Wireless LAN terminal, wireless LAN base station, and method

Abstract

To improve communication efficiency.SOLUTION: A wireless LAN terminal receives a trigger frame containing a first association identifier in regard to a first resource unit for a random access by a plurality of wireless LAN terminals after an association so as to be common with the plurality of wireless LAN terminals after the association with each wireless LAN base station, and a second association identifier in regard to a second resource unit for the random access by the plurality of wireless LAN terminals before the association so as to be common with the plurality of wireless LAN terminals before the association with each wireless LAN base station, determines whether the trigger frame contains the second association identifier, and transmits up-link data to each wireless LAN base station by using the second source unit for the random access in the case where the second association identifier is contained in the trigger frame, and each wireless LAN terminal is not associated with each wireless LAN base station.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a wireless LAN (Local Area Network) system, a wireless LAN base station, a wireless LAN terminal, and a communication method. [Background technology]

[0002] In the wireless LAN standard IEEE (Institute of Electrical and Electronics Engineers) 802.11, the next-generation communication method 802.11ax (HEW: High Efficiency WLAN (Wireless LAN)) is being studied by the Task Group TGax. In terms of elemental technologies, the next-generation communication method 802.11ax is expected to adopt a new modulation and demodulation method (1024QAM (Quadrature Amplitude Modulation)), support MU-MIMO (Multi-User Multi-Input Multi-Output) for uplink, and introduce OFDMA (Orthogonal frequency-division multiple access).

[0003] Fig. 1 is a diagram showing an example of a basic configuration of a wireless LAN system. This wireless LAN system includes an access point AP and multiple terminals STA1 to STAn. Hereinafter, when the terminals STA1 to STAn are not specified, they will be referred to as terminals STA. Note that, although three terminals STA are shown as an example in Fig. 1, the number of terminals STA may be two or more (i.e., n is two or more). The access point AP and the multiple terminals STA1 to STAn form a network called a BSS (Basic Service Set).

[0004] In CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) communication (DCF: Distributed Coordination Function), a common communication mode of IEEE 802.11, only one terminal STA can communicate with an access point AP in the uplink at a time within the same BSS. In uplink OFDMA and uplink MU-MIMO uplink multi-user (UL MU: Uplink Multi-user) communication introduced in IEEE 802.11ax (HEW), the access point AP centrally controls multiple terminals STA 1 to STA n, divides communication resources into multiple resource units (resource units (RU: Resource Units)), and assigns the resource units to multiple terminals STA 1 to STA n. This allows multiple terminals STA 1 to STA n to communicate simultaneously.

[0005] The procedure for uplink multi-user communication will be described with reference to FIG. 2 (see Non-Patent Document 1). Step 1: The terminal STA notifies the access point AP in advance of a buffer status indicating that there is uplink data waiting to be transmitted.

[0006] Step 2: The access point AP transmits a trigger frame for allocating resource units RU to multiple terminals STA1 to STAn in the BSS (time t1). Here, it is assumed that four resource units RU are notified. The access point AP allocates the four resource units RU to different terminals STAs. For this reason, the access point AP includes in the trigger frame information on the four resource units RU and terminal identifiers (e.g., AIDs (Association IDs)) that specify the terminals STAs to which the four resource units RU are to be allocated. When the terminal ID that specifies the terminal STA is included in the trigger frame, the terminal STA transmits a UL MU PPDU (Physical Layer Convergence Protocol (PLCP) Protocol Data Unit) frame including uplink data to the access point AP using the resource unit RU allocated to it (time t2). Here, four terminals STA1 to STA4 are transmitting uplink data to the access point AP.

[0007] Step 3: The access point AP transmits an ACK frame (Acknowledgement frame) notifying each of the terminals STA1 to STAn in the BSS whether or not the communication has been successful (time t3).

[0008] However, in the uplink multi-user communication described in Fig. 2, there is a problem that the terminal STA cannot necessarily notify the access point AP of the buffer status in advance. Also, when the AID is used as the terminal ID, there is a problem that the terminal STA before association cannot perform uplink multi-user communication (see Non-Patent Document 2).

[0009] In particular, the inability of pre-associated terminal STAs to perform uplink multi-user communication is a very serious problem, because in a highly congested WLAN environment, management frames such as Association Request and Probe Request, transmitted by pre-associated terminal STAs, account for a large proportion of traffic. In order to solve this problem, a random access method for uplink multi-user communication has been studied (see clause 4.5 of non-patent document 3).

