplink packet communication.

As such interference factors, there are, for example, own-cell interference from terminals in the own cell which is approximately the sum of required signal powers, other-cell interference from interference of signals of terminals in areas covered by other base stations, thermal noise generated by a receiver in the base station, and the like.

Therefore, in order to effectively use radio resources for uplink packet communication, it is necessary to know how to adjust the range of the noise increase factor by controlling the scheduling mode limit and the autonomous mode limit.

Fig. 6 is a diagram showing an example in which, when a plurality of terminals use uplink packet communication in a cell, a noise rise factor limit (an allowable amount of interference) of a base station is assigned to an autonomous mode and a scheduling mode. In the illustrated example, a case where the number of terminals accommodated in a cell is larger than that in the case of fig. 8 described later is shown.

Although detailed description will be made later, in the base station according to embodiment 1, the base station control device 3 may set a limit of a certain range obtained by considering a QoS parameter such as delay as a controllable noise increase factor limit shown in fig. 5. In the noise increase factor limit, when the noise increase factor due to the autonomous mode is subjected to the tolerance limit, it is preferable to set a larger number of noise increase factor limits for each terminal in the cell.

In this case, since the noise increase factor limit is set within a certain range as a whole, it is necessary to reduce the allowable limit (hatched portion) with respect to the noise increase factor limit by the scheduling mode by setting the noise increase factor limit for each terminal in large amounts as shown in fig. 6.

Thus, in the case shown in fig. 6(a), if the number of terminals communicating in the scheduling mode in the cell becomes large, there is a possibility that the noise increase factor caused thereby cannot be controlled within the allowable limit.

On the contrary, if the noise increase factor limit for uplink packet communication for each terminal in the cell is set to be small, as shown in fig. 6(b), the base station can secure a larger allowable limit (hatched portion) for the noise increase factor due to the scheduling pattern.

That is, when the number of terminals communicating in the scheduling mode in a cell is large, it is necessary to reduce the allowable limit for each terminal as much as possible with respect to the noise increase factor due to the autonomous mode.

In the uplink packet communication, if the amount of transmission data decreases at a burst, the transmission rate also decreases. In this case, in order to reduce the transmission power required for data transmission, the noise increase factor associated with the base station reception signal is also reduced.

Therefore, as shown in fig. 6(b), in order to reduce the allowable limit for each terminal as much as possible, it is preferable that the noise increase factor itself due to the autonomous mode is reduced, that is, it is preferable that the noise increase factor itself due to the autonomous mode is controlled so as to perform communication at a low data rate by the autonomous mode.

Specifically, when the number of terminals accommodated in a cell is large, as shown in fig. 7, by setting a threshold for determining switching of the communication mode of the transmission data buffer of each terminal to be low, if the threshold exceeds a low data rate range in which the amount of transmission data is small, it is desirable to switch from the autonomous mode to the scheduling mode.

Next, as shown in fig. 8, a case where there are few terminals using uplink packet communication in a cell (7 in fig. 6 and 2 in fig. 8) is considered. In this case, even if the noise increase factor limit for each terminal is set to be large in the base station, as shown in fig. 8a, a sufficient margin (hatched portion) for the noise increase factor due to the scheduling pattern can be secured.

As shown in fig. 8(b), even if the noise rise factor limit for each terminal is set to be small in the base station, the allowable limit of the noise rise factor with respect to the scheduling pattern is almost the same as that in fig. 8 (a).

That is, in the case where the number of terminals accommodated in the cell is small, communication at a high data rate can still be performed in the autonomous mode as compared with the case of fig. 6.

Specifically, when the number of terminals that can be accommodated in a cell is small, as shown in fig. 9, a large amount of data can be handled by setting the threshold for determining the communication mode switching of the transmission data buffer of each terminal to be high and allowing a high data rate even in the autonomous mode.

As described above, according to the traffic status of communication between the terminal and the base station, for example, the number of terminals operating in the scheduling mode in the cell and the operating state thereof, and the scheduler operating in the autonomous mode and the operating state thereof, the threshold value of the transmission data buffer in the terminal can be appropriately changed, and high-quality communication with less interference can be expected.

In addition, considering that the autonomous mode has a communication characteristic in which the transmission delay is small, when there is a margin within an allowable limit of the assigned noise increase factor, it is desirable that the terminal having a strict requirement for delay performs communication in the autonomous mode as much as possible.

Fig. 10 is a block diagram showing an internal structure of the base station of fig. 1, and the basic operation of the base station is described through the figure. In fig. 10, in order to prevent the description from being complicated, the names of the components described later are described by simplified names, and the same reference numerals denote the same components.

First, a process common to general CDMA modulation and demodulation will be described.

If the transmission operation is described, the modulation unit 5 in the base station 4a, 4b multiplies the signals of the respective channels (P-CCPCH, downlink DPDCH, FACH, CPICH, DL-SACCH, DL-ACK/NACK-CCH, downlink DPCCH, etc.) by the channelization code generated in the downlink channelization code generator 6, and multiplexes the signals.

Next, the modulation section 5 multiplies the multiplexed signal of each channel by the scrambling code generated in the downlink scrambling code generator 7, and performs a spreading process.

The baseband signals, which are the respective channel signals multiplexed in the modulation section 5, are output to the frequency conversion section 8. The frequency conversion unit 8 converts the baseband signal to a carrier frequency, and outputs the converted signal to the power amplification unit 9. In the power amplifying section 9, the signal inputted from the frequency converting section 8 is amplified to a desired power in the internal power amplifier. The signal amplified in the power amplification unit 9 is transmitted to the terminal 2 side through the antenna 10.

Here, if the pilot signal generator 27 obtains a clock signal as a reference from the timing management unit 26, the terminal 2 sets a pilot signal used as a reference for demodulation processing in the CPICH and transmits the pilot signal throughout the entire cell.

Next, if a description is given of the receiving operation, a weak signal received from the antenna 10 is input to the low-noise amplification unit 11. The low-noise amplification unit 11 amplifies the signal and outputs the amplified signal to the frequency conversion unit 12. Frequency conversion section 12 converts the signal inputted from low-noise amplification section 11 to the frequency of the baseband signal.

The despreader 15 performs despreading processing on the baseband signal frequency-converted by the frequency conversion unit 12 by multiplying the scrambling code generated in the scrambling code generator 13, and extracts a signal component of each terminal. The demodulation unit 30 separates signals of respective channels from the despread signal input from the despreader 15 by means of the channelization code generated in the upstream channelization code generator 14.

Next, an operation of obtaining power of the signal and the interference is described.

First, the desired radio wave power measuring unit 16 obtains the power of the desired radio wave from the pilot signal of the uplink DPCCH from the despreader 15. On the other hand, low-noise amplifier 11 obtains all the received power of the desired radio wave and noise by antenna 10.

The interference radio wave power measuring unit 17 obtains the interference radio wave power as a noise component by subtracting the power of the desired radio wave obtained by the desired radio wave power measuring unit 16 from all the received powers input via the low-noise amplifying unit 11, the frequency converting unit 12, and the despreader 15.

Then, the power of the desired radio wave and the power of the interfering radio wave are transmitted from the measurement units 16 and 17 to the uplink packet transmission management unit 24, respectively. In this manner, the uplink packet transmission management unit 24 obtains the power of the desired signal from each terminal in the own cell.

Further, the uplink packet transmission management unit (communication management unit) 24 obtains the own-cell interference, other-cell interference, and an interference component due to thermal noise (noise increase factor) related to the uplink packet communication from the base station control apparatus 3.

Here, interference other than the interference component of the own cell (interference and thermal noise of other cells) cannot separate noise and signals because the code is unknown. Therefore, the uplink packet transmission management unit 24 obtains, from the base station control device 3, an interference component other than the own-cell interference component, which is an interference component power obtained by mixing noise such as thermal noise with interference from another cell. Although the interference component cannot be distinguished from interference of another cell or thermal noise, it is not particularly necessary to distinguish the interference component from control processing of the amount of interference.

Next, the uplink packet transmission managing unit 24 obtains the interference of another cell from an allowable limit within a certain range based on the congestion limit, and obtains a noise increase factor limit that can be controlled by the uplink packet communication by performing allowable limit compensation on the interference component of the mixed noise such as the interference of another cell and the thermal noise.

The congestion limit is an index representing the maximum allowable capacity (number of terminals), which is defined as the ratio J/S of the harmful component power J to the signal power S. The capacity (number of terminals) in a cell can be determined based on the congestion limits.

The capacity indicates not only a terminal to be communicated with a certain base station at this time but also whether or not the number of terminals can be accommodated in the base station cell.

The congestion limit can be calculated by a radio resource management unit in the base station control apparatus 3 described later, for example, according to the following relational expression.

First, assuming that the received signal power of the base station is s (w) and the transmission rate of the communication data is R (bit/s), the power Eb of the signal per bit can be expressed by the following equation (1).

Eb＝S/R ...(1)

Here, S is the power of the signal from the mobile terminal 2 received by the base station, and is assumed to be receivable at an equalized level in the base station by a high-speed power control function (inner loop) by a TPC command based on CDMA. In addition, in W-CDMA, S can be obtained by the strength of the pilot signal, and R can be obtained by the indication of TFCI or the like.

Hereinafter, the power io (w) of the interference component from other terminals in the local cell can be expressed by, for example, the following equation (2).

However, N (number) is the maximum number of terminals in the own cell, and may be considered as a terminal other than the own terminal. Si is the signal power received by the base station from terminal 2 from 1 st to (N-1) th, and index i is a positive integer from 1 to (N-1). In addition, Ri is a transmission speed (bit/sec) of communication data by the 1 st to (N-1) th terminals 2.

Thus, Io can be expressed as the sum of the respective signal powers of the number of terminals obtained by subtracting 1 from the maximum number of terminals N. In the above equation (2), the signal power and the transmission rate of each terminal 2 are assumed to be equal to S and R, respectively.

Since it is inconvenient to operate by discriminating noise of each frequency band range, interference components from other-cell interference and thermal noise may not be discriminated as above, and may operate as an average noise power spectral density no (w) converted into noise energy per 1 Hz.

If the spectrum bandwidth of the spread spectrum signal is w (hz) and the power of the narrow-band unwanted noise is j (w), then the noise increase factor (interference amount) (No + Io) caused by the interference of the present cell, the interference of other cells and the thermal noise can be expressed by the following formula.

No+Io＝J/W ...(3)

Here, SIR (signal to interference ratio) can be obtained from the ratio Eb/(No + Io) of the energy Eb per bit signal and the sum of noise increase factors caused by thermal noise and other cell interference and own cell interference.

The SIR can be expressed as equation (4) using the above equation (1) and equation (3) as follows.

Eb/(No+Io)＝S·W/(J·R) ...(4)

By modifying the above equation (4), if the congestion limit (congestion limit) J/S of the limit that can be demodulated in CDMA is to be calculated, it becomes the following equation (5).

J/S＝(W/R)/{Eb/(No+Io)} ....(5)

The base station control device 3 calculates an allowable limit (a limit to the interference limit by the congestion limit in consideration of the operation state of the other cell and the traffic state of the target base station cell, and the QoS parameter such as delay) for keeping the limit to the interference further within a predetermined range from the congestion limit, by taking into account the operation state of the other cell and the traffic state of the target base station cell managed by itself, and notifies the target base station of the calculated allowable limit.

In the target base station, the noise increase factor control is executed by switching the communication mode within the range of the allowable limit notified by the base station control device 3.

In this way, the base station receives the influence of the own communication according to the operation state of the cell other than the base station, and even if the control is performed, the interference amount of the received signal can be prevented from exceeding the congestion limit of the demodulation limit. As will be described in detail later.

The uplink packet transmission management unit 24 of the target base station uses, as the noise increase factor limit that can be controlled as shown in fig. 5, the limit obtained by subtracting the allowable limit (the non-control limit shown in fig. 5) of the noise increase factor due to the thermal noise, the other-cell interference, and the interference of the own cell from the allowable limit in the above-described certain range.

In addition, if the signal power from the terminal in the cell is defined as S and the harmful power J (w) is assumed to be caused by interference from terminals other than the target terminal, the power J can be expressed as the following equation (6).

J＝(N-1)S ...(6)

The following equation (7) can be derived from the above equation (5) and equation (6).

(N-1)＝(W/R)/{Eb/(No+Io)} ....(7)

In the above equation (7), (N-1) corresponds to the maximum number of terminals that can be accommodated in the own cell except for the target terminal. Here, if the transmission speed of the communication data increases, the congestion margin according to equation (5) decreases, and the amount of accommodation of the terminal in the own cell according to equation (7) also becomes smaller.

