WO2005119969A1 - 無線伝送方法 - Google Patents
無線伝送方法 Download PDFInfo
- Publication number
- WO2005119969A1 WO2005119969A1 PCT/JP2005/010055 JP2005010055W WO2005119969A1 WO 2005119969 A1 WO2005119969 A1 WO 2005119969A1 JP 2005010055 W JP2005010055 W JP 2005010055W WO 2005119969 A1 WO2005119969 A1 WO 2005119969A1
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- WIPO (PCT)
- Prior art keywords
- transmission
- packet
- data
- multicast
- retransmission
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
- H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
- H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
- H04L1/1867—Arrangements specially adapted for the transmitter end
- H04L1/1887—Scheduling and prioritising arrangements
Definitions
- the present invention relates to a wireless transmission method that improves the reliability of transmission by retransmission processing, particularly when video or audio data is transmitted by multicast or broadcast using wireless technology.
- FIG. 55 shows a transmission time chart of the conventional wireless transmission device described in Patent Document 1.
- the vertical axis in the left column indicates the terminal type, and the horizontal axis indicates the time axis.
- 600, 6001, 602, 603, 604, and 605 are multicast packets simultaneously transmitted from the transmitting terminal to the first receiving terminal, the second receiving terminal, and the third receiving terminal.
- 606 and 607 are unicast packets individually transmitted from the transmitting terminal to the first receiving terminal and the second receiving terminal, respectively.
- 707 is a broadcast packet which retransmits the broadcast packet 607.
- 60 61 is an Ack packet for confirming the reception success of the broadcast packet 606.
- Reference numeral 6072 denotes a Nack packet which is a confirmation of reception failure of the multicast packet 607.
- Reference numeral 7071 denotes an Ack packet which is a confirmation of successful reception of the retransmitted cast packet 707.
- a multicast packet is simultaneously transmitted to a first receiving terminal, a second receiving terminal, and a third receiving terminal by wireless multicast transmission.
- the wireless packet transmission of the multicast packet 606 to the transmitting terminal and the transmitting packet of the multicast packet 607 to the second receiving terminal are individually performed.
- a receiving terminal sends a MAC layer packet to a transmitting terminal. Do not return Ack packet which is success confirmation packet (or Nack packet which is reception failure confirmation packet). For this reason, in multicast transmission, it is difficult to ensure the reliability of transmission, because retransmission control using Ack packets (or Nack packets) cannot be performed. Since the transmission quality of wired transmission is superior to that of wireless transmission, there may be no practical problems without retransmission control using Ack packets (or Nack packets). Often impractical due to low cost.
- the first receiving terminal in the first transmission of the multicast packet 600, the first receiving terminal has failed in reception, but is correctly received in the second transmission 601. A similar situation occurs for the second receiving terminal, the third receiving terminal, and the broadcast packets 602, 603, 604, 605.
- the probability of causing a reception error in one transmission is Pe
- the reception probability is improved by transmitting the retransmission packet 707 of the second broadcast packet even if the packet reception fails.
- the retransmission is determined by whether the transmitting terminal received Nack packet 6072 or not. Is determined based on whether an Ack packet has not been received.
- the transmitting terminal receives the Ack packet 7071, the retransmission control ends.
- Patent Document 1 JP-A-10-173668 (pages 1-8, FIG. 6)
- a multicast packet or a broadcast packet is transmitted a plurality of times at first, so that the probability of receiving all the multicast packets or the broadcast packets must be increased repeatedly.
- a huge transmission band was required in proportion to the number of times.
- other packet transmission / reception bands that must secure a band that is at least twice the required number of times of transmission band must be secured, the problem becomes I have.
- An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a wireless transmission method that improves band use efficiency and improves reception probability in wireless multicast or broadcast.
- a first invention is a wireless transmission method for performing Mac layer multicast or broadcast transmission between a transmitting terminal and a receiving terminal
- the reliability of wireless multicast or broadcast transmission which has been low in quality in the past, is improved during band-secured or priority-controlled wireless transmission by improving the band use efficiency. It can be realized as it is.
- the step of retransmitting data higher than the Mac layer includes the above-mentioned bandwidth securing type or high priority, multicast or broadcast bucket, or a second or lower priority. It is desirable to control transmission of retransmission data.
- the step of retransmitting data higher than the Mac layer is a first sub-step for transmitting retransmission data using a multicast packet, or
- the method further comprises a second sub-step for transmitting retransmission data to a plurality of receiving terminals by using a multicast or broadcast packet.
- At least a part of a plurality of data groups higher than the Mac layer may be combined, and the combined data may be transmitted using the broadcast packet.
- the step of requesting the retransmission of the detected missing data group on the receiving terminal side may be the same as the bandwidth securing type or high priority, the same as the multicast or broadcast packet, or the second or lower priority. It is desirable to control the transmission of the retransmission request packet every time.
- the step of requesting retransmission of the detected missing data group includes the first sub-step of transmitting retransmission request data using a multicast packet, or using a multicast or broadcast packet. It is preferable to include a second sub-step for transmitting the retransmission request data.
- the step of retransmitting data higher than the Mac layer includes: It is desirable to limit the time for the retransmission.
- the step of retransmitting data higher than the Mac layer includes retransmitting request data including a plurality of sequence numbers of the detected missing data group using one broadcast packet. Can be sent.
- the multicast transmission scheme of the present invention is applied to a network communication system in which stream data such as video and audio and asynchronous data such as Internet data are mixed and transmitted between a transmitting terminal and a plurality of receiving terminals.
- stream data such as video and audio
- asynchronous data such as Internet data
- a stream transmission period for transmitting the stream while securing a necessary transmission band and an asynchronous transmission period for transmitting the asynchronous data are provided.
- the transmitting terminal multicast distributes the stream data to multiple receiving terminals during the stream transmission period.
- the receiving terminal makes an error determination on the received stream data, and if the stream data cannot be received correctly, the asynchronous
- the transmitting terminal transmits a request for retransmission of the stream data to the transmitting terminal during the transmission period, and upon receiving the retransmission request from the receiving terminal, the transmitting terminal multicast retransmits the stream data during the stream transmission period of the next communication cycle.
- the transmitting terminal and all the receiving terminals wait for a time given by a product of a randomly selected natural number and a predetermined time.
- the force can also be configured to transmit asynchronous data.
- the natural number randomly selected before transmitting the retransmission request is smaller than the natural number randomly selected before transmitting other asynchronous data.
- the multicast communication method according to the present invention is a multicast communication method used in a transmitting terminal that multicast-distributes stream data to a plurality of receiving terminals,
- a retransmission step of retransmitting the stream data that has failed to be distributed based on the transmission confirmation result wherein the transmitting terminal transmits the stream data within the fixed period before the transmission confirmation step.
- the retransmission step includes a multicast retransmission step of performing, by multicast, retransmission of the stream data whose distribution has failed, wherein the multicast retransmission step is performed before the multicast transmission step within the fixed period. It is desirable to be executed in
- the retransmitting step includes a multicast retransmitting step of performing retransmission of the stream data that has failed to be distributed by a unicast, wherein the multicast retransmitting step includes the multicast transmitting step and the transmission confirmation within the fixed period. It is desirable to execute it after the step.
- the retransmission step includes a multicast retransmission step of performing retransmission of the stream data that has failed to be distributed by using a multicast, and a multicast retransmission step of performing retransmission of the stream data that has failed to deliver by using a multicast.
- the multicast retransmission step is performed first in the fixed period, the multicast transmission step is performed second, the transmission confirmation step is performed third, and the multicast retransmission is performed.
- the step is executed fourthly, and it is preferable that the broadcast retransmission step ends the process after the fixed period has elapsed and shifts to the next process of the fixed period.
- the multicast retransmission step may include retransmitting the multicast packet preferentially when the slave station communication device has failed in reception, and completing all retransmissions of the stream data for which distribution has failed.
- the remaining time of a certain period becomes equal to or less than the threshold value, retransmission is terminated, and in the unicast retransmission step, the number of the slave station communication devices that failed to receive is small! It is preferable that the retransmission of the stream data is completed, or that the retransmission is completed when the predetermined period ends.
- the transmission confirmation step the power of individually inquiring by a multicast whether or not the power has been successfully distributed to each of the plurality of slave station communication devices or the collective transmission to the plurality of slave station communication devices is successful. This is a process to check whether the The
- the retransmission step includes a multicast retransmission step of performing retransmission of the stream data that has failed in distribution by multicast, wherein the multicast retransmission step and the multicast transmission step are performed within the predetermined period. It is preferable that the transmission confirmation step is executed before the transmission confirmation step, and the transmission confirmation step is started when the remaining time of the certain period becomes equal to or less than a threshold value.
- FIG. 1 is a time chart of a wireless transmission apparatus according to Embodiments 1 to 3 of the present invention.
- FIG. 2 is a system diagram of a wireless transmission device according to Embodiments 1 to 4 of the present invention.
- FIG. 3 is a time chart of the wireless transmission device according to the first embodiment of the present invention.
- FIG. 4 is a block diagram of a wireless transmission terminal according to Embodiments 1 to 5 of the present invention.
- FIG. 5 is a block diagram of a wired transmission unit according to the first to fifth embodiments of the present invention.
- FIG. 6 is a configuration diagram of a wired Ethernet packet according to the first to fourth embodiments of the present invention.
- FIG. 7 is a state diagram of a memory according to the first to fourth embodiments of the present invention.
- FIG. 8 is a block diagram of wireless transmission means according to Embodiments 1 to 5 of the present invention.
- FIG. 9 is a block diagram of buffer means according to the first to fifth embodiments of the present invention.
- FIG. 10 is a configuration diagram of a wireless multicast data packet according to Embodiments 1 to 5 of the present invention.
- FIG. 11 is a block diagram of a wireless reception terminal according to Embodiments 1 to 5 of the present invention.
- FIG. 12 is a state diagram of a memory according to the first to fifth embodiments of the present invention.
- FIG. 13 is a configuration diagram of a retransmission request packet according to Embodiments 1 to 5 of the present invention.
- FIG. 14 is a configuration diagram of a retransmission packet according to Embodiments 1 to 5 of the present invention.
- FIG. 15 is a time chart of the wireless transmission device according to the first embodiment of the present invention.
- FIG. 16 is a time chart of the wireless transmission device according to the first embodiment of the present invention.
- FIG. 17 is a time chart of the wireless transmission device according to the first embodiment of the present invention.
- FIG. 18 is a time chart of the wireless transmission device according to the first embodiment of the present invention.
- FIG. 19 is a diagram showing a configuration of a receiving terminal according to Embodiment 2 of the present invention.
- FIG. 20 is a diagram showing a configuration of transmission timing adjusting means in the receiving terminal. [21] Schematic diagram for explaining asynchronous data transmission timing during the asynchronous transmission period
- FIG. 22 is a time chart illustrating an example of a packet sequence of the wireless transmission device according to the third embodiment of the present invention.
- FIG. 25 Time chart of a wireless transmission device
- FIG. 28 Time chart of a wireless transmission device
- FIG. 32 A diagram showing a configuration of a wireless network to which the method of FIG. 31 is applied.
- FIG. 34 A diagram showing a device configuration of a wireless slave station.
- FIG. 35 A diagram showing a detailed configuration of an asynchronous data transmission buffer 340 of a wireless slave station.
- FIG. 37 is a time chart showing a packet sequence example of the wireless transmission device in the sixth embodiment.
- FIG. 39 A diagram showing a configuration of a transmission buffer in Embodiment 6.
- FIG. 40 is a configuration diagram of a multicast communication system according to Embodiment 7.
- FIG. 42 A diagram showing a frame configuration of a radio signal 1416.
- FIG. 44 A diagram showing the configuration of a radio unit 14155
- FIG. 47 is a diagram showing a configuration of a master station communication device according to an eighth embodiment.
- FIG. 48 A diagram showing a system configuration assumed in a ninth embodiment.
- FIG. 49 A diagram showing the configuration of the buffer of the second transmitting terminal
- FIG. 50 A flowchart for explaining the operation performed by the buffer 14152
- FIG. 51 is a flowchart illustrating an operation performed by a transmission confirmation processing unit 14156
- FIG. 52 is a flowchart illustrating the operation performed by a broadcast retransmission processing unit 14157
- FIG. 53 is a flowchart for explaining the operation performed by a multicast retransmission processing unit 14158
- FIG. 54 is a flowchart for explaining the operation performed by the multicast distribution processing unit 14159
- FIG. 55 A transmission time chart of a conventional wireless transmission device
- FIG. 1 is a time chart illustrating a basic packet sequence of the wireless transmission device according to the first embodiment of the present invention.
- reference numerals 100, 101, and 102 denote first to N-th multicast packets transmitted simultaneously from a transmitting terminal to a first receiving terminal, a second receiving terminal, and a third receiving terminal.
- 103 and 104 are a retransmission packet of the second packet and a retransmission packet of the Nth packet, respectively.
- 105 is another packet.
- 300 and 301 are retransmission request packets for performing a retransmission request when the receiving terminal fails to receive the multicast packet.
- the time chart is divided into time slots, and the first band securing period-> the first non-band securing period-> the second band securing period
- the outer period is repeated alternately.
- the bandwidth securing period the first multicast bucket 100, the second multicast packet 101,..., And the Nth multicast packet are transmitted from the transmitting terminal to the receiving terminal.
- the bandwidth used is allocated to the transmitting terminal in advance, so that the available bandwidth does not decrease due to interruption of other terminals. That is, this period is a period reserved for transmission of the first to N-th multicast packets without packets other than the first to N-th multicast packets being transmitted to other terminals.
- the non-bandwidth reservation period is a period in which each terminal participating in the network may freely transmit packets, contrary to the above-mentioned band reservation period. Therefore, when a certain terminal tries to send a packet, it cannot perform packet transmission because another terminal is transmitting, or a packet to be sent by another terminal collides with a packet to be sent by itself. Transmission may not be possible.
- the band securing period is suitable for a case where data must always be transmitted at a constant rate, for example, transmitting video and audio in real time with the highest priority. There is no need to send data in the, haze, transmission priority is low !, suitable for data transmission!
- the video and audio data are transmitted and the non-band reservation period is used for transmission of retransmission data and other data, and packets that fail to be received during the band reservation period are retransmitted during the non-band reservation period.
- FIG. 2 is a system diagram according to Embodiment 1 of the present invention.
- 1 is an AV server
- 2 is a wired Ethernet HUB
- 3 is a first wireless transmitting terminal
- 4 is a second wireless transmitting terminal
- 5 is a wired Ethernet connecting 1, 2, 3, and 4.
- 6 is the first wireless receiving terminal
- 7 is the second wireless receiving terminal
- 8 is the third wireless receiving terminal
- 9 is the fourth wireless receiving terminal
- 10 is the fifth wireless receiving terminal
- 11 is the sixth wireless receiving terminal. It is a wireless receiving terminal.
- the first wireless transmission terminal 3, the first wireless reception terminal 6, the second wireless reception terminal 7, and the third wireless reception terminal 7 are a parent and child that perform wireless communication using the IEEE802.il wireless LAN technology.
- the first wireless transmitting terminal 3 is an AP (access point: master unit)
- the first, second, and third wireless receiving terminals 6, 7, and 8 are STAs (stations: slave units).
- the first, second, and third wireless receiving terminals 6, 7, and 8 constitute a first multicast group 12 that receives the same multicast packet.
- the second wireless transmitting terminal 4 and the fourth wireless receiving terminal 9, the fifth wireless receiving terminal 10, and the sixth wireless receiving terminal 11 perform wireless communication using the IEEE 802.11 wireless LAN technology.
- the second wireless transmitting terminal 4 is an AP (access point: master unit)
- the fourth, fifth, and sixth wireless receiving terminals 9, 10, and 11 are STAs (stations: slave units).
- the fourth, fifth, and sixth wireless receiving terminals 9, 10, and 11 form a second multicast group 13 that receives the same multicast packet.
- Video and audio data packets are input from the AV server 1 via the wired Ethernet 5 to the wired Ethernet HUB2.
- the wired Ethernet HUB 2 repeats the input packet and distributes it to the first wireless transmission terminal 3 and the second wireless transmission terminal 4.
- the wired Ethernet HUB 2 performs either an operation of repeating all input packets to all outputs or a switching operation of repeating only specific packets to a specific terminal. For example, when performing a switching operation, a packet transmitted only to the first multicast group 12 is repeated only to the first wireless transmission terminal 3, and a packet transmitted only to the second multicast group 13 is transmitted to the second multicast group 13. An operation to repeat only to the wireless transmission terminal 4 is performed.
- the first wireless transmission terminal 3 and the second wireless transmission terminal 4 each receive video and audio data to be delivered to the wireless reception terminal under their control from the wired Ethernet HUB2, and receive the wireless communication under their own control. Multicast distribution to receiving terminals.
