Wireless communication equipment and wireless communication network systems

Abstract

In simplex group communication using wireless communication terminals, the aim is to maintain communication on the least frequently used channel (CH) in the event of interference. [Solution] Each terminal is equipped with a channel selection table that defines combination channels by dividing the channel list into groups of two channels from the top in ascending order of frequency of use. The current channel (one of the combination channels) is set in the receiver demodulator RX1, while the receiver demodulator RX2 alternately scans the sub-channel (the other of the combination channel) and the common channel (e.g., frequency control channel). If the current channel is interfered with but the sub-channel is not, each terminal will swap the two set channels and send a channel change request to set other terminals to the same channel setting state. If both the current channel and the sub-channel are interfered with, the next-highest combination channel will be applied and a combination channel change request will be sent on the common channel to set other terminals to the same channel setting state.

Description

Technical Field

[0001] The present invention relates to a wireless communication device and a wireless communication network system for enabling all terminals in a group to quickly switch to an idle channel and maintain stable communication when interference occurs in a channel being used in single-hop group wireless communication.

Background Art

[0002] Wireless communication devices conforming to a specific low-power standard are used for voice communication at short distances using the 400 MHz band and are also license-exempt stations. Therefore, outdoors, they are used for business communication among workers at various construction sites such as construction sites, and indoors, they are used in relatively large restaurants and home centers with large spaces.

[0003] The wireless communication device conforming to the specific low-power standard is based on the standards established in Non-Patent Document 1 below and defines available channels as follows. In the first volume of the same document, for communication by a single-hop method with an antenna power of 10 mW or less in a plurality of radio wave types such as F3E, 422.0500 to 422.1750 MHz is divided at intervals of 12.5 kHz, and 11 channels with channel numbers CH-20 to 30 (Table 3-3) and 422.2000 to 422.3000 MHz are divided at intervals of 12.5 kHz, and 9 channels with channel numbers CH-41 to CH-49 (Table 3-5) are allocated, and CH-31 (422.1875 MHz) can be used as a frequency control channel under the restriction that the transmission time is within 0.5 seconds. Furthermore, Part 2 of the same document pertains to the quad-level FSK digital system among the radio stations of the same standard. For simplex communication using F1D or F1E emission types with antenna power of 10mW or less, 20 channels (Table 3-2) are allocated, consisting of channel numbers CH-1 to 21 and CH-22 to 38 (except CH-15, which is the calling channel), by dividing the 422.053125~422.178125MHz and 422.196875~422.296875MHz frequencies at 6.25kHz intervals. In addition, channel numbers CH-C1 (422.184375MHz) and CH-C2 (422.190625MHz) are available as frequency control channels with a transmission time limit of 0.5 seconds or less.

[0004] The above pertains to wireless communication devices conforming to the specified low-power standard. However, digital simple wireless devices utilize a digital communication method, resulting in better sound quality, higher security, and the ability to output antenna power up to 5W. For these reasons, they are widely used for communication at event venues and leisure facilities, as well as for security operations.

[0005] The digital simple radio station is based on the standards established in Non-Patent Document 2 below. The standard is divided into three modulation schemes (π / 4 shift four-phase phase modulation, real zero single-sideband modulation, and four-level frequency shift modulation), each employing a different radio wave type. However, for licensed stations, 75 channels are allocated, consisting of channel numbers CH-1 to CH-65 and CH-66 to CH-75, which are divided at 6.25kHz intervals between 467.00000~467.40000MHz and 465.096875~465.153125MHz, and 154.44375~154.61250MHz, also divided at 6.25kHz intervals. 28 channels are allocated, numbered CH-1 to CH-28. Registered stations are allocated 82 channels consisting of channel numbers CH-1 to CH-50 and CH-51 to CH-82, which divide 351.20000 to 351.50625 MHz and 351.51250 to 351.10000 MHz at 6.25 kHz intervals, and 15 channels consisting of channel numbers CH-S1 to CH-S15, which divide 351.16875 to 351.16250 MHz at 6.25 kHz intervals (including stations with 1W or less and those operating in the air).

[0006] When the wireless communication devices of the aforementioned standards are used for business communication between employees at construction sites, home improvement stores, etc., a simplex group communication network is configured, and one channel is selected as the group channel from the available channel group to perform communication. However, even if there are many available channels, if the frequencies used by other communication networks operating nearby are the same or close together, interference often occurs continuously, making it difficult to hear the voice of the conversation.

[0007] Conventionally, measures to avoid this interference have been proposed, such as those described in Patent Documents 1-3 below. The proposal in Patent Document 1 below involves repeatedly scanning available channels to determine the past frequency of available channels for each channel in advance, and then, when interference occurs on the currently used channel, selecting the channel with the highest frequency of available channels as the destination channel.

[0008] The proposal in Patent Document 2 below describes a method for changing the channel used for network or one-to-one communication when interference occurs in network or one-to-one wireless communication. This is achieved by one of the wireless communication devices, once the level of the unwanted radio waves causing the interference has decreased to a level where communication is possible, transmitting a channel switching signal to the other wireless communication device, which consists of available channel information obtained by performing a prior available channel search and a switching signal.

[0009] The proposal in Patent Document 3 below describes a wireless communication device that performs simplex wireless communication in a group network with other wireless communication devices of the same configuration, and includes a second receive-demodulate unit along with a transmit / receive unit consisting of a modulation transmit unit and a first receive-demodulate unit. In receive / standby mode, the second receive-demodulate unit repeatedly scans all channels available in the group network and determines whether each channel is an available channel, thereby updating and recording channel selection priority data for available channels. Furthermore, if the group identification code and channel change command are included in the received signal of an interfering channel during the scanning process of the second receive-demodulate unit, the modulation transmit unit and the first receive-demodulate unit are set to that interfering channel. On the other hand, when transitioning to transmit mode, if there is interference in carrier sense, carrier sense is performed sequentially from the highest-ranking channel in the channel selection priority data, the first available channel detected is set as the transmit / receive channel, the group identification code and channel change command are transmitted, and then the device transitions to transmitting the call signal. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 6-112859 [Patent Document 2] Japanese Patent Application Publication No. 10-75194 [Patent Document 3] Patent No. 7431371 [Non-patent literature]

[0011] [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 Digital Simple Radio Stations," ARIB STD-T98 2.0, revised October 4, 2023. [Overview of the project] [Problems that the invention aims to solve]

[0012] The proposals in the above-mentioned Patent Documents 1-3 all relate to the transition to other channels when interference occurs on the currently used channels in a wireless communication network, but the following issues remain. Patent Document 1 proposes channel selection criteria in the event of interference on the channel being used, but it does not describe the specific procedure for changing the channel used for the entire network when interference occurs during network operation. Furthermore, the proposal in Patent Document 2 is a technology that supplements the above-mentioned automatic channel selection function, and its condition is that the level of unwanted radio waves on the currently used channel experiencing interference must decrease to a level where communication is possible. However, once interference occurs, this condition is not always met, and if the interference continues for a long time, the system will have no choice but to remain on standby, so there is no guarantee that it will always be possible to switch to an available channel.

