JP4753804B2 - Base station apparatus and communication restriction method - Google Patents

Description

  The present invention relates to a base station apparatus and a communication restriction method, and more particularly to a technique for suppressing occurrence of an error in communication of a multiplexed mobile station apparatus at the start of multiplexing in a space division multiplexing system.

  In a mobile communication system, a mobile station apparatus communicates with a base station apparatus using one or more link channels. This link channel is specified by a frequency and a time slot in an example of a mobile communication system that multiplexes communication by frequency division multiplexing and time division multiplexing.

  When the mobile station apparatus attempts to communicate with the base station apparatus using a new link channel, the mobile station apparatus performs a process called carrier sense. Carrier sense is a process for confirming that the link channel to be used is not used by another mobile station apparatus. The mobile station apparatus performs the carrier sense by detecting a communication radio wave at a frequency and a time slot that specify a link channel to be used.

  If a communication radio wave is detected as a result of the carrier sense, the mobile station apparatus determines that the link channel to be used is being used by another mobile station apparatus. In this case, the mobile station apparatus does not start communication on the link channel.

  By the way, some mobile communication systems share the above-described link channel among a plurality of mobile station apparatuses by a space division multiplexing method. When space division multiplexing is started, a link channel (link channel targeted for carrier sense) that a mobile station apparatus (referred to as a multiplexing-side mobile station apparatus) intends to use from now on is another mobile station apparatus (multiplexed side). Called a mobile station device). For this reason, when the multiplex side mobile station apparatus performs the carrier sense, a communication radio wave is detected, and the multiplex side mobile station apparatus does not start communication on the link channel.

Since this does not start space division multiplexing, the base station apparatus limits communication of the multiplexed mobile station apparatus while the multiplexing mobile station apparatus performs carrier sense. As a specific example, in the technique described in Patent Literature 1, transmission to the multiplexed mobile station apparatus is stopped. In the technique described in Patent Document 2, the null point of the transmission radio wave to the multiplexed mobile station device is directed toward the multiplexing mobile station device.
JP 2004-248001 A JP 2001-268004 A

  If such a restriction is performed, an error may occur in the communication of the multiplexed mobile station device as a result. For this reason, it is desirable that the above limitation be performed only for a truly necessary time (that is, a time during which the multi-side mobile station apparatus performs carrier sense). Even if there was no time, there was a case where the above-mentioned restriction was performed.

  That is, in actual processing, first, the base station apparatus allocates a link channel to the multi-side mobile station apparatus. The multi-side mobile station apparatus starts carrier sense upon receiving this assignment, but since the time from the start of assignment to the start of carrier sense depends on the processing capability of the multi-side mobile station apparatus, the base station apparatus The above restriction must be started according to the multiplex side mobile station apparatus having the shortest time. Therefore, the base station apparatus may have performed the above restriction even though the carrier sense has not yet started in the multiplexing side mobile station apparatus.

  Accordingly, one of the objects of the present invention is to provide a base station apparatus and a communication restriction method capable of starting the restriction in accordance with the timing at which the multiplex side mobile station apparatus starts carrier sense.

  In order to solve the above problems, a base station apparatus according to the present invention transmits an instruction signal for instructing carrier sense of a specific link channel to a first mobile station apparatus communicating with the base station apparatus. The instruction signal transmission means, carrier sense start timing acquisition means for acquiring a carrier sense start timing indicating a timing at which the first mobile station apparatus starts carrier sense in response to the instruction signal, and the instruction signal A communication restriction start means for starting restriction of communication at a timing corresponding to the carrier sense start timing acquired by the carrier sense start timing acquisition means for the second mobile station apparatus communicating in the link channel; and When the mobile station apparatus completes carrier sense, the communication restriction start means Characterized in that it contains to a communication restriction release means for releasing the communication restriction has, the.

  According to this, the base station device restricts communication of the second mobile station device (multiplexed-side mobile station device) at the timing when the first mobile station device (multiplex-side mobile station device) starts carrier sense. Can start.

