JP6753738B2 - Wireless communication system - Google Patents

Description

The present invention relates to a wireless communication system, and in particular, includes a head office device and a plurality of base station devices that are connected to the head office device in a tree shape and communicate with the terminal wireless device. The present invention relates to a wireless communication system in which a base station device and a terminal wireless device communicate in units of frames at regular intervals.

There is known a wireless communication system in which a plurality of base station devices are connected to the headquarters device in a tree shape, and the headquarters device, the plurality of base station devices, and the terminal radio device communicate in a frame unit of a fixed cycle.

In the conventional technique (see, for example, Patent Documents 1 and 2), in a state where the headquarters device and the base station device are connected, the headquarters device and a plurality of bases are used to adjust the timing in the down direction and the up direction. By measuring the delay time between station devices and setting each base station to 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 be used. On the other hand, multiple stations were transmitting at the same time.

Japanese Unexamined Patent Publication No. 2002-27534 JP-A-2007-166278

In the conventional technology, the line delay time between the headquarters device and each base station device is measured while the headquarters device and a plurality of base station devices are connected, and each base station is measured by the delay time of each line. By suspending transmission on the device, simultaneous transmission of multiple stations was realized.

Therefore, when the base station device whose line with the headquarters device is disconnected performs the base station return communication, the timing of transmitting the downlink signal is different from that of the other base station device. Therefore, the other bases in this base station device. It was not possible to maintain simultaneous multi-station transmission with the station equipment.

Terminal radio located in an area that can receive radio waves from both the base station device connected to the headquarters device (normal base station device) and the base station device with the line disconnected from the headquarters device (return base station device). The device receives downlink signals from two different routes (first and second routes). If the timing of the downlink signal passing through these routes is deviated, the interference of the audio signal occurs, and the terminal wireless device 30 cannot normally receive the signal. 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. The second route is a route that is turned back by the turn-back base station device.

The present invention has been made to solve the above problems, and a base station apparatus in which the line to the headquarters apparatus is disconnected can simultaneously transmit multiple stations together with other normal base station apparatus. The purpose is to provide a wireless communication system.

The wireless communication system according to the present invention includes a head office device and a plurality of base station devices that are connected to the head office device in a tree shape and communicate with the terminal wireless device, and include the head office device and a plurality of bases. A wireless communication system in which a station device and a terminal wireless device communicate in units of frames at a fixed cycle, and each of a plurality of base station devices stores a transmission hold time storage unit that stores a transmission hold time and a return delay time. It is equipped with a return delay time storage unit, and the transmission hold time is the hold time from when each of the plurality of base station devices receives the downlink signal from the headquarters device to when it is simultaneously transmitted to the terminal wireless device. The return delay time is the time required for the uplink signal transmitted from each of the plurality of base station devices to the headquarters device to be returned by the headquarters device and received by the base station device as a downlink signal. When the line between the head office device and the base station device is disconnected, the base station device receives the uplink signal from the terminal wireless device, and when the time elapsed by adding the transmission hold time to the return delay time, the terminal wireless device is contacted. The base station device, which transmits the downlink signal back and does not disconnect the line from the headquarters device, transmits the uplink signal transmitted from the terminal wireless device to the headquarters device and returns it at the headquarters device. When the transmission hold time elapses after receiving the downlink signal, the downlink signal is transmitted to the terminal wireless device.

In the wireless communication system according to the present invention, the base station apparatus whose line with the head office apparatus is disconnected suspends the transmission of the signal for the time obtained by adding the transmission holding time to the return delay time, and the signal from the terminal wireless apparatus. Wrap back. In addition, a normal base station device whose line with the head office device is not disconnected suspends signal transmission for a transmission suspension time and transmits a downlink signal. As a result, even if the base station device whose line with the headquarters device is disconnected is switched to base station return communication, it is possible to maintain simultaneous multi-station transmission with other normal base station devices. It is possible. Therefore, it is possible to suppress signal interference in the downlink signal, and the terminal wireless device can receive the signal in which the interference is suppressed.

