Wireless communication device, wireless communication method, and wireless communication system

Abstract

Provided is a wireless communication device that avoids signal collision associated with relaying wireless signals. The wireless communication device includes a plurality of wireless communication modules NIC-1 and NIC-2 that use mutually interfering channels. A repeater SoC 12 is provided with a control circuit that instructs each of the NIC-1 and NIC-2 a rule of waiting time. The NIC-1 and NIC-2 belong to different communication groups 32 and 34, respectively, execute communication processing for wireless communication with a master device 14 or slave devices 16, and relay packets between the NIC-1 and NIC-2. The communication processing includes a process for starting packet transmission, after detecting an idle state by carrier sensing, when the idle state is maintained after the waiting time has elapsed, and a process for setting the waiting time in accordance with the rule. The rule is instructed differently for each of the plurality of wireless communication modules.

Description

[Technical Field]

[0001] The present disclosure relates to a wireless communication device, a wireless communication method, and a wireless communication system, and more particularly to a wireless communication device, a wireless communication method, and a wireless communication system that are suitable for avoiding signal collisions that accompany relaying of wireless signals. [Background technology]

[0002] In the field of wireless communications, wireless signal repeaters are often used to expand communication areas. A repeater typically contains two wireless modules, each of which communicates with terminals in different areas. By forwarding received packets within the repeater to these two wireless modules, communication between terminals in different areas can be established.

[0003] To use two wireless modules in the same housing, it is necessary to avoid reception failures due to interference. For example, if one module is performing reception processing while the other module is performing transmission processing, reception will fail due to the influence of interference, so it is necessary to avoid this situation from occurring.

[0004] Furthermore, if a terminal communicating with one wireless module and a terminal communicating with the other wireless module become hidden terminals, a collision of received signals may occur at the repeater. Furthermore, in this case, if two wireless modules simultaneously perform transmission processing, both transmissions may end in failure. When two wireless modules are used in a repeater, it is necessary to avoid such a situation.

[0005] One method proposed to avoid this situation is to separate frequencies to avoid interference. For example, if two wireless modules use frequency channels that are sufficiently separated, the above-mentioned collision of wireless signals can be completely avoided.

[0006] Alternatively, avoidance of interference by time separation has been proposed. For example, a method has been proposed for avoiding interference in an environment using the same frequency band by utilizing carrier sense, which is performed before transmission in unlicensed bands. Specifically, by introducing carrier sense that stops transmission from one wireless module while the other is receiving a signal above a certain level, it is possible to prevent interference to some extent caused by one wireless module transmitting while the other is receiving. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] IEEE Standard for Information Technology--Telecommunications and Information Exchange between Systems - Local and Metropolitan Area Networks--Specific Requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Summary of the Invention [Problem to be solved by the invention]

[0008] However, because the number of available frequency channels is limited, even if you try to implement the aforementioned frequency separation, there are cases where the frequencies are far enough apart that it is not possible to prepare channels. In such cases, you have no choice but to use overlapping or adjacent channels. In this case, even if each module uses its own channel by carrier sense, there is a possibility that wireless signal collisions will occur due to power leakage from adjacent channels.

[0009] According to wireless LAN (Local Area Network) regulations, wireless signal transmission continues while carrier sense is being executed and waiting for a time equivalent to the sum of the AIFS (Arbitration Inter Frame Space) time and the random backoff time after the channel goes into an idle state. If the channel remains idle, transmission begins when the random backoff counter is completed. The "AIFS time" is a fixed time calculated as the SIFS (Short Inter Frame Space) time + AIFSN (AIFS Number) * slot time. The "random backoff time" is a value calculated as the randomly selected backoff counter * slot time.

[0010] Figure 1 shows a timing chart for explaining the operation when two wireless communication modules, NIC-1 (Network Interface Card or Network Interface Controller) and NIC-2, housed in the same housing, complete counting with the same backoff counter value. In this case, the random backoff ends at the same time, and NIC-1 and NIC-2 start transmitting at the same time. As a result, the transmitted signals interfere with each other, and reception at the terminal fails for both destinations.

[0011] In the example shown in Figure 1, if the counter values ​​used by the two wireless communication modules NIC-1 and NIC-2 are different, a discrepancy will occur in the planned transmission timing, causing one module to start transmitting first. In this case, the other module will determine that the channel is busy using its carrier sense function and will stop transmitting. As a result, wireless signal collisions can be avoided.

