Wireless relay system

Abstract

In a wireless relay system that uses a half-duplex group communication method with paired waves, communication becomes impossible if there is interference from radio waves on the relay or communication terminal. [Solution] The repeater 50 includes a modulation transmitter TX01 and a receiver demodulator RX01 for communication, along with a receiver demodulator RX02 that always scans a group of available channels to search for an available pair wave. Each communication terminal 60 includes a modulation transmitter TX11 and a receiver demodulator RX11 that has the aforementioned scanning function in standby mode. If there is interference from radio waves on the repeater 50's RX01, the repeater 50 changes the pair wave to the one with the greatest distance from the non-available pair wave among the available pair waves searched by RX02 and sends a channel change request (CCR) from TX01. Each communication terminal 60 receives the CCR during the scanning process of RX11 and changes TX11 and RX11 to the transmit / receive pair wave corresponding to the receiving channel of the CCR.

Description

Technical Field

[0001] The present invention relates to a wireless relay system comprising a wireless repeater and a plurality of wireless communication terminals that communicate with each other in a half-duplex manner through the wireless repeater. When there is interference radio wave to the wireless repeater or the wireless communication terminal, the currently used pair channel is automatically changed to an available pair channel.

Background Art

[0002] Conventionally, in group communication using a business wireless communication device which is a specific low-power radio station, a wireless repeater (parent station) is often provided for the purpose of expanding the communication area to enable communication between multi-story buildings or separate buildings, ensuring calls in areas where radio waves are difficult to reach due to obstacles, etc., and improving call quality. A group communication network is constituted by wireless communication terminals via the wireless repeater. Also, in a business wireless communication device which is a radio station (for work communication) of a land mobile service with an antenna power of 1 mW or less, communication between child stations via the parent station is basically used, and it becomes the same group communication network as described above.

[0003] And in those networks, communication between each wireless communication terminal via the wireless repeater is in a half-duplex manner. For the uplink and downlink related to the communication, a pair channel (opposite wave) is used. The available pair channels are determined according to the radio wave type and communication method based on the standards established in the Radio Law Enforcement Regulations and the Radio Equipment Regulations (see Non-Patent Documents 1 and 2 below). When the wireless repeater and each wireless communication terminal correspond to specific low-power radio stations, 27 sets of pair channels shown in FIG. 3 can be used.

[0004] Here, assume 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. 20. The wireless repeater 100 and each wireless communication terminal 201, 202 are in a state where they are using a pair channel with channel number CH1, and the L-band and H-band channels of this pair channel are set in the wireless repeater 100 and each wireless communication terminal 201, 202 in an inverse relationship for transmission and reception. Specifically, the receiver demodulator RX01 of the wireless repeater 100 is set to the H-band channel of channel number CH1, and the modulation transmitter TX01 is set to the L-band channel of the same channel number. The receiver demodulators RX11 and RX21 of each wireless communication terminal 201, 202 are set to the L-band channel of channel number CH1, and the modulation transmitters TX11 and TX21 are set to the H-band channel of the same channel number. Furthermore, the group identification information for this group communication network is set to the code "01". This code is always included in the signal when communicating, and the detection and verification of this code is performed when receiving data.

[0005] Therefore, when wireless communication terminal 201 initiates a call to wireless communication terminal 202 from the standby state shown in Figure 20, as shown in Figure 21, the uplink from wireless communication terminal 201 to wireless repeater 100 will be on the H-band channel of channel number CH1, and the downlink will be on the L-band channel of the same channel number. Conversely, the same channel usage conditions apply when wireless communication terminal 202 initiates a call to wireless communication terminal 201, allowing each wireless communication terminal 201 and 202 to intermittently perform half-duplex communication with transmission and reception alternating.

[0006] By the way, if another communication network is started in an area close to the operating area of ​​the aforementioned group communication network, and as shown in Figure 22, when a wireless communication terminal 301 (group identification information code "02") from outside the group uses channel number CH1 for communication during the standby state between communications, the wireless repeater 100 will be occupied, and communication between each wireless communication terminal 201, 202 (group identification information code "01") within the network will become impossible. Furthermore, the cause of this communication failure is not limited to radio waves from wireless communication terminal 301 outside the group, as described above; communication failure can also occur in the presence of a strong noise source nearby.

[0007] In that case, group communication can be resumed by waiting until the interference on channel number CH1 ends, but it is uncertain when the interference will occur again, and stable communication cannot be expected as long as the paired channel of channel number CH1 is used. Therefore, the optimal solution is to change the current pair channel used in the group communication network to another available pair channel.

[0008] To address this problem, Patent Document 1 below proposes a repeater device and a communication terminal that maintain wireless relay functionality even when communication becomes impossible due to interference, fading, etc. This repeater device includes a control channel repeater and multiple communication channel repeaters, each of which functions as a repeater at its respective set transmission and reception frequencies. However, the so-called control channel here is assumed to correspond to a frequency control channel specially provided as channel number 19, in addition to the 27 pairs of channels shown in Figure 3, in the case of the aforementioned low-power radio station. On the other hand, each communication terminal communicating via the 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 transmitted to the repeater device via the control channel before transmitting it.

[0009] The repeater device includes, as functional means, a control channel state 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 a preset threshold information, a communication channel idle line detection means for detecting whether a communication channel repeater is in an idle line state, a control channel switching information generation means for generating information to switch an idle 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 a control channel repeater based on the control channel switching information. This allows a communication channel repeater with a good communication state to take over the function of a control channel repeater when the communication state of the control channel repeater deteriorates.

[0010] Therefore, the proposal in Patent Document 1 below involves having a communication channel repeater that is in an empty state take over the function of the control channel repeater when interference radio waves occur on the control channel and the control channel repeater becomes inoperable. However, paragraph

[0007] states that "with regard to communication channel repeaters, if the communication quality deteriorates, it is possible to maintain normal relay function by using a normal control channel repeater or control channel as a communication channel," suggesting that even if interference radio waves occur on the communication channel, it is possible to switch from the communication channel repeater to another communication channel repeater. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2009-267685 [Non-patent literature]

[0012] [Non-Patent Document 1] The Association of Radio Industries and Businesses, "Standards for Low-Power Radio Stations / Radio Telephone Equipment," RCR STD-20 5.1, revised October 29, 2021. [Non-Patent Document 2] The Association of Radio Industries and Businesses, "Radio Equipment / Standards for Radio Stations for Land Mobile Services (requiring operational communication) with Antenna Power of 1mW or Less," RCR STD-31 4.0, revised September 28, 2020. [Overview of the project] [Problems that the invention aims to solve]

[0013] As described above, the proposal in Patent Document 1 describes a repeater device in which, when interference occurs on the control channel, the function of the control channel repeater is transferred to the communication channel repeater. Furthermore, although not specifically disclosed, if interference occurs on the communication channel, the function is transferred from the communication channel repeater to another communication channel repeater or control channel repeater.

[0014] However, the repeater device is equipped with a channel repeater as a unit for each channel (a control channel repeater and multiple communication channel repeaters), and each channel repeater is equipped with a receive demodulation unit and a modulated transmit unit, each with its own transmit and receive frequency (paired channels in the case of a low-power radio station). Therefore, if a repeater device were to be able to handle n pairs of channels, it would naturally be an expensive device, as it would incorporate n+1 receiving / demodulating units and n+1 modulation / transmitting units, including the control channel. In the case of a half-duplex wireless relay system, a large number of unused communication channel repeaters would be generated, resulting in extremely poor utilization efficiency.

[0015] Furthermore, in the case of the repeater device, if interference occurs on a communication channel during relay operation, it is acceptable to switch from the communication channel repeater to another communication channel repeater, but when notifying the communication terminal of the information regarding the change of communication channel, a control channel repeater will be used. In that case, since the control channel is a channel used to send and receive information for the purpose of frequency control, it tends to be used more frequently than other communication channels. Therefore, if a similar communication network is operating in a nearby area, there is a high possibility that it will remain busy and unavailable.

[0016] Furthermore, if interference occurs in one communication channel repeater and the relay operation is switched to a communication channel repeater that is in an empty state, if there are many communication channel repeaters, the communication channel empty channel detection means may detect many communication channel repeaters that are in an empty state. However, even if a communication channel is considered to be in an empty state, radio interference may occur if a communication channel of an adjacent frequency is in use.

