Wireless communication system, master wireless station, wireless communication method, and wireless communication program

Abstract

Provided is a wireless communication system in which wireless communication is performed between one master wireless station having a means for performing communication simultaneously using a plurality of links corresponding to a plurality of RF units, and a plurality of slave wireless stations having a means for performing communication simultaneously using a plurality of links corresponding to a plurality of RF units or a means for performing communication using a single link, the master wireless station selecting, under a predetermined restriction, links to be used for the wireless communication between the one master wireless station and the plurality of slave wireless stations individually for the respective slave wireless stations, and performing wireless communication with the slave wireless stations corresponding to the respective selected links using the links individually selected for the respective slave wireless stations.

Description

Wireless communication system, master wireless station, wireless communication method, and wireless communication program

[0001] The present invention relates to a wireless communication system, a master wireless station, a wireless communication method, and a wireless communication program.

[0002] IEEE802.11be is expected to be the next standard for wireless LANs (Local Area Networks). IEEE802.11be will adopt multi-link operation (MLO), which allows communication using multiple links. In multi-link operation, a master wireless station equipped with means for simultaneous communication over multiple links corresponding to multiple RF (Radio Frequency) units communicates with multiple slave wireless stations equipped with means for simultaneous communication over multiple links corresponding to multiple RF units.

[0003] Furthermore, in recent years, for reasons such as improved reliability, wireless communication systems using multiple links have been proposed in wireless LAN systems, including but not limited to Wi-Fi (registered trademark) (Wireless Fidelity).

[0004] However, the IEEE 802.11be standard does not specify a specific link selection method. One possible link selection method is the all-link selection method (conventional method 1), which always uses all available links. Conventional method 1, for example, is a communication method in which traffic is divided equally among all available links.

[0005] In addition to Conventional Method 1, other methods include selecting links while taking into account the airtime occupied by other communications on the link. Examples of such link selection methods include a method of selecting one link from multiple available links that has the smallest airtime occupied by other communications (Conventional Method 2). Another example is a method of dividing traffic in proportion to the airtime occupied by other communications on each link and communicating through that link (Conventional Method 3) (see, for example, Non-Patent Document 1).

[0006] Alvaro Lopez-Raventos, “IEEE 802.11be Multi-Link Operation: When the Best Could Be to Use Only a Single Interface”, 2021 19th Mediterranean Communication and Computer Networking Conference (MedComNet)

[0007] The benefits of link selection include improvements in communication quality, such as throughput, latency, and reliability. In addition, reducing the number of links also reduces the power consumption of the RF parts of unused links, which has the benefit of reducing power consumption.

[0008] In this regard, for example, Conventional Method 1 (all-link selection method) proposed in Non-Patent Document 1 shows poorer performance results than Conventional Methods 2 and 3 (link selection taking airtime into consideration).

[0009] On the other hand, for example, Conventional Methods 2 and 3 proposed in Non-Patent Document 1 realize improvements in communication quality such as throughput, delay time, and reliability by selecting links taking airtime into consideration. That is, Conventional Methods 2 and 3 improve performance by reducing the number of link accesses through link selection. If the number of link accesses can be reduced, the time wasted due to collisions in the CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) mechanism can be reduced, and improved throughput can also be expected.

[0010] However, Conventional Methods 2 and 3 can only be applied when the buffer is not full. When the buffer is full, the airtime congestion level of all links is the same, and the link selection criteria are the same. For this reason, Conventional Methods 2 and 3 have the problem of not being applicable when the buffer is full.

[0011] Therefore, the present disclosure aims to provide a technology that can reduce the number of child wireless stations accessing a link in multi-link operation in which communication is performed using multiple links, and that can select an appropriate link even in the case of a full buffer.

[0012] A wireless communication system according to one embodiment is a wireless communication system in which wireless communication is performed between one parent wireless station having means for simultaneously communicating via multiple links corresponding to multiple RF units, and multiple child wireless stations having means for simultaneously communicating via multiple links corresponding to multiple RF units or means for communicating via a single link, and is characterized in that the parent wireless station selects, for each child wireless station, a link to be used for wireless communication between the parent wireless station and the multiple child wireless stations, subject to predetermined restrictions, and performs wireless communication with the child wireless station corresponding to the selected link using the link individually selected for each child wireless station.

