Communication device and communication method

Abstract

The present disclosure relates to a communication device and a communication method. This communication device controls at least one AP and at least one repeater placed under the control of any one of the APs. The communication device is configured to execute: a first process for setting one or more parameters including a channel that can be allocated to the AP or the repeater; a second process for calculating a utility function for each of the parameters; a third process for selecting an optimal parameter on the basis of the result of the calculation; and a process for repeating the first process, the second process, and the third process for each of the at least one AP and the at least one repeater. The first process performed on each repeater is for setting the repeater to the same channel as a channel set for the AP that is a subordinate source of the repeater.

Description

Communication device and communication method

[0001] The present disclosure relates to a communication device and a communication method.

[0002] There is a technique for optimizing the throughput of an entire system by optimizing parameters such as a frequency channel and a bandwidth to be used for a plurality of base stations (APs) included in the system.

[0003] Optimization of the parameters can be realized, for example, by defining an evaluation value based on the frequency channel and the bandwidth used by each AP and selecting a parameter that can maximize the minimum value or the total of the evaluation values. As an example of this method, RATOP (Resource allocation based on Area Throughput Optimization Policy) is known (see, for example, Non-Patent Document 1).

[0004] In RATOP, a centralized control device grasps the state of mutual interference between APs and allocates radio resources such as a frequency channel and a bandwidth to be used by each AP. Also, in RATOP, as an evaluation value, a utility function that is a satisfaction degree of an expected throughput with respect to a required traffic volume is defined.

[0005] The centralized control device performs control, for example, so as to maximize the total value of the utility function. When the system has a configuration including repeaters, the centralized control device optimizes the parameters used by each repeater in addition to each AP. In this case, the centralized control device has allocated different frequency channels and bandwidths to different APs or repeaters.

[0006] BAHirantha Sithira Abeysekera et al., "Network Controlled Frequency Channel and Bandwidth Allocation Scheme for IEEE 802.11a / n / ac Wireless LANs: RATOP", 2014 IEEE 25th International Symposium on Personal, Indoor and Mobile Radio Communications, pp.1041-1045

[0007] However, the method described above does not account for cases where a repeater wants to use the same frequency channel for both the uplink and downlink. In other words, the central control unit had the problem of not being able to allocate the same frequency channel and bandwidth to different access points or repeaters.

[0008] The primary objective of this disclosure is to provide a communication device that can allocate the same frequency channel and bandwidth to different APs or repeaters in order to solve the aforementioned problems.

[0009] Furthermore, a second objective of this disclosure is to provide a communication device that can allocate the same frequency channel and bandwidth to different APs or relay devices.

[0010] A first aspect of this disclosure is a communication device for controlling at least one AP and at least one relay station under either of the APs, configured to perform a first process of setting one or more parameters including a channel that can be assigned to the AP or relay station; a second process of calculating a utility function for each of the parameters; a third process of selecting the optimal parameters based on the calculation results; and a process of repeating the first, second, and third processes for each of the at least one AP and at least one relay station, wherein the first process for the relay station is preferably a process of setting the same channel for the relay station as the channel set for the AP to which the relay station belongs.

[0011] A second aspect of this disclosure is a communication method to be implemented by a communication device that controls at least one AP and at least one relay unit located under any of the APs, comprising: setting one or more parameters including channels that can be assigned to the AP or relay unit; calculating a utility function for each of the parameters; selecting the optimal parameter based on the calculation results; and repeating the setting, calculation, and selection for each of the at least one AP and at least one relay unit, wherein the setting for the relay unit is preferably the same channel set for the relay unit as the channel set for the AP to which the relay unit belongs.

[0012] According to the first and second aspects of this disclosure, the same frequency channel and bandwidth can be assigned to different APs or repeaters.

[0013] This figure shows an example configuration of a wireless communication system according to Embodiment 1 of this disclosure. This figure shows the hardware configuration of a centralized control device according to Embodiment 1 of this disclosure. This figure shows the allocation of wireless resources according to Embodiment 1 of this disclosure. This flowchart shows the processing performed by the centralized control device according to Embodiment 1 of this disclosure. This figure shows the RATOP algorithm executed by the centralized control device according to Embodiment 1 of this disclosure. This figure shows an example configuration of a wireless communication system according to a comparative example. This figure shows the allocation of wireless resources according to Embodiment 2 of this disclosure. This figure shows an example configuration of a wireless communication system according to Embodiment 3 of this disclosure. This figure shows an example configuration of a wireless communication system according to Embodiment 4 of this disclosure.

