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

Abstract

The present disclosure relates to a wireless communication system, a wireless communication device, a wireless communication method, and a wireless communication program. This wireless communication system is provided with an AP capable of performing wireless communication using a plurality of links. The AP is configured to execute: a process for acquiring the number of neighboring APs for each available channel; a process for creating an index that ranks the available channels in ascending order of number of neighboring APs; a process for checking whether the number of neighboring APs of each channel is zero in ascending order of rank in the index; a process for assigning a channel to an operational link of the AP if the channel has zero neighboring AP; a process for assigning the channel having the smallest rank to the operational link of the AP if there is no channel having zero neighboring AP and there is no channel assigned to the operational link of the AP; and a process for performing wireless communication using the link assigned with the channel.

Description

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

[0001] The present disclosure relates to a wireless communication system, a wireless communication device, a wireless communication method, and a wireless communication program.

[0002] Non-Patent Document 1 discloses the least congested channel selection (LCCS) method, which is a channel allocation method used by a conventional single link device (SLD) for communication entities. In the LCCS method, in a first step, a channel with less contention is preferentially allocated to a randomly selected access point (AP). Subsequently, in a second step, a channel with less contention is preferentially allocated to a randomly selected AP different from the AP in the first step.

[0003] When the above-mentioned LCCS method is extended to a communication entity of an MLD (Multi Link Device), each of the multiple links used by the MLD is assigned a channel with the least interference. In other words, a channel is assigned to all links used by the MLD. Hereinafter, this method will be referred to as the extended LCCS method.

[0004] The extended LCCS method is an optimal allocation method when there is no possibility that the corresponding communication entity will cause interference to other communication entities. First, because channels are allocated to all links, an increase in communication volume can be expected in proportion to the number of links. Furthermore, even if all links are performing communication, there is no interference with the communication of other communication entities, so there is no problem of a deterioration in the communication characteristics of the entire system.

[0005] Arunesh Mishra, Suman Banerjee, William Arbaugh, “Weighted coloring based channel assignment for WLANs”, ACM SIGMOBILE Mobile Computing and Communications Review, July 2005, Volume 9, Issue 3, pp 19-31

[0006] However, when the above-described extended LCCS method is used in a communication entity that interferes with other communication entities, such as a wireless LAN in a dense environment, there arises a problem that the communication characteristics of the entire system are degraded.

[0007] In order to solve the above-mentioned problems, the first objective of the present disclosure is to provide a wireless communication system that can maximize the communication characteristics of the entire system by suppressing interference with the communications of other communication entities.

[0008] A second object of the present disclosure is to provide a wireless communication device that can maximize the communication characteristics of the entire system by suppressing interference with communications of other communication entities.

[0009] A third object of the present disclosure is to provide a wireless communication method that can maximize the communication characteristics of the entire system by suppressing interference with communications of other communication entities.

[0010] A fourth object of the present disclosure is to provide a wireless communication program that can maximize the communication characteristics of the entire system by suppressing interference with communications of other communication entities.

[0011] A first aspect of the present disclosure is a wireless communication system having an AP that can perform wireless communication using multiple links, wherein the AP is configured to perform the following processes: acquiring the number of neighboring APs for each available channel; creating an index that ranks the available channels in ascending order of the number of neighboring APs; checking whether the number of neighboring APs for a channel in ascending order in the index is zero; if a channel with zero number of neighboring APs exists, assigning the channel to the link used by the AP; if there is no channel with zero number of neighboring APs and no channel has been assigned to the link used by the AP, assigning the channel with the lowest ranking to the link used by the AP; and performing wireless communication using the link to which the channel has been assigned.