[0017] This invention was created in consideration of the above problems, and aims to rationally implement, with a relatively simple configuration and without using a control channel, a function that automatically changes the currently used pair channel to another available pair channel when the wireless repeater or wireless communication terminal detects and confirms interference radio waves on the currently used pair channel. This function is used in a wireless communication system consisting of a wireless repeater and multiple wireless communication terminals, where each wireless communication terminal performs group communication in a half-duplex manner via the wireless repeater using pair channels for uplink and downlink. [Means for solving the problem]

[0018] The first invention is a wireless relay system comprising a wireless repeater and a plurality of wireless communication terminals constituting a group, wherein the wireless repeater selects one pair channel from a group of two channels (hereinafter referred to as "pair channels") that are usable as uplink and downlink waves for communication between the wireless repeater and each wireless communication terminal in accordance with the standards formulated based on the Radio Law Enforcement Regulations and the Radio Equipment Regulations, and performs group communication between the wireless communication terminals in a half-duplex manner, wherein the wireless repeater comprises a receiving demodulation unit A, a receiving demodulation unit B, a modulation transmission unit C, and a control unit that controls them, and the receiving demodulation unit A and the The modulation transmission unit C is configured with the aforementioned pair of channels, while the receiver demodulation unit B scans the group of channels available as receiving channels for the receiver demodulation unit A and searches for an available channel. In standby / receive mode, the receiver demodulation unit A and the receiver demodulation unit B are in the ON state, and the modulation transmission unit C is in the OFF state. When group identification information relating to the group is detected and confirmed from the demodulated signal of the receiver demodulation unit A, the system switches to relay mode. In this relay mode, the modulation transmission unit C is in the ON state, and the carrier wave of the transmission channel is modulated with the demodulated signal output by the receiver demodulation unit A. In addition, in the standby / receive mode, if the receiving demodulation unit A receives radio waves with a certain electric field strength or higher for a predetermined time or longer in which it cannot detect and confirm the group identification information from its demodulated signal, the set pair channel of the receiving demodulation unit A and the modulation transmission unit C is changed to a pair channel related to an available channel searched by the receiving demodulation unit B, and the modulation transmission unit C is turned ON to transmit the group identification information and channel change request information. Each wireless communication terminal comprises a receiving demodulation unit D, a modulation transmission unit E and a control unit that controls them, and the receiving demodulation unit D and the modulation The modulating transmitter E is configured with the pair channels set in the receiving demodulation unit A and the modulating transmitter C on the wireless repeater side in an inverse relationship for transmission and reception. In standby mode, the receiving demodulation unit D cycles through the group of channels available as receiving channels. In reception mode, the receiving demodulation unit D is turned ON and the modulating transmitter E is turned OFF, and the demodulated signal output by the receiving demodulation unit D is reproduced as audio. In transmission mode, the receiving demodulation unit D is turned OFF and the modulating transmitter E is turned ON, and the carrier wave of the transmission channel of the modulating transmitter E is modulated with the input audio signal and transmitted.In addition, in the standby mode, when the reception demodulation unit D receives the group identification information and the channel change request information transmitted by the wireless repeater side during its scanning process, it sets the received channel and the channel in a paired channel relationship with respect to it to the reception demodulation unit D and the modulation transmission unit E, respectively. It relates to a wireless relay system characterized by this.

[0019] This first invention relates to a wireless relay system for automatically changing the currently used channel of a group communication network when a wireless repeater receives interfering radio waves. Regarding the determination of interfering radio waves, it is assumed that the group identification information cannot be detected and confirmed from the demodulated signal of the reception demodulation unit A, the radio wave is above a certain electric field strength, and its reception continues for a predetermined time or more. When the radio waves of wireless communication terminals not belonging to the group or other noise sources are at a level that harms the voice call of the group communication and continue for a certain period of time, it is considered that there are interfering radio waves. In this invention, the wireless repeater includes a reception demodulation unit A for original signal reception and a reception demodulation unit B for channel scanning, while the reception demodulation unit D of each wireless communication terminal serves both for signal reception and channel scanning. In the wireless repeater, a free paired channel is searched from the group of channels available as the reception channel of the reception demodulation unit A by the scanning operation of the reception demodulation unit B in the standby / reception mode. In each wireless communication terminal, by the scanning operation of the reception demodulation unit D in the standby mode, it is possible to receive the information transmission radio waves from the wireless repeater that cannot be received on the current set channel when the wireless repeater receives interfering radio waves, and in the reception mode, normal radio wave reception and demodulation are performed on the current set channel. Then, in the wireless repeater, when there is such interfering radio waves with respect to the reception demodulation unit A, the available paired channels previously searched by the reception demodulation unit B are reconfigured to the reception demodulation unit A and the modulation transmission unit C, and group identification information and channel change request information are modulated and transmitted from the modulation transmission unit C through the available channel. On the other hand, on each wireless communication terminal side, the reception demodulation unit D in the standby mode receives and demodulates the group identification information and channel change request information from the wireless repeater during its scanning process, and reconfigures the paired channel related to the received channel to the reception demodulation unit D and the modulation transmission unit E. In that case, although the channels reconfigured to the reception demodulation unit A and the modulation transmission unit C on the wireless repeater side and the channels reconfigured to the reception demodulation unit D and the modulation transmission unit E on each wireless communication terminal side are of course the same available paired channels, the channels have an inverse relationship in terms of transmission and reception between the wireless repeater side and each wireless communication terminal side. As a result, according to the wireless relay system according to the first invention, when the wireless repeater receives interfering radio waves, the paired channels used for group communication can be automatically changed to other available paired channels, enabling half-duplex wireless communication in a good state with a high SN ratio that excludes the influence of the interfering radio waves.

[0020] In the wireless repeater of the wireless communication system according to the first invention, when the reception demodulation unit A receives radio waves with a certain electric field strength or more for a predetermined time or more and cannot confirm the group identification information from its demodulated signal, and when a plurality of available paired channels are detected in one scanning process by the reception demodulation unit B immediately before the reception for the predetermined time or more is detected, it is desirable that the available paired channel with the largest frequency separation from the non-available paired channel be reconfigured to the reception demodulation unit A and the modulation transmission unit C, and the modulation transmission unit C be controlled to transmit the group identification information and channel change request information.

[0021] The paired channels are defined by the standard specifications of the wireless equipment of various wireless stations, and in each standard specification, a number of available paired channels are prepared in ascending order at a predetermined frequency interval. Therefore, depending on conditions such as the location of the wireless repeater, a large number of empty pair channels are often detected during the single-cycle scan process in the receiver demodulation unit B. On the other hand, for example, the frequency spacing between each pair of channels in the standard specification in Non-Patent Document 1 mentioned above is 12.5 kHz for channels 1 to 18 and 25.0 kHz for channels 32 to 40, as shown in Figure 3. This assumes that interference will not occur between paired channels with different channel numbers. However, if another group's wireless communication system is operating in a nearby area using channels with adjacent channel numbers, if there is a strong noise source such as a microwave oven in a nearby restaurant, or if illegal radio stations are operating on nearby frequencies or abnormal radio wave propagation occurs, radio interference may occur even if the channel numbers are different, causing problems with voice communication. Therefore, in the wireless repeater according to the first invention, if the receiving demodulation unit B detects multiple empty pair channels during its one-cycle scan process immediately before the receiving demodulation unit A detects the reception of interfering radio waves, the receiving demodulation unit A and the modulation transmission unit C are changed to select the empty pair channel with the largest frequency separation from the non-empty pair channel (including the currently set pair channel) from among those empty pair channels, thereby selecting an empty pair channel that is as unaffected by radio interference as possible. The wireless repeater then uses the modulation transmission unit C to transmit group identification information and channel change request information through its selected available channel, and the transmit / receive channels on each wireless communication terminal are also changed to that available channel. Therefore, it becomes possible to more effectively eliminate the effects of interfering radio waves and realize half-duplex wireless communication with a high signal-to-noise ratio without radio interference.

[0022] Furthermore, if the wireless repeater of the wireless communication system according to the first invention selects an available pair channel from among the available pair channels, taking into account the frequency separation from the non-available pair channels, and changes the settings of the receiving demodulation unit A and the modulation transmission unit C accordingly, and if it is necessary to perform carrier sensing using the receiving demodulation unit A prior to the transmission operation of the modulation transmission unit C, it is desirable to control the system to select available pair channels in order of decreasing frequency separation from the non-available pair channels and perform carrier sensing.

[0023] In the aforementioned wireless repeater, except for those with a transmitting antenna power of 1mW or less, carrier sensing must be performed prior to transmission. However, since the receiver demodulator B performs carrier sensing on an empty pair channel detected in a single scan immediately before detecting the reception of interfering radio waves, it should be idle in most cases. However, in a congested network environment, even in the short time before carrier sense is performed, the carrier sense results may become busy for reasons such as other groups starting to use the available channels that are the target of carrier sense. Taking these circumstances into consideration, this wireless repeater selects an available pair channel for the next carrier sense when the carrier sense result indicates transmission is impossible. This selection criteria is based on the degree of frequency separation from the currently configured pair channel, ensuring that an available pair channel less susceptible to interference is selected.