[0014] Embodiment 1 Figure 1 is a diagram showing an example configuration of a wireless communication system according to Embodiment 1 of the present disclosure. The wireless communication system 100 includes a central control device 10. The central control device 10 is a communication device that grasps the state of mutual interference of each wireless communication device and allocates wireless resources such as frequency channels and bandwidth to be used by each wireless communication device. This allocation is performed in a manner that maximizes the overall throughput of the wireless communication system 100.

[0015] The wireless communication system 100 also includes an AP20. The AP20 is a communication device connected to the network 8. In this embodiment, the AP20 is connected to the central control unit 10 via the network 8. The network 8 may be a wired network or a wireless network.

[0016] Furthermore, AP20 is a communication device that can have relay devices under its control. In this embodiment, AP20 has a relay device 22 under its control.

[0017] The repeater 22 is a wireless communication device capable of communicating on both the uplink and downlink sides, and is not connected to the network 8. The repeater 22 in this embodiment is a repeater that uses a common frequency channel for both the uplink and downlink sides. The repeater 22 shares the same frequency channel for both the uplink and downlink sides by switching the wireless communication between the uplink and downlink sides, for example, by time division multiplexing.

[0018] Furthermore, the repeater 22 is a wireless device that can have other repeaters or terminals under its control. In this embodiment, the repeater 22 has a terminal 24 under its control.

[0019] AP20, repeater22, and terminal24 all use the same frequency channel, ch1, for wireless communication. Hereafter, the AP, repeater, and terminal included in the system under consideration may be collectively referred to as wireless equipment.

[0020] The wireless communication system 100 also includes an AP40. The AP40 performs wireless communication using channel 2, which is a different frequency channel from channel 1.

[0021] Here, the dashed arrows indicate wireless devices that allocate wireless resources to each other. In this embodiment, the central control unit 10 allocates wireless resources by determining which channel 1 is used by AP20, the repeater 22, and the terminal 24, and which channel 2 is used by AP40.

[0022] Figure 2 shows the hardware configuration of a centralized control device according to Embodiment 1 of the present disclosure. Each function of the centralized control device 10 may be partially or entirely configured by hardware such as a PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array), or it may be configured as a program executed by a processor such as a CPU.

[0023] For example, the centralized control device 10 can be implemented using a computer and a program, and the program can be recorded on a storage medium or provided via a network.

[0024] As shown in Figure 2, the centralized control unit 10 has an input unit 108, an output unit 101, a communication unit 102, a CPU 103, a memory 104, and an HDD 105 connected via a bus 106, and functions as a computer. The centralized control unit 10 is also capable of inputting and outputting data to and from a computer-readable storage medium 107.

[0025] The input unit 108 is, for example, a keyboard and mouse. The output unit 101 is, for example, a display device such as a display.

[0026] The communication unit 102 is, for example, a communication interface that communicates with a wireless device to be controlled.

[0027] The CPU 103 controls each component of the central control unit 10 and performs predetermined processing. The memory 104 and HDD 105 store data, etc.

[0028] The storage medium 107 is capable of storing programs and the like that cause the central control unit 10 to execute its functions. Note that the architecture of the central control unit 10 is not limited to the example shown in Figure 2.

[0029] Figure 3 shows the allocation of wireless resources according to Embodiment 1 of the present disclosure. In this embodiment, the central control device 10 allocates resources to AP20, repeater 22, and AP40. At this time, the central control device 10 assigns the same frequency channel and bandwidth to AP20 and repeater 22. As a result, resources are allocated equally to AP20 and AP40.

[0030] Figure 4 is a flowchart showing the processing performed by the centralized control device according to Embodiment 1 of this disclosure. First, in step 100, the centralized control device 10 determines whether it is an information collection trigger. If it is an information collection trigger, the process proceeds to step 102. If it is not an information collection trigger, the process proceeds to step 104.