[0012] Figure 2 shows a timing chart for explaining the operation when a wireless communication base station in one area and a wireless communication terminal in another area start transmitting at the same time. Even if the two devices that start transmitting at the same time are not housed in the same housing, in the case shown in Figure 2, interference occurs in the repeater between the signals that NIC-1 and NIC-2 should receive, and reception may fail on both.

[0013] In particular, in the field of communications, restrictions are sometimes imposed on the time rate at which transmissions can be made. For example, in the 920 MHz band in Japan, the transmission time is limited to 360 seconds per hour. In such an environment, retransmissions due to reception failures directly affect communication capacity, making them a significant issue.

[0014] Furthermore, a repeater that relays packets received from a terminal in one area to a terminal in another area needs to transmit the received packets. In a situation where a large number of wireless frames are received from multiple wireless communication slave devices, the transmission time is limited and it may not be possible to transmit all packets, resulting in congestion of transmitted packets.

[0015] In this way, in conventional repeaters, collisions of wireless signals can cause transmission failures due to interference and congestion of transmission packets. If both of these occur, communication quality will be significantly degraded.

[0016] The present disclosure has been made in consideration of the above-mentioned problems, and has as its first object to provide a wireless communication device that can stagger the timing of transmission start so as to prevent simultaneous transmission in multiple communications that use channels that interfere with each other.

[0017] A second object of the present disclosure is to provide a wireless communication method for staggering the timing of transmission start so that simultaneous transmission does not occur in a plurality of communications using channels that interfere with each other.

[0018] A third object of the present disclosure is to provide a wireless communication system that can stagger the timing of transmission start so that simultaneous transmission does not occur in multiple communications that use channels that interfere with each other. [Means for solving the problem]

[0019] In order to achieve the above object, a first aspect is a wireless communication device, a plurality of wireless communication modules using channels that interfere with each other; a control circuit that instructs each of the plurality of wireless communication modules on a rule for setting a standby time; each of the plurality of wireless communication modules belongs to a different communication group, and is configured to execute a communication process for wirelessly communicating with a different communication device, thereby relaying packets between a communication device belonging to one communication group and a communication device belonging to another communication group; the communication process includes: detecting an idle state by carrier sense, and then starting packet transmission if the idle state is maintained after the waiting time has elapsed; and setting the waiting time in accordance with the rule; It is desirable that different rules are instructed for each of the plurality of wireless communication modules.

[0020] A second aspect is a wireless communication method using a wireless communication device including a plurality of wireless communication modules that use channels that interfere with each other, and a plurality of communication devices that wirelessly communicate with each of the plurality of wireless communication modules, instructing each of the plurality of wireless communication modules according to a rule for setting a standby time; forming different communication groups by each of the plurality of wireless communication modules wirelessly communicating with different communication devices; each of the plurality of wireless communication modules relaying a packet between a communication device belonging to one communication group and a communication device belonging to another communication group; a step of, after each of the plurality of wireless communication modules detects an idle state by carrier sense, starting transmission of a packet if the idle state is maintained after the waiting time has elapsed; each of the plurality of wireless communication modules setting the standby time in accordance with the rule; It is desirable that different rules are instructed for each of the plurality of wireless communication modules.

[0021] A third aspect is a wireless communication system including a wireless communication device including a plurality of wireless communication modules that use channels that interfere with each other, and a plurality of communication devices that wirelessly communicate with each of the plurality of wireless communication modules, a control circuit for instructing each of the plurality of wireless communication modules on a rule for setting a standby time; Each of the plurality of wireless communication modules By communicating wirelessly with different communication devices, different communication groups are formed, relaying packets between communication devices belonging to one communication group and communication devices belonging to another communication group; After detecting an idle state by carrier sense, if the idle state is maintained after the waiting time has elapsed, start transmitting packets; and configured to set the waiting time according to the rule; It is desirable that different rules are instructed for each of the plurality of wireless communication modules. [Effects of the Invention]

[0022] According to the first to third aspects, the estimated time until transmission, which is counted when a channel is in an idle state as a result of carrier sensing, can be shifted for each communication group. As a result, it is possible to prevent multiple communication groups using interfering channels from starting transmission simultaneously after performing carrier sensing. Therefore, according to the first to third aspects, it is possible to reduce the risk of wireless signal interference and improve communication throughput. [Brief explanation of the drawings]

