JP7297030B2 - Wireless communication system, terminal wireless device and base station device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a wireless communication system, and more particularly, includes a headquarters station apparatus and a plurality of base station apparatuses connected to the headquarters station apparatus in a tree configuration and communicating with terminal wireless apparatuses. The present invention relates to a radio communication system in which a base station apparatus and a terminal radio apparatus communicate in units of frames with a constant period.

2. Description of the Related Art A radio communication system is known in which a plurality of base station apparatuses are connected to a central station apparatus in a tree configuration, and the central station apparatus, the plurality of base station apparatuses, and a terminal radio apparatus communicate in units of frames at a constant cycle.

In the prior art (see Patent Documents 1 and 2, for example), in a state in which the headquarters station apparatus and the base station apparatus are connected, the headquarters station apparatus and a plurality of base stations are connected to adjust the timing of the downlink and the uplink. By measuring the delay time between station devices and setting the time obtained by subtracting the delay time of the own station from the maximum delay time corresponding to the delay time of the farthest base station device, the terminal wireless device can Simultaneous transmission from multiple stations was performed.

JP-A-2002-27534 JP 2007-166278 A

In the conventional technology, the circuit delay time between the central office equipment and each base station equipment is measured in a state where the central office equipment and a plurality of base station equipment are connected, and the delay time of each circuit is equal to each base station equipment. Simultaneous transmission from multiple stations was realized by suspending transmission at the device.

Therefore, when a base station device whose line with the headquarters station device has been cut off performs base station return communication, the timing of transmission of downlink signals deviates from that of other base station devices. Simultaneous multi-station transmission with station equipment could not be maintained.

A terminal radio located in an area where radio waves can be received from both the base station equipment connected to the headquarters equipment (normal base station equipment) and the base station equipment disconnected from the headquarters equipment (return base station equipment). A device receives downstream signals from two different routes (first and second routes). If the timing of downlink signals passing through these routes is shifted, interference of voice signals will occur, and the terminal wireless device 30 will not be able to receive the signals normally. Here, the first route is a route that relays in the order of the normal base station device, the headquarters station device, and the normal base station device. A second route is a route that is returned by the return base station apparatus.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and enables a base station device whose line to the headquarters station device has been cut off to perform multi-station simultaneous transmission together with other normal base station devices. The purpose is to provide an efficient wireless communication system.

A base station apparatus according to the present invention includes a headquarters station apparatus, a plurality of base station apparatuses connected to the headquarters station apparatus in a tree configuration and operating based on a common synchronization signal , and radio communication with the base station apparatus. and a terminal radio device capable of When there is no call , another base station device that performs base station return communication transmits a downlink signal in a second format that includes the synchronization word and does not include the user channel to the terminal radio device, The wireless device receives the downlink signal in the first format and the downlink signal in the second format during non-communication.

According to the radio communication system according to the present invention, it is possible to suppress interference between downlink signals of a base station apparatus performing base station loopback communication and downlink signals of normal base station apparatuses when there is no call, It is possible to suppress the occurrence of a deviation in synchronization of the terminal wireless device.

1 is a schematic diagram showing a configuration of a radio communication system according to Embodiment 1 and a communication state during normal operation; FIG. 2 is a block diagram showing the configuration of a central station apparatus according to Embodiment 1; FIG. 2 is a block diagram showing the configuration of a base station apparatus according to Embodiment 1; FIG. 2 is a diagram showing a hardware configuration of a central station apparatus according to Embodiment 1; FIG. 2 is a diagram showing a hardware configuration of a base station apparatus according to Embodiment 1; FIG. FIG. 2 is a diagram showing transmission timings of downlink signals in the wireless communication system during normal operation according to Embodiment 1; 1 is a schematic diagram showing a configuration of a wireless communication system according to Embodiment 1 and a communication state when a line is disconnected; FIG. FIG. 4 is a diagram showing a sequence of return delay time measurement in the radio communication system according to Embodiment 1; 4 is a diagram showing transmission timings of downlink signals in the radio communication system when a line is disconnected according to Embodiment 1. FIG. 4 is a flow chart showing the operation of the radio communication system according to Embodiment 1; FIG. 10 is a diagram showing a frame format transmitted by a normal base station apparatus according to Embodiment 2 when there is no call; FIG. 10 is a diagram showing a frame format transmitted by a base station apparatus with a disconnected line to a headquarters station apparatus according to Embodiment 2 when there is no call; FIG. 12 is a block diagram showing the configuration of a base station apparatus according to Embodiment 3; FIG. 10 is a diagram showing transmission timings of broadcast information in a wireless communication system according to Embodiment 3; FIG. 10 is a diagram showing transmission timings of generation numbers of broadcast information in a wireless communication system according to Embodiment 4;

<Embodiment 1>
<Configuration>
FIG. 1 is a diagram showing the configuration of a radio communication system according to the first embodiment. As shown in FIG. 1, the radio communication system according to the first embodiment includes a headquarters station apparatus 10 and first to third base station apparatuses 201, 202, and 203. FIG. First to third base station devices 201, 202, and 203 are connected to the headquarters station device 10 in a tree configuration. The first to third base station devices 201 , 202 and 203 communicate with the terminal radio device 30 . Hereinafter, the first to third base station apparatuses 201, 202, and 203 are simply referred to as base station apparatus 20 when they are not distinguished from each other.

