JP2010062680A - Communication system, mobile station device ,and communication method - Google Patents

Abstract

A communication system, a mobile station apparatus, and a communication method capable of reducing the number of signal transmissions from a mobile station apparatus to a base station apparatus and suppressing power consumption of the mobile station apparatus.
A mobile station apparatus that communicates with a base station apparatus, wherein the first signal transmission section transmits a first signal to the base station apparatus using a first frequency band, and a first signal transmission section. A response signal receiving unit that receives a response signal transmitted from the base station apparatus in response to the first signal transmitted by the base station, and a frequency band selection that selects the second frequency band based on the reception state of the response signal receiving unit And a second signal transmission unit that transmits the second signal to the base station apparatus using the second frequency band selected by the frequency band selection unit.
[Selection] Figure 1

Description

  The present invention relates to a communication system, a mobile station apparatus, and a communication method.

  Conventionally, in a CDMA (Code Division Multiple Access) communication system, a random access channel (RACH: Random Access Channel) is used to transmit a preamble signal at the time of random access when a mobile station apparatus moves from an idle state to a calling procedure. When transmitting to the base station apparatus, the preamble signal is transmitted by gradually increasing the transmission power several times until an acknowledgment (ACK signal) is transmitted from the base station apparatus.

  In addition, a similar random access method may be adopted in E-UTRA (Evolved Universal Terrestrial Radio Access) of 3GPP (The 3rd Generation Partnership Project: 3rd Generation Partnership Project). ing.

In a CDMA communication system, a preamble signal is transmitted from a mobile station apparatus to a base station apparatus using a random access channel (RACH) used when setting up a radio communication line between the mobile station apparatus and the base station apparatus, Thereafter, the base station apparatus establishes a radio link by receiving a random access channel (RACH) message.
At this time, the mobile station apparatus receives and sets information such as the maximum number of transmissions of the preamble signal and the initial transmission power from the base station apparatus, and then transmits the preamble signal to the base station apparatus. . Until the mobile station apparatus receives from the base station apparatus an acquisition indicator (AI) on the acquisition indicator channel (AICH) that returns an acknowledgment to the preamble signal transmitted by the mobile station apparatus, the mobile station apparatus transmits power. The power ramping process for transmitting a signal to the base station apparatus is performed.

A mobile station apparatus performs the following process, when an acknowledgment (ACK: ACKnowledgement) is received from a base station apparatus by the acquisition indicator channel (AICH). When the mobile station apparatus receives a negative acknowledgment (NACK) from the base station apparatus, the mobile station apparatus reports the reception of the negative acknowledgment (NACK) to the upper layer of the mobile station apparatus, and the random access channel (RACH) The transmission procedure using is terminated.
If the mobile station apparatus receives neither an acknowledgment (ACK) nor a negative acknowledgment (NACK) from the base station apparatus, the mobile station apparatus changes the access slot, signature, etc., and preambles up to the maximum number of transmissions. Repeat the signal transmission process. If no acknowledgment (ACK) or negative acknowledgment (NACK) is received from the base station apparatus, it is reported to the upper layer of the mobile station apparatus (Non-Patent Document 1).

In Patent Literature 1, when a message part is assigned to a preamble signal, a frequency band used for communication with the base station device is given priority to a mobile station device that has once received a negative acknowledgment (NACK) from the base station device. A technique for assigning the mobile station apparatus is disclosed.
In this Patent Document 1, for a mobile station apparatus that has once received a negative acknowledgment (NACK) from the base station apparatus, the base station apparatus estimates the mobile station apparatus from the propagation delay time of the preamble signal, and the mobile station apparatus On the other hand, the base station apparatus preferentially returns an acknowledgment (ACK) to reduce the number of preamble signal transmissions.

In 3GPP E-UTRA, the maximum system bandwidth is 20 MHz. When transmitting a preamble signal from the base station apparatus to the mobile station apparatus using such a wide system bandwidth, frequency hopping is performed in which two frequency bands for transmitting the preamble signal are alternately switched at a predetermined time interval. Thus, the radio link is established between the base station apparatus and the mobile station apparatus by the frequency diversity effect. In LTE (Long Term Evolution: 3G long-term evolution version), hopping at both ends of a frequency band has been studied (Non-Patent Document 2).
JP 2001-326978 A 3GPP standard (3GPP TS25.211) 3GPP TSG RAN1 # 51 R1-074606

  When a random access channel (RACH) preamble signal is transmitted from a mobile station device to a base station device in a communication system with a wide system bandwidth, it is difficult to communicate in a specific frequency band due to the influence of multipath, etc. If the frequency band overlaps with the frequency band for transmitting the preamble signal, even if the preamble signal is transmitted, it is difficult for the base station apparatus to receive the preamble signal transmitted by the mobile station apparatus when transmitting in that frequency band. .