[0023] [Figure 1] 10 shows a timing chart for explaining the operation when two wireless communication modules NIC-1 and NIC-2 housed in the same housing complete counting with the same back-off counter value. [Figure 2] 10 is a timing chart for explaining the operation when a wireless communication master device belonging to one area and a wireless communication slave device belonging to another area start transmission at the same timing. [Figure 3] 1 is a block diagram showing a basic configuration of a wireless communication system according to a first embodiment of the present disclosure. [Figure 4] FIG. 4 is a block diagram showing a detailed configuration of the wireless communication repeater shown in FIG. 3. [Figure 5] FIG. 4 is a diagram showing two wireless groups formed in the wireless communication system shown in FIG. [Figure 6] FIG. 10 is a diagram showing a list of parameters such as AIFSN determined according to access category (AC). [Figure 7] 11 is a flowchart illustrating a characteristic operation of the wireless communication repeater according to the third embodiment of the present disclosure. [Figure 8] 13 is a flowchart illustrating another example of a characteristic operation of the wireless communication repeater according to the third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0024] Embodiment 1 [Configuration of the First Embodiment] Fig. 3 is a block diagram showing a basic configuration of a wireless communication system according to a first embodiment of the present disclosure. As shown in Fig. 3, the wireless communication system according to this embodiment includes a wireless communication repeater 10. The wireless communication repeater 10 includes a repeater SoC (System on Chip) 12. The repeater SoC 12 is an integrated circuit for transferring packets between a first wireless communication module NIC-1 (hereinafter simply referred to as NIC-1) and a second wireless communication module NIC-2 (hereinafter simply referred to as NIC-2). The repeater SoC 12 is equipped with various elements, such as a processor and a memory, required to realize the above functions.

[0025] NIC-1 is a wireless communication module for performing wireless communication with a wireless communication master device 14. On the other hand, NIC-2 is a wireless communication module for performing wireless communication with a wireless communication slave device 16. The wireless communication system of this embodiment includes the master device 14 and the slave device 16, and may include multiple slave devices 16. The master device 14 and the slave device 16 are far enough apart that direct communication is not possible, but they can communicate with each other via the wireless communication repeater 10.

[0026] Fig. 4 is a block diagram for explaining the configuration of the wireless communication repeater 10 in more detail. As shown in Fig. 4, the wireless communication repeater 10 includes a communication bus 18. A control circuit 20 and a memory 22 are connected to the communication bus 18. A control program and management information are stored in the memory 22. The control circuit 20 includes a processor, and is realized by the processor executing processing in accordance with the control program using the management information and the like. The control program can be provided via a computer-readable recording medium, or via a network.

[0027] A wired communication module 24 and a drive circuit 26 are also connected to the communication bus 18. The wireless communication repeater 10 can establish wired communication with an external device via the wired communication module 24. The drive circuit 26 also has a built-in storage medium for storing various data.

[0028] A user interface 28 and a timer 30 are also connected to the communication bus 18. The user interface 28 is used for various input operations to the wireless communication repeater 10. The timer 30 is used for counting the waiting time during carrier sensing, etc.

[0029] 3 are further connected to the communication bus 18. As described above, the NIC-1 is a wireless communication module for establishing wireless communication between the wireless communication repeater 10 and the parent device 14. On the other hand, the NIC-2 is a wireless communication module for establishing wireless communication between the wireless communication repeater 10 and the child device 16.

[0030] When starting wireless transmission, NIC-1 and NIC-2 perform carrier sensing according to the IEEE 802.11 Distributed Coordination Function (DCF), an access control standard. Specifically, once carrier sensing becomes idle, carrier sensing continues until a waiting time equivalent to the sum of the AIFS time and the random backoff time has elapsed, and if the idle state is maintained at that time, packet transmission begins (see Figure 1).

[0031] According to the DCF, the random backoff time reflects the priority of the packet to be transmitted. Specifically, NIC-1 and NIC-2 randomly select a backoff value from a natural number ranging from 0 to CWmin (Contention Window Minimum) according to the priority of the packet to be transmitted. The upper limit of the backoff value is extended up to CWmax (Contention Window Maximum) depending on the number of retransmissions following a communication failure.