  Further, in the base station apparatus, a timing at which the instruction signal is transmitted to the first mobile station apparatus by the instruction signal transmission means, and a predetermined signal indicating completion of carrier sense from the first mobile station apparatus are provided. Based on the received timing, a carrier sense for acquiring a carrier sense start required time indicating a time required for the first mobile station apparatus to start carrier sense after transmission of the instruction signal by the instruction signal transmission means And a storage means for storing the start required time acquisition means, the information indicating the first mobile station apparatus, and the carrier sense start required time acquired by the carrier sense start required time acquisition means in association with each other. And the carrier sense start timing acquisition means is associated with information indicating the first mobile station apparatus by the storage means. A carrier sense start required time is, the timing of transmitting the instruction signal by the instruction signal transmitting means, based on, for obtaining the carrier sense start timing, it is also possible.

  According to this, the carrier sense start timing acquisition means can acquire the carrier sense start timing based on the past results.

  In the base station apparatus, the carrier sense start timing acquisition means further includes the instruction signal when the storage means does not store a carrier sense start required time in association with information indicating the first mobile station apparatus. The timing according to the timing at which the instruction signal is transmitted by the transmission means may be acquired as the carrier sense start timing.

  According to this, the base station apparatus can make the timing according to the timing which transmitted the instruction | indication signal the carrier sense start timing, when the carrier sense start required time is not memorize | stored yet.

  The base station apparatus control method according to the present invention provides an instruction signal for instructing carrier sense of a specific link channel from the base station apparatus to the first mobile station apparatus communicating with the base station apparatus. An instruction signal transmission step for transmitting, a carrier sense start timing acquisition step for acquiring a carrier sense start timing indicating a timing at which the first mobile station apparatus starts carrier sense in response to the instruction signal, and a specification by the instruction signal A communication restriction start step for starting restriction of the communication at a timing corresponding to the carrier sense start timing acquired in the carrier sense start timing acquisition step for the second mobile station apparatus that is communicating in the link channel to be transmitted; When the first mobile station apparatus completes the carrier sense, And releasing the communication restriction step of releasing the restriction of the communication initiated by Shin restriction start step, characterized in that it comprises a.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a system configuration of a mobile communication system 1 according to the present embodiment. As shown in the figure, the mobile communication system 1 includes a base station device 10 and a mobile station device 30.

  Each of the base station device 10 and the mobile station device 30 is a computer including a CPU and a memory. The CPU is a processing unit for executing a program stored in the memory, performs processing for controlling each unit of each device, and implements each functional unit described later. The memory stores programs and data for carrying out the present embodiment. It also operates as a work memory for the CPU.

  The base station apparatus 10 communicates with a plurality of mobile station apparatuses 30 simultaneously using frequency division multiplexing and time division multiplexing. A channel specified by frequency and time slot is called a link channel.

  The base station apparatus 10 causes a plurality of mobile station apparatuses 30 to use one link channel at the same time using multiplexing by space division multiplexing. Spatial division multiplexing uses the directivity of radio waves so that the radio waves do not interfere with each other.

  The triggers for starting space division multiplexing are as follows. That is, when the link channel is not empty, and when a link channel establishment request is further received from a new mobile station device 30, the base station device 10 determines that one of the mobile station devices 30 already in communication is The mobile station apparatus 30 that has transmitted the link channel establishment request is multiplexed by space division multiplexing. Alternatively, two of the mobile station devices 30 that are already communicating may be multiplexed by space division multiplexing, and a free link channel may be assigned to the mobile station device 30 that has transmitted a link channel establishment request.

  In any case, when space division multiplexing is started in this way, the base station apparatus 10 connects to any one of the mobile station apparatuses 30 in communication (multiplexed-side mobile station apparatus 30) with another mobile station apparatus. 30 (multiplexing side mobile station apparatus 30) is multiplexed. Since a new link channel is allocated to the multiplex side mobile station apparatus 30, the multiplex side mobile station apparatus 30 performs carrier sense. The base station device 10 limits the communication of the multiplexed mobile station device 30 while the carrier sense is performed so that the carrier sense is successful. In this embodiment, the base station device 10 uses the multiplexed mobile station device. It is realized that communication restriction of the multiplexed mobile station device 30 is started in accordance with the timing at which 30 starts carrier sense. Hereinafter, the configuration for this will be described in detail.

