JP2006101546A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a difference in line connection facilitation between a mobile station located in a communication zone of a control station and a mobile station located in a relay station zone, since it takes a long time to process a signal for connection with a relay station by a radio channel when the control station and the repeater station are connected by the radio channel in a digital radio relay system having the control station, the relay station and mobile stations. <P>SOLUTION: The control station comprises a timing control part for adjusting a communication timing when performing communication between the mobile station located in the communication zone of the control station and the mobile station located in the relay station zone, thereby adjusting the difference between a line connection time of the control station and the mobile station in the control station zone and a line connection time of the control station and the mobile station in the relay station zone. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a digital radio communication system, and more particularly to a digital radio relay system having a relay station and a radio relay system using a digital radio relay system.

  As shown in FIG. 6, a digital radio relay system that is currently in practical use includes a control station 51 and a plurality of mobile stations M1, M2 in a communication area 52 (also referred to as a communication zone) of the control station 51, , Or a plurality of mobile stations m1, m2,... And a control station 51 or a plurality of mobile stations M1, M2,... Within the communication area 54 of the relay station 53 The system is configured to perform the communication connection service. Note that the base station 55 may be installed in the vicinity of the control station 51, or may be installed at a remote location. When installed in a remote place, the control station 51 and the base station 55 are generally connected by a wired or micro line. In the case of FIG. 6, the control station 51 and the base station 55 are shown installed in the same place. The control station 51 maintains and manages a communication connection and a service area between a base station, a relay station, and a plurality of mobile stations in the digital radio relay system. In this control station 51, a line control device is installed, and call control from the mobile station or setting of a communication route is performed. In FIG. 6, the relay station 53 is located in the communication area 52 of the control station 51, but is not necessarily located in the communication area 52. That is, when the control station 51 and the relay station 53 are connected by a micro multiplex line or a digital dedicated line, the relay station 53 does not need to be located in the communication area 52.

  Thus, FIG. 7 shows radio carrier frequency allocation permitted for use in a narrowband digital radio system (including a digital radio relay system) including a regional disaster prevention radio system using digital radio technology in Japan. In FIG. 7, 160 waves (f1, f2,...) Are recognized in the 4 MHz band with a width of 25 KHz with reference to 262 MHz in the uplink direction, that is, in the direction of mobile station → relay station → control station. . Also, in the downstream direction, that is, in the direction of the control station → relay station → mobile station, 160 MHz (F1, F2,... ) Is allowed. Therefore, in the communication of the digital radio relay system, each frequency in the uplink direction f1, f2,..., Downlink 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. Needless to say, such frequency allocation varies from region to region and country, but the standard for digital radio systems in Japan is ARIB (Association of Radio Industries and Businesses) Standard-T79 (issued in September 2001, (Publisher: Radio Industry Association) (hereinafter referred to as ARIB STD).

  In such a digital wireless relay system, when performing wireless communication between mobile stations in different zones such as the control station zone and the relay station zone, as in the analog wireless communication system, the mobile station in the relay station zone, For example, the mobile station m1 performs wireless communication with a mobile station in the zone of the control station 51, for example, the mobile station M1 via the relay station 53. For this wireless communication, a wireless communication line controlled by a line control device of a control station is used.

FIG. 4 shows a configuration of a digital wireless relay system that is a conventional example. FIG. 4 illustrates the operation when the mobile station M1 in FIG. 6 calls the mobile station m1. First, the operation will be described in the downlink direction, that is, in the direction of control station → relay station → mobile station. When there is a call (connection request) from the mobile station M1, the control station 51 (or in some cases, via the base station 55) detects the call, and the control station 51 moves via the relay station 53. It is necessary to establish a call route with the station m1. First, when the control station 51 detects a call from the mobile station M1, the control station 51 connects the line controller 401 and the line I / F (interface) 404 of the relay station 400 to a digital dedicated line or a micro-multiplexed radio line. The connection is made through the transmission line 415 used.

  Thus, the transmission signal TS propagating through the transmission path 415 is a frame-structured digital signal and is represented by the transmission signal TS in FIG. In FIG. 8, one frame is 40 msec, and the transmission signal TS is formed by repeating this frame. One frame is composed of eight channels (CH1, CH2,... CH8), and the length of one channel is 5 msec. For example, CH1 is a control channel, and CH2 to CH8 are used as communication channels, for example.

  First, a signal received by the line I / F 404 using the control channel is applied to a data transposing unit 406 (hereinafter referred to as a data converting unit 406). In this data conversion unit 406, transmission format conversion is performed in order to establish a wireless connection with a mobile station located in the relay station zone. That is, it operates in synchronization with the line control device 401 at the timing obtained from the timing generation unit 405, and is converted into a control channel signal in the radio section based on the control of the control unit 407. That is, as shown in FIG. 8, the transmission signal TS of 1 frame and 8 channels is converted into two types of transmission signals C1 and C2 of 1 frame and 4 channels. Here, one frame of the transmission signals C1 and C2 is 40 msec, which is the same length as one frame of the transmission signal TS, but the channel lengths of the transmission signals C1 and C2 are each 10 msec.