[0032] [Features of the first embodiment] NIC-1 and NIC-2 each randomly select a backoff value. If both NICs freely select backoff values ​​without any constraints, there is a certain probability that the values ​​will match. If the backoff values ​​of both NICs match, a collision will occur between the transmissions of NIC-1 and NIC-2, as explained with reference to Figure 1.

[0033] In this embodiment, in order to avoid such communication collisions, when there are multiple communication groups using interfering channels, a population of random values ​​is set for each of these groups. In other words, the population on which one communication group bases its random values ​​and the population on which another communication group bases their random values ​​are set so that they do not contain overlapping values.

[0034] More specifically, in this embodiment, NIC-1 and NIC-2 communicate using interfering channels within the same chassis. Therefore, it is assumed that there are two communication groups using interfering channels. NIC-1 and NIC-2 are each randomly selected backoff values ​​from a population of even or odd numbers, rather than from a population of natural numbers.

[0035] Here, as an example, NIC-1 is made to select an even backoff value, and NIC-2 is made to select an odd backoff value. Such settings can be realized by issuing commands from control circuit 20 to NIC-1 and NIC-2, which have the function of selecting random backoff values. This restriction can reliably prevent the backoff value selected by NIC-1 and the backoff value selected by NIC-2 from being the same.

[0036] 5 shows two communication groups 32, 34 formed in the wireless communication system of this embodiment. In this embodiment, restrictions on backoff values ​​are imposed on the parent device 14 that communicates with NIC-1 and the child device 16 that communicates with NIC-2. That is, the parent device 14 is required to select a backoff value from a population of even numbers, just like NIC-1. On the other hand, NIC-2 is required to select a backoff value from a population of odd numbers.

[0037] These requests are issued from NIC-1 or NIC-2 to the parent device 14 or child device 16, respectively, as the communication partner, in accordance with instructions from the control circuit 20. The communication devices used in this embodiment, such as the parent device 14 and child device 16, have the function of appropriately setting parameters for the waiting time associated with carrier sensing in response to such requests.

[0038] Thus, in this embodiment, communication group 32 including NIC-1 and parent device 14 is required to set a randomly selected even number as its backoff value. On the other hand, communication group 34 including NIC-2 and child device 16 is required to set a randomly selected odd number as its backoff value. If each of communication groups 32 and 34 selects a random value according to the above rules, collisions of wireless signals between these groups can be reliably avoided.

[0039] [Modification of the first embodiment] In the first embodiment described above, it is assumed that the number of communication groups using interfering channels is two. However, it is also assumed that the wireless communication environment is one in which three or more communication groups establish wireless communication in a mesh pattern. The present disclosure can be applied to such an environment.

[0040] That is, by generally extending the disclosure of the first embodiment, it is assumed that the number of communication groups using interfering channels is n (n is a natural number of 2 or more). In this case, it is required that the k-th communication group has an arithmetic progression expressed as B=m×n+k as the population of random values, where k is a natural number from 1 to n and m is a natural number of 0 or more.

[0041] For example, when the number of communication groups is n=3, the following occurs: Group k=1: The population is the geometric examples 1, 4, 7, 10, 13... Group k=2: The population is the geometric sequence 2, 5, 8, 11, 14... Group k=3: The population is the geometric sequence 3, 6, 9, 12, 15...

[0042] A generalized function of the above modification can be realized by having the communication modules or communication terminals belonging to each communication group select random backoff values ​​according to the restrictions imposed on each communication group. This function ensures that the waiting times for all communication groups are different. Therefore, it is possible to reliably avoid wireless signal collisions for all communication groups.

[0043] Embodiment 2 Next, a second embodiment of the present disclosure will be described with reference to FIG. 6 as well as FIGS. 3 to 5. The wireless communication system of this embodiment can be realized by the hardware configuration shown in Figures 3 and 4, as in the case of embodiment 1. Also in this embodiment, as shown in Figure 5, the standby times of communication group 32 and communication group 34 are set so that they are not the same value.

[0044] As described above, according to the DCF of IEEE 802.11, the sum of the AIFS time and the random backoff time is set as the standby time during carrier sensing. In the first embodiment described above, collisions of wireless signals are avoided by avoiding overlaps between random backoff times between communication groups. In this embodiment, a similar function is achieved by avoiding overlaps between AIFS times.