[0013] A master radio station according to one embodiment is a master radio station in a wireless communication system in which wireless communication is performed between one master radio station having means for simultaneously communicating via multiple links corresponding to multiple RF units, and multiple slave radio stations having means for simultaneously communicating via multiple links corresponding to multiple RF units or means for communicating via a single link, and is characterized in that the master radio station selects, after setting a predetermined restriction, a link to be used for wireless communication between the one master radio station and the multiple slave radio stations individually for each slave radio station, and performs wireless communication with the slave radio station corresponding to the selected link using the link individually selected for each slave radio station.

[0014] A wireless communication method according to one embodiment is a wireless communication method in which wireless communication is performed between one parent wireless station having means for simultaneously communicating via multiple links corresponding to multiple RF units, and multiple child wireless stations having means for simultaneously communicating via multiple links corresponding to multiple RF units or means for communicating via a single link, wherein the parent wireless station selects, for each child wireless station, a link to be used for wireless communication between the parent wireless station and the multiple child wireless stations, subject to a predetermined restriction, and performs wireless communication with the child wireless station corresponding to the selected link using the link individually selected for each child wireless station.

[0015] A wireless communication program according to one aspect causes a computer to execute the processing of the wireless communication method described above.

[0016] According to the present disclosure, in multi-link operation in which communication is performed using multiple links, the number of child wireless stations accessing the links can be reduced, and appropriate link selection can be performed even in the case of a full buffer.

[0017] 6 is a diagram showing an example of the configuration of a wireless communication system according to an embodiment. FIG. 7 is a diagram showing an example of the operation (processing) of the wireless communication system shown in FIG. 1. FIG. 8 is a diagram showing the results of a characteristic evaluation performed by a computer simulation simulating CSMA / CA. FIG. 9 is a flowchart showing an example of the procedure of an alternative algorithm. FIG. 10 is a diagram illustrating an example of the processing of the alternative algorithm shown in the flowchart of FIG. 4. FIG. 11 is a diagram showing a fairness index when MCSs are set randomly to multiple child wireless stations. FIG. 12 is a conceptual diagram showing an example of the hardware configuration of a processing circuit included in a control unit of a master wireless station in the embodiments shown in FIGS. 1 to 6.

[0018] Hereinafter, embodiments of a wireless communication system, a master wireless station, a wireless communication method, and a wireless communication program disclosed herein will be described with reference to the drawings. Note that in the following embodiments, a wireless communication system will be described as an example of the wireless communication system, the master wireless station, the wireless communication method, and the wireless communication program disclosed herein.

[0019] <Configuration of an embodiment> FIG. 1 is a diagram showing an example of the configuration of a wireless communication system 1 according to an embodiment.

[0020] 1, the wireless communication system 1 has one master wireless station AP and multiple slave wireless stations STA1 to STAn (where "n" is a positive integer). Note that in the following description and drawings, when it is necessary to distinguish between the multiple slave wireless stations STA1 to STAn, the numbers 1 to n are added after STA, and when it is not necessary to distinguish between them, the numbers 1 to n after STA are omitted.

[0021] In the wireless communication system 1, the master wireless station AP has means for simultaneously communicating via multiple links corresponding to multiple RF units, and the slave wireless stations STA have means for simultaneously communicating via multiple links corresponding to multiple RF units or means for communicating via a single link. In the wireless communication system 1, the master wireless station AP and the multiple slave wireless stations STA1 to STAn can communicate via multi-link operation (MLO). Hereinafter, in this specification and drawings, the general configuration of the master wireless station AP and the slave wireless stations STA will not be described or illustrated.

[0022] The master wireless station AP selects, for each of a plurality of slave wireless stations STA1 to STAn, a link to be used for wireless communication therebetween, subject to a predetermined restriction. The master wireless station AP performs wireless communication with the slave wireless station STA corresponding to the selected link, using the link individually selected for each slave wireless station STA. The master wireless station AP is, for example, an access point. The master wireless station AP includes, for example, an antenna AT, a transceiver unit 10, a packet processing unit 20, a control unit 30, and a storage unit 40.