[0031] In step 102, the centralized control unit 10 collects information.

[0032] Next, in step 104, the central control unit 10 determines whether it is a calculation trigger. If it is a calculation trigger, the process proceeds to step 106. If it is not a calculation trigger, the process returns to step 100.

[0033] In step 106, the central control unit 10 performs calculations and proceeds to step 108. Details of the calculations will be described later.

[0034] Next, in step 108, the central control unit 10 determines whether it is a parameter setting trigger. Parameters are, for example, the channel or bandwidth to be assigned to each wireless device. If it is a parameter setting trigger, the system proceeds to step 110. If it is not a parameter setting trigger, step 108 is repeated.

[0035] In step 110, the central control unit 10 performs parameter setting. That is, it sets the optimal parameters selected based on the calculation results performed in step 106 to the corresponding wireless device.

[0036] Figure 5 shows the RATOP algorithm executed by the centralized control device according to Embodiment 1 of this disclosure. This algorithm corresponds to the details of the calculation performed by the centralized control device 10 in step 108 of the flowchart shown in Figure 4.

[0037] Before explaining the RATOP algorithm, we will first explain the utility function. The wireless communication system 100 according to this embodiment has a plurality of wireless devices connected to the network 8. The central control unit 10 controls RATOP for the plurality of wireless devices. In this case, the evaluation value used as an indicator of control is assumed to be the utility function U (corresponding to satisfaction) shown in equation 1.

[0038] a: AP and relay device identifier b: Bandwidth c: Channel (primary channel) R: Data rate (MCS)

[0039] Hereafter, APs and repeaters with identifier 'a' will be collectively referred to as AP(a). The transmittable traffic of AP(a) is AP(a)'s estimated throughput, which depends on the channel usage status of other APs and repeaters. The estimated throughput of each AP and repeater is derived from the positional relationship between APs and repeaters using the same frequency channel. This positional relationship is estimated, for example, using RSSI. For example, if APs and repeaters in interfering positions use the same frequency channel, it can be estimated that throughput will decrease.

[0040] Furthermore, the amount of traffic to be accommodated (which depends on the amount of data generated) is, for example, the estimated maximum traffic of AP(a) shown in Equation 2.

[0041]

[0042] At this time, we assume that the maximum traffic estimate is the traffic capacity per terminal multiplied by the number of assumed terminals. The central control unit 10 then performs a process to maximize the sum ΣU of the utility functions U according to the following algorithm.

[0043] RATOP Algorithm: (A): The centralized control device 10 "temporarily assigns" the used channel bandwidth of each AP according to a predetermined rule. (B): The centralized control device 10 calculates the sum ΣU of the utility functions U of each AP in the case of (A) above. (C): The centralized control device 10 reassigns the channel bandwidth to the AP with a low utility function U and controls it so that ΣU does not decrease. Then, the centralized control device 10 repeats the above (C) within the range of predetermined conditions.

[0044] Referring to FIG. 5, the RATOP algorithm will be described. As shown in FIG. 5, the centralized control device 10 performs the processes of Phase I (initial calculation) and Phase II (optimization).

[0045] In Phase I, the centralized control device 10 selects one AP or relay device and designates it as AP-a (S200), sets the bandwidth b that can be assigned to AP-a (S202), sets the channel (primary channel) c that can be assigned to AP-a (S204), and calculates the utility function U of AP-a (S206).

[0046] However, in Steps 202 and 204, when the relay device is placed under a specific AP, restrictions are imposed on the setting of the bandwidth b and the channel c. Specifically, first, the bandwidth b and the channel c are assigned to a specific AP, and subsequently, the same bandwidth b and channel c as those of the AP that is the source of subordination are assigned to the subordinate relay device. For example, in the wireless communication system 100, first, the bandwidth b and the channel c are assigned to AP20, and subsequently, the same bandwidth b and channel c are assigned to the relay device 22.

[0047] Then, the centralized control device 10 executes the processes of S204 and S206 for all channels c, and further repeats the process for all bandwidths b. That is, the centralized control device 10 calculates the utility function U for each combination of the bandwidth b and the channel c that can be assigned to the selected AP and relay device. In the following embodiments, the combination of the bandwidth and the channel will be described, but the process may be performed not only for this combination but also for the combination of set values including the channel.

