JP2012074843A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system having means for preventing the failure of communication due to the simultaneous call connection of multiple mobile stations.SOLUTION: A radio communication system includes: a base station; multiple mobile stations; and a relay base station having a function of relaying radio communication between the base station and the mobile stations. When a communication request signal to the base station is received from one of the multiple mobile stations, the relay base station transmits to the multiple mobile stations, a response wait signal for announcing the presence of the mobile station waiting a response from the base station.

Description

  The present invention relates to interference prevention when a call connection from a mobile station to a base station is made via a relay base station in a radio communication system including a base station, a relay base station, and a plurality of mobile stations.

  One digital wireless access system for fire fighting and emergency services is the SCPC (Single Channel Per Carrier) system. This SCPC system is a system that allocates one communication (one channel) per carrier wave, and is a system that can be expected to operate in the same manner as the current analog system fire fighting / emergency radio.

  An example of a system configuration employing this SCPC method will be described with reference to FIG. In FIG. 1, a console 21 is a device for directing the entire wireless system to communicate with a mobile station. The control device 22 is a device for realizing functions such as an interface to the console 21 in addition to the connection control of the base station 10. The base station 10 includes a transmission / reception device for communicating with the mobile station 12 in the jurisdiction area, and is connected to the console 21 via a control device 22 in a wired manner. The mobile station 12 directly communicates with the mobile station 12 in the service area of the base station 10, but in the case of communication with the mobile station 13 or 14 outside the service area, the relay base station 11 communicates with the mobile station 13 or 14. Relay. Since the relay base station 11 needs to relay communication between the base station 10 and the mobile station 13 or 14, the relay base station 11 has a transmission / reception device for communicating with each other at different frequencies.

  In FIG. 1, FHn (n = 1, 2) represents the downlink frequency from the base station 10 and the relay base station 11, and FLn (n = 1, 2) represents the relay base station 11, the mobile station. The uplink frequency from 12 to 14 is represented. Also, broadcast information (empty line) is periodically transmitted from the base station 10 at the frequency FH1. The broadcast information is a signal for notifying various information such as a switching determination level for automatically switching the reception channel in the mobile stations 12 to 14, and this broadcast information is also relayed by the relay base station 11 to be transmitted to the mobile station 13. And 14 are notified.

For example, Patent Literature 1 has already been proposed as a wireless communication system in which a base station and a mobile station communicate via such a relay base station. In this patent document 1, when a radio base station and a radio terminal communicate via a radio relay station, the radio base station (the occurrence of a time lag) is considered in consideration of the time required for relay processing in the radio relay station (occurrence of time lag). (Or a radio relay station) and a message or data managed by the radio terminal can be adjusted so that the reception or transmission timing of the message or data coincides with each other, so that the message or data can be received correctly at the scheduled timing in the radio terminal or radio base station. The purpose is to do so.
JP 2008-109374 A

  An example of a communication method used in a radio communication system including a base station, a relay base station, and a plurality of mobile stations is RICH (Radio Information Channel). FIG. 2 is a schematic diagram showing the format of RICH communication. As shown in FIG. 2, the RICH communication is transmitted and received with three octets as one unit. Of the RICH communication format, S is protocol identification information, and is used to indicate whether it is user information or RICH using 2 bits. F is radio channel structure identification information, and is used to indicate tracking or non-tracking of the base station in communication or synchronization burst using 3 bits. M is communication mode identification information, and is used to indicate the type of communication being transmitted / received using 3 bits, such as voice data, non-voice data, and a blank line. D is operation mode identification information, and is used to indicate the state of the communication line such as idle or connected using 3 bits. CC is a color code and is used to indicate a communication type such as simultaneous transmission, group transmission, and individual communication using 6 bits.

  A TCH (Traffic Channel) is a channel in the communication mode identification information M for transferring user information (voice / non-voice data). SB0 (Synchronous Burst 0: Synchronous Burst 0) is burst data in the radio channel structure identification information F and exchanged before transferring user information.

Here, in the wireless communication system shown in FIG. 1, a communication sequence when a communication request is made from the mobile station 13 located in the area of the relay base station 11 to the base station 10 will be described in detail based on FIG. 5. explain. As a communication method, the above-described RICH communication is used.
First, “empty line, RI (D = idle)” indicating that the communication channel (air) is unused is transmitted from the base station 10, and the relay base station 11 relays this to the relay base station area. Transmit to mobile stations 13 and 14 inside. The mobile stations 13 and 14 that have received this empty line recognize that communication with the base station 10 is possible.