  FIG. 2 is a diagram illustrating functional blocks of the base station apparatus 10. As shown in the figure, the base station apparatus 10 functionally includes a demodulator 11, a link channel establishment request receiver 12, a link channel assignment transmitter 13, a modulator 14, a carrier sense start timing acquisition unit 15, and transmission weight control. Unit 16, link channel assignment transmission time acquisition unit 17, carrier sense start required time acquisition unit 18, synchronization burst reception unit 19, synchronization burst reception time acquisition unit 20, storage unit 21, and antenna 22.

  The demodulator 11 demodulates a radio signal received by the antenna 22 and outputs the demodulated signal to a communication processing unit (not shown). The antenna 22 is an adaptive array antenna, and a reception weight calculation unit (not shown) calculates a reception weight indicating a difference in amplitude and phase between antenna elements.

  The modulation unit 14 receives and modulates communication data from a communication processing unit (not shown), multiplies the transmission weight according to the reception weight, and then wirelessly transmits from each antenna element constituting the antenna 22. .

  The link channel establishment request receiving unit 12 receives the link channel establishment request transmitted from the multiplexing-side mobile station device 30. Upon receiving this link channel establishment request, the base station apparatus 10 determines whether or not it is necessary to perform space division multiplexing between the multiplexing-side mobile station apparatus 30 and another mobile station apparatus 30.

  When it is determined that there is no need for space division multiplexing, the base station device 10 secures a link channel that is not used by another mobile station device 30 and indicates the secured link channel to the link channel assignment transmitter 13. Instructs to send link channel assignments.

  When determining that it is necessary to perform space division multiplexing, the base station apparatus 10 instructs the link channel assignment transmission unit 13 to use the link channel (hereinafter referred to as a multiplexing target link channel) used by the multiplexed mobile station apparatus 30. To send a link channel assignment indicating.

  The link channel assignment transmission unit 13 generates a link channel assignment which is an instruction signal for instructing carrier sense of a specific link channel according to the instruction, and outputs the link channel assignment to the modulation unit 14. The modulation unit 14 modulates the input link channel assignment, and wirelessly transmits to each of the multiple-side mobile station devices 30 from each antenna element constituting the antenna 22.

  The link channel assignment transmission time acquisition unit 17 acquires a time indicating the timing at which the link channel assignment is transmitted to the multiplexing-side mobile station apparatus 30.

  The synchronization burst receiving unit 19 receives the synchronization burst when the multiplexing-side mobile station apparatus 30 that has completed the carrier sense transmits a synchronization burst (a predetermined signal indicating the completion of the carrier sense). The synchronization burst reception time acquisition unit 20 acquires a time indicating the reception timing of the synchronization burst received in this way.

  The carrier sense start required time acquisition unit 18 is based on the time acquired by the link channel allocation transmission time acquisition unit 17 and the time acquired by the synchronization burst reception time acquisition unit 20. Sense start required time (time required until the multiplexing side mobile station apparatus 30 starts carrier sense after transmission of link channel assignment) is acquired. In obtaining the carrier sense start required time, the time required for executing the carrier sense and the time required for transmitting the synchronization burst after the completion of the carrier sense are not different for each mobile station device 30, and these are set as constants. Then, a value obtained by subtracting the constant from the elapsed time from the time acquired by the link channel allocation transmission time acquisition unit 17 to the time acquired by the synchronization burst reception time acquisition unit 20 is obtained as a multiplex side mobile station device 30. Obtained as the required time for starting carrier sense.

  The carrier sense start required time acquisition unit 18 also calculates the elapsed time from the time acquired by the link channel allocation transmission time acquisition unit 17 to the time acquired by the synchronization burst reception time acquisition unit 20 to the multiplexing-side mobile station device 30. As the mobile station apparatus response time.

