CN1989781A - Wireless communication terminal, program, and communication method - Google Patents

Abstract

A wireless communication terminal comprising: a switching section for switching between the first communication system and the second communication system in which the transmission rate upper limit value changes; a receiving section for receiving information indicating an upper limit value of a transmission rate in the first communication system from the base station; a comparing section for comparing the upper limit value received by the receiving section with a predetermined reference value at the start of communication or during communication with a base station in the first communication system; and a control section for performing handover control of the handover section so as to perform communication in the second communication system when the upper limit value is lower than the reference value as a result of the comparison by the comparison section.

Description

Wireless communication terminal, program and communication method

technical field

The present invention relates to a wireless communication terminal, a program, and a communication method that perform communication by switching a plurality of communication systems.

The present invention also relates to a wireless communication terminal, a program, and a communication method in a communication system that changes a transmission rate according to a congestion state of a base station.

Background technique

A wireless communication terminal capable of switching between two or more communication systems in order to communicate with a base station is known.

For example, such a wireless communication terminal capable of performing communication in a plurality of communication systems is known to be capable of switching between a CDMA2000 1x system mainly used for voice communication and a CDMA2000 1xEVDO system used only for data communication to use a common antenna A wireless communication terminal that performs communication (hereinafter referred to as a dual system) (for example, refer to Patent Document 1).

The CDMA2000 1xEVDO system is a next-generation high-speed wireless communication system, which was standardized in ARIB's Std.T-64 IS-2000 C.S.0024 "CDMA2000 High Rate Packet Data AirInterface Specification" as a standardization of the HDR (High Data Rate) system , an extension system of the CDMA2000 1x system provided by U.S.A. and merged with QUALCOMM. The CDMA2000 1xEVDO system is designed to expand the CDMAOne system (ARIBT-53 in Japan, North America, South Korea, etc. EIA/TIA/IS-95) currently provided by KDDI CORPORATION in Japan, and to further develop the CDMA2000 1x system in data communication. Improved transfer rate, which is compatible with third generation systems (3G).

"EV" of CDMA2000 1xEVDO means evolution, and "DO" means data only (refer to Patent Document 2).

In a communication system using such a dual system wireless communication terminal, the CDMA2000 1xEVDO system can change the upper limit of the transmission rate according to the congestion state of the base station.

Wireless communication terminals in the communication system perform communication based on the upper limit.

For example, for the upper limit value of the transmission rate of communication (uplink communication) from the wireless communication terminal to the base station, the lowest speed is selected at the start of communication. Thereafter, the wireless communication terminal changes the transmission rate based on instruction information indicating to increase or decrease the transmission rate upper limit value transmitted from the base station every predetermined time.

In addition to the information transmitted from the base station at every predetermined timing, the base station may transmit emergency information for limiting the upper limit value of the transmission rate to the wireless communication terminal.

In this case, the wireless communication terminal changes the transmission rate to a limit value based on the received emergency information.

Such urgent information is transmitted in a situation where the base station may fail if the transmission rate is not reduced, for example, when a large number of wireless communication terminals are connected and concentrated to one base station, almost up to the connection allowance limit of the base station (the base station is in a congested state) in the case of.

Therefore, in the CDMA2000 1xEVDO system, at least the upper limit of the transmission rate in uplink communication can be changed.

Also, in a dual system wireless communication terminal, if the radio wave state between the wireless communication terminal and the base station becomes poor during communication in the CDMA2000 1xEVDO system, the antenna can be switched, thereby using CDMA2000 1x which is another communication system system to communicate.

Therefore, if a wireless communication terminal determines that satisfactory communication cannot be performed using the CDMA2000 1xEVDO system due to deterioration of the radio wave state, it can switch the CDMA2000 1xEVDO system to the CDMA2000 1x system for continued communication.

The communication switch from CDMA2000 1xEVDO system to CDMA2000 1x system is called "hand down (hard handover between different carriers in the same cell)".

In a wireless communication system including a wireless communication terminal and a base station such as a cellular communication system, a technique has been proposed in which a base station to which a wireless system terminal is connected to perform communication (hereinafter referred to as a "connected base station"), and Each of one or more base stations (hereinafter referred to as "peripheral base stations") that are adjacent to the connected base station as handover destination candidates instructs to increase or decrease the transmission rate based on the degree of congestion of the base station, and the wireless communication terminal To execute communication control instructions, change the transmission rate.

In this specification, handover means the handover of connecting base stations.

In communication control, if all of the connection base station and the surrounding base stations which are handover destination candidates are all low in congestion and all the base stations instruct to increase the transmission rate, the wireless communication terminal operates to increase the transmission rate; on the other hand, if One of the base stations has a high degree of congestion and instructs to reduce the transmission rate, and the wireless communication terminal operates to reduce the transmission rate.

As the control is performed in this way, the transmission rate matches the transmission rate of the congested base station among the connecting base station and all the surrounding base stations, when handover is performed from a base station with a low degree of congestion and a high transmission rate to a base station with a high degree of congestion and a low transmission rate , it can prevent the occurrence of errors such as packet loss due to the rapid decrease of the transmission rate.

Patent Document 1: Refer to JP-A-2003-298762

Patent Document 2: Refer to JP-A-2002-300644

Contents of the invention

The problem to be solved by the present invention

In the dual system wireless communication terminal as described above, based on instruction information for raising or lowering the transmission rate transmitted from the base station at every predetermined timing, and emergency information for limiting the upper limit value of the transmission rate transmitted from the base station Change the transfer rate. In this case, depending on the situation of the base station, the transmission rate may not increase from the communication start time (minimum speed), or the transmission rate may be lowered according to the instruction of the upper limit value from the base station, and the transmission rate may remain at that status without improvement.

Specifically, when a base station suddenly becomes congested, instruction information to "reduce" the transmission rate may be continuously and repeatedly transmitted from the base station at every predetermined timing, or a connection with a heavily congested base station may be established and continuous transmission may be performed for Information used to limit the transmission rate, etc.

In these cases, communication continues at a low speed (for example, at the lowest speed), and therefore, if switching from the CDMA2000 1xEVDO system to the CDMA2000 1x system as another communication system to perform communication with a CDMA2000 1x base station, the performance of the transmission rate is improved The possibility is high. However, as described above, hand down depends on the state of radio waves between the wireless communication terminal and the base station, so that hand down cannot be achieved at the required time. Therefore, the communication throughput in the CDMA2000 1xEVDO system is reduced; this is a problem.

Especially in the case where it is impossible to move to another cell, so that handover cannot be considered, but it is necessary to preferably increase the transmission rate, for example, when the user puts the wireless communication terminal on the table, etc., and receives a real-time property This becomes even more of a problem when streaming video bitstreams.

Accordingly, an object of the present invention is to enhance the throughput of a wireless communication terminal capable of performing communication in a plurality of communication systems.

means of solving problems

The essence of the present invention for solving the above-mentioned problems is described in (1) to (30) below:

(1) A wireless communication terminal, comprising:

a switching section for switching between a first communication system whose transmission rate upper limit value is changed and a second communication system;

a receiving section configured to receive information indicating a transmission rate upper limit value in the first communication system from the base station;

a comparing section for comparing the upper limit value received by the receiving section with a predetermined reference value at the start of communication or during communication with a base station in the first communication system; and

A control section for performing switching control of the switching section to perform communication in the second communication system when the result of the comparison by the comparing section is that the upper limit value is lower than the reference value.

(2) A wireless communication terminal, comprising:

a switching section for switching between a first communication system whose transmission rate upper limit value is changed and a second communication system;

a receiving section for receiving instruction information from the base station at each predetermined timing, indicating to change the upper limit value of the transmission rate in the first communication system;

a determination section for determining whether instruction information for instructing lowering of the transmission rate upper limit value is successively received a predetermined number of times or more during communication with a base station in the first communication system; and

a control section for executing switching control of the switching section so as to execute the second Communication in the second communication system.

(3) In the wireless communication terminal, only when the upper limit value of the transmission rate in the first communication system is lower than a predetermined reference value, the control section determines that the result of the determination by the determination section is successively received equal to or more than a predetermined number of times. Upon arrival of instruction information for instructing lowering of the transmission rate upper limit value, switching control of the switching section is performed.

(4) In the wireless communication terminal, the reference value is a value at which it is expected that the transmission rate will increase when communication is performed in the second communication system instead of the first communication system.

(5) A wireless communication terminal, comprising:

a derivation part for deriving the remaining amount of data to be transmitted in the first communication system,

Wherein only when the amount of remaining data derived by the deriving section is greater than a predetermined amount, the control section executes switching control to switch to the second communication system when the result of the comparison by the comparing section is that the upper limit value is lower than the reference value.

(6) A wireless communication terminal, comprising:

a derivation part for deriving the remaining amount of data to be transmitted in the first communication system,

wherein only when the amount of remaining data derived by the deriving portion is greater than a predetermined amount, the control portion is determined by the determining portion as a result of successively receiving instructions for instructing lowering of the transmission rate upper limit value a predetermined number of times When the message is received, switching control to switch to the second communication system is performed.