[0023] The antenna AT receives electromagnetic waves in the air transmitted from the slave wireless station STA and converts them into high-frequency signals. The antenna AT also radiates the high-frequency signals output from the transceiver 10 as electromagnetic waves into the air toward the slave wireless station STA.

[0024] The transceiver 10 includes a plurality of RF units 11. Each of the RF units 11, for example, modulates a baseband signal into a frequency band (RF band) used as a carrier wave during transmission, and demodulates the signal in that frequency band into a baseband signal during reception. The transceiver 10 includes means for simultaneously communicating via a plurality of links corresponding to the plurality of RF units 11.

[0025] The packet processing unit 20 has a packet analysis unit 21 and a packet construction unit 22. The packet analysis unit 21 analyzes a packet acquired from the transmitting / receiving unit 10, for example, performs A / D (Analog to Digital) conversion, and outputs the packet to the control unit 30. The packet construction unit 22 performs D / A (Digital to Analog) conversion on the signal output from the control unit 30 to construct a packet, and outputs the packet to the transmitting / receiving unit 10.

[0026] The control unit 30 has a processor 91 (see FIG. 7 ), which will be described later, such as a CPU (Central Processing Unit) that operates by executing a program. The control unit 30 operates the processor 91 (see FIG. 7 ), which will be described later, by executing a predetermined program stored in a memory 92 (see FIG. 7 ), which will be described later, to comprehensively control the operation of each component of the master wireless station AP. The control unit 30 is connected to each component of the master wireless station AP, for example, via a bus (system bus) (not shown) or the like, so as to enable input and output of various information.

[0027] The control unit 30, for example, executes a predetermined program stored in a memory 92 (described later) to operate a processor 91 (described later) to perform a link selection process (see FIGS. 2 to 6, etc.) (described later).

[0028] The storage unit 40 is a volatile or non-volatile storage medium such as a hard disk drive (HDD), a solid state drive (SSD), a dynamic random access memory (DRAM), or other semiconductor memory. The storage unit 40 is connected to each unit of the master wireless station AP via a bus (system bus, not shown) or the like so as to enable input and output of various types of information, and each unit of the master wireless station AP writes and reads various types of information to and from the storage unit 40.

[0029] The storage unit 40 also stores, for example, information on the link selection process (see FIGS. 2 to 6 , etc.) performed by the control unit 30, which will be described later. The storage unit 40 also stores, for example, various calculation formulas, coefficients, thresholds, calculation results, etc. used in calculations by the various units of the master wireless station AP. The storage unit 40 may be provided outside the master wireless station AP and connected to the master wireless station AP by wire or wirelessly, and may be an external storage medium such as a memory card or a DVD (Digital Versatile Disc), or online storage. The storage unit 40 may also be a memory 92 (see FIG. 7 ), which will be described later.

[0030] In the wireless communication system 1, the master wireless station AP has means for simultaneously communicating via multiple links corresponding to multiple RF units, and the slave wireless stations STA have means for simultaneously communicating via multiple links corresponding to multiple RF units or means for communicating via a single link. In the wireless communication system 1, the master wireless station AP and the multiple slave wireless stations STA1 to STAn can communicate using multi-link operation (MLO).

[0031] Each of the multiple slave wireless stations STA1 to STAn wirelessly communicates with the master wireless station AP using a link selected by the master wireless station AP. The multiple slave wireless stations STA1 to STAn are, for example, terminals (wireless communication terminals). Each of the multiple slave wireless stations STA1 to STAn has, for example, an antenna AT and a transceiver unit 10.

[0032] The antenna AT and the transceiver 10 of the slave wireless station STA are the same as or similar to those in the master wireless station AP, and therefore are denoted by the same reference numerals and detailed description thereof is omitted. Although not shown in the figures, each of the multiple slave wireless stations STA1 to STAn may have, for example, a packet processing unit 20, a control unit 30, and a storage unit 40 that are the same as or similar to those in the master wireless station AP.

