JP4367706B2 - Wireless transmission method, wireless transmitter, and wireless LAN system - Google Patents

Description

  The present invention relates to a wireless transmitter that performs wireless transmission using a wireless packet.

  In recent years, a high speed of 100 Mbit / s class is required in a wireless LAN. As a method for achieving high-speed wireless LAN, a method using a MIMO scheme using a plurality of antennas in a transceiver is promising.

  When this MIMO scheme is used, as shown in FIG. 31, the transmission speed of the DATA section is improved, but when a certain amount of information is transmitted per one wireless packet, the preamble section depends on the number of transmitting antennas. Since the length becomes longer and the DATA portion becomes shorter as the transmission speed is improved, the ratio used for data transmission decreases with time. That is, there is a problem that the data transmission efficiency deteriorates. As described above, in the case of using the MIMO scheme, the fact that the preamble portion becomes longer according to the number of transmission antennas is also described in JP-A Nos. 2002-374224 and 2003-060604.

  Therefore, in a wireless LAN to which the MIMO scheme is applied, as shown in FIG. 32, a method for increasing data transmission efficiency by concatenating and transmitting a plurality of PSDUs with one wireless packet is being studied. Similarly to the above example, Japanese Patent Laid-Open No. 2003-324445 also proposes a method of concatenating a plurality of MSDUs (MAC Service Data Units) and performing transmission as one MPDU (MAC Protocol Data Unit).

  Here, as shown in FIG. 33, for “PSDU” and “MSDU”, as described in IEEE Std 802.11a-1999, which is the IEEE 802.11a specification, the unit of data input to the MAC is MSDU. Called, encrypted, and then added with a MAC header and CRC (Cyclic Redundancy Check, or FCS (Frame Check Sequence)) are called MPDUs, and those output to PHY are called PSDUs. After scrambling and error correction code processing for this PSDU, adding a preamble and signal fields (including information such as modulation scheme) necessary for demodulation, modulating, and making it possible to transmit to a wireless medium (Hereinafter, this is referred to as a “wireless packet”.) Signal transmission shall be performed. A group of data constituting such a wireless packet is referred to as a data unit.

  The configuration of “MAC” in IEEE 802.11e, which is one of the wireless LAN standards, is as follows. As shown in FIG. 34, input data to the MAC 310 is accumulated in the buffer 311, and data belonging to an appropriate AC (Access Category) is output from the buffer 311 at an appropriate timing according to an instruction from the scheduler 312. This output data is encrypted by the encryption unit 313, then the MAC Header is added by the MAC Header addition unit 314, the frame check sequence is added by the FCS addition unit 315, and then the data is output to the PHY. . The controller 316 performs control signal processing and control of each block. The scheduler 312 controls each block according to a timer.

  The buffer 311 is configured as shown in FIG. DATA input to the buffer 311 is accumulated in queues 311b to 311e prepared for each AC by the MCA unit 311a that performs mapping processing for each Access Category. When a signal indicating that transmission is possible is input from the scheduler 312 shown in FIG. 34, the data accumulated in each of these queues competes with the operation of each of the CSMA / CAs 311f to 311i, and then multiple queues are transmitted by the Internal Collision Resolution 311k. If the timing overlaps, the higher priority is transmitted. Note that the details of the operation are as described in IEEE P802.11e / D6.0 November 2003. The data stored in the queues 311b to 311e are deleted after the reception success is confirmed by ACK. The AC described here indicates a QoS class such as Best Effort, Video Probe, Video, and Voice.

Next, the operation of the buffer 311 will be described using the flowchart shown in FIG. First, when data is input to the buffer 311 (step F1), the input data is distributed to a queue prepared for each AC (step F2). Next, the transmission data whose reception success is confirmed by the ACK is deleted from the queue (step F3), and it is determined whether or not a transmittable signal is received from the scheduler (step F4). If no transmittable signal is received from the scheduler, the process proceeds to step F1. If a transmittable signal is received from the scheduler, the CSMA / CA operation is performed for each queue to select transmission data (step F5). . Thereafter, the data selected in step F5 is transmitted (step F6), and the process proceeds to step F1.
JP 2002-374224 JP 2003-060604 A JP 2003-324445 A IEEE Std 802.11a-1999 IEEE P802.11e / D6.0 November 2003

  However, when a plurality of MSDUs are concatenated as in the prior art, it is necessary to store many MSDUs in a buffer before the packet is transmitted to the wireless medium. Therefore, as shown in FIG. Has the disadvantage of becoming larger. That is, as shown in FIG. 37, when there is one MSDU, there is no need to store the MSDU in the buffer, so the processing delay is small, but when multiple MSDUs are connected, many MSDUs are buffered. Therefore, the processing delay becomes large. In particular, for transmission such as streaming that greatly affects transmission quality, it is necessary to minimize the transmission delay. In order to reduce the transmission delay, it is indispensable to determine the number of connected MSDUs in consideration of QoS (Quality of Service).

  The present invention has been made in view of such circumstances, and a wireless transmission method, a wireless transmitter, and a wireless transmitter capable of improving transmission efficiency by determining the number of MSDU connections in consideration of QoS. An object is to provide a LAN system.

  (1) In order to achieve the above object, the present invention has taken the following measures. That is, in the wireless transmission method according to the present invention, a plurality of queues assigned corresponding to a communication partner's wireless communication device and QoS class, and the number of data units accumulated in each of the queues are combined into one wireless packet. It is determined whether or not a threshold value (yi) defined as the number of included data units has been exceeded, and if the accumulated data units in any of the queues exceed the threshold value, the accumulated data units are output. It is a feature.

  As described above, the number of data units accumulated in a plurality of queues assigned in correspondence with the wireless communication device of the communication partner and the QoS class exceeds the threshold set as the number of data units included in one wireless packet. In this case, since the accumulated data unit is output, it is possible to include a plurality of data units accumulated for each communication partner wireless communication device and QoS class in one wireless packet. As a result, it is possible to efficiently connect the data units for each wireless communication device and QoS class of the communication partner.

  (2) Further, the wireless transmission method according to the present invention performs error correction coding for each data unit based on data unit length information indicating the length of each input data unit, and the error correction coding. It is characterized by connecting each subsequent data unit.

  With this configuration, it is possible to efficiently generate one wireless packet by connecting a plurality of data units. Further, since error correction encoding is performed for each data unit, the error correction code can be terminated for each data packet, and it is possible to make it difficult for error propagation to occur between data packets.

  (3) In addition, the wireless transmission method according to the present invention determines a threshold value (yi) defined as the number of data units included in one wireless packet based on QoS parameters defined for each application of different QoS classes. It is characterized by that.

  Thus, since the threshold value is determined in consideration of QoS, the number of data units included in one wireless packet can be determined according to QoS, and it is possible to improve transmission efficiency or eliminate transmission delay. Become.

  (4) In addition, the wireless transmission method according to the present invention includes a QoS parameter defined for each application having a different QoS class, and retransmission of a retransmission data unit in standby for each application having a different QoS class and a wireless communication device of a communication partner. A threshold (yi) determined as the number of data units included in one wireless packet is determined based on the number of times.

  In this way, since the threshold value is determined in consideration of not only the QoS parameter but also the number of retransmissions of the retransmission data unit waiting for transmission, the transmission delay can be reduced.

  (5) In the wireless transmission method according to the present invention, a threshold (yi) determined as the number of data units included in one wireless packet is determined based on a QoS parameter defined for each application having a different QoS class. The numerical value obtained by adding the number of waiting retransmission data units (pi) for each application and the communication partner wireless communication device with different QoS classes to the threshold value (yi) is obtained as one wireless packet. It is characterized by the number of data units included.

  Thus, a threshold value is determined from the QoS parameters determined as described above, and the threshold value is obtained by adding the number of waiting retransmission data units for each application and communication partner wireless communication device having a different QoS class. Since the obtained numerical value is the number of data units included in one wireless packet, it is possible to improve transmission efficiency and reduce transmission delay.

