JP3978431B2 - Digital radio system and digital radio communication method - Google Patents

Description

  The present invention relates to a digital radio system and a digital radio communication method, and more particularly, to a digital radio communication system using a press talk and a communication control of the digital radio communication method.

  As shown in FIG. 8, a digital radio communication system currently in practical use includes a base station radio 801 (hereinafter abbreviated as a base station 801) and a plurality of mobile station radios within a communication area 802 of the base station 801. M1, M2,... Mn (where a mobile station radio is abbreviated as a mobile station, and when a mobile station is generically referred to as a mobile station M), there is a communication connection service. A system configured to be performed.

  In FIG. 8, the base station 801 is assigned with uplink and downlink radio frequencies in pairs, and the transmission wave transmitted from the base station 801 is transmitted to the downlink F1, and, for example, from the mobile station M1 to the base station 801. The transmitted wave is referred to as upstream wave f1. Communication between the base station 801 and the mobile station M is performed using these uplink and downlink pair waves. The communication area 802 is an operation area of the base station 801. Such a system is one of SCPC (Single Channel Per Carrier) frequency division multiple access (FDMA), and is a method of allocating one carrier per voice channel.

  Thus, FIG. 9 shows radio carrier frequency allocation that is permitted to be used in, for example, a narrowband digital system including a regional disaster prevention system using digital radio technology in Japan. In FIG. 9, 160 waves (f1, f2,...) Are recognized in the 4 MHz band with a width of 25 KHz on the basis of 262 MHz in the uplink direction, that is, the direction from the mobile station to the base station. In the downstream direction, that is, in the direction from the control station to the mobile station, 160 waves (F1, F2,...) Are recognized with a 25 MHz width in the 4 MHz band with reference to 271 MHz 9 MHz away from 262 MHz in the upstream direction. It has been. Therefore, in the communication of the digital wireless communication system, any one of the frequencies in the upstream direction f1, f2,..., The downstream direction F1, F2,. Each system can use one or a plurality of radio carriers as control carriers and the rest as communication carriers according to the scale. The standard for digital radio systems in Japan is stipulated in ARIB (Association of Radio Industries and Businesses) Standard T61 (Publisher Association of Radio Industries Association) (hereinafter referred to as ARIB STD T61).

  In the example shown in FIG. 8, the mobile station M1 is in a transmission state due to a press talk, and the information transmitted from the mobile station M1 is the mobile station M2 in the other reception state in the base zone via the base station 801. , M3,..., Mn, and the base station 801 receives the upstream wave f1 from the mobile station M1, and transmits the received signal by replacing it with the downstream wave F1. Therefore, it is not possible to make a call from the mobile stations M2, M3,.

  Further, ARIB STD T61 defines the frame format and connection procedure of data used in such a system. This is a communication system in which a base station or a mobile station makes a call according to a connection procedure according to the standard by Press Talk, and the other station only performs reception and can make a call after the other party's call is completed. is there.

  Further, a group communication device (see, for example, Patent Document 1) discloses a method in which another mobile station performs emergency communication when a mobile station to which a transmission right is granted is communicating. That is, it is shown that a mobile station that performs emergency communication uses a control channel when it is in the same radio zone as a mobile station that is transmitting, and uses a communication channel when it is in a different radio zone.

JP 2000-350256 A

  In the above-described PressTalk digital wireless communication system, if a mobile station that is in a transmission state by PressTalk is within the same communication area among mobile stations that use the same system, other mobile stations cannot communicate, It is occupied by one mobile station. Therefore, after the transmission of the occupied mobile station is completed, the other mobile stations can only communicate. In addition, even if transmission by press talk is performed in a state not intended by the operator of the mobile station, the transmission state cannot be stopped. Furthermore, when an event that requires emergency communication occurs in the system, if the station in the transmission state is a base station, it is possible to stop transmission. There is a problem that it is difficult to respond to the event immediately.

  An object of the present invention is to provide a digital radio system and a digital radio communication method capable of releasing a communication channel dedicated by broadcast information from a base station.

  Another object of the present invention is to provide a digital radio system and a digital radio communication method for periodically monitoring broadcast information from a base station by a mobile station.

  Still another object of the present invention is to provide a digital radio system and a digital radio communication method that can reliably cope with an emergency.