(7) A program for use in a wireless communication terminal in which communication is performed by switching between a first communication system in which a transmission rate upper limit value is changed and a second communication system, the program include:

The first process is used to receive information from the base station indicating the upper limit value of the transmission rate in the first communication system;

a second process for comparing the upper limit value received by the receiving section with a predetermined reference value at the start of communication or during communication with the base station in the first communication system; and

The third process is for switching from the first communication system to the second communication system when the comparison result obtained by the second process is that the upper limit value is lower than the reference value.

(8) A program for use in a wireless communication terminal in which communication is performed by switching between a first communication system in which a transmission rate upper limit value is changed and a second communication system, the program include:

A first process for receiving instruction information from the base station at each predetermined timing, indicating to change the upper limit value of the transmission rate in the first communication system;

A second process for determining whether, during communication with a base station in the first communication system, instruction information for instructing lowering of the upper limit value of the transmission rate is successively received a predetermined number of times or more; and

A third process for switching from the first communication system to the second communication system when the determination result obtained by the second process is that instruction information for instructing to lower the upper limit value of the transmission rate has been successively received a predetermined number of times or more. Communication Systems.

(9) In the program, in the third process, only when the transmission rate upper limit value in the first communication system is lower than a predetermined reference value, only when the determination result obtained by the second process is equal to or more than the predetermined Switching from the first communication system to the second communication system is performed when the instruction information for instructing to lower the upper limit value of the transmission rate is successively received.

(10) In the program, the reference value is a value at which the transmission rate is expected to increase when communication is performed in the second communication system instead of the first communication system.

(11) The procedure includes:

a fourth procedure for deriving the remaining amount of data to be transmitted in the first communication system,

In the third process, only when the remaining data amount derived by the fourth process is greater than the predetermined amount, and only when the comparison result by the second process is that the upper limit value is lower than the reference value, the transfer from the first communication system to the second Communication system switching.

(12) The procedure includes:

a fourth procedure for deriving the remaining amount of data to be transmitted in the first communication system,

Wherein only when the remaining data amount derived by the fourth process is greater than a predetermined amount, the determination result obtained by the second process is that instruction information for instructing to lower the upper limit value of the transmission rate is successively received a number of times equal to or more than a predetermined number of times , switching from the first communication system to the second communication system is performed.

(13) A communication method for performing communication in a wireless communication terminal by switching between a first communication system in which a transmission rate upper limit value is changed and a second communication system, the communication method comprising:

receiving information indicating a transmission rate upper limit value in the first communication system from the base station;

comparing the upper limit value received from the base station with a predetermined reference value at the start of communication or during communication with the base station in the first communication system; and

When the comparison result is that the upper limit value is lower than the reference value, switch from the first communication system to the second communication system.

(14) A communication method for performing communication in a wireless communication terminal by switching between a first communication system and a second communication system in which a transmission rate upper limit value changes, the communication method comprising:

receiving instruction information from the base station at every predetermined timing indicating to change the transmission rate upper limit value in the first communication system;

determining whether instruction information for instructing lowering of the transmission rate upper limit value is successively received a predetermined number of times or more during communication with a base station in the first communication system; and

When the determination result is that instruction information for instructing to lower the transmission rate has been successively received a predetermined number of times or more, switching from the first communication system to the second communication system.

(15) In the communication method, only when the upper limit value of the transmission rate in the first communication system is lower than a predetermined reference value, when the determination result is successively received equal to or more than a predetermined number of times for instructing to reduce the transmission When the instruction information of the rate is received, switching from the first communication system to the second communication system is performed.

(16) In the communication method, the reference value is a value at which the transmission rate is expected to increase when communication is performed in the second communication system instead of the first communication system.

(17) The communication method includes:

deriving a remaining amount of data to be transmitted in the first communication system when the comparison result is that the upper limit value is lower than the reference value,

Wherein, switching from the first communication system to the second communication system is performed only when the derived remaining data amount is greater than a predetermined amount.

(18) The communication method includes:

deriving the remaining amount of data to be transmitted in the first communication system when the determination result is that instruction information for instructing to lower the transmission rate has been successively received equal to or more than a predetermined number of times,

Wherein, switching from the first communication system to the second communication system is performed only when the derived remaining data amount is greater than a predetermined amount.

(19) A wireless communication terminal connected to a connecting base station holding information of peripheral base stations as candidate handover destinations, the wireless communication terminal comprising:

The receiving part is used to receive instruction information from surrounding base stations indicating to change the upper limit value of the transmission rate;

a determining part, configured to determine whether the instruction information received by the receiving part includes instruction information indicating to lower the upper limit value of the transmission rate;

a generating section for generating a signal for controlling peripheral base station information when the determination result obtained by the determining section includes instruction information indicating to lower the upper limit value of the transmission rate; and

A transmitting section for transmitting the signal generated by the generating section to the connecting base station.

(20) In the wireless communication terminal, the signal for controlling surrounding base station information is information including a base station that transmits instruction information for instructing lowering of the transmission rate upper limit value removed from the surrounding base station information.

(21) In the wireless communication terminal, the signal for controlling peripheral base station information is a value indicating communication quality between a base station transmitting instruction information indicating lowering of the transmission rate upper limit value and the wireless communication terminal, and

Said value is lower than a predetermined reference value.

(22) The wireless communication terminal includes:

The export section, which is used to export the data volume of the data to be transferred,

Only when the amount of data derived by the deriving part is greater than the predetermined value, the transmitting part transmits to the connecting base station when the determination result obtained by the determining part includes instruction information indicating to lower the upper limit of the transmission rate information signal.

(23) A program for use by a wireless communication terminal connected to a connected base station holding information of peripheral base stations that are candidate handover destinations, the program comprising:

The first process is used to receive instruction information from surrounding base stations indicating to change the upper limit value of the transmission rate;

A second process for determining whether instruction information indicating to lower the upper limit value of the transmission rate is included in the instruction information received by the receiving section; and

A third process for transmitting a signal for controlling peripheral base station information to the connected base station when the determination result obtained by the determination section includes instruction information indicating lowering of the upper limit value of the transmission rate.

(24) In the program, the signal for controlling the surrounding base station information includes removing information of a base station that transmits instruction information indicating lowering of the transmission rate upper limit value from the surrounding base station information.

(25) In the program, the signal for controlling the surrounding base station information is a value indicating the communication quality between the base station and the wireless communication terminal transmitting instruction information indicating lowering of the upper limit value of the transmission rate, and

Said value is lower than a predetermined reference value.

(26) The procedure includes:

The fourth part, used to derive the data volume of the data to be transferred,

In the third process, only when the remaining data amount derived by the fourth process is greater than the predetermined value, when the determination result obtained by the second part includes instruction information indicating to reduce the upper limit value of the transmission rate, the transmission rate is sent to the connecting base station. Transmits a signal for controlling the information of surrounding base stations.

(27) A communication method for a wireless communication terminal connected to a connecting base station holding information of peripheral base stations that are candidate handover destinations, the communication method comprising:

receiving instruction information from surrounding base stations indicating to change the upper limit value of the transmission rate;

determining whether instruction information for lowering the transmission rate upper limit value is included in the instruction information received by the receiving section; and

When the determination result obtained by the determination section includes instruction information instructing to lower the transmission rate upper limit value, a signal for controlling peripheral base station information is transmitted to the connected base station.

(28) In the communication method, the signal for controlling the surrounding base station information includes removing, from the surrounding base station information, information of a base station that transmits instruction information indicating lowering of the transmission rate upper limit value.

(29) In the communication method, the signal for controlling peripheral base station information is a value indicating communication quality between a base station transmitting instruction information indicating lowering of a transmission rate upper limit value and a wireless communication terminal, and

Said value is lower than a predetermined reference value.

(30) The communication method according to claim 27 comprising:

When the determination result includes instruction information indicating to reduce the upper limit value of the transmission rate, deriving the data amount of the data to be transmitted,

Only when the amount of derived data is greater than a predetermined value, the signal for controlling the information of the surrounding base stations is transmitted to the connecting base station.

Advantages of the invention

According to the configurations in (1) to (30) above, the throughput of a wireless communication terminal capable of performing communication in a plurality of communication systems can be enhanced.

Description of drawings

Fig. 1 is a block diagram of the wireless communication terminal configuration of the first embodiment of the present invention;

FIG. 2 is a table showing the relationship between the transmission rate change and the threshold α in the first embodiment of the present invention;

Fig. 3 is the flowchart of transmission rate change in the first embodiment of the present invention;

Fig. 4 is a flow chart showing the hand down process in the first embodiment of the present invention;

Fig. 5 is a sequence diagram showing the hand down process in the first embodiment of the present invention;

Fig. 6 is a flow chart showing the handdown process in the second embodiment of the present invention;

Fig. 7 is a flow chart showing the hand down process in the third embodiment of the present invention;

Fig. 8 is a flow chart showing the hand down process in the fourth embodiment of the present invention;

Fig. 9 is a sequence diagram showing the hand down process in the fourth embodiment of the present invention;

Fig. 10 is a flow chart showing the hand down process in the fifth embodiment of the present invention;

Fig. 11 is a block diagram of the wireless communication terminal configuration of the sixth embodiment of the present invention;

12 is a schematic representation showing the relationship between the transmission rate change and the base station in the Activeset of the sixth embodiment of the present invention;

FIG. 13 is a schematic representation showing time-based transmission rate changes in the sixth embodiment of the present invention;

Fig. 14 is a flowchart of uplink data transmission time in the sixth embodiment of the present invention;

FIG. 15 is a sequence diagram of uplink data transmission time in the sixth embodiment of the present invention;

FIG. 16 is a flow chart of uplink data transmission time in the seventh embodiment of the present invention;

Fig. 17 is a sequence diagram of uplink data transmission time in the seventh embodiment of the present invention.