In addition, when the SIR between the target terminal and the base station increases, for example, in order to secure a required BER (bit error rate), even when the base station requests the target terminal with stronger transmission power, the congestion limit is reduced according to the above equation (5).

Returning to the description of the operation of the base station, the channel quality measuring unit 18 calculates a signal-to-interference ratio (SIR) using the desired electric wave and the interference wave power input by the desired electric wave power measuring unit 16 and the interference electric wave power measuring unit 17, respectively, and the powers of interference components caused by the interference of the own cell, the interference of other cells, and the thermal noise obtained by the base station controller 3, and outputs to the quality target comparing unit 19.

In the W-CDMA scheme, terminal transmission power control called an outer loop is performed based on a target SIR value. The target SIR value may be set in advance in the quality target comparing unit 19.

The coding unit 22 in the base station counts the block error rate (BLER) for communication between target terminals by CRC (cyclic redundancy check) error, and if the required BLER is not satisfied, performs a change setting of the target SIR value of the improvement-quality target comparing unit 19. This is called outer loop power control.

On the other hand, the quality target comparing unit 19 compares the signal-to-interference ratio (SIR) calculated by the channel quality measuring unit 18 with a target signal-to-interference ratio (target SIR value), and notifies the TPC generating unit 20 of the comparison result.

When the TPC generation section 20 determines that the desired signal power of the received signal is weaker than the target signal based on the comparison result, an instruction to increase the transmission power of the TPC (transmission power command) called an inner loop is set in the downlink DPCCH, and the instruction is output to the modulation section 5.

The downlink DPCCH signal from the TPC generation unit 20 is transmitted to the terminal 2 via the modulation unit 5, the frequency conversion unit 8, the power amplification unit 9, and the antenna 10, as described above.

In contrast, if it is judged that the power of the desired signal is stronger than the target signal based on the comparison result of the quality target comparing unit 19, the TPC generation unit 20 sets an instruction for lowering the transmission power on the downlink DPCCH as TPC output to the modulation unit 5. The subsequent processing is the same. This power control is called inner loop power control.

In a CDMA system, the strength of a signal being increased must interfere with other signals. Therefore, the transmission and reception signals must perform the above-described processing and be controlled with sufficient signal power.

Next, a structure required in the uplink packet communication will be described.

First, the operation of the autonomous mode is described.

In autonomous mode operation, the base stations 4a, 4b transmit the allowed transmission limits to the terminal 2 beforehand using the DL-SACCH or the same downlink signalling channel. The transmission tolerance limit is information for specifying a communication condition required for the base station to demodulate a signal transmitted by the terminal 2 in the autonomous mode uplink packet. E.g., maximum data rate allowed, etc.

Thereafter, if a signal is received from the terminal 2, the demodulation unit 30 separates signals of respective channels from the received signal according to the operation of the receiving side described above.

The TFRI reception unit 21 receives, among the channel signals separated by the demodulation unit 30, a signal for setting UL-TFRI-CCH including the modulation parameter and the TFRI (transport format resource indicator) of the transport format selected by the terminal 2.

TFRI reception section 21 extracts demodulation parameters of eutch from the UL-TFRI-CCH signal, and sets them in demodulation section 30 and decoding section 22. The demodulation unit 30 demodulates the data itself from the terminal 2 in the EUDTCH using the EUDTCH demodulation parameter, and outputs to the decoding unit 22. In the decoding unit 22, the data itself from the terminal 2 in the EUDTCH is demodulated using the EUDTCH demodulation parameter.

The response signal generating unit 23 uses the demodulation result of the decoding unit 22 to determine whether or not the packet data transmitted by the terminal 2 can be correctly received at the base stations 4a and 4 b.

Here, when the reception can be correctly performed, the response signal generation unit 23 generates ACK for notifying the reception success and sets the ACK in DL-ACK/NACK-CCH, thereby notifying the terminal 2 of the transmission operation. In contrast, when there is an error in the data from the terminal 2, the response signal generation unit 23 also notifies the terminal 2 by generating NACK for notifying reception failure.

Next, the operation of the scheduling mode is described.

In the operation in the scheduling mode, transmission buffer amount receiving section 31 receives the UL-SICH signal from demodulation section 30, acquires information related to transmission data in scheduling mode terminal 2, and notifies it to uplink packet transmission management section 24.

The uplink packet transmission managing section 24 obtains the timing of the sub-frame from the timing managing section 26, and determines the packet transmission timing by comprehensively judging the amount of data held in the transmission data buffer of each terminal in the own cell, the transmission power limit of the terminal, and the like.

The transmission rate/timing specification information transmitting unit 25 is notified of the transmission timing of the packet determined by the uplink packet transmission managing unit 24. In the transmission rate/timing specification information transmission unit 25, a subframe and a transmission rate which are allowed to be transmitted are set in DL-SACCH, and transmitted to the terminal 2 according to the transmission operation.

Thereafter, if a signal is received from the above-mentioned terminal 2, the demodulation unit 30 separates signals of the respective channels from the received signal according to the above-mentioned operation of the receiving side.

The TFRI reception unit 21 receives, from the respective channel signals separated by the demodulation unit 30, the UL-TFRI-CCH signal indicating the TFRI of the subframe where transmission is permitted and set by the terminal 2.

Next, TFRI receiving section 21 extracts the eutch demodulation parameters from the UL-TFRI-CCH signal, and sets them in demodulation section 30 and decoding section 22. The demodulation unit 30 demodulates the data itself from the terminal 2 relating to the EUDTCH using the EUDTCH demodulation parameter, and outputs the data to the decoding unit 22. In the decoding unit 22, the data itself from the terminal 2 relating to the EUDTCH is demodulated using the EUDTCH demodulation parameter.

When the base station can correctly receive the packet transmitted by the terminal 2, the response signal generating unit 23 generates ACK as described above, generates NACK in the case of an error, and notifies the terminal 2 by setting this in DL-ACK/NACK-CCH.

Next, a configuration in which signaling for changing the threshold value relating to switching of the transmission data buffer communication mode is performed will be described.

First, when the above threshold change is notified (signaled) to the terminal 2 in the own cell together, the uplink packet transmission management unit 24 in the base station determines the change in consideration of the traffic status in the own cell, and notifies the base station control device 3 of the change.

The base station control apparatus 3 generates information on the threshold value (information on how to change the threshold value and the like) in consideration of the operation state of a base station other than the base station to which the notification is made, inserts the information into the report information, and transmits the report information to the base station.

The report information transmitter unit 28 in the base station receives a set of report information in which information relating to the scheduling is inserted from the base station controller 3, sets the report information in the P-ccpch (bch), and transmits the report information to the terminal 2 in accordance with the transmission operation. The report information may be set in another channel.

When each terminal 2 specifies the threshold value, the uplink packet transmission management unit 24 in the base station accommodating the terminal 2 in the cell determines the change in the traffic status in accordance with the communication with the terminal 2, and notifies the base station control device 3 of the change.

The base station control device 3 generates information on the threshold value (information on how to change the threshold value and the like) in consideration of the operation state of other base stations other than the base station which has issued the notification, and sets the information on the individual channel to be transmitted to the base station as a message.

In the downlink channel transmitting unit 29 in the base station, if the message related to the threshold is obtained from each channel, the message is set on the downlink dpdch (dpch), and is transmitted to the terminal 2 whose threshold should be changed according to the transmission operation. If there is a response message to the contrary, the response message is received by the channel receiving unit 32 on the uplink.

In addition, when the individual channel is released during communication with the terminal 2, the information on the threshold value may be set on the common channel.

In the base station control device 3, if it is determined that the respective channels are released based on the radio resource management information, information on the threshold is set on the common channel and transmitted to the base station as a message.

If a message related to the threshold is obtained from the common channel, the downlink common channel transmitter unit 34 in the base station sets the message in the FACH and transmits the message to the terminal 2 whose threshold should be changed according to the transmission operation. If there is a response message to the contrary, the uplink common channel receiving unit 33 receives the response message.

In the above description, the configuration in which the base station side determines the change of the threshold value has been described, but the base station side may specify the transmission mode itself set in the terminal 2.

In this case, since there is no information on the threshold value in the signaling operation for changing the threshold value, it is necessary to transmit information for specifying the transmission mode to be set in the terminal 2 to the terminal 2. A detailed description of this process is described later.

Fig. 11 is a block diagram showing an internal structure of the mobile communication terminal of fig. 1, and a basic operation of the mobile communication terminal will be described through the same. In fig. 11, in order to prevent the cumbersome description, the names of the constituent elements described later are described by simplified names, and the same reference numerals denote the same constituent elements.

First, a process common to general CDMA modulation and demodulation will be described.

Describing the transmission operation, the modulation unit 35 multiplies the signals of the respective channels (UL-SICCH, UL-TFRI-CCH, FACH, uplink DPCH, etc.) by the channelization code generated in the uplink channelization code generator 36, and then multiplexes the signals. Next, the modulation section 35 multiplies the signal multiplexed with each channel signal by the scrambling code generated by the uplink scrambling code generator 37, and performs a spreading process.

The baseband signal, which is the signal of each channel multiplexed by the modulation section 5, is output to the frequency conversion section 38. The frequency conversion unit 38 converts the baseband signal to a transmission frequency, and outputs the converted signal to the power amplification unit 39.

In the power amplifying unit 39, the signal input from the frequency converting unit 38 is amplified to a required power from an internal power amplifier. The signal amplified by the power amplification unit 39 is transmitted to the base stations 4a and 4b via the antenna 40.

Next, describing the receiving operation, a weak signal received through the antenna 40 is input to the low noise amplifier 41. The low noise amplifier 41 amplifies the signal and outputs the signal to the frequency conversion unit 42. The frequency conversion section 42 converts the signal inputted from the low noise amplifier 41 to the frequency of the baseband signal.

The despreading demodulation unit 46 multiplies the baseband signal frequency-converted by the frequency conversion unit 42 by the scrambling code generated by the downlink scrambling code generator 45, performs despreading processing, and separates signals of respective channels by the channelization code generated by the following channelization code generator 44.

Thereafter, the despreading demodulator 46 outputs the TPC command in the signal received from the base station to the power control unit 43. The power control unit 43 instructs the power amplification unit 39 to increase or decrease the transmission power in accordance with the TPC command, and sets the transmission power by the power amplification unit 39 in accordance with the instruction.

Further, the CPICH signal among the channel signals separated by the despreading demodulation unit 46 is received by the common pilot signal reception unit 47.

The common pilot signal receiving unit 47 is supplied as a timing signal to the timing management unit 48 by synchronizing to the timing related to demodulation between the base stations. In the timing management unit 48, the timing signal supplied from the common pilot signal reception unit 47 is distributed to each processing unit in the mobile communication terminal 2, and a process of synchronizing with the base station is executed.

Next, a structure required for the uplink packet communication will be described.

First, the operation of the autonomous mode is described.

In autonomous mode operation, the transmission permission information reception unit 49 within the mobile communication terminal 2 receives the transmission permission margin from the base station in advance using a channel of DL-SACCH or the same downlink signaling. The transmission permission limit is notified from the transmission permission information receiving unit 49 to the uplink packet transmission managing unit 51. Here, the transmission timing of the autonomous mode is arbitrary.

Thereafter, if the user sets data to be transmitted from the mobile communication terminal 2 to the base station, the data is stored in the transmission data buffer 58 of the uplink packet communication.

In the autonomous mode, in order to restart transmission, the uplink packet transmission managing section (communication managing section) 51 specifies a TFRI that balances the amount of transmission data in consideration of the transmission permission boundary, and notifies the TFRI to the TFRI transmission processing section 53.

The TFRI transmission processing unit 53 sets a TFRI in the UL-TFRI-CCH, and transmits the TFRI to the base station according to the above-described transmission operation. Thus, the transmission operation can be controlled with the noise increase factor suppressed within the above transmission permission limit specified by the base station.

The EUDTCH transmission processing unit 52 converts the data stored in the transmission data buffer 58 for uplink packet communication into a transmission format specified by the TFRI, and sets the data itself in the EUDTCH, thereby transmitting the data to the base station in accordance with the above-described transmission operation.

In the base station, if the packet data is received from the mobile communication terminal 2, a response signal corresponding to the packet data is set in the DL-ACK/NACK-CCH, and the packet data is transmitted. The response signal receiving section 57 in the mobile communication terminal 2 determines ACK/NACK from the received DL-ACK/NACK-CCH in accordance with the above-described reception operation.

If the response signal receiving unit 57 determines ACK, the determination result is notified to the upstream transmission packet management unit 51. Thereafter, the uplink transmission packet management unit 51 shifts to a process of transmitting the following packet data to the base station.

