JP7760681B1 - Radio Relay System - Google Patents

Abstract

In a wireless repeating system that performs group communication using paired waves in a semi-duplex system, communication becomes impossible if a repeater or a communication terminal is subjected to jamming radio waves.
[Solution] The repeater 50 has a communication modulation/transmission unit TX01 and a reception/demodulation unit RX01, as well as a reception/demodulation unit RX02 that cyclically scans a group of channels that are always available to search for an available pair of waves, and each communication terminal 60 has a modulation/transmission unit TX11 and a reception/demodulation unit RX11 that has the cyclic scanning function in standby mode. When jamming radio waves are detected in RX01 of the repeater 50, the RX01 changes the setting to the pair of waves that is the farthest away from a non-available pair of waves among the available pairs of waves searched for by RX02, and transmits a channel change request (CCR) from TX01. Each communication terminal 60 receives the CCR during the cyclic scanning process of RX11, and changes the setting of TX11 and RX11 to the transmission/reception pair of waves that corresponds to the receiving channel of the CCR.
[Selected figure] Figure 8

Description

The present invention relates to a wireless repeater system that consists of a wireless repeater and multiple wireless communication terminals that communicate with each other through the repeater using semi-duplex communication, and that automatically changes the currently used paired channel to an available paired channel if there is radio interference with the wireless repeater or the wireless communication terminals.

Traditionally, in group communications using commercial wireless communication devices, which are designated low-power radio stations, wireless repeaters (master stations) have often been installed to expand the communication area, enabling communication with multi-story buildings and separate buildings, and to ensure communication in areas where radio waves are difficult to reach due to obstructions, etc., and to improve call quality, and a group communication network is formed using wireless communication terminals that pass through the wireless repeaters.
In addition, for business radio communication equipment, which is a land mobile service radio station (for work communication) with an antenna power of 1 mW or less, communication between sub-stations via a master station is the basis, and this forms a group communication network similar to that described above.

In these networks, communication between each wireless communication terminal is carried out using a semi-duplex method via a wireless repeater, with paired channels being used for the uplink and downlink waves involved in this communication. The available paired channels are determined according to the type of radio waves and communication method in standards established based on the Radio Law Enforcement Regulations and Radio Equipment Regulations (see Non-Patent Documents 1 and 2 below). If the wireless repeater and each wireless communication terminal are specified low-power radio stations, the 27 pairs of paired channels shown in Figure 3 are available for use.

Here, it is assumed that the group communication network has a schematic configuration consisting of a wireless repeater 100 and two wireless communication terminals 201 and 202 as shown in FIG.
The wireless repeater 100 and each wireless communication terminal 201, 202 are in a state of using a paired channel with channel number CH1, and the L band group side and H band group side channels of the paired channel are set in an inverse relationship for transmission and reception in the wireless repeater 100 and each wireless communication terminal 201, 202. Specifically, the receiver/demodulator RX01 of the wireless repeater 100 is set to the H band group side channel with channel number CH1, and the modulator/transmitter TX01 is set to the L band group side channel with the same channel number, and the receiver/demodulator RX11, RX21 of each wireless communication terminal 201, 202 are set to the L band group side channel with channel number CH1, and the modulator/transmitter TX11, TX21 are set to the H band group side channel with the same channel number.
The group identification information of this group communication network is the code "01", and this code is always included in the signal transmitted during communication, and the code is detected and confirmed during reception.

Therefore, when wireless communication terminal 201 calls wireless communication terminal 202 from the standby state of Figure 20 to communicate, as shown in Figure 21, the upstream wave from wireless communication terminal 201 to wireless repeater 100 will be a channel on the H band group side of channel number CH1, and the downstream wave will be a channel on the L band group side of the same channel number.
Conversely, the same channel usage conditions naturally apply when wireless communication terminal 202 calls wireless communication terminal 201, and wireless communication terminals 201 and 202 can intermittently perform communication using semi-duplex transmission while alternating between transmission and reception.

However, if another communication network begins operation in a location close to the operating area of the group communication network, and a wireless communication terminal 301 (group identification information is code "02") outside the group communicates using channel number CH1 during the standby state between communications, as shown in Figure 22, the wireless repeater 100 will be occupied, and communication between each wireless communication terminal 201, 202 (group identification information is code "01") within the network will become impossible.
The cause of this communication failure is not limited to radio waves from wireless communication terminal 301 outside the group as described above, but communication failure can also occur when there is a strong noise source nearby.

In this case, group communication can be resumed by waiting until the jamming radio waves on channel number CH1 end, but there is no telling when the jamming radio waves will occur again, so stable communication cannot be expected as long as the pair channel of channel number CH1 is used.
Therefore, the best solution is to change the current paired channel used in the group communication network to another available paired channel.

To address this problem, Patent Document 1 below proposes a repeater device and a communication terminal that maintains a radio relay function even when communication becomes impossible due to jamming radio waves, fading, or the like.
This repeater device is equipped with a control channel repeater and multiple communication channel repeaters, which are units that function as repeaters at their respective set transmission and reception frequencies. However, in the case of the specified low-power radio station, the so-called control channel here is assumed to correspond to the frequency control channel specially provided as channel number 19 in addition to the 27 paired channels shown in Figure 3.
On the other hand, each communication terminal that communicates via a repeater device records transmission failure information and/or transmission retransmission count information (hereinafter referred to as "transmission failure information") indicating that the repeater device did not respond when a call was made to the repeater device via the control channel, and adds the transmission failure information to the signal sent to the repeater device via the control channel and transmits it.

The repeater device is equipped with functional means including a control channel status detection means for recording transmission failure information received from the communication terminal via the control channel, a means for comparing the transmission failure information with preset threshold information, an open communication channel detection means for detecting whether the communication channel repeater is open or closed, a control channel switching information generation means for generating information to switch an open communication channel repeater to a control channel repeater when the transmission failure information exceeds the threshold, and a repeater switching means for transmitting the generated control channel switching information to the communication terminal and switching the corresponding communication channel repeater to the control channel repeater based on the control channel switching information, thereby allowing a communication channel repeater with better communication conditions to take over the control channel repeater's functions when the communication conditions of the control channel repeater deteriorate.

Therefore, the proposal in Patent Document 1 below is to have an idle communication channel repeater take over the function of the control channel repeater when jamming signals or the like occur on the control channel and the control channel repeater stops functioning. However, paragraph [0007] states, "Even with regard to a communication channel repeater, if the communication quality deteriorates, it is possible to maintain normal relay function by using a normal control channel repeater or control channel as the communication channel." This suggests that even when jamming signals or the like occur on a communication channel, the communication channel repeater can be switched to another communication channel repeater.

JP 2009-267685 A

Association of Radio Industries and Businesses, "Specific Low-Power Radio Stations/Radio Equipment for Radio Telephones/Standard Specifications", RCR STD-20 Version 5.1, revised October 29, 2021 Association of Radio Industries and Businesses, "Radio Equipment/Standard for Land Mobile Radio Stations with Antenna Power of 1mW or Less (Work Notification Required)", RCR STD-31 Version 4.0, revised September 28, 2020

As mentioned above, in the proposal of Patent Document 1, in the case of a repeater device where radio interference or the like occurs on a control channel, the function of the control channel repeater is taken over by a communication channel repeater. Also, although not specifically disclosed, if radio interference or the like occurs on a communication channel, the function is transferred from the communication channel repeater to another communication channel repeater or control channel repeater.

However, the repeater device is equipped with a channel repeater (a control channel repeater and multiple communication channel repeaters) as a unit for each channel, and each channel repeater is equipped with a receiving/demodulating unit and a modulating/transmitting unit, each of which has a transmitting/receiving frequency (a paired channel in the case of a specific low-power radio station) set thereto.
Therefore, if a repeater device were to be able to handle n pairs of channels, it would have to incorporate n+1 receiver/demodulator units and modulator/transmitter units, including a control channel, which would naturally make it an expensive device, and in the case of a semi-duplex radio relay system, there would be many unused communication channel repeaters, resulting in extremely poor utilization efficiency.

In addition, in the repeater device, if interference such as radio waves occurs on a communication channel during relay operation, it is possible to switch from the communication channel repeater to another communication channel repeater, but when notifying the communication terminal of information related to the change in communication channel, a control channel repeater will be used.
In this case, since the control channel is a channel for sending and receiving information for the purpose of frequency control, it tends to be used more frequently than other communication channels, and therefore if the same type of communication network is operating in a nearby area, there is a high possibility that it will remain busy and unavailable for a long period of time.

Furthermore, if jamming signals or the like occur at one communication channel repeater and the relay operation is switched to an available communication channel repeater, if multiple communication channel repeaters are installed, the available communication channel detection means may detect multiple available communication channel repeaters. However, even if a communication channel is considered available, radio wave interference may occur if a communication channel of an adjacent frequency is being used.

The present invention was created in consideration of the above-mentioned problems. In a wireless communication system consisting of a wireless repeater and multiple wireless communication terminals, in which each wireless communication terminal uses paired channels for uplink and downlink waves to conduct group communication via the wireless repeater in semi-duplex mode, the object of the present invention is to rationally realize a function that automatically changes the paired channel currently in use to another available paired channel when the wireless repeater or wireless communication terminal detects and confirms that there is interference with the paired channel in use, using a relatively simple configuration and without using a control channel.

