Wireless LAN base station device and wireless LAN terminal device

Abstract

This invention relates to a wireless LAN base station apparatus and a wireless LAN terminal apparatus. A predetermined STA includes: a terminal information collection unit that collects terminal information from itself and other STAs, the terminal information being used to select STAs for simultaneous transmission and control simultaneous transmission; and a simultaneous transmission request unit that, based on the terminal information, determines the generation of QoS data frames and sends a request frame for simultaneous transmission to an AP. The AP includes: the terminal information collection unit; a simultaneous transmission determination unit that, by receiving the request frame, selects a combination of STAs for simultaneous transmission based on the terminal information; and a trigger transmission unit that instructs the STAs for simultaneous transmission to transmit simultaneously and sends a trigger frame containing information required to control simultaneous transmission. The STA specified by the trigger frame is configured to simultaneously transmit wireless frames to the AP.

Description

[0001] This application is a divisional application based on the invention with application number 201680011983.6, application date February 23, 2016, applicant Nippon Telegraph and Telephone Corporation, entitled "Wireless Communication System, Wireless Communication Method, Wireless LAN Base Station Device and Wireless LAN Terminal Device". Technical Field

[0002] This invention relates to a wireless communication system, a wireless communication method, a wireless LAN base station device, and a wireless LAN terminal device that allow multiple wireless LAN terminal devices to simultaneously transmit wireless frames to a single wireless LAN base station device. In this specification, the wireless LAN terminal device is abbreviated as STA, and the wireless LAN base station device is abbreviated as AP. Background Technology

[0003] In the IEEE 802.11ac wireless LAN standard, MU-MIMO (Multi-user Multiple Input Multiple Output) is used to improve downlink communication efficiency from AP to STA. MU-MIMO enables simultaneous transmission of radio frames from one AP to multiple STAs. Furthermore, to further improve the efficiency of simultaneous transmission, a technique for effective flow pairing is proposed, which compares the characteristics of the traffic.

[0004] Non-Patent Document 1 specifies a process for simultaneous transmission of downlink MU-MIMO, or the exchange of radio frames between the AP and STAs at that time. It also specifies a process for grouping STAs destined for radio frames transmitted via MU-MIMO and simultaneously transmitting them after attaching a Group ID. In contrast, Non-Patent Document 2 illustrates a grouping method for implementing efficient downlink MU-MIMO based on downlink traffic characteristics that can be collected by the AP.

[0005] On the other hand, to improve the efficiency of uplink communication from STA to AP, simultaneous transmission in the uplink direction of multiple STAs has been studied. Simultaneous transmission of wireless frames from multiple STAs to one AP can be achieved through multiplexing using space, frequency, or the areas of both parties; however, as shown in Non-Patent Document 3, this method has not yet been established in wireless LAN systems. Non-Patent Document 4 proposes a process in which the AP transmits wireless frames containing information such as resource processes before multiple STAs begin simultaneous transmission, thus triggering the simultaneous transmission.

[0006] Prior art literature

[0007] Non-patent literature

[0008] Non-patent document 1: IEEE 802.11ac, "Wireless LAN Medium Access Control (MAC) and Physical (PHY) Layer Specifications", December 2013

[0009] Non-patent literature 2: Y.Inoue, S.Shinohara, M.Mizoguchi, and M.Morikura, "Flow-Based User Pairing Scheme for Muti-User Transmissions over WLANs," Proceedings of the 11th IEEE Vehicular Technology Society Asia Pacific Wireless Communications Symposium (APWCS), Ping Tung, Aug. 28-29, 2014.

[0010] Non-patent literature 3: O. Aboul-Magd, “802.11 HEW SG Proposed PAR,” doc.: IEEE 802.11-14 / 0165r1, March 2014

[0011] Non-Patent Literature 4: Jinyoung Chun, Wookbong Lee, “Uplink multi-user transmission”, 11-13 / 1388r0, LG Electronics Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] As illustrated in reference 4, even with simultaneous uplink transmissions using a triggering radio frame sent by the AP, there is no guarantee that the combination of STAs transmitting simultaneously will necessarily achieve effective transmission. For example, when multiple STAs transmit simultaneously, it is foreseeable that the communication quality of each STA will deteriorate compared to the case where each STA transmits individually. Therefore, STAs transmitting simultaneously expect the characteristic degradation caused by radio frame propagation to be sufficiently small. However, since there is no means to select the combination of STAs, it may be more efficient for each STA to transmit individually compared to multiple STAs transmitting simultaneously.

[0014] The purpose of this invention is to provide a wireless communication system, a wireless communication method, a wireless LAN base station device, and a wireless LAN terminal device, which, when multiple STAs simultaneously transmit wireless frames to an AP via a multiplexed connection, can select the STAs to transmit to simultaneously and perform simultaneous transmission on that STA.

[0015] means for solving problems

[0016] According to a first invention, a wireless communication system is provided, wherein an AP is connected to multiple STAs, and wireless frames are simultaneously transmitted from the multiple STAs to the AP via a multiplexing connection. The AP includes: a terminal information collection unit, which collects terminal information from the multiple STAs, the terminal information being used to select STAs for simultaneous transmission and control simultaneous transmission; a simultaneous transmission determination unit, which selects a combination of STAs for simultaneous transmission based on the terminal information; and a trigger transmission unit, which sends a trigger frame to the STAs for simultaneous transmission, the trigger frame indicating simultaneous transmission and containing information required to control simultaneous transmission, wherein the STAs specified by the trigger frame are configured to simultaneously transmit wireless frames to the AP.

