JP2013026820A - Communication apparatus, communication method and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently transfer a received packet to an upper layer with a low delay.SOLUTION: A communication apparatus comprises a reception part that receives a packet, a response transmission part that, every time a packet group including two or more packets is received, transmits a response packet including information concerning a packet having an error occurring of the packet group, a packet transmission part that transmits a packet having no error occurring to an upper layer, and an error correction part that uses data of the packet having no error occurring to restore data of the packet having the error occurring. The response transmission part detects from the packet having no error occurring of the packet group a packet last received by the reception part, and transmits a response packet indicating that all the packets received prior to the detected packet have no error occurring.

Description

  The present technology relates to a communication device, a communication method, and a communication system.

  The IEEE 802.11 standard includes various technologies for speeding up wireless data transmission. One of them is a technique called packet aggregation. This technique is a technique for combining and transmitting a plurality of data packets. Further, as a technique used together with packet aggregation, there is a technique called block ACK. This technique is to return a block ACK composed of ACKs for each received data to the transmitting side at the timing when a plurality of data is received. When used with packet aggregation, a block ACK will be returned to the sender each time a combined data packet is received. The mechanism of packet aggregation and block ACK is also described in Patent Document 1 below, for example.

JP 2009-278542 A

  By using a mechanism of packet aggregation and block ACK, it is possible to reduce the occurrence frequency of waiting time such as IFS (Inter Frame Space) and time required for access control, and throughput is improved. However, because a block ACK is returned at the timing when a plurality of data packets are received, even if a missing data packet occurs in the middle, retransmission of the missing packet is not performed at the time when the missing packet occurs, and the receiving order of the data packets is It will be disturbed. Therefore, before the data packet is transferred to the upper layer, the data packet order control process (hereinafter, reorder process) is performed in the MAC layer.

  However, when the delay time allowed by the upper layer application is short, there is a concern that a data packet that is not allowed by the application is generated due to the delay caused by the reorder processing. In other words, the data packet may expire while the reorder process is being executed. Therefore, the present technology has been devised in view of the above circumstances, and can apply a mechanism equivalent to block ACK and efficiently transfer a data packet to an upper layer with low delay. It is intended to provide a new and improved communication device, communication method, and communication system.

  According to an aspect of the present technology, every time a packet group including two or more packets is received, a response packet including information on a packet in which an error has occurred in the packet group is received. A response transmission unit that transmits to the transmission side, a packet transfer unit that transfers a packet in which no error has occurred to an upper layer, and a packet in which an error has occurred using data of the packet in which the error has not occurred An error correction unit that restores data, and the response transmission unit detects and detects a packet received last by the reception unit among packets in which no error has occurred in the packet group. A communication device is provided that transmits a response packet indicating that no error has occurred for all packets received earlier than the packet.

  Further, according to another aspect of the present technology, a step of transferring a packet in which no error has occurred among received packets to an upper layer, and using data of the packet in which the error has not occurred A step of restoring data of a packet in which an error has occurred, and each time a packet group including two or more packets is received, a response packet including information on the packet in which an error has occurred in the packet group is sent to the transmission side. And transmitting, wherein the transmitting step detects a packet received last among packets in which no error has occurred in the packet group, and is received before the detected packet. A communication method is provided, which is a step of transmitting a response packet indicating that no error has occurred for all packets.

  According to another aspect of the present technology, a transmission unit that transmits a packet, a retransmission control unit that causes the transmission unit to retransmit a packet in which an error has occurred based on information included in a response packet received from a reception device, and Each time a packet group including two or more packets is received, a response packet including information regarding the packet in which an error has occurred in the packet group is transmitted. A response transmission unit that transmits the packet to the side, a packet transfer unit that transfers a packet in which no error has occurred to an upper layer, and data of a packet in which an error has occurred using the data of the packet in which no error has occurred An error correction unit that restores the packet, and the response transmission unit includes a packet that has no error in the packet group. And a communication system that detects a packet received last by the receiving unit and transmits a response packet indicating that no error has occurred for all packets received before the detected packet. .

  As described above, according to the present technology, a data packet can be efficiently transferred to an upper layer with low delay while applying a mechanism equivalent to block ACK.

It is explanatory drawing for demonstrating the system configuration example of a communication system. It is explanatory drawing for demonstrating speed-up technique. It is explanatory drawing for demonstrating speed-up technique. It is explanatory drawing for demonstrating speed-up technique. It is explanatory drawing for demonstrating speed-up technique. It is explanatory drawing for demonstrating speed-up technique. It is explanatory drawing for demonstrating speed-up technique. It is explanatory drawing for demonstrating speed-up technique. It is explanatory drawing for demonstrating an example of the retransmission control method used when applying a high-speed technique. It is explanatory drawing for demonstrating an example of the retransmission control method which can be utilized when applying a speed-up technique. It is explanatory drawing for demonstrating an example of the retransmission control method which can be utilized when applying a speed-up technique. It is explanatory drawing for demonstrating an example of the retransmission control method which can be utilized when applying a speed-up technique. It is explanatory drawing for demonstrating the structure of the transmitter which concerns on this embodiment. It is explanatory drawing for demonstrating the structure of the receiver which concerns on this embodiment. It is explanatory drawing for demonstrating the whole structure of the process sequence which the transmitter and receiver which concern on this embodiment perform. It is explanatory drawing for demonstrating the structure of the processing sequence which the transmitter and receiver which concern on this embodiment perform. It is explanatory drawing for demonstrating the structure of the processing sequence which the transmitter and receiver which concern on this embodiment perform. It is explanatory drawing for demonstrating the structure of the processing sequence which the transmitter and receiver which concern on this embodiment perform. It is explanatory drawing for demonstrating the structure of the processing sequence which the transmitter and receiver which concern on this embodiment perform. It is explanatory drawing for demonstrating the structure of the processing sequence which the transmitter and receiver which concern on this embodiment perform. It is explanatory drawing for demonstrating the structure of the processing sequence which the transmitter and receiver which concern on this embodiment perform. It is explanatory drawing for demonstrating the structure of the processing sequence which the transmitter and receiver which concern on this embodiment perform. It is explanatory drawing for demonstrating the restoration method of the missing data by erasure | elimination correction. It is explanatory drawing which showed an example of the user interface which a user utilizes when requesting low-delay processing. It is explanatory drawing which showed the structural example of the 802.11 Management Action frame which can be utilized when a low-delay process is requested | required from the transmission side. It is explanatory drawing which showed the structural example of the 802.11 Data frame which can be utilized when a low-delay process is requested | required from the transmission side. It is explanatory drawing which showed the structural example of the 802.11 Data frame which can be utilized when a low-delay process is requested | required from the transmission side. It is explanatory drawing which showed the structural example of the 802.11 Data frame which can be utilized when a low-delay process is requested | required from the transmission side.

  Hereinafter, preferred embodiments according to the present technology will be described in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

[About the flow of explanation]
Here, the flow of explanation described below will be briefly described.