  (6) In the wireless transmission method according to the present invention, a threshold (yi) determined as the number of data units included in one wireless packet is determined based on a QoS parameter defined for each application having a different QoS class. When the maximum number of retransmissions (mi) of waiting retransmission data units for each application and communication partner wireless communication device with different QoS classes is 0, the number of data units included in one wireless packet is While the determined threshold value is set, the threshold value is set to 0 when the maximum number of retransmissions (mi) of the waiting retransmission data unit for each application and communication partner wireless communication device with different QoS classes is not 0. It is characterized by that.

  In this way, when the maximum number of retransmissions of waiting retransmission data units for each application and communication partner wireless communication device with different QoS classes is not 0, that is, when there are data units to be retransmitted, Since the threshold value is set to 0 and only one retransmission data unit is included in one wireless packet, the transmission delay can be reduced.

  (7) In the wireless transmission method according to the present invention, the threshold is decreased as the maximum number of retransmissions of the data unit is increased, and the threshold is increased as the maximum number of retransmissions of the data unit is decreased. It is characterized by.

  In this way, when the maximum number of retransmissions of the data unit is large and transmission delay becomes a problem, it is possible to eliminate the transmission delay by prioritizing the cancellation of the transmission delay over the transmission efficiency and reducing the threshold. . On the other hand, when the maximum number of retransmissions of the data unit is small and transmission delay is not a problem, it is possible to improve transmission efficiency by increasing the threshold value.

  (8) In the wireless transmission method according to the present invention, the QoS parameter includes an allowable delay time, an average data rate of data input to the MAC unit, and an average value of data size input to the MAC unit. The feature is that the application is acceptable.

  Thus, the threshold can be determined according to the allowable delay time, the average data rate of the data input to the MAC unit, and the average value of the data size input to the MAC unit. It is possible to improve or eliminate transmission delay.

  (9) A wireless transmitter according to the present invention includes a MAC unit that performs transmission control, and an electrical conversion and mechanical operation for sending data output from the MAC unit to a communication line. A wireless transmitter that performs wireless transmission using a wireless packet including a plurality of data units, and a wireless transmission unit that converts data output from the PHY unit into a wireless signal and transmits the wireless signal from a transmission antenna Thus, a plurality of queues assigned corresponding to the wireless communication device of the communication partner and the QoS class, and the number of data units stored in each queue are determined as the number of data units included in one wireless packet. A determination unit that determines whether or not the threshold value (yi) has been exceeded, and as a result of the determination, the number of data units accumulated in any one of the queues exceeds the threshold value (yi) If, it is characterized in that it comprises an output control unit which controls to output data units accumulated for that queue, the.

  As described above, the number of data units accumulated in a plurality of queues assigned in correspondence with the wireless communication device of the communication partner and the QoS class exceeds the threshold set as the number of data units included in one wireless packet. In this case, since the accumulated data unit is output, it is possible to include a plurality of data units accumulated for each communication partner wireless communication device and QoS class in one wireless packet. As a result, it is possible to efficiently connect the data units for each wireless communication device and QoS class of the communication partner.

  (10) In addition, a wireless transmitter according to the present invention includes a MAC unit that performs transmission control, and electrical conversion and mechanical work for sending data output from the MAC unit to a communication line. A wireless transmitter that performs wireless transmission using a wireless packet including a plurality of data units, and a wireless transmission unit that converts data output from the PHY unit into a wireless signal and transmits the wireless signal from a transmission antenna A termination processing unit that performs termination processing at the time of error correction coding is provided for each data unit based on the input data unit length information indicating the length of each data unit.

  Thus, since termination processing at the time of error correction code is performed for each data unit, a plurality of data units can be connected to efficiently generate one wireless packet. Thereby, it is possible to make it difficult for error propagation to occur between data packets.

  (11) A wireless transmitter according to the present invention includes a MAC unit that performs transmission control, and electrical conversion and mechanical work for sending data output from the MAC unit to a communication line. A wireless transmitter that performs wireless transmission using a wireless packet including a plurality of data units, and a wireless transmission unit that converts data output from the PHY unit into a wireless signal and transmits the wireless signal from a transmission antenna A MAC control unit that determines a threshold value (yi) defined as the number of data units included in one wireless packet based on a QoS parameter defined for each application having a different QoS class is provided.

  Thus, since the threshold value is determined in consideration of QoS, the number of data units included in one wireless packet can be determined according to QoS, and it is possible to improve transmission efficiency or eliminate transmission delay. Become.

  (12) A wireless transmitter according to the present invention includes a MAC unit that performs transmission control, and an electrical conversion and mechanical operation for sending data output from the MAC unit to a communication line. A wireless transmitter that performs wireless transmission using a wireless packet including a plurality of data units, and a wireless transmission unit that converts data output from the PHY unit into a wireless signal and transmits the wireless signal from a transmission antenna Based on the QoS parameters determined for each application of different QoS classes, and the number of retransmissions of the waiting retransmission data unit for each wireless communication device of the communication partner and the different QoS class, It is characterized by including a MAC control unit for determining a threshold value (yi) defined as the number of data units included.

  In this way, since the threshold value is determined in consideration of not only the QoS parameter but also the number of retransmissions of the retransmission data unit waiting for transmission, the transmission delay can be reduced.

  (13) In the wireless transmitter according to the present invention, the MAC control unit may determine a threshold value defined as the number of data units included in one wireless packet based on a QoS parameter defined for each application having a different QoS class. (yi) is determined, and a numerical value obtained by adding the number (pi) of retransmission data units in standby for each of the wireless communication devices of different applications and communication counterparts to the threshold (yi) , The number of data units included in one wireless packet.

  Thus, a threshold value is determined from the QoS parameters determined as described above, and the threshold value is obtained by adding the number of waiting retransmission data units for each application and communication partner wireless communication device having a different QoS class. Since the obtained numerical value is the number of data units included in one wireless packet, it is possible to improve transmission efficiency and reduce transmission delay.

  (14) In the wireless transmitter according to the present invention, the MAC control unit may determine a threshold value defined as the number of data units included in one wireless packet based on a QoS parameter defined for each application having a different QoS class. (yi) is determined and included in one wireless packet when the maximum number of retransmissions (mi) of the waiting retransmission data unit for each application and communication partner wireless communication device with different QoS classes is 0 If the maximum number of retransmissions (mi) of waiting retransmission data units for each application and communication partner wireless communication device is not 0, while the number of data units to be determined is the determined threshold value, The threshold value is set to 0.

  In this way, when the maximum number of retransmissions of waiting retransmission data units for each application and communication partner wireless communication device with different QoS classes is not 0, that is, when there are data units to be retransmitted, Since the threshold value is set to 0 and only one retransmission data unit is included in one wireless packet, the transmission delay can be reduced.

  (15) In the wireless transmitter according to the present invention, the MAC control unit decreases the threshold as the maximum number of retransmissions of the data unit increases, and decreases the maximum number of retransmissions of the data unit. The threshold value is increased.

  In this way, when the maximum number of retransmissions of the data unit is large and transmission delay becomes a problem, it is possible to eliminate the transmission delay by prioritizing the cancellation of the transmission delay over the transmission efficiency and reducing the threshold. . On the other hand, when the maximum number of retransmissions of the data unit is small and transmission delay is not a problem, it is possible to improve transmission efficiency by increasing the threshold value.

  (16) In the wireless transmitter according to the present invention, the QoS parameter includes an allowable delay time, an average data rate of data input to the MAC unit, and an average value of the data size input to the MAC unit. It is characterized in that the application is acceptable.

  Thus, the threshold can be determined according to the allowable delay time, the average data rate of the data input to the MAC unit, and the average value of the data size input to the MAC unit. It is possible to improve or eliminate transmission delay.

  (17) Further, an access point according to the present invention includes any one of the wireless transmitters described above.

  According to this access point, the number of data units stored in a plurality of queues assigned in correspondence with the wireless communication device of the communication partner and the QoS class is determined as the number of data units included in one wireless packet. Since the accumulated data unit is output when the threshold value is exceeded, it is possible to include a plurality of data units accumulated for each communication partner wireless communication device and QoS class in one wireless packet. As a result, it is possible to efficiently connect the data units for each wireless communication device and QoS class of the communication partner. In addition, since the threshold value is determined in consideration of QoS, the number of data units included in one wireless packet can be determined according to QoS, and it is possible to improve transmission efficiency or eliminate transmission delay.

  (18) A station according to the present invention includes any one of the wireless transmitters described above.