[0017] According to a second invention, a wireless communication system is provided, wherein an AP is connected to multiple STAs, and wireless frames are simultaneously transmitted from the multiple STAs to the AP via a multiplexing connection. A predetermined STA among the multiple STAs includes: a terminal information collection unit, which collects terminal information from itself and other STAs, the terminal information being used to select STAs for simultaneous transmission and control simultaneous transmission; and a simultaneous transmission request unit, which, based on the terminal information, determines the generation of QoS (Quality of Service) data frames and sends a request frame requesting simultaneous transmission to the AP. The AP includes: a terminal information collection unit, which collects terminal information from the multiple STAs, the terminal information being used to select STAs for simultaneous transmission and control simultaneous transmission; a simultaneous transmission determination unit, which, by receiving the request frame sent from the predetermined STAs, selects a combination of STAs for simultaneous transmission based on the terminal information; and a trigger transmission unit, which sends a trigger frame to the STAs for simultaneous transmission, the trigger frame indicating simultaneous transmission and containing information required to control simultaneous transmission, the STA specified by the trigger frame being configured to simultaneously transmit wireless frames to the AP.

[0018] In the wireless communication system of the first or second invention, the AP includes an access control unit. When performing separate CSMA / CA control for each of a wireless frame destined for a STA and a trigger frame destined for multiple STAs to be transmitted simultaneously, the access control unit sets the parameters of the CSMA / CA control that make it easier for the side with more frames or more data to obtain access rights, and sends a wireless frame or trigger frame that obtains access rights through the separate CSMA / CA control.

[0019] In the wireless communication system of the first or second invention, the AP includes an access control unit. When performing general CSMA / CA control for each of a radio frame destined for a STA and a trigger frame destined for multiple STAs to be transmitted simultaneously, the access control unit selects the radio frame or trigger frame with the larger number of frames or data volume to be transmitted, and obtains access rights to transmit through the general CSMA / CA control.

[0020] According to a third invention, a wireless communication method is provided, wherein an AP is connected to multiple STAs, and wireless frames are simultaneously transmitted from the multiple STAs to the AP via a multiplexing connection. The AP has the following steps: Step 1, collecting terminal information from the multiple STAs, the terminal information being used to select STAs for simultaneous transmission and control simultaneous transmission; Step 2, selecting a combination of STAs for simultaneous transmission based on the terminal information; and Step 3, sending a trigger frame to the STAs for simultaneous transmission, the trigger frame indicating simultaneous transmission and containing information required to control simultaneous transmission, and the STAs specified by the trigger frame simultaneously transmitting wireless frames to the AP.

[0021] According to a fourth invention, a wireless communication method is provided, wherein an AP is connected to multiple STAs, and wireless frames are simultaneously transmitted from the multiple STAs to the AP via a multiplexing connection. A predetermined STA among the multiple STAs has the following steps: Step 1, collecting terminal information from itself and other STAs, the terminal information being used to select STAs for simultaneous transmission and control simultaneous transmission; and Step 2, determining the generation of QoS data frames based on the terminal information and sending a request frame requesting simultaneous transmission to the AP. The AP has the following steps: Step 1, collecting terminal information from the multiple STAs, the terminal information being used to select STAs for simultaneous transmission and control simultaneous transmission; Step 2, selecting a combination of STAs for simultaneous transmission based on the terminal information by receiving the request frame sent from the predetermined STAs; and Step 3, sending a trigger frame to the STAs for simultaneous transmission, the trigger frame indicating simultaneous transmission and containing information required to control simultaneous transmission, and the STA specified by the trigger frame simultaneously transmitting wireless frames to the AP.

[0022] In the wireless communication method of the third or fourth invention, when performing separate CSMA / CA control for each of the wireless frames destined for a STA and the trigger frames destined for multiple STAs to be transmitted simultaneously, the AP sets the CSMA / CA control parameters that make it easier for the side with more frames or more data to obtain access rights, and sends the wireless frame or trigger frame that obtains access rights through the separate CSMA / CA control.

[0023] In the wireless communication method of the third or fourth invention, when a general CSMA / CA control is performed for each of the wireless frames destined for a STA and the trigger frames destined for multiple STAs to be transmitted simultaneously, the AP selects the wireless frame or trigger frame with the larger number of frames or data volume to be transmitted, and obtains access rights through the general CSMA / CA control to transmit.

[0024] According to a fifth invention, an access point (AP) for a wireless communication system is provided. In the wireless communication system, one AP is connected to multiple STAs, and wireless frames are simultaneously transmitted from the multiple STAs to the AP via a multiplexing connection. The AP includes: a terminal information collection unit, which collects terminal information from the multiple STAs, the terminal information being used to select STAs for simultaneous transmission and control simultaneous transmission; a simultaneous transmission determination unit, which selects a combination of STAs for simultaneous transmission based on the terminal information; and a trigger transmission unit, which sends a trigger frame to the STAs for simultaneous transmission, the trigger frame indicating simultaneous transmission and containing information required to control simultaneous transmission.

[0025] In the AP of the fifth invention, an access control unit is included. When performing separate CSMA / CA control for each of the radio frames destined for STAs and the trigger frames destined for multiple STAs to be transmitted simultaneously, the access control unit sets the parameters of the CSMA / CA control that make it easier for the side with more frames or more data to obtain access rights, and sends the radio frame or trigger frame that obtains access rights through the separate CSMA / CA control.

[0026] In the AP of the fifth invention, there is an access control unit. When performing general CSMA / CA control for each of the radio frames destined for STAs and the trigger frames destined for multiple STAs to be transmitted simultaneously, the access control unit selects the radio frame or trigger frame with the larger number of frames or data volume to be transmitted, and obtains access rights to transmit through the general CSMA / CA control.

[0027] According to the sixth invention, a STA is provided for a wireless communication system. In the wireless communication system, an AP is connected to multiple STAs, and wireless frames are simultaneously transmitted from multiple STAs to the AP through a multiplexing connection. The STA includes: a terminal information collection unit, which collects terminal information from itself and other STAs, and the terminal information is used to select STAs for simultaneous transmission and control simultaneous transmission; and a simultaneous transmission request unit, which determines the generation of QoS data frames based on the terminal information and sends a request frame for simultaneous transmission to the AP.