In Non-Patent Document 2, when a frequency band used for communication between a mobile station apparatus and a base station apparatus is wide, communication may be difficult in a specific frequency band. In this case, if the negative response (NACK) is a frequency band returned from the base station apparatus, the mobile station apparatus can know that it is a frequency band in which communication is possible, but there is a frequency band in which communication is difficult. If the frequency band for hopping the preamble signal is included, the preamble signal is wastedly transmitted from the mobile station apparatus to the base station apparatus.
Also, in a frequency band where communication is difficult, the mobile station apparatus cannot receive a response to the preamble signal from the base station apparatus, and increases the transmission power by several dBm and transmits the preamble signal to the base station apparatus in the next slot. There is a possibility that the transmission power is increased unnecessarily.

  Further, in Patent Document 1, a negative response (NACK) is obtained when the base station device preferentially returns an acknowledgment (ACK) to a mobile station device that has received a previous negative response (NACK) from the base station device. Is returned, the communication success rate in the random access to the base station apparatus in the next and subsequent times is improved.

Thus, in the conventional technique, when a preamble signal is transmitted from the mobile station apparatus to the base station apparatus and a negative acknowledgment (NACK) is returned from the base station apparatus to the mobile station apparatus, the mobile station apparatus A ramping process for gradually increasing the transmission power of the signal or a frequency hopping process for switching the frequency band for transmitting the preamble signal at a predetermined time interval has been performed.
However, in the conventional technique, when the frequency band used when the mobile station apparatus transmits the preamble signal includes a frequency band that cannot be used for communication, the mobile station apparatus transmits the preamble signal to the base station many times in the frequency band. As a result, the number of transmissions of the preamble signal from the mobile station apparatus to the base station apparatus increases, and there is a problem that the power consumption of the mobile station apparatus increases.

  The present invention has been made in view of the above circumstances, and its purpose is to reduce the number of signal transmissions from the mobile station device to the base station device, thereby reducing the power consumption of the mobile station device, A mobile station apparatus and a communication method are provided.

(1) The present invention has been made to solve the above-described problem, and a communication system according to one aspect of the present invention is a communication system including a base station device and a mobile station device, wherein the mobile station device is A first signal transmission unit that transmits a first signal to the base station apparatus using a first frequency band, and the base station in response to the first signal transmitted by the first signal transmission unit. A response signal receiving unit that receives a response signal transmitted by the device; a frequency band selecting unit that selects a second frequency band based on a reception state of the response signal receiving unit; and a frequency band selecting unit selected by the frequency band selecting unit A second signal transmission unit that transmits the second signal to the base station apparatus using a second frequency band, wherein the base station apparatus transmits the first signal transmitted by the first signal transmission unit. A first signal receiving unit for receiving a signal and the first signal receiving unit; When receiving the first signal, a response signal transmitting unit that transmits a response signal to the mobile station device, and a second signal receiving unit that receives the second signal transmitted by the second signal transmitting unit. A part.

(2) A mobile station apparatus according to an aspect of the present invention is a mobile station apparatus that communicates with a base station apparatus, and transmits a first signal to the base station apparatus using a first frequency band. 1 signal transmission unit, a response signal reception unit that receives a response signal transmitted by the base station apparatus in response to the first signal transmitted by the first signal transmission unit, and reception by the response signal reception unit A second frequency band selecting unit that selects a second frequency band based on the state, and a second frequency band that is transmitted by the second frequency band selected by the frequency band selecting unit to the base station apparatus. The signal transmission part is provided.

(3) In addition, when the response signal reception unit receives a negative response from the base station device, the frequency band selection unit of the mobile station device according to an aspect of the present invention, as the second frequency band, The first signal transmission unit selects the same frequency band as the first frequency band used for transmitting the first signal.

(4) In addition, the frequency band selection unit of the mobile station apparatus according to one aspect of the present invention, when the response signal reception unit has not received an acknowledgment or a negative response from the base station apparatus for a predetermined time, As the second frequency band, the first signal transmission unit selects a frequency band different from the first frequency band used for transmitting the first signal.

