JP6069144B2 - Wireless communication system and wireless communication method - Google Patents

Description

  The present invention relates to a communication technique between a radio base station apparatus, a signal processing apparatus, and a radio terminal.

  2. Description of the Related Art Conventionally, a technique has been proposed in which wireless signal processing to be executed by an access point (AP) is executed by a general-purpose signal processing device arranged on a network. With such a technique, it is possible to accommodate a plurality of radio systems with one radio base station apparatus. In addition, it is possible to achieve downsizing, cost reduction, and long life by simplifying the access point and making it single function.

  In the signal processing device, radio signal processing is executed by either hardware or software. By realizing wireless signal processing by software, it becomes possible to respond more flexibly when supporting a new wireless system.

  In the technique described in Patent Document 1, wireless signal processing is executed in an access point or a signal processing device. Whether the access point or the signal processing device executes the signal processing is determined by the type of the wireless system used. When the wireless method used is a wireless method that can be executed at the access point, the access point performs wireless signal processing. On the other hand, when the wireless method used is a wireless method that is not executable at the access point, the signal processing device performs wireless signal processing. Even when the wireless signal processing at the access point is not in time for the response time regulation required by the wireless system, the signal processing device performs the wireless signal processing.

  In order to perform wireless signal processing in a signal processing device connected to the network side, a data transfer delay of an order of milliseconds or more generally occurs between the access point and the signal processing device. Therefore, it is impossible to accommodate a wireless system whose response time is defined in the microsecond order as in a wireless LAN (Local Area Network) defined by IEEE 802.11. Further, if the response time rule is simply relaxed, the time required to transmit one packet increases due to a transmission delay, and the throughput decreases. That is, since the communication path is wide but the delay is large, the end-end throughput is reduced. Such a problem is sometimes called a “Long Fat Pipe problem”.

  In order to solve such a problem, a wireless protocol capable of realizing a high throughput even when a round trip delay exists is required. As one of the solutions, there are a sliding window technique in wired communication (see Non-Patent Document 1) and a proxy response technique (see Non-Patent Document 2) used in satellite communication with a large round trip delay.

The technique described in Non-Patent Document 1 will be described with reference to FIG. FIG. 8 is a diagram showing an outline of the technique disclosed in Non-Patent Document 1. FIG. 8A is a diagram showing an outline of a protocol for transmitting ACK for each packet. FIG. 8B is a diagram showing an outline of the sliding window technique when the window size is four. As shown in FIG. 8A, in the protocol that requires an acknowledgment (ACK) for each packet, the next packet cannot be transmitted until the ACK is returned. For this reason, the throughput decreases when the transmission delay time is long. On the other hand, as shown in FIG. 8B, in a technique (sliding window technique) that enables a packet to be transmitted even if an ACK is not returned up to a specified window size, the throughput between end and end is reduced. Can be improved. The throughput (theoretical upper limit) in the sliding window technique is given by the following equation. FIG. 8B shows a specific example of processing when the window size is 4.
Throughput [MByte] = Window size [KByte] / Round-trip delay time [ms]

  FIG. 9 is a diagram showing an outline of the technique disclosed in Non-Patent Document 2. In the technology described in Non-Patent Document 2, in a broadcast / multicast communication system using a satellite, the round trip delay between end and end (between the server and the user PC) reaches several hundred ms. However, the gateway installed in the center station terminates the protocol by returning an acknowledgment (ACK) to the server instead of the user PC. Therefore, the throughput can be improved by continuously transmitting the satellite section. Even if a packet error occurs in the radio section and retransmission is necessary, the center station can cope with the packet error by sending a retransmission packet. Therefore, good communication quality can be realized.

  In a wireless LAN (IEEE 802.11), which is a typical example of high-speed wireless communication, a protocol is designed based on delivery confirmation for each packet. Block ACK has been standardized as a technique for improving throughput in a wireless LAN by reducing the overhead of delivery confirmation (see Non-Patent Document 3). In block ACK, a plurality of packets are continuously transmitted, and ACK is returned collectively. Through such processing, overhead required for data delivery confirmation is reduced, and throughput is improved.