  According to this station, the number of data units stored in a plurality of queues assigned to correspond to the wireless communication device of the communication partner and the QoS class is a threshold defined as the number of data units included in one wireless packet. Since the accumulated data unit is output when the number exceeds, it is possible to include a plurality of data units accumulated for each communication partner wireless communication device and QoS class in one wireless packet. As a result, it is possible to efficiently connect the data units for each wireless communication device and QoS class of the communication partner. In addition, since the threshold value is determined in consideration of QoS, the number of data units included in one wireless packet can be determined according to QoS, and it is possible to improve transmission efficiency or eliminate transmission delay.

  (19) Further, a wireless LAN system according to the present invention is characterized by comprising the above-mentioned access point and the above-mentioned station.

  According to this wireless LAN system, the number of data units stored in a plurality of queues assigned corresponding to the wireless communication device of the communication partner and the QoS class is determined as the number of data units included in one wireless packet. Since the accumulated data unit is output when the threshold value is exceeded, it is possible to include a plurality of data units accumulated for each communication partner wireless communication device and QoS class in one wireless packet. As a result, it is possible to efficiently connect the data units for each wireless communication device and QoS class of the communication partner. In addition, since the threshold value is determined in consideration of QoS, the number of data units included in one wireless packet can be determined according to QoS, and it is possible to improve transmission efficiency or eliminate transmission delay.

  (20) Further, an image transmission apparatus according to the present invention includes any one of the wireless transmitters described above.

  According to this image transmission apparatus, the number of data units stored in a plurality of queues assigned in correspondence with the wireless communication device of the communication partner and the QoS class is determined as the number of data units included in one wireless packet. Since the accumulated data unit is output when the threshold value is exceeded, it is possible to include a plurality of data units accumulated for each communication partner wireless communication device and QoS class in one wireless packet. As a result, it is possible to efficiently connect the data units for each wireless communication device and QoS class of the communication partner. In addition, since the threshold value is determined in consideration of QoS, the number of data units included in one wireless packet can be determined according to QoS, and it is possible to improve transmission efficiency or eliminate transmission delay.

  (21) Further, a tuner according to the present invention is characterized by including any one of the wireless transmitters described above.

  According to this tuner, the threshold value defined as the number of data units included in one wireless packet is the number of data units stored in a plurality of queues assigned corresponding to the wireless communication device of the communication partner and the QoS class. Since the accumulated data unit is output when the number exceeds, it is possible to include a plurality of data units accumulated for each communication partner wireless communication device and QoS class in one wireless packet. As a result, it is possible to efficiently connect the data units for each wireless communication device and QoS class of the communication partner. In addition, since the threshold value is determined in consideration of QoS, the number of data units included in one wireless packet can be determined according to QoS, and it is possible to improve transmission efficiency or eliminate transmission delay.

  According to the present invention, since the threshold value is determined in consideration of QoS, the number of data units included in one wireless packet can be determined according to QoS, and transmission efficiency can be improved or transmission delay can be eliminated. It becomes possible.

  In addition, when the number of data units stored in a plurality of queues assigned to correspond to the wireless communication device of the communication partner and the QoS class exceeds a threshold set as the number of data units included in one wireless packet In addition, since the accumulated data unit is output, it is possible to include a plurality of data units accumulated for each communication partner wireless communication device and QoS class in one wireless packet. As a result, it is possible to efficiently connect the data units for each wireless communication device and QoS class of the communication partner.

(First embodiment)
FIG. 1 is a diagram illustrating a schematic configuration of a wireless transmitter according to the first embodiment. The wireless transmitter 1 performs transmission control in the MAC 10 unit. Data output from the MAC unit 10 is input to the PHY unit 20, and the PHY unit 20 performs electrical conversion and mechanical work for sending the data to the communication line. Data output from the PHY unit 20 is converted into a radio signal by the radio transmission unit (RF) 30 and transmitted from the transmission antenna 40. The wireless transmitter 1 performs wireless transmission using a wireless packet including a plurality of data units.

  In the wireless transmitter 1 according to the first embodiment, the MAC unit 10 adopts a configuration as shown in FIG. That is, input data to the MAC unit 10 is accumulated in the buffer 11, and data belonging to an appropriate AC (Access Category) is output from the buffer 11 at an appropriate timing according to an instruction from the scheduler 12. Then, after the data output from the buffer 11 is encrypted by the encryption unit 13, the MAC header addition unit 14 adds the MAC header. After that, the Frame Check Sequence is added by the FCS adding unit 15 and outputted to the PHY.

  In FIG. 2, the controller 16 processes the control signal and controls each block, determines the number “yi” of MSDUs to be connected, and notifies the buffer 11. The scheduler 12 controls each block according to a timer. The controller 16 described above constitutes a MAC control unit.

  Next, the buffer 11 in the MAC unit 10 will be described. FIG. 3 is a diagram illustrating a schematic configuration of the buffer 11. The DATA input to the buffer 11 is mapped by Mapping to AC / STA 11a according to the AC and the STA (station) destined for transmission, and accumulated in the queues 11b to 11e prepared for each AC and STA. That is, data destined for different STAs are accumulated in different queues, and data belonging to different ACs destined for the same STA is accumulated in different queues.

  When a signal indicating that transmission is possible is input from the scheduler 12, a queue in which “yi” or more data is accumulated among these queues 11b to 11e competes by the operation of the CSMA / CA 11f to 11i. Here, “yi” and “i” are natural numbers, and indicate that an i-th queue in which at least yi pieces of data are accumulated is a candidate for a transmission signal.

  Next, after the above competition, when the transmission timings of a plurality of queues overlap with each other by the Internal Collation Resolution 11k, the higher priority is transmitted. The data stored in the queues 11b to 11e are deleted after the reception success is confirmed by ACK. Yi determines the number of MSDUs to be linked in one radio packet determined for each of the queues 11b to 11e.

  Next, in FIG. 4, the internal operation of the queues 11b to 11e shown in FIG. 3 will be described. The queues 11 b to 11 e are stored in the memory 11-1 according to the memory 11-1, the determination unit 11-2 that determines whether or not the threshold value yi is exceeded, and the determination result of the determination unit 11-2 An output control unit 11-3 that performs output control and a control unit 11-4 that performs deletion of memory contents and the like in accordance with instructions from the controller 11. These do not need to be configured by hardware, and may be configured by a memory, a CPU, and software.

  Next, the operation of the buffer 11 will be described. Here, as shown in FIG. 5, it is assumed that data is transmitted from an AP (base station) 40 to two STAs (terminals: stations) STA1 (41) and STA2 (42).

  FIG. 6 is a flowchart showing the operation of the buffer 11. First, when data is input to the buffer 11 (step S1), the input data is distributed to a queue prepared for each AC and STA (step S2). Subsequently, the transmission data whose reception success is confirmed by the ACK is deleted from the queue (step S3), and it is determined whether or not a transmittable signal has been received from the scheduler (scheduler 12) (step S4). In step S4, if a transmittable signal has not been received from the scheduler, the process proceeds to step S1. If a transmittable signal has been received from the scheduler, the queue in which yi or more data is accumulated is stored in each queue. CA operation is performed to select transmission data (step S5). Then, the data selected in step S5 is transmitted (step S6), and the process proceeds to step S1.

  By performing these operations in the buffer 11, as shown in FIG. 7A, the MSDUs for the STA1 (41) and the STA2 (42) input to the MAC unit 10 are connected by y1 and y2, respectively. It is output from the buffer 11. As a result, as shown in FIG. 7 (b), wireless packets in which y1 and y2 PSDUs are concatenated are transmitted to STA1 (41) and STA2 (42), respectively.

  In FIG. 7, numbers are added in the form of MSDU # n-m or PSDU # n-m, where n is data addressed to STAn. m represents the m-th data. Accordingly, FIG. 7 shows that MSDU is buffered for each destination terminal, and one wireless packet is transmitted by concatenating MSDU (or PSDU) addressed to the same STA. Here, y1 and y2 indicate that y1 MSDUs are concatenated and transmitted to STA1, and y2 MSDUs are concatenated and transmitted to STA2.