[0028] Invention Effects

[0029] In this invention, multiple STAs selected for simultaneous transmission are triggered by the generation of QoS data frames and notified via trigger frames, enabling them to begin simultaneous transmission at appropriate timings using a multiplexing method. Furthermore, by selecting a combination of STAs with good data transmission efficiency for simultaneous transmission, this invention improves the throughput of simultaneous transmission. Attached Figure Description

[0030] Figure 1 This is a diagram illustrating a configuration example of the wireless communication system of the present invention.

[0031] Figure 2 This is a diagram illustrating an example of the configuration of the AP and STA in the wireless communication system of the present invention;

[0032] Figure 3 This is a diagram illustrating the control sequence of Embodiment 1 in the wireless communication system of the present invention;

[0033] Figure 4 This is a diagram illustrating the control sequence of Embodiment 2 in the wireless communication system of the present invention;

[0034] Figure 5 This is a diagram illustrating the control sequence of Embodiment 3 in the wireless communication system of the present invention;

[0035] Figure 6 This is a diagram illustrating the control sequence of Embodiment 4 in the wireless communication system of the present invention;

[0036] Figure 7 This is a flowchart illustrating the simultaneous transmission control process of the AP in Embodiment 1 of the wireless communication system of the present invention;

[0037] Figure 8 This is a flowchart illustrating the simultaneous transmission control process of the AP in Embodiment 2 of the wireless communication system of the present invention;

[0038] Figure 9 This is a flowchart illustrating the simultaneous transmission control process of STA and AP in Embodiment 3 of the wireless communication system of the present invention;

[0039] Figure 10 This is a flowchart illustrating the simultaneous transmission control process of STA and AP in Embodiment 4 of the wireless communication system of the present invention;

[0040] Figure 11 This is a diagram showing a configuration example 1 of the access control unit 15;

[0041] Figure 12 This is a diagram showing a configuration example 2 of the access control unit 15. Detailed Implementation

[0042] Figure 1 An example configuration of the wireless communication system of the present invention is shown.

[0043] exist Figure 1 In the diagram, one access point (AP) is connected to multiple STA1 to STAn. Solid lines indicate the ability to send and receive radio frames between the AP and STA1 to STAn. Dashed lines indicate that STA1 can receive radio frames sent by STA2 and STA3.

[0044] Figure 2 An example configuration of AP and STA in the wireless communication system of the present invention is shown.

[0045] exist Figure 2 In this configuration, the AP and STA include: a wireless communication unit 11, which performs wireless frame transmission and reception and multiplexing processing during simultaneous transmission; a control unit 12, which performs overall control, including wireless frame transmission and reception control; an information management unit 13, which manages the information required for each control function; a simultaneous transmission determination unit 14, which collects terminal information from each STA, determines the selection of combinations of STAs transmitting simultaneously and the efficiency of data transmission during simultaneous transmission, and generates trigger frames to notify the STAs transmitting simultaneously of the information required for simultaneous transmission control; and an access control unit 15, which obtains access rights to wireless frames through CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) control. Here, the wireless frames include downlink data frames transmitted by the AP, uplink data frames transmitted by the STAs, terminal information used to control simultaneous transmission by the STAs, notification frames, request frames, trigger frames, and other control signals.

[0046] The following is for reference Figures 3-6 The control sequence of Examples 1-4 shown is as follows: Figures 7-10 The simultaneous transmission control process shown in Examples 1 to 4 will be explained for each example.

[0047] (Example 1)

[0048] Figure 3 The control sequence of Embodiment 1 in the wireless communication system of the present invention is shown.

[0049] Figure 7 Steps S11 to S15 of the simultaneous transmission control process, which is an embodiment 1 of the wireless communication system of the present invention, are shown.

[0050] In step S11, the AP collects and aggregates the terminal information required for simultaneous transmission from STA1 to STAn, including the selected STAs transmitting simultaneously. The terminal information includes propagation characteristics such as traffic information, received power from each STA, and channel status.

[0051] Traffic information for each STA can include, for example, the presence, quantity, and bit size of high-priority access type transmission packets; whether packets exceeding a threshold exist in the transmission queue; the application category of the transmission packets; information related to the generation rate of user data generated in the STA; the frequency of user data generation; and whether periodically generated transmission packets exist. By including information about the packet length or bit size of uplink data frames in the terminal information, the STA can determine the NAV period length when the AP sets the NAV (Network Allocation Vector) during packet transmission prohibition periods. Furthermore, by predicting the generation of uplink traffic based on the application category of downlink traffic transmitted from the AP, this can be used in selecting combinations of STAs transmitting simultaneously. For example, in the case of applications such as VoIP (Voice over IP), when transmission packets are periodically generated in the downlink, it can be anticipated that the same transmission packets will be generated in the uplink. Moreover, the AP can collect statistics on the uplink traffic of STAs over a period of time to predict whether periodically generated uplink traffic exists and use this information in selecting STAs transmitting simultaneously.

[0052] Furthermore, when multiple STAs transmit simultaneously, the communication quality of each STA is expected to deteriorate compared to the case of a single STA transmitting. Therefore, it is desirable to combine STAs whose characteristics are minimally degraded due to the propagation of radio frames during simultaneous transmission. To determine this propagation characteristic, the predicted received power value of the frames transmitted by the STA is compared with the propagation channel quality between the AP and the characteristics among multiple STAs. Terminal information regarding whether there are STAs with equal received power values ​​during simultaneous transmission can also be used in the simultaneous transmission determination.