- all the terminals (the first wireless receiving terminal 6, the second wireless receiving terminal 7, and the third wireless receiving terminal 8) managed by the first wireless transmitting terminal 3 are the first multi-carriers. Since it belongs to the multicast group 12, the first wireless transmission terminal 12 receives the video / audio data packet addressed to the first multicast group and distributes it to the first multicast group. All terminals managed by the second wireless transmitting terminal 4 (the fourth wireless receiving terminal 9, the fifth wireless receiving terminal 10, and the sixth wireless receiving terminal 11) are connected to the second multicast group. Therefore, the second wireless transmission terminal 4 receives the video / audio data packet addressed to the second multicast group 13 and distributes it to the second multicast group 13.
- FIG. 3 is a time chart illustrating a packet sequence example of the wireless transmission device according to the first embodiment of the present invention. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.
- reference numeral 3001 denotes an Ack packet transmitting a reception success confirmation of the first retransmission request packet 300
- reference numeral 1031 denotes an Ack packet transmitting a reception success confirmation of the retransmission packet 103 of the second packet
- reference numeral 1041 denotes an ack packet.
- This is an Ac ack packet that transmits a confirmation of successful reception of the retransmission packet 104 of the N packet.
- the transmission terminal corresponds to the first wireless transmission terminal 3 in FIG.
- the transmitting terminal has the first wireless transmitting terminal 3 and the second wireless transmitting terminal 4 and the 1S both perform the same operation.Therefore, there is no difference in the description regardless of which one is used.
- the first receiving terminal in FIG. 3 is the first wireless receiving terminal 6 in FIG. 2
- the second receiving terminal in FIG. 3 is the second wireless receiving terminal 7 in FIG.
- the third receiving terminal corresponds to the third wireless receiving terminal 8 in FIG.
- FIG. 4 shows the configuration of the transmitting terminal that transmits the first multicast packet 100, the second multicast packet 101, and the N-th multicast packet 102 during the first bandwidth reservation period.
- 14 is an input / output terminal for inputting / outputting a packet from the wired Ethernet 5
- 15 is a wired transmission means for performing packet transmission / reception on the wired Ethernet 5
- 16 is a transmission terminal.
- CPU for controlling internal means
- 17 for memory means for storing data higher than the Mac layer
- 18 for wireless transmission means for transmitting and receiving packets wirelessly
- 19 for the internal bus connecting CPU 16 and other means
- Reference numeral 20 denotes first timer means for measuring an operation time
- reference numeral 21 denotes an antenna for transmitting and receiving wireless packets.
- a wired Ethernet packet received from the wired Ethernet 5 via the input / output terminal 14 is first input to the wired transmission unit 15.
- the wired transmission means 15 is compliant with IEEE802.3, that is, the wired Ethernet standard, and performs an operation of receiving a packet from the wired Ethernet 5 using the Ethernet MAC protocol and outputting the packet to the internal bus 19.
- FIG. 5 is a block diagram illustrating an internal configuration of the wired transmission unit 15.
- Reference numeral 22 denotes an input / output terminal for inputting and outputting packets conforming to the wired Ethernet IEEE802.3.
- 23 is a wired physical layer signal processing means for modulating and demodulating packets transmitted on the wired Ethernet 5.
- Reference numeral 24 denotes a MAC layer protocol processing means for processing the MAC protocol of the wired Ethernet 5.
- Reference numeral 25 denotes buffer means for temporarily storing data to be input / output via the internal bus 19.
- 26 is an input / output terminal for connecting to the internal bus 19.
- the packet input from the input terminal 22 is input to the wired physical layer signal processing means 23 to demodulate the wired Ethernet modulation into a MAC packet.
- the demodulated MAC packet is then input to the MAC layer protocol processing means 24.
- Fig. 6 shows the configuration of an input MAC packet, which consists of a MAC header, IP header, UDP header, transmission data, and FCS (frame checksum) from the top.
- the head is a data link layer header, which is a MAC header.
- the MAC header is composed of the source MAC address, destination MAC address, upper protocol type, etc., and indicates the source address at the MAC layer, the destination address at the MAC layer, and the type of higher protocol. I have.
- IP Internet Protocol
- the network layer which includes the source IP address, destination IP address, and upper protocol type.
- This network layer is the layer that routes packets.
- An IP address that is a dedicated address different from the MAC address is used.
- IP header there is a higher protocol type that indicates a protocol type of a higher transport layer.
- the upper protocol is often UDP.
- the UDP header is composed of a source port number and a destination port number as shown, and plays a role in determining a virtual input / output destination of data inside the terminal.
- the upper part of UDP contains the actual transmission data, and finally has a checksum (FCS) to check for transmission errors in wired packets.
- FCS checksum
- Such a packet is output from the wired physical layer signal processing means 23 and input to the MAC layer protocol processing means 24.
- the MAC layer protocol processing means 24 performs the protocol processing of transmitting and receiving the MAC packet in FIG. 6 and the processing of judging whether or not the packet is addressed to the own terminal based on the previous destination MAC address and receiving the packet at the own terminal. .
- the MAC header is removed to generate an upper data packet, which is input to the next buffer means 25.
- the buffer means 25 serves to temporarily store the upper data packet input from the MAC layer protocol processing means 24 when the data packet is transmitted to the internal bus 19 via the input / output terminal 26.
- the stored upper data packet is transferred to the CPU 16 when the CPU 16 is ready to receive the data packet and when the internal bus 19 becomes available.
- the CPU 16 When receiving the upper data packet, the CPU 16 first performs a UDP / IP process. That is, the IP address and UDP port are checked, and it is determined whether or not the own terminal has the data capability to be multicast to the radio. If the terminal itself is data to be multicast to the wireless, the terminal performs a write operation to the memory means 17.
- FIG. 7 is a memory state diagram showing the storage state of data in the memory means 17.
- the CPU 16 adds a sequence number indicating the order of the data at the beginning.
- data is held in units of N (N is an integer of 1 or more) as many as transmission units in a band securing period in the next wireless section.
- N is an integer of 1 or more
- the N data groups shown in FIG. This is a unit of data that is multicast-transmitted in the first bandwidth reservation period and only data for which a reception error has occurred is retransmitted in the first non-bandwidth reservation period.
- the CPU 16 stores the next (N + 1) th data in the memory means 17 with the sequence number added to the beginning of the N * 2N data. I do. Actually, the CPU 16 stores at least two or more sets of N packet groups in the memory means 17 and after the wireless transmission during the bandwidth securing time and the retransmission control outside the bandwidth securing are completed. Then, data that no longer needs to be retransmitted is deleted from the memory means 17.
- the CPU 16 delivers the first to N-th data transmitted in the first band securing period to the wireless transmission unit 18 via the internal bus 19.
- the CPU 16 performs appropriate UDP / IP processing as necessary, and the sequence number is transmitted in the payload of the UDP / IP packet.
- the CPU 16 newly adds, at the beginning of the UDP / IP payload portion, an identifier indicating the type of data transmitted in the payload portion.
- FIG. 8 is a block diagram showing the internal configuration of the wireless transmission means 18.
- the buffer unit 29 is configured to transmit the N sequence numbers stored in the memory unit 17 + data packets higher than the MAC layer in which the UDP / IP packets are transmitted, when the wireless transmission timing arrives.
- a wireless transmission buffer or the like is provided to enable wireless transmission, and is composed of a plurality of buffers having a storage capacity at least equal to or greater than the packet length of a wireless section.
- FIG. 9 is a block diagram showing the configuration of the force buffer means 29 which receives wireless transmission data input from the CPU 16 from the internal node 19 via the input / output terminal 28 to the buffer means 29.
- the buffer means 29 includes an input / output terminal 33, a data transmission / reception means 34, a priority data transmission buffer means 35, a priority data output terminal 36, a normal data transmission buffer means 37, and a normal data transmission buffer means 37. It comprises a data output terminal 38, a transmission control signal input / output terminal 39, a reception buffer means 40, a reception data input terminal 41, and a reception control signal input / output terminal 42.
- the input / output terminal 33, the data transmitting / receiving means 34, the priority data transmission buffer means 35, the priority data output terminal 36, and the transmission control signal input / output terminal 39 are used.
- All or a part of the wireless transmission data of the upper data packet input from the input / output terminal 33 is distributed to the priority data transmission buffer means 35 via the data transmission / reception means 34, and the wireless transmission timing At the same time, the data is passed to the MAC processing means 30 via the priority data output terminal 36.
- the MAC processing means 30 performs management of a bandwidth securing period / non-bandwidth securing period and MAC protocol processing, reads out radio transmission data from the buffer means 29 at appropriate timing, and inputs the data to the physical layer signal processing means 32.
- the MAC processing means 30 determines whether or not the time is during the band securing period by the second timer means 31 provided therein, and switches the buffer means 29 to the transmission control signal input / output terminal during the band securing period. Data is read out from the priority data transmission buffer means 35 and transmitted using the control unit 39. The timing at which the data is transferred from the CPU 16 to the buffer means is also determined by the MAC processing means 30 being triggered by a control signal for controlling the priority data buffer means 35 and the data transmitting / receiving means 34 via the transmission control signal input / output terminal 39. You. When receiving the data request, the CPU 16 transfers the data to the wireless transmission means 18.
- the MAC processing means 30 Upon receiving the data, the MAC processing means 30 performs wireless MAC packet filtering of the data.
- the configuration of the wireless packet is shown in FIG.
- the determination of the band securing period and the transmission timing may be performed by using the first timer means 20 and inputting the same timing to the upper layer and the MAC layer.
- the configuration of the wireless packet is such that the MAC header part of the wired Ethernet packet shown earlier in Fig. 6 is replaced with the IEEE802.il wireless MAC header.
- the identifier and the sequence number described above are added to the upper data transferred by the CPU 16 to the wireless transmission unit 18.
- the wireless packet in such a form is input to the physical layer signal processing means 32, and after being modulated by the physical layer signal processing means 32 suitable for wireless transmission, is wirelessly transmitted via the antenna 21.
- the first to Nth multicast packets are transmitted to the first to third receiving terminals during the first band securing period in FIG.
- the transmitting terminal performs multicast transmission to the receiving terminal in the first band securing period, but the first to third receiving terminals have different installation environments and receiving characteristics.
- the error occurrence situation at the time differs individually.
- the first multicast packet 100 has been successfully received by all receiving terminals, but the second multicast packet 101 has failed to be received only by the first receiving terminal. Similarly, only the third receiving terminal has failed to receive the Nth multicast packet 102.
- the transmitting terminal determines whether or not the receiving terminal has successfully received the multicast packet. I can't know. This is because, if a plurality of receiving terminals unconditionally return the Ack packets, the wireless band is wasted due to the collision of the Ack packets in the wireless section, and the confirmation processing load on the transmitting side is increased.
- a receiving terminal that has failed to receive a multicast packet performs an operation of transmitting a retransmission request packet to a transmitting terminal using the first non-bandwidth reservation period.
- the first receiving terminal that has failed in the transmission transmits the first retransmission request packet 300 to the transmitting terminal using the first non-bandwidth reservation period.
- the transmitting terminal Upon normal reception of the first retransmission request packet 300, the transmitting terminal returns an Ack packet 3001 that confirms successful reception, and then refers to the contents of the retransmission request packet 300 to check the retransmission packet 103 of the second packet. It is transmitted to the first receiving terminal using a cast. Upon confirming the normal reception of the retransmitted packet 103 of the second packet, the first receiving terminal returns Ackl031 to the transmitting terminal. This operation will be described below in detail with reference to the drawings.
- FIG. 11 is a block diagram illustrating the internal configuration of the receiving terminal.
- 16 is a CPU
- 17 is a memory means
- 18 is a wireless transmission means
- 19 is an internal bus
- 20 is a first timer means.
- 43 is an AV processing means, which changes the video and audio data received via radio into a signal capable of being displayed.
- 44 is a display means for displaying the output of the AV processing means 43.
- the receiving terminal receives the first to N-th multicast packets 100, 101, 102 via the antenna 21.
- the first to N-th multicast packets 100, 101, and 102 are input to the wireless transmission means 18 and output to the internal bus 19 after the processing reverse to the transmission.
- the wireless transmission means 18 has the same configuration as the transmission means inside the transmission terminal, and is configured as shown in FIG. Since the configuration of FIG. 8 has been described on the transmitting terminal side, the description is omitted this time. In the wireless transmission means 18, first, the modulation applied at the time of transmission by the physical layer signal processing means 32 is demodulated, and the MAC packet in FIG. 10 is restored.
- the restored MAC packet is input to the MAC processing means 30, and when the multicast address indicated in the MAC header is addressed to the broadcast group to which the own station belongs, the MAC header is removed and output to the buffer means 29. Is done.
- the configuration of the buffer means 29 is the same as that described on the transmitting side as shown in FIG. During transmission, the transmission buffer system was operated, but during reception, the reception buffer system was operated. From the 41 received data input terminals, the MAC processed packet The data is input and stored in the reception buffer means 40. At this time, the MAC processing means 30 controls the writing of the received data to the receiving buffer 40 via the control signal input / output terminal 42.
- the data stored in the reception buffer means 40 is output to the internal bus 19 via the data transmission / reception means 34, the input / output terminals 33 and 28, and passed to the CPU 16.
- the data transmission / reception means 34 performs an operation of reading data from the reception buffer means 40 when the internal node 19 is usable and the CPU 16 can receive data.
- the CPU 16 that has received the data writes the received data into the memory means 17
- the CPU 16 simultaneously determines whether or not the packet should be subjected to the subsequent processing based on the IP header, the UDP header, and the identifier in FIG. That is, the IP address and UDP header are used to determine the internal destination, and the identifier is used to determine whether the data is multicast data to be stored in memory.
- FIG. 12 shows a data storage state in the memory 17.
- the power of storing the first to N-th multicast packet data is written into the memory means 17 in such a manner that it is possible to determine which sequence number of the packet data was dropped at that time.
- the positions of the first to Nth multicast packet data in the memory are fixed, and whether the packet was normally received at the beginning of the combination of the sequence number + the multicast packet data and the normal writing was performed. Is attached. That is, by referring to the inside of the memory means 17, it is possible to determine which of the first to Nth multicast packet groups transmitted during the bandwidth securing period is missing.
- FIG. 13 shows the configuration of the retransmission request packet 300.
- the CPU 16 stores an identifier indicating a retransmission request packet and a packet sequence number for performing a retransmission request in a payload portion of the Ip header and the TCP header.
- This retransmission request packet 300 is transferred to the wireless transmission means 18 via the internal bus 19.
- the retransmission request packet 300 is input to the wireless transmission means 18 via the input / output terminal 28 having the configuration shown in FIG.
- the retransmission request packet 300 input through the input / output terminal 33 has the configuration shown in FIG. It is stored in the normal data transmission buffer means 37 via the means 34 and passed to the MAC processing means 30 via the normal data output terminal 38. At this time, the MAC processing means 30 determines the first non-secured period by the built-in second timer means 31, and when the first non-secured period is reached, the MAC processing means 30 normally transmits the signal through the control signal input / output terminal 39.
- the data buffer means 37 is controlled to read the retransmission request packet 300 from the normal data buffer means 37.
- the physical layer signal processing means 32 applies modulation suitable for transmission, and the antenna 21 broadcasts the packet to the transmitting terminal via the antenna 21.
- the determination of the bandwidth securing period and the transmission timing may be made by inputting the same timing to the upper layer and the MAC layer using the first timer means 20!
- the transmitting terminal that has received the retransmission request packet 300 Upon confirming the normal reception of the wireless packet, the transmitting terminal that has received the retransmission request packet 300 returns an Ack packet 3001 to the first receiving terminal. Upon receiving the Ack packet 300 1, the first receiving terminal waits for retransmission of the packet that has made the retransmission request.
- the retransmission request packet 300 When the retransmission request packet 300 is received via the antenna 21 inside the transmitting terminal, the retransmission request packet is output to the internal bus 19 in a process reverse to the transmission.
- the wireless transmission unit 18 has the same configuration as the wireless transmission unit inside the transmitting terminal, and is configured as shown in FIG. Since the configuration of FIG. 8 has been described earlier, the description is omitted.
- the radio transmission means 18 first, the modulation applied at the time of transmission by the physical layer signal processing means 32 is demodulated, and the MAC packet in FIG. 10 is restored. The restored MAC packet is input to the MAC processing means 31, and when the address indicated in the MAC header is addressed to the own station, the MAC header is removed and output to the buffer means 29.
- the configuration of the buffer means 29 is the same as that described above as shown in FIG. The transmission buffer system was operated during transmission, but the reception buffer system was operated during reception.
- the MAC-processed packet is input and stored in the reception buffer means 40.