Description of reference numbers

10 antennas

20 1xRF section

30 DO RF part

40 RF control section

50 system control part

60 system storage section

100A, 100B, 100a, 100b, 100c, 101 base station

200 wireless communication terminals

Detailed ways

A first embodiment of the present invention will be discussed below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a wireless communication terminal 200 of the present embodiment.

The wireless communication terminal (mobile phone terminal) 200 of this embodiment is capable of switching between the cdma2000 1x communication system (hereinafter referred to as "1x system") and the 1xEVDO communication system (hereinafter referred to as "DO system") to use shared The antenna 10 serves as a wireless communication terminal that performs communication with the DO system base station 100A or the 1x system base station 100B.

The base station 100A performs DO system communication with the wireless communication terminal 200 , and the base station 100B performs 1x system communication with the wireless communication terminal 200 .

The antenna 10 converts radio frequency signals from the 1xRF section 20 or the DO RF section 30 into radio waves, transmits radio waves to the base stations 100A and 100B, receives radio waves from the base stations 100A and 100B, and transmits radio waves to the 1xRF section 20 as radio frequency signals or DORF section 30.

The 1xRF part 20 converts data or voice signals transmitted in the 1x system into radio frequency signals and transmits the radio frequency signals to the antenna 10 . The 1xRF section 20 also converts the radio frequency signal transmitted from the antenna 10 into a data signal or a voice signal.

The DO RF section 30 converts data transmitted in the DO system into a radio frequency signal, and transmits the radio frequency signal to the antenna 10.

The DO RF section 30 also converts radio frequency signals transmitted from the antenna 10 into data signals.

The 1xRF section 20 or the DO RF section 30 functions as a receiving section via the antenna 10.

The RF control section 40 is a control section for controlling communication of two systems, the DO system and the 1x system, and functions as a switching section described later.

The system control section 50 is a control section for performing centralized control of each section of the wireless communication terminal 200, and functions as a comparison section, a control section, and a derivation section described later.

The system storage section 60 is realized by a memory such as a RAM, and stores application programs, temporary data, and the like.

The change of the transmission rate upper limit value of the wireless communication terminal of the present embodiment in DO system data communication will be discussed below with reference to FIGS. 2 and 3 .

First, in the uplink communication of the DO system, the upper limit of the transmission rate is classified into five levels: 9.6kbps, 19.2kbps, 38.4kbps, 76.8kbps and 153.6kbps.

When the wireless communication terminal 200 starts the uplink communication with the base station 100A, the wireless communication terminal first starts communication at the lowest transmission rate (9.6 kbps), and then the wireless communication terminal 200 receives a signal transmitted from the base station 100A at every predetermined timing, which is increased or decreased. Command information "RABit" (reverse active bit) of the upper limit value of the transmission rate, and adjust the transmission rate.

RABit changes according to the congestion state of base station 100A to which wireless communication terminal 200 is connected, and the congestion state of neighboring base stations regarded by wireless communication terminal 200 as handover targets of slave base station 100A.

The congestion of the base station means a case where a large number of wireless communication terminals are connected to the base station in a concentrated manner, a case where congestion occurs in a communication line, and the like.

If there is no congested base station, that is, if the transmission rate can be increased, RABit is set to "0".

RABit is set to "1" if there are one or more congested base stations, ie if increasing the transmission rate is not preferred.

FIG. 3 is a flowchart of transmission rate change performed by the system control section 50 of the wireless communication terminal 200. As shown in FIG.

When the wireless communication terminal 200 starts uplink communication in the DO system, the wireless communication terminal first starts communication at the lowest transmission rate (9.6 kbps).

Next, when the antenna 10 receives the RABit from the base station 100A, it is determined whether the RABit is set to "1" (step 1001). If it is determined that RABit is "0", an operation is performed to increase the upper limit value of the current transmission rate by one level.

In this case, increase the transfer rate probabilistically rather than absolutely.

That is, first generate a random number x (in the range of 0<x<1) (step 1002).

It is determined whether the generated random number x is smaller than the threshold α for changing the transmission rate (step 1003).

Here, the threshold α varies with the current transmission rate shown in FIG. 2 . For example, when trying to increase the transmission rate by one level from 9.6kbps to 19.2kbps, the threshold value α becomes a value generated by dividing "0x30" (hexadecimal notation) by 255 (that is, dividing "48" by 255) , ie, 48/255. In this example, at step 1003, it is determined whether the random number x is greater than or less than 48/255.

If it is determined in step 1003 that the random number x is smaller than the threshold α, the upper limit of the current transmission rate is increased by one level (step 1004). For example, if the current transfer rate is 9.6kbps, change it up one notch to 19.2kpbs. On the other hand, if it is determined that the random number x is equal to or greater than the threshold α, the upper limit value of the current transmission rate is maintained (step 1005). For example, if the current transfer rate is 9.6kbps, keep at 9.6kbps.

On the other hand, if it is determined in step 1001 that there is a base station having the RABit set to "1", an operation is performed to lower the upper limit value of the current transmission rate by one level. That is, first generate a random number x (in the range of 0<x<1) (step 1006), and compare the random number x with the threshold α (step 1007).

If it is determined that the random number x is smaller than the threshold α, then lower the upper limit of the current transmission rate by one level (step 1008).

For example, if the current transfer rate is 19.2kpbs, change it down by one notch, which is 9.6kpbs. On the other hand, if the random number x is equal to or greater than the threshold α, the upper limit value of the current transmission rate is maintained (step 1005).

For example, if the current transfer rate is 19.2kbps, keep at 19.2kbps.

Therefore, the radio communication terminal 200 can probabilistically and stepwise change the upper limit value of the transmission rate based on the RABit transmitted from the base station 100A every predetermined timing.

On the other hand, in addition to the processing using RABit in FIG. 3, the transmission rate of wireless communication terminal 200 may be forcibly changed in accordance with an instruction from a base station.

In the DO system, the base station 100A may transmit a control signal called "CurrentRateLimit" in addition to the RABit.

CurrentRateLimit is a control signal urgently transmitted to the wireless communication terminal 200 when the base station 100A is heavily congested and the throughput deteriorates significantly.

For example, the signal is urgently transmitted in the case where wireless communication terminals 200 are connected and concentrated to one radio station 100A, almost up to the upper limit of the number of terminals that the base station can connect to, and the base station may fail.

CurrentRateLimit includes information indicating any one of five transmission rate upper limit values of 9.6kbps, 19.2kbps, 38.4kbps, 76.8kbps and 153.6kbps, and the wireless communication terminal 200 receiving CurrentRateLimit sets the transmission rate to the indicated transmission rate. limit.

In this way, when receiving the CurrentRateLimit urgently transmitted from the base station 100A, the radio communication terminal 200 is forcibly set to the upper limit value of the transmission rate indicated by the CurrentRateLimit.

The mobile wireless communication terminal 200 of the present embodiment is capable of switching antennas so that during communication in the DO system, if the radio wave state between the wireless communication terminal and the base station deteriorates (for example, the pilot signal strength (RSSI value) decreases), Communication in the 1x system, which is another communication system, is then performed.

In this way, if the wireless communication terminal determines that satisfactory communication in the DO system cannot be performed due to deterioration of the radio wave state or the like, the wireless communication terminal can continue communication by switching from the DO system to the 1x system.

The communication switching from the DO system to the 1x system is called "hand down".

For the uplink communication in the 1x system, like the DO communication, the transmission rate is 9.6kbps at the beginning of the communication, but the upper limit of the transmission rate is always limited to 76.8kbps, and will not be gradually increased or decreased.

The handdown procedure of the wireless communication terminal 200 of the first embodiment when the RABit is transmitted from the base station 100A will be discussed below.

FIG. 4 is a flowchart showing a hand down process performed by the system control section 50 of the wireless communication terminal 200 of the first embodiment of the present invention.

When the wireless communication terminal 200 is performing uplink communication in the DO system, when the DO RF section 30 as the receiving section receives the RABit through the antenna 10, the system control section 50 determines whether there is a base station with the RABit set to "1", Even a base station (step 2001).

If it is determined that there is a base station having the RABit set to "1", that is, one base station, the system control section 50 as the determining section adds 1 to the variable "Y" (step 2002).

The variable Y is a value indicating the accumulated number of times RABits having the bit value "1" are successively received.

Next, it is determined whether the variable Y is equal to or greater than a predetermined threshold m (step 2003).

If it is determined that the variable Y is equal to or greater than the threshold m, that is, if it is determined that RABits having a bit value "1" have been successively received a predetermined number of times (threshold m) or more, then the system control section 50 as the control section sends a notification to the RF control section. The part 40 sends a command to make the RF control part 40 as the switching part perform hand down from the DO system to the 1x system (step 2004).

Thus, communication in the 1x system starts.

On the other hand, if it is determined in step 2001 that there is no base station with RABit set to "1", the variable Y is set to an initial value of 0 (step 2005), and communication in the DO system is continued without performing hand down (step 2006).