In the radio communication system according to Embodiment 1, the headquarters station apparatus 10, the plurality of base station apparatuses 20, and the terminal radio apparatus 30 communicate in frame units at a constant cycle. The wireless communication system according to the first embodiment is a system that performs press-to-talk voice communication.

The headquarters station device 10 is a device that accommodates a plurality of base station devices 20 and controls a wireless communication system. Each base station device 20 is connected to the terminal radio device 30 via a radio line, and performs voice signal relay and radio line control with the headquarters station device 10 .

An area R1 shown in FIG. 1 is an area where communication with the first base station apparatus 201 is possible and where radio wave interference from the second base station apparatus 202 is not received. An area R2 shown in FIG. 1 is an area where communication with the second base station apparatus 202 is possible and an area where radio wave interference from the first base station apparatus 201 is not received. Area R3 shown in FIG. 1 is an area where communication with both first and second base station apparatuses 201 and 202 is possible.

The uplink signal transmitted from the terminal radio equipment 30 is looped back by the central office equipment 10 and transmitted to all the base station equipment 20 as downlink signals. Here, an uplink signal means a signal that is transmitted from the terminal wireless device 30, the base station device 20, and the headquarters station device 10 in this order. A downlink signal is a signal that is transmitted from the headquarters station apparatus 10, the base station apparatus 20, and the terminal radio apparatus 30 in this order.

It is assumed that downlink signals from each base station apparatus 20 are transmitted using the same frequency. It is also assumed that uplink communication from the terminal radio device 30 to each base station device 20 is also transmitted using the same frequency.

FIG. 2 is a block diagram showing the configuration of the central station apparatus 10 according to the first embodiment. As shown in FIG. 2 , the headquarters station device 10 includes a return processing section 11 , a control section 12 , a downlink transmission timing adjustment section 13 and a base station communication section 14 .

The loop processing unit 11 has a function of receiving an uplink signal from the base station device 20 via the base station communication unit 14, looping back the signal and transmitting the signal to the plurality of base station devices 20 via the base station communication unit 14.

The control unit 12 generates information necessary for the terminal wireless device 30 to communicate, and notifies the terminal wireless device of the information via the base station device 20 . Also, the control unit 12 controls each unit in the central office device 10 .

The downlink transmission timing adjustment section 13 includes a simultaneous transmission available time determination section 131 and a transmission suspension time determination section 132 . Simultaneous transmission possible time determination section 131 determines a time during which multiple base station apparatuses 20 can simultaneously transmit in order to realize multi-station simultaneous transmission. The transmission suspension time determination unit 132 determines the transmission suspension time for each of the plurality of base station devices 20. receive.

FIG. 3 is a block diagram showing the configuration of base station apparatus 20 according to the first embodiment. As shown in FIG. 3, the base station apparatus 20 includes a higher station communication unit 21, an uplink communication processing unit 22, a return processing unit 23, a downlink communication processing unit 24, a downlink transmission timing adjustment unit 25, a control unit 26, a lower station communication 27 and a terminal radio device communication unit 28 .

The higher station communication unit 21 receives a signal from the central station device 10 directly or via the higher base station device 20 . Also, the upper station communication unit 21 transmits a signal to the headquarters station apparatus 10 or the upper base station apparatus 20 .

The uplink communication processing unit 22 normally relays signals received from the terminal radio device 30 or the lower base station device 20 to the headquarters station device 10 or the higher base station device 20 . Further, the uplink communication processing unit 22 transmits the signal received from the terminal wireless device 30 or the lower base station device 20 to the return processing unit 23 when the upper line is disconnected.

When the upper line is disconnected, the return processing unit 23 transmits the signal received from the upstream communication processing unit 22 to the downstream communication processing unit 24 when the time obtained by adding the return delay time and the transmission suspension time has elapsed. do.

The downlink communication processing unit 24 normally transmits a signal received from the headquarters station device 10 or the upper base station device 20 to the terminal radio device 30 or the lower base station device 20 . Further, the downlink communication processing unit 24 transmits the signal received from the return processing unit 23 to the terminal wireless device 30 or the lower base station device 20 when the upper line is disconnected.

The downlink transmission timing adjustment section 25 includes a line delay time measurement section 251 , a return delay time measurement section 252 , a transmission hold time storage section 253 and a return delay time storage section 254 .

The line delay time measuring section 251 measures the line delay time between the headquarters station apparatus 10 and the base station apparatus 20 in order to realize multi-station simultaneous transmission. Return delay time measuring section 252 measures the line delay time received by base station apparatus 20 after the signal from base station apparatus 20 is returned by central office apparatus 10 .

The transmission suspension time storage unit 253 stores the transmission suspension time notified from the headquarters device 10 .

A return delay time storage unit 254 stores a return delay time. The control unit 26 processes and stores the notification information received from the headquarters device 10 . Also, the control unit 26 controls each processing unit in the base station apparatus 20 .

The lower station communication unit 27 has a function of transmitting a signal received from each processing unit to the lower base station device 20, and has a function of transmitting a signal received from the lower base station device 20 to each processing unit. The terminal radio device communication unit 28 has a function of transmitting a signal received from each processing unit to the terminal radio device 30, and has a function of transmitting a signal received from the terminal radio device 30 to each processing unit.