[0033] <Operation of an embodiment> Fig. 2 is a diagram showing an example of the operation (processing) of the wireless communication system 1 shown in Fig. 1. Fig. 2 shows an example of the exchange of control signals between a master wireless station AP and a slave wireless station STA.

[0034] The operation (processing) shown in Fig. 2 is initiated when communication is performed by multi-link operation (MLO) between one master wireless station AP and two slave wireless stations STA1 and STA2. The operation (processing) of the master wireless station AP shown in Fig. 2 is performed by a control unit 30 of the master wireless station AP.

[0035] In step S1, the master wireless station AP and the slave wireless stations STA1 and STA2 are connected (associated).

[0036] In step S2, the master wireless station AP requests each of the slave wireless stations STA1 and STA2 to notify them of an MCS (Modulation and Coding Scheme) (modulation method and coding rate index) (STA capability notification request).

[0037] In step S3, the master wireless station AP receives MCS notifications from the slave wireless stations STA1 and STA2 (STA capability notifications).

[0038] In step S4, the master wireless station AP calculates an optimal link for each of the slave wireless stations STA1 and STA2. Specifically, the master wireless station AP calculates an estimated airtime ratio for each of the slave wireless stations STA1 and STA2 from the MCS used by each of the slave wireless stations STA1 and STA2. The master wireless station AP calculates throughput from the calculated estimated airtime ratio for each of the slave wireless stations STA1 and STA2. The master wireless station AP then selects, for each of the slave wireless stations STA1 and STA2, an optimal link to be used for wireless communication between the master wireless station AP and each of the slave wireless stations STA1 and STA2, so that the throughput for each of the slave wireless stations STA1 and STA2 is as fair as possible.

[0039] In step S5, the master wireless station AP notifies each of the slave wireless stations STA1 and STA2 of the one optimum link selected for each of the slave wireless stations STA1 and STA2.

[0040] In step S6, the master station AP enables (ON) each of the slave stations STA1 and STA2 to use only the one optimal link notified for each of the slave stations STA1 and STA2.

[0041] In step S7, the master wireless station AP communicates with each of the slave wireless stations STA1 and STA2 via the optimum link for each of the slave wireless stations STA1 and STA2.

[0042] In step S8, the connection between the master wireless station AP and each slave wireless station STA1 is released (Disassociation).

[0043] In step S9, the master wireless station AP recalculates one optimal link for the slave wireless station STA2. Specifically, the master wireless station AP recalculates one optimal link for the slave wireless station STA2 in the same manner as in step S4. Then, the master wireless station AP selects one optimal link to be used for wireless communication between the master wireless station AP and the slave wireless station STA2.

[0044] In step S10, the master wireless station AP notifies the slave wireless station STA2 of the optimal link reselected for the slave wireless station STA2. Thereafter, the master wireless station AP communicates with the slave wireless station STA2 via the optimal link reselected for the slave wireless station STA2.

[0045] Thereafter, the master wireless station AP and the slave wireless stations STA1, STA2, . . . STAn are connected, and the above processing is carried out every time wireless communication is performed.

[0046] Here, an example of a method for calculating the throughput in step S4 shown in FIG. 2 will be described.

[0047] For example, in a wireless LAN, when multiple n child wireless stations STA1 to STAn access one parent wireless station AP, the airtime ratio of each child wireless station STA in the case of a full buffer is roughly inversely proportional to the transmission speed of the child wireless station STA.

[0048] In this case, the airtime ratio of the slave station STAk is expressed by the following equation (1): ｋ is the airtime ratio of the child wireless station STAk, TS ｋ indicates the transmission rate of the slave station STAk.

[0049]

[0050] The throughput of each slave station STA is calculated by multiplying the airtime ratio by the transmission rate, and is expressed by the following equation (2): ｋ indicates the throughput of the slave station STAk.

[0051]

[0052] As can be seen from the above equations (1) and (2), the throughput of a slave wireless station STA using the same link is the same even if the transmission speeds defined by the MCSs of the slave wireless stations STA are different, because the airtime ratios are different.