[0012] A second aspect of the present disclosure is a wireless communication device capable of performing wireless communication using multiple links, and is preferably configured to perform the following processes: acquiring the number of neighboring APs for each available channel; creating an index that ranks the available channels in ascending order of the number of neighboring APs; checking whether the number of neighboring APs for a channel in ascending order in the index is zero; if a channel with a number of neighboring APs of zero exists, assigning the channel to the link used by the AP; if there is no channel with a number of neighboring APs of zero and there is no channel already assigned to the link used by the AP, assigning the channel with the lowest ranking to the link used by the AP; and performing wireless communication using the link to which the channel has been assigned.

[0013] A third aspect of the present disclosure is preferably a wireless communication method implemented by a wireless communication device capable of performing wireless communication using multiple links, comprising: obtaining the number of neighboring APs for each available channel; creating an index in which the available channels are ranked in ascending order of the number of neighboring APs; checking whether the number of neighboring APs for a channel in ascending order in the index is zero; if a channel with a number of neighboring APs of zero exists, assigning the channel to the link used by the AP; if there is no channel with a number of neighboring APs of zero and there is no channel already assigned to the link used by the AP, assigning the channel with the lowest ranking to the link used by the AP; and performing wireless communication using the link to which the channel has been assigned.

[0014] A fourth aspect of the present disclosure is a wireless communication program that can perform wireless communication using multiple links and is executed by a wireless communication device that has a processor and memory, the wireless communication program being stored in memory and computer-readable, and including a program that causes the processor to perform the following processes: obtaining the number of neighboring APs for each available channel; creating an index that ranks the available channels in ascending order of the number of neighboring APs; checking whether the number of neighboring APs for a channel in ascending order in the index is zero; if a channel with a number of neighboring APs is zero, assigning the channel to the link used by the AP; if there is no channel with a number of neighboring APs is zero and there is no channel already assigned to the link used by the AP, assigning the channel with the lowest ranking to the link used by the AP; and performing wireless communication using the link to which the channel has been assigned.

[0015] According to the first to fourth aspects of the present disclosure, it is possible to maximize the communication characteristics of the entire system by suppressing interference with the communications of other communication entities.

[0016] 1 is a diagram illustrating a configuration of a wireless communication system according to a first embodiment of the present disclosure. FIG. 2 is a first diagram illustrating a hardware configuration of an AP according to the first embodiment of the present disclosure. FIG. 3 is a second diagram illustrating a hardware configuration of an AP according to the first embodiment of the present disclosure. FIG. 4 is a flowchart illustrating a channel allocation process according to the first embodiment of the present disclosure. FIG. 5 is a chart illustrating classification of selection criterion C according to the first embodiment of the present disclosure. FIG. 6 is a flowchart illustrating a process when the channel allocation criterion according to the first embodiment of the present disclosure is the reference AAL. FIG. 7 is a flowchart illustrating a process when the channel allocation criterion according to the first embodiment of the present disclosure is the reference OSL. FIG. 8 is a flowchart illustrating a process when the channel allocation criterion according to the first embodiment of the present disclosure is the reference FLN. FIG. 9 is a diagram illustrating an outline of computer simulation conditions according to the first embodiment of the present disclosure. FIG. 10 is a graph illustrating a relationship between the number of BSSs and average throughput in a computer simulation according to the first embodiment of the present disclosure. FIG. 11 is a graph illustrating a relationship between the number of BSSs and fairness in a simulation according to the first embodiment of the present disclosure. FIG. 12 is a graph illustrating a relationship between the number of BSSs and minimum throughput in a simulation according to the first embodiment of the present disclosure.

[0017] 1 is a diagram illustrating a configuration of a wireless communication system according to a first embodiment of the present disclosure. Here, a wireless communication system 100 according to the first embodiment of the present disclosure includes five BSSs (Basic Service Sets). The wireless communication system 100 is a wireless communication system that uses, for example, 802.11be as a communication standard.

[0018] The wireless communication system 100 includes a BSS 2a. The BSS 2a includes an AP 4a. The AP 4a is an MLD that can perform wireless communication using multiple links. Here, the AP 4a performs wireless communication using three links. The AP 4a performs a channel allocation process, which will be described later, to allocate a channel to at least one of the three links and perform wireless communication.