It is a schematic diagram which shows the structure of the wireless communication system which concerns on Embodiment 1, and the communication state at the time of normal. It is a block diagram which shows the structure of the head office apparatus which concerns on Embodiment 1. FIG. It is a block diagram which shows the structure of the base station apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the hardware configuration of the head office apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the hardware composition of the base station apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the transmission timing of the downlink signal of the wireless communication system in a normal state which concerns on Embodiment 1. FIG. It is a schematic diagram which shows the structure of the wireless communication system which concerns on Embodiment 1, and the communication state at the time of line disconnection. It is a figure which shows the sequence of the return delay time measurement in the wireless communication system which concerns on Embodiment 1. FIG. It is a figure which shows the transmission timing of the downlink signal of the wireless communication system at the time of line disconnection which concerns on Embodiment 1. FIG. It is a flowchart which shows the operation of the wireless communication system which concerns on Embodiment 1. FIG. It is a figure which shows the frame format which the normal base station apparatus which concerns on Embodiment 2 transmits when there is no call. It is a figure which shows the frame format which the base station apparatus which the line with the head office apparatus which concerns on Embodiment 2 is disconnected transmits in the absence of a call. It is a block diagram which shows the structure of the base station apparatus which concerns on Embodiment 3. It is a figure which shows the transmission timing of the broadcast information of the wireless communication system which concerns on Embodiment 3. It is a figure which shows the transmission timing of the generation number of the broadcast information of the wireless communication system which concerns on Embodiment 4.

<Embodiment 1>
<Composition>
FIG. 1 is a diagram showing a configuration of a wireless communication system according to the first embodiment. As shown in FIG. 1, the wireless communication system according to the first embodiment includes a head office device 10 and first to third base station devices 201, 202, 203. The first to third base station devices 201, 202, and 203 are connected to the headquarters station device 10 in a tree shape. The first to third base station devices 201, 202, 203 communicate with the terminal wireless device 30. In the following, when the first to third base station devices 201, 202, and 203 are not distinguished, they are simply referred to as the base station device 20.

In the wireless communication system according to the first embodiment, the head office device 10, the plurality of base station devices 20, and the terminal wireless device 30 communicate in frame units of a fixed cycle. The wireless communication system in the first embodiment is a system that performs press talk type voice communication.

The head office 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 wireless device 30 via a wireless line to relay voice signals and control the wireless line between the main station device 10 and the terminal wireless device 30.

The area R1 shown in FIG. 1 is an area capable of communicating with the first base station device 201 and not receiving radio wave interference from the second base station device 202. The area R2 shown in FIG. 1 is an area capable of communicating with the second base station device 202 and not receiving radio wave interference from the first base station device 201. The area R3 shown in FIG. 1 is an area capable of communicating with both the first and second base station devices 201 and 202.

The uplink signal transmitted from the terminal wireless device 30 is folded back by the head office device 10 and transmitted as a downlink signal to all the base station devices 20. Here, the uplink signal means a signal transmitted in the order of the terminal wireless device 30, the base station device 20, and the headquarters station device 10. The downlink signal means a signal transmitted in the order of the head office device 10, the base station device 20, and the terminal radio device 30.

It is assumed that the downlink signal from each base station device 20 is transmitted using the same frequency. Further, it is assumed that the uplink communication from the terminal wireless 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 head office device 10 according to the first embodiment. As shown in FIG. 2, the head office device 10 includes a return processing unit 11, a control unit 12, a downlink transmission timing adjustment unit 13, and a base station communication unit 14.

The return processing unit 11 has a function of receiving an uplink signal from the base station device 20 via the base station communication unit 14, returning the signal, and transmitting the signal to a 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 perform communication, and notifies the terminal wireless device via the base station device 20. Further, the control unit 12 controls each unit in the head office device 10.

The downlink transmission timing adjustment unit 13 includes a simultaneous transmission possible time determination unit 131 and a transmission hold time determination unit 132. The simultaneous transmission possible time determination unit 131 determines the time during which a plurality of base station devices 20 can simultaneously transmit in order to realize simultaneous transmission of multiple stations. The transmission hold time determination unit 132 determines the transmission hold time for each of the plurality of base station devices 20. The base station communication unit 14 transmits a signal to the base station device 20 and receives a signal from the base station device 20. Receive.

FIG. 3 is a block diagram showing the configuration of the 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 adjusting unit 25, a control unit 26, and a lower station communication. A unit 27 and a terminal wireless device communication unit 28 are provided.

The host station communication unit 21 receives the signal from the head office device 10 directly or via the host station device 20. Further, the higher-level station communication unit 21 transmits a signal to the main station device 10 or the higher-level base station device 20.

The uplink communication processing unit 22 relays the signal received from the terminal wireless device 30 or the lower base station device 20 to the main station device 10 or the upper base station device 20 at normal times. Further, when the upper line is disconnected, 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, the return processing unit 23 transmits the signal received from the uplink communication processing unit 22 to the downlink communication processing unit 24 when the time obtained by adding the return delay time and the transmission hold time elapses. To do.

Normally, the downlink communication processing unit 24 transmits a signal received from the head office 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 adjusting unit 25 includes a line delay time measuring unit 251, a return delay time measuring unit 252, a transmission holding time storage unit 253, and a return delay time storage unit 254.