  FIG. 10 is a diagram illustrating a specific example of a communication sequence using a block ACK. FIG. 10 shows a specific example of processing when the window size is 4. FIG. 10A is a diagram showing an outline of immediate block ACK processing. FIG. 10B is a diagram showing an outline of the delay block ACK process. As shown in FIG. 10A, in the immediate block ACK, the block ACK is immediately returned. Further, as shown in FIG. 10B, in the delayed block ACK, the block ACK is returned with a delay after the data transmission is completed. Note that a block ACK request packet (Block ACK Request: BAR) for requesting transmission of a block ACK after completion of data transmission may or may not be used.

  In Non-Patent Document 4, a long NAV (Network Allocation Vector: virtual carrier sense) period described in the Duration field of the CTS transmitted by the access point in the RTS / CTS procedure is set without changing the terminal protocol. Thus, there is disclosed a technique for preventing collision of ACK packets caused by transmission delay only by a change on the access point side. This technique can improve the throughput.

  FIG. 11 is a diagram showing an outline of the technique disclosed in Non-Patent Document 4. In the operation of the IEEE 802.11 standard, when the RTS / CTS procedure is used between the terminal 1 and the access point, the terminal 2 is prohibited from transmitting by the NAV function. However, when the transmission delay exceeds the DIFS period (34 μs), the packet transmitted by the terminal 2 collides with the ACK packet transmitted by the access point.

  On the other hand, in the technique disclosed in Non-Patent Document 4, a period considering transmission delay is set in the NAV period of the CTS packet transmitted by the access point. Therefore, collision of ACK packets can be avoided.

JP 2009-231903 A

“Mastering TCP / IP Introduction”, Takashi Takeshita, Koho Murayama, Toru Arai, Yukio Hirota, Ohmsha, 2nd edition, published on May 25, 1998, p.184-186 "A Satellite Communication System for Interactive Multimedia Networks", Masayoshi Nakayama, Manabu Nakagawa, Youichi Hashimoto, Kazunori Tanaka, Hiroshi Nakashima, IEICE Transactions on Communications, vol.E80-B, No.1, January 1997, pp.103 -108 "IEEE802.11-2012 standard specification, pp.907" "Throughput improvement method by AP of wireless LAN system using RoF", Masamasa Okamoto, Yuki Sangenya, Masahiro Morikura, Takashi Yamamoto, Fusao, IEICE technical report, RCS2012-300, Heisei Published February 25, p.97-102

  In the proxy response technique described in Non-Patent Document 2, an ACK is returned to the server after it is confirmed that there is no error in the packet at the gateway that executes the proxy response. In order to apply such a technique to a wireless access point, it is necessary to execute demodulation processing of the wireless packet in real time at the access point. Therefore, it is necessary to mount sufficient signal processing capability on the access point, and the access point cannot be mounted with a simple configuration.

  FIG. 12 is a diagram illustrating a problem of immediate block ACK processing. In the technique of immediate block ACK, transmission of other terminals is suppressed by the effect of NAV during the period from the completion of terminal BAR packet transmission to the return of block ACK by the access point. For this reason, when the transfer delay between the access point and the signal processing apparatus is large, one terminal that is transmitting data continues to occupy the radio resource, so that no communication is performed (hereinafter referred to as “no communication”). Period ”). Therefore, there arises a problem that the wireless usage efficiency is lowered.

  On the other hand, in the case of a delayed block ACK, the NAV is canceled after the transmission of the BAR packet. For this reason, other terminals can use radio resources. However, the period from when the block ACK is transmitted until the ACK response is returned is a no-communication period. Therefore, similarly to the immediate block ACK, a non-communication period corresponding to the network round-trip transmission time occurs.

  In addition, in the delayed block ACK, the block ACK is transmitted after the channel access right is acquired by random backoff as in the case of the normal packet. Therefore, transmission cannot always be performed at the fastest timing, and a delivery confirmation delay occurs.

When block ACK is used, a plurality of data packets are continuously transmitted with priority given to throughput improvement. Therefore, the occupation time of one terminal becomes long, and the above-mentioned delivery confirmation delay becomes apparent particularly when the traffic is large.
In order to achieve the desired throughput, the data size of continuous transmission is set large in advance in consideration of the above-described delivery confirmation delay. In this case, there arises a problem that the size of the buffer arranged in the transceiver increases.