[0019] This AP 4a performs wireless communication with the wireless communication terminal 6. Here, an aspect is shown in which the BSS 2a has three wireless communication terminals 6 using three links.

[0020] The wireless communication system 100 also includes BSSs 2b to 2e. Similar to the BSS 2a, the BSSs 2b to 2e include APs 4b to 4e. Similar to the AP 4a, the APs 4b to 4e perform wireless communication with three wireless communication terminals 6.

[0021] 2 is a first diagram illustrating a hardware configuration of an AP according to the first embodiment of the present disclosure. FIG. 2 illustrates a configuration in which the functions of the wireless communication device according to the first embodiment of the present disclosure are realized by hardware.

[0022] The AP 4a-1 includes a receiving device 42. The receiving device 42 receives information transmitted from other wireless devices and transmits it to a processing circuit 45. The processing circuit 45 is a dedicated hardware circuit for performing a channel allocation process, which will be described later. The transmitted information is information necessary for the channel allocation process, which will be described later, such as the number of neighboring APs, which will be described later.

[0023] When the channel allocation is determined by the processing of the processing circuit 45, information necessary for the channel allocation is transmitted to the transmitting device 48. The transmitting device 48 performs wireless communication with other wireless communication devices using the channel allocation based on the transmitted information. In other words, the AP 4a-1 can realize functions unique to this embodiment by the processing circuit 45 executing the processing.

[0024] 3 is a second diagram illustrating a hardware configuration of an AP according to the first embodiment of the present disclosure. FIG. 3 illustrates a configuration in which the functions of the wireless communication device according to the first embodiment of the present disclosure are realized by software.

[0025] 2, the AP 4a-2 includes a processor 44 and a memory 46. The memory 46 stores a wireless communication program executed by the processor 44. The AP 4a can realize functions specific to this embodiment by the processor 44 executing the wireless communication program.

[0026] That is, the functions of the AP 4a-2 can be realized by a computer and the program. The program can also be recorded on a recording medium or provided via a network.

[0027] [Channel Allocation Process Performed by AP According to First Embodiment of the Present Disclosure] Figure 4 is a flowchart showing the channel allocation process according to the first embodiment of the present disclosure. First, in step 100, AP selection is performed. This step is a step of selecting an AP that will perform the channel allocation process from among multiple APs included in the wireless communication system. This AP selection may be performed based on, for example, selection criterion C, which will be described later.

[0028] An example of an entity that performs step 100 is a network controller. This network controller is connected to all APs included in the wireless communication system 100 and is capable of transmitting and receiving information to and from each AP. In other words, if the entity that performs step 100 is a network controller, the wireless communication system 100 needs to include a network controller in addition to the configuration shown in FIG. 1 .

[0029] The AP selection can be performed, for example, by the network controller selecting an AP to perform the channel allocation process and notifying the selected AP of the selection result. The selected AP performs the channel allocation process upon receiving the notification. In this example, the network controller does not need to know the location information of all APs.

[0030] If the network controller knows the location information of all APs, it may calculate the AP selection order in advance so that the channel assignment process can be performed most efficiently. Furthermore, the network controller may perform the channel assignment process described below in addition to AP selection. In this case, the network controller notifies the corresponding AP of the AP selection results and the channel assignment results.

[0031] Step 100 may be omitted if the AP performs the channel allocation process independently of other APs. Four examples of the channel allocation process method in this case are given.

[0032] First, an example of a method is that the AP that performed the channel allocation process performs the channel allocation process again after a fixed time or a randomly determined time has elapsed. Second, an example of a method is that the AP that performed the channel allocation process performs the channel allocation process again, triggered by a "time" that was set at the time of purchase.