[0053] Here, the methods for collecting terminal information can include: periodically or proactively sending frames containing terminal information from each STA; responding sequentially to AP polling; carrying terminal information in uplink data frames from each STA; or carrying terminal information in ACK frames as acknowledgments to downlink data frames. When uplink data frames contain terminal information, the AP can continuously perform simultaneous communication for multiple users based on this invention by including terminal information in data frames simultaneously sent by multiple users in the uplink direction. Alternatively, information within the QoS control field specified in IEEE 802.11e can be used to understand the generation of QoS data frames in the STA. Furthermore, terminal information can be collected in the background using networks other than wireless LANs, such as mobile networks or wired networks. For example, IEEE 802.11k or other information exchange sequences can be used.

[0054] Alternatively, terminal information from all STAs may not be collected at the AP; instead, terminal information may be transmitted to the AP only by STAs with uplink traffic. Furthermore, in cases where a predetermined STA collects terminal information from other STAs as described in embodiments 3 and 4 below, it is also possible for a predetermined STA to collect terminal information only from audible STAs.

[0055] Next, in steps S12 and S13, the AP selects a combination of STAs to transmit simultaneously based on the collected terminal information, calculates the data transmission efficiency when the STAs in this combination transmit simultaneously, and determines whether it is good or bad. The calculation of data transmission efficiency first selects a combination of STAs with high similarity based on factors such as data rate, and calculates the data transmission efficiency of simultaneous transmission based on this combination of STAs. The data rate is determined by factors such as the frame size of the uplink traffic generated by each STA, the packet generation interval, the access type of the transmitted packets, propagation characteristics, and the transmission capacity of each STA. Then, the data transmission efficiency of simultaneous transmission by the selected combination of STAs is compared with the data transmission efficiency when each STA transmits individually. If the former value is higher, the simultaneous transmission efficiency is determined to be better. Alternatively, the data transmission efficiency of simultaneous transmission by the selected combination of STAs can be compared with a predetermined threshold to determine the quality of the simultaneous transmission efficiency.

[0056] As a result, if the simultaneous data transmission efficiency is poor, the AP will not perform simultaneous transmission control on the uplink in step S14. On the other hand, if the simultaneous data transmission efficiency is determined to be good, in step S15, the AP generates a trigger frame (TRG) to indicate simultaneous uplink transmission for the selected simultaneous transmission STAs, and sends the trigger frame after obtaining access rights through carrier sense via CSMA / CA control.

[0057] In addition, the following processing can also be performed in the access acquisition process in step S15: sending and receiving RTS (Request to send) / CTS (Clear to send) frames in CSMA / CA control, assuming that the selected STA completes the time for simultaneous transmission and setting NAV to prohibit other STAs from sending, etc.

[0058] The trigger frame sent by the AP that has obtained access rights includes the combination of STAs that will transmit simultaneously, selected using terminal information collected to determine simultaneous transmission, information on the wireless communication resources available to each STA, frequency, and information required for timing adjustments. Furthermore, the trigger frame may also include, for example, information on the demodulation method for simultaneous transmission and penalty information for reducing the coding rate.

[0059] The trigger frame sent by the AP received the simultaneously sent instruction from the STA, for example, Figure 3 The STA1 to STAn shown are transmitted simultaneously based on the specified information using any one of the following methods or a combination thereof: Frequency Division Multiple Access (FDMA), Space Division Multiple Access (SDMA, MU-MIMO), other multiplexing methods.

[0060] However, the AP transmits the downlink data frames to the STA after gaining access based on CSMA / CA control. Therefore, regarding the CSMA / CA control used for transmitting downlink data frames and the CSMA / CA control used for transmitting trigger frames indicating simultaneous transmission of uplink data frames, in... Figure 2 The access control unit 15 of the AP shown needs to be adjusted.

[0061] Here, if priority control corresponding to the access type is applied to downlink data frames, it is possible to consider configuring priority control corresponding to the access type of simultaneously transmitted uplink data frames in the trigger frame as well. Such priority control corresponding to the access type is performed by setting the parameters of the CSMA / CA control.

[0062] In EDCA (Enhanced Distributed Channel Access), which extends CSMA / CA control, the AIFS (Advanced Access Window) time corresponding to the access type (AC) is used instead of the DIFS (Distributed Access Window) time used to determine if the channel is idle. For example, the higher the priority of the access type, the shorter the AIFS time. The minimum CWmin and maximum CWmax of the Contention Window (CW), which determines the random backoff value for collision prevention, are also set according to the access type. For example, the higher the priority of the access type, the smaller the CWmin and CWmax values ​​are. Furthermore, TXOP (Transmission Opportunity) is also set according to the access type. TXOP is a parameter representing the exclusive channel usage period after obtaining channel access rights. For example, the higher the priority of the access type, the larger the TXOP value, and the more frames can be transmitted after obtaining access rights.

[0063] When prioritizing access types by adjusting EDCA parameters such as AIFS, CWmin, CWmax, and TXOP, priority control between downlink data frames and trigger frames is required for each access type. For example, in Configuration Example 1, where downlink data frames and trigger frames are controlled separately for each access type using CSMA / CA, EDCA parameters are set for each access type to determine which side has a larger number of frames to be sent or a larger amount of data, making it easier for them to gain access. (Refer to the following...) Figure 11 Please provide a detailed explanation.

[0064] Furthermore, in Configuration Example 2, where general CSMA / CA control is applied to downlink data frames and trigger frames for each access type, a selection unit is set up for each access type to select the side with more frames to be transmitted or more data volume for CSMA / CA control. See below for reference... Figure 12 Please provide a detailed explanation.

[0065] Figure 11 Example 1 of the configuration of the access control unit 15 is shown.

[0066] exist Figure 11 In the process, the uplink / downlink transmission management function unit 100 inputs downlink data frames from the AP and trigger frames for instructing simultaneous uplink transmission. For each access type, it calculates the number of frames or the amount of data, inputs the downlink data frames to the downlink data frame access control unit 20, and inputs the trigger frames to the trigger frame access control unit 30.