  Here, when the mobile station 13 presses on and tries to perform voice communication with the base station 10, first, “SB 0: communication request, RI (D = simultaneous)” is transmitted from the mobile station 13. At this time, a calling number and a calling ID for specifying the mobile station 13 are also transmitted at the same time. The relay base station 11 that has received this transmits the received signal to the base station 10 as it is after switching to the transmission frequency. Receiving this, the base station 10 notifies the console 21 that the incoming call has been turned on, and “SB0: communication response, RI (D = BUSY)” is transmitted. At this time, a calling number and a calling ID for specifying the mobile station 13 that has acquired the transmission right are also transmitted at the same time. The relay base station 11 that has received the communication response signal transmitted by the base station 10 transmits the received signal to the mobile station 13 and the mobile station 14 after switching the transmission frequency. The mobile station 13 acquires the transmission right by receiving the signal, and the mobile station 14 determines that the communication channel (air) is in use by receiving the signal and sets the lock / interrupt disabled.

  The mobile station 13 starts transmission after acquiring the transmission right. Specifically, “TCH: voice, RI (D = simultaneous)” is transmitted, and a voice signal is sent to the console 21 via the relay base station 11 and the base station 10. Further, the base station 10 transmits “TCH: voice, RI (D = BUSY)” at the timing when “TCH: voice, RI (D = simultaneous)” is received, so that the mobile station other than the mobile station 13 can transmit it. In addition, it notifies that voice communication is ongoing.

  When the mobile station 13 presses off and tries to end the voice communication with the base station 10, "TCH: idle, RI (D = simultaneous)" is transmitted. The base station 10 that has received the signal via the relay base station 11 transmits a return “TCH: Idle, RI (D = BUSY)” to the other mobile stations that communication is still impossible. Notice. Thereafter, the mobile station 10 notifies the console 21 that the incoming call has been turned off, and further transmits “TCH: idle, RI (D = simultaneous)” to all the mobile stations 12 to 14. Then, it is notified that communication is possible and the lock is released.

  Here, when the communication request signal is transmitted after being pressed on in the mobile station 13, the communication request signal is composed of, for example, 40 ms, so 40 ms between the mobile station 13 and the relay base station 11 It takes 40 ms from the station 11 to the base station 10 and requires 80 ms one way. Further, for example, 120 ms is required as a processing delay time (time lag) from when the base station 10 receives the communication request signal to when it transmits the communication response signal. When the processing delay time in the relay base station 12 is considered as + α, it takes 80 ms + 120 ms + 80 ms + α, that is, 280 ms + α until the mobile station 14 recognizes that the communication channel is in use after the mobile station 13 is pressed ON. It will be. If the mobile station 14 is pressed on during this time, there is a problem that the communication is disturbed and the communication fails.

  Also, since the mobile station does not have a means for determining whether the communication area being served is under the control of the base station or the relay base station, the number of times the uplink signal is sent for call connection includes the host device in advance. However, it has to be a long fixed number of times taking into account the delay time of the network. By setting the number of times of transmission to be longer, it is possible to establish a reliable connection, but on the other hand, if it is under the control of the base station, it becomes an extra number of signal transmission times and it takes time to connect. Although it is possible to shorten the number of signal transmissions and perform parting-off, there is a problem that the possibility of problems such as connection failure and talk head interruption increases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a wireless communication system having means for preventing a plurality of mobile stations from making a call connection at the same time and failing in communication. It is what.

  Claim 1 of the present invention is a wireless communication system comprising a base station, a plurality of mobile stations, and a relay base station having a function of relaying wireless communication between the base station and the mobile station, When the relay base station receives a communication request signal from one of the plurality of mobile stations to the base station, the relay base station notifies that there is a mobile station waiting for a response from the base station. A wireless communication system characterized by transmitting a waiting signal toward the plurality of mobile stations.

  According to claim 2 of the present invention, in addition to claim 1, a mobile station that has not transmitted the communication request signal among the plurality of mobile stations that have received the response waiting signal does not transmit a new communication request signal This is a wireless communication system.

  According to claim 3 of the present invention, in addition to claim 1, the relay base station transmits a signal transmitted from the mobile station until communication between the base station and the mobile station is canceled. The wireless communication system is characterized in that the response waiting signal is transmitted to the plurality of mobile stations each time it is received.