The first invention is a wireless relay system comprising a wireless repeater and a plurality of wireless communication terminals constituting a group, in which one paired channel is selected from a group of two channels (hereinafter referred to as "paired channels") that are paired waves that can be used for uplink and downlink waves for communication between the wireless repeater and each wireless communication terminal in the standard established based on the Radio Law Enforcement Regulations and the Radio Equipment Regulations, and performs group communication between the wireless communication terminals using a semi-duplex method. The wireless repeater comprises a receiving and demodulating unit A, a receiving and demodulating unit B, a modulating and transmitting unit C, and a control unit that controls them, and the receiving and demodulating unit A and the modulating and transmitting unit C are set to the one paired channel, while the receiving and demodulating unit B controls the receiving and demodulating unit C. The receiver/demodulator A cyclically scans a group of channels that can be used as receiving channels and searches for an available channel, and in the standby/receiving mode, the receiver/demodulator A and the receiver/demodulator B are turned on and the modulator/transmitter C is turned off, and when group identification information relating to the group is detected and confirmed from the demodulated signal of the receiver/demodulator A, the mode switches to a repeater mode, and in the repeater mode, the modulator/transmitter C is turned on and the carrier wave of the transmission channel is modulated with the demodulated signal output by the receiver/demodulator A and transmitted, and in addition, when the receiver/demodulator A receives radio waves of a certain field strength or more for a predetermined period of time in which the group identification information cannot be detected and confirmed from the demodulated signal, the mode switches to a repeater mode. In this case, the set pair channel of the reception demodulation unit A and the modulation transmission unit C is changed to the pair channel related to the free channel searched by the reception demodulation unit B, and the modulation transmission unit C is turned on to transmit the group identification information and the channel change request information, and each of the wireless communication terminals is provided with a reception demodulation unit D, a modulation transmission unit E and a control unit for controlling them, and the pair channel set in the reception demodulation unit D and the modulation transmission unit E on the wireless repeater side is set in an inverse relationship for transmission and reception, while in a standby mode, the reception demodulation unit D cyclically scans a group of channels that can be used as reception channels, and in a reception .... This wireless relay system is characterized in that the receiving and demodulating unit D is set to the ON state and the modulating and transmitting unit E is set to the OFF state, and the demodulated signal output by the receiving and demodulating unit D is played back as audio; in transmission mode, the receiving and demodulating unit D is set to the OFF state and the modulating and transmitting unit E is set to the ON state, and the carrier wave of the transmission channel of the modulating and transmitting unit E is modulated with the input audio signal and transmitted; and in standby mode, when the receiving and demodulating unit D receives the group identification information and the channel change request information sent by the wireless repeater during its cyclic scanning process, the receiving channel and its corresponding paired channel are set to the receiving and demodulating unit D and the modulating and transmitting unit E, respectively.

The first invention relates to a radio repeating system for automatically changing a currently used channel of a group communication network when a radio repeater receives jamming radio waves.
Jamming radio waves are recognized when group identification information cannot be detected or confirmed from the demodulated signal of the receiving and demodulating unit A, the radio waves have a certain field strength or above, and reception continues for a predetermined period of time or more. Jamming radio waves are recognized when radio waves from wireless communication terminals that do not belong to the group or other noise sources are at a level that interferes with voice calls in group communication and continue for a certain period of time.
In this invention, the wireless repeater is equipped with a receiving and demodulating unit A for signal reception and a receiving and demodulating unit B for channel cyclic scanning, while the receiving and demodulating unit D of each wireless communication terminal serves both as a signal receiving unit and a channel cyclic scanning unit.
In the radio repeater, the receiver/demodulator B performs a cyclic scanning operation in the standby/receive mode to search for an available pair of channels from among the channel group that can be used as a receiving channel for the receiver/demodulator A.
In each wireless communication terminal, the cyclic scanning operation of the receiving and demodulating section D in the standby mode makes it possible to receive information transmission radio waves from the wireless repeater that cannot be received on the currently set channel when the wireless repeater is subjected to jamming radio waves, and in the receiving mode, normal radio wave reception and demodulation are performed on the currently set channel.
In the wireless repeater, when the jamming radio waves are detected at the receiving and demodulating unit A, the receiving and demodulating unit B changes the setting of the free pair channel that it has searched for in advance to the receiving and demodulating unit A and the modulating and transmitting unit C, and the modulating and transmitting unit C modulates and transmits the group identification information and channel change request information through the free channel.Meanwhile, on the side of each wireless communication terminal, the receiving and demodulating unit D in standby mode receives and demodulates the group identification information and channel change request information from the wireless repeater during its cyclic scanning process, and changes the setting of the pair channel related to that receiving channel to the receiving and demodulating unit D and the modulating and transmitting unit E.
In this case, each channel that is changed to the receiving/demodulating unit A and modulating/transmitting unit C on the wireless repeater side and each channel that is changed to the receiving/demodulating unit D and modulating/transmitting unit E on each wireless communication terminal side are naturally the same free pair channels, but the channels have an inverse relationship for transmission and reception on the wireless repeater side and each wireless communication terminal side.
As a result, according to the wireless repeater system of the first aspect of the present invention, when a wireless repeater is subjected to jamming radio waves, the paired channel used for group communication can be automatically changed to another available paired channel, thereby enabling semi-duplex wireless communication in good condition with a high S/N ratio, free from the influence of jamming radio waves.

In the wireless repeater of the wireless communication system according to the first aspect of the present invention, if the receiver/demodulator A receives radio waves of a certain field strength or above for a predetermined period of time, from which the group identification information cannot be confirmed in the demodulated signal, and if multiple free pair channels are detected during a circular scanning process by the receiver/demodulator B immediately before the reception for that predetermined period of time is detected, it is desirable to change the setting of the receiver/demodulator A and the modulator/transmitter C to the free pair channel whose frequency is the greatest difference from a non-free pair channel, and to control the modulator/transmitter C to transmit the group identification information and channel change request information.

The paired channels are determined by the standards of the radio equipment of various radio stations, and in each standard, a large number of usable paired channels are prepared in ascending order at predetermined frequency intervals.
Therefore, although it depends on the conditions such as the installation location of the radio repeater, in the process of one round of scanning in the receiving and demodulating section B, many empty pair channels are often detected.
On the other hand, for example, the frequency interval between each pair of channels in the standard specification in the above-mentioned Non-Patent Document 1 is 12.5 kHz for channel numbers 1 to 18 and 25.0 kHz for channel numbers 32 to 40, as shown in Figure 3, and it is assumed that interference will not occur between paired channels with different channel numbers. However, in cases where a wireless communication system of another group in a nearby area is operating using a channel with an adjacent channel number, where there is a strong noise source such as a microwave oven in a nearby restaurant, where an illegal wireless station or the like is operating at a nearby frequency, or where abnormal radio wave propagation occurs, radio wave interference may occur and disrupt voice communication even if the channel numbers are different.
Therefore, in the wireless repeater according to the first aspect of the invention, if the receiver-demodulator B detects a plurality of free pair channels during one round of scanning immediately before the receiver-demodulator A detects reception of jamming radio waves, the receiver-demodulator B selects from among those free pair channels the free pair channel with the greatest frequency separation from a non-free pair channel (including the currently set pair channel) and changes the setting to the receiver-demodulator A and the modulator-transmitter C, thereby selecting a free pair channel that is as free as possible from the influence of radio wave interference.
The wireless repeater then causes the modulation transmission section C to transmit the group identification information and the channel change request information through the selected free channel, and changes the transmission and reception channel of each wireless communication terminal to the free channel.
Therefore, the influence of jamming radio waves can be more effectively eliminated, and half-duplex radio communication with a high S/N ratio can be realized without radio interference.

Furthermore, the wireless repeater of the wireless communication system according to the first aspect of the present invention selects an available pair channel from the available pair channels taking into consideration the frequency separation from the non-available pair channel, as described above, and changes the settings for the receiver-demodulator A and the modulator-transmitter C. Furthermore, if it is necessary to perform carrier sensing using the receiver-demodulator A prior to the transmission operation of the modulator-transmitter C, it is desirable to control the selection of available pair channels in descending order of frequency separation from the non-available pair channel to perform carrier sensing.

In the radio repeater, except for those with a transmitting antenna power of 1 mW or less, carrier sense must be performed prior to transmission operation. However, since the receiving and demodulating unit B performs carrier sense on the vacant pair channel detected in a single circular scan just before detecting reception of jamming radio waves, it should be in an idle state in most cases.
However, in a congested network environment, even in the short time before carrier sense is performed, the carrier sense result may show a busy state for reasons such as another group starting to use the vacant channel that is the target of carrier sense.
Taking such circumstances into consideration, in this wireless repeater, when the carrier sense result indicates that transmission is not possible, the selection criteria for the next available pair channel to be subjected to carrier sense are set in descending order of the degree of frequency separation from the currently set pair channel, so that an available pair channel that is as unlikely to be affected by jamming radio waves as possible is selected.