(5) In the mobile station apparatus according to an aspect of the present invention, the first signal and the second signal are preamble signals.

(6) A communication method according to an aspect of the present invention is a communication method using a base station device and a mobile station device, and the mobile station device uses a first frequency band to transmit a first signal. And a response signal receiving process for receiving a response signal transmitted by the base station apparatus in response to the first signal transmitted in the first signal transmission process. And a frequency band selection process for selecting a second frequency band based on a reception state in the response signal reception process, and the second signal using the second frequency band selected in the frequency band selection process. A second signal transmission process for transmitting the first signal transmitted in the first signal transmission process to the base station apparatus, and a first signal reception process for receiving the first signal transmitted in the first signal transmission process. When the first signal is received in the first signal reception process It has a response signal transmission step of transmitting a response signal to the mobile station device, and a second signal receiving step of receiving the second signal transmitted by the second signal transmission process.

  In the communication system, mobile station apparatus, and communication method of the present invention, the number of signal transmissions from the mobile station apparatus to the base station apparatus can be reduced, and the power consumption of the mobile station apparatus can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The communication system according to the embodiment of the present invention includes a mobile station device 40 (FIG. 1) and a base station device 50 (FIG. 2). In this embodiment, a case where one mobile station device 40 and one base station device 50 are used will be described. However, the present invention is not limited to this, and a plurality of base station devices and mobile station devices are used. Also good.

  FIG. 1 is a schematic block diagram showing a configuration of a mobile station device 40 according to the embodiment of the present invention. The mobile station device 40 is a terminal such as a mobile phone, and includes a storage unit 41, a message decoding unit 42, a receiving unit 43, a preamble transmission frequency determining unit 44, a transmission timing adjusting unit 45, a transmitting unit 46, and an antenna unit 47. ing. FIG. 1 shows only the components of the mobile station apparatus 40 necessary for the description of the present embodiment, and other components are omitted.

  The storage unit 41 includes a memory, and information on the presence / absence of a reply message such as a negative response (NACK) returned from the base station apparatus 50 in response to the preamble signal transmitted to the base station apparatus 50 last time, or a reply message Information on the frequency band at the time of receiving, information on the number of transmissions of the preamble signal, information on whether or not the preamble signal transmission request to the base station apparatus 50 that transmits the preamble signal is the first time, and the like are stored.

The preamble transmission frequency determination unit 44 (also referred to as a frequency band selection unit) is a signal received by the reception unit 43 via the antenna unit 47 and is used based on the reception state of the signal transmitted by the base station device 50. A frequency band (second frequency band) is selected.
Specifically, the preamble transmission frequency determination unit 44 transmits the preamble signal from the mobile station device 40 to the base station device 50 based on the information stored in the storage unit 41 and the signal information received by the reception unit 43. Determine the frequency band to transmit. The preamble transmission frequency determination unit 44 outputs information on the determined frequency band to the transmission timing adjustment unit 45.

In addition, when the reception unit 43 receives a negative response (NACK) from the base station device 50 via the antenna unit 47, the preamble transmission frequency determination unit 44 sets the first frequency band to be used next as the first frequency band. The signal transmitter 46a selects the same frequency band (for example, frequency band f1) as the first frequency band (for example, frequency band f1) used for transmitting the preamble signal.
By performing such processing, the preamble can be retransmitted at a frequency with which communication has been achieved.

In addition, the preamble transmission frequency determination unit 44, when the reception unit 43 has not received an acknowledgment (ACK) or negative acknowledgment (NACK) from the base station device 50 for a predetermined time (for example, 10 seconds), As the frequency band, the first signal transmission unit 46a selects a frequency band (for example, frequency band f2) different from the first frequency band (for example, frequency band f1) used for transmitting the preamble signal.
By performing such processing, for example, a preamble signal is transmitted from the mobile station device 40 to the base station device 50, but there is no response from the base station device 50 to the mobile station device 40 due to some communication situation. However, the preamble signal can be retransmitted using a second frequency band different from the first frequency band. Therefore, the preamble signal can be retransmitted from the mobile station device 40 to the base station device 50 using a plurality of frequency bands, and communication between the mobile station device 40 and the base station device 50 can be established. Can be increased.

  The transmission timing adjustment unit 45 adjusts the transmission timing up to the slot for transmitting the preamble signal to the base station apparatus 50 using the frequency band determined by the preamble transmission frequency determination unit 44. The transmission timing adjustment unit 45 outputs a signal to be transmitted from the mobile station device 40 to the base station device 50 such as a preamble signal at the adjusted transmission timing.