On the other hand, when it is determined to be NACK, the uplink transmission packet management unit 51 shifts to a process of retransmitting the packet data determined to be NACK. Here, the EUDTCH transmission processing unit 52 retransmits the data having redundancy such as incremental redundancy in accordance with the retransmission need.

Next, the operation of the scheduling mode is described.

In the scheduling mode operation, if data transmitted from the mobile communication terminal 2 to the base station by the user is set, the transmission data is accumulated in the transmission data buffer 58 of the uplink packet communication.

After that, the buffer status transmitter 55, which has received the instruction from the uplink packet transmission manager 51, sets the limits such as the data amount of data to be transmitted to the base station and the transmission power of the terminal 2 in the UL-SICCH, and transmits the data to the base station according to the aforementioned transmission operation.

The base station, if receiving the UL-SICCH signal, determines an appropriate timing with which interference to the signal from each terminal 2 is minimum by considering the state of the transmission data buffer 58 of each terminal 2 accommodated in the own cell. In this way, the base station can perform transmission in accordance with the transmission operation by setting a transmission permission instruction to each terminal 2 in the DL-SACCH at the timing.

The transmission permission information receiving unit 49 in the mobile communication terminal 2 receives signals such as the transmission rate and the subframe timing permitted by the base station set in the DL-SACCH. This information is transferred from the transmission permission information receiving unit 49 to the timing management unit 48 and the above-described packet transmission management unit 51.

In the uplink packet transmission managing section 51, a TFRI balanced in the amount of transmission data is specified, and notified to the TFRI transmission processing section 53. The TFRI transmission processing unit 53 sets a TFRI in the UL-TFRI-CCH, and transmits the TFRI to the base station according to the aforementioned transmission operation.

The EUDTCH transmission processing section 52 reads out the data accumulated in the uplink packet communication transmission data buffer 58, converts the TFRI transmitted by the TFRI transmission processing section 53 into a specific transmission format, sets the data itself in the EUDTCH, and transmits the data to the base station in accordance with the transmission operation.

At the base station, if the above-mentioned packet data is received from the mobile communication terminal 2, it is transmitted by setting a response signal corresponding thereto in the DL-ACK/NACK-CCH. The response signal receiving section 57 in the mobile communication terminal 2 determines ACK/NACK from the received DL-ACK/NACK-CCH in accordance with the above-described reception operation.

If the response signal receiving unit 57 determines ACK, the determination result is notified to the upstream transmission packet management unit 51. Thereafter, the uplink transmission packet management unit 51 shifts to a process of transmitting next packet data to the base station.

On the other hand, when it is determined to be NACK, the uplink transmission packet management unit 51 proceeds to a process of retransmitting the packet data determined to be NACK.

Here, the EUDTCH transmission processing unit 52 retransmits data having redundancy such as incremental redundancy in accordance with the retransmission need.

Next, a description will be given of a necessary structure for changing the transmission mode.

First, the uplink packet transmission managing unit 51 compares the threshold value supplied from the threshold value changing unit 50 with the amount of data staying in the uplink packet communication transmission data buffer 58.

At this time, if the hold up amount is larger than the threshold, the uplink packet transmission management unit 51 notifies the transmission mode switching unit 54 that the transmission mode switching is completed.

When the transmission mode switching by the transmission mode switching unit 54 is completed, the buffer status transmitting unit 55 sets information indicating the completion of the transmission mode switching in the UL-SICCH, and transmits the information to the base station according to the aforementioned transmission operation.

In addition, the TFRI transmission processing unit 53 may set information representing the end of transmission mode switching in UL-TFRU-CCH and transmit to the base station. Further, the protocol processing unit 56, which has received the information indicating the transmission mode switching from the transmission mode switching unit 54, notifies the respective channel transmitting units 60 of the information.

In this way, the uplink channel transmission units 60 can set information indicating the transmission mode switching in the DPCH as a message and transmit the message to the base station. In this way, the mobile communication terminal 2 notifies the base station of the switching of the transmission mode using any one of the channels.

Next, a description will be given of a configuration necessary for changing the threshold value relating to transmission mode switching.

First, when the base station notifies that the threshold value of the terminal 2 is changed together, information on the threshold value is inserted into the report information (BCH) from the base station to the mobile communication terminal 2.

The report information unit 61 in the mobile communication terminal 2 receives a whole set of report information from the base station side according to the aforementioned receiving operation and notifies it to the protocol processing unit 56. In the protocol processing unit 56, the contents of the report information are interpreted.

In this case, if the protocol processing unit 56 interprets the report information as an instruction to change the threshold value of the uplink packet communication transmission data buffer 58, the threshold value to be changed is set in the threshold value changing unit 50 by the instruction.

Thereafter, the threshold changing unit 50 notifies the uplink packet transmission managing unit 51 of the changed threshold. In this way, the mobile communication terminal 2 can switch the transmission mode with the changed threshold as a reference.

Next, a case of switching the above threshold in the layer 3 message will be described.

In this case, as the channels to be used, both individual channels and common channels can be considered.

First, a case where the threshold value is changed using an individual channel will be described.

The individual channel is a channel used in the case where a threshold value is specified for each terminal.

Each channel (downlink DPCH) set by the message relating to the threshold value transmitted by the downlink individual channel transmitting section 29 in the base station is received by each downlink channel receiving section 63 in the terminal 2, and is notified to the protocol processing section 56. The protocol processing unit 56 interprets the contents of the individual channel.

In this case, if the protocol processing unit 56 interprets the message set in the individual channel as an instruction to change the threshold value, the threshold value changing unit 50 sets the threshold value to be changed based on the message. Thereafter, the threshold changing unit 50 notifies the uplink packet transmission managing unit 51 of the changed threshold.

Further, the uplink individual channel transmitting section 60 sets information indicating switching of the transmission mode in the uplink DPCH as a message, and transmits the message to the base station.

The case of switching the above threshold value is described by using a common channel.

The common channel is a channel used when the individual channel is released in advance and the threshold value is specified for each terminal 2. In particular, in the case where individual channels are temporarily released in order to reduce power consumption, common channels may be used in this case.

A message set in a common channel (FACH) from a base station can be received by the downlink common channel receiving unit 62 according to the aforementioned receiving operation. Thereafter, the message is sent from the downlink common channel receiving unit 62 to the protocol processing unit 56. In the protocol processing unit 56, the contents of the above-described message are explained.

In this case, if the message for setting the common channel is interpreted as an instruction to change the threshold, the protocol processing unit 56 sets the threshold to be changed in the threshold changing unit 50 by using the message. Thereafter, the threshold changing unit 50 notifies the uplink packet transmission managing unit 51 of the changed threshold.

Further, uplink common channel transmitter section 59 sets information indicating a change in transmission mode as a message in the RACH.

Next, a case of switching the above threshold value using physical layer signaling will be described. The physical layer signaling is to allocate information related to the threshold value to a certain bit related to physical layer information for setting a physical layer communication condition between the mobile communication terminal 2 and the base station. The physical layer information may be set in DL-SACCH, for example.

The physical layer signaling can be used in the case of specifying the above threshold value for each terminal 2, and can be specified at high speed according to the above case.

The transmission permission information reception unit 49 obtains an information indication relating to the physical layer inserted in the DL-SACCH from the base station, and notifies it to the protocol processing unit 56. The protocol processing unit 56 interprets the information content received by the sending license information receiving unit 49.

When the information is interpreted as an instruction to change the threshold value, the protocol processing unit 56 sets the threshold value to be changed in the threshold value changing unit 50 using the information. Then, the threshold changing unit 50 notifies the uplink packet transmission managing unit 51 of the threshold changed by the information.

Fig. 12 is a block diagram showing an internal configuration of the base station control apparatus in fig. 1, and the basic operation of the base station control apparatus 3 will be described using this figure. In fig. 12, in order to prevent the description from being complicated, the names of the constituent elements to be described later are described by simplified names, and the same reference numerals denote the same constituent elements.

The QoS parameter mapping unit 64 selects a radio resource and a parameter associated therewith that satisfy QoS (quality of service) (for example, an allowable delay or the like) specified for communication between the mobile communication terminal 2 and the base stations 4a and 4 b. The parameters related to the communication include, for example, a mode related to an RLC (radio link control) layer, a transport block size number related to a physical layer, a CRC (cyclic redundancy check) bit number, and the like.

The congestion control unit 65 is for preventing congestion from being generated in communication between the mobile communication terminal 2 and the base station, and performing call restriction and the like. The radio resource management unit 66 manages information on radio resources (for example, channels, power, codes, and the like) and measurement data, and notifies each base station of the management information according to the need at the time of communication between the mobile communication terminal 2 and the base station. The congestion limit may be calculated by the radio resource managing unit 66.

The radio resource managing section (communication resource managing section) 66 sets a margin with respect to the congestion limit in the base station by considering a QoS parameter such as delay. In the base station, if the noise increase factor is within the allowable limit, an instruction to switch the communication mode of terminal 2 in the own cell is performed.

In the conventional mobile communication system, if the noise increase factor is within the congestion limit, the communication condition between the base station and the terminal is determined in advance according to the base station control autonomy, and the communication between the base station and the terminal is controlled according to the communication condition notified by the base station control means.

However, in this configuration, since there is a communication delay between the base station control apparatus and the base station, there is an inevitable problem that the communication quality between the base station and the terminal is limited.

Therefore, in the mobile communication system of the present invention, the base station control apparatus should set a margin of tolerance for redundancy, which also has relative interference, in the base station with respect to the congestion margin, in consideration of the requirements of QoS parameters such as the operating state and delay from outside the target cell.

That is, the above-mentioned tolerance limit should be only an interference component considering the requirements of QoS parameters such as the operating state and delay other than the target cell, and be smaller than the interference amount range that the congestion limit can tolerate.

Thus, the base station performs a part of processing for determining a communication condition when the noise increase factor is within the above-described allowable limit. For example, the base station appropriately performs limit assignment for the noise increase factor of each pattern related to the allowable limit in accordance with the current communication condition or the like.

Thus, the base station can quickly determine the communication condition based on the communication QoS between the terminals without completely depending on the communication condition notified from the base station control device, and can efficiently perform data communication based on the change in the noise increase factor according to the change in the communication load.

The core network protocol processor 67 processes protocols related to communication on the network side. The wireless network protocol processing unit 68 processes protocols related to communication on the base station side.

Next, the operation of the mobile communication system of embodiment 1 is described.

As described above, if the previous transmission data is accumulated, the communication mode can be switched to the autonomous mode next time by setting the communication mode switching threshold value relating to the transmission data buffer in the mobile communication terminal 2 to the scheduling mode. Next, 3 methods of performing signaling for changing the threshold are described.

The 1 st method is a method of notifying the terminals 2 in the cell of the change together by setting the threshold change information in the report information. In addition, the 2 nd method is a method of notifying the terminal 2 of a change by setting change information of the threshold value on an individual channel or a common channel. Further, the 3 rd method is a method of notifying each terminal 2 of the change of the threshold value change information by physical layer signaling.

First, the 1 st method will be described.

The method can change the threshold value according to the number of terminals operating in a scheduling mode, the number of terminals operating in an autonomous mode, their operating states and the operating conditions of each channel in the current cell, and can properly adjust the distribution of the noise increasing factor in the cell.

Fig. 13 is a diagram showing an example of assigning a noise rise factor margin of a base station when the base station control autonomously determines a terminal transmission mode switching threshold value according to embodiment 1 of the method 1. Fig. 14 is a diagram for describing a change of the transmission mode switching threshold value according to the noise rise factor limit assignment shown in fig. 13. The basic idea of the 1 st method is described using these figures.

First, it is assumed that a plurality of mobile communication terminals 2 are accommodated in a cell as a state before changing the transmission mode switching threshold. In addition, of the noise increase factor limits of the base station, the allowable limit for the noise increase factor due to the autonomous mode and the scheduling mode and the allowable limit for the noise increase factor due to the transmission of the individual channel or the like (other range of the individual channel in the figure) may be allocated as shown in fig. 13 (a).

Here, the above-mentioned noise rise factor limit of the base station is an allowable limit that should be considered based on the operating state and QoS of other cells and also has a margin with respect to interference.

In this case, the threshold of the transmission data buffer of the mobile terminal 2 has a relationship shown in fig. 14(a) with respect to the transmission data in the buffer.

The data transmission within an individual channel may be assumed to be a certain amount of data transmission. At this time, the base station control entity 3 manages the noise increase factor due to the transmission of the individual channel by securing a required tolerance.

Thus, if the frequency of data transmission through an individual channel between terminal 2 and the base station increases, the base station control entity 3 instructs the base station to increase the allowable margin required for data transmission by the individual channel.