The line delay time measuring unit 251 measures the line delay time between the head office device 10 and the base station device 20 in order to realize simultaneous transmission of multiple stations. The return delay time measuring unit 252 measures the line delay time when the signal from the base station device 20 is folded back by the main station device 10 and received by the base station device 20.

The transmission hold time storage unit 253 stores the transmission hold time notified from the head office device 10.

The return delay time storage unit 254 stores the return delay time. The control unit 26 processes and stores the broadcast information received from the head office device 10. Further, 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 wireless device communication unit 28 has a function of transmitting a signal received from each processing unit to the terminal wireless device 30, and has a function of transmitting a signal received from the terminal wireless device 30 to each processing unit.

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

When the processing circuit HW12 is dedicated hardware, the processing circuit HW12 corresponds to, for example, a single circuit, a composite circuit, 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 downlink transmission timing adjusting unit 13 are realized by software, firmware, or a combination of software and firmware. Software and firmware are described as programs and stored in the memory HW13. The processing circuit HW 12 realizes the functions of the return processing unit 11, the control unit 12, and the downlink transmission timing adjusting unit 13 by reading and executing the program stored in the memory HW 13. Further, it can be said that this program causes the computer to execute the procedures and methods of the return processing unit 11, the control unit 12, and the downlink transmission timing adjustment unit 13. Here, the memory HW13 includes non-volatile or volatile semiconductor memories such as RAM, SDRAM, ROM, flash memory, EPROM, and EEPROM, magnetic disks, flexible disks, optical disks, compact disks, mini disks, and DVDs. Etc. are applicable.

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

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

When the processing circuit HW24 is dedicated hardware, the processing circuit HW24 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. ..

When the processing circuit HW24 is a CPU, the functions of the uplink communication processing unit 22, the return processing unit 22, the downlink communication processing unit 24, the downlink transmission timing adjusting unit 25, and the control unit 26 depend on software, firmware, or a combination of software and firmware. It will be realized. Software and firmware are described as programs and stored in the memory HW25. The processing circuit HW24 reads and executes the program stored in the memory HW 25 to perform the functions of the uplink communication processing unit 22, the return processing unit 22, the downlink communication processing unit 24, the downlink transmission timing adjusting unit 25, and the control unit 26. Realize. Further, it can be said that this program causes the computer to execute the procedures and methods of the uplink communication processing unit 22, the return processing unit 22, the downlink communication processing unit 24, the downlink transmission timing adjusting unit 25, and the control unit 26. Here, the memory HW25 includes non-volatile or volatile semiconductor memories such as RAM, SDRAM, ROM, flash memory, EPROM, and EEPROM, magnetic disks, flexible disks, optical disks, compact disks, mini disks, and DVDs. Etc. are applicable.

Some of the functions of the uplink communication processing unit 22, the return processing unit 22, the downlink communication processing unit 24, the downlink transmission timing adjusting unit 25, and the control unit 26 are realized by dedicated hardware, and some are software or firmware. It may be realized by.

<Normal operation>
First, the operation of the wireless communication system under normal conditions will be described. Here, "normal time" means that the line is not disconnected between the head office device 10 and the base station device 20 under its umbrella.

FIG. 6 is a diagram showing the transmission timing of the downlink signal of the wireless communication system in the normal state. The timing in the upper part of FIG. 6 is 1 PPS (1 second pulse) received from a GPS (Global Positioning System) satellite. The head office device 10 and all the base station devices 20 perform signal processing based on 1PPS received from GPS satellites as a synchronization signal. Each of the head office device 10 and all the base station devices 20 includes a synchronization signal receiving unit (not shown), and the synchronization signal receiving unit receives the synchronization signal.

The downlink signal transmitted from the headquarters device 10 is delayed by the signal processing time inside the headquarters device 10 starting from the 1PPS reference. This is defined as the offset time. In the example of FIG. 6, the offset time is 4 ms. In addition, a line delay time occurs as the time until the downlink signal transmitted from the head office device 10 is received by the base station device 20.

In the example of FIG. 6, the line delay times of the first to third base station devices 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 with respect to the third base station apparatus 203 is delayed most. Further, as shown in FIG. 6, the time from the reception of the downlink signal by the third base station device 203 to the next frame that can be transmitted is 30 ms.

The simultaneous transmission possible time is the time from when the head office device 10 transmits the downlink signal to when all the base station devices 20 can simultaneously transmit 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, which has the longest signal arrival delay. That is, the simultaneous transmission possible time includes the offset time (4 ms) inside the head office device 10, the line delay time (86 ms) of the third base station device 203 in which the arrival of the signal is delayed most, and the third base station device 203. Is calculated by adding up the time (30 ms) from the reception of the downlink signal to the next frame that can be transmitted. In the case of FIG. 6, the simultaneous transmission possible time is 120 ms.