The transmission unit 46 includes a first signal transmission unit 46a and a second signal transmission unit 46b, and performs a modulation process on a signal transmitted from the mobile station device 40 to the base station device 50, such as a preamble signal. After performing the up-conversion process, the data is transmitted to the base station apparatus 50 via the antenna unit 47 at the transmission timing adjusted by the transmission timing adjustment unit 45.
The first signal transmission unit 46a transmits a preamble signal (also referred to as a first signal) to the base station device 50 via the antenna unit 47 using the first frequency band (for example, the frequency band f1). .
The second signal transmission unit 46b uses the second frequency band (for example, the frequency band f1 or the frequency band f2) selected by the preamble transmission frequency determination unit 44 to generate a preamble signal (also referred to as a second signal). The data is transmitted to the base station device 50 via the antenna unit 47.

The receiving unit 43 (also referred to as a response signal receiving unit) performs down-conversion and demodulation processing to a baseband signal after receiving the signal transmitted from the base station device 50 such as a response signal to the mobile station device 40. After that, the message is output to the message decoding unit 42.
The reception unit 43 responds to the preamble signal transmitted from the first signal transmission unit 46a to the base station device 50, and transmits a response signal (acknowledgment (ACK) or negative response (NACK) transmitted by the base station device 50). ) Is received via the antenna unit 47 and output to the message decoding unit 42.
The message decryption unit 42 decrypts the message included in the signal output from the reception unit 43 and records the decryption result in the storage unit 41. The message decryption unit 42 determines whether the signal output from the reception unit 43 includes an acknowledgment (ACK) or a negative response (NACK).

  FIG. 2 is a schematic block diagram showing the configuration of the base station apparatus 50 according to the embodiment of the present invention. The base station device 50 includes a reception unit 51, a preamble decoding unit 52, a control unit 53, a transmission unit 54, and an antenna unit 55. Note that FIG. 2 shows only the components of the base station apparatus 50 necessary for the description of the present embodiment, and other components are omitted.

The receiving unit 51 includes a first signal receiving unit 51a and a second signal receiving unit 51b. A base station after receiving a signal transmitted from the mobile station device 40 such as a preamble signal to the base station device 50. After down-conversion to a band signal and demodulation processing, the signal is output to the preamble decoding unit 52.
The first signal reception unit 51 a receives the preamble signal transmitted by the first signal transmission unit 46 a of the mobile station device 40 via the antenna unit 55 and outputs it to the preamble decoding unit 52.
The second signal reception unit 51 b receives the preamble signal transmitted by the second signal transmission unit 46 b of the mobile station device 40 via the antenna unit 55 and outputs it to the preamble decoding unit 52.

  If the preamble signal is included in the signal output from the receiving unit 51, the preamble decoding unit 52 extracts the preamble signal, determines whether the preamble signal satisfies a predetermined condition, and determines the determination. The result is output to the control unit 53. For example, the preamble decoding unit 52 determines whether or not the reception power of the preamble signal in the base station device 50 is larger than a predetermined value.

The control unit 53 acquires a signal transmitted from the base station device 50 to the mobile station device 40 from an upper layer (not shown) of the base station device 50 and outputs the signal to the transmission unit 54.
Further, the control unit 53 generates a response signal such as an acknowledgment (ACK) or a negative response (NACK) based on the determination result output by the preamble decoding unit 52 and outputs the response signal to the transmission unit 54.
For example, when the determination result that the received power of the preamble signal at the base station apparatus 50 is larger than a predetermined value is output from the preamble decoding unit 52, an acknowledgment (ACK) is output to the transmitting unit 54.
On the other hand, when the determination result that the received power of the preamble signal at the base station apparatus 50 is equal to or less than the predetermined value is output from the preamble decoding unit 52, a negative response (NACK) is output to the transmitting unit 54.

The transmission unit 54 (also referred to as a response signal transmission unit) performs a modulation process or an up-conversion process to a radio frequency on a signal transmitted from the base station apparatus 50 to the mobile station apparatus 40 such as a response signal. Then, the data is transmitted to the mobile station device 40 via the antenna unit 55.
In addition, when the first signal reception unit 51a receives the preamble signal, the transmission unit 54 transmits a response signal (acknowledgment (ACK) or negative response (NACK)) output from the control unit 53 to the antenna unit 55. To the mobile station device 40.