  First, a configuration example of the communication system 10 will be described with reference to FIG. Next, a speed-up technique applicable to the communication system 10 will be described with reference to FIGS. Of these, the outline of the present embodiment will also be briefly described. Next, configuration examples of the transmission device 11 and the reception device 12 included in the communication system 10 according to the present embodiment will be described with reference to FIGS. 12 and 13. Next, a communication method and a communication control method according to the present embodiment will be described with reference to FIGS. Finally, the technical idea of the present embodiment will be summarized and the effects obtained from the technical idea will be briefly described.

(Description item)
1: Introduction 1-1: High-speed technology using packet aggregation
1-1-1: Configuration of the communication system 10
1-1-2: Overview of packet aggregation
1-1-3: Data processing in the MAC layer on the transmission side
1-1-4: Mechanism of block ACK 1-2: Retransmission control when high speed technology is applied
1-2-1: Cases where allowable delay time is long
1-2-2: Case where allowable delay time is short
1-2-3: Invalidation of reorder processing
1-2-4: Outline of the present embodiment 2: Embodiment 2-1: Device configuration
2-1-1: Configuration of transmitting apparatus 11 (AP)
2-1-2: Configuration of receiving apparatus 12 (STA) 2-2: Sequence
2-2-1: Overall processing flow
2-2-2: Processing flow when there is a low-latency request
2-2-3: (Appendix) Missing data recovery method 2-3: Low delay request notification method
2-3-1: Notification of low-latency request by user operation
2-3-2: Notification of low-latency requests using messaging
2-3-3: Notification of low-latency request using header information 3: Summary

<1: Introduction>
Prior to describing the technology according to the present embodiment in detail, a data transmission method related to the technology will be briefly introduced. Specifically, a data transmission speedup technique using packet aggregation and a retransmission control technique that can be used when the speedup technique is applied will be introduced. An outline of the technology according to the present embodiment will also be described.

[1-1: High-speed technology using packet aggregation]
First, a technique for speeding up data transmission using packet aggregation will be described. Here, the mechanism of packet aggregation and block ACK defined in the IEEE 802.11n standard will be described. It should be noted that the scope of application of the technology according to the present embodiment is not limited to these technologies.

(1-1-1: Configuration of Communication System 10)
First, a system configuration example (communication system 10) assumed in the following description will be described with reference to FIG. FIG. 1 is an explanatory diagram showing the configuration of the communication system 10.

  As illustrated in FIG. 1, the communication system 10 mainly includes a transmission device 11 and a reception device 12. For example, the transmission device 11 functions as an access point (AP). The receiving device 12 functions as a station (STA). In this example, the transmission device 11 is connected to the communication network 5. Therefore, the transmission device 11 can communicate with a communication device existing outside the communication system 10 via the communication network 5. For example, the transmission device 11 receives data to be transmitted to the reception device 12 via the communication network 5. The transmission device 11 transmits data received from the reception device 12 to an external communication device via the communication network 5.

  Further, the transmission device 11 can wirelessly transmit data to the reception device 12. For example, the transmission device 11 wirelessly transmits data received via the communication network 5 to the reception device 12. Conversely, the receiving device 12 can wirelessly transmit data such as ACK to the transmitting device 11. In the following, for convenience of explanation, downlink wireless transmission in which data is wirelessly transmitted from the transmission device 11 to the reception device 12 is considered. However, techniques for wireless transmission such as uplink, direct link, and ad hoc network will be described later. Is applicable as well.

  Moreover, although the wireless transmission between AP and STA is given as an example, the transmission device 11 and the reception device 12 may have any device form. Applicable device forms include, for example, a mobile phone, an information terminal, a game machine, a television receiver, a recording / playback device, a video device, an imaging device, a car navigation system, and an information home appliance. In the following, the description will be made in consideration of wireless transmission, but the technique described later can be similarly applied to wired data transmission. Thus, the system configuration of the communication system 10 can be modified as appropriate according to the embodiment. However, in the following description, the description will proceed with the wireless transmission between the AP and the STA in mind in order to make the technical contents easier to understand.

  The system configuration example of the communication system 10 has been described above.

(1-1-2: Overview of packet aggregation)
Next, an overview of packet aggregation will be described with reference to FIG. FIG. 2 is an explanatory diagram for explaining an outline of packet aggregation. The diagram of the transmission method A shown in FIG. 2 shows a mechanism of a general data transmission method that does not perform packet aggregation. On the other hand, the diagram of the transmission method B shown in FIG. 2 shows the mechanism of the data transmission method for performing packet aggregation.

  For example, consider a case where data # 1 to # 3 are transmitted. In the case of transmission method A, data # 1 to # 3 are transmitted individually one by one. Therefore, an access control signal reception period, SIFS (Short Inter Frame Space), and a response signal reception period are required before and after transmission of each data. That is, when data # 1 to # 3 are transmitted, the access control signal reception period, SIFS, and response signal reception period occur three times. On the other hand, in the case of transmission method B, data # 1 to # 3 are transmitted together. Therefore, the access control signal reception period, SIFS, and response signal reception period occur only once. As a result, as shown in FIG. 2, overhead is reduced and transmission efficiency is improved.

  The outline of packet aggregation has been described above. As described above, when packet aggregation is applied, the time required for access control, response signal reception, and the like is shortened, and the data transmission efficiency can be improved.

(1-1-3: Data processing in transmission side MAC layer)
Next, data processing in the MAC layer on the transmission side when applying packet aggregation will be described with reference to FIGS. 3-5 is explanatory drawing for demonstrating the data processing in the transmission side MAC layer in the case of applying a packet aggregation. The transmission-side MAC layer refers to the function of the MAC layer that the transmission apparatus 11 has.

  As shown in FIG. 3, when data is transferred from the upper layer to the MAC layer, the transmitting-side MAC layer executes MSDU aggregation (S11). However, MSDU is an abbreviation for MAC Service Data Unit. At this time, as shown in FIG. 4, the transmitting-side MAC layer generates a A-MSDU by combining a plurality of A-MSDU subframes including a subframe header, MSDU, and padding. This A-MSDU is stored in the frame body field of the MPDU. However, A-MSDU is an abbreviation for Aggregation MSDU. MPDU is an abbreviation for MAC Protocol Data Unit.

  Refer to FIG. 3 again. After executing the MSDU aggregation, the transmission-side MAC layer assigns a sequence number to the generated A-MSDU and generates an MPDU (S12). Next, the transmission side MAC layer encrypts the MSDU (S13). Next, the transmission side MAC layer executes fragmentation (S14). Fragmentation is a process for dividing a frame and reducing the transmission unit when the size of the frame to be transmitted is large. After executing the fragmentation, the transmission side MAC layer encrypts the MPDU (S15). Next, the transmitting side MAC layer adds a header and FCS (S16). However, FCS is an abbreviation for Frame Check Sequence.

  After adding the header and FCS, the transmitting-side MAC layer executes MPDU aggregation to generate A-MPDU (S17). At this time, as shown in FIG. 5, the transmitting-side MAC layer generates a A-MPDU by combining a plurality of A-MPDU subframes including MPDU delimiters, MPDUs, and padding. However, this A-MPDU is an abbreviation for Aggregation MAC Protocol Data Unit. The MPDU delimiter is a field indicating the boundary of the A-MPDU subframe. As described above, the A-MPDU generated in the transmission-side MAC layer is transferred to the physical layer.