Data transmission through the individual channel is performed by each terminal 2. Therefore, if the data transmission frequency of the individual channel increases, the allowable limit of the individual channel can be secured in accordance with the allowable limit assigned to each terminal 2 within the noise increase factor limit of the base station.

Thus, as shown in fig. 13(b), the allowable limit assigned to the noise increase factor due to the autonomous mode in the noise increase factor limit of the base station can be reduced by only the component of the increase in the allowable limit of the individual channel. In this case, the noise increase factor limit for each terminal can be reduced when the number of terminals is the same.

In this case, if the transmission mode switching threshold value is set to a relatively small value as shown in fig. 14(a) for the transmission data buffer, data transmission exceeding the autonomous mode allowable limit can be performed.

That is, if the threshold value is still as shown in fig. 14(a), the terminal 2 that performs data transmission with a large amount of data in the base station cannot tolerate the noise increase factor in the data transmission.

Therefore, in the case of the allocation structure of the noise increase factor limit shown in fig. 13(b), as shown in fig. 14(b), the threshold of the transmission data buffer of the terminal 2 accommodated in the cell can be lowered together with the report information according to the method 1, and the terminal 2 that performs data transmission with a large amount of data can be changed from the autonomous mode to the scheduling mode.

At this time, in the terminal 2 that performs data transmission with a small amount of data, if the amount of transmission data does not exceed the threshold after the change, the autonomous mode is still maintained.

Wherein if the threshold is lowered too much each time, the balance of the number of terminals of the autonomous mode and the scheduling mode is broken, and therefore it is desirable to slowly lower the threshold.

Fig. 15 is a diagram showing a change procedure in a case where transmission data threshold change is performed by the method 1 in the mobile communication system according to embodiment 1. The base station measures the noise rise factor of the current base station side (step ST 1). Specifically, as shown in fig. 10, the noise increase factor (interference amount) at the current base station side is measured by the desired radio wave measuring unit 16 and the interference radio wave power measuring unit 17 in the base station.

Thereafter, the base station notifies the base station control apparatus 3 of the noise rise factor measured in step ST1 (step ST 2). Further, the base station notifies the base station control apparatus 3 of the number of terminals operating in the autonomous mode and the scheduling mode in the own cell (step ST 3).

Next, the radio resource management unit 66 in the base station control apparatus 3 obtains the operation status (for example, the number of accommodated terminals in the cell of the peripheral base station is also included) of the base station around the target base station (hereinafter, referred to as the peripheral base station) (step ST 4).

In a case where a plurality of terminals 2 of surrounding base stations are in an operating state, the terminals 2 may move to an area where handover is performed. At this time, the radio resource managing unit 66 in the base station control apparatus 3 may have a congestion limit in which a noise increase factor due to handover is considered as an allowable limit to be notified to the base station.

Next, the radio resource managing unit 66 obtains the operating conditions of the individual channels of the base station (step ST 5). In general, since an individual channel can be used for data transmission from the base station to the terminal 2 at the time of soft handover, the base station control apparatus 3 needs to know its operation status.

The radio resource managing section 66 judges whether or not the base station noise rise factor limit is excessive and conversely whether or not the limit is insufficient for the current noise rise factor obtained from step ST1 to step ST5 (step ST6), and the radio resource managing section 66 shifts to a process of changing the noise rise factor of the autonomous mode and the scheduling mode in accordance with the judgment result.

Here, the noise rise factor limit is assigned as the above-mentioned allowable limit specified to the base station by the base station control device 3, and the assigned amount of the noise rise factor limit assigned in each mode is specified. In fig. 13, for example, the noise increase factor limit for the scheduling pattern is indicated by a portion with a hatched limit as the scheduling pattern.

If the radio resource managing unit 66 previously generates a base station noise rise factor limit that is too small for the current noise rise factor and determines that a change in the base station assigned noise limit is necessary, the base station is instructed to change the noise rise factor limit of the autonomous mode and/or the scheduling mode (step ST 7).

On the other hand, if the radio resource managing unit 66 does not previously generate the noise increase factor limit of the too small base station with respect to the current noise increase factor and determines that the change of the noise increase factor limit is not necessary, it does not instruct the change of the noise increase factor limit.

When the base station receives the instruction to change the noise increase factor limit from the base station control device 3, the base station changes the noise increase factor limit in accordance with the instruction (step ST 18). For example, as described with reference to fig. 13, when the frequency of data transmission using the individual channel increases, the base station control device 3 may increase the noise increase factor limit of the individual channel to the noise increase factor limit of the base station, and instruct to reduce the noise increase factor limit used in the autonomous mode only for the increased amount.

Next, if there is a notification from the base station indicating that the transmission mode switching threshold of terminal 2 should be changed, radio resource managing section 66 determines whether or not the threshold should be changed by a certain value due to an appropriate amount of interference in communication between the base station and terminal 2, taking into account the current traffic volume, the noise rise factor of the base station, and the allowable limit thereof (step ST 9).

Thereafter, the radio resource managing section 66 reports information on the change of the threshold value including the determination result threshold value to the base station (step ST 10).

The base station that has received the information on the threshold change from the base station control device 3 sets the information including the threshold in the report information (BCH) and transmits the information to the terminals 2 all at once (step ST 11).

The terminal 2 that has received the report information performs the same operation as described in fig. 11, and reads out the transmission mode switching threshold from the report information to change the threshold (step ST 12).

The operation of step ST9 in fig. 15 of the mobile communication system of embodiment 1 will be described in detail using the flowchart shown in fig. 16.

First, the uplink packet transmission management unit 24 in the base station compares the data amount of the transmission data buffer reported from the terminal 2 in the own cell with the threshold set in the terminal 2, and determines whether or not the threshold should be changed. In this way, if it is determined that the threshold should be changed, the base station can notify the base station control apparatus 3 of the instruction according to the aforementioned transmission operation.

In step ST1a, the radio resource managing unit 66 in the base station control apparatus 3, which has received an instruction from the base station that the threshold should be changed, estimates a noise increase factor due to data transmission of the individual channel based on the operating condition of the individual channel of the base station.

Next, the radio resource managing unit 66 estimates an allowable limit of the relative noise increase factor based on the current operating state of the base station other than the base station (step ST2 a). For example, when the number of terminals of the surrounding base station is large, the terminal 2 may move within the area where handover is performed. In this case, the radio resource managing unit 66 estimates a limit in consideration of the noise increase factor caused by the handover.

In this way, if a limit in consideration of the operating state of the surrounding base station is determined (for example, a limit in consideration of the number of terminals of the surrounding base station, or the like), the radio resource managing unit 66 sets the limit further to the allowable limit for the noise increase factor set in the base station.

That is, a limit obtained by subtracting a limit in consideration of the operation state of the surrounding base station from the allowable limit is set as a new allowable limit to be set in the base station.

Next, the radio resource managing unit 66 obtains the noise increase factor of the scheduling pattern in the base station cell and the number of terminals thereof (step ST3 a). Thereafter, the radio resource managing unit 66 estimates the allowable limit for each of the noise increase factor due to the data transmission of the individual channel determined in step ST1a and the noise increase factor of the scheduling pattern in the base station cell determined in step ST3 a.

In step ST4a, the radio resource managing unit 66 subtracts the limit for the individual channel and the limit for the scheduling pattern from the total allowable threshold values of the base stations estimated from the operating states of the surrounding base stations in step ST2a, thereby obtaining an allowable limit for the noise increase factor (noise increase factor limit) with respect to the autonomous pattern of the base stations.

Next, the radio resource managing unit 66 determines whether or not the number of terminals operating in the autonomous mode in the base station cell is appropriate with respect to the noise increase factor limit of the base station autonomous mode determined in step ST4a (step ST5 a).

The base station is notified of the amount of transmission data from the transmission data buffer of each terminal 2 in the own cell. Further, the base station control device 3 receives the transmission data amount notification from the base station. The radio resource management unit 66 in the base station control apparatus 3 calculates an average value in a predetermined period in advance for the transmission data amount of the terminal 2 notified by the base station.

In addition, if there is a small base station autonomous mode noise increase factor limit with respect to the average value of the amount of data transmitted by the terminal 2, the radio resource managing unit 66 statistically obtains the percentage of the number of terminals that perform data transmission that cannot be demodulated because the noise increase factor limit with respect to the base station is exceeded with respect to the number of all terminals, and the like in advance.

Here, for example, a state in which the number of autonomous mode terminals is too large is defined as a case in which the number of terminals that cannot demodulate data transmission due to exceeding the autonomous mode noise rise factor limit exceeds a predetermined ratio with respect to all the terminals, whereas a state in which the number of autonomous mode terminals is too small is defined as a case in which the number is less than the predetermined ratio, and a state in which the number of autonomous mode terminals is appropriate is defined as the other cases.

In step ST5a, the radio resource managing unit 66 checks how many noise increase factor limits the current base station autonomous mode with respect to the above average value is, and determines whether the number of autonomous mode terminals is appropriate based on the result.

In step ST5a, if it is judged that the number of autonomous mode terminals is too large, the radio resource managing unit 66 down-regulates the switching threshold set by the current terminal 2 (step ST6 a). The noise rise factor limit assigned to the autonomous mode terminal 2 may be assigned according to the number of terminals within the base station autonomous mode noise rise factor limit.

Therefore, if the number of autonomous mode terminals is large, the noise increase factor limit assigned to each terminal 2 in the autonomous mode is reduced because the noise increase factor limit of the base station autonomous mode is constant.

Therefore, if the noise increase factor limit assigned to each terminal 2 is reduced, the noise increase factor exceeding the demodulatable range occurs in the terminal 2 if transmission is performed at a data rate that balances the amount of transmission data. The state of the number of terminals assigned exceeding the allowable limit of the demodulation range is defined as a state in which the number of autonomous mode terminals in the cell is large.

If the threshold is lowered in step ST6a, the radio resource managing unit 66 moves to the processing of step ST10 in fig. 15 and instructs the base station of the changed threshold as an information report on the change of the threshold.

In addition, if it is determined in step ST5a that the number of terminals of the autonomous mode is appropriate, the radio resource managing unit 66 maintains the current handover threshold (step ST7 a). This threshold value is indicated as a base station as an information report concerning a change in the threshold value in step ST10 in fig. 15.

If it is determined in step ST5a that the number of autonomous mode terminals is too small, the radio resource managing unit 66 up-regulates the switching threshold set in the current terminal 2 (step ST8 a). Here, the state in which the number of autonomous mode terminals is too small is a state in which a margin more than necessary is generated with respect to the noise increase factor limit assigned to each terminal 2 even if transmission is performed at a data rate that balances the amount of transmission data.

In this case, if the number of autonomous mode terminals within the cell increases due to the up-regulation threshold, the noise increase factor limit assigned to each terminal 2 can be effectively used.

In this manner, if the threshold is increased in step ST8a, the radio resource managing unit 66 moves to the process of step ST10 in fig. 15 and instructs the base station of the changed threshold as an information report relating to the change of the threshold.

However, in step ST6a and step ST8a, if the threshold adjustment is performed too much each time, there is a possibility that too many terminals 2 will switch to the transmission mode.

Therefore, considering the number of terminals in the autonomous mode in a cell, it is necessary to keep the threshold value to be adjusted up and down to a certain value every time the threshold value is adjusted, and it is desirable that the threshold value be changed slowly.

As described above, in the method 1, the change of the transmission mode switching threshold value can be notified together in the cell. Therefore, the number of times of occurrence of signaling for notifying the threshold change can be reduced.

The signaling using the above-described report information has a disadvantage that the setting cannot be performed for each terminal 2. Therefore, for example, by grouping terminals 2 in a cell based on QoS levels, the threshold value can be set for each group.

A specific grouping method is described.

In the W-CDMA scheme, 4 QoS levels (session level, stream level, interrupt level, background level) are defined. For example, terminals 2 within the cell are divided into 3 groups shown below based on the allowable amount of communication delay for such QoS levels.

Group 1 belongs to a session level and a stream level, and is a group using a communication service that handles data such as voice and video that is least tolerant of delay.

Group 2 belongs to the class of interruptions and is a group that uses communication traffic that tolerates a certain degree of delay. For example, it can be used for processing still images and text files provided through the WWW (world wide web) or the like. In the case of transmitting such data, although a certain degree of communication delay is allowed, it is uncomfortable to the user if delay is caused simply because it is not completely allowable.

Group 3 belongs to the background level and is a group using delay tolerant traffic. For example, data transfer using FTP (file transfer protocol) which allows delay required in scheduling related to communication, or the like.