FIG. 3 is a diagram illustrating a configuration of a signal transmitted from the mobile station device 40 to the base station device 50 according to the embodiment of the present invention. In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates frequency.
In FIG. 3, twelve slots are arranged in the time axis direction. In FIG. 3, a plurality of frequency bands (frequency band f0, frequency band f1,..., Frequency band f2, frequency band f3) are arranged in the frequency axis direction.

An uplink control channel (PUCCH) is arranged in each of the first to twelfth slots in the frequency band f0.
The uplink control channel (PUCCH) is also arranged in each of the first to twelfth slots in the frequency band f3 region.

A random access channel (RACH) is arranged in the second slot in the frequency band f1 region. A random access channel (RACH) is also arranged in the eighth slot in the frequency band f1 region.
A random access channel (RACH) is arranged in the fifth slot in the frequency band f2. A random access channel (RACH) is also arranged in the eleventh slot in the frequency band f2.

In FIG. 3, an uplink shared channel (PUSCH: Physical Up Shared Channel) is arranged in each region where no uplink control channel (PUCCH) or random access channel (RACH) is arranged.
The frequency band in which the preamble signal can be transmitted is determined in advance between the mobile station apparatus 40 and the base station apparatus 50, and in this embodiment, is the frequency band f1 or the frequency band f2.
There are 16 configurations for the slots for transmitting the random access channel (RACH). The preamble signal is transmitted from the mobile station device 40 to the base station device 50 using the random access channel (RACH) region of FIG.

  4, 5 and 6 are flowcharts showing processing of the mobile station apparatus 40 according to the embodiment of the present invention. 4 is a flowchart showing the processes of steps S101, S102, and S104 to S115, FIG. 5 is a flowchart showing the processes of steps S201 to S203, and FIG. 6 shows the processes of steps S301 to S307. It is a flowchart. Note that transmitting a preamble signal from the mobile station device 40 to the base station device 50 using the frequency band f1 or the frequency band f2 between the mobile station device 40 and the base station device 50 means that the mobile station device 40 and the base station 50 Before the device 50 starts communication, the mobile station device 40 and the base station device 50 are set.

  First, the preamble transmission frequency determination unit 44 initializes information stored in the storage unit 41 (step S101 in FIG. 4). That is, a flag indicating that the transmission process of the preamble signal transmitted from the mobile station apparatus 40 to the base station apparatus 50 is the first time is set (S = 1). Further, the number of times that the mobile station device 40 has received a negative response (NACK) from the base station device 50 is set to 0 (NACK = 0). Further, the number of times the preamble signal is transmitted from the mobile station device 40 to the base station device 50 is set to 0 (N = 0).

Then, the preamble transmission frequency determination unit 44 obtains a preamble transmission request signal instructing to transmit a preamble signal from the mobile station device 40 to the base station device 50 from an upper layer (not shown) of the mobile station device 40 ( Step S102 in FIG. 4).
The preamble transmission frequency determination unit 44 then stores whether the flag indicating that the transmission process of the preamble signal transmitted from the mobile station device 40 to the base station device 50 is the first time is not set, that is, the storage unit 41 stores the flag. Whether or not S is 0 is determined (step S104 in FIG. 4).

  When the transmission process of the preamble signal transmitted from the mobile station device 40 to the base station device 50 is the first time, that is, when the flag S stored in the storage unit 41 is 1, the preamble transmission frequency determination unit 44 performs the step In S104, “NO” is determined, and the process of step S201 in FIG. 5 is performed. That is, the preamble transmission frequency determination unit 44 selects the nearest slot that can be transmitted (step S201 in FIG. 5), sets the transmission frequency band of the selected transmission slot to fnew (step S202 in FIG. 5), and the storage unit 41. Is cleared by setting S = 0 to the initial transmission count flag S (step S203 in FIG. 5), and then the process of step S114 in FIG. 4 is performed.

Then, the preamble transmission frequency determination unit 44 updates the frequency band forg stored in the storage unit 41 to fnew (step S114 in FIG. 4).
And the transmission part 46 transmits a preamble signal to the base station apparatus 50 using the frequency band forg which the memory | storage part 41 has memorize | stored (step S115 of FIG. 4).
After transmitting the preamble signal to the base station device 50 in step S115, the receiving unit 43 waits for a reply from the base station device 50.
The message decoding unit 42 determines whether or not the signal returned from the base station device 50 and received by the receiving unit 43 via the antenna unit 47 includes an acknowledgment (ACK) ( Step S301 in FIG. If the signal received from the base station device 50 includes an acknowledgment (ACK), the message decoding unit 42 determines “YES” in step S301, and the preamble signal from the mobile station device 40 to the base station device 50 is determined. The transmission process is terminated.