  The control channel whose format has been converted by the data conversion unit 406 is a coder / decoder circuit 414 (hereinafter, the coder / decoder circuit is abbreviated as a channel codec), an error correction code according to a preamble, a synchronization word, a control signal, a standard, etc. Is added, and coding (encoding) is performed. The encoded control channel signal is applied to transmission modulation section 411-1 and converted into a signal capable of digital wireless communication with the mobile station. In the ARIB STD, this control channel is a radio channel composed of common use slots, and this is defined as a control channel.

  On the other hand, the signal received by the line I / F 404 using the communication channel is applied to the data conversion unit 406 as in the case of the control channel described above. The signal of the communication channel applied to the data conversion unit 406 operates in synchronization with the line control device 401 at the timing obtained from the timing generation unit 405, and is transmitted based on the control of the control unit 407 as shown in FIG. Only audio data is extracted from the signal TS, and CH2 to CH4 are converted into a transmission signal C1, and CH5 to CH8 are converted into a transmission signal C2 and supplied to a channel codec 414. In the channel codec 414, a preamble, a synchronization word, an error correction code, and the like are added to the communication channels of the transmission signals C1 and C2, and coded to be a baseband signal in a radio section. Transmission signals C1 and C2 are applied to transmission modulation sections 411-1 and 411-2, respectively. The transmission signals C1 and C2 applied to the transmission modulation units 411-1 and 411-2 are converted into signals capable of digital wireless communication with the mobile station and amplified by the power amplification units 410-1 and 410-2. Thereafter, the signal is supplied to the antenna 408 via the transmission filter 409. As a result, the transmission signals C1 and C2 are output from the antenna 408 at the frequencies F1 and F2 as downlink communication waves as described above. As a result, the antenna 408 of the relay station and the antenna 402 of the mobile station are connected by a digital radio link. In the mobile station, the transmission / reception device 403 can receive the control channel signal and the communication channel signal from the relay station. Here, in the ARIB STD, the communication channel is a radio channel composed of individual allocation slots, and this is defined as a communication channel.

  There are various digital modulation schemes used for the transmission modulation units 411-1 and 411-2, and a predetermined modulation scheme suitable for the digital radio communication system is used. For example, the π / 4 shift QPSK modulation method is a commonly used modulation method.

  Next, the operation in the uplink direction, that is, in the direction of mobile station → relay station → control station will be described. The signals of the above-described frequencies f1 and f2 transmitted from the transmission / reception device 403 via the antenna 402 are received as reception information by the antenna 408 of the relay station, are frequency-separated by the reception filter 413, are subjected to band limitation, and then received. Output to demodulation sections 415-1 and 415-2. Reception information is demodulated by reception demodulation sections 415-1 and 415-2 by a predetermined demodulation method, and is further output to channel codec 414. The channel codec 414 performs decoding (decoding) including error correction in accordance with a standard or the like (signal processing opposite to that in the downlink direction is performed), so that the received information is the transmission signal C1 in FIG. C2 is obtained, and a control channel signal and a communication channel signal are obtained. The control channel signal and the communication channel signal are applied to the data conversion unit 406, and the reverse conversion to the above-described downlink channel conversion is performed, and the transmission signal TS of FIG. 8 is obtained. After selecting necessary data, the control unit 407 transmits a selection signal from the line I / F 404 to the line control device 401 via the transmission path 415, and a communication route is established.

JP-A-10-107727 JP 63-074234 A

  The conventional digital wireless relay system described above has the following problems. (1) When connecting the line control device of the control station and the relay station with a digital leased line, you will be renting a digital line of another company, and there will be a usage fee. It grows and becomes a problem. (2) When connecting the line control device of the control station and the relay station with a digital dedicated line, there is a possibility that the digital dedicated line may be disconnected due to an external factor such as a disaster, especially in the case of a digital radio communication system for disaster prevention. In addition, the inability to use the system is a serious drawback in terms of reliability. (3) When the line control device of the control station and the relay station are connected by micro multiplex radio, the cost of the micro multiplex radio equipment is high, and the ratio of the cost of the micro multiplex radio equipment to the cost of the private radio communication system equipment In addition, there is a drawback that it is difficult for a self-employed user to introduce a micro multiplex radio facility because it requires a high level of worker qualification.