[0013] The proposal in Patent Document 3 is by the applicant of this application and enables the selection of a rational available channel and the smooth switching of network channels when interference occurs on the currently used channel. However, each time interference occurs, the system will sequentially shift to channels with a lower probability of availability (channels with higher usage frequency) based on the channel selection priority data. However, even if a channel with a higher selection priority (a channel with lower usage frequency) experiences temporary interference, it may recover to a stable, available state. In such cases, it is desirable to use the highest-ranking channel possible for communication, but this system has the disadvantage of sequentially shifting to lower-ranking channels.

[0014] Therefore, the present invention aims to provide a wireless communication device and wireless communication network system that enables the continuation of good communication while quickly and stably avoiding interference when interference occurs on the channel used by the device due to jamming radio waves, etc., by having each wireless communication terminal have a channel selection ranking table based on the ascending order of channel usage frequency in advance, and using combinations of 2 channels from the top of the table as channel setting units for the transmitting and receiving unit. [Means for solving the problem]

[0015] The first invention is a wireless communication device comprising a transmitting / receiving unit consisting of a modulation transmitting unit and a first receiving / demodulating unit, a second receiving / demodulating unit, a control unit for controlling their operation, and a data storage unit, which forms a group network with other wireless communication devices of the same configuration and performs simplex group communication, wherein the data storage unit stores all or a predetermined number of channel information from the top of the channel information, which is ranked in ascending order based on the frequency of use over a certain period of time in the past, for all or some of the channels that can be used for communication in accordance with the radio station standard, as a channel selection table, and is defined as comprising N sets (N is an integer of 2 or more) of combination channels divided into groups of two channels from the top, and the N sets of combination channels are used sequentially from the highest combination, and in the receive / standby mode, one of the combination channels is set as the current transmitting / receiving channel (hereinafter referred to as the "current channel") for the group communication in the first receiving / demodulating unit and its demodulated signal is reproduced as audio, while the second receiving / demodulating unit is set as the other channel (hereinafter referred to as the "sub-channel") of the combination channel The system is controlled to alternately scan the current channel (hereinafter referred to as the "common channel") and the frequency control channel defined in the radio station standard (hereinafter referred to as the "common channel") so as to obtain a received demodulated signal on each of the scanning channels, and when interference of the current channel is detected in the first receive demodulation unit and interference of the subchannel is not detected in the second receive demodulation unit, the setting channels of the current channel and the subchannel are swapped, and the modulation transmission unit transmits a first channel change request signal on the swapped current channel, and when interference of the current channel is detected in the first receive demodulation unit and interference of the subchannel is detected in the second receive demodulation unit, the modulation transmission unit is temporarily switched to the common channel and a second channel change request signal is transmitted, and the current channel and the subchannel are changed to the channels related to the next-order combination channel, respectively, and when the second receive demodulation unit receives the first channel change request signal transmitted by the other radio communication device during the scanning process of the subchannel,The present invention relates to a wireless communication device characterized by performing a third control procedure for swapping and changing the setting channels of the current channel and the subchannel, and a fourth control procedure for changing the current channel and the subchannel to the channels related to the next-ranked combination channel in the channel selection table, when the second receiver / demodulator receives the second channel change request signal transmitted by the other wireless communication device during the scanning process of the shared channel by the second receiver / demodulator.

[0016] The wireless communication device of this first invention includes, in addition to a normal transmitting and receiving unit consisting of a modulation transmitting unit and a first receiving and demodulating unit, a second receiving and demodulating unit, similar to the one proposed in Patent Document 3, and also includes a data storage unit that stores a channel selection table in advance. This channel selection table ranks all or some of the usable channels (see the [Background Art] section) specified in the above Non-Patent Documents 1 and 2, etc., in ascending order based on the frequency of use of each channel over a certain period of time in the past. Furthermore, it consists of all or a predetermined number of the top ranked channel information. In that case, the appropriateness of measuring channel usage frequency largely depends on the network environment of the group communication, and the length of the "past certain period of time" cannot be set uniformly and is often determined by experience. For example, in urban areas where interference is relatively likely to occur, several hours may be expected, while in suburban areas with few radio wave sources, several minutes is often sufficient.

[0017] Each channel in the channel selection table is defined as being composed of N sets of combined channels (where N is an integer greater than or equal to 2), each consisting of two channels from top to bottom. These N sets of combined channels are then used sequentially, starting with the highest-ranking combination.

[0018] In the wireless communication device of this invention, the modulation transmission unit and the first reception demodulation unit are set to the current channel, which is the current transmission / reception channel, while the second reception demodulation unit alternately scans the subchannel and the common channel in reception / standby mode. Here, the combined channels of the channel selection table are set for the current channel and the sub-channel respectively, and the channel for frequency control is set for the common channel.

[0019] On the premise above, when there is no interference in the current channel of the first reception demodulation unit, group communication by the single-signal method using the set channel can be carried out without problems. Therefore, in the reception / waiting mode, the demodulated signal of the current channel output from the first reception demodulation unit is used for voice playback, and in the transmission mode, the modulation transmission unit is set to the current channel and a signal obtained by modulating a carrier signal with a signal such as input voice is transmitted.

[0020] On the other hand, when interference occurs in the current channel of the first reception demodulation unit, the corresponding operations differ depending on whether there is interference in the sub-channel during the alternate scanning process of the second reception demodulation unit. Here, "interference" may occur when receiving radio waves of other communications using a channel identical or close to the current channel, or when receiving artificial noise radio waves from other noise sources such as an inverter. However, it is determined whether the signal is an interference signal based on whether a group identification signal is detected, and for determining whether the interference level is such that normal transmission and reception cannot be performed, the signal-to-noise ratio, bit error rate (BER), and other interference degrees in the frequency spectrum analysis results can be used.

[0021] When the sub-channel is not in an interference state, the first control procedure is executed. That is, the channels set for the current channel and the sub-channel are mutually swapped, the channel that was the sub-channel until then is used for transmission and reception as the current channel, and a first channel change request signal is transmitted from the modulation transmission unit using the current channel after the swap.