The present invention provides a digital radio system having a base station and a plurality of mobile stations, and performing communication between the base station and the plurality of mobile stations, wherein the base station is one of the plurality of mobile stations. When communicating with one mobile station using a plurality of continuous uplink voice frames and downlink voice frames including broadcast information, the base station transmits a predetermined downlink voice frame among the plurality of consecutive downlink voice frames. Means for inserting transmission stop information of the mobile station, and the mobile station stops transmission of the own station based on the means for detecting the transmission stop information from the plurality of downlink voice frames and the transmission stop information; Configured to have means.

  In the digital radio system of the present invention, the base station is configured to continuously insert the transmission stop information into at least two frames of the downlink voice frame.

  In the digital radio system of the present invention, the base station inserts the transmission stop information into a radio information channel of the downlink voice frame.

  Further, in the digital radio system of the present invention, the means for detecting the transmission stop information from the downlink voice frame of the mobile station has a function of detecting every plural frames of the downlink voice frame from the base station. Configured.

Furthermore, the present invention includes a base station and a plurality of mobile stations, the mobile station Oite the digital radio system which performs communication, the base station of the plurality of between the base station and a plurality of the mobile station When communicating with one of the mobile stations using a plurality of consecutive uplink voice frames including a plurality of broadcast information and a plurality of downlink voice frames, the base station determines a predetermined one of the plurality of consecutive downlink voice frames. The transmission stop information of the mobile station is inserted into the downlink voice frame of the mobile station, and the mobile station detects the transmission stop information from the plurality of downlink voice frames and stops transmission of the own station based on the transmission stop information. Configured as follows.

Further, in an SCPC digital radio system having a base station and a plurality of mobile stations and performing communication between the base station and the plurality of mobile stations, the base station is included in the plurality of mobile stations. When communicating with one mobile station using a plurality of consecutive uplink voice frames and a plurality of downlink voice frames including broadcast information, the base station transmits a predetermined plurality of the plurality of consecutive downlink voice frames. The transmission stop information of the mobile station performing the communication is inserted into the downlink voice frame, and the predetermined number of frames n of the plurality of downlink voice frames is set in the mobile station performing the communication, and the predetermined number of frames n or less. If so, the mobile station is configured to continue transmission processing, perform detection processing of the transmission stop information every nth predetermined frame, and stop transmission of the mobile station based on the transmission stop information. The

  In the digital wireless communication method of the present invention, the mobile station is configured to continue transmission to the base station using the uplink voice frame when it does not detect transmission stop information from the base station.

  As described above, according to the present invention, when the base station detects an event that the base station wishes to perform emergency communication in the system while the mobile station is transmitting, the mobile station can stop transmission and perform emergency communication. In addition, it is possible to confirm broadcast information by performing reception while the mobile station is transmitting, confirm transmission stop, stop transmission regardless of press talk according to the broadcast stop broadcast information, etc. It is effective as a digital wireless communication system.

  FIG. 1 is a schematic block diagram of a mobile station radio (hereinafter abbreviated as a mobile station M) used in an embodiment of the present invention. In FIG. 1, a communication signal from a base station 801 is received by an antenna 101, subjected to frequency conversion by an RF unit (high frequency unit) 102, subjected to unnecessary component removal and amplification processing, and then applied to a demodulation unit 103. The The demodulating unit 103 converts the data into audio data, the channel codec unit 104 extracts audio data necessary for audio reproduction from a data frame configuration described later, and the extracted audio data is input to the audio codec unit 105. In the audio codec unit 105, the input digital data is decoded into audio, applied to the audio output unit 106, and output as audio from the audio output unit 106. Reference numeral 107 denotes a system control unit composed of a CPU and the like, and controls the operation of each unit of the digital wireless device described above. Reference numeral 108 denotes a key input unit, which is used to input a destination number and various settings. Reference numerals 109 and 110 denote an LED display unit and an LCD display unit that perform various displays for transmission and reception. Reference numeral 111 denotes an audio memory for recording a message. In addition to a semiconductor memory, for example, a volatile memory or a non-volatile memory (EPROM: Erasable Programmable Read-only Memory), a magnetic recording device, for example, a magnetic desk or a magnetic tape Various recording devices such as a magneto-optical (MO) recording device can be used. Reference numeral 112 denotes a vibration motor unit that transmits an incoming important message to a user (or an operator) by vibration. Reference numeral 113 denotes a buzzer unit that informs the user of an incoming important message by sound. In the above description, the demodulation of the received signal from the antenna 101 has been described. However, FIG. 1 also has the function of a transmitter, and the sound from the sound input unit 106 is appropriately processed and transmitted from the antenna 101. Since this is the same as that of a conventional digital wireless device, detailed description is omitted.