A method of measuring the simultaneous transmission time will be described. The head office device 10 transmits a line delay time measurement instruction to all the base station devices 20 (first to third base station devices 201, 202, 203) under its control. This instruction includes the time when the head office device 10 transmits the instruction.

The line delay time measuring unit 251 of each base station device 20 that has received the line delay time measurement instruction responds to the head office device 10 at the time when the instruction is received (downlink signal reception timing). Alternatively, the line delay time measuring unit 251 may calculate the line delay time by subtracting the time when the head office device 10 transmits the instruction from the time when the instruction is received, and may respond to the line delay time.

The head office device 10 that has received the downlink signal reception timing from each of the base station devices 20 under its umbrella calculates the line delay time for each base station device 20. When the base station device 20 under the umbrella responds with the line delay time, the head office device 10 does not need to calculate the line delay time.

Then, the head office device 10 can simultaneously transmit the timing of the frame in which the downlink signal can be transmitted with reference to the base station device 20 (third base station device 203 in the example of FIG. 6) having the largest line delay time. To determine as. In the example of FIG. 6, the simultaneous transmission possible time is 120 ms.

Next, the head office device 10 transmission hold time determination unit 132 calculates the time (transmission hold time) for holding the transmission of the downlink signal after each base station device 20 receives the downlink signal. The transmission hold 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 holding time of the first base station apparatus 201 is 75 ms by the calculation of 120 ms-4 ms-41 ms. The transmission hold time of the second base station device 202 is 50 ms by the calculation of 120 ms-4 ms-66 ms. The transmission hold time of the third base station apparatus 203 is 30 ms by the calculation of 120 ms-4 ms-86 ms.

Then, the head office device 10 notifies the corresponding base station device 20 of the transmission hold time of each base station device 20. When each base station device 20 receives the transmission hold time, the transmission hold time storage unit 253 stores the transmission hold time. In the example of FIG. 6, 75 ms, 50 ms, and 30 ms are stored in the transmission hold time storage units 253 of the first to third base station devices 201, 202, and 203, respectively.

Further, instead of the head office device 10 calculating the transmission hold time, each base station device 20 may calculate the transmission hold time. In this case, the head office device 10 transmits the simultaneous transmission possible time and the offset time to each base station device 20, and each base station device 20 calculates and stores the transmission hold time using the line delay time.

Each base station device 20 under the control of the head office device 10 transmits the downlink signal when the transmission hold time elapses after receiving the downlink signal. As a result, when the simultaneous transmission possible time (120 ms in the example of FIG. 6) elapses starting from 1PPS, the downlink signal is simultaneously transmitted from each base station device 20. By the above operation, synchronization is maintained on the wireless line, and simultaneous transmission of multiple stations becomes possible.

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

In the conventional technique, the line between the first base station device 201 (normal base station device) connected to the headquarters device 10 and the second base station device 202 (normal base station device 10) is disconnected. In the area R3 that receives both radio waves of the return base station apparatus), interference of the downlink signal has occurred.

The terminal radio device 30 located in the area R3 receives downlink signals from two different routes (first and second routes). If the timing of the downlink signal passing through these routes is deviated, the interference of the audio signal occurs, and the terminal wireless device 30 cannot normally receive the signal. Here, the first route is a route that relays in the order of the first base station device 201, the headquarters station device 10, and the first base station device 201. The second route is a route that is turned back by the second base station device 202. The first embodiment solves the above problem.

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

The head office device 10 transmits a return delay time measurement instruction to all the base station devices 20 (first to third base station devices 201, 202, 203) under its control. Upon receiving the return delay time measurement instruction, the first base station device 201 transmits the delay time measurement signal to the head office device 10. When the head office device 10 receives the delay time measurement signal from the first base station device 201, it performs a return process and transmits the delay time measurement signal to the first base station device 201. The return processing requires the signal processing time (offset time) inside the head office device 10.

The return delay time measurement unit 252 of the first base station device 201 that has received the delay time measurement signal uses the time when the first base station device 201 transmits the delay time measurement signal to the headquarters device 10 to return the delay time. 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 device 201 has been described above, the return delay time of the second and third base station devices 202 and 203 is similarly determined and stored in the return delay time storage unit 254. To.

FIG. 9 is a diagram showing the transmission timing of the downlink signal of the wireless communication system when the line is disconnected. In FIG. 9, similarly to FIG. 6, the head office device 10 and all the base station devices 20 perform signal processing with reference to 1PPS. As shown in FIG. 9, when the first and third base station devices 201 and 203 under the headquarters device 10 receive the downlink signal returned by the headquarters device 10 and the transmission hold time elapses. , Send a downlink signal.