[0022] On the other hand, when the sub-channel is also in an interference state, the second control procedure is executed. In other words, the only communication channel available to other wireless communication devices in the group network is the common channel. The modulation transmission unit temporarily switches to the common channel and sends a second channel change request signal. At the same time, it abandons the use of the combination channels that were previously set as the current channel and subchannel, and changes them to the channels corresponding to the next-level combination channel. In this case, the common channel, the frequency control channel, tends to be used relatively frequently because it is used for a variety of purposes in communication. However, because its transmission time is limited to within 0.5 seconds, idle (non-interference) periods occur frequently, making it suitable for the purpose of transmitting only the second channel change request signal in this invention.

[0023] The first and second control procedures described above are procedures in which the device detects interference on the current channel and actively changes the communication channel of the group network. Conversely, if the device receives the first or second channel change request signal transmitted by another radio communication device, it executes the following third and fourth control procedures, respectively.

[0024] In other wireless communication devices, when interference is detected on the current channel but not on the subchannel, the settings for both channels are swapped as described above, and then the first channel change request signal is transmitted on the changed current channel. This transmission channel corresponds to the subchannel in the device itself. Therefore, in the third control procedure, when the receiver demodulator receives the first channel change request signal during the subchannel scanning process, it swaps and changes the setting channels of both channels to match the current channel and subchannel setting channels of another radio communication device.

[0025] Furthermore, in other wireless communication devices, when there is interference between the current channel and subchannel, a second channel change request signal is transmitted on the common channel as described above to change the current channel and subchannel to the channels related to the next-highest combination channel. However, in this device, the second channel change request signal is received during the scanning process of the common channel. Therefore, in the fourth control procedure, upon receiving the second channel change request signal, the channels related to the next-level combination channel are changed to match the current channel and subchannel settings of other radio transceivers.

[0026] The second invention is a wireless communication device comprising a transmitting / receiving unit consisting of a modulation transmitting unit and a first receiving / demodulating unit, a second receiving / demodulating unit and a control unit for controlling their operation, and a data storage unit, which forms a group network with other wireless communication devices of the same configuration and performs simplex group communication, wherein the data storage unit stores all or a predetermined number of channel information from the top, ranked in ascending order based on the frequency of use over a certain period of time in the past, for all or some of the channels that can be used for communication in accordance with the radio station standard, as a channel selection table, and for the top (2*N+1) channels (N is an integer of 2 or more) in the channel selection table, one channel is defined as a common channel, and the remaining channels are defined as being composed of N sets of combination channels divided into groups of two channels from the top, and the N sets of combination channels are used sequentially from the highest combination, and in the receive / standby mode, the first receiving / demodulating unit is set to the current transmitting / receiving channel for the group communication (hereinafter referred to as the "current channel") One channel of the combination channel is set and its demodulated signal is reproduced as audio, while the second receiver / demodulator is controlled to alternately scan the other channel of the combination channel (hereinafter referred to as "subchannel") and the common channel to obtain a received / demodulated signal for each scanned channel. When interference of the current channel is detected by the first receiver / demodulator, and no interference of the subchannel is detected by the second receiver / demodulator, the set channels of the current channel and the subchannel are swapped, and the modulation transmission unit transmits a first channel change request signal on the swapped current channel. When interference of the current channel is detected by the first receiver / demodulator, and no interference of the subchannel is detected by the second receiver / demodulator, the modulation transmission unit is temporarily switched to the common channel and a second channel change request signal is transmitted, and the current channel and the subchannel are changed to the channels of the next combination channel, respectively.The present invention relates to a wireless communication device characterized by the following: when the second receiver / demodulator receives the first channel change request signal transmitted by the other wireless communication device during the scanning process of the subchannel, it performs a third control procedure to swap and change the current channel and the subchannel's respective setting channels; and when the second receiver / demodulator receives the second channel change request signal transmitted by the other wireless communication device during the scanning process of the shared channel, it performs a fourth control procedure to change the current channel and the subchannel to the channels related to the next-ranked combination channel in the channel selection table.

[0027] The only difference between this second invention and the first invention is that, unlike the first invention, it does not apply a frequency control channel as a common channel. Instead, when creating the channel selection table, it selects the top (2*N+1) candidates, chooses one channel from among them to be used as the common channel, and uses the other (2*N) as the channel selection table. The rest of the configuration is the same. As mentioned earlier, frequency control channels tend to be used relatively frequently, and there is a high possibility of the carrier sense becoming busy when transmitting the second channel change request signal. However, because idle (non-interference) periods occur frequently, even if the channel becomes busy, signal transmission becomes possible within a few seconds. In contrast, this second invention uses a common channel selected from the channels with the highest usage frequency in ascending order. This results in the opposite trend to that of frequency-controlled channels, where a stable idle state is maintained unless the channel is busy at the time of use. Therefore, it may actually be effective in radio wave environments where frequency control channels are frequently used, such as in urban areas. Furthermore, in the case of the digital simple radio station described in Non-Patent Document 2 above, the number of channels it can use is far greater than that of a specified low-power radio station, and there is no equivalent to a frequency control channel, therefore this second invention applies.

[0028] In the first or second invention described above, in the alternating scanning of the subchannel and the common channel by the second receiver demodulator in the receive / standby mode, it is desirable to set the scanning time of the subchannel to several tens of ms and to set the scanning period of both channels within the range of 200 ms to 600 ms. Regarding the scanning time for subchannels, it is necessary to ensure sufficient time to check whether or not there is interference on that channel, and this check should be performed at the shortest possible interval. On the other hand, the scanning time for common channels should naturally be longer, as this is the time period during which other radio transceivers can receive a second channel change request signal. In the wireless communication devices of each of the above inventions, the above range can be recommended as a preferred condition for alternating scanning that satisfies such requirements in an eclectic manner.

[0029] In the first or second invention described above, when setting the highest-ranking combination channel in the channel selection table to the current channel and the subchannel at the start of the group communication, and when changing the current channel and the subchannel to the next-ranking combination channel in the channel selection table upon receiving the second channel change request signal, it is desirable to set / change the higher-ranking channel to the current channel side and the lower-ranking channel to the subchannel side. When starting group communication or when receiving a second channel change request signal to set the combined channels as the current channel and subchannel, setting the higher-ranking channel, which has a lower usage frequency rating in the channel selection table, as the current channel will result in more probabilistically stable communication.