The second invention is a wireless repeater system comprising a wireless repeater and a plurality of wireless communication terminals constituting a group, which selects one paired channel from a group of two channels (hereinafter referred to as "paired channels") that are paired waves usable for uplink and downlink waves for communication between the wireless repeater and each wireless communication terminal in the standard established based on the Radio Law Enforcement Regulations and the Radio Equipment Regulations, and performs group communication between the wireless communication terminals using a semi-duplex method. The wireless repeater comprises a receiver/demodulator A, a receiver/demodulator B, a modulator/transmitter C, and a controller for controlling them. The receiver/demodulator A and the modulator/transmitter C are set to the one paired channel, while the receiver/demodulator B cyclically scans a group of channels that can be used as a receiving channel for the receiver/demodulator A. In a standby/receive mode, the receiver/demodulator A and the receiving and demodulating unit B is in an ON state, the modulating and transmitting unit C is in an OFF state, and when group identification information relating to the group is detected and confirmed from the demodulated signal of the receiving and demodulating unit A, the mode is switched to a repeating mode, and in the repeating mode, the modulating and transmitting unit C is in an ON state, and a carrier wave of a transmission channel is modulated with the demodulated signal output by the receiving and demodulating unit A and transmitted, and in addition, in the standby and receiving mode, when the receiving and demodulating unit B receives the group identification information and channel change request information transmitted by any of the wireless communication terminals during the cyclic scanning process, the receiving channel and the channel that is in a pair channel relationship with it are set to the receiving and demodulating unit A and the modulating and transmitting unit C, respectively, and the group identification information and the channel change request information are transmitted from the modulating and transmitting unit C. and each wireless communication terminal comprises a receiving and demodulating unit D, a modulating and transmitting unit E and a control unit for controlling them, and the pair channels set in the receiving and demodulating unit A and the modulating and transmitting unit C on the wireless repeater side are set in the receiving and demodulating unit D and the modulating and transmitting unit E in an inverse relationship for transmission and reception, while in a standby mode, the receiving and demodulating unit D cyclically scans a group of channels that can be used as receiving channels and searches for an available channel, and in a receiving mode, the receiving and demodulating unit D is in an ON state and the modulating and transmitting unit E is in an OFF state, and the demodulated signal output by the receiving and demodulating unit D is reproduced as audio, and in a transmitting mode, the receiving and demodulating unit D is in an OFF state and the modulating and transmitting unit E is in an ON state, and the carrier wave of the transmission channel of the modulating and transmitting unit E is modulated with an input audio signal and transmitted, and in addition, In the standby mode, if the receiver/demodulator D receives radio waves of a certain field strength or higher for a predetermined period of time or longer, and the group identification information cannot be detected or confirmed from the demodulated signal, the set pair channel of the receiver/demodulator D and the modulator/transmitter E is changed to the pair channel related to the available channel searched for by the receiver/demodulator D, and the modulator/transmitter E is turned on to transmit the group identification information and the channel change request information. Meanwhile, if the receiver/demodulator D receives the group identification information and the channel change request information transmitted by the wireless repeater during its cyclic scanning process, the receiver/demodulator D and the modulator/transmitter E are set to the receiving channel and the channel that is paired with it, respectively.

The second invention relates to a wireless repeating system for automatically changing the channel used in a group communication network when a wireless communication terminal side, not a wireless repeater, receives jamming radio waves.
In this invention, as in the first invention, the wireless repeater has a receiving and demodulating unit A, a receiving and demodulating unit B, and a modulating and transmitting unit C, and each wireless communication terminal has a receiving and demodulating unit D and a modulating and transmitting unit E.
However, in the case of this second invention, the receiving and demodulating unit D has not only the function of cyclically scanning the channel group as in the first invention, but also the function of searching for an available channel, and the reception of jamming radio waves by the receiving and demodulating unit D of any one of the wireless communication terminals serves as a trigger, and the wireless communication terminal sets the available pair channel searched for by the receiving and demodulating unit D in the receiving and demodulating unit D and the modulating and transmitting unit F, and transmits group identification information and channel change request information.
On the other hand, the wireless repeater is responsible for propagating the channel change request to wireless communication terminals other than the one wireless communication terminal, and when it receives group identification information and channel change request information during the cyclic scanning process of the receiving and demodulating unit B, it changes and sets the pair channel related to that receiving channel to the receiving and demodulating unit A and the modulating and transmitting unit C, and transmits the group identification information and channel change request information from the modulating and transmitting unit C.
Thereafter, when each wireless communication terminal receives group identification information and channel change request information from the wireless repeater during the cyclic scanning process of the receiving and demodulating unit D, the receiving channel and the channel that is in a pair channel relationship with it are set in the receiving and demodulating unit D and the modulating and transmitting unit E, respectively, as in the case of the first invention.
As a result, the radio repeater and each radio communication terminal can automatically change the paired channel used for group communication from the state where there is jamming radio waves to another free paired channel, and semi-duplex radio communication becomes possible in a good state with a high S/N ratio.
In addition, the group identification information and channel change request information from the wireless repeater will also be received by the receiving and demodulating unit D in a wireless communication terminal that has already received jamming radio waves and has its receiving and demodulating unit D and modulating and transmitting unit E set to an available pair channel.
In this case, the wireless communication terminal may also reset a vacant pair channel, but this can be ignored since direct reception is performed by the reception/demodulation unit D.

In each wireless communication terminal of the wireless communication system according to the second aspect of the present invention, if the receiver/demodulator unit D receives radio waves of a certain field strength or above for a predetermined period of time or longer, from which the group identification information cannot be confirmed from the demodulated signal, and if multiple free pair channels are detected during a circular scanning process by the receiver/demodulator unit E immediately before the reception for that predetermined period of time or longer is detected, it is desirable to change the setting of the receiver/demodulator unit D and the modulator/transmitter unit E to the free pair channel whose frequency is the greatest difference from a non-free pair channel, and to control the modulator/transmitter unit E to transmit the group identification information and channel change request information.

Furthermore, in the wireless communication terminal of the wireless communication system according to the second aspect of the present invention, when carrier sensing is performed using the receiver-demodulator unit D prior to the transmission operation of the modulator-transmitter unit E, it is desirable to control the selection of available pair channels in descending order of frequency separation from non-available pair channels to perform carrier sensing.

These methods for selecting available paired channels involve the same control as when the wireless repeater in the first invention receives jamming signals, and they more effectively eliminate the effects of jamming signals while achieving half-duplex wireless communication with a high S/N ratio and no radio interference.

This invention relates to a wireless repeater system comprising a wireless repeater and multiple wireless communication terminals constituting a group. The system selects one paired channel from a group of paired channels available for uplink and downlink communications between the wireless repeater and each wireless communication terminal in accordance with standards established based on the Radio Law Enforcement Regulations and the Radio Equipment Regulations, and performs group communications between the wireless communication terminals using a semi-duplex method. When the wireless repeater or wireless communication terminal is subjected to jamming signals, the system selects a paired channel from multiple available paired channels previously searched for by cyclic scanning of the paired channel group, and replaces the currently configured paired channel with the currently configured paired channel. This more effectively eliminates the effects of the jamming signals, achieving semi-duplex wireless communications with a high S/N ratio and no radio interference. Furthermore, while the frequency band of jamming signals may be wide depending on the source, more desirable results can be achieved by selecting from the multiple available paired channels the available paired channel with the greatest frequency separation from the non-available paired channels (including the currently configured paired channel that is subjected to jamming signals).

FIG. 2 is a functional block diagram of a wireless repeater applied to the embodiment of the wireless repeating system of the present invention. 1 is a functional block diagram of a wireless communication terminal applied to an embodiment of the wireless relay system of the present invention. FIG. 10 is a table showing paired channel groups (27 pairs in total shown in Tables 3-2 and 3-4 of the above-mentioned Non-Patent Document 1) used in the wireless relay system of the embodiment. FIG. 2 is a diagram illustrating a communication frame format used in the wireless relay system according to the embodiment. FIG. 2 is a diagram of a wireless relay network according to the first embodiment (in standby mode at CH1); FIG. 2 is a diagram of a wireless relay network according to the first embodiment (communication state in CH1); 1 is a diagram showing a wireless relay network according to the first embodiment (a state in which jamming radio waves are generated at a wireless repeater); 1 is a diagram of a wireless relay network according to a first embodiment (in a state in which a channel change request is transmitted from a wireless relay to each wireless communication terminal); 4 is an operation flowchart of the wireless repeater according to the first embodiment. 4 is an operation flowchart of each wireless communication terminal in the first embodiment. FIG. 2 is a diagram of a wireless relay network according to the first embodiment (standby state after channel change settings are made in the wireless relay device and each wireless communication terminal); FIG. 1 is a diagram of a wireless relay network according to the first embodiment (communication state in CH2); FIG. 10 is a diagram of a wireless relay network according to a second embodiment (a state in which radio interference occurs to a wireless communication terminal); FIG. 10 is a diagram of a wireless relay network according to a second embodiment (in a state where a channel change request is transmitted from a wireless communication terminal to a wireless repeater); 10 is a flowchart illustrating the operation of each wireless communication terminal in the second embodiment. 10 is an operation flowchart of a wireless repeater according to the second embodiment. FIG. 10 is a diagram of a wireless relay network according to a second embodiment (in a state in which a channel change request is transmitted from a wireless relay to each wireless communication terminal); FIG. 10 is a diagram of a wireless relay network according to a second embodiment (in standby mode on CH2); FIG. 10 is a diagram of a wireless relay network according to the second embodiment (communication state in CH2); FIG. 1 is a diagram of a wireless relay network according to the prior art (standby state on CH1). FIG. 1 is a diagram of a wireless relay network according to the prior art (communication status at CH1). FIG. 1 is a diagram of a wireless relay network according to the prior art (a state in which radio interference occurs to a wireless repeater);

An embodiment of the wireless repeater system of the present invention will be described in detail below using Figures 1 to 19. However, in this embodiment, the wireless repeater and wireless communication terminal conform to the specified low-power radio station/radio telephone radio equipment described in Non-Patent Document 1 above.