[0010] A random access procedure in uplink multi-user communication will be described with reference to Fig. 3. The random access procedure described below is applicable to both uplink OFDMA and uplink MU-MIMO uplink multi-user communication. Step 1: A terminal STA that has uplink data waiting to be transmitted sets its own backoff counter to an initial value, which is selected randomly within the range from 0 to the maximum count value of the backoff counter.

[0011] Step 2: The access point AP transmits a trigger frame for random access (TF-R) for allocating resource units RU to multiple terminals STA1 to STAn in the BSS (time t1). Here, the access point AP notifies five resource units RU1 to RU5. The access point AP also does not allocate the resource units RU1 to RU5 to a specific terminal STA, but makes them randomly accessible. For this reason, the access point AP includes in the random access trigger frame information on the resource units RU1 to RU5 and a special terminal ID (AID0 in the example of FIG. 3) indicating that each of the resource units RU1 to RU5 is randomly accessible. A terminal STA having a non-zero count value in its back-off counter decrements the count value by five, which is the number of resource units RU1 to RU5 to which the special terminal ID is assigned, at predetermined time intervals. As a result, the terminal STA whose count value has reached 0 selects one resource unit RU and transmits a UL MU PPDU frame including uplink data to the access point AP using the selected resource unit RU (time t2). Here, the terminal STA2 transmits uplink data using resource unit RU1, and the terminal STA1 transmits uplink data using resource unit RU3.

[0012] Step 3: The access point AP transmits an ACK frame to multiple terminals STA1 to STAn in the BSS to notify whether communication was successful or not (time t3). If the initial values ​​randomly set in the backoff counters of the terminal STAs are the same, a collision of uplink data may occur at time t2. If a terminal STA is unable to communicate correctly due to a collision of uplink data or the like, it can determine this from the ACK frame. Therefore, a terminal STA that is unable to communicate correctly returns to step 1, resets the random initial value in its backoff counter, and waits for an opportunity to resend the uplink data. [Prior art documents] [Non-patent literature]

[0013] [Non-Patent Document 1] IEEE 802.11-15 / 0365r0, “UL MU procedure”, 2015-03-09 [Non-Patent Document 2] IEEE 802.11-15 / 0875r1, “Random Access with Trigger Frames using OFDMA”, 2015-07-13 [Non-Patent Document 3] IEEE 802.11-15 / 0132r15, “Specification Framework for TGax”, 2016-01-28 Summary of the Invention [Problem to be solved by the invention]

[0014] However, the random access procedure in uplink multi-user communication described in FIG. 3 has a problem in that the communication efficiency is very low because of the possibility of uplink data collisions.

[0015] Therefore, one of the objects of the present disclosure is to provide a wireless LAN system, a wireless LAN base station, a wireless LAN terminal, and a communication method that can improve communication efficiency in uplink multi-user communication. [Means for solving the problem]

[0016] In one aspect, a wireless LAN (Local Area Network) system includes: A wireless LAN base station, A plurality of wireless LAN terminals that perform uplink multi-user communication with the wireless LAN base station; The wireless LAN base station includes: Transmitting a trigger frame for allocating a predetermined resource unit to the plurality of wireless LAN terminals, the trigger frame including a terminal ID (Identifier) ​​that specifies a pre-association wireless LAN terminal among the plurality of wireless LAN terminals; The wireless LAN terminal before association is If the temporary terminal ID designating the terminal itself is included in the trigger frame, the terminal selects the specified resource unit and transmits uplink data to the wireless LAN base station.

[0017] In one embodiment, a wireless LAN (Local Area Network) base station includes: A wireless LAN base station that performs uplink multi-user communication between a plurality of wireless LAN terminals, The Communications Department and A processor, The processor, generating a trigger frame for allocating a predetermined resource unit, the trigger frame including a terminal ID (Identifier) ​​for specifying a pre-association wireless LAN terminal among the plurality of wireless LAN terminals; The communication unit is The trigger frame is transmitted to the plurality of wireless LAN terminals.

[0018] In one aspect, a wireless LAN (Local Area Network) terminal includes: A wireless LAN terminal among a plurality of wireless LAN terminals that perform uplink multi-user communication with a wireless LAN base station, The Communications Department and A processor, The processor, Determine whether the terminal itself is a pre-association wireless LAN terminal and whether a trigger frame for allocating a predetermined resource unit received from the wireless LAN base station includes a terminal ID (Identifier) ​​that specifies the terminal itself; The communication unit is Based on the determination, the specified resource unit is selected and uplink data is transmitted to the wireless LAN base station.