  FIG. 2 shows a state where the base station 801 and the mobile station M communicate with each other using the downlink frame DF and the uplink frame UF. This corresponds to the upstream and downstream pair waves F1 and f1 in the ARIB STD T61 standard. The difference between the first symbol of the downlink frame DF from the base station 801 and the first frame of the uplink frame UF is 60 ms, which is called the frame offset time. Therefore, the first symbol of the upstream frame UF is transmitted from the mobile station M 60 ms after the first symbol of the downstream frame DF from the base station 801.

  FIG. 3 illustrates an example of channel information of the uplink and downlink signals f1 and F1 between the base station 801 and the mobile station M that are performing transmission. In FIG. 3, downlink voice frames 301-1,... 301-5 are received by the base station 801 from the transmitting mobile station, for example, the voice channel from the mobile station M1, and the frame is transmitted to the mobile station M side. This is the audio frame seen. Note that the audio frame 301 is collectively referred to as an audio frame. This audio frame 301 indicates that broadcast information is being sent from the mobile station M1 to the mobile station M. On the other hand, uplink voice frames 302-1 and 302-2 indicate voice frames transmitted by the mobile station M1 by press talk. The downlink voice frame 301-4 is a frame in which information is added by the base station 801 to an area representing transmission stop information described later. A frame 303 corresponding to the downlink voice frame 301-4 is assigned by the mobile station M1. The figure shows the position of a downstream frame where transmission is temporarily stopped during transmission.

  Here, for example, a method of adding transmission stop information to the downlink voice frame 301-4 at the base station 801 in an emergency will be described in detail with reference to FIGS. FIG. 4 shows the audio channel signal format (data frame structure) according to the ARIB STD T61 standard. In FIG. 4, LP + R is a portion allocated for the training period of the linearizer and the transient response (ramp up and ramp down) of the burst wave. Hereinafter, such a part is referred to as an information unit. Pa is a preamble and is a signal of one symbol of data “1” and data “0”. TCH is a traffic channel, and voice data is transmitted using this TCH. The RICH is a radio information channel that transmits information for maintaining a radio channel. SW is a sync word. An undefined information unit is an information unit that a user can freely use. The numbers in the information unit represent the number of bits of data.

  The addition of transmission stop information in the present invention uses the RICH information unit of the signal format of the voice channel. FIG. 5 is a diagram for explaining the contents of the RICH used in the present invention in more detail. In FIG. 5, F is a radio channel structure identification area, M is a communication mode identification area, and D is an operation mode identification area. Reference numerals 501 and 502 are undefined areas, and these areas can be freely used by the user. These areas are defined by ARIB STD T61. The area shown in FIG. 5 is composed of 17 bits, which are CRC (Cyclic Redundancy Check) coding, fixed bit insertion, convolutional coding, and interleaving to form a 56-bit radio information channel RICH.

  Therefore, transmission stop information is added to the undefined area 501 or 502. That is, the notification of the information indicating the transmission stop is transmitted using the RICH in the voice frame shown in FIG. FIG. 5 shows the details of the RICH in detail. The undefined areas 501 and 502 of the RICH are areas in which the use of bits is not defined in the ARIB STD T61 standard. Use to display the status. For example, the transmission stop information can be realized by inserting information “11” in the undefined area 501 and no transmission stop, that is, the normal state can be realized by inserting information “00”. This information is not particularly limited to “11” and “00”, but can be defined and used in advance by the system. Therefore, a bit indicating transmission stop may be inserted only when an urgent event occurs. In this embodiment, the undefined areas 501 and 502 are used. However, if there are undefined areas other than these areas, the undefined areas can also be used.