  In addition, the technique disclosed in Non-Patent Document 4 can certainly avoid packet collision that occurs due to transmission delay. However, the technique disclosed in Non-Patent Document 4 cannot suppress a decrease in throughput due to the “Long Fat Pipe problem” caused by transmission delay.

  In view of the above circumstances, an object of the present invention is to provide a wireless communication technique capable of realizing high throughput while relaxing response time regulations.

  One aspect of the present invention is a wireless communication system including an access point (AP) that wirelessly communicates with a wireless terminal, and a signal processing device that performs signal processing on a wireless signal received by the access point, A communication control unit is provided that transmits one delivery confirmation for a plurality of packets transmitted from the wireless terminal during a preferential transmission period provided periodically.

  One aspect of the present invention is the above wireless communication system, wherein the communication control unit uses a CFP (Contention Free Period) of a PCF (Point Coordination Function) as the priority transmission period, and the delivery confirmation is performed in a polling packet. Include.

  One aspect of the present invention is the above wireless communication system, wherein the communication control unit periodically transmits the delivery confirmation at a high-priority packet interval for one or a plurality of packets as the priority transmission period. To do.

  One aspect of the present invention is the above wireless communication system, wherein the wireless terminal transmits the plurality of packets using a first transfer type identifier, and then performs the delivery confirmation regarding the first transfer type identifier. Are received using the second transfer type identifier before the packet is received.

  One aspect of the present invention is a wireless communication method performed by a wireless communication system that includes an access point that performs wireless communication with a wireless terminal and a signal processing device that performs signal processing on a wireless signal received by the access point. And a communication control step of transmitting one delivery confirmation for a plurality of packets transmitted from the wireless terminal during a predetermined priority transmission period.

  One aspect of the present invention is the above wireless communication method, wherein, in the communication control step, a CFP (Contention Free Period) of PCF (Point Coordination Function) is used as the priority transmission period, and the delivery confirmation is performed in a polling packet. Include.

  One aspect of the present invention is the above-described wireless communication method, wherein in the communication control step, the delivery confirmation is transmitted at a high-priority packet interval for one or a plurality of packets periodically as the priority transmission period. To do.

  One aspect of the present invention is the wireless communication method described above, wherein the wireless terminal transmits the plurality of packets using a first transfer type identifier, and then performs the delivery confirmation regarding the first transfer type identifier. Are received using the second transfer type identifier before the packet is received.

  According to the present invention, it is possible to achieve high throughput while relaxing response time regulations.

It is a figure which shows the outline of the process in the radio | wireless communications system of this invention. It is a figure which shows the structure of each apparatus relevant to the radio | wireless communications system of this invention. It is a figure which shows the communication sequence of an uplink. It is a figure which shows the communication sequence of a downlink. It is a flowchart which shows operation | movement of the access point 20 in an uplink. 4 is a flowchart showing an operation of the radio terminal 10 in the uplink. It is a figure which shows the example of a communication sequence when resending generate | occur | produces in an uplink. It is a figure which shows the outline of the technique disclosed by the nonpatent literature 1. FIG. It is a figure which shows the outline of the technique disclosed by the nonpatent literature 2. FIG. It is a figure which shows the specific example of the communication sequence using block ACK. It is a figure which shows the outline of the technique disclosed by the nonpatent literature 4. FIG. It is a figure which shows the problem of the process of immediate block ACK.

[Outline]
FIG. 1 is a diagram showing an outline of processing in the wireless communication system of the present invention. In the wireless communication system of the present invention, the wireless terminal can continuously transmit a plurality of packets without waiting for an ACK response according to the window size. That is, the access point returns one ACK for a plurality of packets transmitted from the wireless terminal. In addition, the access point transmits ACK within the AP priority transmission period provided periodically. As shown in FIG. 1, the AP priority period is provided, for example, as a period from when the access point transmits a CFP notification beacon until a centralized control period end notification is transmitted. With this configuration, it is possible to suppress a decrease in throughput due to network transfer delay.

  Further, in the wireless communication system of the present invention, the NAV period set for the wireless terminal is shortened compared to the conventional case. For this reason, it is possible to provide more timings at which other wireless terminals can use the wireless resources.