  The data processing in the transmission side MAC layer when applying packet aggregation has been described above. In the receiving MAC layer, the above reverse processing is executed, and each MSDU is taken out. Note that the processing in steps S11 to S15 may be omitted.

(1-1-4: Mechanism of block ACK)
Next, the mechanism of block ACK will be described with reference to FIGS. 6 and 7 are explanatory diagrams for explaining the mechanism of the block ACK. In the case of a general transmission method, a response to one data is performed using one ACK. However, as described with reference to FIG. 2, if a response is returned for each piece of data, overhead increases and it is difficult to achieve high transmission efficiency. Under such circumstances, as shown in FIG. 6, a mechanism has been devised to return a block ACK in which responses to a plurality of data are collected at the timing of receiving a plurality of data.

  FIG. 6 schematically shows a block ACK mechanism (hereinafter referred to as 802.11e type) adopted in the IEEE 802.11e standard. Since the IEEE 802.11e standard does not introduce a mechanism for packet aggregation, a plurality of data are sequentially transmitted without being combined. However, the response to the plurality of data is performed using one block ACK. In the example of FIG. 6, a block ACK request is transmitted from the transmission side at a timing when N pieces of data are transmitted from the transmission side to the reception side. In response to this block ACK request, a block ACK is returned from the receiving side to the transmitting side. When such a mechanism is applied, transmission efficiency is improved by the amount of time required for response.

  On the other hand, FIGS. 7A and 7B schematically show a block ACK mechanism (hereinafter referred to as 802.11n type) adopted in the IEEE 802.11n standard. In the IEEE802.11n standard, a mechanism for packet aggregation is introduced, so that a plurality of data are combined and transmitted. And the response with respect to A-MPDU which combined several data is performed using one block ACK. As shown in FIG. 7A, a block ACK request is transmitted from the transmission side at the timing when the A-MPDU is transmitted from the transmission side to the reception side, and a block ACK is transmitted from the reception side to the transmission side in response to this block ACK request. returned. Alternatively, as shown in FIG. 7B, the A-MPDU is transmitted from the transmission side to the reception side, and a block ACK is returned from the reception side to the transmission side according to the A-MPDU. When such a mechanism is applied, transmission efficiency is improved by the amount of time required for response.

  The mechanism of block ACK has been described above.

[1-2: Retransmission control when applying high-speed technology]
When the above speed-up technology is applied, transmission efficiency can be increased. However, when the block ACK mechanism is applied, there is a possibility that the missing data may not be retransmitted at the timing when the data loss occurs, and there is a concern that the reception order may be disturbed. Therefore, in the receiving-side MAC layer, when performing retransmission control of missing data, order control of data transferred to an upper layer is performed. Such processing relating to retransmission control of missing data and data order control is called reorder processing. Hereinafter, this reorder processing will be considered.

(1-2-1: Case where allowable delay time is long)
First, with reference to FIG. 8, a description will be given of missing data retransmission control and data order control executed in a system configuration using a block ACK mechanism. FIG. 8 is an explanatory diagram for explaining the flow of processing related to retransmission control of missing data and data order control. In FIG. 8, in order to facilitate understanding of the flow of processing, main processes related to retransmission control and order control among the processes executed in the transmission side MAC layer, the reception side MAC layer, and the reception side upper layer are shown. Only is shown schematically.

  Assume that data # 1 to # 4 are transmitted from the transmission side MAC layer to the reception side MAC layer as shown in FIG. Also assume that an error occurs in data # 2 in the transmission path and data # 2 is lost. In this case, only the data # 1, # 3, and # 4 reach the receiving side MAC layer. At this time, data loss detection is performed in the receiving-side MAC layer, and data # 2 loss is detected. Therefore, the receiving-side MAC layer transfers data # 1 having a sequence number before the missing data # 2 to the receiving-side higher layer, and accumulates data # 3 and # 4. Furthermore, the receiving side MAC layer returns a block ACK to the transmitting side MAC layer. This block ACK includes information indicating that reception of data # 2 has failed.

  The transmission side MAC layer that has received the block ACK retransmits data # 2 in which a loss is detected in the reception side MAC layer at the previous data transmission, together with data # 5 to # 8 to be transmitted next. That is, data # 5 to # 8 and # 2 are transmitted from the transmission side MAC layer to the reception side MAC layer. The receiving side MAC layer receiving these data # 5 to # 8 and # 2 accumulates data # 5 to # 8, and transfers data # 2 having a smaller sequence number to the receiving side upper layer first. When the data # 2 is transferred, the receiving side MAC layer transfers the stored data # 3 to # 8 to the receiving side upper layer. Then, the reception side MAC layer returns a block ACK to the transmission side MAC layer. This block ACK includes information indicating that all data up to data # 8 has been normally received.

  As described above, the receiving-side MAC layer transfers data having a sequence number smaller than the missing data to the receiving-side higher layer, and stores the data having the larger sequence number than the missing data. Controls the order of data transferred to the upper layer. The receiving MAC layer transfers the retransmitted data to the receiving upper layer, and then transfers the stored data to the receiving upper layer. Certainly, by executing such processing, even if data loss occurs, it is possible to correctly maintain the order of data transferred to the upper layer on the receiving side. However, since the block ACK mechanism is applied, it takes a long time for the missing data to be retransmitted, and the missing data and the data accumulated in the receiving MAC layer are transferred to the receiving upper layer. A large delay will occur.

  In a case as shown in FIG. 8 where the upper-layer application on the receiving side allows a sufficiently large delay (case where the packet expiration date is long), even if a large delay occurs due to the reorder processing as described above. Data is received normally. For example, in the example of FIG. 8, since the data # 2 is transferred to the receiving upper layer within the expiration date of the data # 2, the data # 2 is normally received by the receiving upper layer application. Further, since the data # 3 to # 8 stored in the receiving MAC layer are also transferred to the receiving upper layer within the expiration date, the data # 3 to # 8 are received by the receiving upper layer application. Is received normally.

(1-2-2: Case where allowable delay time is short)
However, as shown in FIG. 9, in the case where the application on the upper layer on the receiving side does not allow a sufficiently large delay, if a large delay occurs due to the reorder processing as described above, it becomes a target of the reorder processing. Data will not be received normally. In the example of FIG. 9, the data # 2 retransmitted from the transmission side MAC layer and the data # 3 to # 8 accumulated in the reception side MAC layer waiting for retransmission of the data # 2 are all expired. Yes.

  The above-described packet aggregation mechanism has a characteristic that as the number of packets to be combined increases, overhead is reduced and transmission efficiency is improved. Similarly, the transmission efficiency improves as the frequency of block ACK is reduced. However, as can be easily inferred from the reorder processing mechanism shown in FIGS. 8 and 9, when the frequency of block ACK decreases, retransmission of missing data is delayed. In addition, the waiting time until the data stored in the MAC layer on the receiving side is transferred to the upper layer on the receiving side becomes longer. Therefore, when using an application with a short allowable delay time (hereinafter referred to as a low-delay application), considering the delay due to the reorder processing, the effect of improving the transmission efficiency obtained by the above-described speed-up technique is limited. End up.