  The above-mentioned problems (1) to (3) can be improved by connecting the control station and the relay station via a wireless line. As a result, it is possible to provide a digital wireless system with high reliability and low maintenance cost in the event of a disaster. However, when the control station and the relay station are connected by a wireless line, there is a disadvantage that it takes time to process the signal for connecting to the relay station by the wireless line as described later. A new problem arises in that there is a difference in the ease of line connection between a certain mobile station and a mobile station in the relay station zone.

  Accordingly, an object of the present invention is to provide a digital radio relay system that can easily connect to a line by making it possible to eliminate this problem.

  In order to achieve the above object, a digital radio relay system of the present invention includes a control station having a line control unit, at least one first mobile station existing in a communication zone of the control station, a control station and a radio A relay station connected by a line and at least one second mobile station existing in the communication zone of the relay station, and the first and second mobile stations communicate with each other when the first and second mobile stations communicate with each other. The line control unit is provided with a timing control unit for adjusting the communication timing between the mobile stations.

  More specifically, the line control unit includes a storage unit that stores the communication area position where the first and second mobile stations are located, and the first mobile station location information is based on the location information of the first mobile station from the storage unit. The communication timing is delayed.

  Furthermore, the digital wireless relay system of the present invention has a base station, and the base station is located in the control station, so that the communication zone of the base station and the communication zone of the control station are common, so that the line control unit is The communication between the base station and the relay station is controlled.

  Furthermore, in the digital radio relay system of the present invention, the predetermined frequency band assigned to the communication between the control station and the first mobile station is the same as the predetermined frequency band assigned to the communication between the control station and the relay station. It is a thing.

  Further, the control station of the digital wireless relay system of the present invention includes a line control unit, a data conversion unit coupled to the line control unit for converting data of the transmission signal, and a data conversion unit coupled to the data conversion unit in a predetermined format. A first channel codec to be encoded / decoded and a first wireless transmission / reception unit that is coupled to the first channel codec and transmits / receives a transmission signal to / from the first mobile station. is there.

  Further, the relay station of the digital wireless relay system of the present invention is coupled to the second wireless transmitter / receiver that transmits and receives the transmission signal between the control unit and the relay station, and the second wireless transmitter / receiver that transmits the transmission signal to a predetermined level. A second channel codec that encodes / decodes in a format, a channel converter that is combined with the second channel codec to perform channel conversion of the transmission signal, and is combined with the channel converter to encode the transmission signal in a predetermined format A third channel codec to be decoded and a third wireless transmission / reception unit which is coupled to the third channel codec and transmits / receives transmission signals to / from the second mobile station.

  Further, the line control unit used in the control station of the digital radio relay system of the present invention includes the position information of the mobile station located in the communication area of the control station and the position of the mobile station located in the communication area of the relay station. A storage unit is provided for storing information, and the timing control unit adjusts the timing of communication between the first and second mobile stations based on the position information of the storage unit.

  Further, the wireless relay system when the first and second mobile stations communicate with each other in the digital wireless relay system of the present invention includes the steps of detecting the positions of the first and second mobile stations, and the first and second The position of the mobile station is composed of a step of adjusting the timing of communication between the first and second mobile stations based on the detection information.

  Furthermore, in the wireless relay system when the first and second mobile stations communicate with each other in the digital wireless relay system of the present invention, the line control device stores the communication area position where the first and second mobile stations are located. And a timing control unit that adjusts the timing of communication between the first and second mobile stations, so that the step of adjusting the timing is performed by the first mobile station from the storage unit. This is a step for delaying the communication timing of the first mobile station based on the position information.

  Further, in the wireless relay system when the first and second mobile stations communicate in the digital wireless relay system of the present invention, the steps of detecting the positions of the first and second mobile stations are the first and second steps. The mobile station determines whether or not it exists in the communication area of the control station depending on whether or not the line with the control station is connected, and the step of adjusting the timing is within the communication area of the control station. When present, the transmission timing of the control station is delayed by a predetermined time.

  Furthermore, in the wireless relay system when the first and second mobile stations communicate with each other in the digital wireless relay system of the present invention, the predetermined time is the same as the first mobile station in the communication zone of the control station. And the line connection time between the control station and the second mobile station located in the communication zone of the relay station via the relay station.

  According to the present invention, a digital radio relay system is provided for connecting a control station and a relay station via a radio line using a plurality of frequencies within a predetermined band. Compared with a system using a digital leased line or a micro-multiplexed line, the frequency can be effectively used.

  Further, compared to a system in which the control station and the relay station are connected by a digital dedicated line, there is less possibility of line disconnection due to a disaster, and a highly reliable digital wireless relay system can be realized.

  In addition, the running cost of the system can be significantly reduced as compared with a method of connecting with a digital dedicated line or a micro-multiplexed wireless line.

  Furthermore, the control station and the relay station are connected by a wireless line, but even when the mobile station in the control station zone and the mobile station in the relay station zone are connected, they respond at the same timing. Therefore, good connection control can be performed.

