Wireless communication system and wireless communication method

Abstract

A wireless communication system according to one embodiment comprises: a communication destination access point; an access point for access transmission; a low-latency requesting terminal that transmits a packet which requires a prescribed low latency; and a non-low-latency requesting terminal that allows transmission of a packet with a longer latency than the low-latency requesting terminal, wherein upon receiving, from the low-latency requesting terminal, request information that indicates an access request to the communication destination access point, the access point for access transmission transmits the request information to the communication destination access point, and the communication destination access point yields an TXOP to the low-latency requesting terminal.

Description

Wireless communication system and wireless communication method

[0001] The present invention relates to a wireless communication system and a wireless communication method in which a wireless terminal acquires an access right.

[0002] For example, in a wireless communication system such as a wireless LAN, in a conventional DCF (Distributed Coordination Function) access method, when an access point (AP) transmits a packet to a wireless terminal (STA), it waits until the medium becomes available, then waits a randomly determined waiting time called backoff, before attempting access. Furthermore, the packet transmitted by the AP in an access attempt may collide with another packet transmission. If there is no collision, the access is successful (see, for example, Non-Patent Document 1).

[0003] On the other hand, if a collision occurs, the AP waits for the backoff time after the end of the occupied time of the other packet before attempting access again. In this way, the AP repeats this operation until the access attempt is successful.

[0004] Furthermore, the conventional method also includes an access method called PCF (Point Coordination Function), which is different from the DCF (Distributed Coordination Function) access method. In PCF access, an AP issues a polling request to STAs associated with the AP, asking whether they wish to request access. STAs that have packets to transmit respond to the polling request and make access.

[0005] Giuseppe Bianchi, “Performance Analysis of the IEEE 802.11 Distributed Coordination Function”, IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 18, NO. 3, MARCH 2000 ,pp535-547

[0006] Hereinafter, the time from when a packet is generated until when the packet is transmitted to the media is defined as the (MAC layer) delay time. Generally, a smaller delay time is preferable, but when the delay time requirement is relatively low, the conventional DCF / PCF can fully satisfy the function. However, when the delay time requirement is high, the conventional method may not be able to satisfy the requirement.

[0007] In DCF, even if the first access attempt is successful, a delay of (waiting time until the medium becomes available) + (backoff time) occurs. In particular, if the packet length of other packets being communicated at the time of the access attempt is long, the delay time becomes longer. Furthermore, if the first access attempt fails, a delay of (waiting time until the medium becomes available) + (backoff time) is added.

[0008] In this case, the backoff time is longer than that of the first access attempt, which has a significant effect on delay. As such, the conventional basic DCF alone can result in long delay times.

[0009] Furthermore, in conventional PCF, if a terminal (LL-STA) having packets that require low latency is late in the polling turn, priority is given to packet transmission by other terminals (NLL-STA) having packets that do not require low latency, which is expected to result in very large delays.

[0010] If a terminal that has packets requiring low latency is fixed, the latency can be reduced by sending polling requests to that terminal on a priority basis frequently, but there is a problem that an increase in polling requests will result in a decrease in MAC efficiency.

[0011] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a wireless communication system and a wireless communication method that can reduce the delay time of terminals that require low latency when terminals that require low latency and terminals that do not require low latency are mixed.

[0012] A wireless communication system according to one embodiment of the present invention comprises a destination access point, an access transmission access point, a low-latency requesting terminal that transmits packets requiring a specified low latency, and a non-low-latency requesting terminal that allows the transmission of packets with a longer latency than the low-latency requesting terminal, wherein when the access transmission access point receives request information from the low-latency requesting terminal indicating an access request to the destination access point, the access transmission access point transmits the request information to the destination access point, and the destination access point allocates a TXOP to the low-latency requesting terminal.