(1-2-3: Invalidation of reorder processing)
Therefore, as shown in FIG. 10, when using a low-latency application, a mechanism has been devised that invalidates the reorder processing. However, if the reorder process is invalidated, the order of data transferred to the upper layer on the receiving side is disturbed when data loss occurs. Therefore, in the example of FIG. 10, a mechanism for performing erasure correction for restoring missing data is provided in the upper layer on the receiving side. The erasure correction is a process of restoring missing data using normally received data. The erasure correction mechanism will be described in detail later.

  Thus, by invalidating the reorder processing and combining the mechanism of erasure correction, the low-delay application can correctly receive data while maintaining the data order in the upper layer on the receiving side correctly. However, as shown in FIG. 10, since retransmission control of missing data is performed regardless of whether or not reorder processing is performed, it is necessary to perform data duplication detection and duplication data discarding in the upper layer on the receiving side.

  In the example of FIG. 10, an error has occurred in data # 2, but the receiving-side MAC layer immediately transfers data # 1, # 3, and # 4 to the receiving-side higher layer, indicating an error in data # 2. A block ACK is transmitted to the transmitting MAC layer. Therefore, the transmission side MAC layer transmits data # 2 to the reception side MAC layer together with data # 5 to # 8. However, the upper layer on the receiving side restores data # 2 using data # 1, # 3, and # 4 transferred from the receiving side MAC layer. Therefore, the data # 2 transferred from the receiving side MAC layer to the receiving side upper layer is regarded as duplicate data in the receiving side upper layer and discarded.

  As described above, when a low-latency application is used, data can be transferred to the upper layer on the receiving side within the expiration date by invalidating the reorder process. Therefore, even when the number of data to be combined by packet aggregation is increased or the frequency of block ACK is reduced, data can be received correctly in a low-delay application. As a result, even when a low-delay application is used, it is possible to enjoy the high transmission efficiency improvement effect obtained by the above-described speed-up technology.

(1-2-4: Overview of the present embodiment)
However, as can be inferred from the example of FIG. 10, it is redundant to deliberately retransmit the data to be restored in the upper layer on the receiving side, or to detect and discard the duplicated data. Absent. Therefore, the present inventors have devised a mechanism (technique according to the present embodiment) for omitting such redundant processing. This mechanism contributes to load reduction and throughput improvement. Hereinafter, the outline of the technique according to the present embodiment will be described with reference to FIG. FIG. 11 is an explanatory diagram showing an outline of the technology according to the present embodiment.

  Assume that data # 1 to # 4 are transmitted from the transmission side MAC layer to the reception side MAC layer as shown in FIG. Also assume that an error occurs in data # 2 in the transmission path and data # 2 is lost. In this case, only the data # 1, # 3, and # 4 reach the receiving side MAC layer. At this time, the receiving-side MAC layer performs data loss detection to detect data # 2 loss, but immediately transfers data # 1, # 3, and # 4 to the receiving-side higher layer. The upper layer on the receiving side performs erasure correction using data # 1, # 3, and # 4 transferred from the MAC layer on the receiving side, and restores data # 2.

  After transferring the data # 1, # 3, and # 4 to the upper layer on the receiving side, the receiving side MAC layer returns a block ACK to the transmitting side MAC layer. However, this block ACK indicates that data up to data # 4 has been correctly received. Therefore, the transmitting-side MAC layer that has received this block ACK recognizes that the data # 1 to # 4 have been correctly received, and does not retransmit the missing data # 2, but the data # 5 to be transmitted next. ~ # 8 is transmitted to the MAC layer on the receiving side. The receiving-side MAC layer that has received data # 5 to # 8 immediately transfers the received data # 5 to # 8 to the upper layer on the receiving side and confirms that all the data up to data # 8 has been received correctly. The indicated block ACK is transmitted to the transmitting side MAC layer.

  In the case of the mechanism shown in FIG. 11, since the reorder process is not performed, data can be transferred to the upper layer on the receiving side within the expiration date requested by the low-delay application. In addition, since the missing data # 2 is restored by erasure correction in the upper layer on the receiving side, the data order is correctly maintained in the upper layer on the receiving side. Further, since the data # 2 lost in the transmission path is not retransmitted, redundant processing such as duplication detection and duplication data discarding performed in the mechanism illustrated in FIG. 10 is not performed in the upper layer on the receiving side. Will come to an end. As a result, transmission efficiency can be further improved.

  Heretofore, various mechanisms relating to retransmission control, order control, and the like, and an overview of the technology according to the present embodiment have been described. Hereinafter, details of the technology according to the present embodiment will be described.

<2: Embodiment>
An embodiment of the present technology will be described.

[2-1: Device configuration]
First, configurations of the transmission device 11 and the reception device 12 that can realize the technology according to the present embodiment will be described. Note that, as already described, for the sake of explanation, the description proceeds with the system configuration illustrated in FIG. 1 in mind, but the scope of application of the technology according to the present embodiment is not limited to this. Further, the technology according to the present embodiment can be applied not only to a wireless data transmission method but also to a wired data transmission method.

(2-1-1: Configuration of Transmitting Device 11 (AP))
The configuration of the transmission device 11 according to the present embodiment will be described with reference to FIG. FIG. 12 is an explanatory diagram for describing a configuration of the transmission device 11 according to the present embodiment. As illustrated in FIG. 12, the transmission device 11 includes, for example, a wired interface 111, a data processing unit 112, a transmission processing unit 113, and a wireless interface 114.

  When data to be transmitted to the receiving device 12 is input via the communication network 5, this data is input to the data processing unit 112 via the wired interface 111. When data is input, the data processing unit 112 generates a packet using the input data. The packet generated by the data processing unit 112 is input to the transmission processing unit 113. When a packet is input, the transmission processing unit 113 adds information such as a header and an error correction code to the input packet and inputs the packet to the wireless interface 114. In addition, when applying the mechanism of packet aggregation, the transmission process part 113 performs the process which concerns on the production | generation of A-MPDU as shown in FIG. The wireless interface 114 modulates the input packet to generate a modulated signal, and transmits the modulated signal to the receiving device 12 via the antenna.

(2-1-2: Configuration of Receiving Device 12 (STA))
Next, the configuration of the receiving device 12 according to the present embodiment will be described with reference to FIG. FIG. 13 is an explanatory diagram for describing a configuration of the receiving device 12 according to the present embodiment. As illustrated in FIG. 13, the reception device 12 includes, for example, a wireless interface 121, a transmission processing unit 122, a storage unit 123, and a data processing unit 124.

  The modulated signal transmitted by the transmission device 11 as described above is received by the wireless interface 121 via the antenna. When receiving the modulated signal, the wireless interface 121 restores the packet by performing demodulation processing on the received modulated signal. The restored packet is input to the transmission processing unit 122. When a packet is input, the transmission processing unit 122 analyzes the header of the input packet. Further, the transmission processing unit 122 accumulates packets using the storage unit 123 or transmits a block ACK to the transmission device 11 via the wireless interface 121.