  According to a fourth aspect of the present invention, in addition to the first aspect, when the mobile station transmits the communication request signal, the mobile station includes carrier sensing means for confirming whether another mobile station is transmitting. This is a wireless communication system.

  According to the first aspect of the present invention, when the relay base station receives a communication request signal from one of the plurality of mobile stations to the base station, the relay base station waits for a response from the base station. Since a response waiting signal notifying that there is a station is transmitted to the plurality of mobile stations, other mobile stations misunderstand that communication is possible even though communication is actually impossible. Therefore, it is possible to prevent a communication failure due to an interruption by another mobile station, and to maintain high communication reliability.

  According to the second aspect of the present invention, a mobile station that has not transmitted the communication request signal among a plurality of mobile stations that have received a response waiting signal does not transmit a new communication request signal, thereby Can prevent interruption.

  According to the third aspect of the present invention, the relay base station waits for the response each time it receives a signal transmitted from the mobile station until communication between the base station and the mobile station is canceled. Since the signal is transmitted to the plurality of mobile stations, an opportunity for recognizing that a mobile station that has moved from the middle to the relay base station area cannot communicate is increased, The time can be shortened, and it is possible to prevent a mobile station that has moved into the relay base station area from being interrupted from interrupting communication.

  According to the invention of claim 4, when the mobile station transmits the communication request signal, the mobile station is provided with carrier sensing means for confirming whether another mobile station is transmitting, so that the relay station can There is a time lag until another mobile station to be transmitted receives a signal waiting for a response, and interruption can be completely prevented by setting the time corresponding to the time lag as the carrier sensing time.

It is the schematic diagram showing the positional relationship of the base station, relay base station, and mobile station which comprise a radio | wireless communications system. It is a schematic diagram showing the format of RICH communication. It is a communication sequence diagram in the radio | wireless communications system of this invention. It is a block diagram showing the simple structure of the radio | wireless apparatus of (a) base station, (b) relay base station, and (c) mobile station which comprise a radio | wireless system. It is a communication sequence diagram in the conventional radio | wireless communications system.

  A radio communication system according to the present invention is a radio communication system comprising a base station, a plurality of mobile stations, and a relay base station having a function of relaying radio communication between the base station and the mobile station, When the relay base station receives a communication request signal from one of the plurality of mobile stations to the base station, the relay base station notifies that there is a mobile station waiting for a response from the base station. A waiting signal is transmitted to the plurality of mobile stations. Details will be described below.

  An embodiment of a wireless communication system according to the present invention will be described with reference to the drawings. The configuration of the entire system is the same as that shown in FIG. 1, and includes a console 21, a control device 22, a base station 10, a relay base station 11, and mobile stations 12 to 14. Although the relay base station 11 is a fixed station, the present invention can be similarly applied to a movable relay device such as an in-vehicle relay station.

  Next, wireless devices in each system component will be described. FIG. 4 (a) is a block diagram showing a radio apparatus of the base station 10, and includes a transmission unit 15a, a reception unit 16a, a modulation / demodulation processing unit 17a, a control unit 18a, a storage unit 19a, and data / voice. It is comprised by the process part 20a. For example, when the communication request signal from the mobile station 14 is received by the receiving unit 16a, the modulation / demodulation processing unit 17a demodulates and processes the communication request by the control unit 18a, and the control device via the data / voice processing unit 20a 22, the console 21 is notified of incoming calls from the mobile stations 12 to 14, and the control unit 18 generates communication response signals for the mobile stations 12 to 14 and transmits them via the modulation / demodulation processing unit 17a. It transmits from the part 15a.

  FIG. 4B is a block diagram showing a radio apparatus of the relay base station 11, and includes a transmission unit 15b, a reception unit 16b, a modulation / demodulation processing unit 17b, a control unit 18b, a storage unit 19b, Two sets of transmission / reception unit configured by the audio processing unit 20b, and transmission / reception unit configured by the transmission unit 15c, the reception unit 16c, the modulation / demodulation processing unit 17c, the control unit 18c, the storage unit 19c, and the data / audio processing unit 20c It is comprised by the transmission / reception part. For example, when the communication request signal from the mobile station 13 is relayed to the base station 10, the communication request signal is received by the receiving unit 16c, and the communication request is sent from the data / voice processing unit 20c to the data / voice processing unit 20b. The data of the signal is transmitted, and the data of the communication request signal received by the data voice processing unit 20b is transmitted from the transmission unit 15b to the base station 10.