[0019] In one aspect, a method of communication includes: A communication method by a wireless LAN base station for performing uplink multi-user communication between a plurality of wireless LAN (Local Area Network) terminals, comprising: A trigger frame for allocating a predetermined resource unit, which includes a terminal ID (Identifier) ​​that specifies a pre-associated wireless LAN terminal among the plurality of wireless LAN terminals, is transmitted to the plurality of wireless LAN terminals.

[0020] In another aspect, a communication method comprises: A communication method by one of a plurality of wireless LAN terminals performing uplink multi-user communication with a wireless LAN (Local Area Network) base station, comprising: If the terminal itself is a wireless LAN terminal before association and the trigger frame for allocating a specified resource unit received from the wireless LAN base station contains a terminal ID (identifier) ​​that specifies the terminal itself, the terminal selects the specified resource unit and transmits uplink data to the wireless LAN base station. Effect of the Invention

[0021] According to the above-described aspect, an effect is obtained in that communication efficiency can be improved in uplink multi-user communication. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram illustrating an example of a basic configuration of a wireless LAN system. [Diagram 2] FIG. 1 is a diagram explaining the procedure of uplink multi-user communication. [Diagram 3] FIG. 1 is a diagram explaining the random access procedure in uplink multi-user communication. [Figure 4] FIG. 1 is a diagram showing an example of the configuration of a wireless LAN system in some aspects. [Diagram 5] FIG. 11 is a diagram illustrating an example 1 of a temporary terminal ID that specifies a terminal before association, from a certain viewpoint. [Figure 6] FIG. 11 is a diagram illustrating an example 2 of a temporary terminal ID that specifies a terminal before association, from a certain viewpoint. [Figure 7] FIG. 1 illustrates an example of two-stage uplink multi-user communication in one aspect. [Figure 8] FIG. 2 is a block diagram showing an example of the configuration of an access point from a certain viewpoint. [Figure 9] FIG. 2 is a block diagram showing a configuration example of a terminal from a certain viewpoint. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 4 is a diagram showing a configuration example of a wireless LAN system in some aspects. The wireless LAN system in some aspects includes an access point AP and a plurality of terminals STA 1 to STA n. The access point AP is an example of a wireless LAN base station, and the terminals STA 1 to STA n are examples of wireless LAN terminals. Hereinafter, when the terminals STA 1 to STA n are not specified, they will be referred to as terminals STA. Note that, although six terminals STA are shown as an example in FIG. 4, the number of terminals STA may be two or more (i.e., n is two or more). The access point AP and the terminals STA 1 to STA n form a BSS. Furthermore, the wireless LAN system in some aspects is applicable to both uplink OFDMA and uplink MU-MIMO uplink multi-user communications.

[0024] Here, it is assumed that the terminals STA1 to STA3 are terminals that have already associated with the access point AP, and the terminals STA4 and STA5 are terminals that have not yet associated with the access point AP. As shown in Table 1 below, the associated terminals STA1 to STA3 have AID1 to AID3 set as terminal IDs, but the terminals STA4 and STA5 before association have no AID set. [Table 1]

[0025] As mentioned above, the random access procedure in uplink multi-user communication described in Figure 3 has very low communication efficiency. In addition, since a terminal STA before association can only participate in random access, the communication efficiency will remain low until association is achieved.

[0026] From a certain point of view, therefore, it is intended to improve communication efficiency by introducing a temporary terminal ID that specifies a terminal STA before association. The temporary terminal ID that specifies a terminal STA before association will be explained below.

[0027] (1) Temporary Device ID (1-1) Example 1 of temporary device ID FIG. 5 is a diagram illustrating an example 1 of a temporary terminal ID that specifies a terminal STA before association from a certain point of view. At time t1, the access point AP transmits a trigger frame notifying a plurality of terminals STA1 to STAn in the BSS of resource units RU. In this example 1, at time t1, the access point AP notifies five resource units RU1 to RU5. The access point AP also allocates resource units RU1 to RU3 to associated terminals STA1 to STA3, respectively, but does not allocate resource units RU4 and RU5 to a specific terminal STA, and sets them as randomly accessible. The access point AP includes, in the trigger frame at time t1, information on resource units RU1 to RU5, AID1 to AID3 specifying terminals STA1 to STA3 to which resource units RU1 to RU3 are allocated, and AID0, which is a special value indicating that resource units RU4 and RU5 are randomly accessible.