[0053] On the other hand, a state in which multiple slave wireless stations STA use one of multiple links is expressed by the following link selection matrix M (Equation (3)). Here, the rows indicate slave wireless station numbers, and the columns indicate link numbers. The matrix expressed by Equation (3) is an example of the link selection matrix M. Equation (3) shows the case where there are three links and seven slave wireless stations.

[0054]

[0055] In the example of equation (3), the link with link number 1 is used by the slave wireless station STA1 with slave wireless station number 1. Similarly, the link with link number 2 is used by the slave wireless stations STA2 and STA3 with slave wireless station numbers 2 and 3. Similarly, the link with link number 3 is used by the slave wireless stations STA4 to STA7 with slave wireless station numbers 4 to 7.

[0056] Here, the throughput of each of the slave stations STA1 to STA7 is expressed by the following equation (4) using a matrix M. Here, TH ｌｉｎｋ１ indicates the throughput of the slave station STA1 using the link with link number 1. Similarly, TH ｌｉｎｋ２ indicates the throughput of the slave wireless stations STA2 and STA3 using the links with link numbers 2 and 3. Similarly, TH ｌｉｎｋ３ indicates the throughput of the slave stations STA4 to STA7 using the link with link number 3.

[0057]

[0058] As explained above, in step S4 of Fig. 2, the master wireless station AP calculates the link selection matrix M based on the above formula, which makes the throughput of each slave wireless station STA fair. This allows link selection to be performed, which has the effect of reducing the number of accesses to the link, and is therefore expected to improve throughput.

[0059] FIG. 3 is a diagram showing the results of a characteristic evaluation performed by a computer simulation that simulates CSMA / CA.

[0060] In Fig. 3, the vertical axis represents throughput, and the horizontal axis represents the number of child wireless stations STAs. The simulation conditions shown in Fig. 3 are 51 child wireless stations, 3 links, all of which have the same bandwidth of 40 MHz, and all of which communicate using MCS6.

[0061] The dotted bar graph in FIG. 3 shows the throughput of each slave wireless station STA when three links are always selected (conventional method 1), and the diagonal line bar graph shows the throughput of each slave wireless station STA when the number of links is limited to one link (method of this embodiment).

[0062] As shown in Fig. 3, the computer simulation results show that the total throughput is 133.4 Mbps for three links and 141.0 Mbps for one link, with an increase rate of 5.6%. That is, the computer simulation results shown in Fig. 3 show that the bars with diagonal lines are larger than the bars with dotted lines, and that the method of this embodiment has a 5.6% increase in total throughput compared to Conventional Method 1.

[0063] Here, an optimization algorithm must be used to find the link selection matrix M. One method is to use simulated annealing, a common numerical method for solving optimization problems. However, even simulated annealing can require a large amount of calculation.

[0064] For this reason, applicant has developed an alternative empirical optimization algorithm (alternative algorithm) that differs from simulated annealing. This alternative algorithm was developed to find the link selection matrix M.

[0065] Fig. 4 is a flowchart showing an example of the procedure of the alternative algorithm. The procedure shown in the flowchart of Fig. 4 is initiated when one master wireless station AP and multiple slave wireless stations STA are communicating by multi-link operation (MLO). The procedure shown in the flowchart of Fig. 4 is performed by the control unit 30 of the master wireless station AP.

[0066] In step S11, the master wireless station AP calculates the number of slave wireless stations to be assigned to each link based on the number of links L and the number of slave wireless stations N. For example, assuming that multiple links have the same bandwidth, the master wireless station AP assigns N / L slave wireless stations to each link. If N / L is not an integer, the master wireless station AP adjusts the number of slave wireless stations to be assigned to each link so that they are roughly even.

[0067] On the other hand, if multiple links have different bandwidths, the master wireless station AP assigns the number of slave wireless stations in proportion to the bandwidth. For example, in the case of three links (bandwidth ratio 1:2:4) and 14 slave wireless stations, the master wireless station AP assigns 2, 4, and 8 slave wireless stations to links 1, 2, and 3, respectively. In this example, the numbers are evenly divisible, but if they are not, the master wireless station AP assigns the number of slave wireless stations so as to maintain this ratio as closely as possible.