If it is determined in step 2003 that the variable Y is smaller than the predetermined threshold m, communication in the DO system is also continued without performing hand down (step 2006).

After step 2004 or step 2006, the flowchart loops to step 2001.

The threshold m compared with the variable Y which is the accumulated number of times RABit set to "1" is preset to a certain number of times, thereby assuming that it is difficult to increase the transmission rate any more due to the congestion of the DO system, if switching from the DO system to 1x If the communication is performed by the system, the communication can be performed at a higher speed.

For example, if the threshold m is set to "3" or "4", when the RABit set to "1" is only transmitted once (since the traffic is only temporarily concentrated in the base station 100A by chance, immediately after the RABit is set to "1") , when RABit is restored to "0"), the communication in the DO system can be continued without performing hand down.

FIG. 5 is a sequence diagram showing a hand down procedure performed by the system control section 50 of the wireless communication terminal 200 of the first embodiment of the present invention.

When the wireless communication terminal 200 is performing uplink communication in the DO system, the base station 100A transmits the RABit, and when the DO RF section 30 as the receiving section receives the RABit through the antenna 10, the system control section 50 determines whether there is an RABit set to "1". "The base station of RABit, even a base station. If it is determined that there are one or more base stations with the RABit set to "1", 1 is added to the variable "Y", and it is determined whether the variable Y is equal to or greater than the threshold value m.

If it is determined that variable Y is equal to or greater than threshold m, wireless communication terminal 200 transmits a "ConnectClose message" to base station 100A to disconnect communication in the DO system. Next, the radio communication terminal 200 establishes a 1x-TCH (1x system traffic channel) with the 1x system base station 100B.

Thereafter, when uplink communication using the 1x system is completed, it is preferable to disconnect the 1x-TCH and establish a DO-TCH (DO system traffic channel) with the base station 100A to restore a communicable state in the DO system.

As described above, when the wireless communication terminal 200 of the first embodiment of the present invention has successively received the RABit set to "1" a predetermined number of times (threshold value m) or more during communication in the DO system, execution from Hand down from DO system to 1x system. In this way, if the base station 100A is congested and communication cannot be performed at a satisfactory transmission rate in the DO system, the uplink communication in the DO system is abandoned and switched from the DO system to the 1x system where it is desirable to perform communication at a higher transmission rate .

Thus, the throughput of uplink communication can be enhanced.

Next, a second embodiment of the present invention will be discussed.

In the second embodiment, as in the first embodiment, the hand down procedure at the time of RABit transmission from the base station 100A will be discussed. The wireless communication system of the second embodiment is the same as that in FIG. 1 .

FIG. 6 is a flowchart showing a handdown process performed by the system control section 50 of the wireless communication terminal 200 of the second embodiment of the present invention. Steps 2001 to 2006 are similar to those in the first embodiment shown in FIG. 4 , thus denoted by the same step numbers in FIG. 6 and will not be discussed again.

If it is determined in step 2003 that the RABit having the bit value "1" has been successively received at the predetermined threshold m or more times, the system control section 50 as the comparison section compares the upper limit value of the current transmission rate with the predetermined threshold n, to determine whether the upper limit is lower than the threshold n (step 2007).

If it is determined that the upper limit value of the current transmission rate is lower than the threshold value n as a result of the comparison, the process proceeds to step 2004, and the system control section 50 as the control section sends a command to the RF control section 40 to make the RF control section 40 as the switching section execute Hand down from the DO system to the 1x system to start communication in the 1x system (step 2004).

On the other hand, if it is determined in step 2007 that the upper limit of the current transmission rate is equal to or greater than the threshold n, communication in the DO system is continued without hand down (step 2006).

The threshold n is preset as a transmission rate at which it is assumed that communication can be performed at high speed when switching from the DO system to the 1x system. For example, the upper limit value (76.8kpbs) of the uplink transmission rate in the 1x system may be used as the value of n.

As described above, only when the upper limit value of the actual transmission rate becomes lower than a predetermined threshold value as a result of successively receiving RABit set to "1" a predetermined number of times (threshold value m) or more during communication in the DO system When n, the wireless communication terminal 200 in the second embodiment of the present invention executes hand down.

In this way, the following advantages are provided: if RABit is set to "1", a random number x is generated, and if the comparison result between the random number x and the threshold α is that the random number x is equal to or greater than the threshold α, then as in the first embodiment As mentioned above, keep the upper limit of the transmission rate. Therefore, even if the RABit indicating "1" is received a predetermined number of times Y or more, if the acquired random number x exceeds the threshold value α, the transmission rate upper limit value is not lowered. Therefore, if RABit indicating "1" is received, communication can be performed at a higher speed if communication is continued in the DO system without lowering the upper limit value of the actual transmission rate.

In the second embodiment, the upper limit value of the actual transmission rate is compared with the predetermined threshold value n, only when the actual transmission rate decreases, the hand down is executed, and when the upper limit value of the DO system transmission rate is high enough, the Communication continues in the DO system without performing hand down to the 1x system. Thus, the throughput of uplink communication can be enhanced.

Next, a third embodiment of the present invention will be discussed.

In the third embodiment, the handdown process when RABit is transmitted from the base station 100A shown in the first embodiment will be discussed. The wireless communication system of the third embodiment is the same as that in FIG. 1 .

FIG. 7 is a flowchart showing a hand down procedure performed by the system control section 50 of the wireless communication terminal 200 of the third embodiment of the present invention. Steps 2001 to 2007 are similar to those in the first and second embodiments shown in Figs. 4 and 6, and thus are denoted by the same step numbers in Fig. 7 and will not be discussed again.

For example, if it is determined in step 2007 that the upper limit value of the current transmission rate is lower than the threshold n, the system control section 50 as the derivation section derives the data amount of the target data for uplink communication by referring to the buffer in the system storage section 60 .

It is determined whether the amount of derived data is equal to or greater than a predetermined threshold β (step 2008).

If the determined result is that the amount of data derived is equal to or greater than the predetermined threshold β, the system control section 50 as the control section sends a command to the RF control section 40 so that the RF control section 40 as the switching section performs handover from the DO system to the 1x system down to start communication in the 1x system (step 2004).

On the other hand, if it is determined in step 2008 that the derived data amount is smaller than the predetermined threshold β, the communication in the DO system is continued without performing hand down (step 2006).

The predetermined threshold β is preset as the amount of data in which, assuming that due to congestion of the DO system, communication can be performed efficiently if hand down from the DO system to the 1x system is performed.

In this case, the determination may be made by comparing the total amount of data to be transferred with a threshold β, or comparing the amount of untransferred data obtained by subtracting the amount of transferred data from the total amount of data to be transferred with the threshold β to make sure.

As described above, when the upper limit value of the actual transmission rate becomes lower than the predetermined threshold n as a result of successively receiving RABit set to "1" a predetermined number of times (threshold m) or more during communication in the DO system When low, the wireless communication terminal 200 of the third embodiment of the present invention executes hand down from the DO system to the 1x system only when it is determined that the amount of data equal to or greater than the threshold β is to be transmitted.

In this way, the following advantages are provided:

The hand down process from a DO system to a 1x system requires a certain amount of processing time. If the upper limit of the transmission rate of the DO system is somewhat low, in order to transmit a small amount of data that completes its transmission in a short time, if the hand down from the DO system to the 1x system is performed, the time for the hand down process is required; until all the data The total time for the transfer to complete may become longer than it would have taken if no hand down from the DO system to the 1x system was performed.

In this embodiment, if the amount of data is so small that hand down should be skipped, communication in the DO system is continued without performing hand down to the 1x system. Thus, the throughput of uplink communication can be enhanced.

Next, a fourth embodiment of the present invention will be discussed.

In the fourth embodiment, the hand down process when the CurrentRateLimit is transmitted from the base station 100A will be discussed. The wireless communication system of the fourth embodiment is the same as that in FIG. 1 .

FIG. 8 is a flowchart showing a handdown process performed by the system control section 50 of the wireless communication terminal 200 of the fourth embodiment of the present invention.

When the wireless communication terminal 200 is performing uplink communication in the DO system, when the DO RF part 30 as the receiving part receives the CurrentRateLimit through the antenna 10, the system control part 50 as the comparing part will set the transmission rate upper limit value indicated by the CurrentRateLimit Compared with a predetermined threshold n (step 3001).

If it is determined that the transmission rate upper limit indicated by CurrentRateLimit is lower than the predetermined threshold n, then the system control part 50 as the control part sends an order to the RF control part 40, so that the RF control part 40 as the switching part executes the slave DO system To the hand down of the 1x system to start communication in the 1x system (step 3002).

On the other hand, if it is determined in step 3002 that the comparison result is CurrentRateLimit and the transmission rate upper limit value indicated is higher than the predetermined threshold n, continue the communication in the DO system without performing hand down (step 3003).

A threshold value n compared with the transmission rate upper limit value indicated by CurrentRateLimit is preset as the transmission rate, thereby assuming that communication can be performed at a higher speed if communication is performed by switching from the DO system to the 1x system.

For example, the upper limit of the uplink transmission rate (76.8 kpbs) in the 1x system may be used as the value of n.

FIG. 9 is a sequence diagram showing a hand down procedure performed by the system control section 50 of the wireless communication terminal 200 of the fourth embodiment of the present invention.