[Details]
Next, details of the wireless communication system of the present invention will be described. FIG. 2 is a diagram showing a configuration of each device related to the wireless communication system of the present invention. A plurality of wireless terminals 10 (10-1 to 10-3) are connected to the access point 20. Each wireless terminal 10 performs wireless communication with the access point 20. Each wireless terminal 10 performs data communication with a communication device (not shown) connected to the network 30 via the access point 20. The wireless terminal 10 and the access point 20 are installed in the user's home, for example. The access point 20 and the signal processing device 40 cooperate to perform modulation processing and demodulation processing of the radio signal. The association between the access point 20 and the signal processing device 40 may be performed, for example, by a wireless method management device (not shown).

The access point 20 includes a wireless communication unit 201, a communication control unit 202, and an upper communication unit 203. The wireless communication unit 201 performs wireless communication with one or a plurality of wireless terminals 10. The communication control unit 202 controls communication in the wireless communication unit 201 and the upper communication unit 203. The upper communication unit 203 communicates via the network 30. The higher-level communication unit 203 communicates with, for example, the signal processing device 40 and a communication device (not illustrated) that is a communication partner of the wireless terminal 10.
The signal processing device 40 includes a communication unit 401 and a communication control unit 402. The communication unit 401 communicates with the access point 20 via the network 30. The communication control unit 402 controls communication in the communication unit 401. When the signal processing device 40 performs signal processing, the signal processing device 40 performs signal processing instead of the access point 20.

  FIG. 3 is a diagram illustrating an uplink communication sequence. In FIG. 3, time flows from top to bottom. FIG. 3 shows the flow of processing when signal processing is performed by the signal processing device 40. Therefore, in FIG. 3, the packet transmitted from the wireless terminal 10 is relayed to the signal processing device 40 by the access point 20, and the signal processing device 40 performs signal processing on behalf of the access point 20. Note that, when communication is performed in a wireless manner that can be processed by the access point 20, processing by the signal processing device 40 illustrated in FIG. 3 is executed by the access point 20. The same applies to FIGS. 4 and 7.

First, block ACK preliminary preparation processing is performed. In the block ACK preliminary preparation process, the wireless terminal 10-1 (TID = 1) transmits a BA (block ACK) setting request. The BA setting request is transmitted to the signal processing device 40 via the access point 20.
The signal processing device 40 sequentially transmits a beacon (CFP (Contention Free Period) notification), a polling packet (ACK), and a centralized control period end notification. Each signal is transmitted to a plurality of wireless terminals (10-1 to 10-3) via the access point 20. Thereafter, the signal processing device 40 transmits a BA (block ACK) setting response to the wireless terminal 10-1 via the access point 20. The wireless terminal 10-1 transmits an ACK to the BA setting request to the signal processing device 40. In addition, after the wireless terminal 10-1 transmits the BA setting request until the beacon transmitted by the signal processing device 40 is relayed by the access point 20, another wireless terminal 10 (for example, 10-2 or 10) 10-3) can communicate wirelessly. On the other hand, when the beacon (CFP notification) is relayed by the access point 20, the AP preferential transmission period is started. The polling packet (ACK) transmitted by the signal processing device 40 and the centralized control period end notification are relayed by the access point 20 during the AP priority transmission period.

  Next, data transmission processing is performed. In the data transmission process, the wireless terminal 10-1 continuously transmits a plurality of data packets (data packets A to D) at SIFS (Short InterFrame Space) intervals. Then, the radio terminal 10-1 transmits a BAR (Block ACK request packet) to the signal processing device 40.

  The signal processing device 40 sequentially transmits a beacon (CFP notification), a polling packet (block ACK), and a central control period end notification. Each signal is transmitted to a plurality of wireless terminals (10-1 to 10-3) via the access point 20. In addition, after the wireless terminal 10-1 transmits the BAR until the beacon transmitted by the signal processing device 40 is relayed by the access point 20, another wireless terminal 10 (for example, 10-2 or 10-) 3) can communicate wirelessly.

Next, end processing is performed. In the termination process, the wireless terminal 10-1 transmits a BA (block ACK) setting release notification to the signal processing device 40.
The signal processing device 40 sequentially transmits a beacon (CFP notification), a polling packet (ACK), and a central control period end notification. Each signal is transmitted to a plurality of wireless terminals (10-1 to 10-3) via the access point 20. In addition, after the wireless terminal 10-1 transmits the BA setting release notification until the beacon transmitted by the signal processing device 40 is relayed by the access point 20, another wireless terminal 10 (for example, 10-2) Or 10-3) can perform wireless communication.