  Further, when applying the packet aggregation mechanism, the transmission processing unit 122 performs reverse processing of the processing illustrated in FIG. 3 to perform A-MPDU decomposition. When the header analysis and the A-MPDU decomposition are completed, the packet is transferred from the transmission processing unit 122 to the data processing unit 124. The data processing unit 124 extracts data from the transferred packet. In addition, the data processing unit 124 performs data loss correction as necessary, and performs restoration processing of missing data. Then, the data processing unit 124 executes the application using the finally obtained data.

  The configuration examples of the transmission device 11 and the reception device 12 have been described above. Note that the configuration illustrated here is merely an example and can be modified as appropriate.

[2-2: Sequence]
Next, operations of the transmission device 11 and the reception device 12 according to the present embodiment will be described.

(2-2-1: Overall processing flow)
First, an overall flow of processing executed by the transmission device 11 and the reception device 12 will be described with reference to the sequence diagram of FIG. FIG. 14 is a sequence diagram illustrating an overall flow of processing executed by the transmission device 11 and the reception device 12.

  As shown in FIG. 14, first, the transmission device 11 and the reception device 12 establish a data link (S101). When the data link is established, the receiving device 12 detects a request for low delay processing (hereinafter referred to as a low delay request) issued by an upper layer application (S102), and switches the processing according to the detection result (S103). . If there is a low delay request, the receiving apparatus 12 proceeds with the process to step S104. On the other hand, when there is no low delay request, the receiving apparatus 12 proceeds with the process to step S105.

  When the process has proceeded to step S104, the receiving device 12 invalidates the reorder process (S104), and the process proceeds to step S105. When the receiving apparatus 12 advances the process to step S105, packet transmission / reception is performed between the transmitting apparatus 11 and the receiving apparatus 12 (S105). If there is no low delay request, a normal reception process as illustrated in FIG. 8 is executed in step S105. On the other hand, if there is a low delay request, a characteristic reception process as illustrated in FIG. 11 is executed in step S105.

  The overall flow of processing executed by the transmission device 11 and the reception device 12 has been described above.

(2-2-2: Processing flow when there is a low delay request)
Next, the flow of processing executed in step S105 when there is a low delay request will be described in more detail.

(Case 1: See FIG. 11)
First, consider the case illustrated in FIG. 11 (hereinafter, Case 1). Case 1 shows a situation in which when a predetermined number of data (four in the example of FIG. 11) corresponding to one block ACK is transmitted, data whose order is not the end is lost. In the example of FIG. 11, the data # 2 is missing, but the case where the data # 1 and the data # 3 are missing also falls under Case 1. In case 1, it is possible to restore missing data by erasure correction using normally received data. Therefore, even if missing data exists, all data can be obtained in the correct order in the upper layer on the receiving side. Therefore, in case 1, it is not necessary to retransmit missing data.

  Therefore, in the case of Case 1, the receiving apparatus 12 according to the present embodiment transmits a block ACK indicating that the data up to the end has been normally received to the transmitting apparatus 11. A more detailed processing flow is as shown in FIG. As illustrated in FIG. 15, first, the transmission device 11 transmits data # 1 to # 4 (S131). Next, the receiving device 12 performs loss detection by the function of the MAC layer, and detects a loss of data # 2 (S132). Next, the receiving device 12 transfers the normally received data # 1, # 3, and # 4 from the MAC layer to the upper layer (S133). Next, the receiving device 12 transmits a block ACK to the transmitting device 11 by the function of the MAC layer (S134). This block ACK indicates that all data up to data # 4 has been normally received.

  In addition, the receiving device 12 performs erasure correction on the missing data # 2 by the upper layer function, and restores the data # 2 (S135). On the other hand, the transmission device 11 that has received the block ACK transmits data # 5 to # 8 to the reception device 12 by the function of the MAC layer (S136). Next, the receiving device 12 performs defect detection by the function of the MAC layer, and detects that there is no defect in the data # 5 to # 8 (S137). Then, the receiving device 12 transfers the data # 5 to # 8 from the MAC layer to the upper layer (S138). Thereafter, processing such as block ACK transmission, data transmission, loss detection, data correction, and erasure correction is performed.

  As described above, when a loss occurs in the data whose order is not the end of the predetermined number of data corresponding to one block ACK, it is possible to use erasure correction without retransmitting the missing data. All data can be received correctly. Therefore, by adopting the block ACK configuration as described above, it is possible to avoid redundant processing and achieve reduction of load and improvement of transmission efficiency.

(Case 2: See FIGS. 16 and 17)
However, as shown in FIG. 16, in the case where a defect occurs in the data in the end of the predetermined number of data corresponding to one block ACK, the erasure correction based on the data normally received in the past is performed. In some cases, missing data cannot be recovered. In such a case, as shown in FIG. 16, the upper layer on the receiving side waits for the next data to be transmitted and performs erasure correction of the missing data. The upper layer on the receiving side adjusts the order of data when passing the data to the low-latency application. In the example of FIG. 16, after the receiving upper layer receives data # 5, erasure correction of the missing data # 4 is performed. For this reason, the upper layer on the receiving side adjusts the order of data # 4 and data # 5 and then passes the data to the application.

  The block ACK returned from the receiving MAC layer to the transmitting MAC layer indicates that all data up to the last received data # 3 has been successfully received. Data # 4 is retransmitted. Therefore, the upper layer on the receiving side performs data duplication detection and discarding of duplicate data. Note that, as shown in FIG. 17, the same processing is performed when data having the last data in the order and data having a sequence number following that data are missing from a predetermined number of data corresponding to one block ACK. . In the example of FIG. 17, since data # 3 and # 4 are missing, erasure correction, retransmission control, duplication detection, and discarding of duplication data for data # 3 and # 4 are performed.

  In the case shown in FIGS. 16 and 17 (hereinafter, Case 2), the flow of processing by the transmission device 11 and the reception device 12 is as shown in FIG. As shown in FIG. 18, first, the transmission device 11 transmits data # 1 to # 4 (S141). Next, the receiving device 12 performs loss detection by the function of the MAC layer (S142). By this loss detection, the receiving device 12 can detect that the last data (for example, the last A-MDPU data) is missing. In this example, since the data # 4 is missing, the receiving device 12 detects that the last data is missing. Further, the receiving device 12 can infer the loss of data # 4 from the detection result.

  Next, the receiving device 12 transfers the normally received data # 1 to # 3 from the MAC layer to the upper layer (S143). Next, the receiving device 12 transmits a block ACK to the transmitting device 11 by the function of the MAC layer (S144). This block ACK indicates that all data up to data # 3 that has been normally received successfully has been normally received.

  In addition, the receiving device 12 tries to perform erasure correction on the missing data # 4 by using the upper layer function (S145). However, in this case, restoration of data # 4 fails. On the other hand, the transmission device 11 that has received the block ACK transmits the data # 5 to # 8 and # 4 to the reception device 12 by the function of the MAC layer (S146). Next, the receiving device 12 performs loss detection by the function of the MAC layer, and detects that there is no loss in the data # 5 to # 8 and # 4 (S147). Then, the receiving device 12 sequentially transfers the data # 5 to # 8 and # 4 from the MAC layer to the upper layer (S148).