[0048] Next, the central control unit 10 selects a combination of (b, c) based on the utility function U (S208) and repeats the process for all APs and relay devices. Specifically, if there are multiple options for the combination of (b, c) that satisfy certain conditions for the utility function U, it checks if there is a combination of (b, c) currently in use among them. If there is a combination of (b, c) currently in use, that combination is given priority.

[0049] The certain condition that the utility function U satisfies is either that it reaches its maximum value, or that the difference between the utility function U at its maximum value and the current utility function U is below a certain threshold.

[0050] Furthermore, if there are APs and relays that have been continuously used for a certain period of time or longer for which the utility function U satisfies certain conditions for (b, c), those APs and relays may be excluded from the targets for control. This exclusion process can reduce the time and resources required to determine (b, c).

[0051] In Phase II, the central control unit 10 optimizes the utility function U (S210). For example, the central control unit 10 selects the AP or repeater with the smallest utility function U, and calculates the utility function for each of the (b, c) combinations that can be assigned to the selected AP or repeater, provided that the degradation of the sum ΣU of the utility functions U is within a certain range. Note that the certain range may include cases where the degradation is negative, i.e., an improvement. Then, based on the calculated utility functions, the central control unit selects a (b, c) combination and repeats the process for all APs and repeaters.

[0052] However, in step 210, the central control unit 10 restricts the setting of bandwidth b and channel c if the repeater is under the control of a specific AP. Specifically, the central control unit 10 first allocates bandwidth b and channel c to the specific AP, and then allocates the same bandwidth b and channel c to the subordinate repeater as to the source AP. For example, in the wireless communication system 100, the central control unit 10 first allocates bandwidth b and channel c to AP 20, and then allocates the same bandwidth b and channel c to repeater 22.

[0053] Here, the central control unit 10 prioritizes selecting the AP or repeater with the smallest utility function U. In particular, if the number of repeaters under an AP is greater than or equal to a certain value, prioritizing the AP in the above selection allows for the allocation of wireless resources to the subordinate repeaters to be determined collectively, thereby reducing the computational load and computation time. The specific value may be, for example, a value that causes the computational load or computation time performed by the central control unit 10 to be greater than or equal to a threshold.

[0054] Prioritizing selection may be achieved, for example, by replacing the utility function U related to the relevant AP or relay device with a utility function U', which is a function obtained by multiplying utility function U by a coefficient. The utility function U' is shown in equation 3.

[0055] a: AP identifier b: Bandwidth c: Channel (Primary Channel) R: Data Rate (MCS) A: Coefficient

[0056] Note that this coefficient A is greater than 1 if AP(a) is an AP, and 1 if AP(a) is a repeater. In other words, if AP(a) is an AP, the AP can be selected preferentially by making the value of the utility function U' larger.

[0057] The central control unit 10 then determines the bandwidth and channel after allocation for each AP and relay unit's selected combination of (b, c) (S212).

[0058] Figure 6 shows an example configuration of a wireless communication system according to a comparative example. Referring to Figure 6, the advantages obtained by the RATOP algorithm according to this disclosure will be explained.

[0059] The comparative example wireless communication system 100a includes a central control device 10a. The central control device 10a grasps the state of mutual interference among wireless devices and allocates wireless resources such as frequency channels and bandwidth to be used by each wireless device. This allocation is performed in a manner that maximizes the overall throughput of the wireless communication system 100.

[0060] The wireless communication system 100a also includes an AP 20. The AP 20 has a repeater 26 under its control. The repeater 26 is a repeater that uses different frequency channels for the uplink and downlink. The repeater 26 also has a terminal 28 under its control.

[0061] AP20 and repeater26 communicate wirelessly using channel ch1. Repeater26 and terminal28 communicate wirelessly using channel 3, which is a different frequency channel from ch1.

[0062] The wireless communication system 100a also includes an AP40. The AP40 performs wireless communication using channel 2, which is a different frequency channel from channels 1 and 3.