[0045] As described above, the AIFS time is calculated as "SIFS time + AIFSN * slot time." The AIFSN is a parameter determined according to the access category of the communication, etc. More specifically, in this embodiment, the AIFSN value is set to a different value for each communication group to prevent the waiting times from becoming the same.

[0046] Fig. 6 shows a list of parameters such as AIFSN determined according to the access category (AC). The values ​​shown in the list are general rules defined by IEEE. For example, if the packet priority is AC_BE (Access Category Best Effort), the AIFSN is normally 3, as shown in Fig. 6. Since NIC-1 and NIC-2 are used to relay the same communication, their access categories are the same. Therefore, in a configuration such as this embodiment, the AIFSN of both devices will normally be the same value.

[0047] In contrast, in this embodiment, the AIFSNs of the communication group 32 including NIC-1 and the parent device 14 are set to different values, for example, the AIFSN of the communication group 32 including NIC-1 and the parent device 14 is set to 3, while the AIFSN of the communication group 34 including NIC-2 and the child device 16 is set to 7. Although this depends on the length of the random backoff time, the smaller the AIFSN, the shorter the standby time tends to be. Therefore, under the above settings, there is a high possibility that the standby time of the communication group 32 will elapse more quickly than the standby time of the communication group 34.

[0048] Specifically, assuming that CWmin is 15, the backoff value is selected in the range of 0 to 15. Although detailed calculations are omitted, in this case, the probability that communication group 32, whose AIFSN is 3, will start transmission before communication group 34 is approximately 70%. The probability that the two communication groups 32 and 34 will start transmission simultaneously is reduced from 6.25% to 4.7% compared to when the AIFSNs are the same value.

[0049] In this manner, in this embodiment, the AIFSN is set to a different value for each of multiple communication groups that handle the same communication. As a result, in this embodiment, the probability that multiple communication groups will start transmission simultaneously can be reduced compared to when the AIFSNs have the same value. Therefore, according to the wireless communication system of this embodiment, as in the first embodiment, signal collisions between communication groups can be reduced, thereby increasing the overall communication throughput.

[0050] [Modification of the second embodiment] Some wireless communication standards require individual wireless devices to have a pause time after completing transmission. For example, in the 920 MHz band in Japan, a pause time of 2 msec or more may be required after transmission depending on the transmitting side's conditions. In such cases, it may be possible to set different pause times for each communication group, even though this may result in a longer pause time than necessary. For example, the pause time for communication group 32 may be set to 2 msec, while the pause time for communication group 34 may be set to 2.5 msec. By setting different pause times for each communication group in this way, the start times of the standby times are staggered, significantly reducing the possibility of collisions between communication groups. Note that the technique of setting different pause times may be combined with the technique of setting different AIFSNs, or may be used independently.

[0051] Although the second embodiment described above illustrates a case where there are two communication groups, the present disclosure is not limited to this. As in the case described in the modified example of the first embodiment, when three or more communication groups establish communication in a mesh pattern, the same effect as described above can be obtained by setting parameters such as AIFSN and pause time to different values ​​for each group.

[0052] Embodiment 3 Next, a third embodiment of the present disclosure will be described with reference to FIG. 7 as well as FIGS. 3 to 5. FIG. The wireless communication system of this embodiment can be realized by the hardware configuration shown in Figures 3 and 4, as in the case of embodiment 1. Also in this embodiment, as shown in Figure 5, the standby times of communication group 32 and communication group 34 are set so that they are not the same value.

[0053] In the second embodiment described above, the probability that the standby times end simultaneously is reduced by setting different AIFSN values ​​for each communication group. In this case, as described above, a communication group with a small AIFSN value will have a higher probability of starting transmission before a group with a large AIFSN value. In other words, a communication group with a small AIFSN value will be given preferential treatment in obtaining the transmission right.

[0054] Similar preferential treatment occurs depending on the length of the pause time, as explained in the modified example of the second embodiment. Specifically, a communication group whose pause time is set to 2 msec will have a higher probability of starting communication before a group whose pause time is set to 2.5 msec. Furthermore, if the CWmin, which determines the upper limit of the random backoff value, is set to a different value for each communication group, a group with a smaller CWmin will be given preferential treatment.