The grouping of each terminal 2 in the cell can be performed by the QoS parameter mapping section 64 in the base station control apparatus 3 which grasps the QoS level of communication with the base station. In addition, the grouping result may also be stored in the QoS parameter mapping unit 64.

Next, a threshold changing process of the terminal 2 which performs grouping as described above will be described.

The radio resource managing section 66 in the base station control apparatus 3 which has received the notification indicating that the threshold should be changed from the base station determines to which group the terminal 2 whose threshold should be changed belongs based on the grouping result stored in the QoS parameter mapping section 64.

The radio resource managing unit 66 determines the magnitude of adjusting the threshold value of each group up and down based on the judgment result of the grouping. For example, the maximum threshold value may be set for the terminal 2 of the group 1 that is the least delay tolerant. In addition, the terminal 2 of the 3 rd group that allows delay can be controlled by setting a minimum threshold value.

Thus, for example, in group 1 where delay is least tolerable, mode switching can be performed as in the autonomous mode where delay is least generated.

In group 1, when the noise increase factor limit of the scheduling mode is insufficient due to an increase in the number of autonomous mode terminals, the terminal 2 having a large transmission data amount can be controlled by gradually lowering the threshold to switch to the scheduling mode.

In addition, for the delay tolerant group 2 and group 3, since switching to the scheduling mode is possible, a lower threshold value can be set than in the group 1.

However, since the number of terminals belonging to the 1 st group in the cell is small, when the base station tolerance has a margin, control can be performed by adjusting the threshold values set in the 2 nd group and the 3 rd group up in order to effectively use the tolerance.

Further, in the case where the terminals 2 belong almost to the group 1 in the cell, the fine grouping may be further performed based on the delay tolerance indicating the processing data of the terminals 2.

Next, a second method is described.

In this method, the transmission data switching threshold changing information can be set in the layer 3 message of the individual channel, the common channel, or the like, and the transmission mode can be switched to the transmission mode most suitable for each terminal.

Fig. 17 is a diagram showing an example in which the base station control device of embodiment 1 assigns the base station noise rise factor limit by the method 2 when determining the terminal transmission mode switching threshold. Fig. 18 is a diagram for describing a change of the transmission mode switching threshold value according to the allocation of the noise increase factor limit shown in fig. 17. The basic aspects of the method of fig. 2 are described using these figures.

First, the transmission mode switching threshold is set to a state before the change, and it is assumed that a plurality of mobile communication terminals 2 are accommodated in the cell. In addition, it is assumed that, among the base station noise rise factor limits, the allowable limit of the noise rise factor due to the autonomous mode and the scheduling mode and the allowable limit of the noise rise factor due to the transmission of the individual channel (other region of the individual channel in the figure) can be allocated as shown in fig. 17 (a).

Here, the noise increase factor limit of the base station is an allowable threshold value having a margin in the congestion threshold value, which is considered depending on the operating state and QoS of other cells.

At this time, the threshold of the transmission data buffer of the mobile communication terminal 2 has a relationship shown in fig. 18(a) with respect to the transmission data in the buffer.

Data transmission of an individual channel is assumed to be transmission of a certain amount of data. In this case, the base station controller 3 may perform management to ensure an allowable limit necessary for a noise increase factor due to transmission of an individual channel.

Therefore, if the data transmission frequency of the individual channel between the terminal 2 and the base station increases, the base station control device 3 instructs the base station to increase the allowable limit necessary for data transmission through the individual channel.

Data transmission of the individual channel is performed for each terminal 2. Therefore, if the data transmission frequency of the individual channel increases, it is necessary to secure a margin allowed for each channel in accordance with the margin allowed to be allocated to each terminal 2 within the margin of the noise increase factor of the base station.

As described above, as shown in fig. 17(b), the allowable limit of the noise increase factor due to the autonomous mode can be reduced by increasing the allowable limit of each individual channel within the noise increase factor limit of the base station.

In this case, the transmission mode switching threshold shown in fig. 18(a) can be set for the transmission data buffer, and data transmission exceeding the allowable limit of the autonomous mode can be performed.

That is, the threshold as shown in fig. 18(a) is still set, and the noise increase factor in data transmission is not allowed for the terminal 2 that performs data transmission with a large amount of data to the base station.

Therefore, as shown in fig. 18(b) and 18(c), the switching threshold needs to be adjusted downward. However, when adjusting the handover threshold, the requirements of the communication quality for each terminal 2 should be taken into account. For example, depending on the nature of the data processed by the respective terminals 2, the allowable delay may be different.

In the QoS class classification of the communication service of the W-CDMA system, a session type class for processing data such as audio and a stream class for processing data such as moving pictures are required to have real-time performance in order to prevent delay from giving unnatural feeling to a user. Therefore, there is a need to reduce the delay in these QoS levels as much as possible.

On the other hand, in the interactive level of processing Web data or the like and the background level of data transmission in FTP or the like, although the accuracy of transmitting data is required, the delay is not felt by the user. Therefore, these data transmissions are handled with the maximum capacity, and the problem of delay is small.

Therefore, by changing the threshold value for each terminal 2 using the method 2, the terminal 2 that processes data that does not allow delay is not only reduced in the downward transmission data buffer threshold value, but also reduced in the upward transmission data buffer threshold value as shown in fig. 18 (b).

In contrast, for the terminal 2 that processes the delay-allowable data, as shown in fig. 18(c), by increasing the magnitude of the threshold value for down-regulating the transmission data buffer, the threshold value can be made lower than in the case of fig. 18 (b).

In this manner, the terminal 2 which processes the delay intolerant data is maintained in the autonomous mode having the characteristic of hardly generating the delay communication, and only the terminal 2 which processes the delay tolerant data is guided from the autonomous mode to the scheduling mode.

At this time, as shown in fig. 17(b), the margin of the allowable limit of the terminal 2 that processes the delay-ineligible data (the noise limit assigned to the delay-ineligible terminal 1) is reduced and the margin of the allowable limit of the terminal 2 that processes the delay-allowable data (the noise limit assigned to the delay-allowable terminal 1) is increased among the allowable limits of the base station autonomous mode.

In addition, it is desirable to slowly lower the threshold value because if the threshold value is lowered too much at one time, the total number of terminals in the autonomous mode and the dispatch mode will increase dramatically.

Fig. 19 is a diagram showing a change procedure in the case where the mobile communication system of embodiment 1 performs the transmission data buffer threshold change by the method 2. The base station measures the noise increase factor of the current base station (step ST1 b). Specifically, as shown in fig. 10, the noise increase factor (interference amount) of the current base station can be measured by the required radio wave power measuring unit 16 and the interference radio wave power measuring unit 17 in the base station.

Thereafter, the base station notifies the base station control apparatus 3 of the noise rise factor measured in step ST1b (step ST2 b). Further, the base station notifies the base station control apparatus 3 of the number of terminals operating in the autonomous mode and the scheduling mode in the own cell (step ST3 b).

Next, the radio resource management unit 66 in the base station control apparatus 3 obtains the operation status of the surrounding base stations (for example, the number of terminals accommodated in the cells of the surrounding base stations is also included) (step ST4 b).

In a case where a plurality of terminals 2 of surrounding base stations are in operation, there is a possibility that the terminals 2 move within an area where handover is performed. In this case, the radio resource managing unit 66 in the base station control apparatus 3 further has a noise increase factor in consideration of the switching, in the congestion limit which is the allowable limit notified by the base station.

Next, the radio resource managing unit 66 obtains the operating conditions of the individual channels of the base station (step ST5 b). In general, since an individual channel can be used for transmitting data from a peripheral base station to the terminal 2 in soft handover, the base station control apparatus 3 grasps the operation state thereof.

The radio resource managing unit 66 judges whether or not there is a margin in the noise increasing factor limit of the base station for the current noise increasing factor determined from step ST1b to step ST5b, and conversely, whether or not the limit is insufficient (step ST6 b). Based on the determination result, the radio resource managing section 66 shifts to a process of changing the noise increase factor limit of the autonomous mode and the scheduling mode.

If the radio resource managing unit 66 has generated too little in advance in the base station noise rise factor limit with respect to the current noise rise factor and has determined that the noise rise factor limit assigned in the base station needs to be changed, it instructs the base station to change the noise rise factor limit of the autonomous mode and/or the scheduling mode (step ST7 b).

On the other hand, if the radio resource managing section 66 does not previously make the noise rise factor limit of the base station too small with respect to the current noise rise factor and determines that it is not necessary to change the noise rise factor limit, it does not instruct to change the noise rise factor limit.

When the base station receives the noise increase factor limit change instruction from the base station control device 3, the base station changes the noise increase factor limit according to the current instruction (step ST8 b). For example, when the frequency of data transmission through the individual channel increases as described with reference to fig. 17, the base station control device 3 may increase the noise increase factor limit of the individual channel within the base station noise increase factor limit, and instruct to reduce the noise increase factor limit used by the autonomous mode in the increase component.

Next, if there is a notification from the base station indicating that the transmission mode switching threshold of the terminal 2 should be changed, the radio resource managing unit 66 judges whether or not the switching threshold of each terminal 2 should be changed to a certain value by taking into account the current traffic situation and the base station noise rise factor and its allowable limit (step ST9 b).

Thereafter, the radio resource managing section 66 transmits information on the threshold change including the determination result threshold to the base station as a layer 3 message (step ST10 b).

The base station that has received the information on the threshold change from the base station control apparatus 3 uses the individual channel (DPCH) when establishing communication between the terminal 2 to which the threshold is set and the individual channel (DPCH), and transmits the information to the terminal 2 to which the information is to be transmitted using the common channel (FACH) if it is determined that communication is not to be performed on the individual channel (step ST11 b).

The terminal 2 that has received this information reads out the transmission mode switching threshold from the information set in the individual channel or the common channel by using the same operation as described with reference to fig. 11, thereby changing the threshold (step ST12 b).

Thereafter, the uplink individual channel transmitter unit 60 in the terminal 2 sets information for instructing to change the handover threshold value as a message in the uplink DPCH or RACH, and transmits the message to the base station (step ST13 b). The base station having received this message notifies the base station control apparatus 3 of the instruction to end the change (step ST14 b).

The operation of step ST9b in fig. 19 of the mobile communication system according to embodiment 1 is described in detail using a flowchart shown in fig. 20.

First, the uplink packet transmission management unit 24 in the base station compares the transmission data buffer data amount reported from the terminal 2 in the own cell with the threshold set in the terminal 2, and determines whether or not the threshold should be changed. Accordingly, if it is determined that the threshold should be changed, the base station notifies the base station control apparatus 3 of the instruction according to the transmission operation.

In step ST1c, the radio resource managing unit 66 in the base station control apparatus 3, which has received the notification indicating that the threshold should be changed from the base station, estimates the noise increase factor due to data transmission in the individual channel based on the individual channel operating condition of the base station.

Next, the radio resource managing unit 66 estimates an allowable limit of the relative noise increase factor based on the current operating state of the base station other than the base station (step ST2 c). For example, when the number of terminals of the surrounding base station is large, the terminal 2 may move within the area where handover is performed. In this case, the radio resource managing unit 66 estimates a boundary that takes into account the noise increase factor caused by the handover.

Thus, if a limit is determined that takes into account the operating state of the surrounding base station (for example, a limit in the case where the number of terminals of the surrounding base station is large), the radio resource managing unit 66 further has the limit with respect to the allowable limit of the noise increase factor set in the base station.

That is, a limit obtained by subtracting a limit in consideration of the operating state of the surrounding base station or the like from the allowable limit is set as a new allowable limit to be set in the base station.

Next, the radio resource managing unit 66 obtains the scheduling pattern noise rise factor and the number of terminals in the base station cell (step ST3 c). Thereafter, the radio resource managing unit 66 sets the allowable limit of the noise increase factor due to the data transmission of the individual channel determined in step ST1c and the allowable limit of the scheduling pattern noise increase factor in the base station cell determined in step ST3 c.

In step ST4c, the radio resource manager 66 subtracts the margin for the individual channel and the margin for the scheduling pattern from the total allowable margin for the base station estimated from the operating state of the surrounding base stations in step ST2c, and obtains an allowable margin for the noise increase factor (noise increase factor margin) for the autonomous mode of the base station.

At this time, when receiving a desired transmission data rate from each terminal 2, the radio resource managing unit 66 adjusts the allowable limit (allowable limit) for the scheduling mode in consideration of the desired transmission data rate (step ST5 c).

When transmitting data in the scheduling mode with the base station, the terminal 2 notifies the base station of the transmission data rate desired by itself. The uplink packet transmission management unit 24 in the base station manages the transmission data rate desired by the terminal 2 and the scheduling of the data communication.