[0013] In addition, a wireless communication method according to one embodiment of the present invention is a wireless communication method performed by a wireless communication system that includes a destination access point, an access transmission access point, a low-latency requesting terminal that transmits packets requiring a specified low latency, and a non-low-latency requesting terminal that allows the transmission of packets with a longer latency than the low-latency requesting terminal, wherein when the access transmission access point receives request information from the low-latency requesting terminal indicating that it is making an access request to the destination access point, it transmits the request information to the destination access point, and the destination access point cedes a TXOP to the low-latency requesting terminal.

[0014] According to the present invention, when terminals that require low delay and terminals that do not require low delay are mixed, it is possible to reduce the delay time of terminals that require low delay.

[0015] FIG. 1 is a diagram illustrating an overview of an exemplary configuration of a wireless communication system according to an embodiment. FIG. 1 is a diagram illustrating an exemplary configuration of a wireless communication system when a dedicated RF for accessing a second AP is provided. FIG. 2 is a diagram illustrating an exemplary configuration of a wireless communication system when an RF unit 32a dedicated for access transmission is provided and MLO is in effect. FIG. 3 is a diagram illustrating a state in which downlink traffic occurs in an LL-STA. FIG. 4 is a diagram illustrating an exemplary operation when downlink traffic occurs in an LL-STA. FIG. 4 is a diagram illustrating an exemplary configuration of a wireless communication system when an LL-STA does not have a dedicated RF unit for access transmission and SLO is in effect. FIG. 5 is a diagram illustrating an exemplary operation of a wireless communication system when an LL-STA does not have a dedicated RF unit for access transmission and SLO is in effect. FIG. 6 is a diagram illustrating an exemplary operation when downlink traffic occurs for an LL-STA that has entered a standby state. FIG. 7 is a diagram illustrating an exemplary operation when an LL-STA that has entered a standby state wishes to transmit an uplink packet. FIG. 8 is a diagram illustrating an exemplary operation of a wireless communication system when an LL-STA does not have a dedicated RF unit for access transmission and MLO is in effect. FIG. 9 is a diagram illustrating an exemplary operation when downlink traffic occurs for an LL-STA that has entered a standby state. 1 is a diagram showing an example of operation when uplink traffic occurs to an LL-STA that has entered a standby state. FIG. 2 is a diagram showing an example of operation when a first AP has a TXOP at the frequency of the RF unit. FIG. 3 is a diagram showing an example of operation when a first AP cede a TXOP. FIG. 4 is a diagram showing a delay time when an uplink packet of an LL-STA or the like occurs during a TXOP period of the first AP or the like. FIG. 5 is a diagram showing a delay time when an uplink packet of an LL-STA or the like occurs during a TXOP period of the first AP or the like. FIG. 6 is a diagram showing a case where the media of the first AP or the like is busy because it is occupied by another STA. FIG. 7 is a diagram showing a delay time of an LL-STA in conventional technology and a delay time of an LL-STA in a wireless communication system according to an embodiment. FIG. 8 is a diagram showing an example of a hardware configuration of a second AP according to an embodiment.

[0016] First, an overview of a wireless communication system according to an embodiment will be described. The LL-STA promptly notifies the AP of an access request from the time a packet is generated, so that the AP can quickly recognize the access request from the LL-STA from the time the packet is generated and transfer the TXOP (transmission opportunity) held by the AP to the LL-STA. Therefore, the LL-STA can shorten the time it takes to transmit a packet.

[0017] In other words, since the AP proactively cedes the TXOP it holds, the TXOP can be controlled in a fine-grained manner, and the waiting time until the TXOP is cede can be shortened.

[0018] The means by which the LL-STA notifies the AP of an access request immediately after a packet is generated is as follows.

[0019] In one embodiment, the wireless communication system includes a destination AP and an access transmission AP. A communication means is provided between the destination AP and the access transmission AP, and an LL-STA establishes associations with multiple APs (including the destination AP and the access transmission AP).

[0020] If the LL-STA obtains an access right to the destination AP in the access attempt, it continues to communicate with the destination AP.

[0021] Furthermore, when the LL-STA acquires the right to access the access transmission AP, the access transmission AP transmits to the destination AP that the LL-STA is requesting access.