  Next, the PHY unit 20 in FIG. 1 will be described. FIG. 8 is a diagram illustrating a schematic configuration of the PHY unit 20. As illustrated in FIG. 8, the PHY unit 20 performs error correction coding on the data output from the MAC unit 10 in units of PSDU in the FEC encoder 21. That is, in the FEC encoder 21, as shown in FIG. 9, “tail bit” is added at the end of each PSDU, and the error correction code is terminated for each PSDU. Then, a plurality of C-PSDUs are created and output to the modulator 22. The output from the modulator 22 is output to the IFFT 23, and the output from the IFFT 23 is output to the filter 24. The signal output from the filter 24 is converted into a radio signal by the radio transmission unit (RF) 30 and transmitted from the transmission antenna 40.

  At this time, from the MAC unit 10 to the controller 25 of the PHY 20, as shown in FIG. 9, length (total number of bits of PSDU after concatenation), PSDU # 1 length (number of bits of PSDU # 1), PSDU It is assumed that # 2 length (number of bits of PSDU # 2) and PSDU # 3 length (number of bits of PSDU # 3) are output. The FEC encoder 21 instructs the tail bit insertion position from the controller 25 based on PSDU # 1 length, PSDU # 2 length, and PSDU # 3 length. The controller 25 controls each block based on the length and connects a plurality of PSDUs to create one wireless packet.

  Next, the internal operation of the FEC encoder 21 will be described with reference to FIG. The FEC encoder 21 inserts tail bits, that is, a termination processing unit 21a that performs termination processing for error correction code, based on the above-described concatenation parameter (data unit length information), and a signal output from the termination processing unit 21a. An error correction encoding unit 21b that corrects and outputs an error is included.

  In the above, the case where three PSDUs are connected is taken as an example, but the procedure does not change even if this is the case where s (s is a natural number) PSDUs are connected.

  By configuring the PHY unit 20 in this way, it is possible to connect a plurality of MSDUs and generate one radio packet as shown in FIG. Also, terminating the error correction code for each PSDU has the effect of making it difficult for errors to propagate between PSDUs.

  On the other hand, as shown in FIG. 12, the data output from the MAC unit 10 may be error correction encoded after the PSDU is connected in the FEC encoder 21. That is, as shown in FIG. 12, in the FEC encoder 21, “tail bit” is attached only to the tail of the PSDU to be connected, one C-PSDU is created, and output to the modulator 22. The output from the modulator 22 is output to the IFFT 23, and the output from the IFFT 23 is output to the filter 24. The signal output from the filter 24 is converted into a radio signal by the radio transmission unit (RF) 30 and transmitted from the transmission antenna 40.

  At this time, as shown in FIG. 12, length (total number of bits of PSDU after concatenation) is output from the MAC unit 10 to the controller 25 of the PHY unit 20 as a concatenation parameter. In the FEC encoder 21, the tail bit insertion position is instructed from the controller 25 based on the length. The controller 25 controls each block based on the length and connects a plurality of PSDUs to create one wireless packet.

  In the above, the case where three PSDUs are connected is taken as an example, but the procedure does not change even if this is the case where s (s is a natural number) PSDUs are connected.

  By configuring the PHY unit 20 in this way, it is possible to connect a plurality of MSDUs and generate one radio packet as shown in FIG.

  Next, the configuration of the PHY unit when the MIMO scheme is applied will be described. FIG. 14 is a diagram illustrating a schematic configuration of a wireless transmitter employing the MIMO scheme. As shown in FIG. 14, the data output from the MAC unit 10 is subjected to error correction coding in the FEC encoder 21. This is output to the modulator 22, and the S / P conversion unit 120 performs S / P conversion (Serial to Parallel conversion) on the output from the modulator 22. The S / P conversion described here refers to assigning to each antenna for each OFDM symbol as shown in FIG. Subsequently, the output from the S / P converter 120 is output to the IFFTs 23a to 23c, and the output from each IFFT 23a to 23c is output to the filters 24a to 24c, respectively. And the signal output from each filter 24a-24c is each converted into a radio signal in radio | wireless transmission part (RF) 30a-30c, and is transmitted from each transmission antenna 40a-40c.

  14 is obtained by applying the MIMO scheme to the wireless transmitter shown in FIG. 8. As described above, error correction coding may be performed for each PSDU, and the concatenation may be performed. It is assumed that error correction coding may be performed on the PSDU.

(Second Embodiment)
In 2nd Embodiment, the function of the MAC part in a transmitter for connecting several MSDU is shown. Further, in the present embodiment, as shown in FIG. 16, a case where data is transmitted from the AP 40 to one STA1 (41) will be described. However, it is assumed that two TSs (Traffic Streams) are transmitted from the AP 40 to the STA1 (41). In the second embodiment, the ACs of the two TSs are different. As an example, in FIG. 16, TS # A represents data transmission for a personal computer, and TS # B represents image transmission for TV. The configuration of the MAC unit and the configuration of the PHY unit are the same as those described in the first embodiment. That is, the MAC unit employs a configuration as shown in FIG. As shown in FIG. 2, input data to the MAC unit 10 is accumulated in the buffer 11, and data belonging to an appropriate AC (Access Category) is output from the buffer 11 at an appropriate timing according to an instruction from the scheduler 12. Then, after the data output from the buffer 11 is encrypted by the encryption unit 13, the MAC header addition unit 14 adds the MAC header. After that, the Frame Check Sequence is added by the FCS adding unit 15 and outputted to the PHY.

  In FIG. 2, the controller 16 processes the control signal and controls each block, determines the number “yi” of MSDUs to be connected, and notifies the buffer 11. The scheduler 12 controls each block according to a timer.

  Further, the PHY unit adopts a configuration as shown in FIG. 8 or FIG. When the configuration shown in FIG. 8 is adopted, the PHY unit 20 performs error correction coding on the data output from the MAC unit 10 in units of PSDU in the FEC encoder 21. That is, in the FEC encoder 21, as shown in FIG. 9, “tail bit” is added at the end of each PSDU, and the error correction code is terminated for each PSDU. Then, a plurality of C-PSDUs are created and output to the modulator 22. The output from the modulator 22 is output to the IFFT 23, and the output from the IFFT 23 is output to the filter 24. The signal output from the filter 24 is converted into a radio signal by the radio transmission unit (RF) 30 and transmitted from the transmission antenna 40.

On the other hand, as shown in FIG. 12, the data output from the MAC unit 10 may be error correction encoded after the PSDU is connected in the FEC encoder 21. That is, as shown in FIG. 12, in the FEC encoder 21, “tail bit” is attached only to the tail of the PSDU to be connected, one C-PSDU is created, and output to the modulator 22. The output from the modulator 22 is output to the IFFT 23, and the output from the IFFT 23 is output to the filter 24. The signal output from the filter 24 is converted into a radio signal by the radio transmission unit (RF) 30 and transmitted from the transmission antenna 40.
Next, a case where a PHY configuration to which the MIMO scheme shown in FIG. 14 is applied will be described. As shown in FIG. 14, the data output from the MAC unit 10 is subjected to error correction coding in the FEC encoder 21. This is output to the modulator 22, and the S / P conversion unit 120 performs S / P conversion (Serial to Parallel conversion) on the output from the modulator 22. The S / P conversion described here refers to assigning to each antenna for each OFDM symbol as shown in FIG. Subsequently, the output from the S / P converter 120 is output to the IFFTs 23a to 23c, and the output from each IFFT 23a to 23c is output to the filters 24a to 24c, respectively. And the signal output from each filter 24a-24c is each converted into a radio signal in radio | wireless transmission part (RF) 30a-30c, and is transmitted from each transmission antenna 40a-40c.

  14 is obtained by applying the MIMO scheme to the wireless transmitter shown in FIG. 8, and error correction coding may be performed for each PSDU as described above. It is assumed that error correction coding may be performed on the PSDU.

  Here, as shown in FIG. 16, a case will be described in which data is transmitted from the AP 40 to one STA1 (41). However, it is assumed that two TSs (Traffic Streams) are transmitted from the AP 40 to the STA1 (41). In the second embodiment, the ACs of the two TSs are different. As an example, in FIG. 16, TS # A represents data transmission for a personal computer, and TS # B represents image transmission for TV.