[0028] The trigger frame at time t1 includes AID 1 to AID 3, which specify the terminals STA 1 to STA 3 to which the resource units RU 1 to RU 3 are assigned. At time t2, the terminals STA 1 to STA 3 specified by AID 1 to AID 3 use the resource units RU 1 to RU 3 assigned to them, respectively, to transmit UL MU PPDU frames including uplink data to the access point AP. The trigger frame at time t1 also includes AID 0, which indicates that the resource units RU 4 and RU 5 are randomly accessible. Therefore, in this example 1, at time t2, the terminal STA 5 accesses the resource unit RU 4, obtains the access right to the resource unit RU 4, and transmits a UL MU PPDU frame including uplink data to the access point AP using the resource unit RU 4. In this example 1, a collision of uplink data occurs for the resource unit RU 5, and correct communication is not possible. In this way, in the UL MU PPDU frame at time t2, two resource units RU4 and RU5 are randomly accessible, and there is a possibility of uplink data collision. Therefore, communication efficiency is low. After that, the access point AP transmits an ACK frame to notify the multiple terminals STA1 to STAn in the BSS of whether the communication was successful or not.

[0029] At time t3, the access point AP transmits a trigger frame notifying a plurality of terminals STA1 to STAn in the BSS of resource units RU. In this example 1, at time t3, the access point AP notifies five resource units RU1 to RU5, similar to the trigger frame at time t1. The access point AP assigns resource units RU1 to RU3 to the associated terminals STA1 to STA3, respectively, and does not assign resource unit RU5 to a specific terminal STA, setting it as being randomly accessible. On the other hand, as an example in which the pre-associated terminal STA5 still has uplink data waiting to be transmitted, the access point AP assigns resource unit RU4 to the pre-associated terminal STA5. Since terminal STA5 is a pre-associated terminal STA, no AID is set.

[0030] Therefore, in this example 1, the access point AP designates the terminal STA 5 before association by a temporary terminal ID that can identify the terminal STA 5, as shown as UAID 5 in FIG. 5. The UAID 5 may be designed so that the values ​​generated independently by the access point AP and the terminal STA 5 match. For example, the access point AP and the terminal STA 5 may process the MAC (Media Access Control) address of the terminal STA 5 by a predetermined process and generate the UAID 5 so that it fits into an information element (14 bits) that stores the AID in the trigger frame. As another example, the access point AP and the terminal STA 5 may generate information indicating that the terminal ID is temporary as the UAID 5 by adding one or more bits to a normal AID value. However, the access point AP and the terminal STA 5 need to generate the UAID 5 so that it can be distinguished from a normal AID value. When the terminal STA 5 becomes associated and an AID value is set in the terminal STA 5, the access point AP and the terminal STA 5 delete the UAID 5, and the management of the UAID 5 is completed.

[0031] As a result, in the trigger frame at time t3, the access point AP will include information on resource units RU1 to RU5, AID1 to AID3 specifying the terminals STA1 to STA3 to which resource units RU1 to RU3 will be assigned, UAID5 which is a temporary terminal ID specifying the terminal STA5 to which resource unit RU4 will be assigned, and AID0 which indicates that resource unit RU5 is randomly accessible.

[0032] The trigger frame at time t3 includes AID1 to AID3, which specify the terminals STA1 to STA3 to which the resource units RU1 to RU3 are assigned. At time t4, the terminals STA1 to STA3 specified by AID1 to AID3 transmit UL MU PPDU frames including uplink data to the access point AP using the resource units RU1 to RU3 assigned to them, respectively. The trigger frame at time t3 also includes UAID5, which is a temporary terminal ID specifying the terminal STA5 to which the resource unit RU4 is assigned. Here, the terminal STA5 also generates UAID5 as a temporary terminal ID specifying itself, and compares the generated UAID5 with the terminal ID transmitted from the access point AP. In this example 1, since the terminal ID transmitted from the access point AP is UAID5, the terminal STA5 determines that the terminal ID specifying itself is included in the trigger frame. The terminal STA5 specified by UAID5 transmits a UL MU PPDU frame including uplink data to the access point AP using the resource unit RU4 allocated to it. The trigger frame at time t3 also includes AID 0 indicating that the resource unit RU5 is randomly accessible. In this example 1, a terminal STAX other than the terminals STA1 to STA3 and STA5 accesses the resource unit RU5, acquires the right to access the resource unit RU5, and transmits a UL MU PPDU frame including uplink data to the access point AP using the resource unit RU5. In this way, in the UL MU PPDU frame at time t4, the resource unit RU4 can be allocated to the terminal STA5 before association. Therefore, no collision of uplink data occurs in the resource unit RU4. As a result, only the randomly accessible resource unit RU5 may cause a collision of uplink data, improving communication efficiency. After that, the access point AP transmits an ACK frame to the terminals STA1 to STAn in the BSS to notify whether the communication is successful or not.