FIG. 4 is a diagram showing the hardware configuration of the headquarters device 10. As shown in FIG. The base station communication unit 14 is realized by the base station communication circuit HW11. The loopback processing unit 11, the control unit 12, and the downstream transmission timing adjustment unit 13 are realized by the processing circuit HW12 and the memory HW13. The processing circuit HW12, even if it is dedicated hardware, is a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, microcontroller, processor) that executes the program stored in the memory HW13. , DSP).

If processing circuit HW12 is dedicated hardware, processing circuit HW12 may be, for example, a single circuit, multiple circuits, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. .

When the processing circuit HW12 is a CPU, the functions of the return processing unit 11, the control unit 12, and the downstream transmission timing adjustment unit 13 are realized by software, firmware, or a combination of software and firmware. Software and firmware are written as programs and stored in the memory HW13. The processing circuit HW12 realizes the functions of the return processing unit 11, the control unit 12, and the downstream transmission timing adjustment unit 13 by reading and executing the program stored in the memory HW13. It can also be said that this program causes a computer to execute the procedures and methods of the return processing section 11 , the control section 12 and the downstream transmission timing adjustment section 13 . Here, the memory HW 13 is, for example, non-volatile or volatile semiconductor memory such as RAM, SDRAM, ROM, flash memory, EPROM, EEPROM, magnetic disk, flexible disk, optical disk, compact disk, mini disk, DVD etc.

Note that the functions of the return processing unit 11, the control unit 12, and the downstream transmission timing adjustment unit 13 may be partly realized by dedicated hardware and partly by software or firmware.

FIG. 5 is a diagram showing the hardware configuration of the base station device 20. As shown in FIG. The higher station communication unit 21 is implemented by a higher station communication circuit HW21. The lower station communication unit 27 is realized by the lower station communication circuit HW22. The terminal radio device communication unit 28 is realized by the terminal radio device communication circuit HW23. Uplink communication processing unit 22, return processing unit 22, downlink communication processing unit 24, downlink transmission timing adjustment unit 25 and control unit 26 are realized by processing circuit HW24 and memory HW25. The processing circuit HW24, even if it is dedicated hardware, is a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, microcontroller, processor) that executes the program stored in the memory HW25. , DSP).

If processing circuit HW24 is dedicated hardware, processing circuit HW24 may be, for example, a single circuit, multiple circuits, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. .

When the processing circuit HW 24 is a CPU, the functions of the upstream communication processing unit 22, the return processing unit 22, the downstream communication processing unit 24, the downstream transmission timing adjustment unit 25, and the control unit 26 are implemented by software, firmware, or a combination of software and firmware. Realized. Software and firmware are written as programs and stored in the memory HW25. The processing circuit HW24 performs the functions of the upstream communication processing unit 22, the return processing unit 22, the downstream communication processing unit 24, the downstream transmission timing adjustment unit 25, and the control unit 26 by reading and executing the programs stored in the memory HW25. come true. It can also be said that this program causes a computer to execute the procedures and methods of the uplink communication processing unit 22, loopback processing unit 22, downlink communication processing unit 24, downlink transmission timing adjustment unit 25, and control unit . Here, the memory HW 25 includes, for example, nonvolatile or volatile semiconductor memories such as RAM, SDRAM, ROM, flash memory, EPROM, and EEPROM, magnetic disks, flexible disks, optical disks, compact disks, minidisks, DVDs, etc. etc.

The functions of the upstream communication processing unit 22, loopback processing unit 22, downstream communication processing unit 24, downstream transmission timing adjustment unit 25, and control unit 26 are partly realized by dedicated hardware, and partly by software or firmware. It may be realized by

<Normal operation>
First, the operation of the wireless communication system during normal operation will be described. Here, "normal" means that there is no disconnection of the line between the headquarters station device 10 and the base station device 20 being served.

FIG. 6 is a diagram showing transmission timings of downlink signals in a wireless communication system in normal operation. The timing in the upper part of FIG. 6 is 1PPS (1-second pulse) received from GPS (Global Positioning System) satellites. The headquarters station apparatus 10 and all the base station apparatuses 20 perform signal processing based on 1PPS received from GPS satellites as a synchronization signal. Each of the headquarters station apparatus 10 and all the base station apparatuses 20 has a synchronization signal reception section (not shown), and the synchronization signal reception section receives the synchronization signal.

The downstream signal transmitted from the central station apparatus 10 is delayed by the signal processing time inside the central station apparatus 10 with the 1PPS standard as the starting point. This is defined as offset time. In the example of FIG. 6, the offset time is 4 ms. In addition, line delay time occurs as the time until the base station apparatus 20 receives the downlink signal transmitted from the headquarters station apparatus 10 .

In the example of FIG. 6, the line delay times of the first to third base station apparatuses 201, 202 and 203 are 41 ms, 66 ms and 86 ms, respectively. From this, it can be seen that the arrival of the signal to the third base station apparatus 203 is the most delayed. Also, as shown in FIG. 6, the time from reception of the downlink signal by the third base station apparatus 203 to the next transmittable frame is 30 ms.