  The carrier sense start required time acquisition unit 18 writes the carrier sense start required time and the mobile station apparatus response time acquired in this way in the carrier sense information table of the storage unit 21 in association with the identification information of the multiplexing side mobile station apparatus 30. .

  FIG. 3 is a diagram showing an example of this carrier sense information table. As shown in the figure, in the carrier sense information table, mobile station apparatus identification information and carrier sense information (mobile station apparatus response time and carrier sense start required time) are stored in association with each other.

  Next, the carrier sense start timing acquisition unit 15 acquires the carrier sense start timing indicating the timing at which the multiplexing-side mobile station apparatus 30 starts carrier sense in accordance with the link channel assignment. Specifically, the carrier sense start timing acquisition unit 15 stores the carrier sense start required time stored in association with the identification information of the multiplexing-side mobile station device 30 by the carrier sense information table, and the timing at which the link channel assignment is transmitted. Based on, carrier sense start timing is obtained. More specifically, the timing after the time required for the carrier sense start is acquired as the carrier sense start timing from the time indicating the timing at which the link channel assignment is transmitted.

  Note that there may be a case where the carrier sense start required time is not stored in the carrier sense information table in association with the identification information of the multiplexing-side mobile station device 30. In this case, the carrier sense start timing acquisition unit 15 acquires a timing corresponding to the timing at which the link channel assignment is transmitted as the carrier sense start timing. In a specific example, the timing after the elapse of a predetermined time from the timing at which link channel allocation is transmitted is acquired as the carrier sense start timing.

  The transmission weight control unit 16 starts limiting communication of the multiplexed mobile station device 30 at a timing corresponding to the carrier sense start timing acquired by the carrier sense start timing acquisition unit 15. Specifically, simultaneously with the arrival of the carrier sense start timing acquired by the carrier sense start timing acquisition unit 15, the transmission power of the radio wave transmitted to the multiplexed mobile station device 30 is limited. For example, it is preferable to interrupt transmission or reduce transmission power. If possible, the null point of the radio wave transmitted to the multiplexed mobile station device 30 may be directed in the direction in which the multiplexing mobile station device 30 exists. The transmission weight control unit 16 realizes the communication restriction by controlling the transmission weight.

  The transmission weight control unit 16 cancels the communication restriction when the multiplexing-side mobile station device 30 completes the carrier sense. Specifically, when the mobile station apparatus response time stored in the carrier sense information table has elapsed from the timing at which the link channel assignment is transmitted, the communication restriction is released. The restriction on communication may be canceled upon reception of the synchronization burst.

  The processing of each unit described above will be described again in more detail with reference to the processing sequence of the mobile communication system 1 and the processing flow of the base station apparatus 10.

  FIG. 4 is a diagram showing a processing sequence of the mobile communication system 1. The time axis is shown on the left side of the figure.

  In the initial state, the base station apparatus 10 and the multiplexed-side mobile station apparatus 30 communicate using a specific link channel (S1). When the multiplex-side mobile station device 30 transmits a link channel establishment request (S2), the base station device 10 determines a multiplex partner (S3). Here, the multiplexed mobile station device 30 is determined as a multiplexing partner.

  When the multiplexing partner is determined, the base station apparatus 10 transmits a link channel assignment indicating a link channel used for communication with the multiplexed mobile station apparatus 30 to the multiplexing mobile station apparatus 30 (S4). Hereinafter, this transmission time is referred to as link channel allocation transmission time (A).

  The multiplex-side mobile station device 30 that has received the link channel assignment starts carrier sense after a lapse of a predetermined time that differs for each mobile station device 30 (S6). Hereinafter, this predetermined time is referred to as carrier sense start required time (C). In the present embodiment, the base station apparatus 10 controls transmission weights (communication restriction) for the multiplexed mobile station apparatus 30 at the timing when the multiplexing mobile station apparatus 30 starts carrier sense (carrier sense start timing). Is started (S5).