The uplink packet transmission management unit 24 also notifies the radio resource management unit 66 in the base station control device 3 of the transmission data rate desired by the terminal 2.

In the radio resource managing unit 66, while estimating the noise increase factor from the transmission data rate of the terminal 2 operating in the scheduling mode in the cell, the allowable limit for the scheduling mode is adjusted by finding the allowable limit corresponding to the noise increase factor.

Thereafter, the radio resource managing section 66 adjusts the allowable limit of the autonomous mode obtained in step ST4c, using the allowable limit of the scheduling mode adjusted as described above.

Next, the radio resource managing unit 66 determines whether or not the number of terminals operating in the autonomous mode in the base station cell is appropriate with respect to the noise margin of the autonomous mode of the base station obtained as described above (step ST6 c).

Each terminal 2 in the own cell reports the transmission data amount in the transmission data buffer to the base station. Further, the base station control device 3 receives the transmission data amount notification from the base station. The radio resource management unit 66 in the base station control apparatus 3 calculates an average value in a predetermined period of the transmission data amount of the terminal 2 notified by the base station in advance.

In addition, if there are some noise increase factor limits of the base station autonomous mode with respect to the above-mentioned average value of the transmission data amount of the terminal 2, the radio resource managing unit 66 statistically obtains in advance the percentage of the number of terminals that perform data transmission that cannot be demodulated because the noise increase factor limits with respect to the base station are exceeded with respect to the total number of terminals.

Here, for example, a case where the number of terminals that perform data transmission that cannot be demodulated due to exceeding the noise rise factor limit of the autonomous mode exceeds a predetermined ratio with respect to the total number of terminals is defined as a state where the number of autonomous mode terminals is excessive, whereas a case where the number of terminals is equal to or less than the predetermined ratio is defined as a state where the number of autonomous mode terminals is too small, and the other cases are defined as a state where the number of autonomous mode terminals is appropriate.

In step ST6c, the radio resource managing unit 66 checks how many noise increase factor limits the current base station autonomous mode is with respect to the average value, and determines whether or not the number of autonomous mode terminals is appropriate based on the result.

Here, if the radio resource managing unit 66 judges that the number of autonomous mode terminals is excessive, the QoS parameter mapping unit 64 in the base station control device 3 detects whether or not a delay is allowed in the autonomous mode terminal 2 (step ST7 c).

The state in which the number of autonomous mode terminals in the cell is excessive is a state in which the number of terminals that can be provided beyond the allowable limit of the demodulation range for the noise increase factor in the autonomous mode is determined to be excessive.

The QoS parameter mapping unit 64 determines whether delay tolerant data is being processed in the terminals 2 operating in the autonomous mode based on the QoS levels of the terminals 2. For example, it is determined whether delay is allowed or not allowed in the above-described level 4 of QoS. In the W-CDMA system, the delay amount (transmission delay) is defined in units of ms in the session type level and the stream level, and therefore, it is possible to determine a delay that can be tolerated in units of ms.

Next, the radio resource manager 66 sets the terminal 2, which has been determined by the QoS parameter mapping unit 64 in step ST7c as not being delay tolerant, to a threshold value that maintains the current handover threshold value or sets the current handover threshold value to a lower down width than in the case of delay tolerant (step ST10 c).

Here, the radio resource managing unit 66 increases the downward adjustment range of the handover threshold of the terminal having a large delay amount (slow delay tolerance) among the QoS parameters of the terminal 2 belonging to the QoS class not allowing delay. For example, for the magnitude of the down-regulation of the handover threshold, the degree of mixing in the cell corresponding to the autonomous mode terminal 2 may be set to a coefficient k.

In the case where there is a terminal 2 whose delay amount is set to QoS parameters of 20ms and 80ms, if it is assumed that the coefficient k is 1, the down-regulation width of the switching threshold can be expressed as follows.

The down-regulation amplitude of terminal 2 with a delay of 20ms is: k 20/(20+80) ═ 1/5 ═ 20%.

The down-regulation amplitude of terminal 2 with a delay of 80ms is: k 80/(20+80) ═ 4/5 ═ 80%.

In addition, by adjusting the switching threshold values of the plurality of autonomous mode terminals 2 downward, if the component imposed to ensure the allowable limit of the autonomous mode among the base station scheduling mode allowable limits is eliminated, the radio management unit 66 maintains the current threshold value by setting the above coefficient k to 0.

The radio resource manager 66 sets the terminal 2 determined to be delay-tolerant by the QoS parameter mapping unit 64 in step ST7c to down-shift the handover value to a larger down-shift width than in the case of step ST10c (step ST11 c). In this manner, the radio resource managing unit 66 sets the switching threshold by shifting from the redundant autonomous mode to the scheduling mode.

In addition, if it is determined in step ST6c that the number of terminals in autonomous mode is appropriate, the radio resource managing unit 66 maintains the current handover threshold (step ST8 c).

Further, if it is determined in step ST6c that the number of terminals in autonomous mode is too small, the radio resource managing unit 66 raises the switching threshold currently set in the terminal 2 (step ST9 c).

Here, the state in which the number of autonomous mode terminals is too small means a state in which, even if data transmission is performed at a data rate that balances the amount of transmission data, a margin more than necessary is required for the noise increase factor limit assigned to each terminal 2.

In this case, if terminals of the intra-cell autonomous mode increase by adjusting the threshold up, the noise increase factor limit assigned to each terminal 2 can be effectively used.

In this way, the radio resource managing unit 66 can determine the magnitude of change of the switching threshold value based on the transmission data rate, the number of autonomous mode terminals, the noise rise factor limit of the scheduling mode, and the delay amount that should be allowed.

If the handover threshold is determined in any of steps ST8c to ST11c, the radio resource managing unit 66 proceeds to the process of step ST10b of fig. 19, generates a layer 3 message containing the changed threshold, and transmits it to the base station.

The base station which has received the threshold change message from the base station control autonomous unit 3 transmits the information to the target terminal 2 by using the individual channel (DPCH) when communication between the terminal 2 to be set with the threshold and the individual channel (DPCH) is established and by using the common channel (FACH) if communication on the individual channel is not established in step ST11b of fig. 19.

Thereafter, in the processing from step ST12b to step ST14b in fig. 19, the mobile communication terminal 2 changes the switching threshold of the own transmission data buffer.

In step ST9c, the QoS parameter mapping section 64 determines whether or not delay is allowed based on the QoS parameter, and based on the determination result, the radio resource managing section 66 can be configured to set a larger value than the allowed delay for the switching threshold value up-regulation width of the terminal 2 that does not allow delay. This makes it possible to switch each terminal to the most suitable transmission mode.

In addition, in step ST9c, step ST10c, and step ST11c, if the threshold value up-down adjustment width is performed once too much, there is a possibility that the terminal 2 exceeding the necessity may be switched to the transmission mode. Therefore, considering the number of autonomous mode terminals in a cell, it is desirable to suppress the magnitude of threshold adjustment up and down each time the threshold is performed to a certain value, and it is desirable that the threshold can be changed slowly.

As described above, in the method 2, since the handover threshold is set for each terminal 2 in the cell, a communication mode corresponding to a communication condition required for each terminal 2 can be set. Specifically, by switching between the autonomous mode and the scheduling mode according to whether or not delay is allowed for data handled by each terminal 2, QoS set in data communication between the terminals 2 can be secured.

In addition, in the methods of the 1 st and 2 nd, although the radio resource management unit 66 in the base station control apparatus 3 is described as a configuration for determining the communication mode switching threshold, the present invention is not limited to this.

For example, the uplink packet communication managing unit 24 in the base station may be configured to determine the communication mode switching threshold by the base station obtaining QoS information from the base station control device 3.

The threshold value determined by the base station controller 3 may be changed in accordance with the current traffic status of the base station, and the terminal 2 may be notified of the increase. That is, the present invention also includes a configuration in which the base station and the base station control device 3 determine the threshold value in common.

In this case, the uplink packet communication management unit 24 is conceivable as a base station side configuration for changing the threshold value notified from the base station control device 3.

Next, the 3 rd method is described.

In this method, by transmitting the transmission mode switching threshold change information to each terminal using physical layer signaling (L1 signaling), each terminal can be switched to the most suitable transmission mode. In addition, in the 3 rd method, since higher physical layer signaling is used than in the 2 nd method, the handover threshold can be changed following the change in packet traffic.

The physical layer signaling (hereinafter, referred to as L1 signaling) is signaling in which information on the threshold is allocated to physical quantity layer bits for setting physical layer communication conditions between the mobile communication terminal 2 and the base station.

For example, physical layer signaling is performed by importing a new channel and its slot format. Here, the slot format is a method for specifying bit allocation in each slot in transmission packet data.

That is, in switching the threshold value change by physical layer signaling, a setting bit of switching threshold value change information in the transmission packet data is defined in the slot format.

As a specific example, UL-SICCH or the like is defined as a new channel for physical layer signaling, and 2 bits for setting a command for instructing up and down adjustment of the handover threshold finger are defined in the slot format.

In other cases, a method using punching is used. This method is to eliminate a certain part of data set in the currently used individual channel (DPCH) and insert a value for specifying a handover threshold in the part. Each data unit has strong error code correcting function in advance, so that the error code of the data unit can be corrected to a certain degree.

However, in this method, since the bit error rate increases for each data, the number of bits for setting the switching threshold cannot be too large.

Fig. 21 is a diagram showing an example of assigning a noise rise factor limit of a base station according to the 3 rd method when the base station of embodiment 1 determines a terminal transmission mode switching threshold. The basic idea of the 3 rd aspect is described using this figure.

As a state before changing the transmission mode switching threshold, it is assumed that a plurality of mobile communication terminals 2 are accommodated in the cell. As shown in fig. 21 a, it is assumed that a tolerance limit for a noise rise factor due to the autonomous mode and the scheduling mode and a tolerance limit for a noise rise factor due to transmission of an individual channel or the like (other region of the individual channel in the figure) are allocated to the noise rise factor limit of the base station.

Here, the noise increase factor limit of the base station is an allowable limit having a margin corresponding to the interference considered in accordance with the operating state and QoS of the other cell with respect to the congestion limit.

Generally, intermittent transmission is easy in packet communication. That is, when data of any size is uploaded, although the communication load increases, if the transmission is stopped, the load is reduced much.

In the case where the number of terminals in a cell is large and each terminal 2 handles completely different communication services, the temporal change in traffic is absorbed to the extent that it is statistically visible. However, when many terminals 2 in a cell process the same communication service, the traffic volume may vary over time, become overloaded, or become idle.

For example, if the packet communication frequency of the scheduling mode terminal 2 increases (becomes active), as shown in fig. 21(b), more of the limits used by the scheduling mode must be allocated within the allowable limits of the base station, and the limits used by other partially autonomous modes can be cut.

In contrast, if the packet communication frequency of the terminal in the scheduling mode decreases (becomes inactive), it is desirable to perform control by decreasing the limit used by the scheduling mode among the base station tolerance limits and increasing the limit used by the other partially autonomous mode as shown in fig. 21 (c).

As described above, when the autonomous mode limit is decreased, some terminals 2 are preferably switched from the autonomous mode to the scheduling mode, whereas when the autonomous mode limit is increased, some terminals may be switched from the scheduling mode to the autonomous mode.

Here, in order to track the traffic volume of each transmission mode that changes at a high speed, it is necessary to change the switching threshold as quickly as possible when switching the transmission mode. Thus, in method 3, higher physical layer signaling is used than for layer 3 messages.

Fig. 22 is a diagram showing a change procedure in a case where the threshold of the transmission data buffer is changed by the method 3 in the mobile communication system according to the embodiment 1. The uplink packet transmission management unit 24 in the base station is specified in advance by the base station control device 3 for the noise increase factor limit for uplink enhancement (step ST1 d).

Specifically, the radio resource managing unit 66 in the base station control device 3 determines an allowable limit of a certain range with respect to the target base station by considering the QoS parameter managed by the QoS parameter mapping unit 64, the operation state of the cell other than the target base station, and the traffic state in the cell of the target base station, and notifies the target base station of the allowable limit.

The allowable limit to be notified to the base station is a limit that can be allocated as a limit for the scheduling mode and a limit for the autonomous mode which are controllable limits in fig. 5, and a non-control limit in fig. 5 due to own-cell interference, other-cell interference, and the like.

Here, the base station control device 3 sets the base station by setting the entire allowable limit within a fixed range. On the other hand, the allocation ratio of the allowable limit to each transmission mode of the allowable limit can be determined by the uplink packet transmission management unit 24 in the base station.

Next, the uplink packet transmission management unit 24 in the base station receives a request for a transmission data rate for data transmission in the scheduling mode from the terminal 2 in the own cell (step ST2 d).