[0068] In step S12, the master wireless station AP first determines the number of slave wireless stations belonging to each link through the above preparations, and then randomly assigns slave wireless stations STA to each link. The throughput of the slave wireless stations STA belonging to each link is approximately the same among the slave wireless stations STA belonging to the same link. However, because the MCS of each slave wireless station STA is different, simply randomly assigning the slave wireless stations STA will usually result in different throughputs among the slave wireless stations STA belonging to different links, which is unfair.

[0069] In step S13, the master wireless station AP sequentially exchanges the links assigned to the slave wireless stations STA on a trial basis. As described above, simply randomly assigning slave wireless stations STA to each link does not ensure fairness in the throughput of the slave wireless stations STA belonging to each link. However, by devising a combination of slave wireless stations STA with different MCSs, there is room for adjustment to ensure fairness even among different links. For this reason, the master wireless station AP sequentially exchanges the links assigned to the slave wireless stations STA on a trial basis.

[0070] In step S14, the master wireless station AP determines whether the fairness of the throughput of the slave wireless stations STA belonging to each link has improved since before. If the master wireless station AP determines that the fairness of the throughput of the slave wireless stations STA belonging to each link has improved since before (Yes), the process proceeds to step S15. On the other hand, if the master wireless station AP determines that the fairness of the throughput of the slave wireless stations STA belonging to each link has not improved since before (No), the process proceeds to step S16.

[0071] In step S15, the master wireless station AP maintains the link exchange and performs the same link allocation (after the exchange) because the fairness of the throughput of the replaced slave wireless stations STA has improved compared to before.

[0072] In step S16, the master wireless station AP reverses the link exchange and restores the link allocation before the exchange, since the fairness of the throughput of the replaced slave wireless stations STA is not improved compared to before.

[0073] In step S17, the master wireless station AP determines whether the improvement in fairness of the throughput of the slave wireless stations STA belonging to each link has converged. For example, the master wireless station AP determines that the improvement in fairness has converged if, after trial and successively exchanging the links assigned to the slave wireless stations STA a predetermined number of times, the fairness of the throughput of the slave wireless stations STA belonging to each link has not improved the predetermined number of times in succession.

[0074] When the master wireless station AP determines that the improvement in the fairness of the throughput of the slave wireless stations STA belonging to each link has converged (Yes side), it ends the processing of this flowchart. On the other hand, when the master wireless station AP determines that the improvement in the fairness of the throughput of the slave wireless stations STA belonging to each link has not converged (No side), it returns to the processing of step S13 and repeats the processing of steps S13 to S17 until it determines that the improvement in fairness has converged.

[0075] Fig. 5 is a diagram illustrating an example of the process of the alternative algorithm shown in the flowchart of Fig. 4. Fig. 5 shows an example in which the number of slave wireless stations is 7 and the number of links is 3 (20, 40, and 80 MHz). The dotted cells indicate slave wireless stations STA before replacement, and the shaded cells indicate slave wireless stations STA after replacement.

[0076] First, as shown in the left diagram of Fig. 5, the master wireless station AP divides the seven slave wireless stations into a 1:2:4 ratio in proportion to the bandwidth and randomly assigns them to each link (S11, S12). Next, as shown in the center and right diagrams of Fig. 5, the master wireless station AP exchanges link 1 used by slave wireless station STA3 with link 3 used by slave wireless station STA5 (S13).

[0077] If the performance (fairness) improves as a result of the exchange, the master wireless station AP selects a link after the exchange (S14, S15). On the other hand, if the performance (fairness) does not improve as a result of the exchange, the master wireless station AP returns the link to the state before the exchange (S14, S16). The master wireless station AP repeats the above process until no improvement in performance (fairness) is observed (S17).

[0078] 6 is a diagram showing a fairness index when MCSs are randomly assigned to multiple slave wireless stations STA. In FIG. 6, the vertical axis represents the fairness index, and the horizontal axis represents the number of slave wireless stations. Also, in FIG. 6, the solid line represents the fairness index when the alternative algorithm of this embodiment is used, and the dashed line represents the fairness index when MCSs are randomly assigned to each slave wireless station STA.