When the wireless communication terminal 200 is performing uplink communication in the DO system, the base station 100A transmits the CurrentRateLimit, and when the DO RF part 30 as the receiving part receives the CurrentRateLimit through the antenna 10, the system control part 50 will increase the transmission rate indicated by the CurrentRateLimit The limit value is compared with a predetermined threshold n. If the indicated transmission rate upper limit value is lower than the predetermined threshold n when the comparison result is determined to be CurrentRateLimit, wireless communication terminal 200 transmits a "ConnectionClose message" to base station 100A to disconnect communication in the DO system. Next, the radio communication terminal 200 establishes a 1x-TCH (1x system traffic channel) with the 1x system base station 100B.

Thereafter, when uplink communication using the 1x system is completed, it is preferable to disconnect the 1x-TCH and establish a DO-TCH (DO system traffic channel) with the base station 100A to restore a communicable state in the DO system.

As described above, when the wireless communication terminal 200 of the fourth embodiment of the present invention receives the CurrentRateLimit indicating that the transmission rate is lower than the predetermined transmission rate (threshold n) during the communication in the DO system, the transfer from the DO system to the 1x system is performed. hand down.

Thus, if the base station 100A is so congested that communication cannot be performed at a satisfactory transmission rate, the DO system is abandoned and switched to the 1x system where communication at a higher transmission rate can be desired.

Thus, the throughput of uplink communication can be enhanced.

Next, a fifth embodiment of the present invention will be discussed.

In the fifth embodiment, the hand down process when the CurrentRateLimit is transmitted from the base station 100A shown in the fourth embodiment will be discussed. The wireless communication system of the fifth embodiment is the same as that in FIG. 1 .

FIG. 10 is a flowchart showing a handdown process performed by the system control section 50 of the wireless communication terminal 200 of the fifth embodiment of the present invention. Steps 3001 to 3003 are similar to the steps of the fourth embodiment shown in FIG. 8 , so they are denoted by the same step numbers in FIG. 10 , and will not be discussed again.

For example, if it is determined in step 3001 that the transmission rate upper limit indicated by CurrentRateLimit is lower than the predetermined threshold n, the system control section 50 as the derivation section derives the target data for uplink communication by referring to the buffer in the system storage section 60 amount of data.

It is determined whether the amount of derived data is equal to or greater than a predetermined threshold β (step 3004). If the determined result is that the amount of data derived is equal to or greater than the predetermined threshold β, the system control section 50 as the control section sends a command to the RF control section 40 so that the RF control section 40 as the switching section performs handover from the DO system to the 1x system down to start communication in the 1x system (step 3002).

On the other hand, if it is determined in step 3004 that the derived data amount is smaller than the predetermined threshold β, the communication in the DO system is continued without performing hand down (step 3003).

A predetermined threshold β is preset as the amount of data, where, assuming that due to congestion of the DO system, communication can be efficiently performed if hand down from the DO system to the 1x system is performed.

In this case, the determination may be made by comparing the total amount of data to be transferred with a threshold β, or comparing the amount of untransferred data obtained by subtracting the amount of transferred data from the total amount of data to be transferred with the threshold β to make sure.

As described above, only when it is determined that the amount of data equal to or greater than the predetermined threshold β is to be transmitted when the CurrentRateLimit indicating that the transmission rate is lower than the predetermined transmission rate (threshold n) is received during communication in the DO system, the fifth embodiment of the present invention The wireless communication terminal 200 of the example executes hand down from the DO system to the 1x system.

In this way, the following advantages are provided:

The hand down process from a DO system to a 1x system requires a certain amount of processing time. If the upper limit of the transmission rate of the DO system is somewhat low, in order to transmit a small amount of data that completes its transmission in a short time, if the hand down from the DO system to the 1x system is performed, the time for the hand down process is required; until all the data The total time for the transfer to complete may become longer than it would have taken if no hand down from the DO system to the 1x system was performed.

In this embodiment, if the amount of data is so small that hand down should be skipped, communication in the DO system is continued without performing hand down to the 1x system. Thus, the throughput of uplink communication can be enhanced.

The case where CurrentRateLimit is received during communication in the DO system is described in the fourth and fifth embodiments, but the present invention can also be applied to the case where CurrentRateLimit is received when communication in the DO system is started.

In any one of the above-mentioned first to fifth embodiments, if the uplink transmission rate in the DO system is too low to provide satisfactory throughput, switch from the DO system to the 1x system which may wish to perform faster communication, to perform communication, so that the throughput of the wireless communication terminal 200 can be enhanced.

The schemes of the first to fifth embodiments can be combined.

That is, when receiving RABit, the wireless communication terminal 200 can execute the processing of the first embodiment in FIG. 4; when receiving the CurrentRateLimit, the wireless communication terminal 200 can execute the processing of the fourth embodiment in FIG. 8.

In the embodiment of the present invention, the radio wave state with the base station is determined using the pilot signal strength (RSSI value), but the carrier-to-interference ratio (C/I value) of the pilot signal may be used instead of the pilot signal strength (RSSI value). ).

A hybrid system of the CDMA2000 1x system and the CDMA2000 1xEVDO system is described in the embodiments of the present invention, but the present invention is not limited thereto. If communication can be performed in two or more communication systems, and the communication systems can be switched so that data communication is performed in one communication system and switched from that communication system to another communication system to perform data communication, any type of communication system.

A sixth embodiment of the present invention will be discussed below with reference to the accompanying drawings:

FIG. 11 is a block diagram showing the configuration of wireless communication terminal 200 of the sixth embodiment of the present invention.

The wireless communication terminal (mobile phone terminal) 200 of the present embodiment is capable of switching between the CDMA2000 1x communication system (hereinafter referred to as "1x system") and the 1xEVDO communication system (hereinafter referred to as "DO system") to use A wireless communication terminal that shares the antenna 10 to perform communication with the DO system base station 100 (100a, 100b, 100c) or the 1x system base station 101.

Base stations 100 a , 100 b , and 100 c perform DO system communication with wireless communication terminal 200 , and base station 101 performs 1× system communication with wireless communication terminal 200 .

Hereinafter, a base station to which wireless communication terminal 200 is connected to perform communication is referred to as a "connected base station", and one or more base stations adjacent to the connected base station as handover destination candidates are referred to as "peripheral base stations".

The antenna 10 converts radio frequency signals from the 1xRF section 20 or the DO RF section 30 into radio waves, transmits radio waves to the base stations 100 and 101, receives radio waves from the base stations 100 and 101, and transmits the radio waves to the 1xRF section 20 as radio frequency signals or DO RF Part 30.

The 1xRF part 20 converts data or voice signals transmitted in the 1x system into radio frequency signals and transmits the radio frequency signals to the antenna 10 . The 1xRF section 20 also converts the radio frequency signal transmitted from the antenna 10 into a data signal or a voice signal.

The DO RF section 30 converts data transmitted in the DO system into a radio frequency signal, and transmits the radio frequency signal to the antenna 10.

The DO RF section 30 also converts radio frequency signals transmitted from the antenna 10 into data signals.

The DO RF section 30 functions as a receiving section and a transmitting section.

The RF control section 40 is a control section for controlling communication of two systems, the DO system and the 1x system.

The RF control section 40 measures the intensity (RSSI etc.) of radio waves received at the antenna 10 from the base station.

The system control section 50 is a control section for performing centralized control of various sections of the wireless communication terminal 200 .

The system control part 50 controls the RF control part 40 to control switching between the DO system and the 1x system. The system control section 50 functions as a generating section and a determining section.

The system storage section 60 is realized by a memory such as a RAM, and stores application programs, temporary data, and the like.

The operation of the wireless communication terminal 200 of the sixth embodiment of the present invention is as follows:

First, changes in the transmission rate upper limit value of the wireless communication terminal of the present embodiment in DO system data communication will be discussed below with reference to FIGS. 2 and 3 .

First, in the uplink communication of the DO system, the upper limit of the transmission rate is classified into five levels: 9.6kbps, 19.2kbps, 38.4kbps, 76.8kbps and 153.6kbps.

When the wireless communication terminal 200 starts the uplink communication with the base station 100a, the wireless communication terminal first starts communication at the lowest transmission rate (9.6kbps), and then the wireless communication terminal 200 starts communication according to the degree of congestion of the base station 100a connected to the base station and the surrounding base stations as the base station 100a. The upper limit value of the transmission rate is changed according to the degree of congestion of the handover destination candidate base stations 100b and 100c.

Specifically, the connecting base station 100a has information indicating the base stations 100b and 100c as handover destination candidates as "Activeset". Each of the connected base station 100a and the surrounding base stations 100b and 100c registered in Activeset transmits RABit (Reverse Active Bit), which is instruction information for increasing or decreasing the upper limit value of the transmission rate according to the degree of congestion of each base station . The wireless communication terminal 200 receives the RABit, and adjusts the transmission rate.

"RABit" is a value that varies with the congestion state of the base station.

The congestion of the base station means a case where a large number of wireless communication terminals are connected to the base station in a concentrated manner, a case where congestion occurs in a communication line, and the like. If there is no congested base station, that is, if the transmission rate can be increased, RABit is set to "0".