  In the digital wireless relay system, as described with reference to FIG. 6, mobile stations in the service area 52 of the control station 51 (or may be a communication area of the base station 55), for example, mobile stations M1 and M2 A relay station 53 is installed at a high place such as a summit, and is outside the service area 52 of the control station 51 and within the service area 54 of the relay station 53, for example, with the mobile station m1 There are cases where the mobile station M1 in the service area 52 of the control station 51 communicates. In the latter case, it is necessary to connect the transmission / reception device of the control station 51 and the transmission / reception device of the relay station. In such a case, since the number of channels of the relay station is generally plural, as described above, it is common to connect with a digital dedicated line or a micro-multiplexed radio line. However, when a digital dedicated line or a micro-multiplex radio line is adopted, there are problems that the system may become unusable at the time of a disaster and the maintenance cost becomes high. In order to solve this problem, the present invention employs a system in which a transmission / reception device of a control station and a transmission / reception device of a relay station are connected by a wireless line. That is, by installing a transmission / reception device in the control station, a sufficient service is ensured for mobile stations in the communication area of the control station, and a mobile station outside the communication area of the control station is connected by a wireless line. Sufficient service is provided through the relay station. Moreover, in the disaster prevention wireless communication system, such a wireless connection method is strongly demanded by users. In addition, a new problem arises that the connection between the mobile stations differs in the ease of line connection due to the connection via the wireless line as described above, but the present invention is a digital wireless relay system that also solves this problem. .

  Hereinafter, a digital wireless relay system according to an embodiment of the present invention will be described with reference to FIGS. 1, 2, 3, 5, 8, and 9. FIG. 1 is a block diagram showing a configuration of a digital radio relay system according to an embodiment of the present invention. FIG. 2 is a time chart showing the operation of the digital wireless relay system of this embodiment. FIG. 3 is a block diagram showing the configuration of the control station (control station 51 in FIG. 6) and the mobile station in the control station zone (mobile station M1 in FIG. 6) in the digital radio relay system of this embodiment. FIG. 5 is a block diagram showing the configuration of the control station (control station 51 in FIG. 6) in the digital radio relay system of the present embodiment. 8 and 9 are diagrams illustrating a frame configuration of a transmission signal.

  First, the configuration of the control station in FIG. 5 will be described. In FIG. 5, reference numeral 501 denotes a line control unit that performs line connection control of base stations, relay stations, and mobile stations, such as call control and call route establishment control. Further, the line control unit 501 has a memory 504, constantly monitors in which communication area the mobile station is located, and stores the position of each mobile station in the memory 504. In this monitoring method, for example, each mobile station has a different ID No. Is attached to the ID No. And the position information of the mobile station, it is determined whether the mobile station is located in the control station zone or the relay station zone, and is stored in the memory table 506 of the memory 504. Of course, this position information is updated as appropriate. The transmission / reception unit 502 is used for transmission / reception between the mobile station and the relay station in the control station. The control unit 505 performs control such as call control from a mobile station and setting of a communication route. The command console 503 is an operation console for the digital wireless relay system according to the present embodiment, and has functions for selecting voice and non-voice and managing the operation of the system.

  Next, the operation between the control station and the mobile station in the control station zone will be described with reference to FIG. Reference numeral 300 denotes a control station, 301 denotes an antenna, and 302 denotes a transmission / reception unit of a mobile station located in the control station zone. 303 is a line control unit, and 304 is a line I / F (interface) of the control station. The line control unit 303 and the line I / F 304 are directly connected by wire, and communication is performed using a control channel and a plurality of communication channels. Since the transmission / reception operation between the control station 300 and the transmission / reception unit 302 of the mobile station is the same as the transmission / reception operation between the relay station 400 and the transmission / reception unit 403 of the mobile station shown in FIG. explain.

In FIG. 3, the operation in the downlink direction (control station → mobile station in control station zone) will be described first. A transmission signal TS (same as TS in FIG. 8) including a control channel and a communication channel sent from the line control unit 303 is applied to the data conversion unit 306 via the line I / F 304. Then, the signal received using the control channel of the transmission signal TS is applied to the data transposing unit 306 (hereinafter referred to as the data converting unit 306). The data conversion unit 306 converts the transmission format in order to establish a wireless connection with a mobile station located in the control station zone. That is, it operates in synchronization with the line control unit 303 at the timing obtained from the timing generation unit 305, and is converted into a control channel signal in the radio section based on the control of the control unit 307. That is, as shown in FIG. 8, it is converted into two types of transmission signals C1 and C2. Here, the two types of transmission signals C1 and C2 employ a four-multiplex TDMA (Time Division Multiple Access) system, and one frame is configured by four slots. Details are defined in ARIB STD.