[0024] The second invention is a wireless relay system comprising a wireless repeater and a plurality of wireless communication terminals constituting a group, wherein the wireless repeater selects one pair channel from a group of two channels (hereinafter referred to as "pair channels") that are usable as uplink and downlink waves for communication between the wireless repeater and each wireless communication terminal in accordance with the standards formulated based on the Radio Law Enforcement Regulations and the Radio Equipment Regulations, and performs group communication between the wireless communication terminals in a half-duplex manner, wherein the wireless repeater comprises a receiving demodulation unit A, a receiving demodulation unit B, a modulation transmission unit C, and a control unit that controls them, and the receiving demodulation unit A and the modulation transmission unit C is configured with the aforementioned pair channel, while the receiver / demodulator B cycles through the group of channels available as receiving channels for the receiver / demodulator A. In standby / receive mode, the receiver / demodulator A and the receiver / demodulator B are in the ON state, and the modulation / transmitting unit C is in the OFF state. When group identification information relating to the group is detected and confirmed from the demodulated signal of the receiver / demodulator A, the system switches to relay mode. In relay mode, the modulation / transmitting unit C is in the ON state, and the carrier wave of the transmission channel is modulated with the demodulated signal output by the receiver / demodulator A and transmitted. In addition, the standby / receive mode In the D, when the receiving demodulation unit B receives the group identification information and channel change request information transmitted by any of the wireless communication terminals during its cyclic scanning process, it sets the receiving channel and the channel that is paired with it to the receiving demodulation unit A and the modulation transmission unit C, respectively, and transmits the group identification information and the channel change request information from the modulation transmission unit C. Each wireless communication terminal is equipped with a receiving demodulation unit D, a modulation transmission unit E and a control unit that controls them, and the receiving demodulation unit D and the modulation transmission unit E are on the wireless repeater side The pair channels set in the receiver / demodulator A and the modulated transmitter C are set in an inverse relationship for transmission and reception. In standby mode, the receiver / demodulator D scans through the group of channels available as reception channels and searches for an empty channel. In reception mode, with the receiver / demodulator D ON and the modulated transmitter E OFF, the demodulated signal output by the receiver / demodulator D is reproduced as audio. In transmission mode, with the receiver / demodulator D OFF and the modulated transmitter E ON, the carrier wave of the transmission channel of the modulated transmitter E is modulated with the input audio signal and transmitted.Furthermore, in the standby mode, if the receiving demodulation unit D receives radio waves with a certain electric field strength or higher for a predetermined period of time or longer in which it cannot detect and confirm the group identification information from the demodulated signal, the receiving demodulation unit D changes the set pair channel of the receiving demodulation unit D and the modulation transmission unit E to a pair channel relating to an available channel searched by the receiving demodulation unit D, and turns on the modulation transmission unit E to transmit the group identification information and the channel change request information. On the other hand, if the receiving demodulation unit D receives the group identification information and the channel change request information transmitted by the wireless repeater during its cyclic scanning process, it sets the receiving channel and the channel that is its pair channel to the receiving demodulation unit D and the modulation transmission unit E, respectively.

[0025] This second invention relates to a wireless relay system for automatically changing the channel used in a group communication network when the wireless communication terminal, rather than the wireless repeater, receives interference. In this invention, as in the first invention, the wireless repeater comprises a receiving demodulation unit A, a receiving demodulation unit B, and a modulation transmission unit C, and each wireless communication terminal comprises a receiving demodulation unit D and a modulation transmission unit E. However, in this second invention, the receiver / demodulator D has not only a function to scan the channel group cyclically as in the first invention, but also a function to search for available channels. The receiver / demodulator D of any one of the wireless communication terminals receives an interfering radio wave, and that wireless communication terminal sets the available pair channel searched by the receiver / demodulator D to the receiver / demodulator D and the modulation / transmission unit F, and transmits group identification information and channel change request information. On the other hand, the wireless repeater is responsible for propagating channel change requests to wireless communication terminals other than the aforementioned first wireless communication terminal. When the receiving demodulation unit B receives group identification information and channel change request information during its cyclic scanning process, it changes the pair channel related to that received channel to the receiving demodulation unit A and the modulation transmission unit C, and also transmits the group identification information and channel change request information from the modulation transmission unit C. Thereafter, when each wireless communication terminal receives group identification information and channel change request information from a wireless repeater during the cyclic scanning process of the receiver / demodulator D, the receiving channel and the channel that is paired with it are set in the receiver / demodulator D and the modulation / transmission unit E, respectively, as in the first invention. As a result, both the wireless repeater and each wireless communication terminal can automatically switch the pair channel used for group communication from one with interference to another available pair channel, enabling half-duplex wireless communication under good conditions with a high signal-to-noise ratio. Furthermore, the group identification information and channel change request information from the wireless repeater will also be received by the receiving / demodulating unit D in wireless communication terminals where the receiving / demodulating unit D and modulation / transmitting unit E have already been set to an empty pair channel due to interference. In that case, the wireless communication terminal may also need to reconfigure an available pair channel, but this can be ignored because there is direct reception at the receiver / demodulator D.

[0026] In each wireless communication terminal of the wireless communication system according to the second invention, when the receiving demodulation unit D receives radio waves with a certain electric field strength or greater for a predetermined period of time or longer in which the group identification information cannot be confirmed from the demodulated signal, and when multiple empty pair channels are detected in the one-cycle scanning process by the receiving demodulation unit E immediately before the detection of such reception for a predetermined period of time or longer, it is desirable that the receiving demodulation unit D and the modulation transmission unit E be changed to the empty pair channel with the largest frequency separation from the non-empty pair channels, and that the modulation transmission unit E be controlled to transmit the group identification information and channel change request information.

[0027] Furthermore, in the wireless communication terminal of the wireless communication system according to the second invention, when carrier sensing is performed using the receiving demodulation unit D prior to the transmission operation of the modulation transmission unit E, it is desirable to control the system to select available pair channels in order of decreasing frequency separation from non-available pair channels and perform carrier sensing.

[0028] The selection method for these available pair channels is similar to the control used when a wireless repeater in the first invention receives an interfering radio wave, thereby more effectively eliminating the effects of interfering radio waves and realizing half-duplex wireless communication with a high signal-to-noise ratio without radio interference. [Effects of the Invention]

[0029] The present invention relates to a wireless relay system comprising a wireless repeater and a group of wireless communication terminals constituting a single group, in which a pair channel is selected from a group of pair channels that can be used for uplink and downlink communication between the wireless repeater and each wireless communication terminal according to the standards formulated based on the Radio Law Enforcement Regulations and the Radio Equipment Regulations, and which performs group communication between wireless communication terminals using a half-duplex method. In the event that the wireless repeater or wireless communication terminal receives interference, the system can change the currently set pair channel to a pair channel selected from a group of available pair channels that have been searched in advance by a cyclic scan of the group of pair channels, thereby more effectively eliminating the effects of interference and realizing half-duplex wireless communication with a high signal-to-noise ratio without radio interference. Furthermore, although the frequency bandwidth of the source of interference may be wide, a more favorable effect can be obtained by selecting the available pair channel with the greatest frequency separation from the non-available pair channel (including the currently set pair channel that has received interference) from among the multiple available pair channels. [Brief explanation of the drawing]

[0030] [Figure 1] This is a functional block diagram of a wireless repeater applied to an embodiment of the wireless repeater system of the present invention. [Figure 2] This is a functional block diagram of a wireless communication terminal applied to an embodiment of the wireless relay system of the present invention. [Figure 3] This table shows the paired channel groups used in the wireless relay system of the embodiment (a total of 27 pairs as shown in Tables 3-2 and 3-4 of Non-Patent Document 1). [Figure 4] This is a diagram of the communication frame format used in the wireless relay system of the embodiment. [Figure 5] This is a wireless relay network diagram according to Embodiment 1 (standby state on CH1). [Figure 6] This is a diagram of the wireless relay network according to Embodiment 1 (communication status on CH1). [Figure 7] This is a diagram of the wireless relay network according to Embodiment 1 (showing the state of interference radio wave generation to the wireless repeater). [Figure 8] This is a wireless relay network diagram according to Embodiment 1 (showing the state after a channel change request has been sent from the wireless relay to each wireless communication terminal). [Figure 9] This is an operation flowchart of the wireless repeater in Embodiment 1. [Figure 10] This is an operation flowchart for each wireless communication terminal in Embodiment 1. [Figure 11] This is a diagram of the wireless relay network according to Embodiment 1 (standby state after channel change settings have been made on the wireless repeater and each wireless communication terminal). [Figure 12] This is a wireless relay network diagram (communication status on CH2) according to Embodiment 1. [Figure 13] This is a diagram of the wireless relay network according to Embodiment 2 (showing the state of interference radio wave generation to wireless communication terminals). [Figure 14] This is a diagram of a wireless relay network according to Embodiment 2 (in a state where a channel change request has been sent from a wireless communication terminal to a wireless relay device). [Figure 15] This is an operation flowchart for each wireless communication terminal in Embodiment 2. [Figure 16] This is an operation flowchart of the wireless repeater in Embodiment 2. [Figure 17] This is a wireless relay network diagram according to Embodiment 2 (showing the state after a channel change request has been sent from the wireless relay to each wireless communication terminal). [Figure 18] This is a wireless relay network diagram according to Embodiment 2 (standby state on CH2). [Figure 19] This is a wireless relay network diagram (communication status on CH2) according to Embodiment 2. [Figure 20]This is a diagram of a conventional wireless relay network (standby state on CH1). [Figure 21] This is a diagram of a conventional wireless relay network (communication status on CH1). [Figure 22] This is a diagram of a conventional wireless relay network (showing the state of interference generated by wireless repeaters). [Modes for carrying out the invention]

[0031] Hereinafter, embodiments of the wireless relay system of the present invention will be described in detail with reference to Figures 1 to 19. However, in this embodiment, the wireless repeater and the wireless communication terminal are assumed to conform to the wireless equipment for specified low-power radio stations / wireless telephones described in Non-Patent Document 1.