  On the other hand, if the signal received from the base station device 50 does not include an acknowledgment (ACK), the message decoding unit 42 determines “NO” in step S301, and performs the process of step S302. That is, the message decoding unit 42 determines whether or not a negative response (NACK) is included in the signal returned from the base station device 50 and received by the receiving unit 43 via the antenna unit 47. (Step S302 in FIG. 6).

If a negative response (NACK) is included in the signal received from the base station device 50, the message decoding unit 42 determines “YES” in step S302, and the message decoding unit 42 sends a negative response to the storage unit 41. Record the reception history of (NACK). That is, the message decoding unit 42 updates the number of transmissions N stored in the storage unit 41 to 0, and updates the number NACK of receptions of negative acknowledgment (NACK) stored in the storage unit 41 to 1 (see FIG. 6 step S307). And it progresses to the process of step S102 of FIG. 4, and waits for the preamble resending request signal to be output from the upper layer of the mobile station apparatus 40.
Note that the upper layer of the mobile station device 40 outputs a preamble transmission request signal to the preamble transmission frequency determination unit 44 when the number of negative acknowledgment (NACK) reception times reaches a predetermined number (for example, five times). The preamble transmission request signal may be output to the preamble transmission frequency determination unit 44 after stopping or waiting for a certain time (for example, 5 minutes).

  In step S302 of FIG. 6, when the signal received from the base station apparatus 50 during the predetermined time interval does not include a negative acknowledgment (NACK), the message decoding unit 42 determines “NO”, and the step The process of S303 is performed. That is, the preamble transmission frequency determination unit 42 determines whether or not the number N of preamble signal transmissions from the mobile station device 40 to the base station device 50 has reached the maximum number of transmissions MAX (for example, MAX = 10) ( Step S303 in FIG. 6).

If the number of transmissions N has reached the maximum number of transmissions MAX, the preamble transmission frequency determination unit 44 determines “YES” in step S303 and reports to the upper layer of the mobile station device 40 (step S306 in FIG. 6). Then, the transmission process of the preamble signal from the mobile station device 40 to the base station device 50 is terminated.
On the other hand, if the number of transmissions N has not reached the maximum number of transmissions MAX, the preamble transmission frequency determination unit 44 determines “NO” in step S303, and adds 1 to the number of transmissions N stored in the storage unit 41. (Step S304 in FIG. 6), power ramping processing is performed to increase the transmission power of the preamble signal transmitted from the mobile station device 40 to the base station device 50 by a predetermined amount (Step S305 in FIG. 6), and Step S104 in FIG. Perform the process.

  When the transmission process of the preamble signal transmitted from the mobile station device 40 to the base station device 50 is not the first time, that is, when the flag S stored in the storage unit 41 is not 1, the preamble transmission frequency determination unit 44 In step S104 of FIG. 4, “YES” is determined, and the process of step S105 is performed. That is, the preamble transmission frequency determination unit 44 determines whether or not a negative acknowledgment (NACK) reception history is recorded in the storage unit 41. That is, the preamble transmission frequency determination unit 44 determines whether or not there is a negative response (NACK) from the base station device 50 (whether NACK is 1) in the mobile station device 40 (step S105 in FIG. 4).

When the reception record is present (NACK is 1) in the storage unit 41, the preamble transmission frequency determination unit 44 determines “YES” in step S105, and performs the process of step S106. That is, the preamble transmission frequency determination unit 44 updates the reception count NACK recorded in the storage unit 41 to 0 (step S106 in FIG. 4).
Then, the preamble transmission frequency determination unit 44 determines whether or not the frequency band forg recorded in the storage unit 41 is f1 (step S107 in FIG. 4).