- the MAC processing means 30 controls the writing of the received data to the receiving buffer 40 via the control signal input / output terminal 42.
- the data stored in the receiving buffer means 40 is output to the internal bus 19 via the data transmitting / receiving means 34 and the input / output terminals 33 and 28, and passed to the CPU 16.
- the data transmission / reception means 34 can use the internal bus 19 and When the CPU 16 becomes ready to receive data, it performs an operation of reading data from the reception buffer means 40.
- the CPU 16 that has received the data writes the received data into the memory unit 17 At this time, the CPU 16 determines whether or not the packet to be processed further is based on the IP header and the TCP header in FIG. If the identifier indicates a retransmission request, the CPU 16 confirms the next packet sequence number and prepares to transmit the corresponding packet data. As shown in FIG. 7, the memory means 17 stores the data which has been multicast-transmitted earlier, and among these, retransmits the second multicast packet data requested to be retransmitted. That is, retransmission packet 103 of the second packet in FIG. 3 is transmitted to the first receiving terminal.
- FIG. 14 shows the configuration of 103 of the retransmission packet.
- the payload portion following the MAC header, IP header, and UDP header is composed of an identifier indicating the retransmission packet, a sequence number, and data. .
- This data part is the same as that of the second multicast packet that first performed multicast transmission.
- the transmission process is the same as the procedure that first performed multicast transmission in the first bandwidth reservation period, but the priority of the retransmission packet is lower than the first, so it is transmitted in the first non-bandwidth reservation period .
- the CPU 16 delivers the retransmission packet data transmitted during the first non-bandwidth-preservation period to the wireless transmission means 18 via the internal bus 19.
- the wireless transmission data input from the CPU 16 via the internal node 19 and the input / output terminal 28 is input to the buffer means 29.
- the retransmission data of the second multicast packet input from the input / output terminal 33 is distributed to the normal data transmission buffer means 37 via the data transmission / reception means 34, and the normal data is transmitted in accordance with the radio transmission timing. Is input to the MAC processing means 30 via the output terminal 38.
- the MAC processing means 30 performs management of the band securing period / non-bandwidth securing period and MAC protocol processing, reads out wireless transmission data from the buffer means 29 at appropriate timing, and inputs the data to the physical layer signal processing means 32. .
- the MAC processing means 30 determines the band securing period and transmission timing provided inside, Using the first timer means 20, the same timing may be input to the upper layer and the MAC layer to make the determination.
- the buffer means 29 is controlled using the transmission control signal input / output terminal 39, and data is read out from the normal data transmitting buffer means 37 during the non-band securing period. It will be cast.
- the timing at which the data is transferred from the CPU 16 to the buffer means is also determined by the MAC processing means 30 being triggered by a control signal for controlling the normal data buffer means 37 and the data transmission / reception means 34 via the transmission control signal input / output terminal 39. You. When receiving the data request, the CPU 16 transfers the data to the wireless transmission means 18.
- the MAC processing means 30 that has received the data converts the data into a wireless MAC packet, and the wireless packet is input to the physical layer signal processing means 32, and the physical layer signal processing means 32 modulates the data suitable for wireless transmission. , And then wirelessly transmitted via the antenna 21.
- data requested to be retransmitted using retransmission request packet 300 is transmitted to the first receiving terminal.
- the first terminal that has received the retransmitted packet 103 of the second packet retransmitted in this way returns an Ack packet 1031, which is an acknowledgment packet, to the transmitting terminal, and ends the retransmission of the packet that failed to be received. .
- the second packet retransmission packet itself may be retransmitted as shown in FIG. .
- reference numeral 1032 denotes a Nack packet transmitted when the first terminal fails to receive the retransmitted packet 103 of the second packet. This Nack packet is often not used! In this case, if the Ack packet cannot be confirmed within the predetermined time, the transmitting terminal determines that the first receiving terminal has failed in receiving.
- Reference numeral 203 denotes a retransmission packet of the second packet, which has the same contents as the retransmission packet 103 of the second packet.
- an Ack packet 2031 is returned to the transmitting side, and re-retransmission is completed. If the number of retransmissions is unlimited, other terminals may not be able to use the first non-secured period, so it is better to limit the number of retransmissions. Also, it is more practical to set a retransmission time limit in order to suppress interference with other transmissions in the retransmission time itself using the first non-bandwidth reservation period. [Processing When Multiple Terminals Fail to Receive the Same Packet]
- each retransmission and retransmission (103, 203, 104, 204) all send the same data as the second multicast packet 101.
- a third retransmission request 302 may be transmitted before the transmission of the retransmission packet 103 and the retransmission packet 203 of the second packet. This may occur in the first non-secured period because the terminal transmitting the packet can freely transmit the packet, but there is no problem. Even in this case, the retransmission limit and the retransmission time limit can be applied in the same manner.
- FIG. 18 is an example in which the priority of the retransmission request packet is set to the next priority after the first to Nth multicast packets 100, 101, and 102.
- the priority is set to the highest priority compared to other packets in the non-secured period.
- the CPU 16 inputs these data to the AV processing means 43 via the internal bus 19.
- the AV processing means 43 processes the input data and displays the data on the display means 41.
- a memory means for temporarily storing a multicast data group higher than the Mac layer, and a sequence for assigning a sequence number to each of the multicast data groups for detecting data loss on the receiving side Numbering means, a wireless transmission means for transmitting data to which a sequence number has been assigned as a multicast packet of a bandwidth reservation type, and retransmission of multicast data for which omission has been detected on the wireless receiving side by using a sequence number.
- Retransmission control means that performs retransmission control of bandwidth-guaranteed multicast packets at a layer higher than the Mac layer, and performs retransmission control with lower priority and retransmission of broadcasts compared to bandwidth-reserved multicast packets. Therefore, it is possible to improve the reception probability by retransmission while transmitting bandwidth-secured multicast data with the highest priority. I can do it.
- a powerful retransmission process may be performed for the retransmission process of the retransmission request packet itself.
- the sequence in the non-bandwidth securing period in the first embodiment is further devised.
- all receiving terminals and transmitting terminals can transmit the necessary packets.However, if each receiving terminal transmits at an arbitrary time, packet collision occurs on the network. , Resend, resend, resend again.
- the types of packets to be transmitted include Internet site browsing request packets that are not limited to retransmission requests due to stream data reception failure, and various other types of packets.
- the stream data is required to be real-time, but other packets such as Internet browsing request packets do not need to be real-time. With such real-time characteristics, it must be avoided that packets are deprived of the transmission path and packets that require real-time characteristics are sent.
- the second embodiment is to improve such a point. Next, a configuration for realizing this will be described.
- FIG. 19 shows the configuration of the receiving terminal.
- the basic configuration is the same as that of the receiving terminal of the first embodiment shown in FIG. The difference is that the receiving terminal of this embodiment includes a normal data transmission buffer 51 and transmission timing adjusting means 52.
- the transmitting terminal includes a normal data transmission buffer and transmission timing adjusting means similar to the receiving terminal.
- Normal data transmission buffers 51 are provided with the number of priority levels of packets that need to be transmitted during the non-secured period.
- the transmission timing adjusting means 52 comprises as many normal data transmission buffers 51 as possible, and one transmission timing adjusting means 52 determines the transmission timing for one normal data transmission buffer 51.
- each transmission timing adjusting means 52 is composed of a random number generator 521, an upper limit setting section 522, a counter 523, a subtraction noise generator 524, and an AND circuit 525.
- the random number generator 521 Upon receiving the end notification of the band securing period, the random number generator 521 performs a process of generating a random number.
- the end notification of the band securing period can be obtained from the second timer means provided in the MAC processing means.
- the transmission terminal notifies the reception terminal all at once (FIG. 21). End notification 211).
- the random number generator 521 Upon receiving this notification, the random number generator 521 generates a random number once.
- each random number generator 521 has a structure in which an upper limit value is designated according to a priority level through an upper limit value setting unit 522, and generates random numbers within a range of the set upper limit value. The upper limit is minimized when the packet to be transmitted is a retransmission request packet.
- the initial setting value of the normal data transmission buffer other than the retransmission request is randomly selected from ⁇ 1 '' to ⁇ 32 ''
- the initial setting value of the normal data transmission buffer counter for transmitting the retransmission request is Is randomly selected from “1” to “8”. Instructing the upper limit value to the upper limit setting unit 522 as described above is performed by the CPU in the terminal.
- the random number generated by the random number generator 521 is set in the counter 523.
- the counter 523 counts down the pulse generated by the subtraction pulse generator 524 from the set value when the AND circuit 525 is in the gate open state, and outputs a timing signal when the count becomes 0.
- the timing signal is transmitted from the transmission timing adjusting means 52 to the corresponding transmission buffer via the data bus.
- the packet is sent to 51 and the packet stored in the buffer is transmitted.
- a signal indicating an idle period during which no packet flows in the network is added as a gate signal. Therefore, the countdown operation is performed only during the idle period.
- the state of the network is monitored by the wireless transmission means 18, and a signal indicating an idle period is obtained from the wireless transmission means 18.
- the subtraction pulse generator 524 divides the clock pulse in the terminal to an appropriate cycle and creates the clock pulse.
- FIG. 21 is a diagram illustrating an example of the normal data transmission timing in the non-bandwidth-amount period.
- the circled numbers indicate the counter values of the normal data transmission buffer of each wireless terminal (including the transmitting terminal and the receiving terminal). Each counter value is counted down every cycle T1 of the subtraction pulse.
- the time on the horizontal axis is schematically shown to make it easier to express the countdown state. The time T1 for counting down and the length of time required for transmitting retransmission requests and other normal data are not It is shown differently from the time length. Generally, the time required for normal data transmission is much longer than the period T1.
- each terminal has only one transmission buffer 51 and one transmission timing adjusting means 52!
- the transmitting terminal 3 broadcast-transmits the end notification 211 of the band securing period, the period thereafter becomes the non-band securing period.
- the receiving terminal 7 needs to transmit the retransmission request 412 for the stream data 312, and the receiving terminal 8 needs to transmit the retransmission request 413 for the stream data 313.
- the transmitting terminal 3 needs to transmit the normal data 512 and the receiving terminal 6 needs to transmit the normal data 511.
- the transmitting terminal 3 and the receiving terminal 6 randomly select the upper limit set value of the counter from "1" to "8" from among "1" to "8".
- the transmitting terminal 3 selects “12”, the receiving terminal 6 selects “6”, the receiving terminal 7 selects “3”, and the receiving terminal 8 selects “7” as the initial settings of the counter. Te ru.
- another wireless terminal After entering the non-secured period, another wireless terminal transmits a wireless frame to the wireless section and After confirming that there is no idle period, the transmitting terminal 3 and each receiving terminal count down the counter by one at the cycle of the subtraction pulse. Judgment of the idle period is made by measuring the received power to which the antenna power is also input, and when the received power is below the specified value, another wireless terminal transmits a radio frame. Is determined.
- the transmitting terminal 3 and each receiving terminal count down the counter the counter of the receiving terminal 7 first becomes 0, and the transmission right of the normal data is obtained.
- Receiving terminal 7 transmits retransmission request 102 to the wireless section immediately after the counter becomes zero.
- the counter values of the transmitting terminal 3 and the other receiving terminals 6, 8, and 80 are "9", "3", and "4", respectively.
- receiving terminal 7 While receiving terminal 7 is transmitting retransmission request 102, transmitting terminal 3, receiving terminals 6, 8, and 80 do not count down their counters.
- the receiving terminal 7 finishes transmitting the retransmission request 102 the idle period starts and the transmitting terminal 3, the receiving terminals 6, 8, and 80 again count down their counters.
- the receiving terminal 6 obtains the transmission right of the normal data and transmits the normal data 511 when the counter becomes 0.
- the receiving terminal 8 transmits the retransmission request 413, and the transmitting terminal 3 sequentially transmits the normal data 512.
- receiving terminal 8 transmits retransmission request 413 after normal data 511 transmitted by receiving terminal 6.
- the initial counter value that can be taken when transmitting a retransmission request S ⁇ 1 '' to ⁇ 8 '' the initial counter value that can be taken when transmitting other normal data
- the retransmission request will have the transmission right with a higher priority than other asynchronous data and will be transmitted first.
- the range of the counter initial setting value when transmitting the retransmission request is set to “1” to “4”, it is possible to transmit the normal data with higher priority than other normal data.
- the range of the initial value of the counter set when transmitting the retransmission request is flexibly set according to the condition of the wireless transmission path.
- This embodiment is an example in which the first embodiment is further developed. That is, in an actual transmission path, a plurality of transmission errors may occur, and in particular, the same receiving terminal may fail to receive a plurality of packets. In the first embodiment, in this case, a retransmission request may be transmitted for each packet for which reception has failed. In this embodiment, when one reception terminal fails to receive a plurality of packets, the number of retransmission requests is reduced to one.
- FIG. 22 is a time chart illustrating an example of a packet sequence of the wireless transmission device according to Embodiment 3 of the present invention.
- the same reference numerals are used for the same components as those in the time charts in FIGS.
- reference numeral 300 denotes a first retransmission request packet
- 3001 denotes an Ack packet transmitting a reception success acknowledgment of the first retransmission request packet 300
- 103 denotes a retransmission packet of a second packet
- 1031 denotes a second retransmission packet.
- 1041 is the Nack packet transmitting the reception failure confirmation of the Nth packet retransmission packet 104
- 204 is the re-retransmission packet of the Nth packet
- Reference numeral 2041 denotes an Ack packet that transmits a confirmation of successful reception of the retransmission packet 204 of the N-th packet.
- the first to Nth multicast packets are transmitted to the first to third receiving terminals.
- the first receiving terminal has failed to receive two packets, the first multicast packet 101 and the Nth multicast packet 102. Also, the Nth multicast packet 102 has failed to be received simultaneously by the first receiving terminal and the Nth receiving terminal.
- the receiving terminal performs an operation of transmitting a retransmission request packet to the transmitting terminal by using the first non-bandwidth reservation period.
- the first receiving terminal transmits the second multicast packet 101 and the Nth multicast packet out of the first to Nth multicast packets 100, 101, 102.
- One of the packets fails to be received, and the first retransmission request packet 300 is transmitted to the transmitting terminal using the first non-bandwidth reservation period.
- the retransmission request packet describes the retransmission request of the two failed packets.
- this embodiment will also be described with a configuration in which a retransmission request is made using a multicast packet.
- the transmitting terminal When the transmitting terminal receives the first retransmission request packet 300 normally, it returns an Ack packet 3001, which is a reception success confirmation, refers to the content of the retransmission request packet 300, and first retransmits the second packet.
- the packet 103 is transmitted to the first receiving terminal using a broadcast.
- the first receiving terminal Upon confirming the normal reception of the retransmitted packet 103 of the second packet, the first receiving terminal returns Ack 1031 to the transmitting terminal. Subsequently, the Nth multicast packet, which is the second reception failure packet, is transmitted to the first terminal.
- the receiving terminal has the configuration shown in FIG. 11, and receives the first to N-th multicast packets 100, 101, 102 via the antenna 21.
- the first to N-th multicast packets 100, 101, 102 are input to the wireless transmission means 18 and output to the internal bus 19 after the processing reverse to the transmission.
- the wireless transmission means 18 has the configuration shown in FIG. 8.
- the modulation applied at the time of transmission by the physical layer signal processing means 32 is demodulated, and the MAC packet shown in FIG. 10 is restored.
- the restored MAC packet is input to the MAC processing means 31, and the broadband indicated in the MAC header is transmitted.
- the MAC header is removed and output to the buffer means 29.
- the configuration of the buffer means 29 is the same as that described on the transmitting side as shown in FIG.
- the transmission buffer system is operated, but at the time of reception, the reception buffer system is operated.
- the MAC-processed packet is input from the reception data input terminal 41 and temporarily stored in the reception buffer means 40.
- the MAC processing means 30 controls the writing of the received data to the receiving buffer 40 via the control signal input / output terminal 42.
- the data stored in the reception buffer means 40 is output to the internal node 19 via the data transmission / reception means 34, the input / output terminals 33 and 28, and passed to the CPU 16.
- the data transmission / reception means 34 performs an operation of reading data from the reception buffer means 40 when the internal bus 19 is available and the CPU 16 can receive data.
- the CPU 16 writes the received data into the memory means 17, and at this time, determines whether or not the packet to be processed further is based on the IP header, the UDP header, and the identifier in FIG. . That is, the internal destination is determined by the IP header and the UDP header, and the multicast data to be stored in the memory is determined by using the identifier.
- FIG. 23 shows a data storage state in the memory 17.
- the capacity of storing the first to Nth multicast packet data is written into the memory means 17 in such a manner that it is possible to judge which sequence number of the packet data has dropped out at that time.