  As shown in FIG. 3, the radio terminal 10 continuously transmits data packets at SIFS intervals. The access point 20 transmits delivery confirmation of a plurality of data packets as one block ACK. The access point 20 transmits a block ACK during the AP priority transmission period that is set periodically. By such processing, even after the wireless terminal 10 (for example, 10-1) transmits the BA setting request, the data packet, or the BA setting release notification, the signal processing device 40 Until the beacon (CFP notification) is transmitted, the other wireless terminal 10 can use the wireless resource. Therefore, it is possible to improve the utilization efficiency of radio resources. Further, the wireless terminal 10 can continuously transmit data packets without waiting for an ACK return. Then, delivery confirmation is performed by returning one block ACK for a plurality of data packets transmitted continuously. Therefore, it is possible to suppress a decrease in throughput due to network transmission delay.

  Similar to the block ACK described in Non-Patent Document 3, a block ACK setting process is performed in advance between the wireless terminal 10 and the access point 20 for each TID (Transmission ID: transfer type ID). In the block ACK setting process, various pieces of information regarding block ACK are set by exchanging a block ACK setting request and a block ACK setting response. The same applies to the end processing.

  In order to realize block ACK preferential transmission, a DCF (Distributed Coordination Function) and a PCF (Point Coordination Function) are used together as an access control method. Thereby, the CFP in which the access point 20 manages the transmission right is periodically provided as the ACK priority transmission period. For this reason, the access point 20 periodically transmits a part of the beacon as a “beacon for CFP notification”. The block ACK is not transmitted as an independent packet but is embedded in a payload of a polling packet transmitted from the access point 20 and transmitted.

  For the block ACK and the block ACK request packet, the access point 20 and the wireless terminal 10 perform retransmission control by timeout. That is, the access point 20 and the wireless terminal 10 do not individually return an ACK response to the block ACK and the block ACK request packet. For this reason, it is possible to suppress a decrease in throughput due to a delivery confirmation delay. Note that the block ACK timeout allowable time may be extended corresponding to the network delay so as not to time out due to the transmission delay of the network. If the response time regulation (SIFS in the wireless LAN) itself is extended, the packet transmission interval set based on SIFS is widened, which may reduce the throughput. However, in the wireless communication system of the present invention, the response time rule is not changed. Therefore, it is possible to prevent the packet transmission interval from extending.

  FIG. 4 is a diagram illustrating a downlink communication sequence. In FIG. 4, time flows from top to bottom. First, the signal processing device 40 continuously transmits a plurality of data packets (data packets A2 to D2 addressed to the wireless terminal 10-1) received from the communication device via the network to the wireless terminal 10-1. At this time, the signal processing device 40 transmits data packets at SIFS intervals.

  The wireless terminal 10-1 transmits a block ACK after receiving a plurality of data packets. The block ACK transmitted by the wireless terminal 10-1 is relayed to the signal processing device by the access point 20.

  When receiving the block ACK, the signal processing device 40 continuously receives the next plurality of data packets (data packets E2 to H2 addressed to the wireless terminal 10-1) received from the communication device via the network. Send to.

  The process performed by the wireless terminal 10 is the same process as the block ACK (immediate block ACK) described in Non-Patent Document 3. Similar to the processing of the radio terminal 10 in the uplink, the timer value provided for the timeout management of the block ACK in the signal processing device 40 is extended corresponding to the network delay.

FIG. 5 is a flowchart showing operations of the access point 20 and the signal processing device 40 in the uplink. Hereinafter, the flowchart of FIG. 5 will be described as the processing of the access point 20.
The access point 20 repeatedly receives data packets until all data packets are received (steps S101 and S102—NO). When the access point 20 receives the BAR packet (YES in step S102), the access point 20 determines that all the data packets have been received, generates a block ACK packet by converting the presence / absence of an error in each data packet into a bitmap (step S103). ). Then, the access point 20 waits until beacon (CFP notification) transmission timing, which is a block ACK priority transmission period (step S104—NO).