When the frequency band forg recorded in the storage unit 41 is f1, the preamble transmission frequency determination unit 44 determines “YES” in step S107, and performs the process of step S108. That is, the preamble transmission frequency determination unit 44 selects the frequency band f1 as the transmission frequency band fnew of the preamble signal to be transmitted next time from the mobile station apparatus 40 to the base station apparatus 50 (step S108 in FIG. 4), and proceeds to step S113. .
On the other hand, if the frequency band forg recorded in the storage unit 41 is not f1, the preamble transmission frequency determination unit 44 determines “NO” in step S107, and performs the process of step S109. That is, the preamble transmission frequency determination unit 44 selects the frequency band f2 as the transmission frequency band fnew of the preamble signal to be transmitted next time from the mobile station apparatus 40 to the base station apparatus 50 (step S109 in FIG. 4), and proceeds to step S113. .

If the reception count NACK recorded in the storage unit 41 is not 1, the preamble transmission frequency determination unit 44 determines “NO” in step S105, and performs the process of step S110. That is, the preamble transmission frequency determination unit 44 determines whether or not the frequency band forg recorded in the storage unit 41 is f1 (step S110 in FIG. 4).
If the frequency band forg recorded in the storage unit 41 is f1, the preamble transmission frequency determination unit 44 determines “YES” in step S110, and performs the process of step S111. That is, the preamble transmission frequency determination unit 44 selects the frequency band f2 as the transmission frequency band fnew of the preamble signal to be transmitted next time from the mobile station apparatus 40 to the base station apparatus 50 (step S111 in FIG. 4), and proceeds to step S113. .

  On the other hand, if the frequency band forg recorded in the storage unit 41 is not f1, the preamble transmission frequency determination unit 44 determines “NO” in step S110, and performs the process of step S112. That is, the preamble transmission frequency determination unit 44 selects the frequency band f1 as the transmission frequency band fnew of the preamble signal to be transmitted next time from the mobile station apparatus 40 to the base station apparatus 50 (step S112 in FIG. 4), and proceeds to step S113. .

After performing any one of steps S108, S109, S111, and S112, the transmission timing adjustment unit 45 waits until a slot for transmitting a preamble signal from the mobile station device 40 to the base station device 50 using the transmission frequency band fnew. (Step S113 in FIG. 4).
Then, the preamble transmission frequency determination unit 44 updates the frequency band forg recorded in the storage unit 41 to the frequency band fnew (step S114 in FIG. 4).
And the transmission part 46 transmits a preamble signal to the base station apparatus 50 using the frequency band forg which the memory | storage part 41 has memorize | stored (step S115 of FIG. 4).

According to the present embodiment, a plurality of frequency bands f1 and f2 used for transmitting a preamble signal are set in advance in each of the mobile station device and the base station device between the mobile station device 40 and the base station device 50. When the preamble signal is transmitted from the mobile station device 40 to the base station device 50 using a predetermined frequency band (for example, the frequency band f1), the response signal is not obtained from the base station device 50. Is transmitted from the mobile station device 40 to the base station device 50 using a different frequency band (for example, frequency band f2) from the previous transmission.
Therefore, a preamble signal can be transmitted from the mobile station device 40 to the base station device 50 while avoiding a frequency band that cannot be used for communication between the mobile station device 40 and the base station device 50. By reducing the number of times the preamble signal is transmitted to the station device 50, a wireless connection can be established early between the mobile station device 40 and the base station device 50, and power consumption of the mobile station device 40 can be suppressed. it can. In addition, it is possible to eliminate retransmission of the preamble signal from the mobile station device 40 to the base station device 50 over and over using a frequency band that cannot be used for communication between the mobile station device 40 and the base station device 50. Use of unnecessary radio resources can be avoided.

  In the above-described embodiment, the case where the mobile station device 40 selects the frequency band used when transmitting the preamble signal to the base station device 50 from the two frequency bands f1 and f2 has been described. It is not limited. For example, the frequency band used when the mobile station apparatus 40 transmits a preamble signal to the base station apparatus 50 may be selected from three or more frequency bands.

For example, the frequency band used when the mobile station apparatus 40 transmits a preamble signal to the base station apparatus 50 is selected from three frequency bands f01, f02, and f03 (where f01 <f02 <f03). Also good. In this case, when the preamble signal is transmitted from the mobile station device 40 to the base station device 50 for the first time using the frequency band f01, but the response signal is not returned from the base station device 50, the frequency fluctuation range is reduced. Thus, it is preferable to select a frequency band for transmitting the preamble signal next time.
Here, since the fluctuation range from the frequency band f01 to the frequency band f02 is smaller than the fluctuation range from the frequency band f01 to the frequency band f03, the preamble transmission frequency determination unit 44 performs the transmission from the mobile station device 40 to the base station device. When the preamble signal is retransmitted to 50, the frequency band f02 is selected.