<Configuration of wireless repeater>
The wireless repeater 50 according to the embodiment has the configuration shown in FIG.
In the figure, 11 is a receiving antenna, 12 is an amplifier, RX01 and RX02 are receiving and demodulating units, 13 is a signal switching unit, TX01 is a modulation and transmitting unit, 14 is an amplifier, 15 is a transmitting antenna, 16 is a system control unit, 17 is an operation unit, and 18 are various indicator lamps, and the operation of the entire wireless repeater 50 is controlled by the system control unit 16.
The receiving demodulation unit RX01 and the modulating/transmitting unit TX01 are controlled and set to the uplink and downlink channels, respectively. The receiving demodulation unit RX01 demodulates the signal of the set channel from the radio wave signal received at the receiving antenna 11 and outputs the signal to the modulating/transmitting unit TX01. Meanwhile, the modulating/transmitting unit TX01 modulates the carrier signal of the set channel with the demodulated signal input from the receiving demodulation unit RX01, power amplifies the modulated signal, and transmits it as radio waves from the transmitting antenna 15.

Here, each channel set in the receiver/demodulator RX01 and modulator/transmitter TX01 has a paired channel relationship corresponding to one of the channel numbers in Figure 3, and in each of the embodiments below, the H-band group channel is set in the receiver/demodulator RX01, and the L-band group channel is set in the modulator/transmitter TX01. Therefore, the wireless repeater 50 performs relay communication using paired channels, with the upstream wave set to the H-band group channel and the downstream wave set to the L-band group channel.

On the other hand, the receiving and demodulating unit RX02 is controlled so as to constantly cyclically scan all channels on the H band group side (the same band side as the receiving and demodulating unit RX01) in FIG.
The purpose of using the cyclic scanning function of the receiver/demodulator RX02 differs between the following embodiments 1 and 2. In embodiment 1, the function is used to check for available paired channels during the cyclic scanning of the H band group, and the system control unit 53 updates and stores this information in its built-in memory. In embodiment 2, the function is used to receive group identification information and channel change request signals transmitted from the wireless communication terminal 60 on a channel (a changed/set channel) different from the set channel of the receiver/demodulator RX01.

The operation unit 17 can be used to turn the power on/off, select group communication mode, select available paired channels, and operate buttons for other setting information. Various indicator lamps light up/blink/go off to indicate the mode setting status and the battery (not shown) consumption status, but these are also managed and controlled by the system control unit 16.

<Configuration of wireless communication terminal>
The wireless communication terminals 60a, 60b, and 60c according to the embodiment have the configuration shown in FIG.
In the figure, 20 is a transmitting/receiving antenna, 21 is an antenna switching unit, 22 is an amplifier, RX11 is a receiving/demodulating unit, 23 is an amplifier, 24 is a speaker (or earphone), 25 is a microphone, 26 is an amplifier, TX11 is a modulating transmitter, 27 is an amplifier, 28 is a system control unit, 29 is an operation unit, and 30 is a liquid crystal display unit, and the operation of the entire wireless communication terminals 60a, 60b, and 60c is controlled by the system control unit 28.

In the receiving system of the wireless communication terminals 60a, 60b, and 60c, the radio wave signal received by the receiving antenna 20 is input from the antenna switching unit 21 through the amplifier 22 to the receiving demodulation unit RX11, which demodulates the signal related to the set channel, and the demodulated signal is amplified by the amplifier 23 and output as sound from the speaker 24.
In this receiving mode, a pair channel is set for the receiving demodulation unit RX11 and the modulation transmission unit TX11, but these channels have an inverse relationship for transmission and reception to the pair channel set for the receiving demodulation unit RX01 and the modulation transmission unit TX01 on the wireless repeater 50 side, and in each of the following embodiments, a channel on the L band group side is set for the receiving demodulation unit RX11, and a channel on the H band group side is set for the modulation transmission unit TX11.

On the other hand, in the standby mode, the receiving and demodulating section RX11 is controlled to cyclically scan all the channels on the L band group side in FIG.
The purpose of using the cyclic scanning function of this receiving and demodulating unit RX11 differs between the following embodiments 1 and 2. In embodiment 1, it is used to receive group identification information and a channel change request signal transmitted from the wireless repeater 50 on a changed channel that is different from the channel set in the previous communication. In embodiment 2, in addition to its purpose, it is also used to check for available paired channels by cyclic scanning of the H band group, and to have the system control unit 67 update and store the scanning information in its built-in memory.

In the transmission system of wireless communication terminals 60a, 60b, and 60c, the audio signal input from microphone 25 is amplified by amplifier 26, and modulation transmitter TX11 modulates the carrier signal of the set channel with the amplified audio signal. The modulated signal is then power-amplified by amplifier 27 and emitted as radio waves from transmitting antenna 20 via antenna switching unit 21.

The antenna switching unit 21 must be switched depending on whether the transmission or reception mode is changed, and the power can be turned on/off, various communication modes can be selected, available paired channels can be selected, and other settings can be configured by operating the buttons and dials on the operation unit 29. Furthermore, the LCD display unit 30 displays the mode setting status, the channel being used, the battery (not shown) consumption status, etc., and these functions are also managed and controlled by the system control unit 28.

<Communication frame format>
FIG. 4 is an example of a communication frame format used in group communication in the following embodiment.
On the transmitting side, a modulated wave modulated by MSK (Minimum Shift Keying) or the like using the baseband signal of the audio signal section incorporated in the same format is transmitted, and on the receiving side, the received signal related to the modulated wave is demodulated to reproduce the audio signal, while each information signal of the data payload received prior to the audio signal is separated and detected and used as data for operational control.
The data payload contains the device's own identification information, group identification information, and transmission/reception channel information, and can also be configured to set a channel change request signal if jamming radio waves are detected in the wireless repeater 50 or wireless communication terminals 60a, 60b, and 60c.
The communication frame format applied in the following embodiment has a cycle of 80 msec and is made up of 386 bits.

<Embodiment 1>
This embodiment 1 relates to the operation and system procedures of the repeater 50 and the communication terminals 60a, 60b, and 60c in a wireless communication system in which the wireless repeater (hereinafter abbreviated as "repeater") 50 and three wireless communication terminals (hereinafter abbreviated as "communication terminals") 60a, 60b, and 60c constitute a group communication network using a semi-duplex method when the repeater 50 receives jamming radio waves and changes the pair channel used for group communication to another available pair channel.

The wireless relay network diagram of Figure 5 shows that the transmission and reception channels for group communication in the group communication network are set to paired channel CH1, and that the relay 50 and each communication terminal 60a, 60b, and 60c are each in a standby state.
Here, in all wireless relay network diagrams from Figure 5 onwards (excluding Figures 20 to 22), the functional blocks RX01, RX02 and TX01 included in relay 50 indicate two receiving/demodulating units and modulating/transmitting units corresponding to those symbols in Figure 1, and the functional blocks RX11 and TX11 included in communication terminals 60a, 60b and 60c indicate a receiving/demodulating unit and modulating/transmitting unit corresponding to those symbols in Figure 2.
Furthermore, with regard to "CHi-X" (i=1, 2, X=L, H) which is appended to each of the above symbols relating to the receiving and demodulating unit and the modulating and transmitting unit with a colon (:), "CHi" corresponds to the channel number relating to the paired channel (see Figure 3), "L" or "H" indicates whether the channel is in the L wave band or the H wave band of the paired channel, and "SCAN-X" indicates the cyclic scanning state of all channels on the H band group side of Figure 3 for the receiving and demodulating unit RX02 of the repeater 50, and the cyclic scanning state of all channels on the L band group side of Figure 3 for the receiving and demodulating unit RX11 of the communication terminals 60a, 60b, and 60c.
In addition, in the functional blocks of the repeater 50 and the communication terminals 60a, 60b, and 60c, those not shaded indicate that they are in the ON state, and those shaded indicate that they are in the OFF state.