[0079] As shown by the dashed line in Fig. 6 , even when an MCS is randomly assigned to each slave wireless station STA, as the number N of slave wireless stations increases, the fairness approaches 1 significantly. On the other hand, when the alternative algorithm of this embodiment is used, the fairness approaches 1 rapidly. In other words, even if there is variation in the MCS of each slave wireless station STA, as the number N of slave wireless stations increases, they converge to the same average value due to the same principle as the central limit theorem. Therefore, according to the alternative algorithm of this embodiment shown in Figs. 4 and 5 , the greater the number N of slave wireless stations, the closer it can get to a quasi-optimal solution.

[0080] <Effects of One Embodiment> As described above, according to the embodiment shown in FIGS. 1 to 6, in multi-link operation in which communication is performed using multiple links, it is possible to reduce the number of child wireless stations accessing links, and to select an appropriate link even in the case of a full buffer.

[0081] 1 to 6, the master wireless station AP selects only one optimal link by taking into consideration the MCSs of the slave wireless stations STAs under its control and the link capacities, thereby reducing the number of link accesses, thereby achieving an increase in total throughput.

[0082] Furthermore, according to the embodiment shown in FIGS. 1 to 6, since only one link is used, power consumption can be reduced compared to when multiple links are used.

[0083] Furthermore, unlike conventional methods 2 and 3, the methods disclosed herein in the embodiments shown in FIGS. 1 to 6 are applicable even in the case of a full buffer.

[0084] Furthermore, according to the embodiment shown in Figures 1 to 6, the alternative link selection algorithms shown in Figures 4 and 5 are used, which makes it possible to reduce the amount of calculations compared to when simulated annealing is used, and therefore it is also possible to reduce power consumption compared to when simulated annealing is used.

[0085] <Hardware Configuration Example> Fig. 7 is a conceptual diagram showing an example of the hardware configuration of the processing circuitry 90 included in the control unit 30 of the master wireless station AP in the embodiment shown in Figs. 1 to 6. The functions described above are realized by the processing circuitry 90. In one aspect, the processing circuitry 90 includes at least one processor 91 and at least one memory 92. In another aspect, the processing circuitry 90 includes at least one dedicated hardware 93.

[0086] When the processing circuit 90 includes a processor 91 and a memory 92, each function is realized by software, firmware, or a combination of software and firmware. At least one of the software and firmware is written as a program. At least one of the software and firmware is stored in the memory 92. The processor 91 realizes each function by reading and executing the program stored in the memory 92.

[0087] When the processing circuitry 90 includes dedicated hardware 93, the processing circuitry 90 may be, for example, a single circuit, multiple circuits, a programmed processor, or a combination thereof. Each function is implemented by the processing circuitry 90.

[0088] The functions of the control unit 30 of the master wireless station AP may be partially or entirely implemented by hardware, or may be implemented as a program executed by a processor. That is, the control unit 30 of the master wireless station AP may be realized by a computer and a program, and the program may be stored in a storage medium or provided via a network.

[0089] 1 to 7, a wireless communication system 1 having one master wireless station AP and multiple STA1 to STAn has been described as an example of one aspect of the present disclosure, but the present disclosure is not limited to this. The form of the system configuration and the like of the present disclosure is not particularly limited.

[0090] 1 to 7, the wireless communication system 1, the master wireless station AP, or the slave wireless station STA has been described as an example of one aspect of the present disclosure, but the present disclosure is not limited to this. The present disclosure can also be realized as a wireless communication method in which processing steps are performed in each part of the wireless communication system 1, the master wireless station AP, or the slave wireless station STA.

[0091] The present disclosure can also be realized as a wireless communication program that causes a computer to execute processing steps in each part of the wireless communication system 1, the master wireless station AP, or the slave wireless station STA.

[0092] The present disclosure can also be realized as a storage medium (non-transitory computer-readable storage medium) on which a wireless communication program is stored. The wireless communication program can be stored and distributed on removable media such as a CD (Compact Disc), a DVD (Digital Versatile Disc), or a USB (Universal Serial Bus) memory. The wireless communication program may be uploaded to a network via a network interface (not shown) of the master wireless station AP or the slave wireless station STA, or may be downloaded from the network and stored in a memory 92 or the like.