[0030] The third invention is a wireless communication network system in which each terminal of a group communication network is a wireless communication device according to the first or second invention, and when interference of the current channel is detected by the first receiver / demodulator, and no interference of the subchannel is detected by the second receiver / demodulator, the current channel and the subchannel's set channels are swapped, and the modulation transmission unit transmits the first channel change request signal on the swapped current channel, and when interference of the subchannel is detected by the second receiver / demodulator, the modulation transmission unit is temporarily switched to the common channel and the second channel change request signal is transmitted. The present invention relates to a wireless communication network system characterized in that, while the current channel and the subchannel are changed to the channels related to the next-ranking combination channel, if any of the other component terminals receive the first channel change request signal during the subchannel scanning process by the second receiver / demodulator, the current channel and the subchannel are swapped and changed to the respective set channels of the current channel and the subchannel. If the second receiver / demodulator receives the second channel change request signal during the shared channel scanning process by the second receiver / demodulator, the current channel and the subchannel are changed to the channels related to the next-ranking combination channel in the channel selection table. [Effects of the Invention]

[0031] The wireless communication device and wireless communication network system of the present invention, when interference occurs in the channel used (current channel) in the group communication network, does not use a method of sequentially switching to the channel used from the least frequently used channel, but rather checks the interference status in units of combined channels divided into pairs of channels in order of frequency of use, and even if one channel is interfered with, if the other channel is not interfered with, it is possible to alternately switch to the other current channel. Therefore, even if interference occurs temporarily, it is possible to return to the original current channel, and by automatically switching to the channel with the least frequency of use whenever possible, it is possible to achieve more stable group communication while automatically avoiding interference. Furthermore, the wireless communication device of the present invention has a functional configuration in which the first receiver / demodulator is always responsible for receiving and demodulating signals on the current channel, and the second receiver / demodulator obtains information for channel change control when interference occurs on the current channel by alternating scanning of the subchannel and the common channel. As a result, the playback of the audio signal on the current channel is not interrupted except when changing channels, and the interruption time can be kept to an extremely short period. [Brief explanation of the drawing]

[0032] [Figure 1] This is a block diagram of a wireless communication device according to an embodiment of the present invention. [Figure 2] This is a flowchart showing the steps for executing the table creation mode. [Figure 3] This diagram shows the procedure for creating a channel selection table and the definition of combined channels. [Figure 4] This flowchart shows the operation procedures for terminal 101 and terminals 102, 103, and 104 in table sharing mode. [Figure 5] This diagram shows the communication frame format used by the wireless communication device according to this embodiment in group communication. [Figure 6] This is an explanatory diagram relating to the alternating scan control of the receiving channel performed by the receiving demodulation unit RX2 of the wireless communication device according to the embodiment during the receive / standby mode. [Figure 7A] This flowchart shows the procedure for changing the communication channel when interference occurs with group communication between terminals (wireless communication devices). [Figure 7B] This flowchart shows the procedure for changing the communication channel when interference occurs with group communication between terminals (wireless communication devices). [Figure 8] This flowchart shows the operation procedure (interrupt routine) when a terminal (wireless communication device) receives a channel change request signal or a combined channel change request signal in receive / standby mode. [Figure 9] This is a simplified network configuration diagram (current channel: CH-a, where group communication is possible). [Figure 10] This is a simplified network configuration diagram (terminal 101 experiences interference on the current channel: CH-a / subchannel: CH-b is free from interference). [Figure 11] This is a simplified network configuration diagram (terminal 101 swaps and changes the current channel and subchannel settings / terminal 101 sends a channel change request signal). [Figure 12] This is a simplified network configuration diagram (channel: avoiding interference on CH-a / current channel: enabling group communication on CH-b). [Figure 13] This is a simplified network configuration diagram (terminal 101 experiences interference on current channel: CH-b / interference on channel: CH-a disappears / terminal 101 swaps the current channel and subchannel settings / terminal 101 sends a channel change request signal). [Figure 14] This is a simplified network configuration diagram (channel: avoiding interference on CH-b / current channel: enabling group communication on CH-a). [Figure 15] This is a simplified network configuration diagram (showing interference occurring on the current channel: CH-b and subchannel: CH-a). [Figure 16]This is a simplified network configuration diagram (terminal 101 experiences interference on the current channel: CH-b and subchannel: CH-a / terminal 101 sends a combined channel change request signal on the common channel: CH-z). [Figure 17] This is a simplified network configuration diagram (to avoid interference between the current channel: CH-b and subchannel: CH-a / the next-level combined channels CH-c and CH-d are applied to the current channel and subchannel). [Modes for carrying out the invention]

[0033] Hereinafter, embodiments of the wireless communication device and wireless communication network of the present invention will be described in detail with reference to the drawings. First, Figure 1 is a block diagram of a wireless communication device (equivalent to a low-power radio station) according to an embodiment of the present invention, and this wireless communication device becomes terminals 101 to 104 that constitute a group network in the simplified network configuration diagrams from Figures 9 to 17.

[0034] In the receiving system of the wireless communication device shown in Figure 1, the broadband received signal obtained from the antenna 10 is input from the distributor 11 to two receive-demodulation units RX1 and RX2 via the amplifier 12. In receive-standby mode, receive-demodulation unit RX1 demodulates the signal related to the set channel (the current channel, which is the channel for sending and receiving group communication) within the received signal and outputs it to the amplifier 13. The amplified demodulated signal is then played back as sound by the speaker (or earphone) 14. Meanwhile, as will be described later, receive-demodulation unit RX2 alternately scans the subchannel and the common channel at a constant period, and outputs the received-demodulation signals for each channel to the port of the system control unit 15. Meanwhile, in the transmission system, the input audio signal from the microphone 16 is input to the modulation transmission unit TX1 via the amplifier 17. The modulation transmission unit TX1 modulates the carrier of the set channel with the input audio signal and outputs it to the amplifier 18. The modulated signal, power amplified by the amplifier 18, is then transmitted as radio waves from the antenna 10 via the distributor 11.

[0035] The entire wireless communication device is controlled by the system control unit 15, which receives signals from each module such as the modulation transmitter TX1 and the receiver demodulation units RX1 and RX2, as well as input signals from the operation unit 19, and performs operation control of each module, as well as control of the display of information on the liquid crystal display unit 20. Furthermore, in a group network where this wireless communication device is used as terminals 101 to 104, as described later, a table creation mode and a table sharing mode are set to share the channel selection table in the memory 21 of each terminal 101 to 104. In setting the channels for the modulation transmission unit TX1 and the receiver demodulation units RX1 and RX2, the channel selection table is referenced, and the system control unit 15 also performs read / write operations on the channel information to and from the memory 21.