  Next, the operation of the buffer 11 (see FIG. 3) in the MAC unit will be described with reference to the flowchart shown in FIG. First, when data is input to the buffer 11 (step S1), the input data is distributed to a queue prepared for each AC and STA (step S2). That is, in this embodiment, two TSs are stored in different queues because the ACs are different. Next, the transmission data whose reception success is confirmed by the ACK is deleted from the queue (step S3), and it is determined whether or not a transmittable signal has been received from the scheduler (scheduler 12) (step S4).

  In step S4, if a transmittable signal is not received from the scheduler, the process proceeds to step S1. On the other hand, if a transmittable signal is received from the scheduler, a queue in which at least yi pieces of data are accumulated is stored in each queue. CSMA / CA operation is performed to select transmission data (step S5). Thereafter, the data selected in step S5 is transmitted (step S6), and the process proceeds to step S1.

  By performing these operations in the buffer 11, as shown in FIG. 17A, the MSDUs for TS # A and B input to the MAC unit are connected by y 1 and y 2 and output from the buffer 11. Become. As a result, as shown in FIG. 17B, finally, wireless packets in which y1 and y2 PSDUs are concatenated are transmitted to TS # A and TSB, respectively. In FIG. 17, alphabets and numbers are added in the form of MSDU # q-m or PSDU # q-m, where q means data corresponding to TS # q, and m is m It shows that it is the data of the piece. Accordingly, FIG. 17 shows that MSDUs are buffered for each TS, and one wireless packet is transmitted by concatenating MSDUs (or PSDUs) of the same TS. Incidentally, y1 and y2 indicate that y1 MSDU is connected to TS # A for transmission, and y2 MSDU is connected to TS # B for transmission.

  As described above, a system with high transmission efficiency can be created by constructing a wireless LAN system by using an access point and a station including a transmitter having the configuration of the PHY unit and the MAC unit. Further, by using this wireless LAN system, it is possible to create an image transmission device capable of transmitting a high-quality moving image and a tuner for transmitting an image to a video display device.

(Third embodiment)
In 3rd Embodiment, the function of the MAC part in a transmitter for connecting several MSDU is shown. In 3rd Embodiment, the function of the MAC part in a transmitter for connecting several MSDU is shown. In this embodiment, as shown in FIG. 18, a case where data is transmitted from the AP 40 to one STA1 (41) will be described. However, it is assumed that two TSs (Traffic Streams) are transmitted from the AP 40 to the STA1 (41), and in the second embodiment, the ACs of the two TSs are the same. As an example, in FIG. 18, both TS # B and TS # C represent image transmission for TV. The configurations of the MAC unit and the PHY unit are considered to be the same as those described in the first embodiment. That is, the MAC unit employs a configuration as shown in FIG. As shown in FIG. 2, input data to the MAC unit 10 is accumulated in the buffer 11, and data belonging to an appropriate AC (Access Category) is output from the buffer 10 at an appropriate timing according to an instruction from the scheduler 12. Then, after the data output from the buffer 11 is encrypted by the encryption unit 13, the MAC header addition unit 14 adds the MAC header. After that, the Frame Check Sequence is added by the FCS adding unit 15 and outputted to the PHY.

  In FIG. 2, the controller 16 processes the control signal and controls each block, determines the number “yi” of MSDUs to be connected, and notifies the buffer 11. The scheduler 12 controls each block according to a timer.

  Further, the PHY unit has a configuration as shown in FIG. 8 or FIG. When the configuration shown in FIG. 8 is adopted, the PHY unit 20 performs error correction coding on the data output from the MAC unit 10 in units of PSDU in the FEC encoder 21. That is, in the FEC encoder 21, as shown in FIG. 9, “tail bit” is added at the end of each PSDU, and the error correction code is terminated for each PSDU. Then, a plurality of C-PSDUs are created and output to the modulator 22. The output from the modulator 22 is output to the IFFT 23, and the output from the IFFT 23 is output to the filter 24. The signal output from the filter 24 is converted into a radio signal by the radio transmission unit (RF) 30 and transmitted from the transmission antenna 40.

  On the other hand, as shown in FIG. 12, the data output from the MAC unit 10 may be error correction encoded after the PSDU is connected in the FEC encoder 21. That is, as shown in FIG. 12, in the FEC encoder 21, “tail bit” is attached only to the tail of the PSDU to be connected, one C-PSDU is created, and output to the modulator 22. The output from the modulator 22 is output to the IFFT 23, and the output from the IFFT 23 is output to the filter 24. The signal output from the filter 24 is converted into a radio signal by the radio transmission unit (RF) 30 and transmitted from the transmission antenna 40.

Next, a case where a PHY configuration to which the MIMO scheme shown in FIG. 14 is applied will be described. As shown in FIG. 14, the data output from the MAC unit 10 is subjected to error correction coding in the FEC encoder 21. This is output to the modulator 22, and the S / P conversion unit 120 performs S / P conversion (Serial to Parallel conversion) on the output from the modulator 22. The S / P conversion described here refers to assigning to each antenna for each OFDM symbol as shown in FIG. Subsequently, the output from the S / P converter 120 is output to the IFFTs 23a to 23c, and the output from each IFFT 23a to 23c is output to the filters 24a to 24c, respectively. And the signal output from each filter 24a-24c is each converted into a radio signal in radio | wireless transmission part (RF) 30a-30c, and is transmitted from each transmission antenna 40a-40c.
14 is obtained by applying the MIMO scheme to the wireless transmitter shown in FIG. 8, and error correction coding may be performed for each PSDU as described above. It is assumed that error correction coding may be performed on the PSDU.

  Here, as shown in FIG. 18, a case where data is transmitted from the AP 40 to one STA1 (41) will be described. However, it is assumed that two TSs (Traffic Streams) are transmitted from the AP 40 to the STA1 (41). In the third embodiment, the ACs of the two TSs are the same. As an example, in FIG. 18, both TS # B and TS # C represent image transmission for TV. Further, the operation of the buffer 11 (see FIG. 3) in the MAC unit is the same as the flowchart shown in FIG. 6 in the first embodiment.

  That is, as shown in FIG. 6, when data is input to buffer 11 (step S1), the input data is distributed to queues prepared for each AC and STA (step S2). That is, in this embodiment, two TSs are stored in the same queue because AC is the same. Subsequently, the transmission data whose reception success is confirmed by the ACK is deleted from the queue (step S3), and it is determined whether or not a transmittable signal has been received from the scheduler (scheduler 12) (step S4). In step S4, if a transmittable signal has not been received from the scheduler, the process proceeds to step S1, and if a transmittable signal has been received from the scheduler, a queue in which at least yi pieces of data have been accumulated is stored in each queue. CA operation is performed to select transmission data (step S5). Then, the data selected in step S5 is transmitted (step S6), and the process proceeds to step S1.

  In the third embodiment, when the buffer 11 performs the above-described operation, as shown in FIG. 19A, y MSDUs for TS # B and C input to the MAC unit are connected, and the buffer 11 Will be output. As a result, finally, as shown in FIG. 19B, a radio packet in which y PSDUs are concatenated for TS # B and C is transmitted.

  In FIG. 19, alphabets and numerals are added in the form of MSDU # q-m or PSDU # q-m, where q means data addressed to TS # q, and m is m pieces. Indicates eye data. Accordingly, FIG. 19 shows that MSDUs of TS # B and C are buffered, and MSDU (or PSDU) is concatenated and transmitted in one radio packet. Here, “y” indicates that y MSDUs are concatenated and transmitted.

  When a plurality of STAs and a plurality of TSs are mixed, the MAC unit and the PHY unit can operate by combining the first, second, and third embodiments. The operation of these combinations is derived from the first, second, and third embodiments.

(Fourth embodiment)
In the fourth embodiment, a method for determining the number of connections y when a plurality of MSDUs are connected will be described. In particular, in the fourth embodiment, y is obtained from a QoS parameter when retransmission is not considered.

  First, FIG. 20 shows a TSPEC (Traffic Specification Element) defined by IEEE 802.11e as an example of a QoS parameter. As shown in FIG. 20, in IEEE 802.11e, transmission conditions required for each TS are defined by a parameter group called TSPEC. A typical one of these will be explained. Nominal MSDU Size is “average value (unit is octet) of frame size (data size input to MAC section)”, and Mean Data Rate is “(input to MAC section). The average value of the data rate “, Delay Bound” indicates “allowable delay time (allowable by the application)”. These parameters defined by TSPEC are specified by the application.