  The control channel whose format has been converted by the data converter 306 is a coder / decoder circuit 314 (hereinafter, the coder / decoder circuit is abbreviated as a channel codec), and an error correction code according to a preamble, a synchronization word, a control signal, a standard, and the like. Etc. are added and coding (encoding) is performed. The encoded control channel signal is applied to transmission modulation section 311-1 and converted into a signal capable of digital wireless communication with the mobile station.

  On the other hand, a signal received by the line I / F 304 using the communication channel is applied to the data conversion unit 306. Based on the control of the control unit 307, the communication channel signal applied to the data conversion unit 306 extracts only audio data from the transmission signal TS, as shown in FIG. , CH5 to CH8 are converted into a transmission signal C2 and supplied to the channel codec 314. Channel codec 314 adds a preamble, a synchronization word, an error correction code, and the like to the communication channels of transmission signals C1 and C2, encodes them, and applies them to transmission modulation sections 311-1 and 311-2, respectively. The transmission signals C1 and C2 applied to the transmission modulators 311-1 and 311-2 are converted into signals capable of digital wireless communication with the mobile station and amplified by the power amplifiers 310-1 and 310-2. Thereafter, the signal is supplied to the antenna 308 through the transmission filter 309. After being supplied to the antenna 308, the transmission signals C1 and C2 are output from the antenna 308 at frequencies F1 and F2 as downlink communication waves. As a result, the antenna 308 of the control station and the antenna 301 of the mobile station are connected by a digital radio link. In the mobile station, the transmission / reception unit 302 can receive a control channel signal and a communication channel signal from the control station.

  There are various digital modulation methods used for the transmission modulation units 311-1 and 311-2, and a predetermined modulation method suitable for the digital wireless relay system is used. For example, the π / 4 shift QPSK modulation method is a commonly used modulation method.

Next, the operation in the uplink direction (mobile station in control station zone → control station) will be described.
The signals of the above-described frequencies f1 and f2 transmitted from the transmitting / receiving unit 302 via the antenna 301 are received as reception information by the antenna 308 of the control station, are frequency-separated by the reception filter 313, and are subjected to band limitation, and then received. Output to demodulation sections 315-1 and 315-2. Reception information is demodulated by reception demodulation sections 315-1 and 315-2 by a predetermined demodulation method, and further output to channel codec 314. The channel codec 314 performs decoding (decoding) including error correction in accordance with the standard and the like, and performs signal processing opposite to the downlink direction, resulting in transmission signals C1 and C2 in FIG. And a communication channel signal is obtained. The control channel signal and the communication channel signal are applied to the data conversion unit 306, and reverse conversion to the above-described downlink channel conversion is performed to obtain the transmission signal TS of FIG. The control unit 407 selects necessary data from the transmission signal TS, and then transmits the data to the line control unit 303 from the line I / F 304 to establish a communication route.

  As described above, the operation of the control station 300 and the mobile station in the communication area of the control station 300 has been described. In this case, the timing when the control station 300 calls the mobile station in the communication area of the control station 300 Will be described with reference to FIG. FIG. 2 schematically represents the timing of calling among the control station, relay station, and mobile station, and represents the same transmission signal as the transmission signal C1 or C2 shown in FIG. That is, the first frame, the second frame,... Are repeated. Each frame is composed of four channels as described above. Here, the channel is referred to as a slot.

  In FIG. 2, if the control station 300 calls a mobile station in the communication area of the control station using slot 1 of the downlink transmission signal DS1 (the first slot of FLAME1), the transmission / reception unit 302 of the mobile station , It shows that it responds to the control station 300 using the slot 11 (the third slot of FLAME1) of the upstream transmission signal US1. This is because, as is apparent from the description of the operation of the control station 300 in FIG. 3, the response is delayed by 2 slots in order to perform signal processing such as data conversion. However, since all the mobile stations located in the communication area in the control station 300 have the same conditions, there is no difference in the call timing between the mobile stations located in the communication area in the control station 300. Therefore, there is no trouble in the line connection.

  Next, line connection of a mobile station located in the communication area of the relay station via the relay station will be described with reference to FIG. FIG. 1 shows communication between a control station 300 (shown in detail in FIG. 3) from a relay station 100 to a relay station 100 using a radio channel, and a mobile station transceiver within the communication area of the relay station 100. A case of communicating with 105 is shown. In FIG. 1, the operation in the downlink direction (control station → relay station → mobile station in relay station zone) will be described first. The signal transmitted from the antenna 308 of the control station 300 is transmitted at a frequency F1 as a communication wave in the downlink direction, similarly to the communication between the control station 300 and the mobile station in the communication area of the control station 300 described in FIG. , F2, and output from the antenna 308 and received by the antenna 106.