[0033] Terminal STA X, which transmitted uplink data using resource unit RU 5 at time t4, can be specified by UAID even if it is a terminal STA before association. This allows the access point AP to allocate resource unit RU 5 to terminal STA X the next time. As a result, the next time, no collision of uplink data will occur even with resource unit RU 5, further improving communication efficiency.

[0034] (1-2) Temporary Device ID Example 2 FIG. 6 is a diagram illustrating an example 2 of a temporary terminal ID that specifies a terminal STA before association, from a certain point of view. The transmission of the trigger frame at time t1 and the transmission of the UL MU PPDU frame at time t2 are the same as in Fig. 5. Also, similar to Fig. 5, it is assumed that after the transmission of the UL MU PPDU frame at time t2, the access point AP transmits an ACK frame.

[0035] At time t3, the access point AP transmits a trigger frame notifying a plurality of terminals STA1 to STAn in the BSS of resource units RU. Here, the access point AP notifies five resource units RU1 to RU5, similar to the trigger frame at time t1. The access point AP assigns resource units RU1 to RU3 to the associated terminals STA1 to STA3, respectively, and does not assign resource unit RU5 to a specific terminal STA, setting it as being randomly accessible. On the other hand, as an example in which the pre-associated terminal STA5 still has uplink data waiting to be transmitted, the access point AP assigns resource unit RU4 to the pre-associated terminal STA5. Since terminal STA5 is a pre-associated terminal STA, no AID is set.

[0036] Therefore, in this example 2, the access point AP designates the terminal STA 5 before association by a temporary terminal ID that is specially defined as NULL in FIG. 6 and is a common value common to the terminals STA 1 to STA n. The temporary terminal ID (for example, NULL) may be an AID value with all bits set to 0, or may be another bit with 1 or more. The access point AP includes NULL, which is a temporary terminal ID that designates the terminal STA 5 to which the resource unit RU 4 is assigned, in the trigger frame at time t3. However, since NULL is a common value, even if the terminal STA 5 receives a trigger frame including NULL, it cannot immediately determine whether the trigger frame designates the terminal STA 5 or not. However, the terminal STA 5 can know from the ACK frame received from the access point AP immediately before time t3 that the transmission of uplink data at time t2 was successful. From this, the terminal STA 5 can indirectly know that NULL designates the terminal STA 5. Note that the common value that is the temporary terminal ID is not limited to NULL. However, the access point AP needs to generate a common value so that it can be distinguished from a normal AID value.

[0037] As a result, in the trigger frame at time t3, the access point AP will include information on resource units RU1 to RU5, AID1 to AID3 specifying the terminals STA1 to STA3 to which resource units RU1 to RU3 will be assigned, NULL which is a temporary terminal ID specifying the terminal STA5 to which resource unit RU4 will be assigned, and AID 0 which indicates that resource unit RU5 is randomly accessible.

[0038] The trigger frame at time t3 includes AID1 to AID3, which specify the terminals STA1 to STA3 to which the resource units RU1 to RU3 are assigned. At time t4, the terminals STA1 to STA3 specified by AID1 to AID3 transmit UL MU PPDU frames including uplink data to the access point AP using the resource units RU1 to RU3 assigned to them, respectively. The trigger frame at time t3 also includes NULL, which is a temporary terminal ID specifying the terminal STA5 to which the resource unit RU4 is assigned. However, even if the terminal STA5 receives a trigger frame including NULL, which is a common value, it cannot immediately determine whether the trigger frame specifies the terminal STA5 or not. However, the terminal STA5 knows that the transmission of uplink data at time t2 was successful from the ACK frame received just before time t3. From this, the terminal STA5 can determine that NULL specifies the terminal STA5. Therefore, the terminal STA5 designated as NULL transmits a UL MU PPDU frame including uplink data to the access point AP using the resource unit RU4 allocated to itself. Also, the trigger frame at time t3 includes AID 0 indicating that the resource unit RU5 is randomly accessible. Therefore, here, the terminal STA1 to STA3 and the terminal STAX other than STA5 access the resource unit RU5, obtain the access right to the resource unit RU5, and transmit a UL MU PPDU frame including uplink data to the access point AP using the resource unit RU5. In this way, in the UL MU PPDU frame at time t4, the resource unit RU4 can be allocated to the terminal STA5 before association. Therefore, no collision of uplink data occurs in the resource unit RU4. As a result, only the randomly accessible resource unit RU5 is likely to cause a collision of uplink data, improving communication efficiency.Thereafter, the access point AP transmits an ACK frame to the multiple terminals STA1 to STAn in the BSS to notify them of whether or not the communication was successful.