The uplink packet transmission management unit 24 has a function as a scheduler for managing data transmission in the scheduling mode, in addition to determining an allowable data rate in the autonomous mode. The transmission data rate from the terminal 2 may be recorded in the uplink packet transmission management unit 24 as a content of data transmission scheduling in the scheduling mode.

Thereafter, the uplink packet transmission management unit 24 determines whether or not the traffic load situation of the scheduling mode with respect to the allowable threshold value allocated to the base station control device 3 is appropriate, and determines whether or not the threshold value can be switched as in switching of each transmission mode, based on the determination result (step ST3 d). This process will be described in detail later using fig. 23.

If the threshold for switching is determined in step ST3d, the upstream packet transmission managing unit 24 instructs the threshold change target terminal 2 of the threshold changed by the L1 signaling according to the transmission operation described above using fig. 10 (step ST4 d).

Further, as described above, when the switching threshold value change instruction of the L1 signaling is 2 commands for specifying only the threshold value up or down, there is a possibility that the change instruction cannot be correctly transmitted to the terminal 2 due to a transmission error or the like.

Therefore, the base station transmits the L1 layer command a plurality of times in succession so that the handover threshold change instruction to the terminal 2 can be received correctly (step ST5 d).

As described above, in the method 3, the process in which the base station controller 3 participates in the handover threshold changing process is limited to the minimum. Therefore, communication between the base station and the base station control device 3 can be omitted, and the handover threshold change of the terminal 2 can be performed quickly.

The operation of step ST3d in fig. 22 of the mobile communication system of embodiment 1 will be described in detail using the flowchart shown in fig. 23.

First, the uplink packet transmission management unit 24 in the base station checks the scheduling status of data transmission in the scheduling mode in the own cell (step ST1 e).

Next, the uplink packet transmission managing unit 24 determines whether or not the traffic load of the scheduling mode is appropriate for the allowable limit allocated by the base station control device 3, based on the scheduling status investigated in step ST1e (step ST2 e).

Specifically, the uplink packet transmission management unit 24 determines whether or not the traffic load in the scheduling mode is appropriate based on the number of terminals that notify that data is transmitted in the scheduling mode and the amount of data to be transmitted in data communication.

The uplink packet transmission management unit 24 determines, for example, that the number of terminals in the scheduling mode in the own cell and the amount of data to be transmitted in the data communication are large and the communication conditions (delay requirements and the like) specified by QoS for the data transmission in the scheduling mode are not satisfied, as a state in which the traffic load in the scheduling mode is excessive.

Conversely, a case where the number of terminals in the scheduling mode in the cell and the amount of data to be transmitted in the data communication are small and the communication conditions (delay requirements and the like) specified by the QoS for the data transmission in the scheduling mode are satisfied sufficiently, but the allowable limit for the scheduling mode is hardly used is determined as a state where the traffic load in the scheduling mode is too small.

In the scheduling mode, the terminal 2 in the scheduling mode can be set by repeating the operation using only the radio resource allocated by the uplink packet transmission management unit 24.

However, if the number of terminals 2 in which the scheduling mode is set is large, a delay inevitably occurs in order to transmit data only in the order of the scheduler.

Therefore, in the above-described determination method, whether or not the scheduling mode traffic load is appropriate is determined based on the degree of delay permitted for the data processed by the scheduling mode terminal 2.

As a determination method other than the above, a process of the autonomous mode may be focused as an example. Specifically, the uplink packet transmission management unit 24 estimates the noise increase factor by assuming that the autonomous mode terminal 2 in the own cell performs data transmission at the maximum value of the allowable data rate range notified in advance.

Therefore, when the autonomous mode allowable limit is set according to the noise increase factor, a state in which the current scheduling mode allowable limit needs to be reduced is determined as a state in which the traffic load of the scheduling mode is excessive.

On the contrary, even if the autonomous mode allowable limit is set according to the noise increase factor, the state in which the current scheduling mode allowable limit can be increased is determined as the state in which the scheduling mode traffic load is too small.

In the two determination methods, the state other than the case where the scheduling mode traffic load is large or small is determined as the state where the traffic load is appropriate.

If it is determined in step ST2e that the traffic load is appropriate, the upstream packet transmission managing unit 24 ends the processing shown in fig. 23 and does not notify the terminal 2 either.

If it is determined in step ST2e that the traffic load is excessive, the uplink packet transmission managing unit 24 searches for a terminal 2 having a high autonomous mode transmission frequency in the own cell (step ST3 e). For example, the terminal 2 that has performed the autonomous mode permission data rate notification in advance more than a predetermined number of times is determined as a terminal that transmits in the autonomous mode more frequently.

Next, the upstream packet transmission managing unit 24 determines whether or not the terminal 2 transmitting the excessive frequency in the autonomous mode allows delay in step ST3e (step ST4 e). The decision is made based on a delay amount specified according to the QoS of the data handled by the terminal 2. At this time, if it is determined that the terminal 2 is not allowed to delay, the uplink packet transmission management unit 24 ends the processing shown in fig. 23 and does not perform notification to the terminal 2.

On the other hand, if it is determined that the terminal 2 is permitted to delay, the upstream packet transmission managing unit 24 lowers the switching threshold for the terminal 2, and moves to the process of step ST4d in fig. 22 (step ST5 e).

In this way, if the changed handover threshold is notified by the L1 signaling, the terminal 2 switches the transmission mode according to the threshold and responds to the instruction to the base station.

The uplink packet transmission managing unit 24 in the base station determines whether or not the terminal 2 is switched to the scheduling mode, based on the transmission mode switching response from the terminal 2 (step ST6 e).

At this time, if it is determined that the scheduling mode is switched, the uplink packet transmission management unit 24 estimates a noise increase factor for the new scheduling mode, and increases the noise increase factor limit (noise increase factor limit) of the scheduling mode within the allowable limit range set by the base station control device 3 (step ST7 e).

On the other hand, if it is determined in step ST6e that there is no response to the transmission mode switching instruction from the terminal 2 and the transition to the scheduling mode is not made, the uplink packet transmission managing unit 24 proceeds to the processing of step ST5d in fig. 22 and transmits the changed switching threshold setting to the target terminal 2 by continuing the L1 signaling command (step ST8 e). Thereafter, if there is a response to the transmission mode switching instruction from the terminal 2, the process returns to step ST6 e.

Further, if the uplink packet transmission managing unit 24 determines in step ST2e that the traffic load in the scheduling pattern is small, it searches for a terminal 2 having a low frequency of transmission in the scheduling pattern or a terminal 2 that handles delay-intolerant data among the terminals 2 accommodated in the own cell (step ST9 e).

In step ST9e, when a terminal 2 with a low scheduling mode transmission frequency or a terminal 2 that is not allowed to process delay data is extracted, the uplink packet transmission management unit 24 increases the switching threshold of the terminal 2, and the process proceeds to step ST4d in fig. 22 (step ST10 e).

As described above, if the changed handover threshold value is signaled by L1, the terminal 2 switches the communication mode according to the threshold value and responds to the instruction to the base station.

The uplink packet transmission managing unit 24 determines whether or not the terminal 2 is switched to the autonomous mode, based on the transmission mode switching response from the terminal 2 (step ST11 e).

At this time, if it is judged that the autonomous mode is switched, the uplink packet transmission management unit 24 estimates a noise increase factor for the new autonomous mode, and increases the autonomous mode noise increase factor limit (noise increase factor limit) within the allowable limit range set by the base station control device 3 (step ST12 e).

On the other hand, if it is judged in step ST11e that there is no response from the terminal 2 instructing to switch the transmission mode and that the transition to the autonomous mode is not made, the upstream packet transmission managing unit 24 proceeds to the processing of step ST5d of fig. 22 and transmits the signal to the target terminal 2 by continuing the L1 signaling command for the post-change switching threshold setting (step ST13 e). Thereafter, if there is a response from the terminal 2 to the instruction to switch the transmission mode, it returns to the process from step ST11 e.

As described above, according to the method 3, since the terminal 2 is notified of the change information of the handover threshold value by the physical layer signaling at a higher rate than the rate of the layer 3 message, the handover threshold value can be changed following the change in the traffic volume of the packet communication between the base station and the terminal 2. In addition, according to the method 3, it is also possible to appropriately allocate the allowable limit of the noise increase factor for each transmission mode according to the change of the traffic volume.

In the above-described method 3, the base station uplink packet transmission managing section 24 is described as a configuration for determining the communication mode switching threshold, but the present invention is not limited to this.

For example, the radio resource managing unit 66 in the base station control apparatus 3 may be configured to determine the communication mode switching threshold value based on the QoS information grasped by itself and the current traffic situation obtained from the base station.

In this case, the information specifying the communication mode switching threshold may be notified from the base station control apparatus 3 to the base station, and notified from the base station to the terminal 2 in the 3 rd method.

In addition, in the above-described embodiment, although the processing in which the base station side configuration including the base station control apparatus 3 determines the switching threshold of the terminal 2 and the terminal 2 switches the transmission mode according to the threshold specified by the base station is described, the present invention is not limited to the above-described configuration.

For example, the base station side configuration including the base station control apparatus 3 may determine a transmission mode to be switched based on a switching threshold of the terminal 2, and the terminal 2 may switch the transmission mode based on an instruction from the base station side.

Next, with respect to this structure, description is made with respect to embodiments respectively applied to the cases of the above-described 1 st to 3 rd methods.

First, the operation of the case of using the method 1 will be described in detail with reference to the flowchart shown in fig. 24, in which the base station side determines the transmission mode to be switched, and the terminal 2 switches the transmission mode in accordance with an instruction from the base station side.

The processing from step ST1a to step ST8a is the same as that in fig. 16, and therefore, the description is omitted. In any of the steps from step ST6a to step ST8a, the radio resource managing unit 66 in the base station control apparatus 3 notifies the base station of the handover threshold if the threshold is determined.

The uplink packet transmission management unit 24 of the base station compares the threshold value notified from the base station control device 3 with the transmission data amount notified in advance by each terminal 2 in the own cell, and thereby determines the transmission mode to be set in the terminal 2 (step ST9 a).

For example, when the amount of transmission data notified in advance exceeds the threshold, it is determined that the scheduling mode should be set, and conversely, the autonomous mode is selected.

If the transmission mode is determined in step ST9a, the upstream packet transmission managing unit 24 instructs the report information transmitting unit 28 to perform signaling instructing switching to the transmission mode for each terminal 2 using the report information (step ST10 a).

Specifically, in the process of step ST11 in fig. 15, information for specifying the transmission mode specified by the base station side is transmitted instead of the information including the changed handover threshold.

In this way, not only the switching threshold but also the transmission mode to be switched can be determined, and the terminal 2 can know which transmission mode to switch to.

Therefore, when the terminal 2 needs to switch the transmission mode according to the threshold value specified by the base station, the terminal 2 can omit the response signaling for notifying the base station of switching the transmission mode.

Next, the operation in the case where the configuration for the base station side to determine the transmission mode to be switched and the terminal 2 to switch the transmission mode in accordance with the instruction from the base station side is applied to the method 2 will be described in detail with reference to the flowchart shown in fig. 25.

The processing from step ST1c to step ST11c is the same as that in fig. 20, and therefore, the description thereof is omitted. The radio resource managing unit 66 in the base station control apparatus 3 notifies the base station of the handover threshold value if the threshold value is determined in any one of step ST8c, step ST9c, step ST10c and step ST11 c.

The uplink packet transmission management unit 24 in the base station compares the threshold value notified from the base station control device 3 with the transmission data amount notified in advance from the terminal 2 to which the transmission mode is to be switched, and thereby specifies the transmission mode to be set in the terminal 2 (step ST12 c).

When the transmission mode is determined in step ST12c, the uplink packet transmission managing section 24 instructs the downlink individual channel transmitting section 29 or the downlink common channel transmitting section 34 to perform signaling for switching the transmission mode to the target terminal 2 using the individual channel or the common channel (step ST13 a).

Specifically, in the process of step ST11b in fig. 19, not only the information including the changed switching threshold but also information for specifying the transmission mode specified by the base station side may be transmitted. In this case, the processing of step ST13b and step ST14b in fig. 19 may be omitted.

In this way, the base station side can determine not only the switching threshold but also the transmission mode to be switched, and the terminal 2 can know to which transmission mode to switch.

Therefore, when it is necessary for the terminal 2 to switch the transmission mode according to the threshold value specified by the base station, the terminal 2 can omit the response signaling for the terminal 2 to notify the base station of the transmission mode to be switched.