[0033] A third example is a method in which an AP that has performed a channel allocation process performs the channel allocation process again, triggered by a "change in the number of neighboring APs." The "neighboring APs" are the number of APs competing with the selected AP, and are counted when the distance between APs is equal to or less than the neighboring distance. A "change in the number of neighboring APs" may occur when a neighboring AP changes the channel it uses.

[0034] A fourth example is a method in which an AP that has performed a channel allocation process performs the channel allocation process again, triggered by “information obtained from a neighboring AP.” For example, the AP may perform the channel allocation process again after a certain time or a randomly determined time has elapsed since the neighboring AP received a notification that the channel allocation process has been performed.

[0035] In the fourth example, an AP that does not have neighboring APs cannot receive the triggering notification. However, in this case, the channel allocation process performed by the AP in the present disclosure allows all available channels to be allocated, so no problem occurs. The channel allocation process will be described in detail later.

[0036] In the first to fourth examples, three examples of conditions under which an AP terminates the channel allocation process can be given. First, a method can be exemplified in which the channel allocation process is terminated after a certain time has elapsed since the initial channel allocation process. The certain time may be, for example, a time set when the AP is purchased. The time set here may be determined, for example, by estimating, using a simulation, the time it takes for all APs in the wireless communication system 100 to complete the channel allocation process.

[0037] A second example is a method of terminating the channel allocation process when the "number of neighboring APs" does not change even after the channel allocation process is performed. Note that if the AP is connected to a network controller, the AP may notify the network controller that the "number of neighboring APs" will not change. In this case, the network controller may notify at least one of the connected APs to terminate the channel allocation process.

[0038] A third example is a method in which, when an AP is connected to a network controller, the channel allocation process is terminated upon receiving a notification from the network controller. First, the AP notifies the network controller that it has performed the channel allocation process. The network controller then notifies each AP to terminate the channel allocation process, for example, when each AP has performed the channel allocation process a certain number of times. The AP may terminate the channel allocation process upon receiving this notification.

[0039] Subsequently, in step 102, an allocation process is performed in which the AP selected in the previous step determines the content of channel allocation based on the selected channel allocation criteria.

[0040] There are three examples of channel allocation criteria used here. The first channel allocation criterion is the standard AAL (Always All Links). In the standard AAL, first, from available channels, channels with a small number of neighboring APs are selected for the required number of links. The selected channels are then assigned to all links to be used.

[0041] The second channel allocation criterion is reference OSL (occasionally selected links). In reference OSL, if there is a channel with zero neighboring APs, that channel is assigned to the link to be used. Also, if there is no channel with zero neighboring APs, the channel with the fewest neighboring APs is selected and assigned to the link to be used. In other words, in reference OSL, channels are not necessarily assigned to all links that an AP can use.

[0042] The third channel allocation criterion is the fixed link number (FLN). FLN is the number of links used by the selected AP and can be set freely as long as it is equal to or less than the number of links available to the AP. The fixed FLN is used to first rank available channels in descending order of the number of neighboring APs. Then, the channels with the FLN number are selected in descending order of the number of neighboring APs, and these channels are assigned to the links to be used.

[0043] The first to third channel allocation criteria select channels to be assigned to the link to be used based on the number of neighboring APs. If multiple channels with the same number of neighboring APs are detected, a required number of channels may be randomly selected from the multiple channels.

[0044] There are two examples of methods by which the AP selects the channel allocation criteria in step 102. The first method is to compare the estimated values ​​of communication characteristics according to the channel allocation criteria in real time and select the optimal channel allocation criteria. For example, first, the communication quality when all selectable channel allocation criteria are selected is simulated. Then, by comparing the simulation results, the channel allocation criteria that can maximize the communication characteristics of the entire system is selected. This method is particularly useful when the communication characteristics of the entire system can be simulated in real time.