  FIG. 21 is a flowchart illustrating a procedure in which the controller 16 in the MAC unit described with reference to FIG. 2 in the first embodiment determines the MSDU concatenation number “y” based on the QoS parameters. First, n (1 or more real number) is determined for each AC (step R1). Next, for each AC, x = Delay Bound / n [ms] is derived (step R2), and y for each AC is derived (step R3). Then, y for each AC is notified to the buffer 11 (step R4).

Next, a change in the QoS parameter is detected (step R5). If there is a change, the process proceeds to step R2, and if there is no change, the determination in step R5 is repeated. However, in the case described in the third embodiment in which a plurality of communication partner STAs and ACs have the same TS, the above-described Delay Bound,
Mean Data Rate,
Nominal MSDU Size,
Delay Bound = min (Delay Bound 1, Delay Bound 2,..., Delay Bound n),
Mean Data Rate = add (Mean Data Rate 1, Mean Data Rate 2,..., Mean Data Rate n),
Nominal MSDU Size = ave (Nominal MSDU Size1, Nominal MSDU Size2,..., Nominal MSDU Size)
It shall be represented by

“Min ()” represents a function for obtaining a minimum value of elements in parentheses, and add () represents a function for obtaining a sum of elements in parentheses. Further, ave () represents a function for obtaining an average value of elements in parentheses. Also,
Delay Bound r,
Mean Data Rater,
Nominal MSDU Size,
“allowable delay time of r-th TS (allowable by application)”,
"Average value of data rate (input to MAC) of r-th TS",
“Average value (unit: octet) of frame size (data size input to MAC) of r-th TS”. Note that r represents a natural number. In FIG. 21, y is determined for each AC. However, y may be determined for each queue prepared for each communication partner STA and AC.

An example in which the MSDU concatenation number y is determined using the above procedure is shown in FIG. 22 and FIG. In FIG.
n = 4,
Delay Bound = 1 [ms],
Nominal MSDU Size = 2000 [octet],
It is assumed that Mean Data Rate = 48M [bit / sec]. Applying these parameters to the procedure shown in FIG.
x = Delay Bound / n = 0.25 [ms],
y = Mean Data Rate * x / (Nominal MSDU Size * 8) = 3 [pieces]
And
As shown in FIG. 22, a radio packet in which three MSDUs are concatenated is transmitted every 0.25 ms.

Similarly, in FIG.
n = 2,
Delay Bound = 1 [ms],
It is assumed that Nominal MSDU Size = 2000 [octets] and Mean Data Rate = 48 M [bit / sec]. Applying these parameters to the procedure shown in FIG.
x = Delay Bound / n = 0.5 [ms],
y = Mean Data Rate * x / (Nominal MSDU Size * 8) = 6 [pieces]
And
As shown in FIG. 23, a radio packet in which six MSDUs are concatenated is transmitted every 0.5 ms.

  As described above, even with TS having the same QoS parameter, by adjusting n, it is possible to reduce the transmission delay or increase the transmission efficiency. A method of changing the value n according to the application, the PER (Packet Error Rate) of data, and the state of the propagation path is also conceivable. Further, the number y of MSDU connections is determined for each AC, but it is sufficient to apply the method shown in FIG. 21 for the procedure. In this embodiment, it is assumed that the data transmitted from the application is at a constant rate. However, the time-out process is performed based on the storage time of the data stored in the queue, so that the variable rate application is supported. In order to shorten the processing delay time, it is conceivable to change the connection number y of the MSDUs depending on the type of transmission packet (such as ACK).

(Fifth embodiment)
In the fifth embodiment, a method for determining the number of connections y when connecting a plurality of MSDUs will be described. In particular, in the fifth embodiment, y is obtained from the QoS parameters when retransmission is considered and the number of retransmissions of data stored in the queue.

  FIG. 24 is a flowchart illustrating a procedure in which the controller 16 in the MAC unit described with reference to FIG. 2 in the first embodiment determines the MSDU concatenation number y based on the QoS parameters. First, ni (1 or more real number) is determined for each queue (step P1). Next, xi = Delay Bound / ni [ms] is derived for each queue (step P2), and yi for each queue is derived (step P3). Next, it is determined whether mi is 0 or greater than 0 (step P4). If mi> 0, yi = yi + pi is set (step P5), and the process proceeds to step P6. On the other hand, if mi = 0 in step P4, the process proceeds to step P6.

  Next, the buffer 11 is notified of yi for each queue (step P6), and the change of the QoS parameter and mi is detected (step P7). repeat.

Here, ni, yi, mi, and pi are n, y (the number of connected MSDUs), m (the maximum number of retransmissions among the retransmission data stored in the queue), p (queue) in the i-th queue. The number of retransmitted data stored in the As an example of deriving “yi” in step P3,
yi = roundup (Mean Data Rate * xi / (Nominal MSDU Size * 8))
Can be considered. In the above formula, the function roundup () indicates a process of rounding up the number in parentheses to an integer.

However, in the case described in the third embodiment in which a plurality of communication partner STAs and ACs have the same TS, the above-described Delay Bound,
Mean Data Rate,
Nominal MSDU Size,
Delay Bound = min (Delay Bound 1, Delay Bound 2,..., Delay Bound n),
Mean Data Rate = add (Mean Data Rate 1, Mean Data Rate 2,..., Mean Data Rate n),
Nominal MSDU Size = ave (Nominal MSDU Size1, Nominal MSDU Size2,..., Nominal MSDU Size)
It shall be represented by

Note that min () represents a function for obtaining the minimum value of elements in parentheses, and add () represents a function for obtaining the sum of elements in parentheses. ave () represents a function for obtaining an average value of elements in parentheses. Also,
Delay Bound r,
Mean Data Rater,
Nominal MSDU Size,
“allowable delay time of r-th TS (allowable by application)”,
"Average value of data rate (input to MAC) of r-th TS",
“Average value (unit: octet) of the frame size (data size input to the MAC) of the r-th TS”.

FIG. 25 is a diagram illustrating an example in which the MSDU concatenation number y is determined using the above procedure. In FIG.
n = 4,
Delay Bound = 1 [ms], Nominal MSDU Size = 2000 [octet],
It is assumed that Mean Data Rate = 48M [bit / sec]. Also, it is assumed that PSDU # 1, PSDU # 7, and PSDU # 8 are erroneous once each. Applying these parameters to the procedure shown in FIG.
x = Delay Bound / n = 0.25 [ms],
y = Mean Data Rate * x / (Nominal MSDU Size * 8) = 3 [pieces] (when there is no retransmission),
y = 3 + p (with retransmission),
And
As shown in FIG. 22, every 0.25 ms, when there is no retransmission data, a wireless packet in which three MSDUs are concatenated, and when there is retransmission data, the retransmit MSDU and three new MSDUs are concatenated and transmitted Will do.

(Sixth embodiment)
In the sixth embodiment, a method for determining the number of connections y when connecting a plurality of MSDUs will be described. In particular, in the sixth embodiment, y is obtained from the QoS parameters when retransmission is considered and the number of retransmissions of data stored in the queue.

  FIG. 26 is a flowchart illustrating a procedure in which the controller 16 in the MAC unit described with reference to FIG. 2 in the first embodiment determines the MSDU concatenation number y based on the QoS parameters. First, ni (1 or more real number) is determined for each queue (step Q1). Next, a determination is made as to whether mi is 0 or greater than 0 (step Q2). If mi> 0, yi = 0 is set in step Q5 and the process proceeds to step Q6.

  On the other hand, if mi = 0 in step Q2, xi = Delay Bound / ni [ms] is derived for each queue (step Q3), and yi for each queue is derived (step Q4).

  Next, yi for each queue is notified to buffer 11 (step Q6), and a change in the QoS parameters and mi is detected (step Q7). If there is a change, the process proceeds to step Q2. repeat. Here, ni, yi, and mi indicate the values of n, y (the number of connected MSDUs) and m (the maximum number of retransmissions among the retransmission data stored in the queue) in the i-th queue. .