Further, the second base station device 202 under 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 is used. The downlink signal is transmitted back to the device 30. As a result, the second base station device 202 whose line is disconnected can transmit signals in synchronization with the normal base station devices (first and third base station devices 201 and 203) at the same timing. It is possible.

FIG. 10 is a flowchart showing the operation of the base station device 20. The base station apparatus 20 executes steps S1 to S4 in advance in a state where the line with the head office apparatus 10 is not disconnected (normal state). That is, the base station device 20 receives the transmission hold time from the main station device 10 and stores it in the transmission hold time storage unit 253 (steps S1 and S2). Further, the base station apparatus 20 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 lower base station device. Then, the base station apparatus 20 determines whether the upper line is normal or disconnected.

In the following, the operation when the upper line is determined to be normal in step S6 will be described. When it is determined in step S6 that the upper line is normal, the base station apparatus 20 transmits an uplink signal to the main station apparatus 10 or the upper base station apparatus 20 (step S7). Then, the base station apparatus 20 receives the downlink signal returned from the main station apparatus 10 or the higher-level base station apparatus 20 (step S8).

Next, the base station apparatus 20 determines whether or not to transmit the downlink signal to the lower base station apparatus 20 (step S10). If it is determined in step S10 that the signal is transmitted 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 that the signal is transmitted to the terminal wireless device 30 instead of the lower base station device 20, the downlink signal is transmitted to the terminal wireless device 30 when the transmission hold time has elapsed (step S12).

When 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, and if it is determined to transmit to the lower base station apparatus 20, there is no further holding time. The downlink signal is transmitted to a lower base station (step S11). On the other hand, if it is determined in step S10 that the signal is transmitted to the terminal wireless device 30 instead of the lower base station device 20, the downlink signal is transmitted to the terminal wireless device 30 when the transmission hold time has elapsed in addition to the return delay time ( Step S12).

<Effect>
The wireless communication system according to the first embodiment includes a head office device 10 and a plurality of base station devices 20 that are connected to the head office device 10 in a tree shape and communicate with the terminal wireless device 30. A wireless communication system in which a station device 10, a plurality of base station devices 20, and a terminal wireless device 30 communicate in a frame unit of a fixed cycle, and each of the plurality of base station devices 20 is a transmission hold that stores a transmission hold time. A time storage unit 253 and a return delay time storage unit 254 for storing the return delay time are provided, and the transmission hold time is set after each of the plurality of base station devices 20 receives a downlink signal from the head office device 10. The hold time until simultaneous transmission to the terminal wireless device 30, and the return delay time is the return signal transmitted from each of the plurality of base station devices 20 to the headquarters device 10 to be returned by the headquarters device 10. It is the time required for the base station device 20 to receive the downlink signal as a downlink signal, and after the base station apparatus 20 whose line with the headquarters station apparatus 10 is disconnected receives the uplink signal from the terminal wireless device 30. , When the time obtained by adding the transmission hold time to the return delay time elapses, the downlink signal is transmitted back to the terminal wireless device 30, and the line to the head office device 10 is not disconnected. Transmits the uplink signal transmitted from the terminal wireless device 30 to the head office device 10, receives the downlink signal returned by the headquarters device 10, and then sends the transmission hold time to the terminal wireless device 30. On the other hand, a downlink signal is transmitted.

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

In the first embodiment, the base station device 20 in which the line with the head office device 10 is disconnected suspends the transmission of the signal for the time obtained by adding the transmission holding time to the return delay time, and the terminal wireless device 30 sends the signal. Wrap the signal. Further, the normal base station apparatus 20 in which the line with the head office apparatus 10 is not disconnected suspends the transmission of the signal for the transmission suspension time and transmits the downlink signal. As a result, even when the base station device 20 whose line with the head office device 10 is disconnected is switched to the base station return communication, the simultaneous transmission of multiple stations with the other normal base station device 20 is maintained. It is possible to do. Therefore, it is possible to suppress signal interference in the downlink signal, and the terminal wireless device 30 can receive the signal in which the interference is suppressed.

Further, in the wireless communication system according to the first embodiment, each of the plurality of base station devices 20 has a line delay time measuring unit 251 for measuring the line delay time and a loopback delay time measuring unit 252 for measuring the loopback delay time. The line delay time is the time required for transmitting a downlink signal from the headquarters device to the base station device, and is stored in each of the transmission hold time storage units 253 of the plurality of base station devices 20. The transmission hold time is determined based on the timing of frames that can be transmitted by the base station apparatus 20 having the largest line delay time.