[0032] <Configuration of a wireless repeater> The wireless repeater 50 according to this embodiment has the configuration shown in Figure 1. In the figure, 11 is the receiving antenna, 12 is the amplifier, RX01 and RX02 are the receiving demodulation units, 13 is the signal switching unit, TX01 is the modulation transmission unit, 14 is the amplifier, 15 is the transmitting antenna, 16 is the system control unit, 17 is the operation unit, and 18 are various indicator lamps. The operation of the entire wireless repeater 50 is controlled by the system control unit 16. The receiver / demodulator RX01 and the modulated transmitter TX01 are controlled and set to uplink and downlink channels, respectively. The receiver / demodulator RX01 demodulates the signal for the set channel from the radio wave signal received by the receiving antenna 11 and outputs it to the modulated transmitter TX01. Meanwhile, the modulated transmitter TX01 modulates the carrier signal for the set channel with the demodulated signal input from the receiver / demodulator RX01, power-amplifies the modulated signal, and transmits radio waves from the transmitting antenna 15.

[0033] Here, each channel set in the receiver / demodulator RX01 and the modulation / transmitting unit TX01 is a pair channel related to one of the channel numbers in Figure 3. In each of the embodiments described below, the channel on the H-band side is set in the receiver / demodulator RX01, and the channel on the L-band side is set in the modulation / transmitting unit TX01. Therefore, the wireless repeater 50 uses the H-band channel for the uplink and the L-band channel for the downlink to perform relay communication using the pair channel.

[0034] On the other hand, the receiver / demodulator RX02 is controlled to continuously scan all channels on the H-band side (the same band side as the receiver / demodulator RX01) as shown in Figure 3. The purpose of using the cyclic scanning function of the receiver / demodulator RX02 differs between Embodiment 1 and Embodiment 2 below. In Embodiment 1, it is used to check for available pair channels during the cyclic scanning process of the H-band group, and for the system control unit 53 to update and store this information in its internal memory. In Embodiment 2, it is used to receive group identification information and channel change request signals transmitted from the wireless communication terminal 60 on a channel different from the channel set by the receiver / demodulator RX01 (a changed and set channel).

[0035] The control unit 17 allows users to turn the power on / off, select the group communication mode, select available pair channels, and perform button operations for other setting information. Various indicator lamps light up / flash / turn off to indicate the mode setting status, battery (not shown) depletion status, etc., and the system control unit 16 also manages and controls these functions.

[0036] <Configuration of wireless communication terminal> The wireless communication terminals 60a, 60b, and 60c according to this embodiment have the configuration shown in Figure 2. In the figure, 20 is the transmitting and receiving antenna, 21 is the antenna switching unit, 22 is the amplifier, RX11 is the receiving and demodulating unit, 23 is the amplifier, 24 is the speaker (or earphone), 25 is the microphone, 26 is the amplifier, TX11 is the modulation transmitter, 27 is the amplifier, 28 is the system control unit, 29 is the operation unit, and 30 is the liquid crystal display unit. The overall operation of the wireless communication terminals 60a, 60b, and 60c is controlled by the system control unit 28.

[0037] In the receiving systems of 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. The receiving demodulation unit RX11 demodulates the signal related to the set channel, and the demodulated signal is amplified by the amplifier 23 and output as audio from the speaker 24. In this receiving mode, the receiver demodulator RX11 and the modulation transmitter TX11 are set to paired channels. However, these channels have an inverse relationship in terms of transmission and reception with respect to the paired channels set on the receiver demodulator RX01 and the modulation transmitter TX01 on the wireless repeater 50 side. In each of the embodiments described below, the receiver demodulator RX11 is set to the channel on the L-band side, and the modulation transmitter TX11 is set to the channel on the H-band side.

[0038] On the other hand, in standby mode, the receiver demodulator RX11 is controlled to cycle through all channels on the L-band group side as shown in Figure 3. The purpose of using the cyclic scanning function of the receiving demodulation unit RX11 differs between Embodiment 1 and Embodiment 2 below. In Embodiment 1, it is used to receive group identification information and channel change request signals 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 intended use, it is used to check for available pair channels by cyclic scanning of the H-band group, and to allow the system control unit 67 to update and store the scan information in its internal memory.

[0039] In the transmission systems of wireless communication terminals 60a, 60b, and 60c, the audio signal input from the microphone 25 is amplified by the amplifier 26, the modulation transmission unit TX11 modulates the carrier signal of the set channel with the amplified audio signal, the modulated signal is power amplified by the amplifier 27, and radio waves are transmitted from the transmitting antenna 20 via the antenna switching unit 21.

[0040] Furthermore, the antenna switching unit 21 needs to be switched according to the change in transmission / reception mode. Also, power ON / OFF, selection of various communication modes, selection of available pair channels, and other settings can be performed by operating the buttons and dials on the operation unit 29. In addition, the liquid crystal display unit 30 displays the mode setting status, the channel in use, and the battery (not shown) depletion status, and the system control unit 28 also manages and controls these functions.

[0041] <Communication frame format> Figure 4 is an example of a communication frame format diagram used in group communication in the embodiment described below. On the transmitting side, a modulated wave is transmitted using MSK (Minimum Shift Keying) or the like, based on the baseband signal of the audio signal section incorporated into the format. On the receiving side, the received signal related to this modulated wave is demodulated to reconstruct 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 operation control. Furthermore, the data payload contains self-identification information, group identification information, and transmission / reception channel information, and can also include a channel change request signal if interference is detected in the wireless repeater 50 or wireless communication terminals 60a, 60b, or 60c. The communication frame format used in the following embodiment has a cycle of 80 msec and consists of 386 bits.

[0042] <Embodiment 1> This embodiment 1 relates to the operation and system procedure of the repeater 50 and the communication terminals 60a, 60b, and 60c when the repeater 50 receives an interfering radio wave and changes the pair channel used for group communication to another available pair channel, in a wireless communication system that configures a group communication network using a half-duplex method with the aforementioned wireless repeater (hereinafter abbreviated as "repeater") 50 and three wireless communication terminals (hereinafter abbreviated as "communication terminals") 60a, 60b, and 60c.

[0043] The wireless relay network diagram in Figure 5 shows that in the group communication network, the transmit / receive channel for group communication is set to pair channel CH1, and the repeater 50 and each communication terminal 60a, 60b, and 60c are in a standby state. Here, in all wireless relay network diagrams from Figure 5 onward (excluding Figures 20 to 22), the functional blocks RX01, RX02, and TX01 included in the repeater 50 represent two receiving / demodulating units and a modulation / transmitting unit corresponding to their codes in Figure 1, and the functional blocks RX11 and TX11 included in the communication terminals 60a, 60b, and 60c represent the receiving / demodulating unit and a modulation / transmitting unit corresponding to their codes in Figure 2. Furthermore, regarding "CHi-X" (i=1,2, X=L,H) appended via ":" to each of the aforementioned symbols related to the receiving demodulation unit and the modulation transmission unit, "CHi" corresponds to the channel number related 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 for all channels on the H-band side in Figure 3 for the receiving demodulation unit RX02 of the repeater 50, and the cyclic scanning state for all channels on the L-band side in Figure 3 for the receiving demodulation unit RX11 of the communication terminals 60a, 60b, and 60c. Furthermore, in the functional blocks of the repeater 50 and communication terminals 60a, 60b, and 60c, those without diagonal lines indicate the ON state, while those with diagonal lines indicate the OFF state.