[0063] Here again, the dashed arrows indicate wireless devices that allocate wireless resources to each other. In this embodiment, the central control unit 10a allocates wireless resources by determining which channel 1 is used by AP20 and repeater 26, which is used by AP40, and which is used by repeater 26 and terminal 28.

[0064] The central control unit 10a assigns different frequency channels and bandwidths to different APs or repeaters. However, the central control unit 10 does not anticipate the case where the repeater 26 wants to use a common frequency channel for both the uplink and downlink. In other words, the central control unit 10a had the problem of not being able to assign the same frequency channel and bandwidth to different APs or repeaters.

[0065] In this embodiment, the central control device 10 restricts the selection of bandwidth b and channel c in the RATOP algorithm. Specifically, it first assigns bandwidth b and channel c to a specific AP, and then assigns the same bandwidth b and channel c to its subordinate repeaters. As a result, the same frequency channel and bandwidth can be assigned to different APs or repeaters.

[0066] Embodiment 2 Figure 7 is a diagram showing the allocation of wireless resources according to Embodiment 2 of the present disclosure. The central control device 10 according to this embodiment differs from Embodiment 1 in that it allocates different bandwidths when allocating the same frequency channel to the uplink and downlink sides of the repeater 22.

[0067] The central control device 10 according to this embodiment allocates wireless resources according to the RATOP algorithm shown in Figure 5. However, in steps 202, 204, and 210, the central control device 10 restricts the settings of bandwidth b and channel c if the repeater is under the control of a specific AP.

[0068] Specifically, the central control unit 10 first allocates bandwidth b and channel c to a specific AP. Subsequently, the central control unit 10 allocates the same channel c as the source AP to its subordinate relay devices, but allocates a different bandwidth b' to them. The different bandwidth b' is, for example, a bandwidth narrower than bandwidth b. Alternatively, the different bandwidth b' may be a bandwidth wider than bandwidth b.

[0069] For example, in a wireless communication system 100, the central control unit 10 first assigns AP 20 a bandwidth of 80 MHz and channel ch1. Subsequently, the central control unit 10 assigns the same channel ch1 to repeater 22, but assigns a different bandwidth of 40 MHz to it.

[0070] This embodiment offers advantages when there are wireless devices that interfere with the terminal 28. For example, consider a case in a wireless communication system 100 where wireless devices not under the control of the central control unit 10 interfere with the terminal 28. In this case, even if a bandwidth of 80 MHz is allocated to the repeater 22, 40 MHz of wireless communication with the terminal 28 may interfere with wireless devices not under the control of the central control unit 10.

[0071] In this case, the central control device 10 according to this embodiment changes the bandwidth allocated to the repeater 22 from 80 MHz to 40 MHz. This change is obtained as a result of the central control device 10 executing the RATOP algorithm. As a result, the terminal 28 can avoid interference with wireless devices that are not under the control of the central control device 10.

[0072] As described above, the centralized control device according to this embodiment can assign the same frequency channel and bandwidth to different APs or relay devices. Furthermore, the centralized control device according to this embodiment can prevent interference between its subordinate wireless devices and wireless devices that are not under its control.

[0073] Embodiment 3 Figure 8 is a diagram showing an example of the configuration of a wireless communication system according to Embodiment 3 of the present disclosure. The central control device 10 according to this embodiment differs from Embodiments 1 and 2 in that it calculates the amount of traffic accommodated by each AP and relay device in the calculation of the utility function U based on the terminals under its control.

[0074] The wireless communication system 100b according to this embodiment includes a central control unit 10. The central control unit 10 is connected to AP20 via a network 8.

[0075] AP20 has repeaters 22a, repeaters 22b, and terminal 24a under its control. Repeater 22a has terminals 24b and 24c under its control. Repeater 22b also has terminal 24d under its control.

[0076] AP20, repeaters 22a and 22b, and terminals 24a, 24b, 24c and 24d perform wireless communication using channel ch1.

[0077] The central control device 10 according to this embodiment allocates wireless resources according to the RATOP algorithm shown in Figure 5. However, the central control device 10 calculates the amount of traffic accommodated by each AP and relay in the calculation of the utility function U based on the terminals under its control.