- the positions of the first to Nth multicast packet data in the memory are fixed, and whether the packet was normally received at the beginning of the combination of the sequence number + the multicast packet data and the normal writing was performed. Is attached. That is, by referring to the inside of the memory means 17, it is possible to determine which of the first to Nth multicast packet groups transmitted during the band securing period is missing.
- CPU 16 determines that the second multicast packet data and the Nth multicast packet data are missing, generates retransmission request packet 300, and prepares to transmit it to the transmitting terminal.
- FIG. 24 shows a configuration example of the retransmission request packet 300.
- the CPU 16 stores, in the payload portion of the IP header and the TCP header, an identifier indicating a retransmission request packet and a packet sequence number for performing the retransmission request. If there are multiple packets, store the number n of packets before the packet sequence, and store the n sequence numbers next.
- the retransmission request packet 300 is transferred to the wireless transmission means 18 via the internal bus 19.
- the retransmission request packet 300 is input to the buffer unit 29 via the input / output terminal 28.
- the buffer means 29 the retransmission request packet 300 input through the input / output terminal 33 is stored in the normal data transmission buffer means 37 in the data transmitting / receiving means 34, and the MAC processing is performed through the normal data output terminal 38. Pass by means 30.
- the MAC processing means 30 determines the first band non-securing period by the built-in second timer means 31, and when the first band non-securing period is reached, through the control signal input / output terminal 39.
- the normal data buffer means 37 is controlled, and the retransmission request packet 300 is read from the normal data buffer means 37.
- the read retransmission request packet 300 is subjected to modulation suitable for transmission by the physical layer signal processing means 32 after the MAC header is added thereto, and is transmitted by the antenna 21 to the transmitting terminal by unicast transmission.
- the determination of the bandwidth reservation period and the transmission timing may be made by using the first timer means 20 and inputting the same timing to the upper layer and the MAC layer.
- the transmitting terminal that has received the retransmission request packet 300 Upon confirming the normal reception of the wireless packet, the transmitting terminal that has received the retransmission request packet 300 returns an Ack packet 3001 to the first receiving terminal. Upon receiving the Ack packet 300 1, the first receiving terminal waits for retransmission of the packet that has made the retransmission request.
- the retransmission request packet is output to internal bus 19 in a process reverse to the transmission.
- the wireless transmission means 18 has the configuration shown in FIG. 8.
- the modulation applied at the time of transmission by the physical layer signal processing means 32 is demodulated, and the MAC packet shown in FIG. 24 is restored.
- the restored MAC packet is input to the MAC processing means 31, and when the address indicated in the MAC header is addressed to the own station, the MAC header is removed and output to the buffer means 29.
- the transmission buffer system was operated, but during reception, the reception buffer system was operated.
- a MAC-processed packet is input from a reception data input terminal 41 and stored in the reception buffer means 40.
- the MAC processing means 30 controls the input / output for the control signal. Through the input terminal 42, writing of received data to the receiving buffer 40 is controlled.
- the data once stored in the reception buffer means 40 is output to the internal bus 19 via the data transmission / reception means 34 and the input / output terminals 33, 28 and passed to the CPU 16.
- the data transmission / reception means 34 performs an operation of reading data from the reception buffer means 40 when the internal bus 19 is available and the CPU 16 is ready to receive data.
- the CPU 16 having received the data writes the received data into the memory means 17 At this time, the CPU 16 determines whether or not the packet to be subjected to the subsequent processing is determined from the IP header and the TCP header shown in FIG.
- the CPU 16 After performing the appropriate TCP / IP processing, the CPU 16 starts the operation of confirming the content of the payload. First, the identifier is checked, and if the identifier indicates a retransmission request for multiple packets, the number of subsequent packets and the stored packet sequence number are checked. Then, preparations are made to transmit the corresponding packet data. As shown in FIG. 7, the memory means 17 stores the data that has been previously transmitted by multicast transmission. Of these, the second multicast packet data and the N-th Resend data individually. That is, retransmission packet 103 of the second packet in FIG. 22 is transmitted to the first receiving terminal, and subsequently, retransmission packet 104 of the Nth packet is transmitted to the first receiving terminal. The retransmission packet is as shown in FIG.
- the transmission process is the same as the procedure of first performing multicast transmission in the first bandwidth reservation period, but since the priority of the retransmission packet is lower than the first, the transmission process is performed in the first non-bandwidth reservation period. Sent.
- the CPU 16 delivers the retransmission packet data transmitted during the first non-bandwidth-preservation period to the wireless transmission means 18 via the internal bus 19.
- the wireless transmission data input from the CPU 16 via the internal bus 19 and the input / output terminal 28 is input to the buffer means 29.
- the retransmission data of the second multicast packet input from the input / output terminal 33 is distributed to the normal data transmission buffer means 37 via the data transmission / reception means 34, and the data is transmitted to the normal data transmission buffer 37 in accordance with the radio transmission timing.
- the MAC processing means 30 manages a band securing period / non-bandwidth securing period and performs MAC protocol processing.
- the wireless transmission data is read out from the buffer means 29 at an appropriate timing and input to the physical layer signal processing means 32.
- the MAC processing means 30 determines that the time period is out of the band reservation by the second timer means 31 provided therein, and controls the buffer means 29 using the transmission control signal input / output terminal 39 during the period outside the band reservation. Then, the data is read out from the normal data transmission buffer means 37 and transmitted by multicast. The timing at which data is transferred from the CPU 16 to the buffer means is also determined by a control signal for controlling the normal data buffer means 37 and the data transmitting / receiving means 34 via the transmission control signal input / output terminal 39 by the MAC processing means 30 as a trigger. When the CPU 16 receives the data request, it transfers the data to the wireless transmission means 18. The determination of the band securing period and the transmission timing may be performed by using the first timer means 20 and inputting the same timing to the upper layer and the MAC layer.
- the MAC processing unit 30 that has received the data converts the data into a wireless MAC packet, and the wireless MAC packet is input to the physical layer signal processing unit 32, and the physical layer signal processing unit 32 is suitable for wireless transmission. After being modulated, it is transmitted wirelessly via antenna 21. Such transmission processing is performed twice: when transmitting the retransmission packet 103 of the second packet, and when transmitting the retransmission packet 104 of the Nth packet.
- a plurality of packet data requested to be retransmitted using retransmission request packet 300 is transmitted to the first receiving terminal.
- the first terminal that has received the retransmitted packet 103 of the second bucket and the retransmitted packet 104 of the Nth packet that has been retransmitted in this way returns an Ack packet, which is an acknowledgment packet, to the transmitting terminal. Re-receiving of the bucket that failed to be received ends.
- the retransmission packet itself of the second packet may be retransmitted as shown in FIG. .
- 204 is the retransmission packet of the Nth packet, which has the same content as the retransmission packet 104 of the Nth packet. If the packet is successfully received, an Ack packet 2041 is returned to the transmitting side, and the retransmission is completed. If the number of retransmissions is unlimited, other terminals may not be able to use the first non-secured period, so it is better to limit the number of retransmissions. In addition, the retransmission time itself using the first non-bandwidth-preserving period also reduces the retransmission time in order to suppress interference with other transmissions. It is more practical to set a time limit.
- a plurality of data may be combined and transmitted as in the retransmission packet 107 of the second packet + Nth packet in FIG. This reduces header overhead during retransmission.
- the payload part is stored after the identifier, such as packet number n, sequence number 1, data 1, sequence number 2, data 2, ... Is good. This is combined when the CPU 16 generates a retransmission packet.
- the CPU 16 inputs these data to the AV processing means 43 via the internal bus 19.
- the AV processing means 43 processes the input data and displays the data on the display means 41.
- the third receiving terminal fails to receive the N-th multicast packet, but uses the second retransmission request packet 301, ACk 3011, the N-th packet retransmission packet 104, and Ackl 041. Then, the same processing as that of the first embodiment is performed, and the retransmission processing is completed.
- a memory means for temporarily storing a multicast data group higher than the Mac layer, and a sequence number for detecting data loss on the receiving side is provided in each of the multicast data groups.
- a sequence number assigning means for assigning, a wireless transmission means for transmitting the data to which the sequence number has been assigned in a multicast packet of a band securing type, and a multicast data which is detected on the wireless receiving side by using the sequence number.
- Retransmission control means for retransmitting packets, and performs retransmission control of bandwidth-guaranteed multicast packets at a layer higher than the Mac layer.Retransmission control uses retransmission with a lower priority than bandwidth-reserved multicast packets.
- the receiving terminal fails to receive multiple multicast packets in the same bandwidth reservation period, a request for retransmission of multiple packets is made in one retransmission request packet. The amount can be reduced. Further, by combining and transmitting a plurality of retransmission packets, it is possible to reduce waste of the bandwidth of the retransmission packets. [0098] Although the retransmission processing of the retransmission request packet itself has not been described in the present embodiment, the retransmission processing may be performed.
- Embodiment 2 the configuration described in Embodiment 2 is employed during the non-bandwidth reservation period, and when a plurality of receiving terminals and transmitting terminals transmit a retransmission request packet or other normal packets. Therefore, arbitration of transmission timing can be performed.
- transmission of retransmission packets during the non-bandwidth reservation period is performed individually by broadcasting.However, during the bandwidth reservation period, a failure in receiving the same In this case, retransmission of the packet by multicast distribution is very inefficient.
- This embodiment is a technique suitable for dealing with such a case.
- FIG. 27 is a time chart illustrating an example of a packet sequence of the wireless transmission device according to Embodiment 3 of the present invention.
- the same reference numerals are used for the same components as those in the above time chart, and a part of the description is omitted.
- reference numeral 300 denotes a first retransmission request packet
- 3001 denotes an Ack packet transmitting a reception success confirmation of the first retransmission request packet 300
- 302 denotes a third retransmission request packet
- 3021 denotes a third retransmission.
- 108 is a retransmission packet of the second packet.
- transmission is performed by periodically and periodically switching between a band securing period and a non-band securing period.
- the N data groups are multicast-transmitted during the first bandwidth reservation period, and only data for which reception errors have occurred are retransmitted during the first non-bandwidth reservation period.
- the multicast distribution operation during the bandwidth securing period is the same as that of Embodiment 1 described above.
- the packet number of the failed reception and the receiving terminal are as shown in FIG.
- the operation of retransmission performed in a period will be described.
- the first receiving terminal and the second receiving terminal communicate with the first multi-user.
- Receiving cast packet 101 has failed.
- each receiving terminal performs an operation of transmitting a retransmission request packet to the transmitting terminal using the first non-bandwidth reservation period.
- the first receiving terminal and the second receiving terminal that have failed to receive the multicast packet respectively use the first non-bandwidth reservation period to individually transmit the first retransmission request packet 300 and the third transmission request packet.
- Send to the sending terminal In order to improve the reliability of the transmission of the retransmission request packet, the present embodiment will also be described with a configuration in which a retransmission request is performed using a unicast packet.
- the transmitting terminal When the transmitting terminal receives the first retransmission request packet 300 and the third retransmission request packet 302 normally, it returns Ack packets 3 001 and 3002, which are confirmations of successful reception. It is determined that both retransmission request packets request retransmission of the same second packet data by referring to the contents of (1). Then, the second packet data is transmitted using a multicast packet to a multicast group to which the first receiving terminal and the second receiving terminal belong in common.
- the first and second receiving terminals have the configuration shown in FIG. 11, and receive the first Nth multicast packets 100, 101, 102 via the antenna 21.
- the first to N-th multicast packets 100, 101, and 102 are input to the wireless transmission unit 18 and output to the internal bus 19 after the processing reverse to the transmission.
- the modulation applied at the time of transmission by the physical layer signal processing means 32 is demodulated, and the MAC packet in FIG. 10 is restored.
- the restored MAC packet is input to the MAC processing means 31, and when the broadcast address indicated in the MAC header is addressed to the broadcast group to which the own station belongs, the MAC header is removed and output to the buffer means 29.
- the buffer means 29 receives the MAC-processed packet and stores it in the reception buffer means 40. Further, at this time, the MAC processing means 30 controls the writing of the reception data to the reception buffer 40 via the control signal input / output terminal 42.
- the data once stored in the reception buffer means 40 is output to the internal bus 19 via the data transmission / reception means 34, the input / output terminals 33 and 28, and passed to the CPU 16.
- the data transmitting / receiving means 34 starts receiving when the internal bus 19 is available and the CPU 16 is ready to receive data.
- An operation of reading data from the buffer means 40 is performed.
- the CPU 16 having received the data writes the received data into the memory means 17
- the CPU 16 determines whether or not the packet should be processed after the IP header, the UDP header, and the identifier of FIG. That is, the internal destination is determined based on the IP header and the UDP header, and whether the multicast data to be stored in the memory is determined using the identifier.
- the CPU 16 determines that the second multicast packet data is missing, generates a retransmission request packet 300 or 302, and prepares to transmit it to the transmitting terminal.
- the CPU 16 stores an identifier indicating a retransmission request packet and a packet sequence number for performing a retransmission request in a payload portion of the IP header and the TCP header.
- This retransmission request packet 300 or 302 is transferred to the wireless transmission means 18 via the internal bus 19.
- the wireless transmission means 18 stores the retransmission request packet 300 in the normal data buffer means 37 in the buffer means 29 and passes it to the MAC processing means 30.
- the MAC processing means 30 determines the first non-securing period by the built-in second timer means 31, and when the first non-securing period is reached, the normal data for the normal data is transmitted via the control signal input / output terminal 39. It controls the buffer means 37 and reads out the retransmission request packet 300 or 302 from the normal data buffer means 37.
- the read retransmission request packet 300 or 302 After the read retransmission request packet 300 or 302 is attached with a MAC header, it is subjected to modulation suitable for transmission by the physical layer signal processing means 32, and is transmitted by the antenna 21 to the transmitting terminal by unicast transmission.
- the above-described processing is performed in the first receiving terminal for the retransmission request packet 300 and in the second receiving terminal for the retransmission request packet 302.
- the transmitting terminal that has received the retransmission request packet 300 Upon confirming the normal reception of the wireless packet, the transmitting terminal that has received the retransmission request packet 300 returns an Ack packet 3001 to the first receiving terminal. Upon receiving the Ack packet 300 1, the first receiving terminal waits for retransmission of the packet that has made the retransmission request. When the transmitting terminal receiving the retransmission request packet 302 confirms normal reception of the wireless packet, the transmitting terminal returns an Ack packet 3021 to the second receiving terminal. The first receiving terminal and the second receiving terminal Upon receiving the packets 3001 and 3021, it waits for the retransmission of the second multicast packet that has made the retransmission request.
- the retransmission request packet 300 or 302 When the retransmission request packet 300 or 302 is received via the antenna 21 inside the transmitting terminal, the retransmission request packet 300 or 302 is output to the internal bus 19 in a process reverse to the transmission.
- the modulation applied at the time of transmission by the physical layer signal processing means 32 is demodulated, and the MAC packet is restored.
- the restored MAC packet is input to the MAC processing means 31, and when the address indicated in the MAC header is addressed to the own station, the MAC header is removed and output to the buffer means 29.
- the buffer means 29 the packet subjected to MAC processing is input from the reception data input terminal 41, and is stored in the reception buffer means 40.
- the MAC processing means 30 controls the writing of received data to the receiving buffer 40 via the control signal input / output terminal 42.
- the data stored in the receiving buffer means 40 is output to the internal bus 19 via the data transmitting / receiving means 34 and the input / output terminals 33 and 28, and passed to the CPU 16.
- the data transmission / reception means 34 performs an operation of reading data from the reception buffer means 40 when the internal bus 19 is available and the CPU 16 can receive data.
- the CPU 16 that has received the data writes the received data into the memory means 17 At this time, the CPU 16 determines from the IP header and the TCP header whether or not the packet should be processed further.
- the CPU 16 compares the contents thereof and prepares for multicast transmission of the corresponding packet data. Since the memory means 17 stores the data that has been previously transmitted by multicast, the second multicast packet data for which retransmission has been requested is retransmitted by multicast. That is, in FIG. 27, the retransmission packet 108 of the second packet is transmitted to a multicast group to which the first receiving terminal and the second receiving terminal commonly belong.
- Retransmission packet 108 has the configuration shown in Fig. 10, and the payload portion has an identifier indicating that it is a retransmission packet, a sequence number, and data. This data part is the same as the second multicast packet data packet that first performed multicast transmission.
- the transmission process is the same as the procedure that first performed multicast transmission in the first bandwidth reservation period, but the priority of the retransmission packet is lower than the first, so it is transmitted in the first non-bandwidth reservation period .
- the CPU 16 delivers the retransmitted packet data transmitted in the first non-bandwidth reservation period to the wireless transmission means 18 via the internal bus 19.
- the wireless transmission data input from the CPU 16 via the internal node 19 and the input / output terminal 28 is input to the buffer means 29.