[0022] If the destination AP has a TXOP, it cede the TXOP to allow the uplink traffic of the LL-STA to flow. If the destination AP does not have a TXOP, it tries to acquire one, and when it does acquire one, it cede the TXOP to the LL-STA.

[0023] In other words, when uplink traffic occurs, the LL-STA establishes an association with a "relatively easy-to-access AP" (access transmission AP) and, by accessing the AP, transmits an access request to the access transmission AP. The access transmission AP then transmits this information to the AP that actually performs the communication (destination AP).

[0024] Here, a "relatively easy-to-access AP" is an AP that is expected to have a high probability of successful access when an access attempt is made to that AP, and that is expected to have a short time from packet generation to packet transmission.

[0025] Next, the wireless communication system according to an embodiment will be described in more detail with reference to the drawings.

[0026] 1 is a diagram illustrating an overview of a configuration example of a wireless communication system 100 according to an embodiment. The wireless communication system 100 includes one or more first APs 10, which are communication destination APs, and one or more second APs 20, which are auxiliary access transmission APs, and is configured such that an LL-STA 30 and an NLL-STA (not shown) are connected to the first AP 10. The first AP 10 and the second AP 20 are capable of communicating with each other via a predetermined communication means.

[0027] LL-STA 30 establishes associations with multiple APs (two in FIG. 1: first AP 10 and second AP 20). Since LL-STA 30 is always associated with two APs, it can make access attempts on the medium between the two APs.

[0028] If the access attempt on the medium between LL-STA30 and any of the APs is successful, LL-STA30 is able to communicate with the corresponding AP. If the AP with which the access attempt was successful is the first AP 10, LL-STA30 continues communication as is. Furthermore, if the AP with which the access attempt was successful is the second AP 20, LL-STA30 transmits information (request information) indicating an access request to the first AP 10 via the second AP 20 to the first AP 10.

[0029] The information transmitted from the LL-STA 30 to the second AP 20 also includes identification information of the LL-STA 30. When the second AP 20 receives the request information from the LL-STA 30, it transmits the request information to the first AP 10. Thus, the first AP 10 can recognize the access attempt of the subordinate LL-STA 30.

[0030] When the first AP 10 receives the request information and has a TXOP (transmission opportunity period), it grants the TXOP to the LL-STA 30 as soon as possible. Then, the LL-STA 30 transmits uplink information to the first AP 10.

[0031] In this case, the first AP 10, which is the entity that holds the TXOP, cedes the TXOP, so it is expected that the ceding time will be shortened.

[0032] Furthermore, if the first AP 10 does not have a TXOP (Transmission Opportunity Period), it will initiate an access attempt even if there is no downlink traffic. Then, once the first AP 10 acquires access rights, it will immediately grant the TXOP to the LL-STA 30.

[0033] Therefore, the delay time from when an uplink packet is generated at LL-STA30 until LL-STA30 transmits the uplink information to the first AP10 is approximately (waiting time when LL-STA30 attempts to access the medium between it and the second AP20) + (time for the second AP20 to transmit to the first AP10) + (time to cede).

[0034] In this way, it is expected that the surrender time can be shortened, and if LL-STA30 can shorten (the waiting time when attempting to access the media between it and the second AP20) and (the time it takes for the second AP20 to transmit to the first AP10), the delay time from when an uplink packet is generated to when the uplink information is sent to the first AP10 can be shortened.

[0035] The time (the time it takes for the second AP 20 to transmit the information to the destination AP) can be shortened if the communication speed between the second AP 20 and the first AP 10 is fast. Also, if the medium between the second AP 20 and the first AP 10 is free, the waiting time when attempting to access the medium between the second AP 20 and the first AP 10 can be shortened. Therefore, it is desirable for the wireless communication system 100 to select an AP with a relatively free medium as the second AP 20.

[0036] Next, a method will be described in which, when the first AP 10 that has received request information to access the first AP 10 has a TXOP (transmission opportunity period), the first AP 10 assigns the TXOP to the LL-STA 30.