[0036] The procedure for executing the table creation mode is shown in Figure 2. This mode only needs to be executed by any of the wireless communication devices (terminals 101-104) that make up the group network; in this case, terminal 101 will execute it. First, when the operation unit 19 sets the table creation mode on terminal 101, the system control unit 15 scans the 20 channels (CH-20~30, CH-41~49) that are permitted for use in simplex communication according to the standard specifications for low-power radio stations at regular intervals for a set period of time, checks whether there is interference for each channel, and records the frequency of use information (S1, S2).

[0037] Specifically, the frequencies for channels CH-20~30 and CH-41~49 are pre-stored in memory 21, and the system control unit 15 sequentially sets each of these frequencies to the receiver / demodulator RX1 for 0.1 seconds each, scanning all 20 channels in a cycle over 2 to 3 hours with a period of about 2 seconds. Each time, it determines whether or not interference is present for each channel and stores the cumulative number of times interference is present as usage frequency information in memory 21. It is not necessary to perform the above procedure on all channels CH-20~30 and CH41~49; it may be performed on only a portion of them (for example, channels CH-20~30). Furthermore, this mode is equivalent to the preliminary preparation for group communication, and it is not necessarily required to perform a cyclic scan using the receiver / demodulator RX1; the receiver / demodulator RX2 may be used instead.

[0038] Next, based on the usage frequency information stored in memory 21, eight channels (CH-a to CH-h in ascending order of usage frequency) are selected in ascending order of usage frequency, as shown in Figure 3. A channel selection table is then created with these channels as the target channels, and stored in memory 21, thereby automatically deactivating the table creation mode (S3, S4). In this embodiment, only the top 8 channels of the frequency usage information from memory 21 are used, but all channels from which frequency usage information is obtained may also be used.

[0039] As described above, the channel selection table is stored in the memory 21 of terminal 101, but this channel selection table must also be shared by the other terminals 102 to 104 that make up the network. Therefore, each terminal 101 to 104 sets up table sharing mode, sends channel selection table data from terminal 101, and terminals 102 to 104 receive that data and store it in memory 21.

[0040] Figure 4 shows the operation procedure for terminals 101 and 102-104 in table sharing mode. First, when users of terminals 101 to 104 gather and set the shared table mode on each terminal (S11, S12), terminal 101, which has already stored the channel selection table in memory 21, searches for an available channel by sequentially setting channels CH-a to CH-h on the receive demodulation unit RX1 and scanning (S13). In this case, since channels CH-a to CH-h are in ascending order of usage frequency, the channel CH-a, which is almost the highest-ranking channel, or a channel close to it, will be detected as an available channel. Here, we will refer to that available channel as CH-x.

[0041] When the system control unit 15 of terminal 101 detects channel CH-x, it sets it as the transmit / receive channel and displays the channel information on the display unit 23 (S14). Here, as described above, the users of each terminal 101 to 104 are gathered together, so based on the display on terminal 101 or a notification from that user, the users of terminals 102 to 104 set channel CH-x as their own transmit / receive channel from the operation unit 19 (S15, S16).

[0042] Then, when the transmission setting is made on terminal 101, the system control unit 15 transmits the channel selection table data stored in memory 21 on channel CH-x, while terminals 102 to 104 receive the transmitted data and store the channel selection table in memory 21 (S17, S18, S19, S20), and each terminal 101 to 104 cancels the table sharing mode (S21, S22).

[0043] In this way, all terminals 101 to 104 will perform simplex group communication with the channel selection table stored in memory 21. However, for channel control at each terminal thereafter, as shown in Figure 3, the target channels of the channel selection table, CH-a to CH-h, will be defined as four sets of combined channels, each consisting of two channels from the highest level upwards. In other words, channels CH-a and CH-b are defined as the combined channel CH(A), channels CH-c and CH-d are defined as the combined channel CH(B), channels CH-e and CH-f are defined as the combined channel CH(C), and channels CH-g and CH-h are defined as the combined channel CH(D).

[0044] Furthermore, in this embodiment, the common network channel CH-z is the frequency control channel (CH-31: 422.1875MHz) which, according to the standard specifications for low-power radio stations, is available for use within 0.5 seconds for establishing and adjusting communication in simplex communication, as well as for switching and adjusting frequencies.

[0045] In each wireless communication device (terminals 101 to 104) according to this embodiment, in the receive / standby mode, as shown in Figure 6, the system control unit 15 alternately controls the receiving channel of the receive demodulation unit RX2 so that the scan time on the [subchannel] is 50 msec and the scan time on the [common channel: CH-z] is 350 msec. Here, the subchannel is defined in relation to the current channel. The current channel is set as the transmission / reception channel for group communication, configured for the modulation transmitter TX1 and the receiver / demodulator RX1. In contrast, the subchannel is set as the other channel in the same combination channel as the current channel.

[0046] The scan time for the subchannel is the time required to detect whether or not there is interference on that channel, while the scan time for the common channel is to ensure time to receive and detect the channel change request signal [CCR(1)] or the combined channel change request signal [CCR(2)] described later.

[0047] When the wireless communication devices (terminals 101-104) according to this embodiment are used in a group network, a communication frame format as shown in Figure 5 is adopted. The transmitting terminal transmits a modulated wave modulated with MSK (Minimum Shift Keying) or the like using a baseband signal containing voice information incorporated into the format. The receiving terminal demodulates the received signal related to the modulated wave to reproduce the voice signal, while the information incorporated in the data payload is separated and detected and used as data for operation control by the system control unit 15. In this embodiment, the data paylow in the communication frame format includes the local ID (local device identification signal), the G-ID (group identification signal), and transmission channel information, as well as adaptively setting the channel change request signal [CCR(1)] and the combined channel change request signal [CCR(2)].

[0048] Figures 7A, 7B, and 8 show the operating procedures common to each terminal 101-104. First, in the network, as shown in Figure 9, the current channel of each terminal 101 to 104 is initially set to CH-a, and the subchannel is set to CH-b. Therefore, the modulation transmitter TX1 and the receiver demodulator RX1 of each terminal 101 to 104 are set to channel CH-a, and the receiver demodulator RX2 alternately scans subchannel CH-b and common channel CH-z in the manner shown in Figure 6.

[0049] Referring to Figure 7A, if there is no interference on the current channel: CH-a, each terminal 101 to 104 performs group communication in the above state. In the transmit mode with the PTT button of the operation unit 19 turned ON, the modulated carrier signal is transmitted using the input audio signal from the microphone 16. In the receive / standby mode with the PTT button turned OFF, the receive demodulation unit RX1 demodulates the received signal on the current channel: CH-a, obtains an audio playback signal from the demodulated signal and outputs audio from the speaker 14, while the receive demodulation unit RX2 continuously performs alternating scanning of the sub-channel: CH-b and the common channel: CH-z (S31:N→S32). As shown in Figure 9, the network state of the group communication is such that each terminal 101 to 104 can communicate with each other using a simplex method with the current channel: CH-a, and this communication state will continue unless interference occurs on the current channel: CH-a (S33:N→S32).