  When the carrier sense is completed, the multiplex side mobile station device 30 transmits a synchronization burst (S7). When the synchronization burst is received, the base station apparatus 10 ends the control of the transmission weight and acquires the reception timing as the carrier sense end timing. Hereinafter, the reception time of the synchronization burst is referred to as synchronization burst reception time (B), and the elapsed time from the link channel assignment transmission time (A) to the synchronization burst reception time (B) is referred to as mobile station apparatus response time (D). To do.

  When the transmission weight control is completed, the base station apparatus 10 returns a synchronization burst (S8). Thereby, communication is started between the multiplex side mobile station apparatus 30 and the base station apparatus 10. On the other hand, the communication performed between the multiplexed-side mobile station device 30 and the base station device 10 returns to the normal state (S9). Thereafter, these communications are space division multiplexed.

  FIG. 5 is a diagram illustrating a processing flow of processing (carrier sense information acquisition processing) for the base station apparatus 10 to acquire carrier sense information. As shown in the figure, the base station apparatus 10 first transmits a link channel assignment and acquires a link channel assignment transmission time (A) (S100).

  When the link channel assignment is transmitted, the base station apparatus 10 waits for reception of a synchronization burst. If the carrier sense fails, the mobile station device 30 does not transmit a synchronization burst. In this case, the base station device 10 detects a carrier sense failure due to a reception timeout, and ends the process (negative determination in S101).

  When the synchronization burst is received (Yes in S101), the base station apparatus 10 acquires the synchronization burst reception time (B) and the mobile station apparatus identification information (P) of the multiplex side mobile station apparatus 30 ( S102). Then, a value obtained by subtracting (A) from (B) is obtained as a mobile station apparatus response time (D) (S103), and further, from (D), a predetermined carrier sense time (carrier sense in mobile station apparatus 30) is obtained. A value obtained by subtracting the time required for execution and the time required for transmitting the synchronization burst after completion of carrier sense is acquired as the carrier sense start required time (C) (S104).

  The base station apparatus 10 associates the mobile station apparatus response time (D) and the carrier sense start required time (C) calculated as described above with the mobile station apparatus identification information (P), and generates a carrier sense information table. (S105).

  FIG. 6 is a diagram illustrating a processing flow of processing (transmission weight control processing) for the base station apparatus 10 to perform transmission weight control. As shown in the figure, the base station apparatus 10 first transmits a link channel assignment to the multiplexing-side mobile station apparatus 30 and acquires a link channel assignment transmission time (A) (S200).

  When the link channel assignment is transmitted, the base station device 10 determines whether or not carrier sense information is stored in the carrier sense information table in association with the mobile station device identification information (P) of the multiplexing-side mobile station device 30. (S201). If stored, the carrier sense start timing is acquired from the link channel assignment transmission time (A) and the stored carrier sense start required time (C), and the link channel assignment transmission time (A) and the mobile station apparatus The carrier sense end timing is acquired from the response time (D) (S202). Then, transmission weight control of the multiplexed mobile station device 30 is started from the time indicated by the carrier sense start timing (S203), and is ended at the time indicated by the carrier sense end timing (S204).

  On the other hand, if it is determined in S201 that it is not stored, the base station apparatus 10 acquires the timing corresponding to the link channel allocation transmission time (A) as the carrier sense start timing (S205). Then, transmission weight control of the multiplexed mobile station device 30 is started from the time indicated by the carrier sense start timing (S206), and ends when a synchronization burst is received from the multiplexed mobile station device 30 (S207).

  As described above, according to the mobile communication system 1, the base station apparatus 10 can start limiting communication of the multiplexed mobile station apparatus 30 at the timing when the multiplexing mobile station apparatus 30 starts carrier sense. .

  Moreover, the base station apparatus 10 can acquire carrier sense start timing based on the past performance.

  Furthermore, when the carrier sense start required time (C) is not yet stored, the base station apparatus 10 can set the timing corresponding to the timing at which the link channel assignment is transmitted as the carrier sense start timing.