  Next, the operation of the present invention will be described with reference to FIGS. First, FIG. 3 shows a state in which the base station 801 and the mobile station M1 perform a call using the downlink frame 301. And, except for emergency, “00” is always inserted into the undefined area 501 shown in FIG. However, when an emergency occurs, the base station 801 inserts the information “11” indicating the transmission stop information 601 into the undefined area 501 shown in FIG. 5 in the downlink frame 301-4 during a call with the mobile station M1. . When the transmission stop information 601 is inserted, in the mobile station M1, the contents of the RICH are decoded by the channel codec unit 104 described above with reference to FIG. 1, and the decoding result is transmitted to the system control unit 107. The system control unit 107 stops transmission of the mobile station M1 based on the transmission stop information 601 and simultaneously displays emergency information on the LED display unit 109 and the LCD display unit 110, vibrates the vibration motor unit 112, The unit 113 notifies the user. Note that the base station 801 does not insert the transmission stop information 601 in only one frame, but normally inserts it in several frames for the certainty of reception. The transmission stop information 601 can be always detected in synchronization with the arrival of the downstream frame 301. However, the transmission stop information 601 should be detected at a rate of once every several frames due to the load of the processing device and the processing speed. However, the method will be described next.

  FIG. 7 shows an example of determining whether to stop transmission based on the number of frames. First, the frame counter sequentially starts counting the number of downstream frames 301 in accordance with the start of transmission by press talk (step 701). A frame counter (not shown) is provided in the system control unit 107. Step 702 is a transmission stop information detection processing step. For example, when the number of transmitted frames n is set to a predetermined value, for example, n = 4, it is determined whether or not the number of transmitted frames is four. The setting method can be performed by the key input unit 108, for example. If the number of frames has not reached the set value, for example, if it is four times or less, the processing proceeds to transmission processing step 703 and transmission is continued. When the number of frames reaches the set value n = 4, the frame counter is cleared to “0” in the frame counter clear step 704 and the frame counter starts counting the down frame 301 again. This is repeated.

  On the other hand, in the reception processing step 705, the reception processing of the downstream frame 301-4 is performed. In this reception processing step 705, as shown in FIG. 2, since there is an offset of 60 ms at the start of transmission between the base station 801 and the mobile station M1, if reception starts at the transmission start timing of the mobile station M1, the base station 801 However, since the downlink frame 301 from the base station 801 is continuous as shown in FIG. 3, the next frame 301-4 can be received (reception). It is shown at the timing of 303). Note that the data for transmission at this time is discarded.

  Next, in transmission stop determination step 706, the received downlink frame 301-4 is analyzed by the channel codec unit 104 for RICH information defined by the system, and transmission stop information 601 is confirmed. If the information “11” of the transmission stop information 601 is not included, the process proceeds to a transmission process step 703 to continue transmission. This continuation of transmission will be described later. On the other hand, when the information “11” of the transmission stop information 601 is included, the process proceeds to the transmission stop process 707, and the system control unit 107 automatically stops the transmission of the mobile station M1. The method of stopping can be realized by stopping the operation of the modulation unit related to transmission in the modem unit 103, for example. In addition, the operator is notified of the suspension of transmission using character display using the display units 109 and 110, the buzzer 113, and the like, vision of light and the like, hearing of sounds and the like, and a sense by the vibration motor 112 and the like. Thereafter, the transmission process is stopped regardless of the press talk. Until the operator understands the state change and releases the press talk, the operator keeps informed of the state change, and when the press talk is released, the information related to these processes is reset.

  Next, a method in which the mobile station continues transmission when the transmission stop information 601 is not included as a result of the determination in the transmission stop determination step 706 described in FIG. 7 will be described with reference to FIG. In FIG. 10, 302-5 is an uplink voice frame UF from the mobile station M1, and shows an uplink voice frame in which transmission is temporarily stopped and then resumed. S indicates a transmission synchronization signal of the mobile station M1. . In addition, the same code | symbol is attached | subjected to the same thing as FIG.