[0067] The downlink data frame access control unit 20 is configured as shown in IEEE 802.11e, including a downlink data frame access type mapping unit 21, transmission queues 22-1 to 22-4 corresponding to the access type, CSMA / CA control units 23-1 to 23-4, and an anti-collision processing unit 24. The downlink data frame access type mapping unit 21 inserts downlink data frames into the transmission queues 22-1 to 22-4 corresponding to the access type. For downlink data frames waiting in each transmission queue, the CSMA / CA control units 23-1 to 23-4 perform access control based on the priority of the EDCA parameters corresponding to the access type.

[0068] The trigger frame access control unit 30 has the same configuration as the downlink data frame access control unit 20, including a trigger frame access type mapping unit 31, transmission queues 32-1 to 32-4 corresponding to the access type, CSMA / CA control units 33-1 to 33-4 corresponding to the access type, and an anti-collision processing unit 24. The trigger frame access type mapping unit 31 inserts trigger frames into transmission queues 32-1 to 32-4 corresponding to the access type. For trigger frames waiting in each transmission queue, the CSMA / CA control units 33-1 to 33-4 perform access control based on the priority of the EDCA parameters corresponding to the access type.

[0069] In the CSMA / CA control units 23-i and 33-i corresponding to access type i, the default values ​​of the EDCA parameters corresponding to access type i can also be set together. If they are the same access type i, for example, the default values ​​of the EDCA parameters can be weighted to give priority to access control of the trigger frame. Here, i is 1 to 4.

[0070] Furthermore, the uplink / downlink transmission management function unit 100 adjusts the EDCA parameters of the side with more frames or more data waiting to be transmitted in the transmission queues 22-i and 32-i, based on the total number of downlink data frames and trigger frames for each access type. This adjustment is made easier for the side with more frames or more data waiting to be transmitted in the transmission queues 22-i and 32-i to obtain access rights.

[0071] The anti-collision processing unit 24 is the same in the downlink data frame access control unit 20 and the trigger frame access control unit 30. When the transmission timing overlaps in the access control of each access type, the anti-collision processing unit 24 executes the access control of the one with higher priority. However, between downlink data frames and trigger frames of the same access type, for example, the access control of the trigger frame may be executed first.

[0072] Figure 12 Example 2 of the configuration of the access control unit 15 is shown.

[0073] exist Figure 12 In this example, configuration example 2 is a configuration example obtained by sharing the CSMA / CA control units 23-1 to 23-4 of the downlink data frame access control unit 20 and the CSMA / CA control units 33-1 to 33-4 of the trigger frame access control unit 30 in configuration example 1.

[0074] The uplink / downlink transmission management function unit 100 inputs downlink data frames from the AP and trigger frames for instructing simultaneous uplink transmission. It calculates the number of frames or data volume for each access type, inputs downlink data frames to the downlink data frame access type mapping unit 21, and inputs trigger frames to the trigger frame access type mapping unit 31.

[0075] Downlink data frames are inserted into transmission queues 22-1 to 22-4 corresponding to the access type by the access type mapping unit 21. Trigger frames are inserted into transmission queues 32-1 to 32-4 corresponding to the access type by the access type mapping unit 31. For downlink data frames waiting in transmission queue 22-i of access type i and trigger frames waiting in transmission queue 32-i, the selection unit 41-i selects one of them, and the CSMA / CA control unit 23-i performs access control based on the priority of the EDCA parameters corresponding to access type i.

[0076] The uplink / downlink transmission management function unit 100, based on the total number of downlink data frames and trigger frames for each access type, causes the access type i selection unit 41-i to select the option with more frames or data waiting to be transmitted in the transmission queues 22-i and 32-i, and causes the CSMA / CA control unit 23-i to perform access control. In configuration example 1, since the EDCA parameters of the CSMA / CA control units 23-i and 33-i are adjusted, the probability of selecting downlink data frames and trigger frames depends on the statistical probability that the random backoff values ​​are the same. However, in configuration example 2, one of them is determined based on the number of frames or data to be transmitted.

[0077] When timing overlap occurs due to access control for each access type, the anti-collision processing unit 41 executes the access control of the one with higher priority. Furthermore, timing overlap due to access control may involve trigger frames and downlink data frames of different access types, or trigger frames of different access types or downlink data frames of different access types.

[0078] As described above, in the access control unit 15 of the AP, if a trigger frame is sent for simultaneously sending downlink data frames destined for STAs or uplink data frames destined for multiple STAs, transmission is performed after obtaining access rights based on CSMA / CA control. On the other hand, if an STA sends an uplink data frame, transmission is also performed after obtaining access rights based on CSMA / CA control. Here, for example, if there are multiple STAs requesting transmission for an AP, performing CSMA / CA control separately significantly reduces the probability of the AP obtaining access rights. In contrast, simultaneous transmission of uplink data frames by multiple STAs eliminates the transmission requests of each STA, making it easier for the AP to obtain access rights, but this is only possible when trigger frames can be transmitted efficiently.

[0079] exist Figure 11In Configuration Example 1, when the default values ​​of the EDCA parameters corresponding to each access type are weighted in a manner that prioritizes access control of trigger frames, the EDCA parameters can be adjusted according to the number of STAs requesting transmission. For example, when bidirectional traffic occurs, the CW size in the AP is set to be less than the default value, or the CW size is set to be greater than the default value for STAs that can connect to the AP or transmit simultaneously using beacon frames or frames on other wireless or wired networks. This allows APs that perform carrier sensing to transmit trigger frames for simultaneous transmission to begin transmitting first.

[0080] (Example 2)

[0081] Figure 4 The control sequence of Embodiment 2 in the wireless communication system of the present invention is shown.

[0082] Figure 8 Steps S21 to S29 of the simultaneous transmission control process are shown as Embodiment 2 of the wireless communication system of the present invention.

