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JP-2026074735-A - Wireless relay system

JP2026074735AJP 2026074735 AJP2026074735 AJP 2026074735AJP-2026074735-A

Abstract

[Problem] In a wireless relay system that performs group communication using a half-duplex 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 is equipped with 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. [Selection Diagram] Figure 8

Inventors

  • 村石 正俊

Assignees

  • 八重洲無線株式会社

Dates

Publication Date
20260507
Application Date
20241021

Claims (6)

  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 repeater, when the receiving demodulation unit A receives radio waves with a certain electric field strength or higher for a predetermined period of time or longer, and when multiple empty pair channels are detected in the one-cycle scan process by the receiving demodulation unit B immediately before the detection of the reception for the predetermined period or longer, the receiving demodulation unit A and the modulation transmission unit C are set 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 accordingly.
  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. A wireless relay system characterized in that, in standby mode, if 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 it cannot detect and confirm the group identification information from its 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, while 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 in a pair channel relationship with it to the receiving demodulation unit D and the modulation transmission unit E, respectively.
  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 higher for a predetermined period of time or longer, and when multiple empty pair channels are detected in the one-cycle scan process by the receiving demodulation unit D immediately before the detection of the reception for a predetermined period 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 system selects available pair channels in order of decreasing frequency separation from non-available pair channels and performs carrier sensing.

Description

This invention relates to a wireless relay system comprising a wireless repeater and a plurality of wireless communication terminals that communicate with each other using a half-duplex method through the repeater, and which automatically changes the currently used pair channel to an available pair channel when interference is detected on the wireless repeater or wireless communication terminals. Traditionally, in group communications using commercial wireless communication equipment, which are low-power radio stations, wireless repeaters (master stations) are often installed to expand the communication area, enable communication with multi-story buildings or separate buildings, and ensure communication and improve call quality in areas where radio waves are difficult to reach due to obstacles, etc. A group communication network is formed using wireless communication terminals that pass through these wireless repeaters. Furthermore, in the case of professional radio communication equipment that is a land mobile radio station (for work communication) with an antenna power of 1 mW or less, communication between slave stations via a master station is the basic method, resulting in a group communication network similar to that described above. Furthermore, in these networks, communication between each wireless communication terminal is conducted using a half-duplex system via wireless repeaters. Paired channels (mutually paired waves) are used for the uplink and downlink waves involved in this communication. The available paired channels are determined according to the type of radio wave and communication method in the standards established based on 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 are classified as low-power radio stations, the 27 pairs of paired channels shown in Figure 3 are available for use. Here, we 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 Figure 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. 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. By the way, if another communication network is started in a location adjacent 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. 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 may occur again, and stable communication cannot be expected as long as the paire