The simultaneous transmission possible time is the time from when the central station apparatus 10 transmits a downlink signal to when all the base station apparatuses 20 can perform simultaneous transmission of the downlink signal. The simultaneous transmission possible time is determined based on the line delay time (86 ms) of the third base station apparatus 203 in which the arrival of the signal is delayed the most. In other words, the simultaneous transmission possible time is the offset time (4 ms) inside the headquarters station device 10, the line delay time (86 ms) of the third base station device 203 where the arrival of the signal is delayed the most, and the third base station device 203 is calculated by adding the time (30 ms) from the reception of the downstream signal to the next transmittable frame. In the case of FIG. 6, the simultaneous transmission possible time is 120 ms.

A method for measuring the simultaneous transmission available time will be described. The headquarters station apparatus 10 transmits a line delay time measurement instruction to all base station apparatuses 20 (first to third base station apparatuses 201, 202, 203) being served. This instruction includes the time when the central office device 10 transmitted the instruction.

The line delay time measuring section 251 of each base station apparatus 20 that has received the line delay time measurement instruction returns the time (downlink signal reception timing) at which the instruction was received to the headquarters station apparatus 10 . Alternatively, the line delay time measurement unit 251 may calculate the line delay time by subtracting the time when the central station device 10 transmitted the instruction from the time when the instruction was received, and may respond with the line delay time.

Upon receiving the downlink signal reception timing from each of the base station apparatuses 20 being served, the headquarters station apparatus 10 calculates the channel delay time for each base station apparatus 20 . Note that when the affiliated base station apparatus 20 responds with the line delay time, the headquarters station apparatus 10 does not need to calculate the line delay time.

Based on the base station device 20 (the third base station device 203 in the example of FIG. 6), the headquarters station device 10 determines the timing of the frame in which the downlink signal can be transmitted as a simultaneous transmission possible time. Determined as In the example of FIG. 6, the simultaneous transmission possible time is 120 ms.

Next, the transmission suspension time determination unit 132 of the central office device 10 calculates the time (transmission suspension time) during which the transmission of the downlink signal is suspended after each base station device 20 receives the downlink signal. The transmission suspension time of each base station device 20 is calculated as a time obtained by subtracting the line delay time and the offset time from the simultaneous transmission possible time.

In the example of FIG. 6, the transmission suspension time of the first base station apparatus 201 is 75 ms by calculation of 120 ms-4 ms-41 ms. The transmission hold time of the second base station apparatus 202 is 50ms by calculation of 120ms-4ms-66ms. The transmission suspension time of the third base station apparatus 203 is 30 ms by calculation of 120 ms-4 ms-86 ms.

Then, the headquarters station device 10 notifies the corresponding base station device 20 of the transmission suspension time of each base station device 20 . Upon receiving the transmission suspension time, each base station device 20 stores the transmission suspension time in the transmission suspension time storage unit 253 . In the example of FIG. 6, 75 ms, 50 ms, and 30 ms are stored in the transmission suspension time storage units 253 of the first to third base station apparatuses 201, 202, and 203, respectively.

Also, instead of the head office apparatus 10 calculating the transmission suspension time, each base station apparatus 20 may calculate the transmission suspension time. In this case, the headquarters station device 10 transmits the simultaneous transmission available time and the offset time to each base station device 20, and each base station device 20 calculates and stores the transmission suspension time using the line delay time.

Each base station device 20 being served by the central office device 10 transmits a downlink signal when the transmission suspension time has elapsed after receiving the downlink signal. As a result, when the simultaneous transmission possible time (120 ms in the example of FIG. 6) has elapsed from 1PPS as a starting point, each base station apparatus 20 simultaneously transmits downlink signals. By the above operation, synchronization is maintained on the radio channel, and simultaneous transmission from multiple stations becomes possible.

<Operation when the line is disconnected>
Next, the operation of the wireless communication system when communication between the headquarters station apparatus 10 and the base station apparatus 20 is disconnected will be described. FIG. 7 is a schematic diagram showing the communication state of the wireless communication system when the line is disconnected. In FIG. 7, the line is disconnected between the headquarters station device 10 and the second base station device 202 . The second base station device 202 continues the communication service in the area R2 by performing base station return communication by returning the signal (voice) independently.

In the conventional technology, the first base station device 201 (normal base station device) connected to the headquarters station device 10 and the second base station device 202 (normal base station device) disconnected from the headquarters station device 10 In the area R3 where both radio waves of the return base station apparatus) are received, interference of downlink signals has occurred.

A terminal radio device 30 located in area R3 receives downlink signals from two different routes (first and second routes). If the timing of downlink signals passing through these routes is shifted, interference of voice signals will occur, and the terminal wireless device 30 will not be able to receive the signals normally. Here, the first route is a route relayed in the order of first base station device 201, headquarters station device 10, and first base station device 201. FIG. A second route is a route that loops back at second base station apparatus 202 . The first embodiment solves the above problem.

In the first embodiment, all the base station devices 20 under the control of the central station device 10 measure the return delay time in advance in a state where the line with the central station device 10 is connected (that is, in a normal state). . FIG. 8 is a diagram showing a sequence for measuring the return delay time. In FIG. 8, only the sequence related to the first base station apparatus 201 is shown for ease of viewing.