  In addition, the receiving device 12 performs erasure correction on the missing data # 4 by the upper layer function, and restores the data # 4 (S149). At this time, the receiving apparatus 12 performs erasure correction without waiting for the transfer of the data # 5 to # 8 and # 4 to be completed. For example, when the transfer of the data # 5 is completed, the receiving device 12 performs erasure correction using the data # 5. When the data # 4 is restored, the receiving device 12 detects the duplication of the data # 4 by the upper layer function, detects the duplication of the data # 4, and discards the data # 4 (S150). Thereafter, processing such as block ACK transmission, data transmission, loss detection, data correction, and erasure correction is performed.

  As described above, out of the predetermined number of data corresponding to one block ACK, when a loss occurs in the data at the end of the order, by performing erasure correction using the data transmitted next, Missing data can be restored. However, when the block ACK is configured as described above, processing such as data duplication detection and duplication data discarding is added.

(Modification 1: Configuration that does not request retransmission even if the end packet is missing)
Accordingly, in order to prevent processing such as data duplication detection and duplication data discarding from occurring even when data in the last order among the predetermined number of data corresponding to one block ACK has occurred, FIG. Devised a mechanism as shown below (hereinafter, modified example 1). In the case of the first modification, the reception-side MAC layer returns a block ACK indicating that all the predetermined number of data corresponding to one block ACK has been normally received to the transmission-side MAC layer. For this reason, even when data with the end in the order is lost, redundant processing such as detection of data duplication and discarding of duplicate data does not occur.

  In the case of the modification 1, the flow of processing by the transmission device 11 and the reception device 12 is as shown in FIG. As shown in FIG. 20, first, the transmission device 11 transmits data # 1 to # 4 (S151). Next, the receiving device 12 performs loss detection by the function of the MAC layer (S152). By this loss detection, the receiving device 12 can detect that the last data (for example, the last A-MDPU data) is missing. In this example, since the data # 4 is missing, the receiving device 12 detects that the last data is missing. Further, the receiving device 12 can infer the loss of data # 4 from the detection result.

  Next, the receiving device 12 transfers the normally received data # 1 to # 3 from the MAC layer to the upper layer (S153). Next, the receiving device 12 transmits a block ACK to the transmitting device 11 by the function of the MAC layer (S154). This block ACK indicates that all data up to data # 4 has been normally received.

  In addition, the receiving device 12 attempts to perform erasure correction on the missing data # 4 by using the upper layer function (S155). However, in this case, restoration of data # 4 fails. On the other hand, the transmission device 11 that has received the block ACK transmits data # 5 to # 8 to the reception device 12 by the function of the MAC layer (S156). Next, the receiving device 12 performs loss detection by the function of the MAC layer, and detects that there is no loss in the data # 5 to # 8 (S157). Then, the receiving device 12 sequentially transfers the data # 5 to # 8 from the MAC layer to the upper layer (S158).

  In addition, the receiving device 12 performs erasure correction on the missing data # 4 by the upper layer function, and restores the data # 4 (S159). At this time, the receiving apparatus 12 performs erasure correction without waiting for the transfer of the data # 5 to # 8 to be completed. For example, when the transfer of the data # 5 is completed, the receiving device 12 performs erasure correction using the data # 5. Thereafter, processing such as block ACK transmission, data transmission, loss detection, data correction, and erasure correction is performed.

  As described above, even when a missing data occurs in the data in the order among the predetermined number of data corresponding to one block ACK, the lost data is not retransmitted and erasure correction is used. All data can be received correctly. Therefore, by adopting the block ACK configuration as described above, it is possible to avoid redundant processing and achieve reduction of load and improvement of transmission efficiency.

(Modification 2: Waiting for erasure correction result and returning BlockACK)
However, the mechanism of the modification 1 is configured assuming that missing data can be restored by erasure correction at a high rate. Therefore, if data loss frequently occurs and it becomes difficult to restore lost data by erasure correction, it may be difficult to maintain the transmission quality required by the application. In particular, when using an application that requires high transmission quality, it is desirable to have a mechanism that requests retransmission of data as necessary. For example, it is conceivable to modify the mechanism as shown in FIG. 21 (hereinafter, modified example 2).

  As shown in FIG. 21, first, the transmission device 11 transmits data # 1 to # 4 (S161). Next, the receiving device 12 performs defect detection by the function of the MAC layer (S162). By this loss detection, the receiving device 12 can detect that the last data (for example, the last A-MDPU data) is missing. In this example, since the data # 4 is missing, the receiving device 12 detects that the last data is missing. Further, the receiving device 12 can infer the loss of data # 4 from the detection result.

  Next, the receiving device 12 transfers the normally received data # 1 to # 3 from the MAC layer to the upper layer (S163). Next, the receiving device 12 performs erasure correction of the data # 4 by the upper layer function (S164). Next, the receiving apparatus 12 notifies the erasure correction result (hereinafter, correction result R) from the upper layer to the MAC layer (S165). Next, the receiving device 12 transmits a block ACK to the transmitting device 11 by the function of the MAC layer (S166).

  At this time, the receiving device 12 switches the configuration of the block ACK according to the content of the correction result R. For example, when the data # 4 can be restored, the block ACK indicates that all data up to the data # 4 has been normally received. On the other hand, if the data # 4 cannot be restored, the block ACK indicates that all data up to the data # 3 has been normally received. The transmission apparatus 11 that has received this block ACK transmits data # 5 to # 8 or data # 5 to # 8 and # 4 to the reception apparatus 12 by the function of the MAC layer according to the contents of the block ACK. (S167). Thereafter, processing such as block ACK transmission, data transmission, loss detection, data correction, and erasure correction is performed.

  In the case of the first modification, since the missing data is retransmitted when the erasure correction fails, the transmission quality is maintained. Further, since the lost data is not retransmitted when the erasure correction is successful, it is possible to reduce the load and improve the transmission efficiency.

  The operations of the transmission device 11 and the reception device 12 according to the present embodiment have been described above.

(2-2-3: (Appendix) How to restore missing data)
Here, with reference to FIG. 22, a supplementary description will be given of a method for restoring missing data by erasure correction. FIG. 22 is an explanatory diagram schematically showing a method for restoring missing data by erasure correction. The missing data restoration method described here is an example, and the available missing data restoration method is not limited to this.

  For example, consider a case where data # 1 to # 4 are transmitted and data # 2 is lost in the transmission path. In this case, using the calculation result (Result) obtained by calculating exclusive OR for each bit of data # 1 to # 4, data # 2 can be restored from data # 1, # 3, and # 4. It becomes possible. Specifically, as shown in FIG. 22, data # 2 is obtained by calculating an exclusive OR for each bit of data # 1, # 3, # 4 and operation result Result. The calculation result Result is calculated by the upper layer on the transmission side and provided to the upper layer on the reception side. Although the calculation contents for restoring data # 2 have been described here, the same applies to other data.

  In the above, a brief description of the method for restoring missing data by erasure correction was added.

[2-3: Low delay request notification method]
Here, a method for notifying a low delay request will be described.