[0045] The second method is to select a channel allocation standard in advance based on the factors that the entire system prioritizes in terms of communication characteristics. Based on the simulation results described below, the desired effect can be achieved by always selecting the standard AAL when prioritizing total throughput, and the standard OSL when prioritizing maximizing minimum throughput or fairness. This method is particularly useful when the communication characteristics of the entire system can be simulated in advance.

[0046] As described above, the channel allocation criteria selected in the allocation process of step 102 may always be the same, or may be switched depending on the target element in the communication characteristics. For example, by switching the channel allocation criteria depending on the application to be applied, it may be possible to further improve the communication characteristics of the entire system.

[0047] In the allocation process of step 102, the method in which the reference AAL is always selected is hereinafter referred to as the LCCS-AAL method. Similarly, the method in which the reference OSL is always selected is hereinafter referred to as the LCCS-OSL method. Furthermore, the method in which the reference FLN is always selected and the FLN value can be freely set is hereinafter referred to as the LCCS-FLN method.

[0048] Next, channel allocation is performed in step 104. This channel allocation is a process of actually allocating channels to links used by the AP based on the channel allocation content determined in the previous step.

[0049] Next, in step 106, it is confirmed whether or not to adjust the number of channels. This channel number adjustment is a process of further increasing or decreasing the number of channels to be allocated based on the number of channels allocated in the previous step. If adjustment is to be carried out, the process proceeds to step 108. If adjustment is not to be carried out, the channel allocation process is terminated.

[0050] Next, in step 108, the channel number manipulation is performed, and the channel assignment process is terminated. For example, the number of assigned channels may be increased, and new channels may be assigned to links that do not have channels assigned to them. Alternatively, the number of assigned channels may be decreased, and channels already assigned to links may be discontinued. This manipulation allows fine adjustment of the channel assignment.

[0051] 4 may be performed in a batch manner or sequentially, for example, when an AP is added to the wireless communication system 100.

[0052] [Advantages of the channel allocation process according to the first embodiment of the present disclosure] The advantages of the above-described channel allocation process will be explained by comparing it with conventional channel allocation processes. The conventionally used extended LCCS method allocates channels to all links that an AP can use. Therefore, if an AP using the same method interferes with other APs, there is a problem that the communication characteristics of the entire system are degraded.

[0053] For example, consider a wireless communication system #1 in which APs #1, #2, and #3 using the extended LCCS method are arranged in a horizontal line. APs #1 and #3 located at both ends can obtain access rights because only AP #2 is a neighboring AP. However, AP #2 cannot obtain access rights because APs #1 and #3, which have access rights, are neighboring APs. AP #2 in this case is hereinafter referred to as a starving AP.

[0054] Next, consider a wireless communication system #2 in which APs #1, #2, and #3 using the extended LCCS method are located to form an equilateral triangle. In this case, each of the three APs has two neighboring APs, and can obtain access rights to the same extent.

[0055] As described above, when APs constituting a wireless communication system use the extended LCCS method, a starving AP may occur depending on the positional relationship of the APs. In other words, the occurrence of a starving AP depending on the topology of contention may degrade the communication characteristics of the entire system.

[0056] On the other hand, in the channel allocation process according to the first embodiment of the present disclosure, channels are not allocated to all links that can be used by an AP. For example, when the channel allocation criterion is a reference OSL, only channels with zero neighboring APs or channels with the fewest neighboring APs are allocated. Also, when the channel allocation criterion is a reference FLN, only channels with the FLN number of neighboring APs are allocated in ascending order. This can suppress interference with other communication entities, thereby maximizing the communication characteristics of the entire system.

[0057] Furthermore, the channel allocation process according to the first embodiment of the present disclosure can also perform the same channel allocation process as the conventionally used extended LCCS method. For example, if the AP has no neighboring APs, the same channel allocation process as the extended LCCS method can be performed by selecting the reference AAL as the channel allocation criterion. In other words, by appropriately selecting the channel allocation criterion from multiple candidates, the communication characteristics of the entire system can be maximized depending on the situation.