[0055] In this embodiment, multiple slave devices 16 are wirelessly connected to NIC-2. Therefore, NIC-2 transfers packets uploaded from the multiple slave devices 16 to NIC-1. NIC-1 must then upload all of these packets to the master device 14 via the wireless section. In this configuration, packet congestion is likely to occur in NIC-1. Therefore, if preferential settings are applied to the communication group 32 that includes NIC-1, the occurrence of congestion can be suppressed.

[0056] However, if the preferential setting for the communication group 32 continues permanently, a situation may arise in which packet congestion occurs in the communication group 34. Therefore, in this embodiment, in addition to differentiating the setting parameters of the waiting time for each communication group using the method described in the first or second embodiment, the setting for preferential treatment for the communication group 32 and the setting for preferential treatment for the communication group 34 are alternately switched.

[0057] 7 is a flowchart for explaining the flow of a routine executed in the control circuit 20 of the wireless communication repeater 10 to realize the above function. This routine is executed repeatedly after communication via the wireless communication repeater 10 is started.

[0058] 7, first, processing required for wireless communication transmission is executed (step 100). Specifically, processing is executed to cause the relay device SoC12 to relay packets between NIC-1 and NIC-2. If initial setting is required, in step 100, parameters of waiting times are set for the two communication groups 32 and 34 so that preferential setting is applied to the communication group 32.

[0059] Next, a process is executed to measure the traffic volume or communication quality for each of the communication groups 32 and 34 (step 102).

[0060] Next, based on the measurement results, it is determined whether a reversal has occurred in the communication group in which congestion is predicted (step 104). In the initial setting, it is determined that congestion is likely to occur in communication group 32, which includes NIC-1. If the initial setting is maintained, it is determined whether the group in which congestion is predicted to occur has changed from communication group 32 to communication group 34. On the other hand, if the prediction has already been switched, it is determined whether the group in which congestion is predicted to occur has changed from communication group 34 to communication group 32.

[0061] If it is determined in step 104 that no prediction reversal has occurred, the current routine is terminated. In this case, the preferential setting is maintained as is. On the other hand, if a prediction reversal has occurred, the parameter setting of the waiting time is reversed so that preferential setting is given to communication groups that are prone to congestion (step 106).

[0062] According to the above process, it is possible to appropriately provide preferential treatment to communication groups where congestion is predicted, while maintaining a state in which the probability that the waiting times will end simultaneously is reduced. Therefore, according to the wireless communication system of this embodiment, it is possible to stably maintain high throughput without causing packet congestion.

[0063] [Modification of the third embodiment] In the third embodiment described above, the communication group to which the preferential setting is applied is switched when the congestion prediction is reversed. However, the timing of the switch is not limited to this. In other words, in order to ensure the stability of control and to provide a hysteresis characteristic to the switch of the preferential setting, the switch may be performed when the difference in the congestion prediction values ​​exceeds a predetermined threshold.

[0064] In the third embodiment described above, the traffic volume and communication quality are measured for each communication group, and the target of the preferential setting is switched based on the results. However, the present disclosure is not limited to this. For example, the measurement of communication quality and the like may be omitted, and the target of the preferential setting may be switched between the communication group 32 and the communication group 34 at regular intervals.

[0065] 8 is a flowchart for explaining the flow of a routine executed in the control circuit 20 of the wireless communication repeater 10 when switching the target to which preferential setting is applied at regular intervals. In this routine, first, preferential setting is applied to the communication group 32 for which the occurrence of congestion is structurally predicted (step 110).

[0066] Then, after a certain "preferential treatment time" has elapsed (step 112), the preferential treatment setting is cancelled, and with this cancellation, the communication group 34 is switched to a preferential treatment setting (step 114).

[0067] Furthermore, when the "preferential treatment release time" during which the communication group 34 should be given preferential treatment has elapsed (step 116), the current routine is terminated. Then, step 110 is executed again, thereby restoring the state in which the communication group 32 is given preferential treatment. At this time, if the "preferential treatment time" during which the communication group 32 is given preferential treatment is set longer than the "preferential treatment release time," it is possible to reduce the control load compared to when the routine shown in Fig. 7 is used, and to suppress the occurrence of congestion in the wireless communication system in a long-term and stable manner.