Therefore, since each of the plurality of base station devices 20 includes the line delay time measuring unit 251 and the return delay time measuring unit 252, the line delay time and the return delay time can be obtained in all of the plurality of base station devices 20. Is possible. Further, since the transmission holding time of each base station device 20 is determined based on the timing of the frame in which the base station device 20 having the largest line delay time can transmit, all of these base station devices 20 have a downlink signal. Simultaneous transmission of multiple stations is possible.

Further, in the wireless communication system according to the first embodiment, the head office device 10 includes a transmission hold time determination unit 132, and the transmission hold time determination unit 132 includes a line delay time measurement unit 251 of a plurality of base station devices 20. Based on the measured line delay time, the transmission hold time stored in the transmission hold time storage unit 253 of the plurality of base station devices 20 is determined.

Therefore, by determining the transmission hold time of each base station device 20 in the head office device 10, it is possible to notify each base station device 20 of each transmission hold time.

Further, in the wireless communication system according to the first embodiment, the terminal wireless device 30 performs voice communication by a press talk method. In the first embodiment, even if the connection of a certain base station device 20 with the main station device is disconnected and the communication is switched to the return communication, the interference of the downlink signal with the other normal base station device 20 It is possible to suppress. Therefore, when performing voice communication by the press talk method, the terminal wireless device 30 can receive a high-quality voice signal in which interference is suppressed.

Further, in the wireless communication system according to the first embodiment, the head office device 10 and the plurality of base station devices 20 operate with reference to 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 synchronization signal, it is possible to synchronize the head office device 10 and the plurality of base station devices 20 with high accuracy.

<Embodiment 2>
In the first embodiment, the state in which the terminal wireless device 30 is making a voice call has been described, but when there is no call, the synchronization of the terminal wireless device 30 located in the area R3 (interference area) may be out of sync. .. This is because the signals transmitted by the normal base station device 20 and the base station device 20 whose line is disconnected may be different, and the signals transmitted from the respective base station devices 20 interfere with each other. ..

The second embodiment suppresses signal interference when there is no call. In the second embodiment, the base station device 20 whose line is disconnected from the head office device 10 is a frame format area that affects the content of the downlink signal of the normal base station device 20 when there is no call. Stop transmitting (ie, user channel) and transmit only the area required for frame format synchronization.

FIG. 11 is a diagram showing a frame format of a downlink signal transmitted by a normal base station apparatus 20. As shown in FIG. 11, the frame format transmitted by the normal base station apparatus 20 is composed of a lamp (R), a user channel (USC), a synchronization word (SW), and a guard (G). Here, the lamp (R) is a power lamp indicating the beginning of a TDMA (time division multiple access) time slot. The user channel (USC) is an area where the content of communication enters. The synchronization word (SW) is an area in which a bit pattern for synchronization is entered. The guard (G) is an area where a guard time for avoiding a signal collision is entered.

FIG. 12 is a diagram showing a frame format of a downlink signal transmitted by the base station device 20 in which the line with the head office device 10 is disconnected when there is no call. As shown in FIG. 12, the base station apparatus 20 in which the 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) when there is no call. To do. That is, as shown in FIG. 12, the downlink signal is transmitted in a frame format including the guard (G), the lamp (R), and the synchronization word (SW) and not including the user channel (USC).

<Effect>
In the wireless communication system according to the second embodiment, the base station device 20 in which the line to and from the head office device 10 is disconnected includes information necessary for synchronization when the terminal wireless device 30 is not talking. , A signal in a format that does not include the user channel is transmitted to the terminal wireless device 20. Therefore, it is possible to suppress interference between the downlink signal of the base station device 20 in which the line with the head office device 10 is disconnected and the downlink signal of another normal base station device 20 during no call. Therefore, it is possible to prevent the terminal wireless device 30 from being out of sync.

<Embodiment 3>
In the first embodiment, an example of voice communication is shown in the simultaneous transmission of multiple stations, but it is possible to apply the simultaneous transmission of multiple stations not only to voice communication but also to broadcast information. The broadcast information is frequency, communication channel, system control information related to communication services, etc., to be notified from the head office device 10 to the terminal radio device 30.

FIG. 13 is a block diagram showing the configuration of the base station device 20A according to the third embodiment. The base station device 20A further includes a notification information storage unit 29 with respect to the base station device 20 (FIG. 3) of the first embodiment. Since other configurations are the same as those of the base station apparatus 20, the description thereof will be omitted.

In the normal state, all the base station devices 20A store the notification information for one cycle received from the head office device 10 in the notification information storage unit 29. In addition, 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 devices 201 and 203 are normally connected to the headquarters station device 10, and the second base station device 202 is the headquarters. It is assumed that the connection with the station device 10 is disconnected.