In addition, as an example of deriving yi in step Q4,
yi = roundup (Mean Data Rate * xi / (Nominal MSDU Size * 8))
Can be considered. Note that the function roundup () in the above formula indicates processing for rounding up the number in parentheses to an integer.

However, in the case described in the third embodiment where a plurality of TSs exist, the above-described Delay Bound,
Mean Data Rate,
Nominal MSDU Size,
Delay Bound = min (Delay Bound 1, Delay Bound 2,..., Delay Bound n),
Mean Data Rate = add (Mean Data Rate 1, Mean Data Rate 2,..., Mean Data Rate n),
Nominal MSDU Size = ave (Nominal MSDU Size1, Nominal MSDU Size2,..., Nominal MSDU Size)
It shall be represented by

Note that min () represents a function for obtaining the minimum value of elements in parentheses, and add () represents a function for obtaining the sum of elements in parentheses. ave () represents a function for obtaining an average value of elements in parentheses. Also,
Delay Bound r,
Mean Data Rater,
Nominal MSDU Size,
“allowable delay time of r-th TS (allowable by application)”,
"Average value of data rate (input to MAC) of r-th TS",
“Average value (unit: octet) of frame size (data size input to MAC) of r-th TS”.

FIG. 27 is a diagram illustrating an example in which the MSDU concatenation number y is determined using the above procedure. In FIG.
n = 4,
Delay Bound = 1 [ms], Nominal MSDU Size = 2000 [octet],
It is assumed that Mean Data Rate = 48M [bit / sec]. Also, it is assumed that PSDU # 1, PSDU # 7, and PSDU # 8 are erroneous once each. Applying these parameters to the procedure shown in FIG.
x = Delay Bound / n = 0.25 [ms],
y = Mean Data Rate * x / (Nominal MSDU Size * 8) = 3 [pieces] (when there is no retransmission),
y = 0 (in case of resending),
And
As shown in FIG. 22, every 0.25 ms, when there is no retransmission data, a wireless packet in which three MSDUs are concatenated is transmitted, and when there is retransmission data, retransmission MSDUs are concatenated and transmitted.

(Seventh embodiment)
In the seventh embodiment, a method for determining the number of connections y when connecting a plurality of MSDUs will be described. In particular, in the seventh embodiment, y is obtained from the QoS parameters when retransmission is considered and the number of times of retransmission of data stored in the queue.

  FIG. 28 is a flowchart illustrating a procedure in which the controller 16 in the MAC unit described with reference to FIG. 2 in the first embodiment determines the MSDU concatenation number y based on the QoS parameters. First, ni (1 or more real number) is determined according to mi for each queue (step K1). Next, xi = Delay Bound / ni [ms] is derived for each queue (step K2), and yi for each queue is derived (step K3). Next, yi for each queue is notified to the buffer 11 (step K4), and changes in the QoS parameters and mi are detected (step K5). In step K5, if there is a change in the QoS parameters and mi, the process proceeds to step K1, and if there is no change, the determination in step K5 is repeated. Here, ni, yi, and mi indicate the values of n, y (the number of connected MSDUs) and m (the maximum number of retransmissions among the retransmission data stored in the queue) in the i-th queue. .

In addition, as an example of the method of determining ni according to mi in the above step K1,
When mi> 0, ni = 4 * mi,
When mi = 0, ni = 4,
Thus, a method of increasing monotonously according to mi can be considered.
As an example of deriving yi in step K3,
yi = roundup (Mean Data Rate * xi / (Nominal MSDU Size * 8)),
Can be considered. In the above formula, the function roundup () indicates a process of rounding up the number in parentheses to an integer.

However, in the case described in the third embodiment in which a plurality of communication partner STAs and ACs have the same TS, the above-described Delay Bound,
Mean Data Rate,
Nominal MSDU Size,
Delay Bound = min (Delay Bound 1, Delay Bound 2,..., Delay Bound n),
Mean Data Rate = add (Mean Data Rate 1, Mean Data Rate 2,..., Mean Data Rate n),
Nominal MSDU Size = ave (Nominal MSDU Size1, Nominal MSDU Size2,..., Nominal MSDU Size)
It shall be represented by

Note that min () represents a function for obtaining the minimum value of elements in parentheses, and add () represents a function for obtaining the sum of elements in parentheses. ave () represents a function for obtaining an average value of elements in parentheses. Also,
Delay Bound r,
Mean Data Rater,
Nominal MSDU Size,
“allowable delay time of r-th TS (allowable by application)”,
"Average value of data rate (input to MAC) of r-th TS",
“Average value (unit: octet) of frame size (data size input to MAC) of r-th TS”.

FIG. 29 is a diagram illustrating an example in which the MSDU concatenation number y is determined using the above procedure. In FIG.
Delay Bound = 1 [ms],
Nominal MSDU Size = 2000 [octet],
It is assumed that Mean Data Rate = 48M [bit / sec]. Further, it is assumed that PSDU # 1 is erroneous three times and PSDU # 7 and PSDU # 8 are erroneous once. Applying these parameters to the procedure shown in FIG.
y = Mean Data Rate * 0.25 / (Nominal MSDU Size * 8) = 3 [pieces] (in the case of no retransmission (m = 0)),
y = 3 (when m = 1),
y = roundup (1.5) = 2 (when m = 2),
y = 1 (when m = 3),
And
As shown in FIG. 29, retransmission MSDU and new MSDU are concatenated and transmitted according to m. As can be seen from FIG. 29, when y is determined by the method shown in FIG. 28, when m is large (transmission delay is a big problem), priority is given to reducing the transmission delay and m is small (transmission delay). If this is not a big problem, it can be seen that the number of concatenated MSDUs y is increased to give priority to transmission efficiency.

Here, for reference, FIG. 30 is similar to FIG.
n = 4,
Delay Bound = 1 [ms],
Nominal MSDU Size = 2000 [octet],
Assuming that Mean Data Rate = 48M [bit / sec], and assuming that PSDU # 1 is erroneous three times and PSDU # 7 and PSDU # 8 are erroneous once each. When these parameters are applied to the procedure of FIG. 24, the operation is as shown in FIG. 30. Although the transmission efficiency is higher than when the method of the seventh embodiment (FIG. 28) is applied, an error occurs. It can be seen that the transmission delay of consecutive PSDUs (PSDU # 1) increases.

  In the fifth, sixth, and sixth embodiments, the algorithm for determining yi has been described. However, suitable conditions such as an algorithm that emphasizes improvement of transmission efficiency and an algorithm that emphasizes reduction of transmission delay are different. Therefore, it is conceivable to change the algorithm applied by AC, or to change the algorithm applied depending on PER (Packet Error Rate) and propagation path conditions.