RABit is set to "1" if there are one or more congested base stations, ie if increasing the transmission rate is not preferred. RABit is used as instruction information (change or lower the upper limit value) indicating the upper limit value of the transmission rate of the wireless communication terminal 200 .

FIG. 3 is a flowchart of transmission rate change performed by the system control section 50 of the wireless communication terminal 200. As shown in FIG.

When the wireless communication terminal 200 starts uplink communication in the DO system, the wireless communication terminal first starts communication at the lowest transmission rate (9.6 kbps).

Next, when the antenna 10 receives the RABit from the base station 100a registered in Activeset and the surrounding base stations 100b and 100c, it is determined whether the RABit is set to "1" (step 1001).

If it is determined that the RABits are all "0", an operation is performed to increase the upper limit value of the current transmission rate by one level.

In this case, increase the transfer rate probabilistically rather than absolutely.

That is to say, first generate a random number x (in the range of 0<x<1) (step 1002).

It is determined whether the generated random number x is smaller than the threshold α for changing the transmission rate (step 1003). Here, the threshold α varies with the current transmission rate shown in FIG. 2 . For example, when trying to increase the transmission rate by one level from 9.6kbps to 19.2kbps, the threshold value α becomes a value generated by dividing "0x30" (hexadecimal notation) by 255 (that is, dividing "48" by 255) , ie, 48/255.

In this example, at step 1003, it is determined whether the random number x is greater than or less than 48/255.

If it is determined in step 1003 that the random number x is smaller than the threshold α, the upper limit of the current transmission rate is increased by one level (step 1004).

For example, if the current transfer rate is 9.6kbps, change it up one notch to 19.2kpbs. On the other hand, if it is determined that the random number x is equal to or greater than the threshold α, the upper limit value of the current transmission rate is maintained (step 1005). For example, if the current transfer rate is 9.6kbps, keep at 9.6kbps.

On the other hand, if it is determined in step 1001 that there is a base station having RABit set to "1", ie one base station, an operation is performed to lower the upper limit value of the current transmission rate by one level.

That is to say, first generate a random number x (in the range of 0<x<1) (step 1006), and compare the random number x with the threshold α (step 1007).

If it is determined that the random number x is smaller than the threshold α, then lower the upper limit of the current transmission rate by one level (step 1008).

For example, if the current transfer rate is 19.2kpbs, change it down by one notch, which is 9.6kpbs. On the other hand, if the random number x is equal to or greater than the threshold α, the upper limit value of the current transmission rate is maintained (step 1005).

For example, if the current transfer rate is 19.2kbps, keep at 19.2kbps.

Therefore, wireless communication terminal 200 can probabilistically and stepwise change the upper limit value of the transmission rate based on RABit transmitted from each of connected base station 100a and peripheral base stations 100b and 100c registered in Activeset every predetermined timing.

On the other hand, if one of the peripheral base stations registered in Activeset is congested, wireless communication terminal 200 performs an operation to lower the upper limit value of the transmission rate. Therefore, for example, if handover is performed from the base station 100a performing communication at high speed to the congested base station 100b performing communication only at low speed, communication errors such as packet loss due to a rapid decrease in the transmission rate can be prevented from occurring.

Based on the communication quality between the wireless communication terminal 200 and the base station 100, the Activeset of the base station 100a is updated.

Fig. 13 is a sequence diagram showing the updating process of the Activeset in this embodiment; Fig. 13(a) shows that the base station is added to the Activeset, and Fig. 13(b) shows that the base station is removed from the Activeset.

In FIG. 13( a ), the radio communication terminal 200 communicates with the base station 100 a as a connection base station.

At this time, it is assumed that the neighboring base stations 100b are not registered in Activeset. Here, wireless communication terminal 200 measures the signal strength (RSSI value) of the pilot signal of peripheral base station 100b, and transmits a "RouteUpdate message" including the measured value to connecting base station 100a.

When receiving the RouteUpdate message, if the measured value is equal to or greater than a predetermined threshold ζ (ζ is a threshold for registering base stations in the Activeset), the connected base station 100a registers the surrounding base stations 100b in the Activeset, and transmits to the wireless communication terminal 200 "TCA (Traffic Channel Assignment) message" to indicate the effect of registering the surrounding base stations 100b in the Activeset.

The wireless communication terminal 200 obtains the information of the surrounding base stations 100b added to Activeset according to the TCA message.

On the other hand, in FIG. 13(b), wireless communication terminal 200 communicates with base station 100b as a connection base station.

At this time, it is assumed that the surrounding base stations 100a are registered in Activeset.

Here, the wireless communication terminal 200 measures the signal strength of the pilot signal of the peripheral base station 100a, and transmits a RouteUpdate message including the measured value to the connecting base station 100b.

When receiving the RouteUpdate message, if the measured value is less than a predetermined threshold ζ (ζ is a threshold for registering a base station in the Activeset), the connected base station 100b removes the peripheral base station 100a from the Activeset, and transmits a TCA message to the wireless communication terminal 200, To indicate the effect of removing the surrounding base station 100a from the Activeset.

The wireless communication terminal 200 obtains the information of the neighboring base stations 100a removed from the Activeset according to the TCA message.

As described above, base stations are registered in Activeset or removed therefrom, whereby peripheral base stations 100 having good communication quality (signal strength of pilot signal equal to or greater than threshold ζ) between wireless communication terminal 200 and base station 100 are gradually set. Candidates for handover destinations so that communication can always be performed with good communication quality.

On the other hand, peripheral base stations 100 having poor communication quality (signal strength of pilot signal smaller than threshold ζ) between wireless communication terminal 200 and base station 100 are removed from the candidates of the handover destination. Therefore, it is possible to prevent unnecessary hand down to the base station, which has poor communication quality and may be disconnected immediately after connection.

If there is a congested base station among the base stations registered in the Activeset, even if there is one base station, and the base station indicates RABit="1", even if the connected base station and other surrounding base stations are not congested and indicate RABit="0", it is not according to Fig. 3 processing to increase the upper limit of the transmission rate.

Next, in order to perform DO system communication, the wireless communication terminal 200 of this embodiment performs the following processing:

FIG. 14 is a flow chart of uplink data transmission in the DO system performed by the wireless communication terminal 200 .

Assume that the connecting base station 100a registers the neighboring base stations 100b and 100c in Activeset.

The radio communication terminal 200 starts uplink data communication with the base station 100a as the connection base station.

During uplink data communication, DO RF section 30 (receiving section) of wireless communication terminal 200 receives RABit transmitted at every predetermined timing by each of peripheral base stations 100b and 100c registered in Activeset (step 2001).

When receiving the RABit, the system control section 50 determines whether a plurality of surrounding base stations are registered in the Activeset (step 2002). When only one peripheral base station is registered in the Activeset, if the base station is removed from the Activeset, the base station performing the handover disappears, so that the process proceeds to step 2005 to perform data transmission.

If it is determined in step 2002 that a plurality of peripheral base stations are registered in the Activeset, the system control section 50 (determining section) determines whether the peripheral base stations registered in the Activeset include a peripheral indicating RABit="1" (that is, congested and difficult to increase the transmission rate). A base station, ie a base station (step 2003).

If the determination result is that the surrounding base stations indicating RABit="1" are not registered in Activeset, ie, if all surrounding base stations indicate RABit="0" and the transmission rate can be increased, the procedure proceeds to step 2005, and data transmission is performed.

If it is determined in step 2003 that there is a peripheral base station indicating RABit="1" in the Activeset, even one base station, for example, if the peripheral base station 100b among the peripheral base stations is congested and indicates RABit="1", the system control section 50 (generating section) A RouteUpdate message for removing the peripheral base station 100b from the Activeset is generated and transmitted from the DO RF section 30 to the connecting base station 100a through the antenna section 10 (step 2004).

The RouteUpdate message for removing the surrounding base station 100b from the Activeset includes a value indicating "false pilot signal strength", indicating that the pilot signal strength of the surrounding base station 100b is less than the threshold ζ, and the signal strength of the actual pilot signal of the surrounding base station 100b is not transmitted.

As previously described with reference to FIG. 13, the threshold ζ is a signal strength threshold used by the base station 100a to register another base station in the Activeset.

When receiving the RouteUpdate message including "wrong pilot signal strength", the base station 100a determines that the pilot signal strength is less than the threshold ζ, and performs the process of removing the surrounding base station 100b indicating the pilot signal strength from the Activeset. The result is transmitted to wireless communication terminal 200 .

Wireless communication terminal 200 performs data transmission (step 2005).

During data transmission, a transmission rate changing process is performed at a predetermined timing to probabilistically change the upper limit of the transmission rate as previously described with reference to FIG. 13 . In this case, since the surrounding base stations indicating RABit="1" are removed from the Activeset in step 2004, the upper limit of the transmission rate is increased.

This process is repeated until the data transfer is complete (step 2006).

If it is determined that the data transmission is complete, a process of re-registering the base station 100b removed from the Activeset for data transmission in step 2004 in the Activeset is performed (step 2007).

That is, the RouteUpdate message generated and transmitted in step 2004 including the "correct" pilot signal strength between the peripheral base station 100b and the wireless communication terminal 200 instead of the "wrong" pilot signal strength is transmitted. If the "correct" pilot signal strength is equal to or greater than the threshold ζ, the connecting base station 100a re-registers the surrounding base stations 100b in the Activeset.