The wireless relay network diagram of FIG. 6 shows a relay communication state via the relay device 50 when the communication terminal 60a becomes the transmitting side and the communication terminals 60b and 60c become the receiving side from the standby state of FIG.
When communication terminal 60a transmits a call voice signal on channel CH1-H with receiver/demodulator RX11 in OFF state and modulator/transmitter TX11 in ON state, repeater 50 receives and demodulates the radio wave with receiver/demodulator RX01, switches modulator/transmitter TX01 from OFF state to ON state, and transmits a modulated signal, which is a carrier signal modulated with the demodulated call voice signal, on channel CH1-L. Meanwhile, when communication terminals 60b and 60c in standby mode capture the relayed radio wave during the cyclic scanning process of receiver/demodulator RX11, they immediately set receiver/demodulator RX11 to channel CH1-L and demodulate the received signal, thereby reproducing the sound from speaker 24.

Figure 6 shows the case where communication terminal 60a is the transmitting terminal, but regardless of which of communication terminals 60a, 60b, or 60c is the transmitting terminal, group communication is similarly carried out via repeater 50 using half-duplex mode with channel CH1-H as the upstream wave and channel CH1-L as the downstream wave.
However, since this is group communication, repeater 50 and communication terminals 60a, 60b, and 60c always include the code "01" as group identification information (hereinafter referred to as "G-ID") in the data payload of the transmitted signal, and demodulate the voice signal after confirming that G-ID: "01" is included in the data payload of the received demodulated signal.
Furthermore, in this embodiment, since the network communication is based on the specified low-power radio station/radio equipment for radio telephones/standard specifications of the above-mentioned non-patent document 1, the communication terminals 60a, 60b, 60c and the repeater 50 always perform carrier sense before transmitting radio waves, and transmit only after confirming that they are not receiving radio waves of a predetermined field strength or higher from other radio stations, etc.

The system control unit 16 of the repeater 50 controls the receiving channels of the receiving and demodulating unit RX02 to cyclically scan all 27 channels on the H band group side of Figure 3, thereby checking whether each channel is available or not, and always stores the confirmation information for one cyclic scan in the built-in memory using a ring buffer system.
Specifically, as shown by way of example in the right column of Figure 3, the flag of a channel that does not receive radio waves at a predetermined level or above is turned OFF and is therefore vacant, and conversely, the flag of a channel that receives radio waves at a predetermined level or above is turned ON. This operation is performed in a cycle for all 27 channels on the H band group side, thereby creating a scanning information table that is successively updated and stored in the built-in memory.

Furthermore, since the cyclic scanning in this case is not an implementation of carrier sensing, it is not subject to the restriction on carrier sensing on pages (1-10) of the above-mentioned Non-Patent Document 1, namely, "200 msec should be spent for each channel to determine whether the value of the received input power is equal to or greater than -96 dBm at the input point of the feeder," and although there is no difference in determining whether the value of the received input power is equal to or greater than a predetermined value, if there is no obligation to meet the time condition (200 msec), then in practice 25 msec per channel is sufficient.
Therefore, even if all 27 channels are scanned cyclically, the time required for one cyclic scan is about 675 msec (=25 msec×27).

In this embodiment, the receiver/demodulator RX02 scans the 27 channels mentioned above, but if the paired channels used in the wireless relay network are limited, then naturally only those limited channels (for example, 10 channels) will be scanned, and the scanning time for one cycle will be even shorter.

By the way, Figure 7 shows the case where repeater 50 is subjected to interference radio waves in the standby state (Figure 6), and shows the state where repeater 50 receives a call voice signal from a communication terminal 70 belonging to another group (G-ID: "02") via radio waves on channel CH1-H.
In this case, if the jamming radio wave signal is relayed by the repeater 50, communication will not be possible between the communication terminals 60a, 60b, and 60c of the group (G-ID: "01") that forms the communication network using the repeater 50.Therefore, the repeater 50 eliminates this inconvenience by executing the procedure shown in the flowchart of Figure 9.

First, when the receiver/demodulator RX01 of the repeater 50 receives radio waves of a predetermined field strength or greater in the standby state, the system control unit 16 checks the data payload of the received demodulated signal obtained from the receiver/demodulator RX01 and determines whether the group code “01” as the G-ID can be detected (S1 to S4).
In this case, the level of the electric field strength associated with radio wave reception by the receiver/demodulator RX01 can be determined taking into consideration whether it will interfere with voice communications, but as with the specified conditions for carrier sense, the standard can also be whether the received input power value is -96 dBm or higher at the power feed line input point.

In steps S1 to S4, if the electric field strength of the radio waves received by the receiver/demodulator RX01 is less than the criterion, it is not considered to be jamming radio waves and remains in standby mode (S1, S2: N → S1). Furthermore, if GID: "01" is detected in the data payload of the received demodulated signal, this indicates that radio waves transmitted from communication terminals 60a, 60b, and 60c within the group have been received, and since this is received by the receiver/demodulator RX01, this is nothing more than the reception of radio waves for normal telephone communication. As shown in Figure 6, normal relay operation is performed while the radio waves are being received, and the system returns to standby mode upon completion of communication (S4: Y → S5, S6 → S1).

On the other hand, if GID: "01" is not detected, it is possible that jamming radio waves are being received, so the built-in interval timer starts timing (S4:N→S7) and it is confirmed whether reception of the radio waves continues while maintaining the field strength (S8, S9).
If reception of the radio waves is interrupted before the specified time set in the interval timer has elapsed, the timer is reset and the device returns to standby mode (S7 → S8, S9 → S8:N → S10 → S1), but if the timer times out, the device resets the timer and then moves on to a procedure for changing the channel to be used in the wireless relay network (S9:Y → S11 to S18).

In this case, the jamming radio waves are assumed to be from a communication terminal 70 of another group as shown in Figure 7, but this does not exclude jamming radio waves from other radio wave sources.In order to target radio wave reception from communication terminals other than 60a, 60b, and 60c belonging to the group, the only condition for recognizing jamming radio waves is that GID: "01" is not detected (S4).
Furthermore, if the jamming radio waves do not continue for a predetermined time (for example, 1 second) or longer set in the interval timer, the channel used in the wireless relay network is maintained (S7 to S10 → S1), thereby avoiding frequent repeated changes of the channel used due to sudden jamming radio waves that do not significantly affect calls.

The first step in changing the channels used in the wireless relay network on the repeater 50 side is to turn off the receiver demodulator RX01 and switch the signal switching unit 13 to the CCR input side (S11) so that signals caused by jamming radio waves are not relayed and transmitted, and then change the currently set pair channels (CH1-H and CH1-L) of the receiver demodulator RX01 and the modulator/transmitter TX01 to an available pair channel selected based on the status information of each pair channel obtained by the receiver demodulator RX02 in the previous cyclic scan.
That is, the receiver-demodulator unit RX02 selects the vacant pair channel with the greatest frequency separation from the non-vacant pair channel among the vacant pair channels detected by a circular scan of the H band group in FIG. 3 immediately before the timeout, and changes the currently set pair channel (CH1-H and CH1-L) of the receiver-demodulator unit RX01 and the modulator-transmitter unit TX01 to the selected pair channel (S12, S13).

Specifically, let's say that the system control unit 16 creates a scanning information table in its internal memory that detects OFF vacant pair channels and ON non-vacant pair channels, as shown by the radio wave reception flags in the right column of Figure 3, based on the demodulated signal from the one round of scanning performed by the reception demodulation unit RX02 immediately before the timeout. If the channel number of the currently set pair channel for the reception demodulation unit RX01 and modulation transmission unit TX01 is 6 (= CH1), and there is jamming radio waves for that pair channel, then the vacant pair channel with the greatest frequency separation from the non-vacant pair channel in the scanning information table corresponds to channel number 32 (= CH2), and so that vacant pair channel (CH2-H and CH2-L) will be changed and set for the reception demodulation unit RX01 and modulation transmission unit TX01.

The method for finding the "vacant pair channel with the largest frequency separation from a non-vacant pair channel" is as follows.
(1) In the column of the radio wave reception flag, if there is an ON on both sides of an OFF or on both ends of a continuous OFF section, the interval between the channel frequencies related to the ON on both sides or both ends is found.
(2) In the column of radio wave reception flags, when the flag for channel number 1 is OFF, the interval between the channel frequency of the smallest channel number whose flag is ON and the channel frequency of channel number 1 is found.
(3) In the radio wave reception flag column, if the flag for channel number 40 is OFF, the interval between the channel frequency for channel number 40 and the channel frequency for the largest channel number whose flag is ON is found.
(4) Compare half the interval found in (1), the interval found in (2), and the interval found in (3). If the value of (1) is the largest, select the paired channel related to the OFF channel sandwiched between ONs or the paired channel related to the channel with the frequency closest to the arithmetic average of the ON channel frequencies at both ends. If the value of (2) is the largest, select the paired channel with channel number 1. If the value of (3) is the largest, select the paired channel with channel number 40.
Based on the radio wave reception flags in the right column of FIG. 3, the corresponding pair channel determined by the algorithm (4) is channel number 32 (=CH2) as described above.

Figure 8 shows the state in which the receiver/demodulator RX01 and modulator/transmitter TX01 of repeater 50 have been changed and set to an available pair of channels (CH2-H and CH2-L). Repeater 50 has switched to the pair of channels with channel number CH2, and is no longer affected by jamming signals from communication terminal 70. However, communication terminals 60a, 60b, and 60c are still set to the channel used by the previous wireless relay network (CH1). Therefore, repeater 50 must send GID: "01" and a channel change request signal (hereinafter referred to as "CCR") to communication terminals 60a, 60b, and 60c to set the pair of channels with channel number CH2.