[0037] When the first AP 10 has a TXOP (transmission opportunity period), if the LL-STA 30 receives request information from the second AP 20, the first AP 10 stops transmitting the packet that is currently being transmitted as soon as possible. If the time from when the first AP 10 receives the request information to when the first AP 10 stops transmitting the packet that is currently being transmitted is short, the delay time of the LL-STA 30 can be shortened.

[0038] Next, the first AP 10 recognizes the LL-STA 30 based on the identification information of the LL-STA 30 stored in the request information, and transmits a trigger frame to the LL-STA 30. The trigger frame includes a TXOP channel and permission to transmit uplink packets.

[0039] Then, the LL-STA 30 starts transmitting uplink packets to the first AP 10 on that channel.

[0040] By the above operation, the first AP 10 can transfer the TXOP it holds to the LL-STA 30. Therefore, when the LL-STA 30 wants to transmit an uplink packet, the wireless communication system 100 can immediately notify the first AP 10 of this, transfer the TXOP in a short time, and start transmitting the uplink packet using the TXOP. In this way, the wireless communication system 100 can shorten the delay time of the LL-STA 30.

[0041] Note that the greater the ratio of the TXOP held by the first AP 10 to the total airtime, the greater the effect of reducing the delay time in the wireless communication system 100. Therefore, in order to enhance the effect of reducing the delay time, the wireless communication system 100 may set the TXOP to be longer than the period required to transmit the downlink traffic of the first AP 10.

[0042] Next, the specific configuration and operation of the wireless communication system 100 will be described in detail using the drawings. Here, the description will be divided into a case where a dedicated RF for accessing the second AP 20 is provided and a case where a dedicated RF is not provided. Furthermore, the above two cases will be further divided into a case of single link operation (SLO) and a case of multi-link operation (MLO).

[0043] [When a dedicated RF is provided for accessing the second AP 20] Fig. 2 is a diagram showing an example of the configuration of the wireless communication system 100a when a dedicated RF is provided for accessing the second AP 20. Note that Fig. 2 illustrates the case of MLO.

[0044] The wireless communication system 100a has one or more first APs 10-1 which are communication destination APs, and one or more second APs 20-1 which are auxiliary access transmission APs, and is configured so that an LL-STA 30-1 and multiple STAs 40, each of which is an NLL-STA, connect to the first AP 10-1.

[0045] The first AP 10-1 has, for example, three RF units 12a, 12b, and 12c. The second AP 20-1 has, for example, three RF units 22a, 22b, and 22c. The LL-STA 30-1 has, for example, four RF units 32a, 32b, 32c, and 32d. For example, the RF unit 32a is an RF unit dedicated to access transmission for communicating with the second AP 20-1.

[0046] The LL-STA 30-1 is able to access the first AP 10-1 and the second AP 20-2 using DCF, and the first AP 10-1 and the second AP 20-1 are able to communicate with each other using a predetermined communication means.

[0047] [Case where there is an RF unit 32a dedicated to access transfer and MLO is in effect] Hereinafter, the operation of the wireless communication system 100a will be described taking as an example a case where the LL-STA 30-1 is provided with an RF unit 32a dedicated to access transfer and MLO is in effect.

[0048] 3 is a diagram showing an example of the configuration of a wireless communication system in MLO mode, in which an RF unit 32a dedicated to access transmission is included. In the initial state, the frequencies of the RF units 12a and 12b of the first AP 10-1, which is the destination AP, are assumed to be the same as the frequencies of the RF units 32c and 32b of the LL-STA 30-1, respectively.

[0049] When the first AP 10-1 has many subordinate STAs 40 and it is difficult to obtain access rights, the LL-STA 30-1 also associates with the second AP 20-1, which is different from the first AP 10-1 and to which it is easier to obtain access rights.

[0050] The LL-STA 30-1 sets the frequency of the RF unit 32a to, for example, the frequency of the RF unit 22a, and enters a state in which it can communicate with the second AP 20-1 as well. Then, the LL-STA 30-1 establishes dual association with the first AP 10-1 and the second AP 20-1, and then enters a standby state.