[0050] However, if interference occurs on the current channel CH-a at any of the terminals (101-104), communication on that channel CH-a will naturally be disrupted. In other words, because it is a simplex system, if carrier sensing detects a busy state, communication cannot be performed until the busy state is resolved. Even if the interference is at a level where it is not detected as a busy state, it will be difficult to hear the voice on the call. For example, as shown in Figure 10, if a communication channel related to another group communication is CH-a and the terminal 101 receives its radio waves, but the group identification signal (G-ID) related to the group communication in this embodiment is "001", while the G-ID confirmed from the demodulated signal of the received radio waves is "002", then interference is naturally considered to occur.

[0051] Therefore, in this embodiment, terminals (101-104) that experience interference on the current channel CH-a in the receiver demodulation unit RX1 immediately check whether interference also occurs on the subchannel CH-b during the alternating scanning process of the receiver demodulation unit RX2. If there is no interference on the subchannel CH-b, the settings of the current channel and subchannel are swapped and changed, and a channel change request signal [CCR(1)] is transmitted from the modulation transmitter TX1 on the swapped current channel CH-b (S33:Y→S34:N→S35,S36).

[0052] Figure 11 shows the network state when interference occurs at terminal 101 and a channel change request signal [CCR(1)] is transmitted. At terminal 101, the current channel is changed to CH-b and the subchannel to CH-a. However, the settings for current channel: CH-a and subchannel: CH-b at terminals 102-104 remain unchanged. Terminals 102-104 receive and demodulate the CCR(1) transmitted from terminal 101 on the current channel: CH-b during the scanning time of subchannel: CH-b in the alternating scan of the receiver / demodulator RX2.

[0053] Then, as shown in the operation procedure in Figure 8 (S51, S52) described later, terminals 102 to 104 swap and change the current channel of the receiver demodulator RX1 and the subchannel of the receiver demodulator RX2 based on the detection of CCR(1). As a result, as shown in Figure 12, the channel setting state of terminals 102 to 104 becomes the same as terminal 101, with the current channel being CH-b and the subchannel being CH-a, and they can automatically switch to group communication using the current channel CH-b to perform a call without interference (S37).

[0054] Group communication on current channel CH-b can continue as with current channel CH-a if no interference occurs (S37, S38:N→S37). However, if interference occurs on current channel CH-b of receiver demodulator RX1, receiver demodulator RX2 immediately checks whether interference is also occurring on subchannel CH-a by alternating scanning (S38:Y→S39). In other words, in step S33, interference occurred on the current channel: CH-a at that time, but subchannel: CH-b was not, so the current channel and subchannel settings were swapped and changed. However, there are many cases where subchannel: CH-a recovers from being in an interfered state to being uninterrupted while group communication is being performed on the current channel: CH-b, so the state of subchannel: CH-a is checked again.

[0055] Then, if the interference is resolved during the status check of subchannel CH-a, the current channel of the receiver / demodulator RX1 and the subchannel setting of the receiver / demodulator RX2 are swapped to return to the original state (current channel: CH-a, subchannel: CH-b), and a channel change request signal [CCR(1)] is transmitted from the modulation transmitter TX1 on the swapped current channel CH-a (S39:N→S40,S41).

[0056] Figure 13 shows the network state when terminal 101 transmits CCR(1) in the aforementioned steps [S37, S38: Y → S39: N → S40, S41]. The CCR(1) transmitted by terminal 101 on the changed current channel: CH-a is received by terminals 102 to 104 during the scanning time of subchannel: CH-a in the receiver demodulator RX2. As shown in the operation procedure in Figure 8 (S51, S52) described later, terminals 102 to 104 swap the current channel of the receiver demodulator RX1 and the subchannel setting of the receiver demodulator RX2, resulting in the same channel setting state as terminal 101, as shown in Figure 14, and the network becomes capable of group communication using the current channel: CH-a.

[0057] Therefore, returning to Figure 7A, according to this embodiment of the invention, even if one of the combined channel CH-a and CH-b of channel CH(A) is experiencing interference, as long as the other is not experiencing interference, group communication can be continued using either channel CH-a or CH-b, which is at the top of the channel selection table in Figure 3, which is sorted in ascending order of channel usage frequency, by swapping and changing the current channel of the receiver / demodulator RX1 and the subchannel of the receiver / demodulator RX2 (S32, S33: Y → S34: N → S35~S38: Y → S39: N → S40, S41 → S32).

[0058] By the way, if interference occurs in any of the combined channels: CH(A)[CH-a,CH-b] at the terminal, in other words, if it is confirmed that both the current channel of the receiver / demodulator RX1 and the subchannels in the alternating scan of the receiver / demodulator RX2 are in an interference state, then immediately check whether the common channel: CH-z in the alternating scan of the receiver / demodulator RX2 is in an interference state (S33:Y→S34:Y→S42, S38:Y→S39:Y→S42). Then, if the common channel: CH-z is free from interference, the modulation transmitter TX1 is temporarily switched to the common channel: CH-z and a combined channel change request signal [CCR(2)] is transmitted (S42:N → S43, S44).

[0059] This CCR(2) declares that since both channels CH-a and CH-b of the combined channel CH(A) are in a state of interference and unusable, the next-highest combined channel CH(B) will be used. However, since combined channel CH(A) is unusable, the common channel CH-z, which is the fixed scan channel in the receiver demodulator RX2 of each terminal 101 to 104, will be used. If the common channel CH-z is experiencing interference, the system will check for interference each time via a 0.4-second waiting period, which is the alternating scanning period of the receiver demodulator RX2 (S42: Y → S42a → S42). However, since the frequency control channel (CH-31), which has a usage time limited to 0.5 seconds, is used here, even if interference occurs, it is expected to recover to an uninterrupted state in a short time, and the transmission of CCR(2) will not be delayed for several seconds.

[0060] Figure 15 shows the network state when interference occurs on both channels of the combined channel: CH(A)[CH-a,CH-b] at terminal 101. Channel: CH-a is being interfered with by radio waves from another group communication (G-ID: 002), and channel: CH-b is being interfered with by radio waves from another group communication (G-ID: 003), making it impossible to use combined channel: CH(A) at terminal 101. Furthermore, Figure 16 shows the network state in which terminal 101 temporarily sets the modulation transmitter TX1 to the common channel: CH-z and transmits CCR(2), while terminals 102 to 104 receive and demodulate CCR(2) during the scanning time of the common channel: CH-z in their alternating scans using the receiver demodulator RX2.