[0044] Figure 6, a wireless relay network diagram, shows the relay communication state via the relayer 50 when, starting from the standby state in Figure 5, communication terminal 60a becomes the transmitting side and communication terminals 60b and 60c become the receiving sides. When communication terminal 60a transmits a voice call signal on channel CH1-H with the receiver / demodulator RX11 in the OFF state and the modulation / transmission unit TX11 in the ON state, repeater 50 receives and demodulates the radio waves with the receiver / demodulator RX01, switches the modulation / transmission unit TX01 from the OFF state to the ON state, and transmits a modulated signal on channel CH1-L, modulated with the carrier wave signal. Meanwhile, when standby communication terminals 60b and 60c detect the relayed radio waves during the cyclic scanning process of the receiver / demodulator RX11, they immediately set the receiver / demodulator RX11 to channel CH1-L and demodulate the received signal to reproduce the voice through speaker 24.

[0045] Figure 6 shows the case where communication terminal 60a becomes the transmitting terminal. However, regardless of whether communication terminals 60a, 60b, or 60c becomes the transmitting terminal, group communication using a half-duplex scheme with channel CH1-H as the uplink and channel CH1-L as the downlink is performed similarly via the repeater 50. However, since this is group communication, the 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 after confirming that the data payload of the received and demodulated signal contains G-ID: "01", they proceed with demodulating the voice signal. Furthermore, in this embodiment, since the network communication is based on the specified low-power radio station / wireless telephone equipment / standard specifications described in Non-Patent Document 1, the communication terminals 60a, 60b, 60c and the repeater 50 always perform carrier sensing prior to radio wave transmission and transmit only after confirming that they are not receiving radio waves exceeding a predetermined field strength from other radio stations, etc.

[0046] Incidentally, the system control unit 16 of the repeater 50 controls the receiving channel of the receiving demodulation unit RX02 and cycles through all 27 channels on the H-band side in Figure 3 to check whether each channel is available or not, and constantly stores the confirmation information for each cycle in the built-in memory using a ring buffer method. Specifically, as illustrated in the right column of Figure 3, the system creates a scanning information table by setting the flag OFF for channels that are empty due to no radio wave reception above a predetermined level, and conversely, setting the flag ON for channels that have radio wave reception above a predetermined level. This operation is performed on all 27 channels in the H-band group as one cycle, and the table is sequentially updated and stored in the internal memory.

[0047] Furthermore, since the cyclic scanning in this case is not the implementation of carrier sensing, it is not subject to the constraint in the article on carrier sensing on pages (1-10) of Non-Patent Document 1, namely, that "200 msec should be taken for each channel to determine whether the value of the received input power at the feed line input point is -96 dBm or higher." There is no difference in determining whether the value of the received input power is above a predetermined level, but if there is no obligation for the time condition (200 msec), then in practice, 25 msec per channel is sufficient. Therefore, even for a cyclic scan of all 27 channels, the time required for one cyclic scan is only about 675 msec (= 25 msec × 27).

[0048] In this embodiment, the receiving demodulation unit RX02 scans 27 channels. However, if the pair channels used in the wireless relay network are limited, then naturally only those limited channels (for example, 10 channels) will be scanned, and the scan time for one cycle will be even shorter.

[0049] Incidentally, Figure 7 shows the case where the repeater 50 is receiving interference in the standby state (Figure 6), and here it shows the state in which the repeater 50 receives a voice call signal from a communication terminal 70 belonging to another group (G-ID: "02") using radio waves on channel CH1-H. In that case, if the relay 50 relays the aforementioned jamming radio signal, communication between the communication terminals 60a, 60b, and 60c of the group (G-ID: "01") that uses the relay 50 to form a communication network will become impossible. Therefore, the relay 50 resolves this problem by executing the procedure shown in the flowchart of Figure 9.

[0050] First, when the receiver / demodulator RX01 of the repeater 50 receives a radio wave with a predetermined electric field strength or higher while in standby mode, the system control unit 16 checks the data payload of the received / demodulated signal obtained from the receiver / demodulator RX01 and determines whether or not the group code "01" as the G-ID can be detected (S1-S4). In this case, the electric field strength for radio wave reception by the receiver / demodulator RX01 should be determined by considering whether or not it interferes with voice communication. Alternatively, as with the carrier sense specification conditions, the criterion may be whether or not the value of the received input power is -96 dBm or higher at the feed line input point.

[0051] In steps S1 to S4, if the electric field strength related to radio wave reception by the receiver / demodulator RX01 is smaller than the above standard, it is not considered an interfering radio wave and remains in standby mode (S1, S2: N → S1). Also, if GID: "01" is detected from the data payload of the received / demodulated signal, it is considered that radio waves transmitted from communication terminals 60a, 60b, and 60c within the group have been received, and since it is received by the receiver / demodulator RX01, it is nothing more than the reception of radio waves for normal voice 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 when the communication ends (S4: Y → S5, S6 → S1).

[0052] On the other hand, if GID:"01" is not detected, it is possible that interference is occurring, so the built-in interval timer is started (S4:N→S7) and it is checked whether reception of the radio wave continues while maintaining the field strength (S8,S9). If reception of the radio wave is interrupted before the predetermined time set in the interval timer has elapsed, the timer is reset and the system returns to standby mode (S7→S8, S9→S8:N→S10→S1). If a timeout occurs, the timer is reset, and the system proceeds to the procedure for changing the channel used for subsequent wireless relay networks (S9:Y→S11~S18).

[0053] In this context, the interfering radio waves are assumed to be from a communication terminal 70 of another group, as shown in Figure 7. However, this does not exclude interfering radio waves from other radio sources. Rather, in order to target radio wave reception from sources other than communication terminals 60a, 60b, and 60c belonging to the group, the only condition for identifying interfering radio waves is that GID: "01" is not detected (S4). Furthermore, if the interfering radio waves do not persist for a predetermined time set in the interval timer (for example, 1 second), the system maintains the channel used by the wireless relay network (S7~S10→S1), thus avoiding frequent channel changes caused by sudden interfering radio waves that do not significantly affect calls.

[0054] The change on the repeater 50 side regarding the channels used in the wireless relay network is as follows: First, to prevent signals caused by interfering radio waves from being relayed, the receiver demodulator RX01 is turned OFF and the signal switching unit 13 is switched to the CCR input side (S11). Then, the currently set pair channels (CH1-H and CH1-L) of the receiver demodulator RX01 and the modulation transmission unit TX01 are changed to an available pair channel selected based on the status information of each pair channel obtained by the previous cyclic scan by the receiver demodulator RX02. In other words, the receiver demodulator RX02, immediately before the timeout, selects the empty pair channel with the greatest frequency separation from the non-empty pair channel among the empty pair channels detected by a single cycle scan of the H-band group in Figure 3, and changes the currently set pair channels (CH1-H and CH1-L) of the receiver demodulator RX01 and the modulation transmitter TX01 to the selected pair channel (S12, S13).

[0055] Specifically, assuming that the system control unit 16 creates a scan information table in its internal memory based on the demodulated signal from one scan cycle immediately before the timeout by the receiver / demodulator RX02, in which OFF empty pair channels and ON non-empty pair channels are detected, as shown in the right column of Figure 3's radio wave reception flags, and the channel number of the currently set pair channel for the receiver / demodulator RX01 and the modulation / transmitter TX01 is 6 (=CH1), and there is interference on that pair channel, then the empty pair channel with the greatest frequency separation from the non-empty pair channel in the scan information table corresponds to channel number 32 (=CH2), and that empty pair channel (CH2-H and CH2-L) will be changed to the settings for the receiver / demodulator RX01 and the modulation / transmitter TX01.

[0056] The method for finding "the free pair channel with the greatest frequency separation from the non-free pair channel" is as follows: (1) In the column for radio wave reception flags, if there are ONs on both sides of OFF or at both ends of a continuous section of OFF, determine the interval of the channel frequencies related to the ONs on both sides or at both ends. (2) In the column for radio wave reception flags, if the flag for channel number 1 is OFF, determine the interval between the channel frequency of the smallest channel number for which the flag is ON and the channel frequency of channel number 1. (3) In the column for radio wave reception flags, if the flag for channel number 40 is OFF, determine the interval between the channel frequency of channel number 40 and the channel frequency of the highest channel number for which the flag is ON. (4) Compare half of the interval obtained in (1), the interval obtained in (2), and the interval obtained in (3). If the value in (1) is the maximum, select the pair channel relating to the OFF channel sandwiched between the ON channels, or the pair channel relating to the channel with the frequency closest to the summation average of the ON channel frequencies at both ends. If the value in (2) is the maximum, select the pair channel of channel number 1. If the value in (3) is the maximum, select the pair channel of channel number 40. Based on the radio wave reception flags in the right column of Figure 3, the corresponding pair channel determined by algorithm (4) is channel number 32 (=CH2) as described above.