[0039] Terminal STA X, which transmitted uplink data using resource unit RU 5 at time t4, can be specified by NULL even if it is a terminal STA before association. Furthermore, terminal STA X can determine that it was successful in transmitting uplink data using resource unit RU 5 at time t4 based on the ACK frame it receives from access point AP. This allows access point AP to allocate resource unit RU 5 to terminal STA X the next time. As a result, the next time, no collision of uplink data will occur even with resource unit RU 5, further improving communication efficiency.

[0040] As described above, in one aspect, a temporary terminal ID that specifies a terminal STA before association is introduced, and when the access point AP allocates a resource unit RU to a terminal STA before association, the access point AP includes the temporary terminal ID that specifies the terminal STA before association in a trigger frame that notifies the resource unit RU.

[0041] In this way, the access point AP can assign a resource unit RU to a terminal STA before association by specifying the terminal ID of the terminal before association, so that the terminal STA before association can participate in uplink multi-user communication and transmit uplink data to the access point AP even by a procedure other than random access, thereby improving communication efficiency.

[0042] 5 and 6, the terminal STA transmits a UL MU PPDU frame including uplink data at time t2, but the information transmitted by the terminal STA is not limited to this. The UL MU PPDU frame at time t2 may include a buffer status indicating that there is uplink data waiting to be transmitted instead of the uplink data, or may include a buffer status in addition to the uplink data. When the UL MU PPDU frame includes uplink data and a buffer status, the buffer status indicates that there is uplink data waiting to be transmitted in addition to the uplink data transmitted together with the buffer status.

[0043] Furthermore, from a certain point of view, it is intended to further improve communication efficiency by introducing two-stage uplink multi-user communication. The following describes two-stage uplink multi-user communication.

[0044] (2) Two-stage uplink multi-user communication FIG. 7 is a diagram illustrating an example of two-stage uplink multi-user communication between an access point AP and multiple terminals STA1 to STAn from a certain perspective. From a certain point of view, uplink multi-user communication between an access point AP and multiple terminals STA1 to STAn is performed in two stages, a first stage and a second stage. In the following description, it is assumed that there are five resource units RU1 to RU5.

[0045] (2-1) First Stage In the first stage, random access is performed for uplink multi-user communication. The access point AP allocates resource units RU1 to RU3 to associated terminals STA1 to STA3, respectively, but does not allocate resource units RU4 and RU5 to any particular terminal STA and sets them as randomly accessible. At time t1, the access point AP transmits a trigger frame including information on resource units RU1 to RU5, AID1 to AID3 specifying terminals STA1 to STA3 to which resource units RU1 to RU3 are allocated, and AID0 indicating that resource units RU4 and RU5 are randomly accessible, to multiple terminals STA1 to STAn in the BSS.

[0046] Here, it is assumed that associated terminals STA1 and STA2 and pre-associated terminal STA5 have upstream data waiting to be transmitted. At time t2, upon receiving the trigger frame from the access point AP, the terminals STA1 and STA2 designated by AID 1 and AID 2 use the resource units RU1 and RU2 assigned to them to transmit a UL MU PPDU frame to the access point AP. Here, the terminal STA5 accesses the resource unit RU4 designated by AID 0 and acquires the right to access the resource unit RU4. Therefore, the terminal STA5 transmits a UL MU PPDU frame including a buffer status, not uplink data, to the access point AP using the resource unit RU4. In this way, in the UL MU PPDU frame at time t2, two resource units RU4 and RU5 are randomly accessible, and there is a possibility that uplink data collision occurs. Therefore, the communication efficiency is low. However, since the amount of data of the buffer status itself is small, the time required for the first stage communication, that is, the time during which the communication efficiency is low, is short.

[0047] The access point AP recognizes that there is a terminal STA 5 before association and that there is uplink data waiting to be transmitted due to the transmission of the buffer status. Therefore, the access point AP includes a temporary terminal ID specifying the terminal STA 5 to which the resource unit RU 4 is to be allocated in the trigger frame transmitted in the second stage. After that, the access point AP transmits an ACK frame notifying the multiple terminals STA 1 to STA n in the BSS whether or not the communication was successful. The terminal STA 5 knows whether or not the communication of the buffer status to the access point AP at time t2 was successful due to the ACK frame received from the access point AP.