  In the embodiment described above, a program for realizing the function of each unit of the mobile station device 40 of FIG. 1 or each unit of the base station device 50 of FIG. 2 is recorded on a computer-readable recording medium. The mobile station apparatus and the base station apparatus may be controlled by causing a computer system to read and execute a program recorded on a recording medium. Here, the “computer system” includes an OS and hardware such as peripheral devices.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case is also used to hold a program for a certain period of time. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the design and the like within the scope of the present invention are also within the scope of the claims. include.

It is a schematic block diagram which shows the structure of the mobile station apparatus 40 by embodiment of this invention. It is a schematic block diagram which shows the structure of the base station apparatus 50 by embodiment of this invention. It is a figure which shows the structure of the signal which the mobile station apparatus 40 by embodiment of this invention transmits to the base station apparatus 50. FIG. It is a flowchart which shows the process of the mobile station apparatus 40 by embodiment of this invention. It is a flowchart which shows the process of the mobile station apparatus 40 by embodiment of this invention. It is a flowchart which shows the process of the mobile station apparatus 40 by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 40 ... Mobile station apparatus, 41 ... Memory | storage part, 42 ... Message decoding part, 43 ... Reception part, 44 ... Preamble transmission frequency determination part, 45 ... Transmission timing adjustment part, 46 Transmission unit 46a First signal transmission unit 46b Second signal transmission unit 47 Antenna unit 50 Base station device 51 Reception unit 51a ... first signal receiving unit, 51b ... second signal receiving unit, 52 ... preamble decoding unit, 53 ... control unit, 54 ... transmitting unit, 55 ... antenna unit

Claims (6)

A communication system comprising a base station device and a mobile station device,
The mobile station device
A first signal transmission unit that transmits a first signal to the base station apparatus using a first frequency band;
A response signal receiving unit that receives a response signal transmitted by the base station apparatus in response to the first signal transmitted by the first signal transmitting unit;
A frequency band selecting unit that selects a second frequency band based on the reception state of the response signal receiving unit;
A second signal transmission unit that transmits the second signal to the base station apparatus using the second frequency band selected by the frequency band selection unit;
The base station device
A first signal receiver that receives the first signal transmitted by the first signal transmitter;
A response signal transmitting unit that transmits a response signal to the mobile station device when the first signal receiving unit receives the first signal;
A communication system, comprising: a second signal receiving unit that receives the second signal transmitted by the second signal transmitting unit. A mobile station device that communicates with a base station device,
A first signal transmission unit that transmits a first signal to the base station apparatus using a first frequency band;
A response signal receiving unit that receives a response signal transmitted by the base station apparatus in response to the first signal transmitted by the first signal transmitting unit;
A frequency band selecting unit that selects a second frequency band based on the reception state of the response signal receiving unit;
A second signal transmission unit that transmits the second signal to the base station device using the second frequency band selected by the frequency band selection unit;
A mobile station apparatus comprising:   When the response signal receiving unit receives a negative response from the base station apparatus, the frequency band selecting unit transmits the first signal as the second frequency band by the first signal transmitting unit. The mobile station apparatus according to claim 2, wherein the same frequency band as the first frequency band used in the selection is selected.   When the response signal receiving unit has not received an acknowledgment or a negative response from the base station apparatus for a predetermined time, the frequency band selecting unit sets the first signal transmitting unit as the second frequency band. The mobile station apparatus according to claim 2 or 3, wherein a frequency band different from the first frequency band used for transmission of the first signal is selected.   The mobile station apparatus according to any one of claims 2 to 4, wherein the first signal and the second signal are preamble signals. A communication method using a base station device and a mobile station device,
The mobile station device
A first signal transmission process of transmitting a first signal to the base station apparatus using a first frequency band;
A response signal receiving process of receiving a response signal transmitted by the base station apparatus in response to the first signal transmitted in the first signal transmitting process;
A frequency band selection process of selecting a second frequency band based on a reception state in the response signal reception process;
A second signal transmission process of transmitting the second signal to the base station apparatus using the second frequency band selected in the frequency band selection process,
The base station device
A first signal receiving process for receiving the first signal transmitted in the first signal transmitting process;
A response signal transmission process for transmitting a response signal to the mobile station apparatus when the first signal is received in the first signal reception process;
And a second signal receiving process for receiving the second signal transmitted in the second signal transmitting process.

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