  The transmission signals of the frequencies F1 and F2 are separated by the reception filter 107 and band-limited, and then output to the reception demodulation units 111-1 and 111-2, respectively. Further, reception information is demodulated by reception demodulation sections 111-1 and 111-2 by a predetermined demodulation method and output to coder / decoder 113 (hereinafter, coder / decoder 113 is abbreviated as channel codec 113). The channel codec 113 performs error correction according to the standard and the like, decodes the received information, and obtains a control channel signal and a communication channel signal (the signals are shown as transmission signals C1 and C2 in FIG. 8). The control channel signal and the communication channel signal are applied to a slot replacement unit 115 (hereinafter abbreviated as a slot conversion unit 115).

  Thus, the control channel signal and the communication channel signal applied to the slot conversion unit 115 are transmitted to the radio section of the relay station 100 based on the synchronization timing of the timing generator 114 and the control of the control unit 116 in the slot conversion unit 115. It is converted into a control channel signal and a communication channel signal. That is, as shown in FIG. 9, the two transmission signals C1 and C2 are converted into one transmission signal C3. As is apparent from FIG. 9, a 2-system 8-channel signal is appropriately selected and converted into a 4-system 4-channel signal. For example, when the channel CH1 in the transmission signal C1 is a control signal and the channels CH3, CH6, and CH8 are communication channel signals, the transmission signal C3 includes channels CH1, CH3, CH6, and CH8. The reason why the number of channels may be small is that the control station needs to respond to calls from a large number of mobile stations or relay stations, so 8 channels are required. This is because only four mobile channels are sufficient because only the mobile stations in the network are targeted.

  Next, transmission signal C3 generated by slot converter 115 is applied to coder / decoder 123 (hereinafter, coder / decoder 123 is abbreviated as channel codec 123). In the channel codec 123, a preamble, a synchronization word, a control signal, an error correction code according to a standard, and the like are added to the control channel signal and the communication channel signal, respectively, and encoding is performed. The encoded transmission information is digitally modulated by the transmission modulation unit 119 and output as a transmission signal of the frequency F3 from the antenna 120 via the power amplification unit 118 and the transmission filter 117. There are various digital modulation methods used in the transmission modulation unit 119, and a predetermined modulation method suitable for a digital wireless communication system (including a digital wireless relay system) is used. For example, π / The 4-shift QPSK modulation method is a commonly used modulation method.

  The antenna 120 of the relay station 100 and the antenna 104 of the mobile station in the relay station 100 zone are connected by a digital radio link. In the mobile station in the communication area (relay zone) of the relay station 100, the transmission / reception unit 105 can receive the control channel signal and the communication channel signal from the control station.

  Next, the operation in the uplink direction (mobile station in relay station zone → relay station → control station) will be described. An information signal transmitted from the transmitting / receiving unit 105 of the mobile station in the communication area (relay station zone) of the relay station 100 as a transmission signal of the frequency f3 from the antenna 104 is received by the antenna 120 of the relay station 100 and is received by the reception filter 122. After being limited, the signal is input to the reception demodulation unit 124. The reception demodulation unit 124 demodulates the input signal using a predetermined demodulation method. The demodulated information signal is output to the channel codec 123. In the channel codec 123, an information signal is subjected to error correction or the like according to a standard and the like, and decoded to obtain a control channel signal and a communication channel signal. The control channel signal and the communication channel signal are applied to the slot converter 115. The slot conversion unit 115 performs slot conversion opposite to the above-described downlink direction. That is, as shown in FIG. 9, the transmission signal C 3 is converted into transmission signals C 1 and C 2 and applied to the channel codec 113.

  The channel codec 113 encodes the control channel signal and the communication channel signal by adding an error correction code according to a preamble, a synchronization word, a control signal, a standard, and the like, and transmits each as a baseband signal in the uplink radio section. It is sent to the modulators 112-1 and 112-2. This baseband signal is digitally modulated by transmission modulation sections 112-1 and 112-2 and output to power amplification sections 110-1 and 110-2. There are various digital modulation schemes used in the transmission modulation section, and a predetermined modulation scheme suitable for a digital radio communication system (including a digital radio relay system) is used. For example, π / 4 shift QPSK The modulation method is a commonly used modulation method. The transmission signal that has been digitally modulated and amplified is band-limited by the transmission filter 109 to become a transmission signal of the frequencies f1 and f2, and is output from the antenna 106. Transmission signals of frequencies f1 and f2 are received by the antenna 308 of the control station 300, and a communication route is established.