FIG. 14 is a diagram showing the transmission timing of the broadcast information of the wireless communication system when the line is disconnected. In FIG. 14, similarly to FIG. 6, the head office device 10 and all the base station devices 20A perform signal processing with reference to 1PPS. The broadcast information is a signal transmitted from the head office device 10 using a plurality of frames at regular intervals.

As shown in FIG. 14, the first and third base station devices 201 and 203 connected to the headquarters device 10 have elapsed a transmission hold time after receiving the notification information transmitted from the headquarters device 10. At that time, the notification information is transmitted to the terminal wireless device 30.

Further, as shown in FIG. 14, the second base station device 202, in which the line with the head office device 10 is disconnected, receives the notification information and the notification information stored in the notification information storage unit 29. By referring to the cycle, the timing of receiving the broadcast information assuming that the line is normal is predicted. Then, the broadcast information stored in the broadcast information storage unit 29 is transmitted to the terminal wireless device 30 at a timing shifted by the transmission hold time (66 ms in FIG. 14) from the timing predicted to receive the broadcast information.

As described above, the second base station device 202 whose line is disconnected from the main station device 10 is synchronized 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 notification information.

<Effect>
In the wireless communication system according to the third embodiment, each of the plurality of base station devices 20 further includes a broadcast information storage unit 29, and the head office device 10 periodically transmits broadcast information to the plurality of base station devices 20. Upon receiving the broadcast information, each of the plurality of base station devices 20 stores the broadcast information, the reception time of the broadcast information, and the reception cycle of the broadcast information in the broadcast information storage unit 29, and the transmission hold time has elapsed. The base station device 20 sometimes transmits the notification information to the terminal radio device 30 and the line with the head office device 10 is disconnected, and the base station device 20 receives the notification information stored in the notification information storage unit 29. With reference to the cycle, the broadcast information stored in the broadcast information storage unit 29 is transmitted to the terminal radio device 30 at a timing shifted by the transmission hold time from the timing predicted to receive the broadcast information.

Therefore, the base station apparatus 20 can continuously transmit the broadcast information at the same timing as the other normal base station apparatus 20 even if the line is disconnected from the main station apparatus 10. It is possible.

<Embodiment 4>
In the third embodiment, the simultaneous transmission of the broadcast information to multiple stations has been described, but it can also be applied to the transmission of the generation number of the broadcast information. As a method for avoiding the terminal wireless device 30 from constantly receiving the broadcast information, the terminal wireless device 30 manages the broadcast information for generations, notifies the terminal wireless device 30 of the generation number, and only when the content of the broadcast information changes. There is a method of receiving the notification information.

Since the configuration of the base station apparatus according to the fourth embodiment is the same as that of the base station apparatus 20A according to the third embodiment, 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 head office device 10 in the notification information storage unit 29 in the normal state. In addition, 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 devices 201 and 203 are normally connected to the headquarters station device 10, and the second base station device 202 is the headquarters. It is assumed that the connection with the station device 10 is disconnected.

FIG. 15 is a diagram showing the transmission timing of the generation number of the broadcast information of the wireless communication system when the line is disconnected. Also in FIG. 15, similarly to FIG. 6, the head office device 10 and all the base station devices 20A perform signal processing with reference to 1PPS. The generation number of the broadcast information is a signal transmitted from the head office 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 device 10 receive the generation number of the broadcast information transmitted from the headquarters device 10 and then suspend transmission. When the time has passed, the generation number of the notification information is transmitted to the terminal wireless device 30.

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

As described above, the second base station device 202 whose line is disconnected from the main station device 10 is synchronized 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 notification information.

<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 head office device 10 periodically assigns a generation number to the plurality of base station devices 20. Upon receiving the generation number, each of the plurality of base station devices 20 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 hold time has elapsed. At times, the base station device 20 transmits the generation number to the terminal wireless device 30 and the line with the head office device is disconnected, and the base station device 20 receives the generation number stored in the broadcast information storage unit 29 and the reception cycle. The generation number stored in the broadcast information storage unit 29 is transmitted to the terminal wireless device 30 at a timing shifted by the transmission hold time from the timing predicted to receive the generation number.

Therefore, the base station apparatus 20 continuously transmits the generation number of the broadcast information at the same timing as the other normal base station apparatus 20 even if the line is disconnected from the main station apparatus 10. It is possible to do.