[0058] [Details of Channel Allocation Process According to First Embodiment of the Present Disclosure] Fig. 5 is a chart showing classification of selection criteria C according to the first embodiment of the present disclosure. Selection criteria C is an example of a criterion for selecting an AP to perform the channel allocation process in step 100 of Fig. 4 .

[0059] AP selection may be performed, for example, randomly or regularly. Regular AP selection may be performed, for example, periodically or based on a trigger. Periodic AP selection may be performed, for example, by assigning serial numbers to all APs included in the wireless communication system and changing the AP to be selected in order of serial numbers every time a certain period of time has elapsed.

[0060] Furthermore, when AP selection is performed regularly and based on a trigger, the calculation result of the estimated throughput may be the trigger, or it may be performed based on other triggers such as time. When the calculation result of the estimated throughput is used as the trigger, for example, the estimated throughput of a simple method may be used, or BoE (Back-of-the-Envelope) may be used. The estimated throughput of the simple method may be calculated using the formula, for example, (channel throughput) / (number of neighboring APs + 1). Note that the calculation result of the estimated throughput is used as a trigger only when the estimated throughput of other APs can be referenced, as in the case of a centralized control method.

[0061] 6 is a flowchart showing a process when the channel allocation criterion according to the first embodiment of the present disclosure is the standard AAL. Note that steps having the same content in FIGS. 6 to 8 may be omitted or simplified as appropriate.

[0062] First, AP selection is performed in step 110. This AP selection is the same as the AP selection in step 100 in FIG.

[0063] Next, in step 112, the channel ch is set to 1. Next, in step 114, N_AP(ch) is obtained. N_AP(ch) is the number of neighboring APs in the channel ch of the selected AP.

[0064] Next, in step 116, the channel ch is set to ch+1. Next, in step 118, it is confirmed whether the channel ch is N+1, where N is the number of channels available for use by the selected AP. If it is N+1, the process proceeds to step 120. If it is not N+1, the process returns to step 114. As described above, in steps 112 to 118, the process of acquiring the number of neighboring APs for each channel available for use by the selected AP is performed.

[0065] Next, in step 120, [S, Index] is created. Here, [S, Index] is an index that ranks the channels so that N_AP is in ascending order, and the elements of this index are channel numbers. That is, in step 120, a process is performed to create an index that ranks the available channels so that the number of neighboring APs is in ascending order.

[0066] Next, in step 122, the first through link-th channels in the index created in step 120 are assigned to the links used by the selected AP, where link is the number of links used by the selected AP.

[0067] As described above, in the standard AAL, first, from available channels, channels with a small number of neighboring APs are selected for the required number of links, and then the selected channels are assigned to all the links to be used.

[0068] 7 is a flowchart showing a process when the channel allocation criterion is the reference OSL according to the first embodiment of the present disclosure. Steps 110 to 120 are the same as the process shown in FIG.

[0069] Next, in step 126, k is set to 1 and l is set to 0. Here, k is a variable indicating the rank in the index created in step 120, and l is a variable indicating the number of links already assigned to the selected AP.

[0070] Next, in step 128, it is checked whether the k-th value in the index created in step 120 is zero. That is, it is checked whether the number of neighbor APs in the corresponding channel of the selected AP is zero. If it is zero, the process proceeds to step 130. If it is not zero, the process proceeds to step 134.

[0071] Next, in step 130, the k-th channel in the index created in step 120 is assigned to the link used by the selected AP, and l is set to l+1. Next, in step 132, it is confirmed whether l is link. As mentioned above, link is the number of links used by the selected AP. If it is link, the process is completed. If it is not link, the process proceeds to step 134.

[0072] In step 134, k is set to k+1. Next, in step 136, it is checked whether k is N+1, where N is the number of channels available to the selected AP, as described above. If it is N+1, proceed to step 138. If it is not N+1, return to step 128.