  The operation of the control station 300, the relay station 100, and the mobile station in the relay station area has been described above. In this case, the timing when the control station 300 calls the mobile station in the communication area of the relay station 100 is as follows. This will be described with reference to FIG. As described above, FIG. 2 schematically represents the call timing among the control station, relay station, and mobile station. In FIG. 2, the case where the control station 300 calls a mobile station in the communication area of the relay station 100 using slot 1 of the downlink transmission signal DS1 (first slot of FLAME1) will be described. First, when the control station 300 calls the relay station 100 using the slot 1 of the downlink transmission signal DS1 (the first slot of FLAME1), the relay station 100 uses the slot 33 of the downlink transmission signal DS2 ( The third slot) of FLAME1 is used for relaying, which is delayed by two slots. The reason for this delay is caused by a delay caused by reception processing at the relay station, as described above.

  Next, when the relay station 100 calls a mobile station in the communication area of the relay station 100 using the slot 33 of the transmission signal DS2, the transmission / reception unit 105 of the mobile station in the communication area (relay station zone) of the relay station 100 is called. Will respond using the slot 41 (first slot of FLAME2) of the upstream transmission signal US3. That is, it is delayed by two slots. This is caused by a delay for receiving processing inside the mobile station. Furthermore, when the response of the mobile station in the communication area (relay station zone) of the relay station 100 is made using the slot 41 of the uplink transmission signal US3, the relay station 100 will use the slot of the uplink transmission signal US2. 27 (the third slot of FLAME2) is used to respond to the control station 300. That is, it is delayed by two slots. This delay is a delay due to reception processing in the relay station 100. As a result, the response time when the mobile station in the communication area of the relay station 100 is called from the control station 300 via the relay station 100 is the response time when the mobile station in the communication area of the control station 300 is called. Compared to the four slots, that is, one frame later.

  As described above, when the control station 300 calls the mobile station in the communication zone of the control station 300 and the mobile station in the communication zone of the relay station 100 using the first slot in the downlink direction, the arrival timing of the response signal is controlled. The mobile station in the communication zone of the station 300 is the third slot delayed by 2 slots, whereas the mobile station in the communication zone of the relay station 100 is the seventh slot delayed by 6 slots. Therefore, the incoming timing of the response signal is delayed by 4 slots, that is, by 1 frame, when calling the mobile station in the relay station zone than when calling the mobile station in the control station zone. This delay is 40 msec, which is a serious problem in line connection. Also, when making a call, the call is uncomfortable.

  In order to solve this problem, in the digital radio relay system of this embodiment, as shown in FIG. 5, the line control unit 501 of the control station 51 is provided with, for example, a memory table 506, and each mobile station Is stored in which communication zone. When a call is made from a mobile station in the communication area of the relay station 100, for example, the mobile station m1, and a mobile station in the communication area of the control station 300, for example, the mobile station M1 is called, the control unit 505 of the line control unit 501 This can be realized by delaying the timing for calling the mobile station M1 by one frame. Note that the method of delaying by one frame can be easily realized by delaying, for example, 4 slots at the time of data conversion.

  As a method for specifying the position of the mobile station, an ID number is assigned to each mobile station, and the control station stores the ID number of the mobile station in the control station zone and the ID number of the mobile station in the relay station zone. The content of the memory table may be updated every time the mobile station moves its position.

  Furthermore, in the digital radio relay system of the present embodiment, as described above, if the radio frequency is assigned, the frequency can be effectively used. That is, in the case of the digital wireless relay system of this embodiment, two sets of frequencies, for example, the frequency in the upstream direction is f1, f2, and the frequency in the downstream direction is F1, F2. When communication is performed between the transmission / reception unit of the control station and the mobile station in the control station zone and when communication is performed between the transmission / reception unit of the control station and the transmission / reception unit of the relay station, f1 / F1 and f2 / F2 are set. assign. And when performing communication between the transmission / reception unit of the relay station and the transmission / reception unit of the mobile station in the relay station zone, by using the frequency f3 in the upstream direction and the frequency in the downstream direction as F3, Since the same frequency is assigned to the transmission / reception unit of the control station, the transmission / reception unit of the relay station to the control station, and the transmission / reception unit of the mobile station in the communication area of the control station, the frequency can be effectively used.

  In the digital radio relay system shown in FIG. 1, the frequencies (predetermined in-band frequencies) assigned to the transmission / reception unit of the relay station are (f1 / F1, f2 / F2) and f3 / F3, so that (f1 / F1 , F2 / F2) and f3 / F3 need to be as far as possible from each other. Therefore, it is necessary to sufficiently secure the attenuation characteristics of the transmission filters 109 and 117 and the reception filters 107 and 122 in the relay station. In order to reduce the influence of the transmission frequency (f1, f2) of the relay station 100 on the reception frequency f3, and to reduce the influence of the transmission frequency F3 of the relay station 100 on the reception frequency (F1, F2), it is usually 1 MHz. It is desirable to leave more than this. In addition, it is necessary to secure a sufficient distance between the antennas in the vertical and horizontal directions to secure a coupling attenuation amount.