The headquarters station apparatus 10 transmits a return delay time measurement instruction to all base station apparatuses 20 (first to third base station apparatuses 201, 202, and 203) being served thereby. Upon receiving the return delay time measurement instruction, the first base station apparatus 201 transmits a delay time measurement signal to the central station apparatus 10 . Upon receiving the delay time measurement signal from first base station apparatus 201 , headquarters station apparatus 10 performs loopback processing and transmits the delay time measurement signal to first base station apparatus 201 . The loopback process requires the signal processing time (offset time) inside the central station apparatus 10 .

Upon receiving the delay time measurement signal, the return delay time measurement unit 252 of the first base station apparatus 201 calculates the return delay time using the time at which the first base station apparatus 201 transmitted the delay time measurement signal to the headquarters station apparatus 10. to measure. Specifically, the return delay time determination unit 252 calculates the return delay time by subtracting the time when the delay time measurement signal is transmitted from the time when the delay time measurement signal is received. Then, the return delay time is stored in the return delay time storage unit 254 .

Although the return delay time of the first base station apparatus 201 has been described above, the return delay times of the second and third base station apparatuses 202 and 203 are similarly determined and stored in the return delay time storage unit 254. be.

FIG. 9 is a diagram showing transmission timings of downlink signals in a wireless communication system when a line is disconnected. In FIG. 9, as in FIG. 6, the central station apparatus 10 and all the base station apparatuses 20 perform signal processing based on 1PPS. As shown in FIG. 9, the first and third base station devices 201 and 203 under the control of the central office device 10 receive the downlink signal returned by the central office device 10, and when the transmission suspension time elapses, , to transmit downstream signals.

Further, the second base station device 202 under the control of the headquarters station device 10 receives the uplink signal from the terminal radio device 30, and when the time obtained by adding the transmission hold time to the return delay time elapses, the terminal radio The downstream signal is returned and transmitted to the device 30 . As a result, the second base station apparatus 202 whose line is disconnected can transmit signals in synchronization with the normal base station apparatuses (first and third base station apparatuses 201 and 203) at the same timing. It is possible.

FIG. 10 is a flow chart showing the operation of the base station apparatus 20. As shown in FIG. In a state (normal state) where the line with the central station device 10 is not disconnected, the base station device 20 executes steps S1 to S4 in advance. That is, the base station device 20 receives the transmission suspension time from the headquarters station device 10 and stores it in the transmission suspension time storage unit 253 (steps S1 and S2). The base station apparatus 20 also measures the return delay time and stores it in the return delay time storage unit 254 (steps S3 and S4).

Next, in step S5, the base station device 20 receives an uplink signal from the terminal radio device 30 or a subordinate base station device. Then, the base station apparatus 20 determines whether the upper line is normal or disconnected.

The following describes the operation when the upper line is determined to be normal in step S6. If the upper line is determined to be normal in step S6, the base station apparatus 20 transmits an uplink signal to the headquarters station apparatus 10 or the upper base station apparatus 20 (step S7). Then, the base station device 20 receives the downlink signal returned from the central station device 10 or the upper base station device 20 (step S8).

Next, the base station apparatus 20 determines whether or not to transmit a downlink signal to the lower base station apparatus 20 (step S10). If it is determined in step S10 to transmit to the lower base station apparatus 20, the downlink signal is transmitted to the lower base station without holding time (step S11). On the other hand, if it is determined in step S10 to transmit to the terminal radio device 30 instead of the subordinate base station device 20, the downlink signal is transmitted to the terminal radio device 30 when the transmission suspension time elapses (step S12).

If it is determined in step S6 that the upper line is not normal (that is, the line is disconnected), the base station apparatus 20 holds the uplink signal for the return delay time (step S9). Then, in step S10, it is determined whether or not to transmit the downlink signal obtained by folding back the uplink signal to the lower base station apparatus 20. If it is determined to transmit to the lower base station apparatus 20, no further holding time is required. A downlink signal is transmitted to the lower base station (step S11). On the other hand, if it is determined in step S10 to transmit to the terminal radio apparatus 30 instead of the subordinate base station apparatus 20, the downlink signal is transmitted to the terminal radio apparatus 30 when the transmission suspension time has elapsed in addition to the return delay time ( step S12).

<effect>
The wireless communication system according to Embodiment 1 includes a headquarters station apparatus 10 and a plurality of base station apparatuses 20 connected to the headquarters station apparatus 10 in a tree configuration and communicating with terminal wireless apparatuses 30. A wireless communication system in which a station apparatus 10, a plurality of base station apparatuses 20, and a terminal wireless apparatus 30 communicate in units of frames at a constant cycle, and each of the plurality of base station apparatuses 20 stores a transmission suspension time that stores a transmission suspension time. A time storage unit 253 and a loopback delay time storage unit 254 that stores a loopback delay time are provided. It is a holding time until simultaneous transmission to the terminal radio equipment 30, and the return delay time is the time when the uplink signals transmitted from each of the plurality of base station equipment 20 to the central office equipment 10 are returned by the central office equipment 10. is the time required for the base station apparatus 20 to receive the uplink signal as a downlink signal. , when the time obtained by adding the transmission suspension time to the return delay time has elapsed, the base station apparatus 20 performs return transmission of the downlink signal to the terminal radio apparatus 30 and the line with the headquarters station apparatus 10 is not disconnected. transmits the uplink signal transmitted from the terminal wireless device 30 to the headquarters station device 10, and receives the returned downlink signal at the headquarters station device 10. When the transmission suspension time elapses, the terminal wireless device 30 receives send a downlink signal to

Conventionally, when a base station device 20 whose line with the headquarters station device 10 is disconnected switches to base station return communication, it is possible to maintain multi-station simultaneous transmission with other normal base station devices 20. could not. Therefore, there is a problem that signal interference occurs in the downlink signal, and the terminal radio apparatus 30 cannot receive the signal normally.