[0083] In step S21, the AP collects and sums the terminal information required for simultaneous transmission control of the STAs selected from STA1 to STAn. Next, in steps S22 and S23, the AP selects a combination of STAs for simultaneous transmission based on the collected terminal information, calculates the data transmission efficiency of this combination of STAs transmitting simultaneously, and determines whether it is good or bad. Here, if the data transmission efficiency of simultaneous transmission is not determined to be good, the AP performs a process in step S24 that does not perform simultaneous transmission control in the uplink. The above processing is similar to... Figure 7 The steps S11 to S14 of Example 1 shown are the same.

[0084] The feature of this embodiment is that when the data transmission efficiency of simultaneous transmission is determined to be good in step S23, the AP enables the STA to obtain access rights when sending a trigger frame to the STA that is transmitting simultaneously to indicate that the uplink is transmitting simultaneously.

[0085] Here, when the AP determines that the data transmission efficiency of simultaneous transmission is good, in step S25, it sends a notification frame indicating that simultaneous transmission is possible to the STAs transmitting simultaneously. The STAs that have obtained access rights through carrier sense and random backoff control among those receiving the notification frame send a request frame to the AP. Figure 4In the example, STA1 sends a request frame. After receiving the request frame from the STA that has obtained access rights in step S26, the AP, in steps S27 and S28, reselects a combination of STAs that will send simultaneously based on the terminal information previously collected by the AP, recalculates the data transmission efficiency of this combination of STAs sending simultaneously, and determines whether it is good or bad. At this time, if the terminal information has been updated, there may be a combination of STAs that is different from the combination of STAs selected in step S22. In addition, the STA that has obtained access rights and sent the request frame is in an idle state, so it can also be determined as one of the STAs sending simultaneously.

[0086] As a result, when the data transmission efficiency of simultaneous transmission is not determined to be good, the AP does not perform simultaneous transmission control in the uplink in step S24. On the other hand, when the data transmission efficiency of simultaneous transmission is determined to be good again, in step S29, the AP generates and sends a trigger frame for the selected STAs transmitting simultaneously to indicate simultaneous transmission in the uplink.

[0087] If the STA that receives the notification frame acquires access and sends a request frame, and the AP that receives the request frame wants to send a trigger frame after the SIFS time, then the STA can reliably send the frame using its acquired access, and simultaneous transmission can begin. Furthermore, if we assume the time from when the AP receives the request frame and sends the trigger frame until the corresponding STA completes simultaneous transmission, and set NAVs for other STAs not selected for simultaneous transmission based on the request frame sent by the STA or other received / transmitted RTS / CTS frames, then the STA selected based on the AP's trigger frame can reliably perform simultaneous transmission.

[0088] (Example 3)

[0089] Figure 5 The control sequence of Embodiment 3 in the wireless communication system of the present invention is shown.

[0090] Figure 9 The steps S30 to S33 and S34 to S39 of the simultaneous transmission control process in Embodiment 3 of the wireless communication system of the present invention are shown. Steps S30 to S33 are the processing of the STA, and steps S34 to S39 are the processing of the AP.

[0091] Examples 1 and 2 describe the process by which the AP collects and aggregates terminal information from each STA and selects a combination of STAs to send data simultaneously. However, Example 3 is characterized by the following: a predetermined STAx collects its own information and that of other terminals, aggregates the information, and determines whether simultaneous transmission is possible, notifying the AP accordingly. The AP then selects a combination of STAs to send data simultaneously based on this notification. For example, in... Figure 1In the STA1 shown, it is assumed that the uplink frames of STA2 and STA3 are heard, and their traffic information is collected as terminal information. Alternatively, STA1 can also collect terminal information from other STA2 to STAn using the AP method described in Example 1. However, it is assumed that the AP also collects terminal information from STA1 to STAn independently, just as in Example 1.

[0092] In step S30, the pre-defined STAx collects and aggregates the information of the STAs selected for simultaneous transmission and the terminal information required for controlling simultaneous transmission. Next, in steps S31 and S32, STAx selects a combination of STAs for simultaneous transmission based on its own and other terminal information, calculates the data transmission efficiency of this combination of STAs transmitting simultaneously, and determines whether it is good or bad. If the data transmission efficiency of simultaneous transmission is not determined to be good, it returns to step S31 to collect terminal information again. On the other hand, if the data transmission efficiency of simultaneous transmission is determined to be good, in step S33, STAx sends a request frame indicating that simultaneous transmission is possible to the AP. The request frame may also contain combination information of the STAs performing simultaneous transmission or their terminal information, a request for access rights to the AP, and a request from multiple users in the uplink direction to simultaneously transmit data including its own STA. Additionally, STAx may also send a request frame to the AP when it is aware of the generation of QoS data frames of itself and other STAs.

[0093] On the other hand, in step S34, the AP collects and aggregates information from STA1 to STAn to select STAs that will transmit simultaneously and the terminal information required for controlling simultaneous transmission. After receiving a request frame from the STA in step S35, the AP selects a combination of STAs that will transmit simultaneously based on the previously collected terminal information in steps S36 and S37, calculates the data transmission efficiency of the STAs in this combination when transmitting simultaneously, and determines whether it is good or bad. At this time, if the request frame sent by the STA contains the combination information of the STAs that will transmit simultaneously as determined by the STA or its terminal information, it can also be combined with the terminal information collected by the AP for the process of selecting a combination of STAs that will transmit simultaneously. In addition, if the terminal information has been updated, there may be cases where a combination of STAs that is different from the combination of STAs selected in step S31 is selected.

[0094] As a result, when the data transmission efficiency of simultaneous transmission is not determined to be good, the AP does not perform simultaneous transmission control in the uplink in step S38. On the other hand, when the data transmission efficiency of simultaneous transmission is determined to be good, in step S39, for the selected STAs transmitting simultaneously, a trigger frame is generated to indicate simultaneous transmission in the uplink, and the trigger frame is transmitted after obtaining access rights through carrier sense and random backoff control.