Therefore, the repeater 50 will turn on the modulation transmission unit TX01, which has been changed to CH2-L, and transmit the CCR, but prior to transmission, it is necessary to perform carrier sensing for the paired channels (CH2-H, CH2-L) using the reception demodulation unit RX01 (S14).
In this case, since the previous scan confirmed that the paired channel of channel number CH2 was free, the carrier sense result should be almost always idle, indicating that transmission is possible. However, if interference related to the paired channel of channel CH2 happens to occur after the previous scan, the result may be busy, indicating that transmission is not possible.

Therefore, when the carrier sense result indicates a busy state, the free pair channel with the second largest frequency separation from the non-free pair channel in the scanning information table (corresponding to channel number 9 in the scanning information table) is selected and carrier sense is re-executed (S12 to S15:N → S16 → S13).
In addition, for the paired channel of the channel number that has become busy, the radio wave reception flag is subsequently changed to ON and the separation degree is compared and determined, and thereafter, the free paired channel with the mth largest separation degree is selected in the same manner, but generally it is extremely rare for the third or subsequent paired channels to be selected.

If the result of the carrier sense is an idle state, the repeater 50 turns on the modulation transmission unit TX01 as shown in FIG. 8, incorporates GID: “01” and CCR into the data payload of the communication frame, and transmits the communication frame repeatedly for a certain period of time (for example, 1 second) on the channel (CH2-L) of the modified modulation transmission unit TX01, with the audio signal portion used as dummy data for adjusting the frame length (S15 → S17).
When the transmission of the signal is completed, the modulation transmission unit TX01 is turned off and the signal switching circuit unit 13 is switched to the input side of the demodulated signal of the reception demodulation unit RX01, returning to the standby state (S18→S1).
Note that Figure 8 shows a state in which the first carrier sense on the paired channel (CH2-L) with the greatest frequency separation from the non-vacant paired channel is in the idle state, and the modulation transmitter TX01 transmits GID: "01" and CCR on that channel (CH2-L).

Meanwhile, at this stage, each communication terminal 60a, 60b, 60c is in standby mode, the modulation transmission unit TX11 is in the OFF state and remains on the previously set channel (CH1-L), but the reception demodulation unit RX11 is cyclically scanning all channels on the L band group side of Figure 3, and the GID: "01" and CCR transmitted from repeater 50 are received during the cyclic scanning process of the reception demodulation unit RX11 of each communication terminal 60a, 60b, 60c and detected from the demodulated signal.

FIG. 10 shows the procedure for changing the transmission/reception setting channel on the side of each of the communication terminals 60a, 60b, and 60c.
First, in each of the communication terminals 60a, 60b, 60c, when the reception demodulation unit RX11 receives a radio wave having a predetermined field strength or more during the cyclic scanning in the standby state, the cyclic scanning is temporarily stopped for that receiving channel (S21 to S23).

Here, with regard to the cyclic scanning of the receiving and demodulating unit RX11 of each communication terminal 60a, 60b, 60c, similar to the receiving and demodulating unit RX02 of the repeater 50, all 27 channels on the L band group side of Figure 3 are scanned at 675 msec per cycle, and it is determined for each individual channel in approximately 25 msec whether radio waves above a predetermined level are received.
In this case, as described above, the communication frame from the repeater 50 side is transmitted in 80 msec in one cycle (386 bits), and approximately 8.44 frames (= 675/80) are continuously received during one round of scanning in the receiving and demodulating unit RX11 of each communication terminal 60a, 60b, 60c.
Therefore, in each communication terminal 60a, 60b, 60c, if radio waves above a predetermined level are received during the cyclic scanning process of the receiving and demodulating unit RX11, this can be confirmed, the cyclic scanning can be stopped on that receiving channel, and GID: "01" and CCR can be detected from the data payload of the demodulated communication frame (S23 to S26).

If GID: "01" is detected in the data payload of the communication frame, it must be a communication frame received from a repeater 50 in the group (S25: Y), and if a CCR is further detected, it means that a request to change the network channel has been made by the repeater 50 that has received jamming radio waves as described above (S26: Y).
Therefore, in each of the communication terminals 60a, 60b, and 60c, the modulation transmission unit TX11 is changed to a channel that is paired with the scanning stopped channel of the reception demodulation unit RX11 where the CCR was detected (S27).
Also, although the receiving and demodulating unit RX11 is in the channel where scanning has been stopped, it resumes the cyclic scanning and returns to the standby state (S28 → S21).

As a result, if the modulation transmitter TX01 of the repeater 50 transmits GID: "01" and CCR on channel (CH2-L) and the scan stop channel of the receiver/demodulator RX11 of each communication terminal 60a, 60b, and 60c is (CH2-L), as shown in Figure 11, the receiver/demodulator RX01 and modulation transmitter TX01 of the repeater 50 are set to a pair of channels (CH2-H, CH2-L), the receiver/demodulator RX02 enters a cyclic scanning state, and the modulation transmitter TX11 of each communication terminal 60a, 60b, and 60c is set to channel (CH2-H), the receiver/demodulator RX11 enters a cyclic scanning state, and the group communication network enters a standby state.

Therefore, as shown in Figure 12, when one of communication terminals 60a, 60b, or 60c (communication terminal 60a in the figure) transmits a call voice signal including GID: "01" from its modulation transmission unit TX11 on the upstream channel (CH2-H), repeater 50 receives and relays it and transmits it on the downstream channel (CH2-L). Meanwhile, in the communication terminals (60b, 60c) other than the transmitting communication terminal (60a), their respective reception and demodulation units RX11 receive the radio waves during the scanning phase of channel (CH2-L) in the cyclic scanning, and with cyclic scanning stopped on that channel, receive, demodulate, and play back the voice signal of the subsequent communication frame.

As a result, when the network channel for group communication using semi-duplex between communication terminals 60a, 60b, and 60c via repeater 50 is the paired channel with channel number CH1 in standby mode (Figure 5), if there is jamming radio waves at repeater 50 (Figure 7), the network channel is automatically changed to the paired channel with channel number CH2 (Figure 11), and the system transitions to a state where group communication is possible without being affected by jamming radio waves (Figure 12).

In step S22 of FIG. 10, if the receiver/demodulator RX11 does not receive radio waves with a field strength above the predetermined level (S22:N) and the PTT button on the operation unit 29 is turned ON to set the transmission mode, the receiver/demodulator RX11 is turned OFF and the modulator/transmitter TX11 is turned ON, carrier sensing is performed, and the call signal is transmitted. When the PTT button is turned OFF and the communication ends, the receiver/demodulator RX11 is returned to the cyclic scanning state and the modulator/transmitter TX11 is turned OFF, returning to the standby state (S22:N → S30:Y → S31-S34 → S21).

Furthermore, if GID: "01" is detected but CCR is not detected in steps S25 and S26 of Figure 10, which means that normal reception is occurring via repeater 50 in the group communication network, the mute setting of amplifier 23 is canceled, and the call signal received on the reception channel of reception demodulation unit RX11 (the channel for which cyclic scanning was stopped in step S23) is demodulated and audio is played back. When the communication ends, the amplifier 23 is muted, and cyclic scanning of reception demodulation unit RX11 is resumed, and the system returns to standby mode (S25:Y → S26:N → S35-S38 → S21).

In addition, if GID: "01" is not detected in step S25, this corresponds to the case where communication terminals 60a, 60b, and 60c are receiving jamming radio waves, and the operation procedure will proceed to that shown in Figure 15 in embodiment 2 below (S25:N → A → Figure 15 → B → S21).

<Embodiment 2>
As in the case of embodiment 1, this embodiment 2 relates to a wireless communication system in which the repeater 50 and communication terminals 60a, 60b, and 60c form a group communication network using a semi-duplex method, but relates to the operation of the repeater 50 and communication terminals 60a, 60b, and 60c and the system procedures when one of the communication terminals 60a, 60b, and 60c receives jamming radio waves and changes the pair channel used for group communication to another available pair channel.

Figure 13 shows a case where there is interference with communication terminal 60a in the standby state of Figure 5, and shows a state in which communication terminal 60a receives a call voice signal from communication terminal 80 belonging to another group (GID: "02") via radio waves on channel (CH1-L).
Here, the communication terminal 80, which is the source of the jamming radio waves, has the opposite transmission and reception channel to that of the communication terminal 70 in the above-mentioned embodiment 1, but in a wireless relay system in which control information is transmitted and received intermittently between multiple repeaters, adjacent repeaters often have the transmission and reception channels set opposite to each other, and when a communication terminal belonging to the network of one adjacent repeater enters the area of the network of the other repeater, the relationship becomes similar to that of communication terminal 80 in this embodiment 2.
In this case, since there is an interfering radio wave on the channel (CH1-L) that is paired with the transmission channel (CH1-H) of communication terminal 60a, even if carrier sensing is performed, the channel becomes busy and communication terminal 60a is unable to transmit.