  FIG. 4 (c) is a block diagram showing radio apparatuses of the mobile stations 12 to 14, including a transmission unit 15d, a reception unit 16d, a modulation / demodulation processing unit 17d, a control unit 18d, a storage unit 19d, and data -It is comprised by the audio | voice processing part 20d. For example, the receiving unit 16d receives and demodulates broadcast information (empty line) from the base station 10 at the frequency FH1, acquires the switching determination level, stores it in the storage unit 19d, and then receives the signal received by the receiving unit 16d. The control unit 18d compares the level with a switching determination level that is a determination threshold for determining whether or not to perform a level search for receiving channel setting, and determines whether or not the level is equal to or higher than the switching determination level. If it is below the switching determination level, it means that it has moved out of the communication service area, and a level search for newly setting the reception frequency FH2 is performed.

  The present invention is the same as the conventional system configuration, but the processing in the relay base station 11 when a communication request (press ON) is received from a mobile station in the relay base station area is different from the conventional one. There will be described below based on the communication sequence diagram of FIG.

  In FIG. 3, first, “empty line, RI (D = idle)” indicating that the communication channel is unused is transmitted from the base station 10, and the relay base station 11 relays this to the relay base station. Transmit to mobile stations 13 and 14 in the area. The mobile stations 13 and 14 that have received this empty line recognize that communication with the base station 10 is possible.

  Here, when the mobile station 13 presses on and tries to perform voice communication with the base station 10, first, “SB 0: communication request, RI (D = simultaneous)” is transmitted from the mobile station 13. At this time, a calling number and a calling ID for specifying the mobile station 13 are also transmitted at the same time. The relay base station 11 that has received this signal waits for a response to notify the mobile stations in the relay base station area (mobile stations 13 and 14 in the case of FIG. 1) that the mobile station 13 is in a response wait state. Then, it sends back “TCH: Idle, RI (D = BUSY (waiting for response))”. Here, “TCH: idle, RI (D = BUSY (waiting for response))” transmitted from the relay base station 11 is a new operation mode identification information D in the RICH (radio information channel) as shown in FIG. "011: BUSY (waiting for response)" defined as one of the above, and notifies the mobile station 13 that has performed the press-on that the service area in the area is under the relay base station. The mobile station 14 having a function and not transmitting a communication request in the relay base station area has a function of notifying that the communication channel is in use.

  After that, the relay base station 11 that has received “SB0: communication request, RI (D = simultaneous)” from the mobile station 13 switches the received signal to the transmission frequency and transmits it to the base station 10 as it is. Receiving this, the base station 10 notifies the console 21 that the incoming call has been turned on, and “SB0: communication response, RI (D = BUSY)” is transmitted. At this time, a calling number and a calling ID for specifying the mobile station 13 that has acquired the transmission right are also transmitted at the same time. The relay base station 11 that has received the communication response signal transmitted by the base station 10 transmits the received signal to the mobile station 13 and the mobile station 14 after switching the transmission frequency. The mobile station 13 acquires the transmission right by receiving the signal, and the mobile station 14 determines that the communication channel is still in use by receiving the signal and sets the lock to continue.

  The mobile station 13 starts transmission after acquiring the transmission right. Specifically, “TCH: voice, RI (D = simultaneous)” is transmitted. The relay base station 11 that has received “TCH: voice, RI (D = simultaneous)” transmits a loopback “TCH: idle, RI (D = BUSY (waiting for response))” and also sends “ “TCH: voice, RI (D = simultaneous)” is transmitted, and as a result, a voice signal is sent to the console 21. Further, the base station 10 transmits “TCH: voice, RI (D = BUSY)” at the timing when “TCH: voice, RI (D = simultaneous)” is received, so that the mobile station other than the mobile station 13 can transmit it. In addition, it notifies that voice communication is ongoing.

  When the mobile station 13 presses off and tries to end the voice communication with the base station 10, "TCH: idle, RI (D = simultaneous)" is transmitted. The relay base station 11 that has received “TCH: Idle, RI (D = simultaneous)” sends back “TCH: Idle, RI (D = BUSY (waiting for response))”. The base station 10 that has received “TCH: idle, RI (D = simultaneous)” via the relay base station 11 transmits a return “TCH: idle, RI (D = BUSY)” and is still in a state where communication is not possible. Notify other mobile stations that there is. Thereafter, the mobile station 10 notifies the console 21 that the incoming call has been turned off, and further transmits “TCH: idle, RI (D = simultaneous)” to all the mobile stations 12 to 14. Then, it is notified that communication is possible and the lock is released.