[0051] Next, when downlink traffic to LL-STA 30-1 occurs, if the first AP 10-2 can obtain access rights to the frequency of the RF unit 32c, as shown by the thick arrow in Figure 4, the first AP 10-2 obtains the access rights and sends the downlink traffic to LL-STA 30-2.

[0052] Next, when uplink traffic occurs, LL-STA30-2 first attempts to access using the media of the communication frequency with the first AP10-2 and the communication frequency with the second AP20-2, using the respective frequencies of RF units 32a, 32b, and 32c.

[0053] FIG. 5 is a diagram showing an example of operation when downlink traffic occurs in the LL-STA.

[0054] If the LL-STA 30-2 is granted access rights at the frequency for communication with the first AP 10-2 (the frequency of the RF units 12a and 12b and the RF units 32b and 32c), it transmits uplink traffic at that frequency.

[0055] However, if LL-STA30-2 cannot obtain access rights because the communication frequencies (frequencies of RF units 12a, 12b and RF units 32b, 32c) with the first AP 10-2 are congested, but the communication frequencies (frequencies of RF units 32a and 22a) with the second AP 20-2 are available and LL-STA30-2 can obtain access rights, after obtaining access rights to the second AP 20-2, it transmits request information for the first AP 10-2 to the second AP 20-2.

[0056] The second AP 20-2 notifies the first AP 10-2 of the occurrence of uplink traffic from the LL-STA 30-2 via a predetermined communication means.

[0057] If the first AP 10-2 holds a TXOP at a frequency for communication with the LL-STA 30-2 (the frequency of the RF units 12a and 12b and the frequency of the RF units 32b and 32c), it cedes the TXOP to the LL-STA. The LL-STA 30-2 performs uplink communication using the ceded TXOP (for example, the frequency of the RF units 12a and 32c in FIG. 5). The ceding operation will be described later.

[0058] [When there is an RF unit dedicated to access transfer and SLO is in effect] When the LL-STA has an RF unit dedicated to access transfer and SLO is in effect, it operates in the same manner as in the above-described MLO case.

[0059] [Case where there is no RF unit dedicated to access transfer and SLO is used] Next, the operation of the wireless communication system 100c will be described taking as an example a case where the LL-STA does not have an RF unit dedicated to access transfer and SLO is used.

[0060] Fig. 6 is a diagram showing a configuration example of a wireless communication system 100c when the LL-STA does not have a dedicated RF unit for access transmission and is in SLO. Fig. 7 is a diagram showing an operation example of the wireless communication system 100c when the LL-STA does not have a dedicated RF unit for access transmission and is in SLO.

[0061] The wireless communication system 100c includes one or more first APs 10-3, which are destination APs, and one or more second APs 20-3, which are auxiliary access transmission APs. The system is configured such that an LL-STA 30-3 and a plurality of STAs 40, each of which is an NLL-STA, connect to the first AP 10-3. The LL-STA 30-3 can access the first AP 10-3 and the second AP 20-3 using DCF. The first AP 10-3 and the second AP 20-3 can communicate with each other using a predetermined communication means.

[0062] The first AP 10-3 has an RF unit 14. The second AP 20-3 has an RF unit 24. The LL-STA 30-3 has an RF unit 34.

[0063] If it is difficult for LL-STA30-3 to obtain access rights to the first AP10-3 and it is easy to obtain access rights to the second AP20-3, LL-STA30-3 switches the frequency of RF unit 34 from the frequency of RF unit 14 to the frequency of RF unit 24 and associates with the second AP20-3.

[0064] At this time, LL-STA 30-3 cannot access the frequency of the first AP 10-3, but maintains its association with the first AP 10-3. Then, LL-STA 30-3 notifies the first AP 10-3 via the second AP 20-3 that it has switched the frequency of the RF unit 34 to the frequency of the RF unit 24. The first AP 10-3 recognizes that LL-STA 30-3 has entered a standby state at the frequency of the RF unit 24.

[0065] Next, an operation when downlink traffic occurs for LL-STA 30-3 that has entered the standby state will be described. Fig. 8 is a diagram showing an example of an operation when downlink traffic occurs for LL-STA 30-3 that has entered the standby state.