[0078] Specifically, the central control unit 10 calculates the traffic capacity of each AP and relay unit based on a value obtained by multiplying the number of terminals under its control by the traffic capacity per terminal. For example, in the wireless communication system 100b, the central control unit 10 calculates the traffic capacity of AP 20 based on a value obtained by multiplying the number of terminals under its control (4) by the traffic capacity per terminal. Similarly, the central control unit 10 calculates the traffic capacity of relay unit 22a based on a value obtained by multiplying the number of terminals under its control (2) by the traffic capacity per terminal.

[0079] The configuration of this embodiment offers advantages as the number of terminals under the control of each AP and relay increases. The wireless resources required by each AP and relay increase as the number of terminals under their control increases. Therefore, the central control device 10 calculates the amount of traffic each AP and relay can handle in the calculation of the utility function U based on the terminals under its control. As a result, each AP and relay can secure the wireless resources necessary for wireless communication with the terminals under its control.

[0080] As described above, the central control device according to this embodiment can allocate the same frequency channel and bandwidth to different APs or relay devices. Furthermore, the central control device according to this embodiment can secure the radio resources necessary for each AP and relay device to communicate with the terminals under its control.

[0081] Embodiment 4 Figure 9 is a diagram showing an example of the configuration of a wireless communication system according to Embodiment 4 of the present disclosure. The central control device 10 according to this embodiment differs from Embodiments 1 to 3 in that it allocates wireless resources based on the parameter conditions used by each relay device under its control.

[0082] The wireless communication system 100c according to this embodiment includes a central control unit 10. The central control unit 10 is connected to APs 20a, 20b, 20c, and 20d via a network 8.

[0083] AP20a has a repeater 26a under its control. Repeater 26a is a repeater that uses different frequency channels for the uplink and downlink. Repeater 26a also has a terminal 28a under its control.

[0084] AP20b has a repeater 22a under its control. Repeater 22a is a repeater that uses a common frequency channel for both the uplink and downlink. Repeater 22a also has a terminal 24a under its control.

[0085] AP20c has a repeater 22b under its control. Repeater 22b is a repeater that uses a common frequency channel for both the uplink and downlink. Repeater 22b also has a terminal 24b under its control.

[0086] AP20d has a repeater 26b under its control. Repeater 26b is a repeater that uses different frequency channels for the uplink and downlink. Repeater 26b also has a terminal 28b under its control.

[0087] The central control device 10 according to this embodiment allocates wireless resources according to the RATOP algorithm shown in Figure 5. However, prior to calculating the utility function U, the central control device 10 obtains parameter conditions for each repeater. Parameter conditions are the parameter conditions set by each repeater for the wireless resources used on the uplink and downlink sides, such as the channel and bandwidth settings. Then, the central control device 10 calculates the utility function based on the parameter conditions obtained for each repeater.

[0088] Specifically, the central control unit 10 first acquires parameter conditions for each relay unit. For example, in the wireless communication system 100c, the central control unit 10 acquires parameter conditions for relay units 20a to 20d. This acquisition may be done via each of the APs 20a to 20d under its control, or it may be acquired directly from each of the relay units 20a to 20d.

[0089] Next, the central control unit 10 calculates a utility function based on the acquired parameter conditions. For example, suppose the parameter condition for the repeater 26a is "use different frequency channels for the uplink and downlink sides". The central control unit 10 first assigns channel ch1 to AP20a. Subsequently, the central control unit 10 assigns a different channel ch2 to repeater 26a.

[0090] For example, suppose the parameter condition for repeater 22a is "use the same bandwidth and a common frequency channel for both the uplink and downlink." The central control unit 10 first assigns a bandwidth of 80 MHz and channel ch1 to AP20b. Subsequently, the central control unit 10 assigns the same bandwidth of 80 MHz and a common channel ch1 to repeater 22a.

[0091] For example, suppose the parameter condition for repeater 22b is "use different bandwidths and a common frequency channel for the uplink and downlink." The central control unit 10 first assigns AP20c a bandwidth of 80 MHz and channel ch1. Then, the central control unit 10 assigns repeater 22b a different bandwidth of 40 MHz and a common channel ch1.