(2-3-1: Notification of low delay request by user operation)
First, a method for notifying a low delay request by a user operation will be described with reference to FIG. FIG. 23 is an explanatory diagram showing an example of a user interface used for a user operation when notifying a low delay request.

  Note that processing such as display of the user interface and detection of a user operation on the user interface is executed by an input / output unit (not shown) mounted on the receiving device 12. For example, the user interface display can be realized using a display device such as a CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display), or an ELD (ElectroLuminous Display). Moreover, detection of user operation is realizable using input devices, such as a touch sensor, a keyboard, a mouse | mouth, a remote controller, and a button.

  The input / output unit as described above displays a selection screen as shown in FIG. On this selection screen, for example, a MAC address for selecting a transmission source of a packet for which reorder processing is to be invalidated is displayed. Therefore, the user who wants to select the MAC address “AA-AA-AA-AA-AA-AA” may check the check column displayed on the left side of the MAC address.

  Further, on this selection screen, a traffic ID (hereinafter referred to as TID) of a packet for which reorder processing is to be invalidated is displayed. Therefore, a user who wants to select a TID included in a packet whose reorder processing is to be invalidated may check the check column displayed on the left side of the TID. The TID is identification information used for identifying a queue in which a packet is stored.

  By checking the check box as described above and then pressing the OK button, the reorder processing invalidation for the target packet becomes valid. Note that other information may be used instead of the MAC address. For example, a method of using the machine name or IP address of the transmission device 11 instead of the MAC address is conceivable. Also, other information can be used instead of TID. For example, a method of using a port number or the like instead of TID can be considered.

(2-3-2: Notification of low-latency request using messaging)
Next, a low delay request notification method using messaging from the transmission device 11 to the reception device 12 will be described with reference to FIG. FIG. 24 is an explanatory diagram showing the configuration of a management action frame defined in the IEEE 802.11 standard.

  When using messaging, the transmission device 11 transmits a low-delay request for requesting invalidation of the reordering process to the reception device 12 prior to transmission of traffic. At this time, the transmission device 11 stores (so-called encapsulate) a low delay request in a data packet that is not read by the reception-side MAC layer but is read by the reception-side upper layer, and transmits the data packet. In addition to the low-delay request, the transmission device 11 also includes information indicating the configuration of the block ACK to be used (for example, information for specifying the format to be used from the above cases 1 and 2, modified examples 1 and 2). The data is encapsulated and transmitted to the receiving device 12. The receiving device 12 interprets the message stored in the management action frame, and switches the process according to the presence or absence of a low delay request.

  In addition, the reception device 12 executes processing corresponding to the message only for traffic with the transmission device 11 that has transmitted the message. For example, suppose that the transmission device 11 (A) and the transmission device 11 (B) exist in the system. And when the message which stored the low delay request | requirement which requests | requires invalidation of a reorder process is received from the transmission apparatus 11 (A), the reception apparatus 12 is limited only to the traffic between transmission apparatuses 11 (A), Disable reorder processing. In addition, when sending a message, a method of specifying a traffic that invalidates the reorder processing by TID is also conceivable. If this method is used, it is not necessary to invalidate the reorder process for traffic that does not require a low delay process, and the range to which the invalidation of the reorder process is applied can be appropriately limited.

  When using the management action frame, for example, by setting “127” in the “Category” field, it becomes possible to make the frame unique to the vendor. For example, a “Message” field present after the OUI (Organizationally Unique Identifier) used to identify a vendor can be used as a field for storing a low-delay request or the like.

  Further, as a frame for describing a message, for example, a data frame having a configuration as shown in FIG. 25 can be used. In this case, for example, the transmission device 11 stores the message in the subsequent stage of the LLC-SNAP header and transmits the message to the reception device 12. The portion located at the latter stage of the LLC-SNAP header is a portion read by the upper layer. Therefore, the message is encapsulated by storing the message in the subsequent stage of the LLC-SNAP header.

(2-3-3: Notification of low-delay request using header information)
Next, a low delay request notification method using header information will be described with reference to FIGS. FIG. 26 is an explanatory diagram showing a detailed configuration of a data frame (including an IP header). On the other hand, FIG. 27 is an explanatory diagram showing a detailed configuration of a data frame (including an RTP header).

  Here, a method for detecting a low delay request by interpreting header information of data transmitted from the transmission device 11 instead of detecting a low delay request before data is transmitted from the transmission device 11 will be introduced. This method prepares a field for storing information indicating the presence or absence of a low-delay request in the header part used in the upper layer, and interprets the information set in this field to detect a low-delay request. Is to do.

  For example, as shown in FIG. 26, the “Type Of Service” field and the “Protocol” field of the IP header are used in combination. Specifically, when information indicating a low-latency request is set in the “Type Of Service” field and a value indicating UDP is set in the “Protocol” field, the receiving apparatus 12 disables reorder processing. Judge that it is required.

  Note that a MAC address or TID for designating a transmission source may be used to limit the range to which the reorder processing invalidation is applied. For example, a method is conceivable in which a MAC address or TID is detected from a packet in which a low delay request is detected, and the application range is limited by the MAC address or TID. In addition, as shown in FIG. 27, a method of storing information indicating a low delay request in the “Payload Type” field of the RTP header is also conceivable.

  The embodiment of the present technology has been described above.

<3: Summary>
Finally, the technical idea of this embodiment will be briefly summarized. The technical ideas described below include various communication functions such as PCs, mobile phones, game machines, information terminals, information appliances, video equipment, set-top boxes, recording / playback devices, music players, car navigation systems, etc. It can be applied to the information processing apparatus (communication apparatus).

  The functional configuration of the above communication apparatus can be expressed as follows. For example, the communication device described in (1) below has a configuration in which a response packet is transmitted to the transmission side at the timing when two or more packets are received. When this configuration is applied, it is possible to improve the throughput as much as overhead is reduced, compared to a configuration in which a response packet is transmitted for each packet. Further, the communication device described in (1) below transfers a packet in which no error has occurred to an upper layer without performing reorder processing. Therefore, it is possible to reduce the possibility that the data packet will expire due to a delay caused by the reorder process.

  Further, in the communication device described in the following (1), an error has occurred in all packets received before the last packet among the packets in which no error has occurred in the packet group. A response packet indicating that there is no response. For example, consider a case where the second packet is lost when receiving a packet group including four packets. In this case, the communication device described in (1) below transmits a response packet indicating that no error has occurred in the first to fourth packets to the transmission side. Therefore, the transmission side does not retransmit the missing second packet.

  However, the missing second packet is restored by the error correction unit. Therefore, the first to fourth packets are input to the upper layer application. In addition, since retransmission processing for the second packet does not occur, higher transmission efficiency is realized. As described above, it is possible to improve the throughput by devising the timing for transferring the data packet to the upper layer (invalidation of reorder processing), the transmission timing of the response packet, and the configuration of the response packet.