It is a figure which shows the system configuration | structure of the mobile communication system concerning embodiment of this invention. It is a figure which shows the functional block of the base station apparatus concerning embodiment of this invention. It is a figure which shows the carrier sense information storage table concerning embodiment of this invention. It is a figure for demonstrating the processing sequence of the base station apparatus concerning embodiment of this invention, and explaining each time and each timing. It is a figure which shows the processing flow of the base station apparatus concerning embodiment of this invention. It is a figure which shows the processing flow of the base station apparatus concerning embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Mobile communication system, 10 Base station apparatus, 11 Demodulation part, 12 Link channel establishment request | requirement receiving part, 13 Link channel allocation transmission part, 14 Modulation part, 15 Carrier sense start timing acquisition part, 16 Transmission weight control part, 17 link Channel allocation transmission time acquisition unit, 18 carrier sense start required time acquisition unit, 19 synchronization burst reception unit, 20 synchronization burst reception time acquisition unit, 21 storage unit, 22 antenna, 30 mobile station apparatus.

Claims (3)

Instruction signal transmitting means for transmitting an instruction signal for instructing carrier sense of a specific link channel to the first mobile station apparatus communicating with the base station apparatus;
Carrier sense start timing acquisition means for acquiring a carrier sense start timing indicating a timing at which the first mobile station apparatus starts carrier sense in response to the instruction signal;
Communication restriction for starting restriction of communication at the timing corresponding to the carrier sense start timing acquired by the carrier sense start timing acquisition unit for the second mobile station apparatus communicating on the link channel specified by the instruction signal Starting means;
Communication restriction releasing means for releasing the restriction of communication started by the communication restriction starting means when the first mobile station device completes carrier sense;
Based on the timing at which the instruction signal is transmitted to the first mobile station apparatus by the instruction signal transmission means and the timing at which a predetermined signal indicating completion of carrier sense is received from the first mobile station apparatus Carrier sense start required time acquisition means for acquiring a carrier sense start required time indicating a time required for the first mobile station apparatus to start carrier sense after transmission of the instruction signal by the instruction signal transmission means;
Storage means for storing information indicating the first mobile station device and carrier sense start required time acquired by the carrier sense start required time acquisition means in association with each other;
Only including,
When the carrier sense start timing acquisition unit stores the carrier sense start required time in association with the information indicating the first mobile station apparatus by the storage unit, the carrier sense start required time and the instruction signal The carrier sense start timing is acquired based on the timing at which the instruction signal is transmitted by a transmission unit.
The base station apparatus according to claim and this. The base station apparatus according to claim 1,
The carrier sense start timing acquisition means receives the instruction signal by the instruction signal transmission means when the storage means does not store a carrier sense start required time in association with information indicating the first mobile station apparatus. Obtaining a timing corresponding to the transmitted timing as the carrier sense start timing;
A base station apparatus. An instruction signal transmission step of transmitting an instruction signal for instructing carrier sense of a specific link channel from the base station apparatus to the first mobile station apparatus communicating with the base station apparatus;
A carrier sense start timing acquisition step of acquiring a carrier sense start timing indicating a timing at which the first mobile station apparatus starts carrier sense in response to the instruction signal;
Communication restriction for starting restriction of communication at the timing corresponding to the carrier sense start timing acquired in the carrier sense start timing acquisition step for the second mobile station apparatus communicating on the link channel specified by the instruction signal A starting step;
A communication restriction release step for releasing the restriction of communication started by the communication restriction start step when the first mobile station apparatus completes carrier sense;
Based on the timing at which the instruction signal is transmitted to the first mobile station apparatus in the instruction signal transmission step and the timing at which a predetermined signal indicating completion of carrier sense is received from the first mobile station apparatus A carrier sense start required time acquisition step for acquiring a carrier sense start required time indicating a time required for the first mobile station apparatus to start carrier sense after transmission of the instruction signal in the instruction signal transmission step;
A storage step of associating the information indicating the first mobile station apparatus with the carrier sense start required time acquired in the carrier sense start required time acquisition step in association with the storage means;
Including
In the carrier sense start timing acquisition step, when the storage means stores a carrier sense start required time in association with information indicating the first mobile station apparatus, the carrier sense start required time and the instruction signal Acquiring the carrier sense start timing based on the timing at which the instruction signal is transmitted in the transmission step;
A communication restriction method.

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