  When it is beacon transmission timing and it is not the AP priority transmission period (step 104-YES, step S105-NO), the access point 20 transmits a normal beacon after DIFS and backoff (step S106). . Thereafter, the access point 20 returns to the process of step S104 and waits until the next beacon transmission timing.

  On the other hand, when it is the beacon transmission timing and the AP priority transmission period (step 104-YES, step S105-YES), the access point 20 uses a PIFS (Point Inter-Frame Space) interval used during centralized control. To send a CFP notification beacon. Thereafter, the access point 20 transmits a polling packet to the wireless terminal 10 at SIFS intervals (step S107). The payload of the polling packet includes a block ACK.

  Thereafter, the access point 20 transmits a centralized control period end notification at SIFS intervals (step S108). Then, the access point 20 starts timing by the BAR retransmission wait timer (step S109). Then, the access point 20 waits for reception of a retransmission BAR until the BAR retransmission wait timer ends (steps S110-NO and S111-NO). If the access point 20 receives a retransmission BAR from the wireless terminal 10 before the BAR retransmission wait timer expires (step S110-YES), the access point 20 returns to the process of step S104. On the other hand, when the BAR retransmission waiting timer ends without receiving a retransmission BAR from the wireless terminal 10 (step S111—YES), the access point 20 ends the packet reception process. This is the end of the process shown in FIG.

  PIFS is defined shortly after SIFS. PIFS is shorter than DIFS (Distributed Inter-Frame Space), which is a packet interval used in normal packet transmission in DCF. Therefore, it becomes possible to transmit a beacon (CFP notification) with priority over a normal packet. When the access point 20 transmits the CFP notification beacon, the access point 20 can manage the transmission right thereafter. On the other hand, the wireless terminal 10 cannot transmit unless a transmission opportunity is given by polling. Therefore, the priority transmission period of the access point 20 can be realized.

After transmitting the polling packet, the access point 20 returns to the normal distributed control access control (DCF) by transmitting a central control period end notification at SIFS intervals. Thereby, it is possible to suppress occurrence of unnecessary no communication time.
In the process of FIG. 5, a block ACK setting process is performed between the wireless terminal 10 and the access point 20 in advance for each TID. Further, the transmission cycle of the notification beacon of CFP (AP priority transmission period) may be set as an integral multiple of the transmission cycle of the normal beacon (once every N times: N is an integer of 2 or more). In addition, after the packet reception process ends, a block ACK end process is performed for each TID.
Further, when realizing the AP priority transmission period, the method of using the PCF described above is simplified, and the access point 20 transmits a block ACK packet at a high-priority packet interval such as PIFS at a periodic timing. By doing so, it is possible to achieve the purpose. In this case, the access point 20 does not transmit a beacon (CFP notification), a polling packet, or a centralized control period end notification, and transmits one or a plurality of block ACKs at PIFS intervals.

  FIG. 6 is a flowchart showing the operation of the radio terminal 10 in the uplink. The wireless terminal 10 repeatedly transmits data packets at SIFS intervals until all data packets are transmitted (steps S201 and S202—NO). When transmitting all the data packets (YES in step S202), the wireless terminal 10 transmits a block ACK request (BAR) packet (step S203).

  After transmitting the data packet and the BAR packet, the wireless terminal 10 starts timing by the block ACK waiting timer (step S204). Then, the radio terminal 10 waits for reception of a block ACK until the block ACK waiting timer expires (steps s205-NO, S206-NO). If the wireless terminal 10 receives a block ACK before the block ACK waiting timer expires (step S205—YES), the wireless terminal 10 ends the packet transmission process. On the other hand, when the block ACK waiting timer ends without receiving the block ACK (steps S205-NO and S206-YES), the wireless terminal 10 determines that the block ACK has not been received normally. In this case, the radio terminal 10 requests the access point 20 to retransmit the block ACK by retransmitting the BAR (step S207).

  The wireless terminal 10 determines the presence or absence of an error packet based on the presence or absence of an error in each data packet described in the received block ACK bitmap. Then, only the error packet is retransmitted at the next packet transmission timing. Therefore, efficient packet transmission can be realized.

  In the process of FIG. 6, a block ACK setting process is performed between the wireless terminal 10 and the access point 20 in advance for each TID. Further, after the packet transmission process is completed, a block ACK termination process is performed for each TID.