[0068] Although the above-described third embodiment illustrates a case where there are two communication groups, the present disclosure is not limited to this. As in the case described in the modified examples of the first and second embodiments, when three or more communication groups establish communication in a mesh pattern, the target to which preferential setting is applied can be switched between the groups in sequence to obtain the same effect as described above.

[0069] Furthermore, in the above-described first embodiment, the probability that the standby times end simultaneously is reduced by using different populations when selecting the random backoff times. In the second embodiment, the same effect is achieved by using different values ​​for the AIFSN or the sleep time. In other words, the present disclosure provides a technology for reducing the frequency of wireless signal collisions in multiple communication groups by using different rules for setting the standby times. [Explanation of symbols]

[0070] 10 Wireless communication repeater 12 Repeater SoC (System on Chip) 14 Base unit 16 Handsets 20 Control circuit 22 Memory NIC-1, NIC-2 Wireless communication module (Network Interface Card or Network Interface Controller)

Claims

1. A plurality of wireless communication modules housed in the same housing in a state where wired communication is possible and which use channels that interfere with each other; a control circuit that instructs each of the plurality of wireless communication modules on a rule for setting a standby time; each of the plurality of wireless communication modules belongs to a different communication group, and is configured to execute a communication process for wirelessly communicating with a different communication device, thereby relaying packets between a communication device belonging to one communication group and a communication device belonging to another communication group; the communication process includes: detecting an idle state by carrier sense, and then starting packet transmission if the idle state is maintained after the waiting time has elapsed; and setting the waiting time in accordance with the rule; A wireless communication device in which the rule instructs each of the plurality of wireless communication modules to be different.

2. The process of setting the waiting time includes: Selecting a random backoff time by randomly selecting a number from the population; setting the waiting time to include the random backoff time; the rules include a designation of the population; The wireless communication device according to claim 1 , wherein the control circuit instructs the rule so that different populations are instructed to each of the plurality of wireless communication modules.

3. The process of setting the waiting time includes: A process of selecting a random backoff time by randomly selecting a number; calculating a fixed time based on the parameters; and setting the waiting time to include the random backoff time and the fixed time; the rules include a specification of the parameters; The wireless communication device according to claim 1 , wherein the control circuit instructs the rules so that different parameters are instructed to each of the plurality of wireless communication modules.

4. The fixed time is the AIFS time, which is calculated as SIFS time + AIFSN * slot time, The wireless communication device of claim 3 , wherein the parameter is the AIFSN.

5. the fixed time period includes a pause period provided after the end of transmission; The wireless communication device according to claim 3 , wherein the parameter is the pause time.

6. The wireless communication device according to claim 1 , wherein the control circuit is configured to execute a process of sequentially switching among the plurality of wireless communication modules a target of preferential setting that has a shorter standby time than other wireless communication modules.

7. A wireless communication method using a wireless communication device including a plurality of wireless communication modules housed in the same housing in a state where wired communication is possible and using channels that interfere with each other, and a plurality of communication devices that wirelessly communicate with each of the plurality of wireless communication modules, instructing each of the plurality of wireless communication modules according to a rule for setting a standby time; forming different communication groups by each of the plurality of wireless communication modules wirelessly communicating with different communication devices; each of the plurality of wireless communication modules relaying a packet between a communication device belonging to one communication group and a communication device belonging to another communication group; a step of, after each of the plurality of wireless communication modules detects an idle state by carrier sense, starting transmission of a packet if the idle state is maintained after the waiting time has elapsed; each of the plurality of wireless communication modules setting the standby time in accordance with the rule; A wireless communication method in which the rule instructs different ones of the plurality of wireless communication modules.

8. A wireless communication system comprising: a wireless communication device including a plurality of wireless communication modules housed in the same housing in a state where wired communication is possible and using channels that interfere with each other; and a plurality of communication devices that communicate wirelessly with each of the plurality of wireless communication modules, a control circuit for instructing each of the plurality of wireless communication modules on a rule for setting a standby time; Each of the plurality of wireless communication modules By communicating wirelessly with different communication devices, different communication groups are formed, relaying packets between communication devices belonging to one communication group and communication devices belonging to another communication group; After detecting an idle state by carrier sense, if the idle state is maintained after the waiting time has elapsed, start transmitting packets; and configured to set the waiting time according to the rule; A wireless communication system in which the rules instruct different ones for each of the plurality of wireless communication modules.

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