[0057] Figure 8 shows the state in which the receiver / demodulator RX01 and the modulation / transmission unit TX01 of the repeater 50 have been changed to an available pair channel (CH2-H and CH2-L). As a result, the repeater 50 has moved to the pair channel of channel number CH2 and is no longer affected by interference from the communication terminal 70. However, the communication terminals 60a, 60b, and 60c are still set to the channel used by the previous wireless relay network (CH1). Therefore, the repeater 50 needs to send a GID: "01" and a channel change request signal (hereinafter referred to as "CCR") to the communication terminals 60a, 60b, and 60c to set the pair channel of channel number CH2.

[0058] Therefore, the repeater 50 will transmit the CCR by turning on the modulation transmitter TX01, which has been set to CH2-L, but prior to transmission, it is necessary to perform carrier sensing related to the paired channels (CH2-H, CH2-L) using the receiver demodulation unit RX01 (S14). In that case, since the pair channel of channel number CH2 was confirmed to be free in the previous cycle scan, the carrier sense result should mostly indicate an idle state and that transmission is possible. However, if, by chance, interference signals related to the pair channel of channel CH2 occurred after the aforementioned cycle scan, it may result in a busy state and transmission may be impossible.

[0059] Therefore, when the carrier sense results in a busy state, the carrier sense is re-executed by selecting the free pair channel with the second largest frequency separation from the non-free pair channel in the scan information table (corresponding to channel number 9 in the scan information table) (S12~S15:N→S16→S13). Furthermore, for a pair of channels whose channel number has become busy, the radio wave reception flag is subsequently changed to the ON state, and the separation degree is compared and determined. The same process is repeated thereafter to select the available pair of channels with the mth largest separation degree. However, it is extremely rare to select a channel from the third channel onwards.

[0060] If the carrier sense result is idle, the repeater 50 turns on the modulation transmitter TX01 as shown in Figure 8, incorporates GID:"01" and CCR into the data payload of the communication frame, and transmits the voice signal portion as dummy data for frame length adjustment, repeatedly for a certain period of time (for example, 1 second) on the channel (CH2-L) of the modified modulation transmitter TX01 (S15→S17). Furthermore, once the transmission of that signal is complete, 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 receiving demodulation unit RX01, returning to the standby state (S18 → S1). Figure 8 shows that the first carrier sense is idle in the pair channel (CH2-L) with the largest frequency separation from the non-empty pair channel, and the modulation transmitter TX01 transmits GID: "01" and CCR on that channel (CH2-L).

[0061] Meanwhile, at this stage, each communication terminal 60a, 60b, and 60c is in standby mode, and the modulation transmission unit TX11 is in the OFF state and remains on the previously set channel (CH1-L). However, the receiving demodulation unit RX11 is scanning all channels on the L-band side in Figure 3, and the GID: "01" and CCR transmitted from the repeater 50 are received by the receiving demodulation unit RX11 of each communication terminal 60a, 60b, and 60c during the scanning process and detected from the demodulated signal.

[0062] Figure 10 shows the procedure for changing the transmit / receive channel settings on each communication terminal 60a, 60b, and 60c. First, in each communication terminal 60a, 60b, and 60c, if the receiving demodulation unit RX11 receives a radio wave with a predetermined electric field strength or higher during the cyclic scanning process while in standby mode, it temporarily stops the cyclic scanning on that receiving channel (S21-S23).

[0063] Here, regarding the cyclic scanning of the receiver / demodulator RX11 of each communication terminal 60a, 60b, and 60c, similar to the receiver / demodulator RX02 of the repeater 50, all 27 channels on the L-band side in Figure 3 are scanned at a rate of 675 msec per cycle, and for each individual channel, it is determined at a rate of approximately 25 msec whether or not a radio wave above a predetermined level is received. In that case, as described above, the communication frames from the repeater 50 are transmitted in 80 msec in one cycle (386 bits), and approximately 8.44 frames (=675 / 80) are continuously received during one cycle scan in the receiver demodulator RX11 of each communication terminal 60a, 60b, and 60c. Therefore, each communication terminal 60a, 60b, and 60c can confirm if a radio wave above a predetermined level is received during the cyclic scanning process of the receiver demodulator RX11, stop the cyclic scanning on that receiving channel, and detect GID: "01" and CCR from the data payload of the demodulated communication frame (S23-S26).

[0064] Furthermore, if GID:“01” is detected in the data payload of the communication frame, it is none other than a communication frame received from the group's repeater 50 (S25:Y). If CCR is also detected, it means that a request for a network channel change has been made from the repeater 50 that has received interference as described above (S26:Y). Therefore, each communication terminal 60a, 60b, and 60c changes the modulation transmission unit TX11 to a channel that is paired with the scan stop channel of the receiving demodulation unit RX11 where the CCR was detected (S27). Furthermore, although the receiver demodulator RX11 is in a scan-stopped channel, it restarts the cyclic scan and returns to the standby state (S28 → S21).

[0065] 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), then as shown in Figure 11, the receiver demodulator RX01 and modulation transmitter TX01 of the repeater 50 are set to pair channels (CH2-H, CH2-L), and the receiver demodulator RX02 is in a cyclic scan state. In addition, the modulation transmitter TX11 of each communication terminal 60a, 60b, and 60c is set to channel (CH2-H), and the receiver demodulator RX11 is in a cyclic scan state, and the group communication network is in a standby state.

[0066] Therefore, as shown in Figure 12, when any of the communication terminals 60a, 60b, or 60c (communication terminal 60a in the figure) transmits a voice call signal including GID: "01" on the uplink channel (CH2-H) from its modulation transmitter TX11, the repeater 50 receives and relays it and transmits it on the downlink channel (CH2-L). Meanwhile, the other communication terminals (60b, 60c) receive and demodulate the radio waves at the scanning stage of channel (CH2-L) in their respective receiving and demodulating units RX11, stop the cyclic scanning on that channel, and receive, demodulate, and reproduce the voice signals of the subsequent communication frames.

[0067] As a result, in the standby state (Figure 5) where the network channel for group communication using half-duplex between each communication terminal 60a, 60b, and 60c via the repeater 50 is the pair channel with channel number CH1, if there is interference from radio waves to the repeater 50 (Figure 7), the network channel is automatically changed to the pair channel with channel number CH2 (Figure 11), and the system transitions to a state where group communication is possible without being affected by interference from radio waves (Figure 12).

[0068] In step S22 of Figure 10, if the receiver demodulator RX11 does not receive radio waves with a predetermined field strength or higher (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 modulation transmitter TX11 is turned ON. After carrier sensing is performed, 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 modulation transmitter TX11 is turned OFF to return to the standby state (S22:N→S30:Y→S31~S34→S21).

[0069] Furthermore, if GID: "01" is detected in steps S25 and S26 of Figure 10 but CCR is not detected, this is nothing more than normal reception via the repeater 50 in the group communication network. In this case, the mute setting of the amplifier 23 is released, the call signal received on the receiving channel of the receiver demodulator RX11 (the channel where the cyclic scan was stopped in step S23) is demodulated and the voice is played back. When the communication ends, the amplifier 23 is muted, and the cyclic scan of the receiver demodulator RX11 is restarted to return to the standby state (S25:Y → S26:N → S35~S38 → S21).

[0070] Furthermore, if GID:“01” is not detected in step S25, it corresponds to the case where communication terminals 60a, 60b, and 60c are receiving interfering radio waves, and the procedure proceeds to the operation shown in Figure 15 in Embodiment 2 below (S25:N→A→Figure 15→B→S21).

[0071] <Embodiment 2> This second embodiment relates to a wireless communication system that, like the first embodiment, configures a group communication network using a half-duplex method with the repeater 50 and communication terminals 60a, 60b, and 60c. However, it relates to the operation of the repeater 50 and communication terminals 60a, 60b, and 60c and the system procedure when changing the pair channel used for group communication to another available pair channel when any of the communication terminals 60a, 60b, or 60c receives an interfering radio wave.

[0072] Figure 13 shows the case where there is interference from radio waves to the communication terminal 60a in the standby state of Figure 5, and it shows the state in which the communication terminal 60a receives a voice call signal from another group (GID: "02") communication terminal 80 on radio waves of channel (CH1-L). Here, the communication terminal 80, which is the source of the interfering radio waves, has its transmission and reception channels reversed compared to the communication terminal 70 in Embodiment 1. However, in wireless relay systems where control information is intermittently transmitted and received between multiple relays, the transmission and reception channels are often set to be reversed between adjacent relays. When a communication terminal belonging to the network of one adjacent relay enters the network area of ​​the other relay, the relationship becomes similar to that of the communication terminal 80 in Embodiment 2. In that case, since there is interference on the transmission channel (CH1-H) of the communication terminal 60a and the paired channel (CH1-L), carrier sensing will result in a busy state, and the communication terminal 60a will not be able to transmit.