In the first embodiment, the base station apparatus 20, which has been disconnected from the central station apparatus 10, suspends signal transmission for a period of time obtained by adding the transmission suspension time to the turn-around delay time. wrap the signal. A normal base station device 20 that is not disconnected from the central station device 10 transmits a downlink signal while suspending signal transmission for the transmission suspension time. As a result, even when the base station device 20 whose line with the headquarters station device 10 is disconnected switches to base station return communication, multiple-station simultaneous transmission is maintained with other normal base station devices 20. It is possible to Therefore, it is possible to suppress the signal interference in the downlink signal, and the terminal radio apparatus 30 can receive the interference-suppressed signal.

Further, in the radio communication system according to Embodiment 1, each of the plurality of base station apparatuses 20 includes a line delay time measurement unit 251 that measures line delay time, a loop delay time measurement unit 252 that measures loop delay time, and , and the line delay time is the time required for transmission of a downlink signal from the headquarters station apparatus to the base station apparatus, and is stored in each of the transmission suspension time storage units 253 of the plurality of base station apparatuses 20. The transmission suspension time is determined based on the timing of the frame that can be transmitted by the base station apparatus 20 with the longest line delay time.

Therefore, each of the plurality of base station apparatuses 20 is provided with a line delay time measurement section 251 and a return delay time measurement section 252, so that all of the plurality of base station apparatuses 20 can obtain the line delay time and the return delay time. becomes possible. In addition, since the transmission suspension time of each base station apparatus 20 is determined based on the timing of the frame that can be transmitted by the base station apparatus 20 with the longest line delay time, all of these base station apparatuses 20 Multi-station simultaneous transmission is possible.

Further, in the radio communication system according to Embodiment 1, the headquarters station apparatus 10 includes a transmission suspension time determination section 132, and the transmission suspension time determination section 132 determines that the line delay time measurement sections 251 of the plurality of base station apparatuses 20 Based on the measured line delay times, the transmission suspension times to be stored in the transmission suspension time storage units 253 of the plurality of base station apparatuses 20 are determined.

Therefore, by determining the transmission suspension time of each base station device 20 in the headquarters station device 10, it is possible to notify each transmission suspension time to each base station device 20. FIG.

In addition, in the wireless communication system according to the first embodiment, the terminal wireless device 30 performs voice communication using the press-to-talk method. In Embodiment 1, even if a certain base station apparatus 20 is disconnected from the headquarters station apparatus and switched to return communication, downlink signal interference with other normal base station apparatuses 20 can be suppressed. Therefore, when voice communication is performed using the press-to-talk method, the terminal radio device 30 can receive high-quality voice signals with suppressed interference.

Further, in the wireless communication system according to the first embodiment, the headquarters station apparatus 10 and the plurality of base station apparatuses 20 operate based on a common synchronization signal, and the synchronization signal is a time pulse transmitted from a GPS satellite. . Therefore, by using the time pulse transmitted from the GPS satellite as a synchronizing signal, it is possible to achieve high-accuracy synchronization between the headquarters station apparatus 10 and the plurality of base station apparatuses 20 .

<Embodiment 2>
In the first embodiment, the state in which the terminal wireless device 30 is conducting a voice call has been described. . This is because the signals transmitted by the normal base station device 20 and the base station device 20 whose line is disconnected may differ, and the signals transmitted from each base station device 20 interfere with each other. .

The second embodiment suppresses signal interference during non-communication. In the second embodiment, the base station apparatus 20 whose line is disconnected from the headquarters station apparatus 10 has a frame format area that affects the content of the downlink signal of the normal base station apparatus 20 when there is no communication. (that is, user channel) transmission is stopped and only the area necessary for frame format synchronization is transmitted.

FIG. 11 is a diagram showing a frame format of a downlink signal transmitted by normal base station apparatus 20. As shown in FIG. As shown in FIG. 11, the frame format transmitted by the normal base station apparatus 20 consists of ramp (R), user channel (USC), synchronization word (SW), and guard (G). Here, a ramp (R) is a power ramp indicating the beginning of a TDMA (Time Division Multiplexing) time slot. A user channel (USC) is an area where the content of communication is entered. A sync word (SW) is an area where a bit pattern for synchronization is entered. A guard (G) is an area in which a guard time for avoiding signal collision is entered.