Note that “TCH: idle, RI (D = BUSY (waiting for response))” is newly defined as one of the operation mode identifications in the RICH (radio information channel) in the conventional operation mode, for example, Because there was a problem.
<Folding of “SB0” signal>
The return of the SB0 signal with “BUSY” is effective in terms of rejecting other mobile stations, but indicates “acquired transmission right” to the requesting mobile station and means completion of the call connection with the host device. Therefore, the SB0 signal is not properly folded.
<Transmission of “TCH: idle” signal>
The “TCH: idle” signal with “BUSY” means the end of the call by itself, and communication including the requesting mobile station is not established, so that transmission of this signal is not appropriate.
<Transmission of “TCH: Idle, D = BUSY (Connecting)” Signal>
This signal is not appropriate because it includes the meaning of giving a transmission right to the called station in select call communication or the like.

  As described above, the feature of the radio communication system according to the present invention is that when the relay base station 11 receives a communication request signal (press ON) from the mobile station, the return “TCH: idle, RI (D = BUSY) (Waiting for response)) ”is transmitted.

  That is, in the conventional relay base station 11, the relay base station performs through relay that performs only the operation of relaying the signal received from the mobile station or the base station as it is without processing it. It was at the stage of receiving a signal from the base station that other mobile stations in the network could recognize that the communication channel was in use. Therefore, as described in the prior art, for example, it took 280 ms + α to recognize that the mobile station 14 is in the communication channel use state from the press-on of the mobile station 13 in FIG. However, as in the present invention, when the relay base station 11 receives a press ON or the like, it sends back “TCH: Idle, RI (D = BUSY (waiting for response))”, so that 40 ms + 40 ms = The mobile station 14 can recognize that the communication channel is being used in 80 ms, and compares the period when other mobile stations misunderstand that communication is possible even though communication is actually impossible. And can be shortened. This makes it possible to prevent a communication failure due to another mobile station interrupting, and to maintain high communication reliability.

  Further, when a signal is transmitted from the mobile station 13 that is using the communication channel to the relay base station 11 not only when the press is ON but also when transmitting or when the press is OFF, the return is always “TCH: idle”. , RI (D = BUSY (waiting for response)) ”, it can be said that the opportunity for other mobile stations to recognize that communication is impossible has increased. Therefore, for example, an opportunity for recognizing that a mobile station that has moved into the relay base station area from the middle is incapable of communication is increased, and the time until recognition can be shortened. It is possible to prevent a mobile station that has moved into the area from interrupting communication.

  In addition, since the mobile station 13 that has received the request “TCH: Idle, RI (D = BUSY (response waiting))” can recognize that it is under the control of the relay base station, the number of signal transmissions It is possible to avoid problems such as connection failure and talk head interruption.

  Furthermore, when a mobile station transmits a communication request signal, it is transmitted from a relay station by providing a carrier sensing function that once watches a transmission channel in order to check whether another mobile station is transmitting. There is a time lag until another mobile station receives a signal waiting for a response, and interruption can be completely prevented by setting the time for the time lag as the carrier sensing time.

DESCRIPTION OF SYMBOLS 10 ... Base station, 11 ... Relay base station, 12 ... Mobile station, 13 ... Mobile station, 14 ... Mobile station, 15a-15d ... Transmitter, 16a-16d ... Receiver, 17a-17d ... Modulation / demodulation processor, 18a- 18d: control unit, 19a-19d ... storage unit, 20a-20d ... data / sound processing unit, 21 ... console, 22 ... control device.

Claims (4)

A wireless communication system comprising a base station, a plurality of mobile stations, and a relay base station having a function of relaying wireless communication between the base station and the mobile station,
When the relay base station receives a communication request signal from one of the plurality of mobile stations to the base station, the relay base station notifies that there is a mobile station waiting for a response from the base station. A wireless communication system, wherein a response waiting signal is transmitted to the plurality of mobile stations.   2. The wireless communication system according to claim 1, wherein a mobile station that has not transmitted the communication request signal among the plurality of mobile stations that have received the response waiting signal does not transmit a new communication request signal.   The relay base station sends the response waiting signal to the plurality of mobile stations each time it receives a signal transmitted from the mobile station until communication between the base station and the mobile station is canceled. The wireless communication system according to claim 1, wherein the wireless communication system transmits the packet toward the destination.   The wireless communication system according to claim 1, wherein the mobile station is provided with carrier sensing means for confirming whether another mobile station is transmitting when transmitting the communication request signal.

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