(1)
A receiver for receiving the packet;
A response transmission unit that transmits a response packet including information on a packet in which an error has occurred in the packet group to the transmission side each time a packet group including two or more packets is received;
A packet transfer unit that transfers a packet in which no error has occurred to an upper layer;
An error correction unit for restoring data of a packet in which an error has occurred using data of a packet in which the error has not occurred;
With
The response transmitter is
Among the packets in which no error has occurred in the packet group, the packet received last by the receiving unit is detected, and no error has occurred for all packets received before the detected packet. Send a response packet indicating that
Communication device.

(2)
The response transmitter is
When a low delay process is not requested from the upper layer, a response packet including information on all packets in which an error has occurred in the packet group is transmitted,
When low delay processing is requested from the upper layer, a packet received last by the receiving unit among the packets in which no error has occurred in the packet group is detected, and a packet before the detected packet is detected. Send a response packet indicating that no error has occurred for all packets received in
The communication device according to (1) above.

(3)
The response transmission unit includes, after the completion of the restoration process by the error correction unit, information that requests not to retransmit a packet that has been successfully restored by the error correction unit, and transmits the information to the transmission side. ,
The communication device according to (1) or (2) above.

(4)
When a packet having the same content as the packet whose data is restored by the error correction unit is retransmitted from the transmission side, a duplicate packet discard unit that discards the packet is further provided.
The communication device according to any one of (1) to (3) above.

(5)
The low-delay processing request is issued by the upper layer in response to a user operation.
The communication device according to (2) above.

(6)
The low-delay processing request is issued by the upper layer in response to a predetermined request message transmitted from the transmission side.
The communication device according to (2) above.

(7)
The predetermined request message is stored and transmitted in a data packet read in the upper layer,
The communication device according to (6) above.

(8)
The low-delay processing request is issued by the upper layer when it is determined that low-delay processing is necessary based on header information of a packet transmitted from the transmission side.
The communication device according to (2) above.

(9)
Transferring a packet in which no error has occurred among received packets to an upper layer;
Restoring data of a packet in which an error has occurred using data of a packet in which the error has not occurred;
Each time a packet group including two or more packets is received, a step of transmitting a response packet including information on a packet in which an error has occurred in the packet group to the transmission side;
Including
The transmitting step includes
A response indicating that an error has not occurred in all packets received before the detected packet is detected among the packets in which no error has occurred in the packet group. Sending a packet,
Communication method.

(10)
A transmitter for transmitting packets;
Based on information included in the response packet received from the receiving device, a retransmission control unit that causes the transmission unit to retransmit the packet in which an error has occurred,
A transmitting device having:
A receiver for receiving the packet;
A response transmission unit that transmits a response packet including information on a packet in which an error has occurred in the packet group to the transmission side each time a packet group including two or more packets is received;
A packet transfer unit that transfers a packet in which no error has occurred to an upper layer;
An error correction unit for restoring data of a packet in which an error has occurred using data of a packet in which the error has not occurred;
A receiving device;
Including
The response transmitter is
Among the packets in which no error has occurred in the packet group, the packet received last by the receiving unit is detected, and no error has occurred for all packets received before the detected packet. Send a response packet indicating that
Communications system.

(Remarks)
The receiving device 12 is an example of a communication device. The wireless interface 121 is an example of a receiving unit. The transmission processing unit 122 is an example of a response transmission unit, a packet transfer unit, and a duplicate packet discard unit. The data processing unit 124 is an example of an error correction unit. The wireless interface 114 is an example of a transmission unit. The transmission processing unit 113 is an example of a retransmission control unit.

  The preferred embodiments according to the present technology have been described above with reference to the accompanying drawings, but it is needless to say that the present technology is not limited to the configuration examples disclosed herein. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present technology. Understood.

  For example, in the above description, the wireless communication between the AP and the STA is taken as an example, but the combination of communication devices is not limited to this. The data transmission direction may be either uplink or downlink. Furthermore, the technology according to the present embodiment can be applied to communication forms such as a direct link and an ad hoc network.

DESCRIPTION OF SYMBOLS 5 Communication network 10 Communication system 11 Transmission apparatus 111 Wired interface 112 Data processing part 113 Transmission processing part 114 Wireless interface 12 Reception apparatus 121 Wireless interface 122 Transmission processing part 123 Storage part 124 Data processing part

Claims (10)

A receiver for receiving the packet;
A response transmission unit that transmits a response packet including information on a packet in which an error has occurred in the packet group to the transmission side each time a packet group including two or more packets is received;
A packet transfer unit that transfers a packet in which no error has occurred to an upper layer;
An error correction unit for restoring data of a packet in which an error has occurred using data of a packet in which the error has not occurred;
With
The response transmitter is
Among the packets in which no error has occurred in the packet group, the packet received last by the receiving unit is detected, and no error has occurred for all packets received before the detected packet. Send a response packet indicating that
Communication device. The response transmitter is
When a low delay process is not requested from the upper layer, a response packet including information on all packets in which an error has occurred in the packet group is transmitted,
When low delay processing is requested from the upper layer, a packet received last by the receiving unit among the packets in which no error has occurred in the packet group is detected, and a packet before the detected packet is detected. Send a response packet indicating that no error has occurred for all packets received in
The communication apparatus according to claim 1. The response transmission unit includes, after the completion of the restoration process by the error correction unit, information that requests not to retransmit a packet that has been successfully restored by the error correction unit, and transmits the information to the transmission side. ,
The communication apparatus according to claim 1. When a packet having the same content as the packet whose data is restored by the error correction unit is retransmitted from the transmission side, a duplicate packet discard unit that discards the packet is further provided.
The communication apparatus according to claim 1. The low-delay processing request is issued by the upper layer in response to a user operation.
The communication apparatus according to claim 2. The low-delay processing request is issued by the upper layer in response to a predetermined request message transmitted from the transmission side.
The communication apparatus according to claim 2. The predetermined request message is stored and transmitted in a data packet read in the upper layer,
The communication apparatus according to claim 6. The low-delay processing request is issued by the upper layer when it is determined that low-delay processing is necessary based on header information of a packet transmitted from the transmission side.
The communication apparatus according to claim 2. Transferring a packet in which no error has occurred among received packets to an upper layer;
Restoring data of a packet in which an error has occurred using data of a packet in which the error has not occurred;
Each time a packet group including two or more packets is received, a step of transmitting a response packet including information on a packet in which an error has occurred in the packet group to the transmission side;
Including
The transmitting step includes
A response indicating that an error has not occurred in all packets received before the detected packet is detected among the packets in which no error has occurred in the packet group. Sending a packet,
Communication method. A transmitter for transmitting packets;
Based on information included in the response packet received from the receiving device, a retransmission control unit that causes the transmission unit to retransmit the packet in which an error has occurred,
A transmitting device having:
A receiver for receiving the packet;
A response transmission unit that transmits a response packet including information on a packet in which an error has occurred in the packet group to the transmission side each time a packet group including two or more packets is received;
A packet transfer unit that transfers a packet in which no error has occurred to an upper layer;
An error correction unit for restoring data of a packet in which an error has occurred using data of a packet in which the error has not occurred;
A receiving device;
Including
The response transmitter is
Among the packets in which no error has occurred in the packet group, the packet received last by the receiving unit is detected, and no error has occurred for all packets received before the detected packet. Send a response packet indicating that
Communications system.

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