FIG. 12 is a diagram showing a frame format of a downlink signal transmitted by the base station apparatus 20, to which the line with the headquarters station apparatus 10 is disconnected, when there is no communication. As shown in FIG. 12, the base station apparatus 20 whose line is disconnected transmits a downlink signal in a signal frame format that includes information necessary for synchronization and does not include a user channel (USC) during non-communication. do. That is, as shown in FIG. 12, the downstream signal is transmitted in a frame format that includes guard (G), ramp (R), sync word (SW), and does not include user channel (USC).

<effect>
In the radio communication system according to the second embodiment, the base station device 20, which is disconnected from the central station device 10, contains information necessary for synchronization when the terminal radio device 30 is not talking, and , a signal in a format that does not include a user channel is transmitted to the terminal radio device 20. FIG. Therefore, when there is no communication, it is possible to suppress interference between the downlink signal of the base station apparatus 20 whose line with the headquarters station apparatus 10 is disconnected and the downlink signal of another normal base station apparatus 20. , and it is possible to suppress the occurrence of a deviation in synchronization of the terminal wireless device 30 .

<Embodiment 3>
In Embodiment 1, an example of voice communication is shown in the simultaneous transmission of multiple stations, but simultaneous transmission of multiple stations can be applied to not only voice communication but also notification information. The notification information includes frequency, communication channel, and system control information related to communication services, which are notified from the headquarters station apparatus 10 to the terminal radio apparatus 30 .

FIG.13 is a block diagram showing the configuration of the base station apparatus 20A according to the third embodiment. Base station apparatus 20A further includes broadcast information storage section 29 in addition to base station apparatus 20 of Embodiment 1 (FIG. 3). Since other configurations are the same as those of the base station apparatus 20, description thereof is omitted.

All the base station devices 20A cause the report information storage unit 29 to store the report information for one cycle received from the headquarters station device 10 in a normal state. The notification information storage unit 29 also stores the reception time of the notification information and the reception cycle of the notification information.

Also in the third embodiment, as shown in FIG. 7, the first and third base station apparatuses 201 and 203 are normally connected to the headquarters station apparatus 10, and the second base station apparatus 202 is connected to the headquarters station apparatus. Assume that the connection with the station device 10 is disconnected.

FIG. 14 is a diagram showing transmission timing of notification information of the wireless communication system when the line is disconnected. 14, as in FIG. 6, the central station apparatus 10 and all the base station apparatuses 20A perform signal processing based on 1PPS. The broadcast information is a signal transmitted from the central station apparatus 10 at regular intervals using a plurality of frames.

As shown in FIG. 14, the first and third base station devices 201 and 203 connected to the headquarters station device 10 receive the notification information transmitted from the headquarters station device 10, and then the transmission suspension time elapses. Then, the notification information is transmitted to the terminal radio device 30 .

Further, as shown in FIG. 14, the second base station device 202, which is disconnected from the main station device 10, receives the notification information at the reception time stored in the notification information storage unit 29 and receives the notification information. By referring to the period, the timing of receiving the broadcast information is predicted assuming that the line is normal. Then, the notification information stored in the notification information storage unit 29 is transmitted to the terminal radio device 30 at a timing shifted by the transmission suspension time (66 ms in FIG. 14) from the timing at which the notification information is expected to be received.

As described above, the second base station device 202 whose line is disconnected from the headquarters station device 10 synchronizes with the normal base station devices (first and third base station devices 201 and 203) at the same timing. It is possible to transmit notification information by

<effect>
In the radio communication system according to Embodiment 3, each of the plurality of base station apparatuses 20 further includes a broadcast information storage unit 29, and the headquarters station apparatus 10 periodically sends broadcast information to the plurality of base station apparatuses 20. When each of the plurality of base station apparatuses 20 receives the notification information, it stores the notification information, the reception time of the notification information, and the reception period of the notification information in the notification information storage unit 29, and the transmission suspension time has passed. At this time, the base station device 20, which transmits the notification information to the terminal wireless device 30 and the line with the headquarters station device 10 is disconnected, receives the notification information stored in the notification information storage unit 29 at the reception time and reception time. By referring to the cycle, the notification information stored in the notification information storage unit 29 is transmitted to the terminal wireless device 30 at a timing shifted by the transmission suspension time from the timing at which the notification information is expected to be received.

Therefore, even if the line with the headquarters station apparatus 10 is disconnected, the base station apparatus 20 can continue to transmit the notification information at the same timing as other normal base station apparatuses 20. It is possible.

<Embodiment 4>
In the third embodiment, simultaneous transmission of broadcast information to multiple stations has been described, but the present invention can also be applied to transmission of generation numbers of broadcast information. As a method for avoiding the terminal wireless device 30 from constantly receiving the notification information, the generation of the notification information is managed, the generation number is notified to the terminal wireless device 30, and the terminal wireless device 30 receives the notification information only when the content of the notification information changes. There is a method of making the receiver receive the notification information.

Since the configuration of the base station apparatus in Embodiment 4 is the same as that of base station apparatus 20A in Embodiment 3, it will be described with reference to FIG. In the fourth embodiment, all the base station devices 20A store the generation number of the notification information received from the headquarters station device 10 in the notification information storage unit 29 during normal operation. The notification information storage unit 29 also stores the reception time of the generation number of the notification information and the reception cycle of the generation number of the notification information.