[0061] Now, returning to Figure 7A, terminal 101, which is experiencing interference on both channels of the combined channel CH(A), transmits CCR(2) on the common channel CH-z, and then sets the next combined channel CH(B) in the channel selection table of memory 21 as the current channel and subchannel (S44 → Figure 7B: S45). Specifically, with the current channel being CH-c and the subchannel being CH-d, the current channel CH-c is set for the modulation transmitter TX1 and the receiver demodulator RX1, and the receiver demodulator RX2 is controlled to alternately scan the subchannel CH-d and the common channel CH-z in the manner shown in Figure 6 during the receive / standby mode.

[0062] Figure 17 shows the network state after terminal 101 transmits CCR(2) on the common channel: CH-z in Figure 16. In terminal 101, as described above, the modulation transmission unit TX1 changes from the temporary common channel: CH-z setting to the current channel: CH-c setting, and the receiver demodulation unit RX1 also switches to the current channel: CH-c setting, while the receiver demodulation unit RX2 is set to the alternating scan setting on subchannel: CH-d / common channel: CH-z. Meanwhile, terminals 102 to 104 receive the CCR(2) transmitted by terminal 101 during the scanning time of the common channel CH-z in the cyclic scanning of the receiver / demodulator RX2. By detecting the CCR(2) from the demodulated signal, they change the next combination channel CH(B) in the channel selection table of memory 21 to the current channel and subchannel, as shown in the operation procedure (S53, S54) in Figure 8 described later. As a result, as shown in Figure 17, interference between channels CH-a and CH-b can be avoided, and group communication using the current channel CH-c can be performed by applying a new combined channel CH(B).

[0063] The above explanation mainly focused on the terminal's operation procedure when interference is detected, based on the flowchart in Figure 7 and referring to the network status shown in Figures 9 to 17. Conversely, the operation procedure when the terminal receives a channel change request signal [CCR(1)] or a combined channel change request signal [CCR(2)] (the operation procedure for terminals 102 to 104 in Figures 9 to 17) is shown in Figure 8. The operation procedure shown in Figure 8, as already mentioned in various places in the operation procedure in Figure 7, is defined as an interrupt routine in receive / standby mode.

[0064] If reception of CCR(1) is confirmed during the scanning time of the subchannel in the receiver demodulation unit RX2, the current channels of the modulation transmitter TX1 and receiver demodulation unit RX1 and the subchannels related to the alternating scanning of the receiver demodulation unit RX2 are swapped and changed (S51: Y → S52). This system works by having terminals that experience interference on the current channel but not on the subchannel swap and change their configured channels before sending CCR(1). In response, other terminals that receive CCR(1) also swap and change their current channel and subchannel, so that the channels used in the group communication network are automatically switched to channels without interference.

[0065] On the other hand, if reception of CCR(2) is confirmed during the scanning time of the common channel CH-z in the receiver demodulator RX2, the current channel of the modulation transmitter TX1 and the receiver demodulator RX1 and the subchannel related to the alternating scan of the receiver demodulator RX2 are changed in order to switch the currently used combination channel to the next combination channel (S53:Y→S54). However, the method of changing the channel is also such that the higher channel of the next combination channel is set as the current channel and the lower channel is set as the subchannel. In this case as well, if interference occurs on both channels of the combined channel (current channel and subchannel), the terminal will send CCR(2) on the common channel: CH-z, then set the next highest combined channel in the channel selection table to the current channel and subchannel. Correspondingly, other terminals that receive CCR(2) will also set the next highest combined channel to the current channel and subchannel, so the channel used in the group communication network will start from the higher channel of the new combined channel.

[0066] As described above, when the combined channel: CH(A)[CH-a,CH-b] is applied, if the current channel and subchannel interfere and CCR(2) is transmitted on the common channel: CH-31, the same operation as in steps S32 to S44 is performed with the channel setting in which the combined channel: CH(A)[CH-a,CH-b] is replaced with the combined channel: CH(B)[CH-c,CH-d] (S44→Figure 7B:S45).

[0067] Then, as shown in Figure 7B, if interference occurs on both the current channel and the subchannel, the operation in steps S32 to S44 is performed with a channel setting that replaces the current combination channel with the next-highest combination channel, and the channels used are downgraded, such as combination channel: CH(B)[CH-c,CH-d] → combination channel: CH(C)[CH-e,CH-f] → combination channel: CH(D)[CH-g,CH-h], while automatically maintaining group communication on the least frequently used channel in the channel selection table as much as possible (S45 to S47).

[0068] By the way, in the above explanation, since terminals 101 to 104 are specified low-power radio stations (channel spacing 12.5 kHz), the frequency control channel CH-31 is used as the common channel CH-z. As mentioned above, the usage time of this channel CH-31 is limited, so even if interference occurs, it recovers to a non-interfering state in a short time, which is an advantage that is utilized. This is also true in the case of digital specified low-power radio stations (channel spacing 6.25 kHz / 4-level FSK digital system), in which case the frequency control channel CH-C1 (422.184375 MHz) or CH-C2 (422.190625 MHz) can be used as the common channel CH-z.

[0069] On the other hand, in the case of digital simple radio stations, there are no channels equivalent to the frequency control channels in specified low-power radio stations, but both licensed and registered stations have a far greater number of available channels compared to specified low-power radio stations. Therefore, for example, based on the usage frequency information stored in memory 21 for the 103 channels available at the licensed station, 21 channels are selected in ascending order of usage frequency, and one of these channels (for example, one of the top 3 channels) is selected as the common channel: CH-z, while the other 20 channels are defined as channels to be used, and each combination channel is used starting from the highest combination channel as the current channel and subchannel.

[0070] In that case, since digital simple radio stations inherently have a large number of available channels, there is a high probability that a rarely used channel will be selected. This allows for quick and stable channel changes in the combination without the carrier sense becoming busy when using the common channel: CH-z. [Industrial applicability]

[0071] This invention is used as a wireless communication device and wireless communication network system that realizes an automatic channel change function in the event of interference from external radio waves in a group communication network composed of wireless communication devices conforming to specific low-power standards or digital simple wireless standards. [Explanation of symbols]

[0072] 10...Antenna, 11...Distributor, 12...Amplifier, 13...Amplifier, 14...Speaker (or earphone), 15...System control unit, 16...Microphone, 17...Amplifier, 18...Amplifier, 19...Operation unit, 20...Display unit, 21...Memory, TX1...Modulation transmission unit, RX1...Receiver / demodulator, RX2...Receiver / demodulator, 101, 102, 103, 104...Terminals.