1 is a block diagram illustrating a schematic configuration of a wireless transmitter according to a first embodiment. It is a block diagram which shows schematic structure of the MAC part which concerns on 1st Embodiment. It is a block diagram which shows schematic structure of buffer which concerns on 1st Embodiment. It is a block diagram which shows schematic structure of the queue which concerns on 1st Embodiment. 1 is a diagram illustrating a configuration of a wireless LAN system according to a first embodiment. It is a flowchart which shows operation | movement of buffer which concerns on 1st Embodiment. (A) is a figure showing the data unit before a connection in 1st Embodiment, (b) is a figure showing the data unit after a connection in 1st Embodiment. 1 is a block diagram illustrating a schematic configuration of a wireless transmitter according to a first embodiment. In 1st Embodiment, it is a figure which shows a mode that it connects after performing error correction encoding for every data unit. It is a block diagram which shows schematic structure of the FEC encoder which concerns on 1st Embodiment. In 1st Embodiment, it is a figure which shows a mode that it connects after performing error correction encoding for every data unit. In a 1st embodiment, it is a figure showing signs that error correction coding is performed after connecting data units. In a 1st embodiment, it is a figure showing signs that error correction coding is performed after connecting data units. It is a block diagram which shows schematic structure of the radio transmitter in the MIMO system which concerns on 1st Embodiment. It is a figure which shows a mode that the allocation to each antenna was performed for every OFDM symbol in the MIMO system which concerns on 1st Embodiment. It is a figure which shows the structure of the wireless LAN system which concerns on 2nd Embodiment. It is a figure which shows the mode of a connection of a data unit in 2nd Embodiment. It is a figure which shows the structure of the wireless LAN system which concerns on 3rd Embodiment. It is a figure which shows the mode of a connection of a data unit in 3rd Embodiment. In a 4th embodiment, it is a figure showing TSPEC (Traffic Specification element) defined by IEEE802.11e. 14 is a flowchart illustrating a procedure in which a controller in a MAC unit according to a fourth embodiment determines the number of connected MSDUs “y” based on QoS parameters. In 4th Embodiment, it is a figure which shows the mode of communication of AP and STA, and the mode of connection of a data unit. In 4th Embodiment, it is a figure which shows the mode of communication of AP and STA, and the mode of connection of a data unit. It is a flowchart which shows the procedure in which the controller in the MAC part which concerns on 5th Embodiment determines the connection number y of MSDU based on a QoS parameter. In 5th Embodiment, it is a figure which shows the mode of communication of AP and STA, and the mode of connection of a data unit. It is a flowchart which shows the procedure in which the controller in the MAC part which concerns on 6th Embodiment determines the connection number y of MSDU based on a QoS parameter. In 6th Embodiment, it is a figure which shows the mode of communication of AP and STA, and the mode of connection of a data unit. It is a flowchart which shows the procedure in which the controller in the MAC part which concerns on 7th Embodiment determines the connection number y of MSDU based on a QoS parameter. In 7th Embodiment, it is a figure which shows the mode of communication of AP and STA, and the mode of connection of a data unit. It is a figure which shows the mode of communication of AP and STA at the time of applying the algorithm which concerns on 5th Embodiment, and the mode of connection of a data unit. It is a figure which shows the structure of the wireless packet in the conventional wireless LAN system. It is a figure which shows the example which compared the ratio of the preamble when not connecting with the case where a data unit is connected in the wireless packet in the conventional wireless LAN system. It is a figure which shows the mode of the connection of the data unit in the conventional wireless LAN system. It is a block diagram which shows schematic structure of the MAC part in the conventional radio transmitter. It is a block diagram which shows schematic structure of buffer in the MAC part of the conventional radio transmitter. It is a flowchart which shows the operation | movement of buffer in the MAC part of the conventional radio transmitter. It is a figure which shows the problem at the time of connecting a data unit in the conventional wireless LAN system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless transmitter 10 MAC part 20 PHY part 30 Wireless transmission part (RF)
40 Transmitting antenna 11 buffer
11-1 Memory 11-2 Determination Unit 11-3 Output Control Unit 11-4 Control Unit 11a Mapping to AC / STA
11b-11e Queue 11f-11i CSMA / CA
11k Internal Collision Resolution
12 scheduler
13 Encryption unit 14 MAC Header addition unit 15 FCS addition unit 16 (MAC) controller
21 FECencoder
21a Termination processing unit 21b Error correction coding unit 22 modulator
23 IFFT
24 filter
25 (PHY) controller
40 AP
41 STA1
42 STA2
120 S / P converter

Claims (21)

Determining whether the number of data units stored in a plurality of queues assigned to correspond to the wireless communication device of the communication partner and the QoS class has exceeded a threshold defined as the number of data units included in one wireless packet The wireless transmission method of outputting the stored data unit when the data unit stored in any one of the queues exceeds the threshold. Based on the data unit length information indicating a length of each data unit that has been input, performs error correction coding for each of the data units, and wherein the linking each data unit after the error correction coding according Item 2. The wireless transmission method according to Item 1 . The wireless transmission method according to claim 1 , wherein the threshold is determined based on a QoS parameter determined for each application having a different QoS class.   Data included in one wireless packet based on QoS parameters determined for each application having a different QoS class, and the number of retransmissions of a waiting retransmission data unit for each wireless communication device of a communication partner and another application having a different QoS class A wireless transmission method characterized by determining a threshold value determined as the number of units.   Based on a QoS parameter determined for each application having a different QoS class, a threshold value determined as the number of data units included in one wireless packet is determined, and the application having a different QoS class and the wireless communication partner are used as the threshold value. 5. The wireless transmission method according to claim 4, wherein a numerical value obtained by adding the number of waiting retransmission data units for each communication device is the number of data units included in one wireless packet.   Based on the QoS parameters determined for each application having different QoS classes, a threshold value determined as the number of data units included in one wireless packet is determined, and for each application having a different QoS class and each wireless communication device of the communication partner When the maximum number of retransmissions of the waiting retransmission data unit is 0, the number of data units included in one wireless packet is set as the determined threshold value, while the application having a different QoS class and the wireless communication partner 5. The wireless transmission method according to claim 4, wherein the threshold is set to 0 when the maximum number of retransmissions of waiting retransmission data units for each communication device is not 0.   5. The radio transmission method according to claim 4, wherein the threshold is decreased as the maximum number of retransmissions of the data unit is increased, and the threshold is increased as the maximum number of retransmissions of the data unit is decreased.   The QoS parameter is an allowable delay time, an average data rate of data input to the MAC unit, and an average value of the data size input to the MAC unit, and is acceptable for an application. The wireless transmission method according to any one of claims 3 to 7. A MAC unit that performs transmission control, a PHY unit that performs electrical conversion and mechanical work for sending data output from the MAC unit to a communication line, and data output from the PHY unit as a radio signal A wireless transmitter that performs wireless transmission using a wireless packet that includes a plurality of data units.
A plurality of queues assigned corresponding to the wireless communication device and QoS class of the communication partner;
A determination unit that determines whether or not the number of data units accumulated in each queue exceeds a threshold defined as the number of data units included in one wireless packet;
An output control unit that controls to output the data units stored in the queue when the number of data units stored in any of the queues exceeds the threshold as a result of the determination. A wireless transmitter.   10. The wireless transmission according to claim 9, further comprising: a termination processing unit that performs termination processing at the time of an error correction code for each data unit based on data unit length information indicating a length of each input data unit. Machine.   The wireless transmission according to claim 9, further comprising a MAC control unit that determines a threshold value determined as the number of data units included in one wireless packet based on a QoS parameter determined for each application having a different QoS class. Machine.
A MAC unit that performs transmission control, a PHY unit that performs electrical conversion and mechanical work for sending data output from the MAC unit to a communication line, and data output from the PHY unit as a radio signal A wireless transmitter that performs wireless transmission using a wireless packet that includes a plurality of data units.
Data included in one wireless packet based on QoS parameters determined for each application having a different QoS class, and the number of retransmissions of a waiting retransmission data unit for each wireless communication device of a communication partner and another application having a different QoS class A wireless transmitter comprising a MAC control unit for determining a threshold value determined as the number of units. The MAC control unit
Based on a QoS parameter determined for each application having a different QoS class, a threshold value determined as the number of data units included in one wireless packet is determined, and the application having a different QoS class and the wireless communication partner are used as the threshold value. 13. The wireless transmitter according to claim 12, wherein a numerical value obtained by adding the number of waiting retransmission data units for each communication device is the number of data units included in one wireless packet. The MAC control unit
Based on the QoS parameters determined for each application having different QoS classes, a threshold value determined as the number of data units included in one wireless packet is determined, and for each application having a different QoS class and each wireless communication device of the communication partner When the maximum number of retransmissions of waiting retransmission data units is 0, the number of data units included in one wireless packet is set as the determined threshold value,
13. The wireless communication according to claim 12, wherein the threshold is set to 0 when the maximum number of retransmissions of waiting retransmission data units for each application and communication partner wireless communication device with different QoS classes is not 0. Transmitter. The MAC control unit
13. The radio transmitter according to claim 12, wherein the threshold is decreased as the maximum number of retransmissions of the data unit is increased, and the threshold is increased as the maximum number of retransmissions of the data unit is decreased.   The QoS parameter is an allowable delay time, an average data rate of data input to the MAC unit, and an average value of the data size input to the MAC unit, and is acceptable for an application. The wireless transmitter according to any one of claims 12 to 15.   An access point comprising the wireless transmitter according to any one of claims 9 to 16.   A station comprising the wireless transmitter according to claim 9.   A wireless LAN system comprising the access point according to claim 17 and the station according to claim 18.   An image transmission apparatus comprising the wireless transmitter according to claim 9. A tuner comprising the wireless transmitter according to any one of claims 9 to 16.

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