[0095] If steps S30 to S33 in the STA are removed, then steps S34 to S39 in the AP are basically the same as steps S11 to S15 in Embodiment 1. In this embodiment, after determining whether simultaneous transmission is possible based on the terminal information collected by the predetermined STAx, the terminal information collected by the AP, or the combination information of the STAs to be transmitted simultaneously determined by STAx, or their terminal information, is used to finally select the combination of STAs to be transmitted simultaneously, thereby reducing the processing burden in the AP.

[0096] (Example 4)

[0097] Figure 6 The control sequence of Embodiment 4 in the wireless communication system of the present invention is shown.

[0098] Figure 10 The simultaneous transmission control process steps S40-S43 and S44-S49 are shown as Embodiment 4 of the wireless communication system of the present invention. Steps S40-S43 are the processing of the STA, and steps S44-S49 are the processing of the AP. In addition, the processing of steps S40-S42 and S44-S48 in Embodiment 4 is the same as the processing of steps S30-S32 and S34-S38 in Embodiment 3, while the processing of steps S43 and S49 is different from the processing of steps S33 and S39 in Embodiment 3.

[0099] After determining in step S42 that the data transmission efficiency of simultaneous transmission is good, the predetermined STAx generates a request frame indicating that simultaneous transmission is possible in step S43, and sends it to the AP after obtaining access rights through carrier sense and random backoff control. This request frame is the same as the request frame sent by STA1 to the AP in Embodiment 3, and may also contain combined information of the STAs transmitting simultaneously or their terminal information. On the other hand, after the AP again determines in step S47 that the data transmission efficiency of simultaneous transmission is good, in step S49, for the selected STAs transmitting simultaneously, it generates and sends a trigger frame to indicate simultaneous uplink transmission.

[0100] Thus, the characteristic of Embodiment 4 is that the AP sends a trigger frame based on the access rights obtained by a predetermined STAx, just as in Embodiment 2. Therefore, similar to Embodiment 2, if an STA obtains access rights and sends a request frame, and the AP receiving the request frame wants to send a trigger frame during the SIFS time, transmission can be reliably performed using the access rights obtained by the STA, and simultaneous transmission can begin. Furthermore, if we assume the time from when the AP receives a request frame and sends a trigger frame until the corresponding STA completes simultaneous transmission, and set NAVs for other STAs not selected for simultaneous transmission based on the request frame sent by the STA or other received / transmitted RTS / CTS frames, then the STA selected based on the AP's trigger frame can reliably perform simultaneous transmission.

[0101] In the above embodiments 1 to 4, the process of simultaneous uplink transmission from multiple STAs was described. However, when downlink data frames are being sent to STAs from the AP, simultaneous downlink and uplink transmissions can also be performed continuously. For example, in embodiments 1 to 4, when the AP starts controlling simultaneous uplink transmission, it determines whether a downlink data frame is present. If no downlink data frame is present, a trigger frame is sent as in each embodiment, causing the STAs selected for simultaneous transmission to transmit simultaneously. On the other hand, if a downlink data frame is present in the AP, the trigger frame can be sent after the downlink data frame and ACK are received and transmitted. In this case, the downlink data frame and the trigger frame can be sent together, with the uplink data frame plus the downlink data frame's ACK, based on the common setting of the STA as the destination in the downlink direction and the STAs performing simultaneous uplink transmission. Alternatively, the downlink data frame can be sent after the AP's trigger frame and the STAs' simultaneous uplink transmission. In this continuous processing case, the access rights obtained by the AP or STA are assumed to be access rights for their transmission and reception time periods.

[0102] In Embodiments 1 and 3 described above, the trigger frame can set a NAV that prevents surrounding terminals from sending data. The period length of the NAV set here is based on the collected terminal information. Several methods can be considered for setting and modifying the NAV.

[0103] (1) The trigger frame does not set NAV, but only requests the transmission of data frames. In this case, the STA can send an RTS frame before sending data frames, and the AP can return a CTS frame to start the transmission of data frames.

[0104] (2) The NAV is set by polling a trigger frame or RTS frame for a STA that can be the destination. In this case, the trigger frame or RTS frame sets the NAV for the surrounding terminals and collects data frames from more than one STA. Finally, the trigger frame is sent again to trigger simultaneous transmission.

[0105] (3) The AP sends a trigger frame or RTS frame containing multiple destination addresses for request responses, and sets the NAV for surrounding terminals. Furthermore, the NAV period length can be changed by having the STAs specified by the address in the trigger frame respond sequentially to the trigger frame or by responding simultaneously via multiplexing. Finally, the trigger frame is sent again to trigger simultaneous transmission.

[0106] (4) Send a first trigger frame as a trigger frame, confirm the return of the second trigger frame from the designated STA, send the third trigger frame again, and receive a data frame from the STA that returned the second trigger frame. In this method, the first trigger frame sets the NAV period length for the surrounding terminals based on the collected terminal information, or sets a predetermined NAV period length. The STA receives the first trigger frame and sends the second trigger frame. At this time, multiple STAs can send the second trigger frame simultaneously, or send the second trigger frame at a predetermined time according to a first specified time, or send the first trigger frame to each STA one by one so that the second trigger frames return sequentially. The AP sends the third trigger frame as an instruction to the STA that normally receives the second trigger frame. At this time, the NAV period length can be changed by specifying the third trigger frame based on the combination of terminal information contained in the second trigger frame and the normal transmission of the second trigger frame. Here, the first and second trigger frames set the NAV in the same way as the exchange of RTS / CTS, and the NAV of the surrounding terminals set by the first trigger frame can also be canceled when the third trigger frame does not occur. The third trigger frame may contain information as a synchronization signal for simultaneous transmission by the STA, or have the function of transferring the right to transmit. When the third trigger frame serves as a transfer of transmission rights, it is not necessary to send the third trigger frame directly after receiving the second trigger frame. Instead, the third trigger frame can be sent after a single STA or multiple STAs have transmitted downlink data frames.