[0066] When downlink traffic to LL-STA 30-3 occurs, the first AP 10-3 instructs LL-STA 30-3 via the second AP 20-3 to switch the frequency of the RF unit 34 to the frequency of the RF unit 14. In this case, LL-STA 30-3 switches the frequency of the RF unit 34 to the frequency of the RF unit 14.

[0067] The first AP 10-3 transmits a downlink packet to the LL-STA 30-3 using the frequency of the RF unit 14.

[0068] Next, an operation when the LL-STA 30-3 that has entered the standby state wishes to transmit an uplink packet will be described. Fig. 9 is a diagram showing an example of the operation when the LL-STA that has entered the standby state wishes to transmit an uplink packet.

[0069] When uplink traffic to be transmitted occurs, the LL-STA 30-3 transmits an access request to the first AP 10-3 via the second AP 20-3. At the same time, the LL-STA 30-3 switches the frequency of the RF unit 34 from the frequency of the RF unit 24 to the frequency of the RF unit 14.

[0070] When the first AP 10-3 grants its TXOP to the LL-STA 30-3, the LL-STA 30-3 transmits an uplink packet to the first AP 10-3.

[0071] [When there is no RF unit dedicated to access transfer and MLO is used] Next, the operation of the wireless communication system will be described using an example where the LL-STA does not have an RF unit dedicated to access transfer and MLO is used. Figure 10 is a diagram showing an example of the operation of the wireless communication system using an example where the LL-STA does not have an RF unit dedicated to access transfer and MLO is used.

[0072] The first AP 10-4 has, for example, two RF units 16a and 16b. The second AP 20-4 has, for example, two RF units 26a and 26b. The LL-STA 30-4 has, for example, two RF units 36a and 36b. In the initial state, the frequencies of the RF units 16a and 16b of the first AP 10-1, which is the communication destination AP, are assumed to be the same as the frequencies of the RF units 36b and 36a of the LL-STA 30-1, respectively.

[0073] For example, if it is difficult for the LL-STA 30-4 to obtain access rights to the first AP 10-4 and easy to obtain access rights to the second AP 20-4, the LL-STA 30-4 switches the frequency of the RF unit 36a to the frequency of the RF unit 26a and associates with the second AP 20-4 while maintaining the association with the first AP 10-4.

[0074] Then, the LL-STA 30-4 notifies the first AP 10-4 via the second AP 20-4 that the frequency of the RF unit 36a has been switched to the frequency of the RF unit 26a. Thus, the first AP 10-4 recognizes that the LL-STA 30-4 has entered a standby state using the frequency of the RF unit 26a.

[0075] Next, an operation when downlink traffic occurs for LL-STA 30-4 that has entered the standby state will be described. Fig. 11 is a diagram showing an example of an operation when downlink traffic occurs for LL-STA that has entered the standby state.

[0076] If the first AP 10-4 can obtain access rights at the frequency of the RF unit 16a, the LL-STA 30-4 transmits downlink traffic at that frequency.

[0077] Next, a case where the first AP 10-4 can obtain access rights at the frequency of the RF unit 16b will be described. Fig. 12 is a diagram showing an example of operation when downlink traffic occurs for an LL-STA that has entered a standby state.

[0078] In this case, the first AP 10-4 notifies the LL-STA 30-4 to change the frequency of the RF unit 36a to the frequency of the RF unit 16b. Then, the LL-STA 30-4 performs communication using the frequency of the RF unit 16b. In other words, the first AP 10-4 transmits a downlink packet to the LL-STA 30-4 using the frequency of the RF unit 16b.

[0079] Next, an operation when uplink traffic occurs in LL-STA 30-4 that has entered the standby state will be described. Fig. 13 is a diagram showing an example of an operation when uplink traffic occurs in LL-STA 30-4 that has entered the standby state.