- the retransmission data of the second multicast packet input from the input / output terminal 33 is distributed to the normal data transmission buffer means 37 via the data transmission / reception means 34, and the normal data is transmitted in accordance with the radio transmission timing. Is input to the MAC processing means 30 via the output terminal 38.
- the MAC processing means 30 performs management of a bandwidth securing period / non-bandwidth securing period and MAC protocol processing, reads out radio transmission data from the buffer means 29 at appropriate timing, and inputs the data to the physical layer signal processing means 32 .
- the MAC processing means 30 determines that the time period is out of the band reservation by the second timer means 31 provided therein, and controls the buffer means 29 using the transmission control signal input / output terminal 39 during the period outside the band reservation. Then, the data is read from the normal data transmission buffer means 37 and transmitted by multicast.
- the timing at which data is transferred from the CPU 16 to the buffer means is also triggered by the control signal for controlling the normal data buffer means 37 and the data transmission / reception means 34 via the transmission control signal input / output terminal 39 by the MAC processing means 30. It is determined.
- the CPU 16 receives the data request, it passes the data to the wireless transmission means 18.
- the determination of the band securing period and the transmission timing may be performed by using the first timer means 20 and inputting the same timing to the upper layer and the MAC layer.
- the MAC processing means 30 that has received the data converts the data into a wireless MAC packet, and the wireless MAC packet is input to the physical layer signal processing means 32 and is adapted for wireless transmission by the physical layer signal processing means 32. After being modulated, it is transmitted wirelessly via antenna 21. In this way, the multicast transmission of the retransmission packet 108 of the second packet is performed.
- the data is transmitted to the first and second receiving terminals using multicast. Is done.
- the retransmission packet 108 of the second packet is a multicast packet transmission that does not use an Ack packet, if it is desired to improve reliability, the retransmission packet 108 may be repeatedly transmitted multiple times as shown in FIG.
- the first receiving terminal makes a retransmission request for the second multicast packet, 101 and the Nth multicast packet 102 in the first retransmission request packet 30.) 108 may be repeatedly transmitted by multicast.
- the first multicast packet 102 can be received without waiting for a retransmission request packet from another receiving terminal.
- the packet can be retransmitted.
- the third receiving terminal can receive a necessary retransmission packet without transmitting a retransmission request packet.
- the first retransmission request packet 300 is transmitted by multicasting.
- the other receiving terminals request which data other than their own terminal to retransmit. You can know if it is.
- the CPU 16 may determine whether to stop transmitting the retransmission request packet.
- the number of retransmissions of the retransmission request packet in FIG. 28 and FIG. 29 is preferably determined adaptively by the CPU 16 in accordance with the situation.
- the number of repetitions of the retransmission packet in FIGS. 28 and 29 is preferably determined adaptively by the CPU 16 according to the situation from the number of retransmissions of the past retransmission packet.
- the terminal that has failed in reception may transmit the retransmission request 301 again to reacquire part of the packet 110 (packet 104). At this time, the transmitting side can improve the reception probability by sending it by broadcasting.
- the CPU 16 inputs these data to the AV processing means 43 via the internal bus 19.
- the AV processing means 43 processes the input data and displays the data on the display means 41.
- a memory means for temporarily storing a multicast data group higher than the Mac layer, and a sequence for assigning a sequence number to each of the multicast data groups for detecting data loss on the receiving side Numbering means, a wireless transmission means for transmitting data to which a sequence number has been assigned as a multicast packet of a bandwidth reservation type, and retransmission of multicast data for which omission has been detected on the wireless receiving side by using a sequence number.
- Retransmission control means that performs retransmission control of bandwidth-guaranteed multicast packets at a layer higher than the Mac layer, and performs retransmission control by using retransmission with a lower priority than bandwidth-reserved multicast packets.
- Embodiment 2 the configuration described in Embodiment 2 is employed during the non-secured period, and a plurality of receiving terminals and transmitting terminals transmit retransmission request packets and other normal packets. When transmitting a packet, arbitration of transmission timing can be performed.
- the point of time when multicast transmission of retransmission packets is performed is the non-secured period.
- This embodiment employs a configuration in which a retransmission packet is transmitted in the next band securing period.
- transmission and reception of packets are performed by the transmitting terminal and the receiving terminal.
- packets are exchanged between the base station and the slave station.
- Adopt a configuration that Therefore, it should be noted that different terms are used from the above embodiment.
- the arbitration of the transmission timing described in the second embodiment is performed during the period outside the bandwidth reservation. It should be noted that the description may be duplicated in the second embodiment.
- FIG. 31 is a schematic diagram for explaining the wireless multicast retransmission method of this embodiment
- FIG. 32 is a diagram showing the configuration of a wireless network to which the method of FIG. 31 is applied.
- the wireless network 310 is composed of a multicast group 111 composed of a wireless base station 100 and wireless slave stations 101 to 104, a multicast group 112, and wireless slave stations 121 and 122. Connected by wireless LAN. Further, the wireless base station 100 is connected to a server for storing contents such as video and music using a wired network such as Ethernet or a high-speed serial bus such as IEEE1394.
- the wireless slave stations belonging to the multicast groups 111 and 112 can individually transmit and receive wireless frames to and from the wireless base station 100, in addition to receiving wireless frames distributed by multicast from the wireless base station 100.
- the wireless slave stations 121 and 122 can perform wireless communication with another wireless slave station via the wireless base station 100 or directly. The communication control of each wireless slave station, such as the transmission timing of these wireless frames, is performed by the wireless base station 100. [Configuration of wireless base station]
- FIG. 33 is a diagram showing a device configuration of the radio base station 100. The operation of the radio base station 100 will be described with reference to FIG.
- an input / output unit 320 is an interface with a wired network such as Ethernet or a high-speed serial bus such as IEEE1394, and exchanges stream data and asynchronous data with terminals connected thereto.
- the stream data transmission buffer 321 adds a stream data number and an error detection code to the stream data received by the input / output unit 320, converts the stream data into a radio frame, and stores it.
- the stream data stored in the stream data transmission buffer 321 is transmitted from the transmission unit 324 to the wireless section during the stream transmission period.
- the asynchronous data transmission buffer 322 adds an erroneous detection code to the asynchronous data input from the input / output unit 320, converts the data into a wireless frame, and stores the wireless frame.
- the asynchronous data transmission buffer 322 has the configuration shown in FIG. In FIG. 35, an asynchronous data transmission buffer 340 is the same as the asynchronous data transmission buffer 322 in FIG.
- the asynchronous data transmission buffer 340 includes an asynchronous data distribution unit 341 and a plurality of transmission queues (1) 342 to (N) 344.
- the asynchronous data distribution unit 341 sorts the asynchronous data received from the input / output unit 320 for each priority, and outputs the data to the transmission queues (1) 342 to (N) 344, and the transmission queues (1) 342 to (N) 344. Accumulates asynchronous data for each priority order.
- the back-off control section 323 prepares a counter for each of the transmission queues (1) 342 to (N) 344.
- an initially set value is inserted into a counter with a natural number selected at random, and during the asynchronous transmission period, It counts down every predetermined time T1, and when the counter reaches 0, the asynchronous data stored in the transmission queue is transmitted from the transmission unit 324 to the radio section.
- Transmitting section 324 performs digital modulation such as multi-level phase modulation or multi-level quadrature amplitude modulation on stream data or asynchronous data, converts the stream data or asynchronous data into a high-frequency band analog signal, and transmits the analog signal to a wireless section.
- the receiving unit 325 converts an analog signal, which has also received antenna power, into a baseband digital signal and performs digital demodulation.
- the error detection unit 326 detects whether there is any transmission error in the digitally demodulated received data, and if an error occurs, stores the data in the reception buffer 327.
- the reception buffer 327 discriminates the received data, and transfers the received data to the retransmission control unit 328 if the request is a retransmission request, or to the input / output unit 320 if the data is other data.
- retransmission control section 328 instructs stream data transmission buffer 321 to retransmit the specified stream data.
- FIG. 34 is a diagram showing a device configuration of a wireless slave station. The operation of the wireless slave station will be described with reference to FIG.
- an input / output unit 330 is an interface for exchanging stream data and asynchronous data.
- the stream data transmission buffer 331 adds a stream data number and an error detection code to the stream data input from the input / output unit 330, converts the stream data into a wireless frame, and stores it.
- the stream data stored in the stream data transmission buffer 331 is transmitted from the transmission section 334 to the radio section under the control of the radio base station 1100 during the stream transmission period. It should be noted that the stream data transmission buffer 331 is not required for a wireless slave station that does not transmit stream data.
- the asynchronous data transmission buffer 332 adds an error detection code to the asynchronous data input from the input / output unit 330 and the retransmission request input from the retransmission request unit 338, converts the data into a radio frame, and stores the radio frame.
- FIG. 35 shows the detailed configuration of the asynchronous data transmission buffer 340 of the wireless slave station as well as the wireless base station.
- the asynchronous data transmission buffer 340 is the same as the asynchronous data transmission buffer 332 in FIG.
- the asynchronous data transmission buffer 340 includes an asynchronous data distribution unit 41 and a plurality of transmission queues (1) 342 to (N) 344.
- the asynchronous data distribution unit 341 sorts the asynchronous data received from the input / output unit 330 and the retransmission request input from the retransmission request unit 338 for each priority, and outputs them to the transmission queues (1) 342 to (N) 344. I do. Here, assuming that the transmission queue (1) 342 has the highest priority, the retransmission request is accumulated in the transmission queue (1) 342, and the other asynchronous data has the priority in the transmission queue (2) 343 to (N) 344. Non-sequentially stored every time. In FIG. 34, the back-off control unit 333 prepares a counter for each of the transmission queues (1) 342 to (N) 344.
- Transmitting section 334 performs digital modulation such as multi-level phase modulation or multi-level quadrature amplitude modulation on stream data or asynchronous data, converts the stream data or asynchronous data into a high-frequency band analog signal, and transmits the analog signal to a wireless section.
- digital modulation such as multi-level phase modulation or multi-level quadrature amplitude modulation
- the receiving unit 335 converts the analog signal, which has also received the antenna power, into a baseband digital signal and performs digital demodulation.
- Error detection section 336 detects whether there is a transmission error in the received data subjected to digital demodulation, and notifies retransmission request section 338 if there is a transmission error. When a transmission error occurs, it is stored in the reception buffer 337.
- the reception buffer 337 discriminates the received data, and if it is stream data, reconstructs the stream data in numerical order and delivers it to the input / output unit 320.
- the retransmission request unit 338 configures a retransmission request frame and stores it in the asynchronous data transmission buffer 332 to notify the radio base station 1100 of the number of the radio frame detected by the error detection unit 336.
- the video content now stored in the server 130 is distributed to the wireless slave stations 101 to 104 belonging to the multicast group 111 via the wireless base station 100.
- the wireless base station 100 divides the video content from the server 130 into a plurality of stream data, receives the stream data, adds a stream number to the received stream data, converts the stream data into a wireless frame, and distributes the multicast to a multicast group 111.
- the vertical direction indicates the passage of time from top to bottom
- the horizontal direction shows the transmission and reception of wireless frames composed of stream data and asynchronous data between wireless terminals.
- the time is divided for each predetermined time cycle, and within each time cycle, a stream transmission period corresponding to the bandwidth securing period of the above-described embodiment is performed. (Corresponding to the band securing period of the above-described embodiment) and an asynchronous transmission period (corresponding to the band securing period of the above-described embodiment).
- the wireless base station 100 or one of the wireless slave stations transmits stream data, such as video and audio, which need to secure a wireless band in advance and transmit. It is not possible for the radio station to transmit and transmit radio frames freely.
- the wireless base station 100 or any wireless slave station transmits asynchronous data that does not require isochronism, such as Internet data, without control from the wireless base station 100.
- the length of the stream transmission period is determined by the amount of stream data that needs to be transmitted within a predetermined time. However, the time is limited by the wireless base station 100 to a predetermined time or less so that the wireless transmission path is not occupied by the stream transmission period.
- the radio base station 100 determines the time length of the stream transmission period according to the amount of stream data transmitted by the server 130, and broadcasts the beacon 210 at the beginning of the time cycle. Notify all wireless slave stations.
- the beacon 210 also includes the end time of one cycle, that is, the transmission time of the next beacon 220. Further, at the end of the stream transmission period, the radio base station 100 broadcast-transmits the end notification 211 of the stream transmission period, and notifies all wireless slave stations that the period is the asynchronous transmission period thereafter.
- the beacon 220 is broadcasted at the beginning of the stream transmission period, and the end notification 221 is broadcasted at the end of the stream transmission period. Thereafter, by repeating this operation, all the radio stations can know the start and end of the stream transmission period and the asynchronous transmission period.
- the end of the stream transmission period is notified to all the wireless slave stations by the radio base station 100 broadcasting the end notifications 211 and 221.
- the stream transmission period is transmitted to the beacons 210 and 220.
- Embedded end time information for Notifying all wireless slave stations the wireless slave station operates based on the end time information of the stream transmission period embedded in the beacons 210 and 220, and performs operations during the asynchronous transmission period after that time. Is also good.
- the wireless base station 100 converts the stream data divided and transmitted from the server 130 into wireless stream data 310 to 31N, and multicasts the wireless stream data sequentially between wireless sections.
- the radio base station 100 adds a stream data number and an error detection code when converting to radio stream data.
- the wireless slave stations 101 to 104 detect errors in the stream data 310 to 31N for transmission errors.
- the wireless slave station 102 detects a transmission error in the stream data 312, and the wireless slave station 103 detects a transmission error in the stream data 313.
- the wireless slave station 102 In order to have the wireless base station 100 retransmit the stream data 312, the wireless slave station 102 creates a retransmission request frame in which information indicating that the stream data 312 cannot be received normally is embedded. And prepare for transmission to the wireless base station 100. Similarly, in order to have the wireless base station 103 retransmit the stream data 313 to the wireless base station 100, the wireless base station 100 creates a retransmission request frame in which information indicating that the stream data 313 cannot be received properly is embedded, and the wireless base station 100 Prepare to send to local office 100.
- the wireless child station 102 detects an error in the stream data 312, it cannot be determined that the stream data 312 cannot be normally received. Therefore, since the wireless child station 102 normally receives the stream data 311 and the stream data 313 sequentially transmitted from the wireless base station 100, it can know that the stream data 312 is missing.
- the wireless slave station 102 detects a reception error in the stream data 312 because the information that the stream data 312 is missing and an error in the stream data originally received in the order in which the stream data 312 is received are detected. Judge that.
- the wireless base station 100 and the wireless slave stations 101 to 104 are the operation of the wireless base station 100 and the wireless slave stations 101 to 104 during the stream transmission period.
- the operation during the asynchronous transmission period after the wireless base station 100 transmits the end notification 211 of the stream transmission period will be described. I do.
- the wireless base station 100 and all other wireless slave stations belonging to the wireless network 10 transmit asynchronous data at their own transmission timing without being controlled by the wireless base station 100. .
- the radio base station 100 or another radio station transmits the asynchronous data in a random manner, the transmission start timing of the asynchronous data competes and collides in the radio section, so that a transmission error occurs. appear.
- the radio base station 100 and all the radio child stations belonging to the network 10 each hold a counter for individually determining the transmission start timing.
- this counter is randomly selected from natural numbers within a predetermined range and set as an initial value, and the counter is set to 1 every predetermined time T1. Count down each time, and start sending asynchronous data when it reaches 0.
- the range of the value set as the initial value of the counter is such that a statistically optimum value can be determined from the number of wireless terminals belonging to the network 10 and the amount of asynchronous data transmitted to the wireless section. I do.
- the predetermined time T1 is set to be equal to or longer than a time at which it is possible for another terminal to transmit a radio frame during T1 and to check whether or not it is possible.
- the wireless slave station has one or more asynchronous data transmission buffers therein, and has the counter for each asynchronous data transmission buffer.
- a wireless station requesting retransmission of stream data must have at least two asynchronous data transmission buffers.
- the maximum value of the range that can be taken by the initial value of the counter of the asynchronous data transmission buffer for transmitting the retransmission request is the counter of the other asynchronous data transmission buffer. It shall be smaller than the maximum value of the range that the initial setting value can take.
- the initial value of the counter of the asynchronous data transmission buffer other than the retransmission request is randomly selected from “1” to "32”
- the initial value of the counter of the asynchronous data transmission buffer for transmitting the retransmission request is Is randomly selected from "1" to "8”.
- FIG. 36 is a diagram showing an example of asynchronous data transmission timing during this asynchronous transmission period.
- the circled numbers indicate the counter values of the asynchronous data transmission buffer of each wireless terminal. Further, each counter value is counted down every predetermined time T1.
- the countdown of the counter is easy to understand.