[0093] The features and advantages of the embodiments will be apparent from the above detailed description. It is intended that the claims encompass the features and advantages of the above-described embodiments without departing from the spirit and scope of the claims. Furthermore, any improvements and modifications will be readily apparent to those skilled in the art. Therefore, it is not intended that the scope of the inventive embodiments be limited to the above-described embodiments, and appropriate improvements and equivalents within the scope of the disclosed embodiments may be utilized.

[0094] 1...wireless communication system; 1 to 3...links (link numbers); 1 to 7...child wireless stations (child wireless station numbers); 10...transmitter / receiver; 11...RF unit; 20...packet processing unit; 21...packet analysis unit; 22...packet construction unit; 30...control unit; 40...storage unit; 90...processing circuit; 91...processor; 92...memory; 93...hardware; AP...parent wireless station; AT...antenna; L...number of links; M...link selection matrix (matrix); N...number of child wireless stations; STA, STA1 to STAn, STAk...child wireless stations

Claims

1. A wireless communication system in which wireless communication is performed between one parent wireless station having means for simultaneously communicating via multiple links corresponding to multiple RF units, and multiple child wireless stations having means for simultaneously communicating via multiple links corresponding to multiple RF units, or means for communicating via a single link, wherein the parent wireless station selects, subject to predetermined restrictions, the link to be used for the wireless communication between the parent wireless station and the multiple child wireless stations, individually for each child wireless station, and performs the wireless communication with the child wireless station corresponding to the selected link, using the link individually selected for each child wireless station.

2. A wireless communication system according to claim 1, characterized in that the master wireless station limits the number of links to one, and selects the link to be used for the wireless communication between one master wireless station and multiple slave wireless stations individually for each slave wireless station.

3. A wireless communication system according to claim 2, wherein the parent wireless station calculates an expected airtime ratio for each child wireless station from the MCS (modulation scheme / coding rate index) of each child wireless station using each link to calculate throughput, and selects the link to be used for the wireless communication between one parent wireless station and multiple child wireless stations for each child wireless station so that the throughput for each child wireless station is as fair as possible.

4. A wireless communication system as claimed in claim 3, characterized in that the parent wireless station first determines the number of child wireless stations belonging to each link in proportion to the bandwidth of each link, and randomly assigns the child wireless stations to each link, sequentially exchanges the links used among the multiple child wireless stations, and when the link exchange makes the throughput fair, the parent wireless station maintains the link exchange, while when the throughput does not become fair, the parent wireless station restores the original link, thereby repeating the link exchange until the throughput becomes fair, thereby individually selecting, for each child wireless station, the link to be used for the wireless communication between one parent wireless station and multiple child wireless stations so that the throughput of each child wireless station becomes as fair as possible.

5. A master radio station in a wireless communication system in which wireless communication is performed between a master radio station having means for simultaneously communicating over multiple links corresponding to multiple RF units, and multiple slave radio stations having means for simultaneously communicating over multiple links corresponding to multiple RF units or means for communicating over a single link, wherein the master radio station selects, after setting predetermined restrictions, the link used for the wireless communication between the master radio station and the multiple slave radio stations individually for each of the slave radio stations, and performs the wireless communication with the slave radio station corresponding to the selected link using the link individually selected for each of the slave radio stations.

6. A wireless communication method in which wireless communication is performed between one parent wireless station having means for simultaneously communicating via multiple links corresponding to multiple RF units, and multiple child wireless stations having means for simultaneously communicating via multiple links corresponding to multiple RF units or means for communicating via a single link, wherein the parent wireless station selects, for each child wireless station, the link to be used for the wireless communication between the parent wireless station and the multiple child wireless stations, subject to specified restrictions, and performs the wireless communication with the child wireless station corresponding to the selected link, using the link individually selected for each child wireless station.

7. A wireless communication program for causing a computer to execute the processing of the wireless communication method according to claim 6.