[0073] In the state shown in Figure 13, the interference signal is received and demodulated during the cyclic scanning process of the receiver / demodulator RX11 in the communication terminal 60a. 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 first embodiment) and in Figure 15. First, as described in Embodiment 1, the receiver / demodulator RX11 of each communication terminal 60a, 60b, and 60c scans all 27 channels on the L-band side in Figure 3 at a rate of 675 msec per cycle. For each individual channel, it determines whether a radio wave of a predetermined level or higher has been received at a rate of approximately 25 msec. When the receiver / demodulator RX11 of the communication terminal 60a receives a radio wave of a predetermined electric field strength or higher during the cyclic scanning process, it temporarily stops the cyclic scanning on that receiving channel (Figure 10: S21~S23).

[0074] Here, if GID:“01” is detected in the data payload of the communication frame demodulated by the receiving demodulator RX11, which has stopped cyclic scanning at the communication terminal 60a, it is a communication frame received from the group's repeater 50 (Figure 10: S24, S25: Y → S26). As explained in Embodiment 1, depending on whether or not CCR is detected, the device will either change the communication channel of its own device (Figure 10: S26: Y → S27, S28) or switch to the normal call signal reception and playback mode (Figure 10: S26: N → S35~S38). However, if GID:“01” is not detected in the data payload of the communication frame, it is possible that interference is occurring, in which case the handling described in Embodiment 2 will apply (Figure 10: S25: N → A → Figure 15: S41~S50).

[0075] If the GID: "01" is not detected in the data payload of the communication frame demodulated by the receiving demodulation unit RX11 in the communication terminal 60a, the system control unit 28 starts timing using the built-in interval timer (Figure 15: S41) and checks whether the reception of the radio wave continues for a predetermined time while maintaining the electric field strength (S42, S43). Then, if reception of the radio wave is interrupted before the predetermined time set in the interval timer has elapsed, the timer is reset and the system returns to standby mode (S42:N→B→Figure 10:S21). If a timeout occurs, the timer is reset and the system proceeds to the procedure for changing the channel used by the wireless relay network (S43:Y→S44~S50).

[0076] In other words, the receiving demodulation unit 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 single cycle scan of the L-band group in Figure 3 immediately before the timeout, and changes the currently set channel (CH1-H) of the modulation transmission unit TX11 to the channel corresponding to the selected free pair channel (S44, S45).

[0077] This is the same operating procedure as in the case of the repeater 50 (Figure 9: S12, S13). If the system control unit 28 has created a scan information table in its internal memory in which OFF empty pair channels and ON non-empty pair channels are detected, as shown in the right column of Figure 3, based on the demodulated signal in one cycle scan immediately before the timeout by the receiver demodulator RX11, then the channel number of the currently set pair channel for the receiver demodulator RX11 and the modulation transmitter TX11 is 6 (=CH1). If there is interference on that pair channel, the empty pair channel with the greatest frequency separation from the non-empty pair channel in the scan information table corresponds to channel number 32 (=CH2). Therefore, that empty pair channel (CH2-L and CH2-H) will be changed and set for the receiver demodulator RX11 and the modulation transmitter TX11. The method for determining the "empty pair channel with the greatest frequency separation from the non-empty pair channel" is the same as the algorithm described in the repeater 50 case in Embodiment 1 above, and will be omitted here.

[0078] Figure 14 shows the state in which the receiver / demodulator RX11 and modulation / transmission TX11 of communication terminal 60a have been changed to an available pair channel (CH2-L and CH2-H). Although communication terminal 60a is no longer affected by interference from communication terminal 80 because it has moved to the pair channel with channel number CH2, repeater 50 and communication terminals 60b and 60c are still set to the previous wireless relay network pair channel (channel number: CH1), and their set pair channels will be changed to the aforementioned available pair channel (channel number: CH2).

[0079] Therefore, as shown in the figure, the communication terminal 60a performs carrier sensing on channel CH2-L using the receiver demodulator RX11. If it confirms that the terminal is idle, it immediately turns on the modulation transmitter TX11 and transmits GID:"01" and CCR repeatedly for 1 second. After that, it resumes the cyclic scanning of the receiver demodulator RX11, which had been stopped, and returns to the standby state (Figure 15: S46, S47: Y → S49, S50 → B → Figure 10: S21). However, if the pair channel (channel number: CH2) becomes used by another group or other entity between the timeout of the receiver demodulation unit RX11 and the time of carrier sensing, and the carrier sensing result becomes busy, the next largest pair channel with the frequency separation from the available pair channel is selected and carrier sensing is performed. Subsequently, even if the carrier sensing result becomes busy, carrier sensing is performed again by selecting a pair channel in descending order of frequency separation (S47:N→S48→S45~S47). However, as with the repeater 50 in Embodiment 1, the system is usually idle under the settings of the first pair channel, and it is rare to select the second or third channel or later.

[0080] 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 received only during the cyclic scanning process of the receiver / demodulator RX02 of the repeater 50, which is in standby mode. The receiver / demodulator RX11 on the communication terminals 60b and 60c is controlled to cyclically scan the L-band group shown in Figure 3 and therefore cannot receive them.

[0081] Figure 16 shows the reception / transmission operation related to CCR relay at the repeater 50 in that case. First, in the repeater 50, the receiver / demodulator RX02 constantly scans the H-band group shown in Figure 3. If it receives a radio wave with a predetermined electric field strength or higher during this process, the system control unit 16 temporarily stops scanning on that receiving channel and checks whether GID: "01" and CCR are detected in the data payload of the demodulated communication frame (S61-S64).

[0082] If GID:"01" and CCR are detected, the system control unit 16 will execute the following operation steps (1) to (4) as interrupt processing (S64:Y → S65 to S71). (1) The receiver demodulator RX01 and the modulated transmitter TX01 are set to a pair channel where the channel of the receiver demodulator RX02 in which CCR was detected is the H-band group channel (S66). (2) Switch the signal switching unit 13 to the CCR side (S67). (3) Carrier sensing is performed by the receiver demodulation unit RX01 (S68). (4) If the carrier sense result is idle, the modulation transmitter TX01 transmits GID:"01" and CCR repeatedly on the channel for 1 second (S69:Y→S70). Furthermore, when the interrupt processing is completed, and when GID: "01" and CCR are not detected in step S64, the cyclic operation of the receive demodulation unit RX02 is restarted and the system returns to its original state (S71 / S64 → S72 → S61).

[0083] Therefore, when the repeater 50 receives GID: "01" and CCR on channel CH2-H from the communication terminal 60a, which has received the interfering radio waves, the repeater 50 changes the pair of channels used for relaying, i.e., the channels set by the receive-demodulator RX01 and the modulation-transmitting unit TX01, from (CH1-H, CH1-L) to (CH2-H, CH2-L), as shown in Figure 17, and transmits GID: "01" and CCR to the communication terminals 60a, 60b, and 60c on the transmission channel (CH2-L).

[0084] On the other hand, in communication terminal 60a, the communication pair channel is changed to (CH2-L, CH2-H) when interference signals are received, but the communication pair channels of communication terminals 60b and 60c remain as (CH1-L, CH1-H). However, in standby mode, the receiving demodulation unit RX11 of the communication terminals 60a, 60b, and 60c is in a state of cyclically scanning the channels on the L-band side as shown in Figure 3.

[0085] Therefore, looking at the relationship between the repeater 50 and the communication terminals 60a, 60b, and 60c in the state of the wireless relay network, in Figure 8 of Embodiment 1, the channel of the modulation transmitter TX11 of the communication terminal 60a is CH1-H because the transmission and reception channel of the communication terminal 60a has not been changed. Aside from that, Figure 8 of Embodiment 1 and Figure 17 of this Embodiment 2 are common, and the operating procedure for the communication terminals 60b and 60c is the same as steps S21 to S28 in Figure 10 of Embodiment 1.

[0086] In other words, the setting channels of the receiving demodulation unit RX11 and the modulation transmission unit TX11 of the communication terminals 60b and 60c are changed to pair channels (CH2-L, CH2-H) where the scanning stop channel of the receiving demodulation unit RX11 where CCR is detected is set to the channel on the L band group side, and the receiving demodulation unit RX11 then switches to cyclic scanning operation (S27, S28). Furthermore, while the same change configuration procedure may be performed for the communication terminal 60a, since the transmit and receive channels have already been changed to paired channels (CH2-L, CH2-H), it may be configured to ignore the reception of GID: "01" and CCR from the repeater 50.

[0087] Furthermore, if the carrier sense result in the interrupt processing shown in Figure 16 becomes busy (steps S68, S69:N), the operation procedure of steps S12~S18→S1 in Figure 9 may be executed to cause the repeater 50 to set an available pair channel using its own scanning information table (radio wave reception flag in the right column of Figure 3).