  FIG. 7 is a diagram showing an example of a communication sequence when retransmission occurs in the uplink. In FIG. 7, time flows from top to bottom. The block ACK preliminary preparation process and the end process are the same as the processes shown in FIG.

  In the specific example of FIG. 7, first, data A1 to D1 are transmitted between the wireless terminal 10 and the access point 20 using TID = 1. Thereafter, when the wireless terminal 10 cannot receive the polling packet (block ACK) transmitted by the signal processing device 40, the wireless terminal 10 retransmits the BAR due to the timeout of the block ACK waiting timer. Thereafter, the wireless terminal 10 transmits the data E1 to H1 using TID = 2 without waiting for the reception of the block ACK for the data A1 to D1. Further, the wireless terminal 10 transmits a BAR related to the data E1 to H1. Note that the data E1 to H1 are different from the data A1 to D1, and are data following the data A1 to D1, for example.

  Thereafter, the signal processing device 40 transmits a block ACK for the data A1 to D1 for which retransmission is requested and a block ACK for the newly transmitted data E1 to H1.

  On the other hand, in the wireless communication system described above, by using a plurality of TIDs in one wireless terminal 10, data is newly transmitted before the block ACK is received. Therefore, it is possible to suppress a decrease in throughput when resending the block ACK. That is, when the block ACK with TID = 1 is not returned within the specified time, the wireless terminal 10 retransmits the BAR with TID = 1, and further transmits the subsequent data E1 to H1 using TID = 2. Through such processing, it is possible to maintain a throughput that is almost equivalent to the case where retransmission is not performed.

<Modification>
You may make it implement | achieve the radio | wireless terminal 10, the access point 20, or the signal processing apparatus 40 in embodiment mentioned above with a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program held for a certain period of time. Further, the program may be a program for realizing a part of the above-described functions, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system. You may implement | achieve using programmable logic devices, such as FPGA (Field Programmable Gate Array).
The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 (10-1-10-3) ... Wireless terminal, 20 ... Access point, 201 ... Wireless communication part, 202 ... Communication control part, 203 ... High order communication part, 30 ... Network, 40 ... Signal processing apparatus, 401 ... Communication , 402 ..Communication control unit

Claims (6)

A wireless communication system comprising: an access point that wirelessly communicates with a wireless terminal; and a signal processing device that performs signal processing on a wireless signal received from the wireless terminal and relayed by the access point,
One delivery confirmation is made for a plurality of packets transmitted from the wireless terminal in a priority transmission period that is a period from when the access point transmits a CFP notification beacon until a centralized control period end notification is transmitted. A wireless communication system including a communication control unit that performs control to relay the access point from the signal processing device and transmit the relayed access point to the wireless terminal .   The wireless communication system according to claim 1, wherein the communication control unit uses a CFP (Contention Free Period) of a PCF (Point Coordination Function) as the priority transmission period and includes the delivery confirmation in a polling packet. The wireless terminal uses the second transfer type identifier after transmitting the plurality of packets using the first transfer type identifier and before receiving the delivery confirmation regarding the first transfer type identifier. transmitting a plurality of other packets, a wireless communication system according to claim 1 or 2. A wireless communication method performed by a wireless communication system comprising: an access point that wirelessly communicates with a wireless terminal; and a signal processing device that performs signal processing on a wireless signal received from the wireless terminal and relayed by the access point. ,
One delivery confirmation is made for a plurality of packets transmitted from the wireless terminal in a priority transmission period that is a period from when the access point transmits a CFP notification beacon until a centralized control period end notification is transmitted. A wireless communication method comprising a communication control step of performing control of relaying the access point from the signal processing device and transmitting the relayed signal to the wireless terminal . The wireless communication method according to claim 4 , wherein, in the communication control step, a CFP (Contention Free Period) of a PCF (Point Coordination Function) is used as the priority transmission period, and the delivery confirmation is included in a polling packet. The wireless terminal uses the second transfer type identifier after transmitting the plurality of packets using the first transfer type identifier and before receiving the delivery confirmation regarding the first transfer type identifier. The wireless communication method according to claim 4 or 5 , wherein a plurality of other packets are transmitted.

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