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

10 Headquarters station equipment, 11 Return processing unit, 12 Control unit, 13 Downstream transmission timing adjustment unit, 131 Simultaneous transmission possible time determination unit, 132 Transmission hold time determination unit, 14 Base station communication unit, 20, 20A Base station equipment, 21 High-level station communication unit, 22 uplink communication processing unit, 23 loopback processing unit, 24 downlink communication processing unit, 25 downlink transmission timing adjustment unit, 251 line delay time measuring unit, 252 loopback delay time measuring unit, 253 transmission hold time storage unit, 254 Return delay time storage unit, 26 control unit, 27 lower station communication unit, 28 terminal radio equipment communication unit, 29 notification information storage unit, 201 first base station device, 202 second base station device, 203 third Base station equipment, 30 terminal wireless equipment.

Claims (8)

The head office device and a plurality of base station devices that are connected to the head office device in a tree shape and communicate with the terminal radio device are provided, and the head office device, the plurality of base station devices, and the terminal radio are provided. A wireless communication system in which the device communicates in units of frames with a fixed cycle.
Each of the plurality of base station devices
A transmission hold time storage unit that stores the transmission hold time, and a transmission hold time storage unit,
A wrapping delay time storage unit that stores the wrapping delay time,
With
The transmission hold time is a hold time from when each of the plurality of base station devices receives a downlink signal from the headquarters device and simultaneously transmits the downlink signal to the terminal radio device.
The return delay time is required for the uplink signal transmitted from each of the plurality of base station devices to the headquarters device to be folded back by the headquarters device and received by the base station device as a downlink signal. It's time
The base station device, in which the line with the head office device is disconnected, receives the uplink signal from the terminal radio device, and when the time obtained by adding the transmission hold time to the return delay time elapses, the said The downlink signal is sent back to the terminal wireless device, and the downlink signal is transmitted back.
The base station device whose line to and from the headquarters device is not disconnected transmits an uplink signal transmitted from the terminal radio device to the headquarters device, and transmits a downlink signal returned by the headquarters device. When the transmission hold time elapses after receiving the signal, the downlink signal is transmitted to the terminal wireless device.
Wireless communication system. Each of the plurality of base station devices
A line delay time measuring unit that measures the line delay time,
A folding delay time measuring unit that measures the folding delay time,
Further equipped with,
The line delay time is a time required for transmitting a downlink signal from the headquarters device to the base station device.
The transmission hold time stored in each of the transmission hold time storage units of the plurality of base station devices is determined based on the timing of the frame in which the base station device having the largest line delay time can transmit.
The wireless communication system according to claim 1. The headquarters device includes a transmission hold time determination unit.
The transmission hold time determination unit is stored in the transmission hold time storage unit of the plurality of base station devices based on the line delay time measured by the line delay time measurement unit of the plurality of base station devices. Determine the transmission hold time,
The wireless communication system according to claim 2. The base station device, in which the line to and from the headquarters device is disconnected, transmits a signal in a format that includes information necessary for synchronization and does not include a user channel when the terminal wireless device has no call. Send to the terminal wireless device,
The wireless communication system according to any one of claims 1 to 3. The terminal wireless device performs voice communication by a press talk method.
The wireless communication system according to any one of claims 1 to 4. Each of the plurality of base station devices further includes a broadcast information storage unit.
The headquarters device periodically transmits notification information to the plurality of base station devices,
When each of the plurality of base station devices receives the notification information, the notification information, the reception time of the notification information, and the reception cycle of the notification information are stored in the notification information storage unit, and the transmission holding time is stored. When the elapse has passed, the notification information is transmitted to the terminal wireless device, and the notification information is transmitted.
It is predicted that the base station device whose line with the head office device is disconnected will receive the broadcast information with reference to the reception time and reception cycle of the broadcast information stored in the broadcast information storage unit. The notification information stored in the notification information storage unit is transmitted to the terminal radio device at a timing shifted by the transmission hold time from the above timing.
The wireless communication system according to any one of claims 1 to 5. A generation number indicating the generation of the notification information is associated with the notification information.
The head office device periodically transmits the generation number to the plurality of base station devices.
When each of the plurality of base station devices receives the generation number, the generation number, the reception time of the generation number, and the reception cycle of the generation number are stored in the broadcast information storage unit, and the transmission holding time is stored. When the elapse has passed, the generation number is transmitted to the terminal wireless device, and the generation number is transmitted.
It is predicted that the base station device whose line with the head office device is disconnected will receive the generation number with reference to the reception time and reception cycle of the generation number stored in the broadcast information storage unit. The generation number stored in the broadcast information storage unit is transmitted to the terminal radio device at a timing shifted by the transmission hold time from the above timing.
The wireless communication system according to claim 6. The headquarters device and the plurality of base station devices operate on the basis of a common synchronization signal.
The synchronization signal is a time pulse transmitted from a GPS satellite.
The wireless communication system according to any one of claims 1 to 7.

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