Claims

1. A wireless communication device comprising a transmitting / receiving unit consisting of a modulation transmitting unit and a first receiving / demodulating unit, a second receiving / demodulating unit and a control unit that controls their operation, and a data storage unit, which forms a group network with other wireless communication devices of the same configuration and performs simplex group communication, The data storage unit stores all or a predetermined number of channel information, ranked in ascending order based on the frequency of use over a certain period of time in the past, for all or some of the channels that are available for use for communication in accordance with the radio station standard, as a channel selection table. The channel selection table is defined as having N sets of combination channels (N is an integer of 2 or more) divided into groups of two channels from the top, and these N sets of combination channels are used sequentially starting from the highest-ranking combination. In the receive / standby mode, the first receive demodulation unit is set to one of the combination channels as the current channel for transmitting and receiving the group communication (hereinafter referred to as the "current channel"), and its demodulated signal is reproduced as audio. Meanwhile, the second receive demodulation unit is controlled to alternately scan the other channel of the combination channel (hereinafter referred to as the "subchannel") and the frequency control channel defined in the radio station standard (hereinafter referred to as the "common channel") so that a received demodulated signal can be obtained for each of the scanned channels. When interference in the current channel is detected by the first receiver / demodulator, and interference in the subchannel is not detected by the second receiver / demodulator, a first control procedure is performed in which the current channel and the subchannel's set channels are swapped, and a first channel change request signal is transmitted from the modulation transmission unit on the swapped current channel. When interference in the current channel is detected in the first receiver / demodulator, and interference in the subchannel is detected in the second receiver / demodulator, a second control procedure is performed to temporarily switch the modulation transmission unit to the common channel and transmit a second channel change request signal, and to change the current channel and the subchannel to the channels related to the next-level combination channel, respectively. When the second receiver / demodulator receives the first channel change request signal transmitted by the other wireless communication device during the scanning process of the subchannel, a third control procedure is performed to swap and change the current channel and the setting channels of the subchannels. When the second receiver / demodulator receives the second channel change request signal transmitted by the other wireless communication device during the scanning process of the shared channel by the second receiver / demodulator, a fourth control procedure is performed to change the current channel and the subchannel to the channels corresponding to the next-ranked combination channel in the channel selection table, respectively. A wireless communication device characterized by performing the following actions.

2. A wireless communication device comprising a transmitting / receiving unit consisting of a modulation transmitting unit and a first receiving / demodulating unit, a second receiving / demodulating unit and a control unit that controls their operation, and a data storage unit, which forms a group network with other wireless communication devices of the same configuration and performs simplex group communication, The data storage unit stores all or a predetermined number of channel information, ranked in ascending order based on the frequency of use over a certain period of time, for all or some of the channels that are available for use for communication in accordance with the radio station standard, as a channel selection table. For the top (2 * N + 1) channels (where N is an integer greater than or equal to 2) in the channel selection table, one channel is defined as a common channel, and the remaining channels are defined as N sets of combined channels, each consisting of two channels from top to bottom. These N sets of combined channels are used sequentially, starting with the highest-ranking combination. In the receive / standby mode, the first receive / demodulate unit is set to one of the combination channels as the current channel for transmitting and receiving the group communication (hereinafter referred to as the "current channel"), and its demodulated signal is reproduced as audio. Meanwhile, the second receive / demodulate unit is controlled to alternately scan the other channel of the combination channel (hereinafter referred to as the "subchannel") and the common channel so that a receive / demodulated signal is obtained for each scanned channel. When interference in the current channel is detected by the first receiver / demodulator, and interference in the subchannel is not detected by the second receiver / demodulator, a first control procedure is performed in which the current channel and the subchannel's set channels are swapped, and a first channel change request signal is transmitted from the modulation transmission unit on the swapped current channel. When interference in the current channel is detected in the first receiver / demodulator, and interference in the subchannel is detected in the second receiver / demodulator, a second control procedure is performed to temporarily switch the modulation transmission unit to the common channel and transmit a second channel change request signal, and to change the current channel and the subchannel to the channels related to the next-level combination channel, respectively. When the second receiver / demodulator receives the first channel change request signal transmitted by the other wireless communication device during the scanning process of the subchannel, a third control procedure is performed to swap and change the current channel and the setting channels of the subchannels. When the second receiver / demodulator receives the second channel change request signal transmitted by the other wireless communication device during the scanning process of the shared channel by the second receiver / demodulator, a fourth control procedure is performed to change the current channel and the subchannel to the channels corresponding to the next-ranked combination channel in the channel selection table, respectively. A wireless communication device characterized by performing the following actions.

3. The wireless communication device according to claim 1 or 2, wherein the alternating scanning of the subchannel and the common channel by the second receive demodulation unit in the receive / standby mode is performed with the scanning time of the subchannel set to several tens of ms and the period of the alternating scanning set to within the range of 200 ms to 600 ms.

4. The wireless communication device according to claim 1 or 2, wherein when the highest-ranking combination channel in the channel selection table is set to the current channel and the subchannel at the start of the group communication, and when the current channel and the subchannel are changed to the next-ranking combination channel in the channel selection table upon receiving the second channel change request signal, the higher-ranking channel is set to the current channel side and the lower-ranking channel is set to the subchannel side.

5. The wireless communication device according to claim 1 or 2, wherein when transmitting the first channel change request signal or the second channel change request signal from the modulation transmitting unit, the group identification information of the group network is always included in the transmission.

6. A wireless communication network system in which each terminal of a group communication network is a wireless communication device according to claim 1 or 2, If any of the constituent terminals detects interference in the current channel at the first receive-demodulate unit, and does not detect interference in the subchannel at the second receive-demodulate unit, the current channel and the subchannel's respective setting channels are swapped, and the modulation transmission unit transmits the first channel change request signal on the swapped current channel. If the subchannel's interference is detected at the second receive-demodulate unit, the modulation transmission unit is temporarily switched to the common channel and a second channel change request signal is transmitted, and the current channel and the subchannel are changed to the channels corresponding to the next-level combination channel. If any of the other component terminals receives the first channel change request signal during the scanning process of the subchannel by the second receiver / demodulator, it swaps and changes the current channel and the subchannel's respective set channels. If the second receiver / demodulator receives the second channel change request signal during the scanning process of the shared channel by the second receiver / demodulator, it changes the current channel and the subchannel to the channels corresponding to the next-ranked combination channel in the channel selection table. A wireless communication network system characterized by the following features.

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