When the processing in FIG. 14 is performed, in data communication, peripheral base stations that are congested and therefore not allowed to increase the transmission rate (indicating RABit="1") are removed from the Activeset of connected base stations to perform data communication, thereby performing data communication according to FIG. 13 The processing in increases the upper limit value of uplink data transmission. In this way, the throughput of uplink data transmission can be enhanced.

FIG. 15 is a sequence diagram of uplink data transmission time in the DO system executed by the wireless communication terminal 200 .

The wireless communication terminal 200 starts communication with the connection base station 100a.

If the base station 100b among the peripheral base stations registered in the Activeset is congested, and therefore enters a state where the transmission rate cannot be increased, and indicates RABit="1", a RouteUpdate message including "wrong pilot signal strength" is generated and transmitted to The base station 100a is connected to remove the surrounding base stations 100b from the Activeset.

When receiving the RouteUpdate message including "wrong pilot signal strength", the base station 100a determines that the pilot signal strength is less than the threshold ζ, and performs the process of removing the surrounding base station 100b indicating the pilot signal strength from the Activeset. A TCA message is sent to the wireless communication terminal 200 to notify that the base station 100b is removed from the Activeset.

Wireless communication terminal 200 performs data transmission in this state, that is, in a state in which base stations that are not allowed to increase the transmission rate due to congestion are removed.

If it is determined that the data transmission is complete, a RouteUpdate message including "correct" pilot signal strengths rather than "wrong" pilot signal strengths between the surrounding base stations 100b and the wireless communication terminal 200 is transmitted to reset the base station 100b removed from the Activeset Registered in Activeset.

If the "correct" pilot signal strength is equal to or greater than the threshold ζ, the connected base station 100a registers the neighboring base stations 100b in Activeset. A TCA message is sent to wireless communication terminal 200 to notify that base station 100b has been registered in Activeset.

In the sixth embodiment of the present invention described above, in the data communication, among the base stations registered in the Activeset, peripheral base stations that are not allowed to increase the transmission rate (indicating RABit="1") due to congestion are removed from the Activeset to perform data communication. Transmission, therefore, probabilistically changes the upper limit value of the uplink data transmission rate, thereby increasing the transmission rate.

In this way, the throughput of uplink data communication can be enhanced.

A seventh embodiment of the present invention will be discussed below.

In the seventh embodiment, like the sixth embodiment, base stations are removed from Activeset at data communication time.

The wireless communication system of the seventh embodiment is the same as that of the sixth embodiment of FIG. 11 .

FIG. 16 is a flowchart of uplink data transmission in the DO system performed by the wireless communication terminal 200 of the seventh embodiment.

Steps 2001 to 2007 are similar to the sixth embodiment in FIG. 14 , thus denoted by the same step numbers in FIG. 16 , and will not be discussed again.

In step 2001, during uplink data communication, the DO RF section 30 (receiving section) of the wireless communication terminal 200 receives the RABit transmitted at every predetermined timing by each of the peripheral base stations 100b and 100c registered in the Activeset (step 2001 ).

Next, for example, the system control section 50 (derivation section) derives the data amount of target data for uplink communication by referring to the buffer in the system storage section 60, and determines whether the derived data amount is equal to or greater than the threshold value β (step 2008).

If the determined result is that the amount of derived data is smaller than the threshold β, the process proceeds to step 2005 to continue data transmission.

On the other hand, if the determined result at step 2008 is that the amount of derived data is equal to or greater than the threshold value β, steps 2002 to 2007 are performed.

That is, it is determined whether a plurality of surrounding base stations are registered in Activeset (step 2002). If it is determined that there are a plurality of peripheral base stations registered in the Activeset, the system control section 50 (determining section) determines whether the peripheral base stations registered in the Activeset include a peripheral base station indicating RABit="1", that is, a peripheral base station that is congested and difficult to increase the transmission rate, even if There is only one base station (step 2003).

If it is determined that peripheral base stations indicating RABit="1" are registered in the Activeset, even if there is only one base station, the system control part 50 (generating part) then generates a RouteUpdate message including "wrong pilot signal strength" to remove the peripheral base stations from the Activeset 100b, and transmit the message from the DO RF section 30 to the connecting base station 100a through the antenna section 10 (step 2004).

As a result, the neighboring base stations 100b are removed from Activeset. The wireless communication terminal 200 performs data transmission (step 2005), and when the data transmission is completed, the wireless communication terminal 200 sends a RouteUpdate message including the "correct" pilot signal strength between the surrounding base stations 100b and the wireless communication terminal 200 (step 2007).

When the processing in FIG. 16 is executed, if the amount of transmitted data is equal to or greater than the predetermined threshold β, the surrounding base stations that are congested and therefore not allowed to increase the transmission rate (indicating RABit="1") are removed from the Activeset of the connected base station to perform Data communication, thereby increasing the upper limit value of the uplink data transmission rate according to the process in FIG. 3 . In this way, the throughput of uplink data transmission can be enhanced.

FIG. 17 is a sequence diagram of uplink data transmission in the DO system performed by the wireless communication terminal 200 .

The wireless communication terminal 200 starts communication with the connection base station 100a.

If base station 100b among peripheral base stations registered in Activeset is congested, and thus enters a state where the transmission rate cannot be increased, and indicates RABit="1", wireless communication terminal 200 determines whether the transmission data amount is equal to or greater than threshold β.

In order to transmit a data amount equal to or greater than the threshold β, a RouteUpdate message including "Wrong Pilot Signal Strength" is generated and transmitted to the connected base station 100a to remove peripheral base stations indicating RABit="1" from the Activeset.

When receiving the RouteUpdate message including "wrong pilot signal strength", the base station 100a determines that the pilot signal strength is less than the threshold ζ, and performs the process of removing the surrounding base station 100b indicating the pilot signal strength from the Activeset. A TCA message is sent to the wireless communication terminal 200 to notify that the base station 100b has been removed from the Activeset.

Radio communication terminal 200 performs data transmission in a state in which base stations that are not allowed to increase the transmission rate due to congestion (indication RABit="1") are removed.

If it is determined that the data transmission is complete, a RouteUpdate message including "correct" pilot signal strengths rather than "wrong" pilot signal strengths between the surrounding base stations 100b and the wireless communication terminal 200 is transmitted to reset the base station 100b removed from the Activeset Registered in Activeset.

If the "correct" pilot signal strength is equal to or greater than the threshold ζ, the connecting base station 100a re-registers the surrounding base stations 100b in the Activeset.

A TCA message is sent to the wireless communication terminal 200 to notify that the base station 100b has been registered in Activeset.

In the seventh embodiment of the present invention described above, in data communication, only when the amount of data equal to or greater than the threshold value β is to be transmitted, base stations registered in the Activeset that do not allow an increase in the transmission rate due to congestion ( Indicates the surrounding base stations of RABit="1").

Therefore, the following advantages are provided:

In order to perform a small amount of data transfer requiring a short time, if it takes time for the Activeset change process (steps 2002 to 2007 of FIG. 16) and increases the transfer rate, its effect is small. Therefore, the Activeset change procedure should only be performed when large amounts of data are being transferred.

In this way, the throughput of uplink data communication can be enhanced.

In the embodiment of the present invention, the pilot signal strength (RSSI value) is used to determine the radio wave state of the base station 100, but the ratio of the carrier wave to the interference wave (C/I value) of the pilot signal may be used instead of the pilot signal. Signal strength (RSSI value).

In the embodiments of the present invention, a hybrid system of the CDMA2000 1x system and the CDMA2000 1xEVDO system performing wireless communication using a shared antenna is described, but the present invention is not limited thereto. Wireless communication can be performed using separate antennas.

In the embodiments of the present invention, a hybrid system of the CDMA2000 1x system and the CDMA2000 1xEVDO system is described, but the present invention is not limited thereto. If the communication system changes the transmission rate according to the congestion state of the base station, any of these communication systems may be employed.

Industrial Applicability

According to the configurations (1) to (30) of the present invention, the throughput of a wireless communication terminal capable of performing communication in a plurality of communication systems can be enhanced, and therefore, industrial applicability is very strong.

The present invention is not limited to the above-described embodiments.