- the time in the horizontal axis direction represents an outline, and the time T1 for counting down and the time required for transmitting a retransmission request or other asynchronous data are different from the actual time length. In general, the time required for transmitting asynchronous data is much longer than the predetermined time T1.
- an asynchronous transmission period follows.
- the wireless slave station 102 needs to send a retransmission request 412 for stream data 312, and the wireless slave station 103 needs to send a retransmission request 413 for stream data 313.
- the base station 100 needs to transmit the asynchronous data 512 and the wireless slave station 101 needs to transmit the asynchronous data 511.
- the counter initial setting value is randomly selected if the radio base station 100 and the radio slave station 101 are in the range of “1” to “32”, and the radio slave station is in the range of “1” to “8”.
- the wireless base station 100 selects “12”, the wireless slave station 101 selects “6”, the wireless slave station 102 selects “3”, and the wireless slave station 103 selects “7” as the initial settings of the counter. do it! /
- another wireless terminal After entering the asynchronous transmission period, another wireless terminal transmits a wireless frame in the wireless section, confirms that the idle period is present, and confirms that the wireless base station 100 and the wireless slave stations 101 to 10 3 counts down the counter by one every time T1.
- the idle period is determined by measuring the received power input from the antenna, and if the received power is less than the specified value, another wireless terminal transmits a radio frame. Judge that there is.
- the counter of the wireless slave station 102 first becomes 0, and the transmission right for asynchronous data is obtained. As soon as the counter reaches 0, the wireless station 102 transmits a retransmission request 102 to the wireless section.
- the counter values of the wireless base station 100, the wireless slave station 101, and the wireless slave station 103 are “9”, “3”, and “4”, respectively.
- the wireless slave station 102 While the wireless slave station 102 is transmitting the retransmission request 102, the wireless base station 100, the wireless slave station 101, and the wireless slave station 103 do not count down their counters.
- the idle period starts and the wireless base station 100, the wireless slave station 101, and the wireless slave station 103 count down their counters again.
- the counter becomes 0 when the wireless slave station 101 obtains the right to transmit asynchronous data and transmits the asynchronous data 511. Send.
- the wireless slave station 103 transmits the retransmission request 413, and the wireless base station 100 sequentially transmits the asynchronous data 512.
- the asynchronous data 512 transmitted by the wireless base station includes an Ack response to the retransmission request to which the wireless local station has also been sent.
- wireless slave station 103 transmits retransmission request 413 after asynchronous data 511 transmitted by wireless slave station 101.
- the counter initial set value S "1" to “8” that can be obtained when transmitting a retransmission request and the counter initial set value S "1" that can be obtained when transmitting other asynchronous data As long as the value is up to “32”, the retransmission request will acquire the transmission right with a higher priority than other asynchronous data, and will be transmitted first. Further, if the range of the counter initial setting value when transmitting a retransmission request is set to “1” to “4”, it becomes possible to transmit data with higher priority than other asynchronous data.
- the range of the initial value of the counter set when transmitting a retransmission request is flexibly set according to the conditions of the wireless transmission path.
- the wireless base station 100 broadcasts the beacon 220 again, and the stream transmission period starts.
- the radio base station 100 has received the retransmission request 412 of the stream data 312 from the radio slave station 102 and has received the retransmission request 413 of the stream data 313 from the radio slave station 103. . Therefore, the wireless base station 100 multicast-retransmits the stream data 312 and the stream data 313 at the beginning of the stream transmission period. Since the wireless slave stations other than the wireless slave station 102 have already received the stream data 312 normally, the wireless slave stations discard the retransmitted stream data 312 even if they are received without error.
- the radio station 10 Since the wireless slave stations other than 3 have already received the stream data 313 normally, they discard the retransmitted stream data 313 even if they receive it without error. The retransmission of the stream data in which the transmission error has occurred is completed as described above.
- the wireless station 101 transmits the retransmission request 421 to the wireless base station 100 during the asynchronous transmission period.
- Request 321 retransmission.
- the wireless base station 100 cannot know the information that the stream data has been normally received from the wireless stations 101 to 104, it is necessary to hold the stream data. Therefore, if there is no request for retransmission of stream data from the wireless stations 101 to 104 for a predetermined time, the stream data is discarded. For example, it is determined that the stream data 311 will be discarded 300 ms after the first transmission. In this case, it is necessary for the radio base station 100 to prepare a transmission buffer for holding 300 ms of stream data. As another method, if the radio base station 100 does not receive a retransmission request from the radio mobile stations 101 to 104 during a predetermined cycle, all stream data transmitted before the predetermined cycle will be transmitted to the radio mobile stations 101 to 104. 104 discards the transmission buffer power assuming that it has been received normally.
- a non-bandwidth securing period is provided next to the bandwidth securing period, during which a retransmission request and a retransmission packet in response to the request are transmitted.
- Multicast distribution of stream data can be performed even if there is no separate external period, and if reception fails in that distribution, a retransmission request can be made, and reception failure The goal is achieved if the retransmission of such packets can be done without delay.
- This embodiment shows an example in which such a band period and an out-of-band period are not provided.
- FIG. 37 is a time chart showing a packet sequence example of the wireless transmission apparatus according to the sixth embodiment.
- FIG. 37 The components in FIG. 37 are the same as the components in the first embodiment and the like, and a description thereof will be omitted. Also, the configurations of the transmitting terminal and the receiving terminal are the same as those described in the first embodiment, and a description thereof will not be repeated.
- Fig. 38 shows an example of how to assign priorities. 500 is the highest priority packet, 501 is the second priority packet, 502 is the third priority packet, and 504 is the low priority packet.
- the horizontal axis is the time axis, and the waiting time from the end of the busy period, that is, the period during which the previous wireless packet is being transmitted, to the time when the packet can be transmitted differs according to the priority of the knocket.
- the highest priority packet 500 has a short latency T1
- the second priority packet 501 has the next low latency T2
- the third priority packet 502 has the next low latency T3
- the lowest priority packet 503 has the longest latency.
- packet transmission becomes possible. As described above, by controlling the transmission waiting time, transmission priority can be given.
- the counting of the waiting time starts, When the time Tl is reached, if there is a first priority packet to be transmitted, the transmission is performed. If the first priority packet does not exist, the time counting is continued without transmission. Then, when the time reaches T2, if there is a second priority packet to be transmitted, the transmission is performed. If it does not exist, the calculation of the waiting time is continued, and when the time reaches T3, the third packet is transmitted if it exists.
- a period such as a band securing period is not provided, but a high priority packet is transmitted preferentially by providing a large or small waiting time according to the priority.
- the next-priority packet is started after all the higher-priority packets have been transmitted, and the transmission sequence is the same as the bandwidth securing period and the non-bandwidth securing period. I have.
- the first to N-th multicast packets are set to the first priority packet, and the retransmission request packet and the retransmission packet are set to the second priority packet.
- the packet may be the first priority packet
- the retransmission request packet may be the second priority packet
- the retransmission packet may be the third priority packet.
- the priority level is different, so that the buffer means provided in the transmitting terminal cannot store the third packet if it has the two transmitting buffers shown in FIG.
- the transmission of the retransmission packet which is the third priority packet, has the transmission buffer configuration shown in FIG. 39, and a low-priority data buffer means 400 and a low-priority data output terminal 401 are added.
- the priority may be such that first priority ⁇ second priority ⁇ third priority.
- the priority of the retransmission request packet and the priority of the retransmission packet may be reversed.
- the retransmission control uses the second priority packet and performs retransmission at a lower priority than the multicast packet. Therefore, while transmitting multicast data with the highest priority, the next priority packet is transmitted. Retransmission can improve the reception probability.
- a force retransmission process may be performed without touching the retransmission process of each broadcast packet.
- the length of the waiting time is set in accordance with the priority.
- different random numbers equal to or less than the upper limit different according to the priority are assigned.
- the value it is possible to adopt a configuration in which a pulse such as a clock pulse is down-counted, and when it becomes zero, transmission is possible.
- a random number with an upper limit of 3 or less is assigned to each packet of the first priority packet group, and a random number with an upper limit of 7 or less is assigned to each packet of the second packet group.
- a random number with an upper limit of 31 or less is assigned to each packet in the packet group of 3.
- random numbers are not assigned to packets, but are assigned to the buffer that stores the packet. For convenience of explanation, we will assign random numbers to packets. Each packet counts down only while the net is not busy, and starts transmitting when it reaches zero.
- the countdown for the random number assigned to the second multicast packet 101 is performed at the time when the transmission of the first multicast packet 100 is completed.
- the countdown for the random number assigned to the third multicast packet is performed simultaneously with the end of the transmission of the second multicast packet. That is, in the first priority packet group, the countdown from the random number for the (N + 1) th multicast packet is started when the transmission of the Nth multicast packet ends.
- the countdown of the random number for the retransmission request packet starts from the time when the retransmission request is generated. If the request is a retransmission request of the first multicast packet, the time when the reception failure of the packet is detected is also determined. In the case of a retransmission packet, the power at the time of receiving the retransmission request is also increased. Similarly, the third priority packet group also starts when the transmission of the packet is requested.
- the band securing period and the non-band securing period are cyclically repeated, and the retransmission of the packet for which transmission has failed is performed in the non-band securing period or the band securing period of the next cycle.
- the cyclic repetition period is assumed to be the time length required for transmitting and receiving the retransmission request packet and the retransmission packet. However, how many packets fail to transmit varies depending on the situation, and is not constant in each cycle.
- FIG. 40 is a configuration diagram of the multicast communication system according to Embodiment 7 of the present invention.
- reference numeral 1401 denotes a master station
- 1402-1405 denote slave stations. These are all installed in the home.
- the master station 1401 and the slave stations 1402 are installed in a living room
- the slave stations 1403 to 1405 are installed in a kitchen, a children's room, and a bedroom, respectively.
- Reference numerals 1411 to 1415 denote high-definition video / audio streams
- reference numeral 1416 denotes a wireless signal compliant with IEEE802.11a, including a multicast distribution signal of the high-definition video / audio stream 1411.
- Reference numeral 1430 denotes a video / audio server that outputs the high-definition video / audio stream 1411, and is provided inside the master station communication device 1401.
- Reference numeral 1431 denotes a master station communication device which receives the high definition video / audio stream 1411 and outputs a radio signal 1416 compliant with the IEEE802.11a, and is provided inside the master station 1401.
- Reference numerals 1432 to 1435 denote slave station communication devices to which the wireless signal 1416 conforming to the IEEE802.11a is input and which output the high-definition video / audio streams 1412 to 1415, respectively, and the slave stations 1402 to 1405, respectively. Provided inside.
- Reference numerals 1442 to 1445 denote televisions to which the high-definition video / audio streams 1412 to 1415 are input, and which reproduce the video and audio of the i-vision.
- FIG. 41 is a diagram showing the internal configuration of the master station communication device 1431, which includes a buffer 14152, a radio unit 14155, a transmission confirmation processing unit 14156, a multicast retransmission processing unit 14157, and a multicast retransmission processing unit 14158. And a multicast distribution processing unit 14159.
- the buffer 14152 is an element for temporarily storing the video / audio packet.
- the stored packet is associated with a sequence number so that a packet whose transmission has failed can be detected.
- the multicast retransmission processing unit 14157 and the multicast retransmission processing unit 14158 are functional units that perform processing for creating and retransmitting a packet whose transmission has failed. There are two reasons for performing the retransmission processing, the broadcast retransmission processing unit and the multicast retransmission processing unit, which will be described later. Note that the terms of multicast and multicast have already been described in the previous embodiment, and a description thereof will be omitted.
- the multicast distribution processing unit 14159 is a functional part that performs processing for multicast distribution of a new video bucket stored in the buffer.
- the transmission confirmation processing unit 14156 is a part that confirms the transmission of the multicast-distributed packet to each slave station, receives a response packet, and detects which packet has failed transmission.
- the wireless unit 14155 is a functional unit that receives a packet from each of the above-described processing units and transmits the packet to the slave station, or receives a packet from the slave station and transmits the packet to a required processing unit. A more detailed description of each of these parts will be described later, and before that, each signal and packet in FIG. 41 will be described.
- the video / audio data packet 14101 is a packet received from the video / audio server 1430.
- the payload stores the high-definition video / audio stream 1411 for a predetermined size.
- the radio transmission signal 14118 and the radio reception signal 14119 are transmitted and received from the radio section 14155. And a wireless signal 1416 conforming to the IEEE802.11a.
- FIG. 42 shows a frame configuration of the wireless signal 1416 based on the IEEE802.11a.
- 14300 is a beacon
- 14301 is a multicast signal
- 14302 is a broadcast signal.
- the beacon 14300 is a wireless transmission signal 14118 of the wireless signal 1416 compliant with the IEEE802.11a, and is a control block placed at the head of a frame.
- the multicast signal 14301 is the wireless transmission signal 14118 of the wireless signal 1416 compliant with the IEEE802.11a, and relates to the multicast distribution data packet 14112 and the multicast retransmission data packet 14113. It is composed.
- the broadcast signal 14302 includes a transmission acknowledgment inquiry packet 14114, a transmission acknowledgment response packet 14110, and a broadcast retransmission data packet 14115.
- the transmission confirmation inquiry packet 14114 and the broadcast retransmission data packet 14115 are the wireless transmission signal 14118 of the wireless signal 1416 based on the IEEE802.11a, and Regarding the transmission confirmation response packet 14110, among the radio signals 1416 conforming to the IEEE802.11a, with respect to the radio reception signal 14119, that is, the radiocasting of the IEEE802.11a standard, the receiving side: If the reception is successful without error, the ACK is replied.If the ACK is not received, the transmitting side retransmits the ACK. Both 14118 and the radio reception signal 14119 will be mixed and used.
- the frame period of the wireless signal 1416 (the time between a certain beacon 14300 power and the next beacon 14300) conforming to the IEEE802.11a is set to 1 second.
- the time required for transmitting the beacon 14300 is sufficiently small for one second and can be ignored.
- the notifier 14152 includes a sequence number generation unit 14201, a connection ⁇ 14202, a case ⁇ 14203, a search ⁇ 14204, and an extraction ⁇ 14205, ing.
- a sequence number is generated by the sequence number generation unit 14201, and the combining unit 14202 adds the sequence number to the received video / audio data packet.
- the search unit 14204 sequentially stores the video and audio data packets 14101 in the storage unit 14203, and searches for the sequence number 103 sent from the multicast retransmission processing unit, the multicast retransmission processing unit, and the multicast distribution processing unit out of the stored audio / video data packets 14101.
- the storage unit 14203 searches for a packet that matches the number, and if there is a match, the extraction unit 14205 extracts it as a transmission data packet 14102 and outputs it to the request destination.
- the buffer 14152 includes transmission information 14105 indicating that transmission / reception has been completed or untransmitted power for the audio / video data packet 14101 to be stored, and to which slave station communication device On the other hand, the transmission information 14106 indicating whether or not a transmission failure has occurred is stored and output as transmission transmission information 14104 each time it is input.
- FIG. 50 is a flowchart for explaining the operation performed by the buffer 14152 described above. This step is a step of determining whether or not a force is applied to the diamond-shaped block if the conditions are satisfied, and a step of performing processing by a rectangular block. Since the contents of the judgment and processing are described in each block, a series of processing can be understood by following the steps in order from the start. Therefore, further description of FIG. 50 is omitted here.
- the radio unit 14155 includes a MAC processing unit 14161, a physical processing unit 14162, a timer 14163, and a beacon generation unit 14164.
- the MAC processing unit 14161 and the physical processing unit 14162 perform processing on the MAC layer and the physical layer of IEEE 802.11a as described in the above embodiments. That is, a MAC header is added to the head of the packet to be sent to the outside, and the MAC header is removed from the packet received from the outside, and the packet is transferred to the transmission confirmation processing unit 14156.
- the packets sent to the outside are a transmission confirmation inquiry packet, a multicast distribution data packet, a multicast retransmission data packet, a multicast retransmission data packet, and a beacon.
- Packets other than the beacon are transmitted by the transmission confirmation processing unit 14156, It is sent from the multicast distribution processing unit 14159, the multicast retransmission processing unit 14158, and the multicast retransmission processing unit 14157.
- the beacon is generated by built-in beacon generating means 14164.
- the generation timing of the beacon generation means 14164 is controlled by a timer 14163. In this embodiment, it is set to one second.
- the beacon generation means 14164 activates the beacon timing signal at the same time as generating the beacon.
- the transmission confirmation processing unit 14156 basically performs the following three processes, and will be described with reference to the flowchart shown in FIG.
- the step numbers in Katsuko correspond to the steps in FIG.
- the broadcast retransmission processing unit 14157 basically executes the following four processes, and will be described with reference to the flowchart in FIG.