[0080] The LL-STA 30-4 notifies the first AP 10-4 of the request information via the second AP 20-4. If the first AP 10-4 has a TXOP at the frequency of the RF unit 16a, it cede the TXOP. Then, the LL-STA 30-4 transmits an uplink packet to the first AP 10-4.

[0081] FIG. 14 is a diagram showing an example of operation when the first AP 10-4 has a TXOP at the frequency of the RF unit 16b. When the first AP 10-4 has a TXOP at the frequency of the RF unit 16b, it operates as shown in FIG. 14. The LL-STA 30-4 notifies the first AP 10-4 of request information via the second AP 20-4. The first AP 10-4 instructs the LL-STA 30-4 via the second AP 20-4 to switch the frequency to the frequency of the RF unit 16b. The LL-STA 30-4 switches the frequency to the RF unit 16b. Then, when the first AP 10-4 cedes the TXOP of the frequency of the RF unit 16b that it has to the LL-STA 30-4, the LL-STA 30-4 transmits an uplink packet to the first AP 10-4.

[0082] [Concession Method] The operation when the first AP 10-5 cedes a TXOP will be described below. Fig. 15 is a diagram showing an example of the operation when the first AP 10-5 cedes a TXOP.

[0083] The LL-STA 30-5 transmits the request information to the first AP 10-5 via the second AP 20-5. If the first AP 10-5 owns the TXOP, it transmits a trigger frame to the LL-STA 30-5, notifying it of the TXOP surrender. The LL-STA 30-5 transmits an uplink packet to the first AP 10-5.

[0084] Next, the effects of each of the above-mentioned wireless communication systems will be described. Figures 16 and 17 each show a case where an uplink packet from LL-STA 30 or the like occurs during a TXOP period of the first AP 10 or the like. In Figures 16 and 17, (a) shows the delay time of the conventional technology, and (b) shows the delay time of the wireless communication system according to one embodiment. In Figure 16, the white parts indicate the time when other STAs are transmitting.

[0085] In the prior art, the LL-STA must wait for at least the completion of the AP's downlink traffic transmission before transmitting a packet. If another STA obtains access rights after the AP's downlink traffic transmission is completed, the LL-STA must wait until the other STA completes its communication.

[0086] In contrast, in one embodiment of the wireless communication system, when the LL-STA 30 or the like notifies the first AP 10 or the like of request information, the first AP 10 or the like stops transmitting the downlink traffic it is communicating and transfers the TXOP it holds to the LL-STA 30 or the like, so that the LL-STA 30 or the like can transmit uplink packets with a short delay time.

[0087] 18 is a diagram illustrating a case where a medium such as the first AP 10 is busy because it is occupied by another STA, in which (a) shows the delay time of the conventional technology, and (b) shows the delay time of the wireless communication system according to one embodiment.

[0088] LL-STA30 and the like must wait until the uplink communication of the other STA is completed, but if the first AP10 and the like can obtain access rights and set a TXOP immediately after the communication of the other STA is completed, LL-STA30 can shorten the delay time by having the TXOP ceded to it by the first AP10.

[0089] Note that when the medium is idle, if there is no collision with other stations when obtaining access rights, the delay time of the LL-STA in the conventional technology and the delay time of the LL-STA 30 or the like in the wireless communication system according to one embodiment are the same. Figure 19 is a diagram showing the delay time of the LL-STA in the conventional technology and the delay time of the LL-STA 30 or the like in the wireless communication system according to one embodiment. In Figure 19, (a) shows the delay time of the conventional technology, and (b) shows the delay time of the wireless communication system according to one embodiment. Furthermore, when the LL-STA 30 transmits request information to the second AP 20, it is also possible for the LL-STA 30 to transmit an uplink packet using the medium of the second AP 20.

[0090] In this way, a wireless communication system 100 according to one embodiment transmits request information to the first AP 10 via the second AP 20, so that when there is a mixture of terminals that require low latency and terminals that do not require low latency, the delay time of terminals that require low latency can be reduced.

[0091] In addition, each function possessed by the first AP 10, the second AP 20, and the LL-STA 30 may be partially or entirely configured by hardware such as a PLD (Programmable Logic Device) or an FPGA (Field Programmable Gate Array), or may be configured as a program executed by a processor such as a CPU.