[0107] In embodiments 2 and 4 above, the request frame sent by the STA can set a NAV (Network Access Variable) that is prohibited from being sent by surrounding terminals. The NAV period length set here is a value notified in advance by the AP, or calculated based on the length of the data frame that the STA wants to send. Several methods can be considered for setting and modifying the NAV.

[0108] (1) The request frame does not set NAV, and requests the transmission of the trigger frame. The order after the trigger frame is sent can be communicated through the three methods shown in Embodiments 1 and 3 above.

[0109] (2) The NAV is set by polling with request frames, and a trigger frame is requested to be sent. In this case, the request frame sets the NAV for the surrounding terminals, causing the AP to send a trigger frame. At this time, the AP can determine and change the combination of STAs that send uplinks simultaneously based on information such as the NAV period length specified by the STA. After the trigger frame is sent, communication can be carried out using the three methods shown in Embodiments 1 and 3 above. Since the NAV has been set once in the request frame, the NAV period length can be changed through subsequent communication.

[0110] In Examples 1-4 above, the MCS index representing the modulation scheme and coding rate for user data can be determined in the AP or STA as follows: The MCS index can be determined by considering the communication results to date, or by considering the penalty caused by simultaneous transmission from multiple users. When determining by considering the communication results to date, the MCS index that indicates successful communication under the same conditions of simultaneous transmission from multiple users can be used, or the MCS index with fewer bits per data frame compared to the MCS index indicating failed communication under the same conditions of simultaneous transmission from multiple users can be used. When using the penalty caused by simultaneous transmission from multiple users, the MCS index for single-user communication is determined by the number of STAs multiplexed due to simultaneous transmission from multiple users, or by the multiplexing method and the number of multiplexed STAs for simultaneous transmission from multiple users. The multiplexing method is, for example, Frequency Division Multiple Access (FDMA), Space Division Multiple Access (SDMA, MU-MIMO), or a multiplexing method using both. In the case of FDMA, inter-user interference due to frequency deviation, and in the case of MU-MIMO, inter-user interference due to incomplete spatial signal separation, can lead to a degraded communication quality. Therefore, it is advisable to change the MCS index accordingly to an index corresponding to a lower number of bits. Generally speaking, MU-MIMO has a greater penalty than FDMA. The following methods can be considered as examples of methods for determining the MCS index used by the STA in a data frame.

[0111] (1) The AP informs the user of the number of multiplexing and its multiplexing method, and determines the MCS index corresponding to the lower number of bits compared to the case of single-user communication by referring to the penalty in the table pre-stored in the STA based on the information.

[0112] (2) Estimate the number of multiplexes used by users in the AP and their multiplexing methods. Based on the assumed number of multiplexes and multiplexing methods, refer to the penalty in a pre-stored table to determine the MCS index corresponding to the lower number of bits compared to the case of single-user communication. Alternatively, when determining the penalty, the penalty can also be calculated for user combinations based on the propagation characteristics information of the channel state and the correlation value of the STA.

[0113] (3) Based on the AP notification of the penalty caused by multiple users sending at the same time, determine the MCS index corresponding to the lower number of bits compared to the case of communication with a single user.

[0114] (4) The MCS index used in the simultaneous sending of notifications from the AP to multiple users is used, and the specified MCS index is used.

[0115] As a specific indicator of the penalty, a value indicating a reduction of several bits from the available MCS index options can be used, or a value obtained by quantizing the signal-to-interference-noise ratio (SINR) as a reduction, or by quantizing a number less than 1 or a value expressed in decibels. For example, in the case of enabling two STAs to perform uplink communication based on MU-MIMO, it is possible to notify that the MCS index is reduced by one or that the SINR is reduced by 2 dB.

[0116] Symbol Explanation

[0117] AP Wireless LAN Base Station Device

[0118] STA Wireless LAN Terminal Device

[0119] 11. Wireless Communications Department

[0120] 12 Control Department

[0121] 13 Information Management Department

[0122] 14 Simultaneously send the judgment unit

[0123] 15 Access Control Department

Claims

1. A wireless LAN base station device, connected to multiple wireless LAN terminal devices, enabling simultaneous transmission of wireless frames from the multiple wireless LAN terminal devices via a multiplexing connection, characterized in that it comprises: A terminal information collection unit collects terminal information from the plurality of wireless LAN terminal devices, the terminal information being used to control simultaneous transmission; The triggering unit sends a trigger frame to the wireless LAN terminal devices that are transmitting simultaneously. The trigger frame contains wireless communication resource information that each wireless LAN terminal device can utilize. as well as Multiple CSMA / CA units acquire channel access rights, which are used to transmit downlink data frames corresponding to each access type. Any one of the plurality of CSMA / CA units is used to acquire channel access rights for sending the trigger frame.

2. A wireless LAN communication method, enabling multiple wireless LAN terminal devices to simultaneously transmit wireless frames to a wireless LAN base station device via a multiplexing connection, characterized in that the wireless LAN communication method includes the following steps: Terminal information is collected from the plurality of wireless LAN terminal devices, and the terminal information is used to control simultaneous transmission; For the trigger frame sent by the wireless LAN terminal devices that are transmitting simultaneously, the trigger frame contains wireless communication resource information that each wireless LAN terminal device can utilize. as well as Any one of the plurality of CSMA / CA units is used to acquire channel access rights for transmitting the trigger frame, wherein the plurality of CSMA / CA units acquire channel access rights for transmitting downlink data frames corresponding to each access type.

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