In the state of Figure 13, the jamming radio wave signal is received and demodulated during the cyclic scanning process of the receiving and demodulating unit RX11 in the communication terminal 60a, and the control operation by the system control unit 28 of the communication terminal 60a in this case is shown in steps S21 to S25 of Figure 10 (common to the case of embodiment 1) and Figure 15.
First, as explained in the first embodiment, the receiver/demodulator RX11 of each communication terminal 60a, 60b, 60c scans all 27 channels on the L band group side of Figure 3 at 675 msec per cycle, and determines whether or not radio waves above a predetermined level are being received for each individual channel in approximately 25 msec. When the receiver/demodulator RX11 of the communication terminal 60a is in standby mode and receives radio waves above a predetermined field strength during the cyclic scanning process, it temporarily stops cyclic scanning on that receiving channel (Figure 10: S21 to S23).

If GID: "01" is detected in the data payload of a communication frame demodulated by the receiver/demodulator RX11, which has stopped cyclic scanning in communication terminal 60a, then the communication frame is received from a repeater 50 in the group (FIG. 10: S24, S25: Y → S26). As explained in embodiment 1, depending on whether or not a CCR is detected, the communication channel of the terminal will either be changed (FIG. 10: S26: Y → S27, S28) or the terminal will transition to normal call signal reception/playback mode (FIG. 10: S26: N → S35-S38). However, if GID: "01" is not detected in the data payload of the communication frame, it may be experiencing jamming signals, in which case the terminal will be treated as in embodiment 2 (FIG. 10: S25: N → A → FIG. 15: S41-S50).

In the communication terminal 60a, if GID: "01" is not detected in the data payload of the communication frame demodulated by the receiving and demodulating unit RX11, the system control unit 28 starts timing using the built-in interval timer (Figure 15: S41) and checks whether reception of the radio wave continues for a predetermined time while maintaining the field strength (S42, S43).
If reception of the radio waves is interrupted before the specified time set in the interval timer has elapsed, the timer is reset and the device returns to standby mode (S42: N → B → Figure 10: S21), but if the timer times out, the device resets the timer and then moves on to a procedure for changing the channel used in the wireless relay network (S43: Y → S44 to S50).

That is, the receiver/demodulator RX11 selects the free pair channel with the greatest frequency separation from the non-free pair channel among the free pair channels detected by a circular scan of the L band group in Figure 3 immediately before the timeout, and changes the currently set channel (CH1-H) of the modulator/transmitter TX11 to the channel associated with the selected free pair channel (S44, S45).

This is the same operating procedure as in the case of the repeater 50 (FIG. 9: S12, S13). If the system control unit 28 creates a scanning information table in its internal memory in which OFF vacant pair channels and ON non-vacant pair channels are detected, as shown by the radio wave reception flags in the right column of FIG. 3, based on the demodulated signal from the one cyclic scan performed by the receiving and demodulating unit RX11 immediately before the timeout, and the channel number of the currently set pair channel of the receiving and demodulating unit RX11 and the modulating and transmitting unit TX11 is 6 (=CH1), when there is jamming radio waves for that pair channel, the vacant pair channel with the greatest frequency separation from the non-vacant pair channel in the scanning information table corresponds to channel number 32 (=CH2), and therefore that vacant pair channel (CH2-L and CH2-H) is changed and set to the receiving and demodulating unit RX11 and the modulating and transmitting unit TX11.
The method for determining the "vacant pair channel having the largest frequency separation from the non-vacant pair channel" is the same as the algorithm explained for the repeater 50 in the first embodiment, and will not be described here.

Figure 14 shows the state in which the receiver/demodulator RX11 and modulator/transmitter TX11 of communication terminal 60a have been reconfigured to an available pair of channels (CH2-L and CH2-H). Communication terminal 60a has switched to the pair of channels with channel number CH2, and is no longer affected by jamming signals from communication terminal 80. However, repeater 50 and communication terminals 60b and 60c are still configured with the previous pair of channels (channel number CH1) of the wireless relay network, and will change their configured pair of channels to the available pair of channels (channel number CH2).

Therefore, as shown in the figure, in the communication terminal 60a, the receiver/demodulator RX11 performs carrier sensing on channel CH2-L, and if it is confirmed that the channel is in the idle state, the modulator/transmitter TX11 is immediately turned on and transmits GID: "01" and CCR repeatedly for one second, and then the cyclic scanning of the receiver/demodulator RX11, which had been stopped, is resumed and the communication terminal 60a returns to the standby state (FIG. 15: S46, S47: Y → S49, S50 → B → FIG. 10: S21).
However, if the paired channel (channel number: CH2) becomes used by another group, etc., between the time when the receiver/demodulator unit RX11 performs a full scan immediately before the timeout and the time when carrier sense is performed, and the result of carrier sense becomes busy, the paired channel with the next largest frequency separation from the non-vacant paired channel is set and carrier sense is performed, and thereafter, even if the result of carrier sense becomes busy, carrier sense is similarly performed by selecting paired channels in descending order of frequency separation (S47:N → S48 → S45 to S47).
However, as in the case of the repeater 50 in embodiment 1, the idle state is usually achieved with the first pair channel setting condition, and it is rare for the second, third, or subsequent selections to be made.

As shown in Figure 14, the GID: "01" and CCR signals transmitted from the modulation transmitter TX11 of the communication terminal 60 on the changed channel (CH2-H) are only received during the cyclic scanning process of the receiver/demodulator RX02 of the repeater 50 in standby mode, and cannot be received by the receiver/demodulator RX11 on the communication terminals 60b and 60c side, as they are controlled to cyclically scan the L band group side in Figure 3.

FIG. 16 shows the reception/transmission operation relating to the relay of the CCR in the repeater 50 in this case.
First, in the repeater 50, the receiver/demodulator RX02 constantly cyclically scans the H band group shown in Figure 3. If a radio wave with a predetermined field strength or higher is received during this process, the system controller 16 temporarily stops the cyclic scanning on that receiving channel and checks whether GID: "01" and CCR are detected in the data payload of the demodulated communication frame (S61 to S64).

If GID: "01" and CCR are detected, the system control unit 16 executes the following operation procedures (1) to (4) as interrupt processing (S64: Y → S65 to S71).
(1) The receiver/demodulator RX01 and the modulator/transmitter TX01 are set as a pair of channels, with the channel of the receiver/demodulator RX02 in which the CCR was detected being the H-band group channel (S66).
(2) The signal switching unit 13 is switched to the CCR side (S67).
(3) The receiver/demodulator RX01 performs carrier sensing (S68).
(4) If the result of carrier sense is an idle state, the modulation transmitter TX01 transmits GID: "01" and CCR repeatedly for one second on the channel (S69: Y → S70).
Also, when the interrupt processing is completed, or when GID: "01" and CCR are not detected in step S64, the cyclic operation of the receiving and demodulating unit RX02 is resumed and the process returns to the original state (S71/S64 → S72 → S61).

Therefore, in repeater 50, when the receiver/demodulator RX02 receives GID: "01" and CCR on channel CH2-H from communication terminal 60a that has received jamming radio waves, it changes the pair of channels used for relaying, i.e., the set channel of receiver/demodulator RX01 and modulator/transmitter TX01, from (CH1-H, CH1-L) to (CH2-H, CH2-L), as shown in Figure 17, and transmits GID: "01" and CCR to communication terminals 60a, 60b, and 60c on the transmission channel (CH2-L).

On the other hand, when communication terminal 60a receives jamming radio waves, the communication channel pair is changed to (CH2-L, CH2-H), but the communication channel pair of communication terminals 60b and 60c remains (CH1-L, CH1-H).
However, in the standby state, the reception/demodulation units RX11 of the communication terminals 60a, 60b, and 60c are in a state of cyclically scanning the channels on the L band group side in FIG.

Therefore, when looking at the relationship between the repeater 50 and communication terminals 60a, 60b, and 60c in the wireless relay network state, in Figure 8 of the first embodiment, the transmission and reception channel of communication terminal 60a has not been changed, so the channel of its modulation transmitter TX11 is CH1-H. However, apart from this, Figure 8 of the first embodiment and Figure 17 of this second embodiment are the same, and steps S21 to S28 of Figure 10 of the first embodiment are applied as is to the operating procedures of communication terminals 60b and 60c.

That is, the set channels of the receiver/demodulator RX11 and the modulator/transmitter TX11 of the communication terminals 60b and 60c are changed to a pair of channels (CH2-L, CH2-H) in which the scanning stop channel of the receiver/demodulator RX11 where the CCR was detected is set as the channel on the L band group side, and the receiver/demodulator RX11 then switches to cyclic scanning operation (S27, S28).
In addition, a similar change setting procedure may be performed for communication terminal 60a, but since the transmission and reception channels have already been changed and set to paired channels (CH2-L, CH2-H), even if GID: "01" and CCR are received from repeater 50, they may be ignored.

Note that if the carrier sense result in the interrupt process of FIG. 16 indicates a busy state (steps S68, S69: N), the repeater 50 may execute the operational procedure of steps S12 to S18 → S1 in FIG. 9 to set an available pair channel using its own scanning information table (the radio wave reception flag in the right column of FIG. 3).