  Thus, in the SCPC digital radio system, in general, the synchronization of the system is such that each mobile station M receives an empty line signal including a synchronization signal transmitted from the base station 801, and transmission / reception is performed in synchronization with this synchronization signal. What is done is well known. Therefore, the system control unit 107 shown in FIG. 1 detects a synchronization signal transmitted from the base station 801, generates a clock pulse in synchronization with this (not shown), and the system control unit 107 uses this clock pulse. Driven. Therefore, the transmission synchronization pulse S is also generated from this clock pulse, and the interval of the transmission synchronization pulse S is 40 ms, which is the same as the interval of the uplink voice frame UF. Also, the transmission synchronization pulse S is set 20 ms away from the head of the downstream audio frame 301 because an offset of 60 ms is set to the downstream audio frame DF. Therefore, the mobile station M1 generates uplink voice frames 302-1 and 302-2 based on the transmission synchronization pulse S and is talking.

  However, as described above, in the present invention, the mobile station M1 periodically stops transmission to the base station 801 during transmission to the base station 801, and broadcast information is transmitted from the downlink voice frame 301 from the base station 801. It is received and detected whether or not the transmission stop information “11” is included. These operations can be performed by the system control unit 107. In the case illustrated in FIG. 10, the broadcast information is received every four frames of the downlink frame 301. Therefore, when the broadcast information of the downlink frame 301-4 is received (position and period indicated by reception 303), the mobile station M1 stops transmission to the base station 801. When the broadcast stop information “11” is not included in the broadcast information of the downlink frame 301-4, the mobile station continues to transmit M1, but in this case, the uplink voice frame 302-3 Since 302 and 302-4 are missing, transmission starts from the upstream voice frame 302-5. The problem here is the problem of the synchronization of the uplink voice frame 302-5. Since the interval between the missing portions is 80 ms, the SCPC digital wireless system is particularly synchronized with this degree of lack. There will be no disruption of communication. Also, if the audio is missing about 2 frames (80 ms period), there is no particular problem with the content of communication. Note that if the transmission stop information detection period is set to about once every 10 frames instead of once every 4 frames, conversation interruptions are reduced, and there is no problem. Therefore, the optimum detection cycle can be appropriately set experimentally as the detection cycle in this type of system.

  Although the present invention has been described in detail above, the present invention is not limited to the embodiments of the digital radio system and the digital radio communication method described herein, and the digital radio system and the digital radio communication method other than those described above. Needless to say, it can be widely applied to.

It is a block diagram which shows schematic structure of one Example of this invention. It is a figure which shows the relationship of the upstream and downstream frame of this invention. It is a figure which shows the relationship of the transmission / reception frame for demonstrating one Example of this invention. It is a figure which shows the signal format of the audio | voice channel used by this invention. It is a figure which shows the bit arrangement | positioning of RICH used by this invention. It is a flowchart for demonstrating operation | movement of the base station of this invention. 4 is a flowchart for explaining the operation of the mobile station of the present invention. It is a schematic block diagram which shows an example of the conventional digital radio system. It is a figure which shows the frequency allocation of the radio carrier in the conventional digital radio system. It is a figure for demonstrating operation | movement of the mobile station of this invention.

Explanation of symbols

101: antenna, 102: RF unit, 103: modulation / demodulation unit, 104: channel codec unit, 105: audio codec unit, 106: audio input / output unit, 107: system control unit, 108: key input unit, 109: LED display unit 110: LCD display unit, 111: Memory, 112: Vibration motor unit, 113: Buzzer unit, DF, 301: Downstream audio frame, UF, 302: Upstream audio frame, 303 received frame, 601: Transmission stop information, 801: Base station, 802: communication area, M: mobile station, F1: downlink frequency, f1: uplink frequency.

Claims (1)

In an SCPC digital radio system having a base station and a plurality of mobile stations and performing communication between the base station and the plurality of mobile stations, the base station is one of the plurality of mobile stations. When communicating with a mobile station using a plurality of consecutive uplink voice frames and a plurality of downlink voice frames including broadcast information, the base station transmits a plurality of predetermined downlink voices among the plurality of consecutive downlink voice frames. Insert the transmission stop information of the mobile station that performs the communication into the frame, and set the predetermined number of frames n of the plurality of downlink voice frames in the mobile station that performs the communication. For example, the mobile station continues transmission processing, performs detection processing of the transmission stop information every nth predetermined frame, and stops transmission of the mobile station based on the transmission stop information. Tal wireless communication method.

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