[0048] (2-2) Second Stage In the second stage, uplink multi-user communication takes place. The access point AP allocates resource units RU1 and RU2 to associated terminals STA1 and STA2, respectively, and allocates resource unit RU4 to unassociated terminal STA5 that has transmitted a buffer status. At time t3, the access point AP transmits a trigger frame including information on resource units RU1 to RU5, AID1 and AID2 that specify terminals STA1 and STA2 to which resource units RU1 and RU2 are allocated, and the above-mentioned temporary terminal ID (e.g., UAID5 or NULL) that specifies terminal STA5 to which resource unit RU4 is allocated, to multiple terminals STA1 to STAn in the BSS. The access point AP may set resource units RU3 and RU5 to be randomly accessible, or may allocate them to a specific terminal STA. The access point AP includes information indicating that resource units RU3 and RU5 are either randomly accessible or allocated to a specific terminal STA in the trigger frame at time t3.

[0049] At time t4, upon receiving the trigger frame from the access point AP, the terminals STA1 and STA2 designated by AID1 and AID2 use the resource units RU1 and RU2 assigned to them to transmit UL MU PPDU frames including uplink data to the access point AP. Since the terminal STA5 is designated by a temporary terminal ID, it can determine that the resource unit RU4 has been assigned to the terminal STA5. Therefore, the terminal STA5 also uses the resource unit RU4 assigned to it to transmit UL MU PPDU frames including uplink data to the access point AP. After that, the access point AP transmits an ACK frame to notify the terminals STA1 to STAn in the BSS of whether the communication was successful or not. In this way, in the second stage communication, the access point AP can assign the resource unit RU4 to the terminal STA5 before association. Therefore, no collision of uplink data occurs in the resource unit RU4. As a result, communication efficiency is improved. Therefore, by performing the second stage communication for a longer period of time than the first stage communication, it is possible to improve the overall communication efficiency.

[0050] As described above, in one aspect, uplink multi-user communication is performed in two stages, a first stage and a second stage. In the first stage, the access point AP transmits a trigger frame containing a special value indicating that the resource unit RU is randomly accessible, and the pre-associated terminal STA transmits a buffer status using the resource unit RU. In the second stage, the access point AP assigns a resource unit RU to the pre-associated terminal STA that transmitted the buffer status in the first stage, and transmits a trigger frame containing a temporary terminal ID that specifies the pre-associated terminal STA.

[0051] Therefore, in the second stage communication, no collisions of upstream data occur, and communication efficiency can be improved. Therefore, by taking longer to perform the second stage communication than the first stage communication, the overall communication efficiency can be improved.

[0052] In Fig. 7, the terminal STA transmits a UL MU PPDU frame including a buffer status at time t2, but the information transmitted by the terminal STA is not limited to this. The UL MU PPDU frame may include uplink data in addition to the buffer status. When the UL MU PPDU frame includes uplink data and a buffer status, the buffer status indicates that there is uplink data waiting to be transmitted in addition to the uplink data transmitted together with the buffer status.

[0053] A configuration example of an access point AP from a certain viewpoint will be described below. Fig. 8 is a block diagram showing a configuration example of an access point AP from a certain viewpoint. The access point AP includes a communication unit 11 and a processor 12. The processor 12, which is a CPU (Central Processing Unit) or the like, executes a program stored in a memory to realize the above-mentioned processing of the access point AP.

[0054] The communication unit 11 is configured to perform wireless communication with a plurality of terminals STA, specifically, uplink multi-user communication. The processor 12 is coupled to the communication unit 11 and configured to control the communication unit 11 to perform the above-mentioned processing of the access point AP. For example, the processor 12 generates a trigger frame for allocating a predetermined resource unit RU, the trigger frame including a terminal ID that specifies a pre-associated terminal STA among a plurality of terminal STAs. The communication unit 11 transmits the trigger frame generated by the processor 12 to a plurality of terminals STAs.

[0055] A configuration example of a terminal STA from a certain viewpoint will be described below. Fig. 9 is a block diagram showing a configuration example of a terminal STA from a certain viewpoint. The terminal STA includes a communication unit 21 and a processor 22. The processor 22, which is a CPU or the like, realizes the above-mentioned processing of the terminal STA by executing a program stored in a memory (not shown).

[0056] The communication unit 21 is configured to perform wireless communication with the access point AP, specifically, uplink multi-user communication. The processor 22 is coupled to the communication unit 21 and configured to control the communication unit 21 to perform the above-mentioned processing of the terminal STA. For example, the processor 22 determines whether or not the processor 22 is a terminal STA before association and whether or not a temporary terminal ID designating the processor 22 is included in a trigger frame for allocating a predetermined resource unit RU received from the access point AP. The communication unit 21 selects a predetermined resource unit RU based on the determination of the processor 22, and transmits uplink data to the access point AP.