[0073] Next, in step 138, it is checked whether l is zero, i.e., whether there are no links assigned to the selected AP. If it is zero, the process proceeds to step 140. If it is not zero, the process ends.

[0074] Next, in step 140, the first channel in the index created in step 120 is assigned to the link used by the selected AP, and the process ends. The first channel in the index created in step 120 is the channel with the lowest ranking in the index. That is, in step 140, the channel with the smallest number of corresponding neighboring APs is assigned to the link used by the selected AP.

[0075] As described above, in the standard OSL, if there is a channel with zero neighboring APs, that channel is assigned to the link to be used. If there is no channel with zero neighboring APs, the channel with the fewest neighboring APs is selected and assigned to the link to be used.

[0076] 8 is a flowchart showing a process when the channel allocation criterion is the reference FLN according to the first embodiment of the present disclosure. Steps 110 to 120 are the same as the process shown in FIG.

[0077] Next, in step 142, channels 1 through FLN in the index created in step 120 are assigned to the links used by the selected AP. As mentioned above, FLN is the number of links used by the selected AP, and is a value that can be set freely.

[0078] As described above, in the reference FLN, available channels are first ranked in descending order of the number of neighboring APs. Then, channels with the FLN number are selected in ascending order of the number of neighboring APs, and these channels are assigned to the links to be used.

[0079] [Simulation of communication characteristics according to the first embodiment of the present disclosure] Fig. 9 is a diagram showing an outline of the computer simulation conditions according to the first embodiment of the present disclosure. Fig. 9 shows an example in which five BSSs, 2a to 2e, are arranged in an area of ​​100 m x 100 m. More detailed simulation conditions, including the area and the number of BSSs, are shown in Table 1.

[0080]

[0081] This computer simulation was performed to estimate changes in communication characteristics accompanying the channel allocation process according to the first embodiment of the present disclosure. In particular, changes in average throughput, fairness, and minimum throughput when the LCCS-AAL method and the LCCS-OSL method are used are confirmed.

[0082] In this computer simulation, the median values ​​of data obtained when AP placement was randomly generated 20 times were plotted. As the MCS (Modulation and Coding Scheme), 64QAM 5 / 6 (Quadrature Amplitude Modulation) was used, and 20 MHz transmission was assumed. A proprietary simulator was used.

[0083] 10 is a graph showing the relationship between the number of BSSs and average throughput in a computer simulation according to the first embodiment of the present disclosure. The horizontal axis represents the number of BSSs, and the vertical axis represents the transmission speed. The dashed line represents the results of the LCCS-AAL method, and the solid line represents the results of the LCCS-OSL method.

[0084] 10, it can be seen that the transmission speed with the LCCS-AAL method increases as the number of BSSs increases. In other words, it can be seen that the LCCS-AAL method is superior to the LCCS-OSL method in terms of average throughput.

[0085] 11 is a graph showing the relationship between the number of BSSs and fairness in a simulation according to the first embodiment of the present disclosure. The horizontal axis represents the number of BSSs, and the vertical axis represents the fairness index. The dashed line represents the results of the LCCS-AAL method, and the solid line represents the results of the LCCS-OSL method.

[0086] 11, it can be seen that the fairness index value of the LCCS-OSL method increases as the number of BSSs increases, which means that the LCCS-OSL method is superior to the LCCS-AAL method in terms of fairness.

[0087] 12 is a graph showing the relationship between the number of BSSs and the minimum throughput in a simulation according to the first embodiment of the present disclosure. The horizontal axis represents the number of BSSs, and the vertical axis represents the transmission speed. The dashed line represents the results for the LCCS-AAL method, and the solid line represents the results for the LCCS-OSL method.

[0088] The results in Figure 12 show that although there are areas where the transmission speed is faster with the LCCS-AAL method, the transmission speed with the LCCS-OSL method increases as the number of BSSs increases. In other words, it can be seen that the LCCS-OSL method tends to be superior to the LCCS-AAL method in terms of fairness.