[0092] For example, suppose the parameter conditions for repeater 26b are "use different frequency channels for the uplink and downlink sides" and "the frequency channels used for the uplink and downlink sides are spaced at least a certain value apart." The central control unit 10 first assigns channel ch1 to AP20d. Then, the central control unit 10 assigns channel ch3 to repeater 26b, which is different from channel 1 and is spaced at least a certain value apart from channel 1.

[0093] Furthermore, if the parameter condition is set to "However, the frequency channels used for the uplink and downlink should be spaced apart by a certain value or more," interference between the uplink and downlink wireless communications of the corresponding repeater can be avoided. Therefore, it is preferable that the specific value is one that allows the wireless communications to avoid interference with each other.

[0094] This embodiment assumes a case where the parameter conditions of multiple relays in a wireless communication system are not common. The central control unit 10 acquires the parameter conditions for each relay under its control in advance and allocates wireless resources based on the acquired parameter conditions. As a result, each relay can perform wireless communication using wireless resources that match the parameter conditions.

[0095] As described above, the central control device according to this embodiment can allocate wireless resources that match the parameter conditions of each relay device to each relay device. In other words, the central control device according to this embodiment can realize the distribution of wireless resources according to embodiments 1 to 3 in any combination.

[0096] The possible forms of disclosure are listed below as supplementary information.

[0097] [Note 1] A communication device that communicates with an AP and a relay station located under the AP, and assigns parameters to the AP and the relay station, wherein the communication device always assigns to the relay station the same parameters as those set for the AP to which the relay station belongs. [Note 2] The communication device according to Note 1, wherein the process of assigning the parameters to the AP and the relay station includes a calculation process, the calculation process includes a process of selecting an AP or relay station with a low evaluation value of the parameters, and the selection is performed by prioritizing the AP over the relay station. [Note 3] The communication device according to any one of Notes 1 to 3, wherein the parameters are a combination of channel and bandwidth or channel only. [Note 4] The communication device according to any one of Notes 1 to 4, wherein the AP or the relay station has terminals under its control, the reference value in the calculation of the evaluation value is the amount of traffic accommodated at the AP and the relay station, and the amount of traffic accommodated is calculated based on the number of terminals of the target AP or relay station. [Note 5] The process of assigning the parameters to the AP and the repeater includes the process of obtaining the respective parameter conditions of the AP and the repeater, wherein the repeater is a communication device according to any one of Notes 1 to 5, having different parameter conditions for the uplink and downlink sides.

[0098] 20a Repeater 22 Repeater 22a Repeater 22b Repeater 24 Terminal 24a Terminal 24b Terminal 24c Terminal 24d Terminal 26 Repeater 26a Repeater 26b Repeater 28 Terminal 28a Terminal 28b Terminal

Claims

1. A communication device for controlling at least one AP and at least one relay unit under any of the APs, configured to perform: a first process of setting one or more parameters including a channel that can be assigned to the AP or the relay unit; a second process of calculating a utility function for each of the parameters; a third process of selecting the optimal parameters based on the results of the calculation; and a process of repeating the first process, the second process and the third process for each of the at least one AP and the at least one relay unit, wherein the first process for the relay unit is a process of setting the same channel for the relay unit as the channel set for the AP to which the relay unit belongs.

2. The communication device according to claim 1, wherein the parameter further includes an assignable bandwidth, the first process includes a process of setting the bandwidth for the AP, and the first process for the repeater is a process of setting a bandwidth for the repeater that is different from the bandwidth set for the AP to which the repeater belongs.

3. The communication device according to claim 1, wherein the AP or relay has terminals under its control, the utility function is calculated based on the amount of traffic handled by the AP or relay, and the amount of traffic handled is calculated based on the number of terminals of the terminal multiplied by the amount of traffic per terminal.

4. A communication method to be implemented by a communication device that controls at least one AP and at least one relay unit located under any of the APs, comprising: setting one or more parameters including channels that can be assigned to the AP or the relay unit; calculating a utility function for each of the parameters; selecting the optimal parameter based on the result of the calculation; and repeating the setting, calculation and selection for each of the at least one AP and the at least one relay unit, wherein the setting for the relay unit is to set the same channel for the relay unit as the channel set for the AP to which the relay unit belongs.

Images