As a result, as shown in FIG. 18, the pair channel used in the relay communication network formed by the relay device 50 and each communication terminal 60a, 60b, 60c is changed to channel number CH2 and enters a standby state.
As shown in Figure 19, even if there is interference radio waves to communication terminal 60a, voice call communication can be carried out between communication terminals 60a, 60b, and 60c via repeater 50 using the pair channel with channel number CH2 without any effect, just as in the case of Figure 12 in the above-mentioned embodiment 1.

This invention can be applied to radio relay network systems using a half-duplex method that uses paired channels that can be used in radio equipment for specified low-power radio stations/radio telephones, radio equipment for land mobile radio stations (for work communication) with an antenna power of 1 mW or less, and radio equipment for digital simplex radio stations.

11...receiving antenna, 12...amplifier, RX01, RX02...receiving and demodulating unit, 13...signal switching unit, TX01...modulating and transmitting unit, 14...amplifier, 15...transmitting antenna, 16...system control unit, 17...operating unit, 18...various indicator lamps, 20...transmitting and receiving antenna, 21...antenna switching unit, 22...amplifier, RX11...receiving and demodulating unit, 23...amplifier, 24...speaker (or earphone), 25...microphone, 26...amplifier, TX11...modulating and transmitting unit, 27...amplifier, 28...system control unit, 29...operating unit, 30...display unit, 50...wireless repeater, 60a, 60b, 60c...wireless communication terminal, 70, 80...wireless communication terminal (source of jamming radio waves), 100...wireless repeater, 201, 202...wireless communication terminal, 301...wireless communication terminal (source of jamming radio waves).

Claims (6)

A wireless relay system comprising a wireless repeater and a plurality of wireless communication terminals constituting one group, wherein one paired channel is selected from a group of two channels (hereinafter referred to as "paired channels") that are paired waves that can be used for uplink and downlink waves for communication between the wireless repeater and each wireless communication terminal in the standard established based on the Radio Law Enforcement Regulations and the Radio Equipment Regulations, and performs group communication between the wireless communication terminals by a semi-duplex method,
The wireless repeater is
The system comprises a receiving and demodulating unit A, a receiving and demodulating unit B, a modulating and transmitting unit C, and a control unit for controlling them, and the one pair channel is set to the receiving and demodulating unit A and the modulating and transmitting unit C, while the receiving and demodulating unit B cyclically scans a group of channels that can be used as receiving channels for the receiving and demodulating unit A and searches for an available channel, and in a standby and receiving mode, the receiving and demodulating units A and B are in an ON state, and the modulating and transmitting unit C is in an OFF state, and when group identification information relating to the group is detected and confirmed from the demodulated signal of the receiving and demodulating unit A, the system switches to a repeating mode, and in the repeating mode the modulation-transmission unit C is turned on, and the carrier wave of the transmission channel is modulated with the demodulated signal output by the reception-demodulation unit A and transmitted; and in addition, in the standby/reception mode, when the reception-demodulation unit A receives radio waves of a certain field strength or more from which the group identification information cannot be detected and confirmed in the demodulated signal for a predetermined period of time or more, the set pair channel of the reception-demodulation unit A and the modulation-transmission unit C is changed to the pair channel related to the vacant channel searched for by the reception-demodulation unit B, and the modulation-transmission unit C is turned on to transmit the group identification information and channel change request information;
Each of the wireless communication terminals
The radio communication system includes a receiving and demodulating unit D, a modulating and transmitting unit E, and a control unit for controlling them, and the pair channels set in the receiving and demodulating unit A and the modulating and transmitting unit E on the wireless repeater side are set in the receiving and demodulating unit D and the modulating and transmitting unit E in an inverse relationship for transmission and reception, while in a standby mode, the receiving and demodulating unit D cyclically scans a group of channels that can be used as receiving channels, and in a reception mode, the receiving and demodulating unit D is in an ON state and the modulating and transmitting unit E is in an OFF state, and a demodulated signal output by the receiving and demodulating unit D is reproduced as audio, and in a transmission mode, the receiving and demodulating unit D is in an OFF state and the modulating and transmitting unit E is in an ON state, and a carrier wave of a transmission channel of the modulating and transmitting unit E is modulated with an input audio signal and transmitted, and in addition, in the standby mode, when the receiving and demodulating unit D receives the group identification information and the channel change request information transmitted from the wireless repeater side during the cyclic scanning process, the receiving channel and the channel that is in a pair channel relationship with the receiving channel are set in the receiving and demodulating unit D and the modulating and transmitting unit E, respectively. A radio relay system characterized by: The wireless repeater system of claim 1, wherein when the receiver/demodulator A receives radio waves above a certain field strength for a predetermined period of time or longer, from which the group identification information cannot be identified from the demodulated signal, and multiple vacant pair channels are detected during a circular scanning process by the receiver/demodulator B immediately before the reception for that predetermined period of time or longer is detected, the receiver/demodulator A and the modulator/transmitter C are reconfigured to select the vacant pair channel whose frequency is the greatest relative to a non-vacant pair channel, and the modulator/transmitter C transmits the group identification information and channel change request information. The wireless repeater system described in claim 2, wherein when carrier sensing is performed using the receiver-demodulator A prior to the transmission operation of the modulator-transmitter C, the wireless repeater selects available pair channels in descending order of frequency separation from non-available pair channels and performs carrier sensing. A wireless relay system comprising a wireless repeater and a plurality of wireless communication terminals constituting one group, wherein one paired channel is selected from a group of two channels (hereinafter referred to as "paired channels") that are paired waves that can be used for uplink and downlink waves for communication between the wireless repeater and each wireless communication terminal in the standard established based on the Radio Law Enforcement Regulations and the Radio Equipment Regulations, and performs group communication between the wireless communication terminals by a semi-duplex method,
The wireless repeater is
The system comprises a receiving and demodulating unit A, a receiving and demodulating unit B, a modulating and transmitting unit C, and a control unit for controlling them, and the one pair channel is set to the receiving and demodulating unit A and the modulating and transmitting unit C, while the receiving and demodulating unit B cyclically scans a group of channels that can be used as a receiving channel for the receiving and demodulating unit A, and in a standby and receiving mode, the receiving and demodulating units A and B are in an ON state, and the modulating and transmitting unit C is in an OFF state, and when group identification information relating to the group is detected and confirmed from the demodulated signal of the receiving and demodulating unit A, the system switches to a repeating mode, and in the repeating mode, the modulating and transmitting unit C and when the receiving and demodulating unit B receives the group identification information and the channel change request information transmitted by any of the wireless communication terminals during the cyclic scanning in the standby and receiving mode, the receiving and demodulating unit B sets the receiving channel and the channel which is paired with the receiving channel in the receiving and demodulating unit A and the modulating and transmitting unit C, respectively, and transmits the group identification information and the channel change request information from the modulating and transmitting unit C.
Each of the wireless communication terminals
The radio repeater is provided with a receiving and demodulating unit D, a modulating and transmitting unit E, and a control unit for controlling them, and the pair channels set in the receiving and demodulating unit A and the modulating and transmitting unit E on the wireless repeater side are set in an inverse relationship for transmission and reception, while in a standby mode, the receiving and demodulating unit D cyclically scans a group of channels that can be used as receiving channels and searches for an available channel, and in a receiving mode, the receiving and demodulating unit D is in an ON state and the modulating and transmitting unit E is in an OFF state, and the demodulated signal output by the receiving and demodulating unit D is reproduced as audio, and in a transmitting mode, the receiving and demodulating unit D is in an OFF state and the modulating and transmitting unit E is in an ON state, and the carrier wave of the transmission channel of the modulating and transmitting unit E is modulated with an input audio signal and transmitted, and In a standby mode, when the receiving and demodulating unit D receives radio waves of a certain field strength or more for a predetermined period of time or more, and the group identification information cannot be detected or confirmed from the demodulated signal, the set pair channel of the receiving and demodulating unit D and the modulating and transmitting unit E is changed to the pair channel related to the available channel searched by the receiving and demodulating unit D, and the modulating and transmitting unit E is turned on to transmit the group identification information and the channel change request information, while when the receiving and demodulating unit D receives the group identification information and the channel change request information sent by the wireless repeater side during its cyclic scanning process, the receiving channel and the channel that is in a pair channel relationship with it are set in the receiving and demodulating unit D and the modulating and transmitting unit E, respectively. The wireless relay system of claim 4, wherein in the wireless communication terminal, when the receiver/demodulator unit D receives radio waves above a certain field strength for a predetermined period of time or longer, from which the group identification information cannot be identified from the demodulated signal, and when multiple vacant pair channels are detected during a circular scanning process by the receiver/demodulator unit D immediately before the detection of reception for that predetermined period of time or longer, the receiver/demodulator unit D and the modulator/transmitter unit E are reconfigured to select the vacant pair channel whose frequency is the greatest difference from a non-vacant pair channel, and the modulator/transmitter unit E transmits the group identification information and channel change request information. The wireless relay system described in claim 5, wherein when the wireless communication terminal performs carrier sensing using the receiver-demodulator unit D prior to the transmission operation of the modulator-transmitter unit E, the wireless communication terminal selects available pair channels in descending order of frequency separation from non-available pair channels and performs carrier sensing.