[0057] The above-mentioned program can be stored and provided to a computer using various types of non-transitory computer readable media. The non-transitory computer readable media includes various types of tangible storage media. Examples of the non-transitory computer readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), compact disk-read only memories (CD-ROMs), CD-recordables (CD-Rs), CD-rewritables (CD-R / Ws), and semiconductor memories (e.g., mask ROMs, programmable ROMs (PROMs), erasable PROMs (EPROMs), flash ROMs, and random access memories (RAMs)). The program may also be provided to a computer by various types of transitory computer readable media. Examples of the transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path, such as an electric wire or an optical fiber, or via a wireless communication path.

[0058] Although various aspects of the present invention have been described above with reference to the embodiments, the present invention is not limited to the above. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of each aspect of the present invention within the scope of the invention.

[0059] This application claims priority based on Japanese Patent Application No. 2016-048277, filed March 11, 2016, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0060] AP Access point STA, STA 1 to STA n terminals RU 1~RU 5 Resource Units 11 Communications Department 12 processors 21 Communications Department 22 processors

Claims

1. A wireless LAN (Local Area Network) terminal configured to perform uplink multi-user communication with a wireless LAN base station, A memory storing instructions; at least one processor configured to process the instructions; The processor, receiving a trigger frame from the wireless LAN base station, the trigger frame including a first association identifier that is common to a plurality of wireless LAN terminals after association with the wireless LAN base station and related to a first resource unit for random access by the plurality of wireless LAN terminals after the association, and a second association identifier that is common to a plurality of wireless LAN terminals before association with the wireless LAN base station and related to a second resource unit for random access by the plurality of wireless LAN terminals before the association; determining whether the trigger frame includes the second association identifier; When the second association identifier is included in the trigger frame and the wireless LAN terminal is not associated with the wireless LAN base station, the second resource unit for random access is used to transmit uplink data to the wireless LAN base station. Wireless LAN terminal.

2. The transmission is performed by the random access. The wireless LAN terminal according to claim 1.

3. A wireless LAN (Local Area Network) base station configured to perform uplink multi-user communication with a plurality of wireless LAN terminals, A memory storing instructions; at least one processor configured to process the instructions; The processor, generating a trigger frame including a first association identifier common to a plurality of wireless LAN terminals after association with the wireless LAN base station and related to a first resource unit for random access by the plurality of wireless LAN terminals after the association, and a second association identifier common to a plurality of wireless LAN terminals before association with the wireless LAN base station and related to a second resource unit for random access by the plurality of wireless LAN terminals before the association; transmitting the trigger frame to cause the pre-associated WLAN terminals to transmit uplink data to the WLAN base station using the second resource unit for random access; Wireless LAN base station.

4. The transmission of the trigger frame includes transmitting the trigger frame to cause the plurality of pre-association wireless LAN terminals to transmit uplink data to the wireless LAN base station by the random access using a second resource unit for the random access. The wireless LAN base station according to claim 3.

5. 1. A method of a wireless local area network (WLAN) terminal configured for uplink multi-user communication with a WLAN base station, comprising: receiving a trigger frame from the wireless LAN base station, the trigger frame including a first association identifier that is common to a plurality of wireless LAN terminals after association with the wireless LAN base station and related to a first resource unit for random access by the plurality of wireless LAN terminals after the association, and a second association identifier that is common to a plurality of wireless LAN terminals before association with the wireless LAN base station and related to a second resource unit for random access by the plurality of wireless LAN terminals before the association; determining whether the trigger frame includes the second association identifier; When the second association identifier is included in the trigger frame and the wireless LAN terminal is not associated with the wireless LAN base station, the second resource unit for random access is used to transmit uplink data to the wireless LAN base station. Wireless LAN terminal method.

6. 1. A method of a wireless local area network (WLAN) base station configured for uplink multi-user communication with a plurality of wireless LAN terminals, comprising: generating a trigger frame including a first association identifier common to a plurality of wireless LAN terminals after association with the wireless LAN base station and related to a first resource unit for random access by the plurality of wireless LAN terminals after the association, and a second association identifier common to a plurality of wireless LAN terminals before association with the wireless LAN base station and related to a second resource unit for random access by the plurality of wireless LAN terminals before the association; transmitting the trigger frame to cause the pre-associated WLAN terminals to transmit uplink data to the WLAN base station using the second resource unit for random access; Wireless LAN base station method.

Images