Also in the fourth embodiment, as shown in FIG. 7, the first and third base station apparatuses 201 and 203 are normally connected to the headquarters station apparatus 10, and the second base station apparatus 202 is connected to the headquarters station apparatus. Assume that the connection with the station device 10 is disconnected.

FIG. 15 is a diagram showing the transmission timing of the generation number of broadcast information of the wireless communication system when the line is disconnected. 15, as in FIG. 6, the central station apparatus 10 and all the base station apparatuses 20A perform signal processing based on 1PPS. The generation number of the broadcast information is a signal that is transmitted from the central station device 10 at regular intervals when there is no call.

As shown in FIG. 15, the first and third base station devices 201 and 203 connected to the headquarters station device 10 receive the generation number of the broadcast information transmitted from the headquarters station device 10 and then suspend transmission. When the time elapses, the generation number of the broadcast information is transmitted to the terminal radio device 30. - 特許庁

Further, as shown in FIG. 15, the second base station device 202, which is disconnected from the main station device 10, receives the generation number of the broadcast information stored in the broadcast information storage unit 29 and notifies the broadcast information. By referring to the reception cycle of the information generation application number, the timing of receiving the generation number of the broadcast information when it is assumed that the line is normal is predicted. Then, the generation number of the notification information stored in the notification information storage unit 29 is transferred to the terminal wireless device at a timing shifted by the transmission suspension time (66 ms in FIG. 14) from the timing at which the generation number of the notification information is predicted to be received. 30.

As described above, the second base station device 202 whose line is disconnected from the headquarters station device 10 synchronizes with the normal base station devices (first and third base station devices 201 and 203) at the same timing. It is possible to transmit the generation number of the broadcast information by

<effect>
In the wireless communication system according to the fourth embodiment, the broadcast information is associated with a generation number indicating the generation of the broadcast information, and the headquarters station apparatus 10 periodically sends the generation number to the plurality of base station apparatuses 20. When each of the plurality of base station devices 20 receives the generation number, it stores the generation number, the reception time of the generation number, and the reception cycle of the generation number in the notification information storage unit 29, and the transmission suspension time has elapsed. When the generation number is transmitted to the terminal wireless device 30, the base station device 20, which is disconnected from the main station device, receives the generation number and the reception cycle stored in the notification information storage unit 29. , the generation number stored in the notification information storage unit 29 is transmitted to the terminal wireless device 30 at a timing shifted by the transmission suspension time from the timing at which the generation number is expected to be received.

Therefore, even if the line with the headquarters station device 10 is disconnected, the base station device 20 continues to transmit the generation number of the broadcast information at the same timing as other normal base station devices 20. It is possible to

In addition, within the scope of the invention, each embodiment can be freely combined, and each embodiment can be appropriately modified or omitted.

10 headquarters station device 11 return processing unit 12 control unit 13 downlink transmission timing adjustment unit 131 simultaneous transmission possible time determination unit 132 transmission suspension time determination unit 14 base station communication unit 20, 20A base station device 21 upper station communication unit, 22 uplink communication processing unit, 23 return processing unit, 24 downlink communication processing unit, 25 downlink transmission timing adjustment unit, 251 line delay time measurement unit, 252 return delay time measurement unit, 253 transmission suspension time storage unit, 254 return delay time storage unit 26 control unit 27 lower station communication unit 28 terminal radio device communication unit 29 broadcast information storage unit 201 first base station device 202 second base station device 203 third Base station device, 30 Terminal radio device.

Claims (3)

a headquarters station device, a plurality of base station devices connected in a tree structure to the headquarters station device and operating based on a common synchronization signal , and a terminal radio device capable of wirelessly communicating with the base station device a wireless communication system comprising:
said base station device transmits a downlink signal in a first format including a lamp, a user channel, a synchronization word and a guard to said terminal radio device when there is no call;
Another base station apparatus that performs base station return communication transmits a downlink signal in a second format that includes the synchronization word and does not include the user channel to the terminal radio apparatus when there is no call, and
The terminal radio device receives the downlink signal in the first format and the downlink signal in the second format when there is no call.
wireless communication system. a headquarters station device, a plurality of base station devices connected in a tree structure to the headquarters station device and operating based on a common synchronization signal , and a terminal radio device capable of wirelessly communicating with the base station device The terminal radio device of a radio communication system comprising:
receiving a downlink signal in a first format transmitted from the base station device and a downlink signal in a second format transmitted from another base station device performing base station loopback communication during no call;
the first format includes ramps, user channels, sync words, guards;
the second format includes the sync word and does not include the user channel;
Terminal radio equipment. a headquarters station device, a plurality of base station devices connected in a tree structure to the headquarters station device and operating based on a common synchronization signal , and a terminal radio device capable of wirelessly communicating with the base station device The base station device of a wireless communication system comprising:
switching between normal communication in which the central station device folds back from an uplink signal to a downlink signal and base station loopback communication in which the base station device loops back from an uplink signal to a downlink signal;
In the case of normal communication, transmitting a downlink signal in a first format including a lamp, a user channel, a synchronization word, and a guard to the terminal radio equipment when there is no call;
In the case of base station return communication, when there is no call , a downlink signal in a second format that includes the synchronization word and does not include the user channel is transmitted to the terminal radio device.
Base station equipment.

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