- the transmission data packet 14102 that failed to be transmitted is extracted from the buffer 14152, and the address of the corresponding slave station communication device is added in accordance with the transmission transmission information 14104, and the data is wirelessly transmitted as the retransmission data packet 14115.
- Output to the unit 14155 (S526). This is performed in a range that satisfies the upper limit of the number of broadcast retransmissions (S526 ⁇ 525). In this case, the number of the slave station communication devices for which transmission failed is small! ⁇
- the transmission data packet 102 is retransmitted to the radio unit 14155 in order from the transmission data packet 102.
- the upper limit is exceeded, the retransmission of the broadcast stops, and the process returns to the beginning (S521).
- the broadcast retransmission processing unit 14157 sets the upper limit of the number of retransmitted multicasts to 20 packets. However, since the remaining time of a frame changes every frame, the upper limit of the number of broadcast retransmissions is calculated every frame.
- the multicast retransmission processing unit 14158 basically performs the following three processes, and will be described with reference to the flowchart of FIG.
- the state of the state is determined.
- the transmission data packet 102 is extracted, added with a multicast address, and output to the radio unit 14155 as the multicast retransmission data packet 113 (S535).
- the transmission data packets are transmitted in descending order of the number of slave station communication devices that failed to transmit.
- the multicast retransmission processing section 158 sets the upper limit of the number of multicast retransmissions to 990 packets. This value does not change for each frame unless the frame period is changed or the transmission confirmation securing time is changed.
- the multicast distribution processing unit 14159 basically performs the following two processes.
- the transmission information writing completion flag 14122 becomes active (S541), and after lsec (S542), by specifying the sequence number 14103 of the untransmitted transmission data packet 14102 according to the transmission information 14104.
- the untransmitted transmission data packet 102 is extracted from the buffer 14152, added with a multicast address, and output to the radio unit 14155 as the multicast distribution data packet 112 (S543 to S547).
- the beacon timing signal 14121, the transmission confirmation ensuring time, and the multicast retransmission number 14117 are also received by each component, and the maximum time available for multicast distribution in the frame is determined. Calculate and set the maximum number of multicast distributions It is determined (S543). An example will be described in which this upper limit is determined.
- the transmission confirmation securing time is a fixed value for securing the time required for the transmission confirmation, and is set to 10 msec as described above.
- the beacon interval was 1 second, and the time required for transmitting one packet of the transmission data packet 14102 by multicast was 1 msec.
- the multicast distribution processing unit 14159 sets the upper limit of the number of multicast distribution to 490 packets.
- the upper limit of the number of multicast transmissions is calculated every frame.
- distribution processing of up to 490 packets per frame is permitted. If the power of the untransmitted transmission data packet 14102 that is actually stored in the buffer 14152 is less than that, the number becomes the number. For example, if the number of untransmitted transmission data packets 14102 is only 10 packets, a 10-packet distribution process is performed (S546). Then, the fact that the relevant video / audio data packet 101 has been transmitted is written to the buffer 14152 as transmission information 105.
- FIG. 45 is an internal configuration diagram of the slave station communication devices 1432 to 1435.
- 14201 is a video / audio data packet
- 14202 is a data packet
- 14206 is reception information
- 14210 is a transmission confirmation response packet
- 14214 is a transmission confirmation inquiry packet
- 14218 is a radio transmission signal
- 14219 is a radio reception signal.
- the video / audio data packet 14201 includes the HD video / audio stream 1412.
- the wireless transmission signal 14218 and the wireless reception signal 14219 constitute a wireless signal 1416 compliant with the IEEE802.11a.
- a buffer 14252 receives the data packet 14202 and the reception information 14206, and outputs the video / audio data packet 14201 and the reception information 14206.
- the buffer 14252 stores the data packets 14202 in sequence number order, and sequentially outputs them as video and audio data packets 14201 in sequence number order while removing the sequence numbers.
- the buffer 14252 stores and outputs the reception information 14206 indicating whether or not the data packet 14202 to be stored has been stored for each sequence number.
- a radio unit 14255 receives the radio reception signal 14219 and the transmission acknowledgment packet 14210, and outputs the transmission acknowledgment inquiry packet 14214 and the data packet 14202.
- the wireless unit 14255 outputs the transmission confirmation inquiry packet 14214 as the wireless transmission signal 14218.
- radio section 14255 extracts the portion and outputs it as transmission confirmation inquiry packet 14214.
- the other basic functions of the radio section 14255 are the same as those of the radio section 14155 on the master station side, and thus further description is omitted.
- Reference numeral 14256 denotes a transmission confirmation processing unit that receives the reception information 14206 and the transmission confirmation inquiry packet 14214 and outputs the transmission confirmation response packet 14210.
- the transmission confirmation processing unit 14256 Upon receiving the transmission confirmation inquiry packet 14214, the transmission confirmation processing unit 14256 checks the sequence number of the data packet 14202 that has not been stored by referring to the reception information 14206, and transmits that information to the transmission Output as acknowledgment packet 14210. For example, when the content of the transmission confirmation inquiry packet 14214 is "Did the sequence number reach from 100 to 200?", The content of the reception information 14206 is stored in the sequence number 50 If 191 and 193 are 199 ", the sequence number is 192 And 200 are omitted, and the transmission acknowledgment packet 14210 replies to that effect.
- the internal video / audio server 1430 outputs the high-definition video / audio stream 1411, and the master station communication device 1431 performs multicast distribution by the wireless signal 1416 compliant with the IEEE 802.11a.
- the slave stations 1402 to 1405 receive the radio signal 1416 at the internal slave station communication devices 1432 to 1435, respectively, and reproduce television and ivision images and sounds on the televisions 1442 to 1445, respectively.
- the transmission confirmation processing unit 14156 outputs a transmission confirmation inquiry packet 14114.
- radio section 14155 when activating beacon timing signal 14121, radio section 14155 outputs beacon 14300. Thereafter, at time 0 before time 1, the multicast distribution data packet 14112 received from the multicast distribution processing unit 14159 is output as the multicast 14301.
- the wireless unit 14155 outputs the transmission confirmation inquiry packet 14114 received from the transmission confirmation processing unit 14156 this time (time point 1) as a broadcast 14302.
- the radio section 14155 receives a power response from each of the slave station communication devices as a multicast retransmission request packet 14302 and outputs it as a transmission acknowledgment packet 14110. In this case, since no noise has occurred, there is no retransmission request for transmission failure.
- the processing of the multicast retransmission processing unit 14158 is started.
- the transmission failure has not occurred, and there is no transmission data packet 14102 to be retransmitted, so that the multicast retransmission data packet 14113 does not occur.
- the video / audio data packets which are the high-definition video / audio streams themselves, are sequentially stored in the buffer 14152, so that the untransmitted ones are output as the multicast distribution data packets 14112.
- reference numeral 14300 denotes the aforementioned beacon.
- 14310 is a component of the multicast distribution data packet 14112.
- 14320 is a transmission confirmation inquiry packet 14114 component, which is a multicast packet.
- 14321 is a transmission acknowledgment packet 14110 component, which is a unicast packet.
- the receiving side returns an ACK if the reception was successful without error, and the transmitting side returns an ACK if the ACK could not be received.
- both the radio transmission signal 14118 and the radio reception signal 14119 are used in a mixed state. Will be.
- the transmission confirmation inquiry packet component 14320 and the transmission confirmation response packet component 14321 are illustrated separately, but they may be inserted.
- the transmission confirmation inquiry packet component 14320 and the transmission confirmation response packet component 14321 are exchanged with the slave station communication device 1432
- the transmission confirmation inquiry packet component 14320 is communicated with the slave station communication device 1433. May be exchanged with the transmission acknowledgment packet component 14321.
- the multicast distribution is performed without any problem.
- the transmission confirmation processing unit 14156 outputs a transmission confirmation inquiry packet 14114.
- the radio section 14155 outputs a beacon 14300 when the beacon timing signal 14121 is activated. After that, the multicast distribution data packet 14112 received from the multicast distribution processing unit 14159 at the previous time (time 1) is output by the multicast method.
- the radio unit 14155 outputs the transmission confirmation inquiry packet 14114 received from the transmission confirmation processing unit 14156 this time (time point 2) in a broadcast format.
- the radio unit 14155 receives a power response from each of the slave station communication devices, and outputs it as a transmission confirmation response packet 14110. Since noise has occurred, transmission has failed, and a retransmission request has occurred. Although transmission failure occurs in the transmission confirmation itself, since it is a multicast, there is no problem because retransmission using ACK is performed.
- the processing of the broadcast retransmission processing unit 14157 is started. Since noise has occurred, transmission failure has occurred and there is a transmission data packet 14102 to be retransmitted, so that the unicast retransmission data packet 14115 is output. However, if a large amount of noise occurs, it takes time to exchange the transmission confirmation inquiry packet 14114 and the transmission confirmation response packet 14110, and the time left in the frame is exhausted, this processing does not occur. If time is left, the radio unit 14155 receives the multicast retransmission data packet 14115 and outputs it by a unicast method.
- the processing of the multicast retransmission processing section 14158 is started. Since noise has occurred, transmission failure has occurred, and the transmission data packet 14102 to be retransmitted exists, so that the multicast retransmission data packet 14113 is output. When a large amount of noise occurs and the number of the multicast retransmission data packets 14113 becomes large, the number of the multicast retransmission data packets 14113 is limited to such an extent that a transmission confirmation securing time can be secured in a frame.
- the process moves to the multicast distribution processing unit 14159. Since the video / audio data packets are sequentially stored in the buffer 14152, the untransmitted ones are output as the multicast distribution data packets 14112. However, there is a lot of noise However, when the number of the multicast retransmission data packets 14113 is large, the number of the multicast distribution data buckets 14112 is limited to such an extent that the transmission confirmation securing time can be secured in a frame. When the number of the multicast retransmission data packets 14113 is limited, the number of the multicast distribution data packets 14112 is suppressed to zero.
- the state of the radio signal 1416 at the time 2 is shown by (b) in FIG.
- the same components as those in (a) are given the same numbers.
- 14340 is noise.
- 14330 is the 14115 component of the multicast retransmission data packet.
- this 14330 is provided at time point 2, it can be seen that the transmission failure that occurred in the multicast distribution is recovered by the retransmission of the multicast.
- the re-casting retransmits each one of the slave station communication devices one by one, and is inefficient, so that the influence of noise has a large effect on the slave station communication devices. If given, Rikanokuryi does not immediately end.
- the slave station communication device that has failed in transmission retransmits from a small number of packets.
- the effect is achieved in conjunction with multicast retransmission, which retransmits packets starting from packets with a large number of slave communication devices that failed to transmit.
- this multicast retransmission which allows further retransmission by ACK, causes many transmission failures and ensures that the particular slave station communication device
- efficient retransmission is performed to multiple slave station communication devices at once, so efficient multicast By responding by retransmission, it is possible to efficiently and reliably address transmission failures.
- the transmission confirmation processing unit 14156 When the beacon timing signal 14121 becomes active, the transmission confirmation processing unit 14156 outputs a transmission confirmation inquiry packet 14114.
- the radio section 14155 outputs a beacon 14300 when the beacon timing signal 14121 is activated. Then, at the previous time (time 2), the multicast The multicast retransmission data packet 14113 received from the multicast retransmission processing unit 14158 and the multicast distribution data packet 14112 received from the multicast distribution processing unit 14159 are output by multicast.
- the radio section 14155 outputs the transmission confirmation inquiry packet 14114 received from the transmission confirmation processing section 14156 this time (time point 2) in the form of a broadcast.
- the radio unit 14155 receives the response from each of the slave station communication devices and outputs it as a transmission acknowledgment packet 14110. Since noise has occurred, transmission has failed, and a retransmission request has occurred. Since this transmission confirmation itself is a broadcast, retransmission using ACK is performed, and there is no problem.
- the process of the broadcast retransmission processing unit 14157 is started. Since the noise has occurred, the transmission has failed, and there is a transmission data packet 14102 to be retransmitted, so that the multicast retransmission data packet 14115 is output. However, when a large amount of noise occurs and the number of multicast retransmission data packets 14113 is large, this processing may not be executed for a long time in the frame. When the time is left, the radio unit 14155 receives the broadcast retransmission data packet 14115 and outputs it by a unicast.
- the processing of the multicast retransmission processing section 14158 is started. Since the noise has occurred, transmission failure has occurred, and the transmission data packet 14102 to be retransmitted exists, so that the multicast retransmission data packet 14113 is output. When a large amount of noise occurs and the number of the multicast retransmission data packets 14113 becomes large, the number of the multicast retransmission data packets 14113 is limited to such an extent that a transmission confirmation securing time can be secured in the frame. .
- the procedure moves to the processing of the multicast distribution processing unit 14159. Since new video / audio data packets are sequentially stored in the buffer 14152, those that have not been transmitted are output as the multicast distribution data packet 14112. However, when a large amount of noise occurs and the number of the multicast retransmission data packets 14113 increases, the number of the multicast distribution data packets 14112 is limited to such an extent that the transmission confirmation securing time can be secured in a frame. The multicast retransmission data packet 14113 If the number is limited, the number of the multicast distribution data packets 14112 is suppressed to zero.
- 14331 is a component of the multicast retransmission data packet 14113, which is a multicast signal.
- time 2 This is done for transmission failures that occurred before, in this example, transmission failures did not occur before time point 1, so transmission failures occurred at time point 2 It is a resend for something.
- the multicast distribution data packets 14112 of the amount observed at the point 1 are not originally transmitted. This is because the number of multicast retransmission data packets 14113 in the processing of the multicast distribution processing unit 14159 at the previous time point (time point 2) is large, so that the transmission confirmation securing time can be secured in the frame. This is because the number of distribution data packets 14112 has been limited. As a result, at this time point 3, the transmission confirmation inquiry packet 14114 and the transmission confirmation response packet 14110 are exchanged without any problem, instead of transmitting the multicast distribution data packet 14112 of the amount observed at the time point 1. The multicast retransmission at the next time point (time point 4) can be performed without any problem.
- the transmission confirmation processing unit 14156 outputs a transmission confirmation inquiry packet 14114.
- radio section 14155 when activating beacon timing signal 14121, radio section 14155 outputs beacon 14300. Then, at the previous time (time 3), the multicast retransmission data packet 14113 received from the multicast retransmission processing unit 14158 and the multicast distribution data packet 14112 received from the multicast distribution processing unit 14159 are output by multicast. I do. [0183] Next, radio section 14155 outputs a transmission confirmation inquiry packet 14114 received from transmission confirmation processing section 14156 this time (time point 4) as a broadcast.
- the radio section 14155 receives a reply from each of the slave station communication devices, and outputs it as a transmission confirmation response packet 14110. Although no noise has occurred, there are some cases where retransmission has been completed due to past transmission failure, and a retransmission request has been generated.
- the process of the broadcast retransmission processing unit 14157 is started. Although no noise has occurred, retransmission has not been completed due to transmission failure in the past, and there is a transmission data packet 14102 to be retransmitted, so that a multicast retransmission data packet 14115 is output. However, if the number of multicast retransmission data packets 113 is large, this process may not be executed for a long time remaining in the frame. If the time is left, the radio unit 14155 receives this retransmission data packet 14115 and outputs it in the form of a broadcast.
- the processing of the multicast retransmission processing unit 14158 is started. Although no noise has occurred, retransmission has not been completed due to past transmission failure, and there is a transmission data packet 14102 to be retransmitted, so that a multicast retransmission data packet 14113 is output. If the number of multicast retransmission data packets 14113 becomes large, the number of multicast retransmission data packets 14113 is limited to the extent that transmission confirmation securing time can be secured in the frame.
- the process moves to the multicast distribution processing unit 14159. Since the video and audio data packets are sequentially stored in the buffer 14152, those that have not been transmitted are output as multicast distribution data packets 14112. However, when the number of multicast retransmission data packets 14113 is large, the number of multicast distribution data packets 14112 is limited to such an extent that the transmission confirmation securing time can be secured in the frame.
- the amount of multicast distribution data packets 14112 observed at the time point 1 was not originally transmitted. This is because the number of multicast retransmission data packets 14113 in the processing of the multicast distribution processing unit 14159 at the previous time point (time point 3) is large, so that the transmission confirmation securing time can be secured in the frame. This is because the number of multicast distribution data packets 14112 was limited. As a result, at time 4, instead of transmitting the amount of multicast distribution data packets 141 12 seen at time 1, transmission confirmation inquiry packet 14114 and transmission confirmation response packet 14110 can be exchanged without any problem. The multicast retransmission at the next time (time 5) can be performed without any problem.
- the transmission confirmation processing unit 14156 When the beacon timing signal 14121 becomes active, the transmission confirmation processing unit 14156 outputs a transmission confirmation inquiry packet 14114.