[0092] For example, the second AP 20 can be realized using a computer and a program, and the program can be recorded on a storage medium or provided via a network.

[0093] 20 is a diagram illustrating an example of a hardware configuration of the second AP 20 according to an embodiment. As illustrated in FIG. 20, the second AP 20 has an input unit 50, an output unit 51, a communication unit 52, a CPU 53, a memory 54, and an HDD 55 connected via a bus 56, and functions as a computer. The second AP 20 is also configured to input and output data to and from a computer-readable storage medium 57.

[0094] The input unit 50 is, for example, a keyboard and a mouse. The output unit 51 is, for example, a display device such as a display that outputs images. The communication unit 52 is, for example, a wired or wireless network interface, and may have a function as an output unit that outputs data to the outside.

[0095] As described above, the CPU 53 controls the components of the second AP 20 and performs predetermined processing, etc. The memory 54 and the HDD 55 are storage units that store data, etc.

[0096] The storage medium 57 is capable of storing programs and the like that cause the second AP 20 to execute the functions of the second AP 20. Note that the architecture that constitutes the second AP 20 is not limited to the example shown in FIG.

[0097] The functions performed by the components described herein may be implemented in circuitry or processing circuitry, including general purpose processors, application specific processors, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (a Central Processing Unit), conventional circuits, and / or combinations thereof, programmed to perform the described functions.

[0098] A processor includes transistors and other circuits and is considered to be circuitry or processing circuitry. A processor may be a programmed processor that executes programs stored in memory.

[0099] In this specification, a circuitry, unit, or means is hardware that is programmed to realize or performs the described functions, which may be any hardware disclosed herein or any hardware known to be programmed to realize or perform the described functions.

[0100] If the hardware is a processor considered to be a type of circuitry, the circuitry, means, or unit is a combination of the hardware and software used to configure the hardware and / or processor.

[0101] 10, 10-1 to 10-5... 1st AP, 12a to 12c, 14, 14a to 14c, 16a to 16c, 18a to 18c, 22a to 12c, 24, 24a to 24c, 26a to 26c, 28a to 28c, 32a to 32d, 34, 34a to 34b, 36a to 36b, 38a to 38b...RF section, 20, 20-1 to 20 -5... 2nd AP, 30, 30-1 to 30-5... LL-STA, 40... STA, 50... input unit, 51... output unit, 52... communication unit, 53... CPU, 54... memory, 55... HDD, 56... bus, 57... storage medium, 100, 100a, 100b, 100c... wireless communication system

Claims

1. A wireless communication system comprising a destination access point, an access point for transmitting access, a low-delay request terminal that transmits packets requiring a specified low delay, and a non-low-delay request terminal that is tolerant of transmitting packets with a longer delay time than the low-delay request terminal, wherein when the access transmission access point receives request information from the low-delay request terminal indicating an access request to the destination access point, the access transmission access point transmits the request information to the destination access point, and the destination access point grants a TXOP to the low-delay request terminal.

2. The wireless communication system described in claim 1, characterized in that the low-latency request terminal is equipped with a dedicated RF unit for transmitting the request information, and the destination access point, the access point for access transmission, and the low-latency request terminal perform single-link operation or multi-link operation.

3. A wireless communication method performed by a wireless communication system comprising a destination access point, an access point for transmitting access, a low-delay request terminal that transmits packets requiring a specified low delay, and a non-low-delay request terminal that is tolerant of transmitting packets with a longer delay time than the low-delay request terminal, wherein when the access transmission access point receives request information from the low-delay request terminal indicating an access request to the destination access point, the access point transmits the request information to the destination access point, and the destination access point grants a TXOP to the low-delay request terminal.

4. The wireless communication method described in claim 3, characterized in that the low-latency requesting terminal is equipped with a dedicated RF unit for transmitting the request information, and the destination access point, the access point for transmitting access, and the low-latency requesting terminal perform single-link operation or multi-link operation.

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