[0088] As a result, as shown in Figure 18, the pair channel used in the relay communication network consisting of the repeater 50 and each communication terminal 60a, 60b, and 60c is changed to channel number CH2 and enters a standby state. Furthermore, as shown in Figure 19, even if there are interfering radio waves to the communication terminal 60a, voice communication can be performed between communication terminals 60a, 60b, and 60c via the repeater 50 using the paired channel of channel number CH2 without any impact, just as in the case of Figure 12 of Embodiment 1 described above. [Industrial applicability]

[0089] The present invention can be applied to a half-duplex wireless relay network system using paired channels, which is usable in radio equipment for specified low-power radio stations / wireless telephones, radio equipment for land mobile service radio stations (for work communication) with antenna power of 1mW or less, and radio equipment for digital simple radio stations. [Explanation of symbols]

[0090] 11...Receiving antenna, 12...Amplifier, RX01, RX02...Receiving demodulation unit, 13...Signal switching unit, TX01...Modulation transmission unit, 14...Amplifier, 15...Transmitting antenna, 16...System control unit, 17...Operation unit, 18...Various indicator lamps, 20...Transmitting and receiving antenna, 21...Antenna switching unit, 22...Amplifier, RX11...Receiving demodulation unit, 23...Amplifier, 24...Speaker (or earphone), 25...Microphone, 26...Amplifier, TX11...Modulation transmission unit, 27...Amplifier, 28...System control unit, 29...Operation unit, 30...Display unit, 50...Wireless repeater, 60a, 60b, 60c...Wireless communication terminal, 70, 80...Wireless communication terminal (source of jamming signals), 100...Wireless repeater, 201, 202...Wireless communication terminal, 301...Wireless communication terminal (source of jamming signals).

Claims

1. A wireless relay system comprising a wireless repeater and a group of wireless communication terminals constituting a single group, wherein a single pair channel is selected from a group of two channels (hereinafter referred to as "pair channels") that are designated as paired waves usable for uplink and downlink communication between the wireless repeater and each wireless communication terminal in accordance with the standards established based on the Radio Law Enforcement Regulations and the Radio Equipment Regulations, and the system performs group communication between the wireless communication terminals using a half-duplex method, The aforementioned wireless repeater is The system comprises a receiver / demodulator A, a receiver / demodulator B, a modulation / transmission unit C, and a control unit that controls them. The receiver / demodulator A and the modulation / transmission unit C are each assigned one pair of channels, while the receiver / demodulator B scans through a group of channels available as receiving channels for the receiver / demodulator A and searches for available channels. In standby / receive mode, the receiver / demodulator A and the receiver / demodulator B are in the ON state, and the modulation / transmission unit C is in the OFF state. When group identification information relating to the group is detected and confirmed from the demodulated signal of the receiver / demodulator A, the system switches to relay mode. In relay 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. In addition, in the standby / receive mode, if the reception demodulation unit A receives radio waves with a certain electric field strength or higher for a predetermined time or longer in which it cannot detect and confirm the group identification information from its demodulated signal, the set pair channel of the reception demodulation unit A and the modulation transmission unit C is changed to a pair channel related to an available channel searched 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 aforementioned wireless communication terminals is: The system comprises a receiver / demodulator D, a modulation / transmission unit E, and a control unit that controls them. The receiver / demodulator D and the modulation / transmission unit E are set to the same pair channels as those set in the receiver / demodulator A and modulation / transmission unit C on the wireless repeater side, but in reverse order for transmission and reception. In standby mode, the receiver / demodulator D scans through a group of channels available as reception channels. In reception mode, the receiver / demodulator D is turned ON and the modulation / transmission unit E is turned OFF, and the demodulated signal output by the receiver / demodulator D is reproduced as audio. In transmission mode, the receiver / demodulator D is turned OFF and the modulation / transmission unit E is turned ON, and the carrier wave of the transmission channel of the modulation / transmission unit E is modulated with the input audio signal and transmitted. In addition, in standby mode, if the receiver / demodulator D receives the group identification information and channel change request information transmitted by the wireless repeater side during its scanning process, the receiver / demodulator D and the modulation / transmission unit E are set to the reception channel and its pair channel, respectively. A wireless relay system characterized by the following features.

2. The wireless relay system according to claim 1, wherein in the wireless relay, when the receiving demodulation unit A receives radio waves with a certain electric field strength or greater for a predetermined period of time or longer in which the group identification information cannot be confirmed from the demodulated signal, and when multiple empty pair channels are detected in the one-cycle scanning process by the receiving demodulation unit B immediately before the detection of reception for a predetermined period of time or longer, the receiving demodulation unit A and the modulation transmission unit C are set to change to the empty pair channel with the largest frequency separation from the non-empty pair channels, and the modulation transmission unit C transmits the group identification information and channel change request information.

3. The wireless relay system according to claim 2, wherein, in the wireless relay, when carrier sensing is performed using the receiving demodulation unit A prior to the transmission operation of the modulation transmission unit C, the available pair channels are selected in order of decreasing frequency separation from the non-available pair channels and carrier sensing is performed.

4. A wireless relay system comprising a wireless repeater and a group of wireless communication terminals constituting a single group, wherein a single pair channel is selected from a group of two channels (hereinafter referred to as "pair channels") that are designated as paired waves usable for uplink and downlink communication between the wireless repeater and each wireless communication terminal in accordance with the standards established based on the Radio Law Enforcement Regulations and the Radio Equipment Regulations, and the system performs group communication between the wireless communication terminals using a half-duplex method, The aforementioned wireless repeater is The system comprises a receiver / demodulator A, a receiver / demodulator B, a modulation / transmission unit C, and a control unit that controls them. The receiver / demodulator A and the modulation / transmission unit C are each assigned one pair of channels, while the receiver / demodulator B cycles through a group of channels available as receiving channels for the receiver / demodulator A. In standby / receive mode, the receiver / demodulator A and the receiver / demodulator B are ON, and the modulation / transmission unit C is OFF. When group identification information relating to the group is detected and confirmed from the demodulated signal of the receiver / demodulator A, the system switches to relay mode. In relay mode, the modulation / transmission unit C is set to ON. With unit C in the ON state, the carrier wave of the transmission channel is modulated and transmitted using the demodulated signal output by the receiver / demodulator unit A. In addition, in the standby / receive mode, if the receiver / demodulator unit B receives the group identification information and channel change request information transmitted by any of the wireless communication terminals during its cyclic scanning process, it sets the receiving channel and the channel that is its paired channel to the receiver / demodulator unit A and the modulation / transmission unit C, respectively, and transmits the group identification information and the channel change request information from the modulation / transmission unit C. Each of the aforementioned wireless communication terminals is: The system comprises a receiver / demodulator D, a modulation / transmitting unit E, and a control unit that controls them. The receiver / demodulator D and the modulation / transmitting unit E are configured with the same pair channels set in the receiver / demodulator A and modulation / transmitting unit C on the wireless repeater side, but in reverse order for transmission and reception. In standby mode, the receiver / demodulator D scans through a group of channels available as reception channels and searches for an empty channel. In reception mode, the receiver / demodulator D is turned ON and the modulation / transmitting unit E is turned OFF, and the demodulated signal output by the receiver / demodulator D is reproduced as audio. In transmission mode, the receiver / demodulator D is turned OFF and the modulation / transmitting unit E is turned ON, and the carrier wave of the transmission channel of the modulation / transmitting unit E is modulated with the input audio signal and transmitted. In standby mode, if the receiver / demodulator D receives radio waves with a certain electric field strength or higher for a predetermined period of time or longer in which it cannot detect and confirm the group identification information from the demodulated signal, the receiver / demodulator D changes the set pair channel of the receiver / demodulator D and the modulation / transmitting unit E to a pair channel related to an available channel searched by the receiver / demodulator D, and turns on the modulation / transmitting unit E to transmit the group identification information and the channel change request information. On the other hand, 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, it sets the receiving channel and the channel that is its pair channel to the receiver / demodulator D and the modulation / transmitting unit E, respectively. A wireless relay system characterized by the following features.

5. The wireless relay system according to claim 4, wherein in the wireless communication terminal, when the receiving demodulation unit D receives radio waves with a certain electric field strength or greater for a predetermined period of time or longer in which the group identification information cannot be confirmed from the demodulated signal, and when multiple empty pair channels are detected in the one-cycle scanning process by the receiving demodulation unit D immediately before the detection of reception for a predetermined period of time or longer, the receiving demodulation unit D and the modulation transmission unit E are set to change the empty pair channel with the largest frequency separation from the non-empty pair channels, and the modulation transmission unit E transmits the group identification information and channel change request information.

6. The wireless relay system according to claim 5, wherein, in the wireless communication terminal, when carrier sensing is performed using the receiving demodulation unit D prior to the transmission operation of the modulation transmission unit E, the available pair channels are selected in order of decreasing frequency separation from the non-available pair channels and carrier sensing is performed.

Images