[0089] The results of Figures 10 to 12 show that the LCCS-AAL method is superior in terms of average throughput, while the LCCS-OSL method is superior in terms of fairness and minimum throughput. The LCCS-OSL method uses a channel assignment criterion that selects a channel with no or few APs competing with the selected AP. This reduces the possibility of generating starving APs, and is therefore expected to improve fairness and minimum throughput in dense environments.

[0090] In this computer simulation, we compared the communication quality using the LCCS-AAL method and the LCCS-OSL method, but by also comparing the communication quality using the LCCS-FLN method, it is possible to infer the factors that make the LCCS-FLN method useful.

[0091] As described above, it can be seen that selecting different channel allocation criteria improves different elements of communication characteristics. In other words, by selecting a channel allocation criteria in advance based on which element of communication characteristics the entire system prioritizes, it is possible to prioritize and improve the desired communication characteristics. Therefore, it is also possible to switch the channel allocation criteria depending on the application to be applied, for example.

[0092] 4a, 4a-1, 4a-2, 4b, 4c, 4d, 4e AP 44 Processor 46 Memory 100 Wireless communication system

Claims

1. A wireless communication system having an AP capable of performing wireless communication using multiple links, wherein the AP is configured to perform the following processes: obtain the number of adjacent APs for each available channel; create an index in which the available channels are ranked in ascending order of the number of adjacent APs; check whether the number of adjacent APs of the channels is zero, in ascending order of ranking in the index; if a channel with the number of adjacent APs is zero, assign the channel to the link used by the AP; if there is no channel with the number of adjacent APs is zero and there is no channel assigned to the link used by the AP, assign the channel with the lowest ranking to the link used by the AP; and perform wireless communication using the link to which the channel has been assigned.

2. A wireless communication device capable of performing wireless communication using multiple links, configured to perform the following processes: acquiring the number of adjacent APs for each available channel; creating an index in which the available channels are ranked in ascending order of the number of adjacent APs; checking whether the number of adjacent APs of the channels is zero, in ascending order of ranking in the index; if a channel with the number of adjacent APs being zero exists, assigning the channel to a link used by the wireless communication device; if there is no channel with the number of adjacent APs being zero and there is no channel already assigned to a link used by the wireless communication device, assigning the channel with the lowest ranking to the link used by the wireless communication device; and performing wireless communication using the link to which the channel has been assigned.

3. A wireless communication method implemented by a wireless communication device capable of performing wireless communication using multiple links, comprising: obtaining the number of adjacent APs for each available channel; creating an index in which the available channels are ranked in ascending order of the number of adjacent APs; checking whether the number of adjacent APs of the channels in ascending order of ranking in the index is zero; if a channel with the number of adjacent APs of zero exists, assigning the channel to a link used by the wireless communication device; if there is no channel with the number of adjacent APs of zero and there is no channel assigned to a link used by the wireless communication device, assigning the channel with the lowest ranking to the link used by the wireless communication device; and performing wireless communication using the link to which the channel has been assigned.

4. A wireless communication program capable of performing wireless communication using multiple links and to be performed by a wireless communication device having a processor and a memory, the wireless communication program being stored in the memory and computer-readable, and including a program for causing the processor to perform the following processes: obtaining the number of adjacent APs for each available channel; creating an index in which the available channels are ranked in ascending order of the number of adjacent APs; checking whether the number of adjacent APs of the channels in ascending order of rank in the index is zero; if a channel with the number of adjacent APs being zero exists, assigning the channel to the link being used by the wireless communication device; if there is no channel with the number of adjacent APs being zero and there is no channel assigned to the link being used by the wireless communication device, assigning the channel with the lowest rank to the link being used by the wireless communication device; performing wireless communication using the link to which the channel has been assigned; and performing wireless communication using the link to which the channel has been assigned.

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