1 is a block diagram showing the configuration of a digital radio relay system that is an embodiment of the present invention. The time chart which shows operation | movement of the digital radio relay system which is one Example of this invention. The block diagram which shows the structure of the control station in the digital radio relay system which is one Example of this invention, and the mobile station in a control station zone. The block diagram which shows the structure of the digital radio relay system which is an example of the past. The block diagram which shows the structure of the control station of the digital radio relay system which is one Example of this invention. The figure which shows schematic structure of a digital radio relay system. The figure which shows allocation of the radio | wireless carrier frequency used in a digital radio relay system. The figure which shows the frame structure of the transmission signal in the digital radio relay system which is one Example of this invention. The figure which shows the frame structure of the transmission signal in the digital radio relay system which is one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100: Relay station 104: Antenna 105: Transmission / reception part 106: Antenna 107: Reception filter 109: Transmission filter 110-1: Power amplification part 110-2: Power amplification part 111-1: Reception demodulation part 111-2: Reception demodulation part 112-1: Transmission modulation unit 112-2: Transmission modulation unit 113: Coder / decoder 114: Timing generator 115: Slot conversion unit 116: Control unit 117: Transmission filter 118: Power amplification unit 119: Transmission modulation unit 120: Antenna 122: reception filter 123: coder / decoder 124: reception demodulator DS1: transmission signal in the downlink direction (control station → relay station or mobile station) DS2: transmission signal in the downlink direction (relay station → mobile station) US1: uplink direction Transmission signal (mobile station → control station) US2: Uplink (relay station → control station) transmission signal US3: Transmission signal in the forward direction (mobile station → relay station) 1-7: Slot of the transmission signal in the downstream direction (control station → relay station or mobile station) 11: Slot of the transmission signal in the upstream direction (mobile station → control station) 21-27: Transmission signal slot in the upstream direction (relay station → control station) 31-37: Transmission signal slot in the downstream direction (relay station → mobile station) 41: Transmission signal in the upstream direction (mobile station → relay station) Slot 300: Control station 301: Antenna 302: Transmission / reception unit 303: Line control unit 304: Line I / F (interface)
305: Timing generation unit 306: Data transposition unit 307: Control unit 308: Antenna 309: Transmission filter 310-1: Power amplification unit 310-2: Power amplification unit 311-1: Transmission modulation unit 311-2: Transmission modulation unit 313: reception filter 314: coder / decoder circuit 315-1: reception demodulation unit 315-2: reception demodulation unit 400: relay station 401: line control device 402: antenna 403: transmission / reception unit 404: line I / F (interface)
405: Timing generation unit 406: Data transposition unit 407: Control unit 408: Antenna 409: Transmission filter 410-1: Power amplification unit 410-2: Power amplification unit 411-1: Transmission modulation unit 411-2: Transmission modulation unit 413: reception filter 414: coder / decoder circuit 415: transmission line 415-1: reception demodulation unit 415-2: reception demodulation unit 501: line control unit 502: transmission / reception unit 503: command console 504: memory 505: control unit 506: Memory table 51: Control station 52: Control station communication area 53: Relay station 54: Relay station communication area 55: Base station M1, M2: Mobile stations in the control station communication area m1, m2: Relay station communication Mobile stations in the area TS, C1, C2: Transmission signal

Claims (3)

A control station and at least one first mobile station located in the communication zone of the control station;
In a control station of a digital radio relay system in which a relay station connected to the control station via a radio channel and at least one second mobile station is located in a communication zone of the relay station,
The control station is coupled to the line control unit, the data conversion unit coupled to the line control unit to convert data of the transmission signal, and coupled to the data conversion unit to encode / decode the transmission signal in a predetermined format. A channel codec,
A radio transmission / reception unit coupled with the channel codec for transmitting / receiving the transmission signal via a radio line between a mobile station in the communication zone of the control station and a mobile station in the communication zone of the relay station; Prepared,
The control station of the digital radio relay system, wherein the line control unit adjusts the timing of communication between the mobile stations.
The control station according to claim 1,
The line control unit includes a storage unit that stores position information of a mobile station in a communication area, and a timing control unit that adjusts the timing of communication between the mobile stations based on the position information of the storage unit. Control station of digital wireless relay system.
A digital radio relay including a control station having a line control device, at least one relay station, and at least one mobile station, wherein the mobile station moves in a communication zone of the control station and in a communication zone of the relay station A system,
Determining means for determining whether the mobile station exists in a communication area of the control station when the mobile station connects to the control station;
Delay means for delaying the transmission timing of the control station for a predetermined time when it is determined that the mobile station exists in the communication area of the control station;
The predetermined time by the delay means is the line connection time between the control station and the first mobile station in the communication zone of the control station,
A digital radio relay system characterized in that the control station is approximately equal to a difference in line connection time with a second mobile station located in the communication zone of the relay station via the relay station.

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