Claims (30)

1. A wireless communication terminal, comprising: a switching section for switching between a first communication system whose transmission rate upper limit value is changed and a second communication system; a receiving section configured to receive information indicating a transmission rate upper limit value in the first communication system from a base station; a comparing section for comparing the upper limit value received by the receiving section with a predetermined reference value at the start of communication or during communication with a base station in the first communication system; and A control section for performing switching control of the switching section to perform communication in the second communication system when the result of the comparison by the comparison section is that the upper limit value is lower than a reference value. 2. A wireless communication terminal, comprising: a switching section for switching between a first communication system whose transmission rate upper limit value is changed and a second communication system; a receiving section for receiving, at each predetermined timing, instruction information from a base station indicating to change a transmission rate upper limit value in said first communication system; a determining section for determining whether instruction information for instructing lowering of the transmission rate upper limit value is successively received a predetermined number of times or more during communication with a base station in the first communication system; and a control section for performing switching control of the switching section when the result of the determination by the determining section is that instruction information for instructing lowering of the upper limit value of the transmission rate has been successively received a predetermined number of times or more , so as to communicate in the second communication system. 3. The wireless communication terminal according to claim 2 , wherein said control section is determined by said determination section only when a transmission rate upper limit value in said first communication system is lower than a predetermined reference value. The switching control of the switching section is performed when instruction information for instructing lowering of the transmission rate upper limit value is successively received a predetermined number of times or more. 4. The wireless communication terminal according to claim 1 or 3, wherein the reference value is a value at which a transmission rate is expected to increase when communication is performed in said second communication system instead of said first communication system. 5. The wireless communication terminal according to claim 1, comprising: a deriving part for deriving a remaining amount of data to be transmitted in said first communication system, wherein only when the amount of remaining data derived by the deriving portion is greater than a predetermined amount, the control portion executes switching to the second communication system when the result of the comparison by the comparing portion is an upper limit value lower than a reference value switch control. 6. The wireless communication terminal according to claim 2, comprising: a deriving part for deriving a remaining amount of data to be transmitted in said first communication system, Wherein only when the remaining data amount derived by the deriving portion is larger than a predetermined amount, the control portion determines that the result of the determination by the determining portion is successively received the number of times equal to or more than the predetermined number of times for instructing to reduce the transmission When the instruction information of the upper limit value of the rate is received, the switching control of switching to the second communication system is performed. 7. A program for use in a wireless communication terminal in which communication is performed by switching between a first communication system in which a transmission rate upper limit value is changed and a second communication system, the program comprising : The first process is used to receive information indicating the upper limit value of the transmission rate in the first communication system from the base station; a second process for comparing the upper limit value received by the receiving section with a predetermined reference value at the start of communication or during communication with a base station in the first communication system; and A third process for switching from the first communication system to the second communication system when the comparison result obtained by the second process is that the upper limit value is lower than a reference value. 8. A program for use in a wireless communication terminal in which communication is performed by switching between a first communication system in which a transmission rate upper limit value is changed and a second communication system, the program comprising : A first process for receiving, at each predetermined timing, instruction information from a base station indicating to change an upper limit value of a transmission rate in the first communication system; A second process for determining whether, during communication with a base station in the first communication system, instruction information for instructing lowering of the upper limit value of the transmission rate is successively received a predetermined number of times or more; and A third process of switching from the first communication system to The second communication system. 9. The program according to claim 8 , wherein in said third process, only when the transmission rate upper limit value in said first communication system is lower than a predetermined reference value, in said second process obtained A determination result is that switching from the first communication system to the second communication system is performed when instruction information instructing to lower the transmission rate upper limit value is successively received a predetermined number of times or more. 10. The program according to claim 7 or 9, wherein the reference value is a value at which a transmission rate is expected to increase when communication is performed in said second communication system instead of said first communication system. 11. The program of claim 7 comprising: a fourth procedure for deriving a remaining amount of data to be transmitted in said first communication system, Wherein in the third process, only when the remaining data amount derived by the fourth process is greater than a predetermined amount, and only when the comparison result by the second process is that the upper limit value is lower than the reference value, the execution from the fourth process is carried out. Handover from a communication system to said second communication system. 12. The program of claim 8, comprising: a fourth procedure for deriving a remaining amount of data to be transmitted in said first communication system, Wherein only when the remaining data amount derived by the fourth process is greater than a predetermined amount, the determination result obtained by the second process is that instructions for lowering the upper limit of the transmission rate are successively received a number of times equal to or more than a predetermined number of times When there is instruction information of value, switching from the first communication system to the second communication system is performed. 13. A communication method for performing communication in a wireless communication terminal by switching between a first communication system and a second communication system in which a transmission rate upper limit value is changed, the communication method comprising: receiving information indicating a transmission rate upper limit value in the first communication system from a base station; comparing the upper limit value received from the base station with a predetermined reference value at the start of communication or during communication with the base station in the first communication system; and When the comparison result is that the upper limit value is lower than the reference value, switching from the first communication system to the second communication system. 14. A communication method for performing communication in a wireless communication terminal by switching between a first communication system in which a transmission rate upper limit value is changed and a second communication system, the communication method comprising: receiving instruction information from the base station at each predetermined timing indicating to change the transmission rate upper limit value in the first communication system; determining whether instruction information for instructing lowering of the transmission rate upper limit value is successively received a predetermined number of times or more during communication with a base station in the first communication system; and Switching from the first communication system to the second communication system when the determination result is that instruction information for instructing to lower the transmission rate has been successively received a predetermined number of times or more. 15. The communication method according to claim 14, wherein only when the transmission rate upper limit value in the first communication system is lower than a predetermined reference value, when the determination result is successively received equal to or more than a predetermined number of times The switching from the first communication system to the second communication system is performed when the instruction information is used for instructing to reduce the transmission rate. 16. The communication method according to claim 13 or 15, wherein the reference value is a value at which a transmission rate is expected to increase when communication is performed in the second communication system instead of the first communication system. 17. The communication method according to claim 13, comprising: deriving a remaining amount of data to be transmitted in said first communication system when the comparison result is that the upper limit value is lower than a reference value, Wherein switching from the first communication system to the second communication system is performed only when the derived remaining data amount is greater than a predetermined amount. 18. The communication method according to claim 14, comprising: deriving a remaining data amount to be transmitted in the first communication system when the determination result is that instruction information for instructing to lower the transmission rate has been successively received equal to or more than a predetermined number of times, Wherein switching from the first communication system to the second communication system is performed only when the derived remaining data amount is greater than a predetermined amount. 19. A wireless communication terminal connected to a connection base station holding information of peripheral base stations as handover destination candidates, the wireless communication terminal comprising: The receiving part is used to receive instruction information from surrounding base stations indicating to change the upper limit value of the transmission rate; a determining section for determining whether instruction information indicating to lower the upper limit value of the transmission rate is included in the instruction information received by the receiving section; a generating section for generating a signal of information for controlling peripheral base stations when the determination result obtained by the determining section includes instruction information indicating lowering of the transmission rate upper limit value; and a transmitting section for transmitting the signal generated by the generating section to the connecting base station. 20. The wireless communication terminal according to claim 19, wherein the signal for controlling the surrounding base station information includes information for removing from the information of the surrounding base stations a base station transmitting instruction information indicating lowering of the transmission rate upper limit value. 21. The wireless communication terminal according to claim 19, wherein the signal for controlling peripheral base station information is a value indicating communication quality between a base station transmitting instruction information indicating lowering of the transmission rate upper limit value and the wireless communication terminal, as well as Said value is lower than a predetermined reference value. 22. The wireless communication terminal according to claim 19, comprising: The export section, which is used to export the data volume of the data to be transferred, Wherein only when the amount of data derived by the deriving part is greater than a predetermined value, the transmitting part sends a message to the connecting base station when the determination result obtained by the determining part includes instruction information indicating to lower the upper limit value of the transmission rate Transmits a signal for controlling the information of surrounding base stations. 23. A program for use by a wireless communication terminal connected to a connected base station holding information of peripheral base stations as handover destination candidates, the program comprising: The first process is used to receive instruction information from surrounding base stations indicating to change the upper limit value of the transmission rate; A second process for determining whether instruction information indicating to lower the upper limit value of the transmission rate is included in the instruction information received by the receiving section; and A third procedure for transmitting a signal for controlling peripheral base station information to the connected base station when the determination result obtained by the determination section includes instruction information indicating lowering of the upper limit value of the transmission rate. 24. The program according to claim 23, wherein the signal for controlling the surrounding base station information includes removing information of a base station transmitting instruction information indicating lowering of the transmission rate upper limit value from the surrounding base station information. 25. The program according to claim 23, wherein the signal for controlling peripheral base station information is a value indicating communication quality between a base station transmitting instruction information indicating lowering of the transmission rate upper limit value and the wireless communication terminal, and Said value is lower than a predetermined reference value. 26. The program of claim 23, comprising: The fourth part, used to derive the data volume of the data to be transferred, In the third process, only when the remaining data amount derived by the fourth process is greater than a predetermined value, only when the determination result obtained by the second part includes instruction information indicating to reduce the upper limit value of the transmission rate , to transmit a signal for controlling the information of surrounding base stations to the connecting base station. 27. A communication method for use by a wireless communication terminal connected to a connection base station holding information of peripheral base stations that are handover destination candidates, the communication method comprising: receiving instruction information from surrounding base stations indicating to change the upper limit value of the transmission rate; determining whether instruction information for lowering the transmission rate upper limit value is included in the instruction information received by the receiving section; and When the determination result obtained by the determination section includes instruction information instructing to lower the transmission rate upper limit value, a signal for controlling peripheral base station information is transmitted to the connected base station. 28. The communication method according to claim 27, wherein the signal for controlling the surrounding base station information includes removing information of a base station transmitting instruction information indicating lowering of the transmission rate upper limit value from the surrounding base station information. 29. The communication method according to claim 27, wherein the signal for controlling the peripheral base station information is a value indicating the communication quality between the base station transmitting instruction information indicating lowering of the transmission rate upper limit value and the wireless communication terminal, and Said value is lower than a predetermined reference value. 30. The communication method according to claim 27, comprising: When the determination result includes instruction information indicating to reduce the upper limit value of the transmission rate, deriving the data amount of the data to be transmitted, Only when the amount of derived data is greater than a predetermined value, the signal for controlling the information of the surrounding base stations is transmitted to the connecting base station.

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