In addition, although the above description has been made of the configuration in which the radio resource management unit 66 in the base station control apparatus 3 specifies the communication mode switching threshold, the present invention is not limited to this.

For example, since the base station obtains QoS information and the like from the base station control device 3, the uplink packet communication managing unit 24 in the base station may be configured to determine the communication mode switching threshold.

By doing so, in the process of determining the communication mode switching threshold, it is possible to reduce the processes in which the base station control apparatus 3 participates, and to suppress an increase in the number of times of signaling between the base station and the base station control apparatus 3.

The base station may be configured to determine the transmission mode by adding a change according to the current traffic situation to the threshold value determined on the base station control device 3 side and comparing the changed threshold value with the transmission data amount of the terminal 2 notified in advance.

That is, the present invention also includes a configuration in which the base station and the base station control device 3 determine the threshold value in common. In this case, the packet communication management unit 24 can be considered as a base station side configuration for changing the threshold value notified from the base station control device 3.

Next, the configuration in which the base station side determines the transmission mode to be switched and the terminal 2 switches the transmission mode in accordance with the instruction of the base station side, using the flowchart shown in fig. 26, will be described in detail with respect to the operation in the case of using the method of the 3 rd embodiment.

First, since the processing from step ST1e to step ST4e is the same as that in fig. 23, the description is omitted. If it is judged in step ST4e that the terminal 2 is allowed to delay, the upstream packet transmission managing unit 24 down-regulates the switching threshold value for the terminal 2 (step ST5 e-1).

Next, if the upstream packet transmission managing unit 24 determines the communication mode that should be set in the terminal 2 by comparing the threshold determined in step ST5e-1 with the transmission data amount notified in advance by the terminal 2 found in step ST4e (step ST5 e-2).

Next, the uplink packet transmission managing unit 24 signals information for specifying the transmission mode to be set in the terminal 2 as the aforementioned L1 signal, and proceeds to the processing of step ST4d in fig. 22 (step ST5 e-3).

The following processing from step ST6e to step ST8e is the same as fig. 23, and therefore, the description thereof is omitted.

When extracting a terminal 2 transmitting a small number of frequencies in the scheduling mode or a terminal 2 processing delay-intolerant data in step ST9e, the uplink packet transmission management unit 24 increases the switch threshold value for the terminal 2 (step ST10 e-1).

Next, the upstream packet transmission managing unit 24 determines the transmission mode that should be set in the terminal 2 by comparing the threshold determined in step ST10e-1 with the transmission data amount notified in advance by the terminal 2 found in step ST9e (step ST10 e-2).

Next, the uplink packet transmission managing unit 24 signals information for specifying the transmission mode to be set in the terminal 2 as the aforementioned L1 signal, and proceeds to the processing of step ST4d in fig. 22 (step ST10 e-3).

The processing from step ST11e to step ST13e is the same as that in fig. 23, and therefore, the description thereof is omitted.

In addition, in the above-described method 3, although the configuration in which the uplink packet transmission management unit 24 in the base station determines the communication mode switching threshold value has been described, the present invention is not limited to this.

For example, the radio resource management unit 66 in the base station control apparatus 3 may be configured to determine the communication mode switching based on the QoS information grasped by itself and the current traffic situation obtained from the base station.

In this case, information for specifying the communication mode switching threshold is notified from the base station control apparatus 3 to the base station, and is notified from the base station to the terminal 2 in the 3 rd method.

Further, in the above description, the uplink packet transmission management unit 24 in the base station has been described as a configuration for determining the communication mode, but the present invention is not limited to this.

For example, the radio resource management unit 66 in the base station control apparatus 3 may be configured to determine the transmission mode to be set in the terminal 2, based on the QoS information grasped by the terminal 2 and the transmission data amount of the data communication performed by the terminal 2 via the base station.

In this case, in the processing of steps ST10 and ST11 in fig. 15 and steps ST10b and ST11b in fig. 19, information for specifying the transmission mode determined on the base station side is transmitted instead of the information including the changed switching threshold.

The transmission mode determined by the radio resource management unit 66 is notified to the base station by the base station control device 3, and then the base station notifies the terminal 2 by the above-described methods.

As described above, according to embodiment 1, while the transmission mode suitable for terminal 2 can be set according to the operating state of the base station, it is also possible to appropriately allocate the allowable limits for various transmission modes to the allowable limits of the noise increase factor set in the base station.

In addition, in the case where the switching threshold is set for each terminal 2, by considering QoS of data handled by the terminal 2, it is possible to equalize various transmission modes and effectively utilize radio resources by reflecting data transmission demands of each terminal.

In addition, in the above-described embodiment, the base station is signaled by the terminal 2, and the structure of the base station is described as indicating acquisition of transmission buffer information for determining switching of the transmission mode of the terminal 2.

Here, if the frequency of the terminal 2 is not changed according to the delay tolerance of processing data by the terminal 2, there is a possibility that the signaling of the transmission buffer information of the base station by the terminal 2 cannot satisfy the delay request also as the transmission mode switching.

For example, if the signaling frequency of the transmission buffer information reaching the base station from the terminal 2 is small, the structure on the base station side becomes slow in grasping the current transmission data buffer status of the terminal 2.

In this case, the process of switching the terminal 2 to the scheduling mode or the autonomous mode becomes slow, and even there is a possibility that the delay requirement of the data communication of the terminal 2 cannot be satisfied.

Therefore, the mobile communication terminal 2 can change the frequency of the transmission buffer information signaling to the base station according to the delay requirement set in the data communication handled by itself.

For example, when the signaling is performed at a predetermined cycle for the terminals 2 to the base station, the signaling may be performed at a shorter cycle for the terminal 2 performing data communication with a relatively strict delay requirement, and the signaling may be performed at a longer cycle for the terminal 2 performing data communication with a relatively slow delay requirement. The setting of these signaling periods may be performed separately for each terminal according to the delay tolerance of the data communication to be performed.

If the generation process of the above signaling cycle is described, control information called a transmission timing basic SFN (system frame number) can be set in the P-ccpch (bch). The uplink packet transmission management unit 24 in the base station determines the signaling cycle of the transmission buffer information by the terminal 2 based on the QoS parameter and the like obtained from the base station control device 3.

The method of setting the signaling cycle in the terminal 2 is similar to the signaling of the handover threshold, and the report information using the 1 st method (common assignment to the group of terminals 2), the individual or common channel using the 2 nd method (individual assignment to the terminal 2), and the physical layer signaling using the 3 rd method can be considered.

In the mobile communication terminal 2, if information on the above-described signaling cycle is received from the base station, signals set in the respective data channels are demodulated by the despreading demodulation unit 46 as described using fig. 11. The protocol processing unit 56 obtains information related to the above-described signaling period from the signal demodulated by the despreading demodulation unit 46.

Next, the protocol processing section 56 sets a period obtained from the information on the signaling period in the buffer status transmitting section 55 as a transmission period of the UL-SICCH for notifying the base station of the status of the transmission data buffer 58. Further, the mobile communication terminal 2 synchronizes timing to transmit data with the base station based on the SFN value set in the P-ccpch (bch).

As a method of more efficiently specifying the above signaling period, grouping may be performed. Specifically, for example, using a QoS class, the terminals 2 belonging to the session type class and the flow class perform grouping according to the maximum delay amount that can be tolerated by the QoS class, and determine the above-described signaling period.

On the other hand, for terminals 2 belonging to other than the above-described QoS class, a longer period may be set than for terminals 2 belonging to, for example, the session type class and the flow class. In this method, there is an advantage that the amount of communication mode interference can be managed for each group of terminals 2 according to the QoS class.

Next, an application example of a case where the signaling of the transmission buffer information is performed when the state of the mobile communication terminal 2 reaches a predetermined condition, instead of the signaling being performed periodically as described above, will be described.

As the predetermined condition, when a certain amount of transmission data is accumulated in the uplink packet communication transmission data buffer 58 of the terminal 2, the terminal 2 may perform the transmission buffer information signaling to the base station.

In this case, the signaling of the transmission buffer information is not performed until a certain amount of transmission data is accumulated in the transmission data buffer 58. However, depending on the data handled by the terminal 2, if the transmission data is not waited for to accumulate in a certain amount in the transmission data buffer 58, there is a case where the above signaling should be executed.

For example, although the data amount of the response signal from the application program executed by the terminal 2 via the internet is relatively small, the existence itself should be notified to the base station as early as possible.

Therefore, the terminal 2 may be configured to wait until the amount of data stored in the transmission data buffer reaches a certain amount when processing data having a strict delay requirement by setting a time for specifying the signaling cycle, and to execute the signaling if the time elapses.

The time assignment may be considered to be a case of signaling explicitly indicated by a configuration on the base station side or a case of setting by the terminal 2 itself.

First, with reference to fig. 10 and 11, description will be made of an operation in a case where the above time is specified by signaling explicitly shown in the base station side structure. Here, the uplink packet transmission management unit 51 in the terminal 2 has the above-described timer function.

The base station control apparatus 3 generates a cycle for specifying a period corresponding to a QoS parameter using the QoS parameter relating to data communication by the terminal 2 as a time setting target.

Next, the base station acquires the timing information from the base station control device 3, and transmits the timing information as information of an individual channel to the terminal 2 by the downlink individual channel transmitting unit 29.

In the terminal 2, the downlink individual channel receiving section 63 receives the information of the individual channel and transmits the information to the protocol processing section 56. The protocol processing unit 56 reads out timing information from the information of the individual channel, and transmits the timing information to the uplink packet transmission management unit 51.

The uplink packet transmission managing section 51 sets a time based on the time information, and executes the signaling of the transmission buffer information by the timing instruction buffer status transmitting section 55.

Next, a process of autonomously managing time on the terminal 2 side will be described.

First, the uplink packet transmission management unit 51 determines a timing value based on QoS information grasped by itself and the presence or absence of past transmission. If the time reaches the count value, the uplink packet transmission management unit 51 instructs the buffer status transmission unit 55 to perform the above signaling of the transmission buffer information.

As a time specification method for more efficiently executing the above signaling, for example, it is conceivable that the base station control device 3 and the uplink packet transmission management unit 51 set a time by comparing the allowable delay amounts of the session type class and the stream class.

In addition, in the interactive level and the background level, the base station control apparatus 3 and the uplink packet transmission management unit 51 designate a shorter timing time than the terminal 2 which has the history of performing communication in the past to the terminal 2 which has performed communication for the first time, and further gradually lengthen the designated timing time as the communication interval becomes vacant.

Thus, the number of times of signaling for transmitting data buffer information to the base station can be flexibly set by combining the number of times of signaling for data communication. For example, for the terminal 2 performing data communication of a smaller traffic amount, the number of times of signaling can be more effectively controlled by making the above signaling interval free.

In addition, a method of performing signaling in the above cycle and a method of using timing may be used simultaneously. For example, the terminal 2 that performs data communication for which the delay amount needs to be set strictly may periodically perform signaling for transmitting data buffer information to the base station, and the terminal 2 that performs data communication for which the delay amount is not set strictly may perform the signaling at intervals designated by the timing.

More specifically, in the terminal 2 that handles data communication belonging to the session type class and the stream class, the signaling cycle is set according to the maximum delay amount allowed by the QoS class. In addition, in the terminal 2 which handles data communication belonging to the interactive level and the background level, signaling is executed based on QoS information grasped by itself and the time set by whether or not there is a past transmission.

In this way, the base station side can suppress an increase in the signaling of the transmission data buffer information from the terminal 2 more than necessary while managing the amount of data communication interference by the terminal 2. Thus, the signaling can be performed more efficiently as a whole of the mobile communication system.

Industrial applicability

As described above, the communication mode switching method according to the present invention can be used in a mobile communication terminal such as a mobile phone supporting uplink packet communication, a base station, and a base station control device.

Claims (1)

1. A mobile communication system includes a mobile communication terminal, a base station that performs wireless communication with the terminal, and a base station control device that controls the base station,

the mobile communication system is characterized in that:

the terminal includes:

a terminal buffer for storing uplink data for transmission to the base station;

a buffer status information transmitting unit for transmitting terminal buffer status information indicating a status of the terminal buffer to the base station; and

a data transmission unit configured to transmit data to the base station in accordance with an instruction on an uplink radio resource by the base station,

the base station includes:

an interference amount measuring unit configured to measure an interference amount associated with the received signal;

an interference amount notification unit configured to notify the base station controller of the interference amount measured by the interference amount measurement unit; and

an uplink radio resource indicator unit for receiving the terminal buffer status information, performing scheduling, and indicating an uplink radio resource to the terminal,

the base station control device includes:

and a maximum interference amount indicating unit configured to indicate a maximum interference amount that should not be exceeded as a result of scheduling to the base station.