- the radio section 14155 outputs a beacon 14300 when the beacon timing signal 14121 is activated. Thereafter, at the previous time (time point 4), the multicast retransmission data packet 14113 received from the multicast retransmission processing unit 14158 and the multicast distribution data bucket 14112 received from the multicast distribution processing unit 14159 are output by multicast. I do.
- the radio unit 14155 outputs, as a broadcast, the transmission confirmation inquiry packet 14114 received from the transmission confirmation processing unit 14156 this time (time 5).
- the radio section 14155 receives the power response from each of the slave station communication devices, and outputs it as a transmission confirmation response packet 14110. Although no noise has occurred, there is something that has been retransmitted due to past transmission failures, and a retransmission request has occurred!
- the process of the broadcast retransmission processing unit 14157 is started. Although no noise has occurred, retransmission has not been completed due to past transmission failures. Since the data packet 14102 exists, the broadcast retransmission data packet 14115 is output. Then, radio section 14155 receives this broadcast retransmission data packet 14115, and outputs the packet by unicast.
- the process moves to the multicast distribution processing unit 14159. Since the video and audio data packets are sequentially stored in the buffer 14152, the untransmitted ones are output as the multicast distribution data packet 14112.
- the multicast distribution data packet component 14310 is originally larger than the amount seen at point 1 because it should be sent before (point 4) and before (point 3). This is because the multicast distribution data packet 1411 that has been set is limited in order to secure the transmission confirmation securing time, and thus a large number of untransmitted multicast distribution data packets 1411 are left in the buffer 14152.
- the master station 1401 and the slave stations 1402 to 1405 are all installed in the home, but this is not essential.
- the present invention can be applied to a system that performs stream transmission, such as a lobby of a company, a waiting room of a station, desks of classrooms, learning meetings and seminar venues, a monitor for guidance of an exhibition hall, and a video transmission system in an airplane.
- a system that performs stream transmission such as a lobby of a company, a waiting room of a station, desks of classrooms, learning meetings and seminar venues, a monitor for guidance of an exhibition hall, and a video transmission system in an airplane.
- the video / audio server 1430 outputs the video / audio stream 11 and the ivision video / audio stream 11, but this is not essential.
- the transmission rate of the physical layer of IEEE802.11a is a maximum of 54 Mbps.
- one program that is, 1 Delivery to places is the limit. If this is applied to the technology of the present invention, a single program can be distributed to a plurality of locations. Of course, this configuration is also included in the scope of the present invention, but the present invention is not limited to this configuration.
- slave station communication devices 1432 to 1435 may distribute a plurality of programs and supply an arbitrary one program to a subordinate television.
- the stream transmission is not limited to video and audio.
- it may be silent video, music data, or interactive game data.
- IEEE 802.11a is widely used in the field, and there are many general-purpose IEEE 802.11a wireless modules.
- This embodiment can be realized by using a general-purpose IEEE802.11a wireless module as the wireless unit 14155 of the master station and the wireless unit 14255 of the slave station and adding an external configuration newly. With.
- the use of IEEE802.11a radio signals has such an effect, and this configuration is also included in the scope of the present invention.
- the present invention is not limited to this configuration.
- the present invention is effective even in a wired environment in an environment where noise is generated. In particular, it is more effective in harsh noise environments such as CATV and power line communication (light line communication or PLC). Therefore, the present invention is not limited to wireless.
- a beacon is placed at the beginning of a frame, but this is not essential. This conforms to the specifications of IEEE802.11a, and if other specifications are used, the specifications may be met. In the calculation of the transmission securing time, the time related to the beacon was ignored because it was sufficiently small, but may be taken into account as a matter of course. Other additional blocks within the frame may, of course, be taken into account.
- the power corresponding to transmission of a beacon followed by a multicast or a broadcast is used. If such a module is not used, the order is as follows. Need not be considered. For example, after the beacon 300, transmission may be performed in the order of broadcast and multicast.
- the one related to the multicast retransmission data packet and the one related to the multicast distribution data packet may be transmitted in this order.
- the frame period of the wireless signal compliant with the IEEE802.11a is set to 1 second, but this is not essential.
- the wireless transmission band can be spared. In that sense, it is better to increase the frame period. On the other hand, if the frame period is increased, it takes time to start the next multicast transmission, and the transmission delay increases. In that sense, it is better to reduce the frame period.
- the frame period may be shortened to shorten the exchange time, and after the initialization is completed, the frame period may be increased.
- the buffer adds the sequence number to the video / audio data packet and stores the packets sequentially. If the video / audio data packet originally has a unique number for each packet, if it is used as a sequence number, it is not necessary to add a new sequence number! / ,.
- the buffer stores the transmission information indicating to which slave station communication device the transmission failed, each time it is input. This is because the present embodiment uses the multicast retransmission and the multicast retransmission. New Instead of using two-cast retransmission, only multicast retransmission is used, and the transmission information may be information indicating whether or not the transmission failed. Then, multicast retransmission may be performed for all packets for which transmission has failed. Alternatively, only multicast retransmission is used without using multicast retransmission, and the transmission information may be the number of slave station communication devices that have failed transmission. Then, for a packet in which transmission has failed, multicast retransmission with a larger number of slave station communication devices in which transmission has failed may be performed.
- the radio unit on the master station side outputs a beacon timing signal, but this is not essential. This is because it is necessary to grasp the timing of the beacon outside the radio unit in order to secure the transmission confirmation time in the frame.
- beacon timing may be independently generated outside the radio unit, and may be occasionally exchanged with the radio unit for correction.
- the timing of the beacon may be independently generated outside the radio unit, completely in synchronization with the radio unit using a clock or the like.
- the approximate timing of the beacon may be independently generated and used outside the wireless unit from the timing of the transmission acknowledgment packet output by the wireless unit.
- the transmission confirmation processing unit may output a transmission confirmation inquiry packet addressed to each of the slave station communication devices when the beacon timing signal becomes active. However, this is not necessary.
- the transmission confirmation processing unit may output the transmission confirmation inquiry packet before the wireless unit outputs the transmission confirmation inquiry packet component as a wireless transmission signal.
- the beacon timing signal is transmitted before it becomes active, the beacon timing signal is transmitted in the frame immediately before the frame to be transmitted. Therefore, in this embodiment, the beacon timing signal is activated. When it becomes, it decided to send.
- the transmission confirmation processing unit outputs the child confirmation signal after the beacon timing signal becomes active and before the radio unit outputs the transmission confirmation inquiry packet component as a radio transmission signal.
- the station shall output a transmission confirmation inquiry packet addressed to each of the communication devices.
- the transmission confirmation processing unit activates the transmission information writing completion flag at the time when the processing regarding all the transmission confirmation response buckets is completed. That is, but it is not necessary.
- the exchange between the transmission acknowledgment inquiry packet and the transmission acknowledgment packet is a highly reliable one because it is retransmitted by ACK because of the broadcast, but the exchange may still fail.
- the maximum time may be determined in advance, and when the time has elapsed, the transmission information write completion flag may be set to active. As the maximum time, the transmission confirmation securing time may be used.
- the multicast retransmission is performed one retransmission for each slave station communication device, which is inefficient. Therefore, if the influence of the noise affects a large number of slave station communication devices, the recanoly does not end immediately. In this broadcast retransmission, it was decided that the slave station communication device that failed to transmit retransmitted packets from a small number. At the next point, the effect is achieved in conjunction with the multicast retransmission, in which retransmission is performed from the packet in which the local station communication device that failed to transmit is large.
- this retransmission of the broadcast which allows further retransmission by ACK, ensures that the number of transmission failures is high and that the certain slave station communication device is certain. It is not possible to perform further retransmission by ACK to other slave station communication devices, but it is possible to perform retransmission to multiple slave station communication devices at once. By coping with it, it is possible to efficiently and surely solve the transmission failure.
- the retransmission of the multicast is performed by retransmitting the packet from a small number of the slave station communication devices that have failed to transmit, and the multicast retransmission is that the number of the slave station communication devices that have failed the transmission is many.
- retransmission is performed from the packet, this need not be the case. Irrespective of the slave station communication device that failed to transmit, simply performing the multicast retransmission or the multicast retransmission from the old packet will slightly reduce the effect, but will still be effective. Also, among packets in which the number of slave station communication devices that failed to transmit is the same, With this configuration, the transmission can be completed before the buffer on the receiving side overflows.
- the packets are divided into several groups in the order of oldness, and the strength of the old group is also examined in the order of the number of slave units that failed to transmit in the group. It may be executed from the larger one. By doing so, When the number of slave communication devices that failed to be transmitted in the broadcast retransmission was small, the device was assigned to the device and retransmitted from the old one, so that it could be transmitted before the receiver overflows. Can be completed, and the effect can be obtained.
- the time required for transmitting one packet of the transmission data packet by the broadcast is set to 5 msec, but this is not essential.
- the time required for transmission of one transmission data packet by multicast is set to 1 msec, but this need not be the case.
- the multicast distribution processing unit does not need to start processing lmsec later.
- the processing is performed after the multicast retransmission processing section, so that the wireless section first creates a multicast retransmission data packet to be transmitted first, and then the multicast distribution to be transmitted by the wireless section.
- This is to allow the multicast distribution processing unit to create the data packet, and any other method may be used as long as it can be realized. For example, if the transmission information writing completion flag becomes active, the processing may be started 2 msec later, or 500 usec later.
- a configuration may be adopted in which the multicast retransmission processing unit notifies the end of the processing.
- the multicast distribution processing unit starts the process as soon as the transmission information writing completion flag becomes active, so that the multicast retransmission data packet and the multicast distribution data packet are created almost simultaneously,
- the unit may output the multicast retransmission data packet and the multicast distribution data packet in this order.
- FIG. 45 shows the internal configuration of the slave station communication device. An exception configuration may be used.
- Another configuration may be used as long as the transmission acknowledgment packet having the same content as the transmission acknowledgment packet is returned to the transmission acknowledgment inquiry packet having the same content as the transmission acknowledgment inquiry packet.
- the transmission information does not have to be configured to be generated only by the transmission confirmation processing unit.
- the multicast retransmission performed by the broadcast retransmission processing unit is a retransmission using ACK, it is a reliable retransmission. Therefore, regarding the retransmission performed by the multicast retransmission processing unit, it may be determined that the transmission failure has not succeeded, and the transmission information 106 may be created also by the multicast retransmission processing unit.
- the radio unit can receive the ACK directly and know whether or not the broadcast retransmission has succeeded, the radio unit creates the transmission information in the radio unit instead of the broadcast retransmission processing unit. Is also good.
- the transmission information does not have to be configured to be created by the multicast distribution processing unit.
- a configuration may be adopted in which, when a packet is read out from the buffer, information indicating that the packet has been transmitted is automatically added.
- the multicast distribution processing unit calculates the maximum time available for multicast distribution in a frame from the beacon timing signal, the transmission confirmation securing time, and the number of multicast retransmissions. Then, the upper limit of the number of multicast distribution was decided. From the number of multicast retransmissions, we calculated the approximate time required for multicast retransmission and determined the upper limit of the number of multicast distributions. But it doesn't have to be. Since the wireless unit actually performs multicast retransmissions wirelessly, it is possible to know the time when it was powerful. Therefore, the time of the radio unit may be notified directly.
- the transmission confirmation securing time is fixed, but need not be.
- the transmission confirmation processing unit includes a transmission confirmation securing time determination unit that determines a transmission confirmation securing time, and based on the result of the transmission confirmation, the frequency of transmission failure to a specific slave station communication device is high!
- the transmission confirmation securing time is set to be long, and otherwise, the transmission confirmation securing time is set to be small. In this way, if the frequency of transmission failures to a specific slave station communication device is high, the transmission confirmation securing time In the end, a large amount of time is left after the completion of transmission confirmation, and more reliable retransmission by ACK can be used, and more reliable broadcast retransmission can be used. There is an effect that retransmission can be reliably performed to the device. This configuration is also within the scope of the present invention.
- each of the plurality of slave station communication devices is individually inquired by broadcast as to whether or not the distribution was successful.
- This configuration has an effect that the most important transmission confirmation can be executed with a simple procedure.
- This configuration is also within the scope of the present invention. But it doesn't have to be.
- a query may be made to each of the plurality of slave station communication devices as to whether or not the distribution was successful by multicast.
- this method it is possible to make an inquiry at the same time by multicasting, and it is possible to make an inquiry in a short time. Therefore, there is an effect that the time required for transmission confirmation is reduced and the retransmission time can be increased.
- This configuration is also within the scope of the present invention.
- a multicast inquiry is made to each of a plurality of slave station communication devices as to whether or not the distribution has been successful, and a powerful slave station communication device that cannot receive a reply is re-transmitted.
- the inquiry may be made individually in the cast.
- inquiries can be made at the same time by multicast, and inquiries can be made in a short time. Therefore, there is an effect that the time required for transmission confirmation is reduced, and the retransmission time can be increased.
- retransmission by ACK cannot be performed in multicast, which is not reliable, transmission confirmation can be reliably performed by using multicast. This configuration is also within the scope of the present invention.
- Embodiment 2 the configuration described in Embodiment 2 is adopted, and when a plurality of slave station communication devices and a master station communication device transmit transmission confirmation packets and other normal packets by multicast. In addition, arbitration of transmission timing can be performed.
- the master station communication device has a configuration shown in FIG. 47, and integrates a multicast retransmission processing unit and a multicast distribution processing unit with the device of the previous embodiment shown in FIG. 41 to form a multicast distribution / retransmission processing unit. 14151 is different.
- the multicast distribution / retransmission processing unit 14151 refers to the transmission information 14107 from the buffer 14152, and specifies the sequence number 14103 of the video / audio data packet that has not been transmitted. It receives 14102, adds the multicast address, and outputs it to the radio unit 14155 as a multicast distribution / retransmission data packet. In addition, the multicast distribution / retransmission processing unit 14151 performs processing with the number of distribution / retransmissions corresponding to the time obtained by subtracting the transmission confirmation securing time from the frame period as the maximum number of retransmissions / retransmissions.
- the multicast communication device can treat multicast retransmission and new multicast distribution equally, and can simplify the circuit. This is a feature as compared with the previous embodiment.
- FIG. 47 and FIG. 41 it can be seen that the circuit is simpler in this embodiment. Although it has a small circuit scale, it has the following characteristics: its reliability can be improved in an environment in which burst errors occur.
- This embodiment is an example in which all the slave stations in the power group having the same basic configuration as the first embodiment can communicate not only with the same transmitting terminal but also with other transmitting terminals. It is.
- a system configuration assumed in the present embodiment will be described with reference to FIG. In FIG. 48, the same configuration as FIG. 2 uses the same name and the same number.
- 1 is an AV server
- 2 is a wired Ethernet HUB
- 3 is the first wireless transmitting terminal
- 4 is the second wireless transmitting terminal
- 5 is a wired Ethernet connecting 1
- 3 is the first wireless transmitting terminal
- 4 is the second wireless transmitting terminal
- 5 is a wired Ethernet connecting 1
- 3 is the first wireless transmitting terminal
- 4 is the second wireless transmitting terminal
- 5 is a wired Ethernet connecting 1
- 3 is the first wireless transmitting terminal
- 4 is the second wireless transmitting terminal
- 5 is a wired Ethernet connecting 1
- 4 is the second wireless transmitting terminal
- 5 is a wired Ethernet connecting 1
- 4 is
- the first wireless transmitting terminal 3, the first wireless receiving terminal 6, the second wireless receiving terminal 7, and the third wireless receiving terminal 7 have a parent-child relationship for performing wireless communication using IEEE802.il wireless LAN technology. It is in. That is, the first wireless transmitting terminal 3 is an AP (access point: master unit), and the first, second, and third wireless receiving terminals 6, 7, and 8 are STAs (stations: slave units). Similarly, the second wireless transmitting terminal 4 and the fourth wireless receiving terminal 9, the fifth wireless receiving terminal 10, and the sixth wireless receiving terminal 11 have a parent-child relationship for performing wireless communication using the IEEE 802.11 wireless LAN technology. It is in. That is, the second wireless transmission terminal 4 is an AP (access point: master unit), and the fourth, fifth, and sixth wireless reception terminals 9, 10, and 11 are STAs (stations: slave units).
- the first, second, third, and fourth wireless receiving terminals 6, 7, 8, and 9 form a first multicast group 12 for receiving the same multicast packet, and the fifth and sixth wireless receiving terminals
- the receiving terminals 10 and 11 form a second multicast group 13 that receives the same multicast packet. That is, in the first multicast group 12, there is a fourth wireless receiving terminal 9 which has no parent-child relationship with the first wireless transmitting terminal 3.
- the second wireless transmitting terminal 4 When viewed, the wireless receiving terminal belonging to the first multicast group 12 and the wireless receiving terminal belonging to the second multicast group coexist under the control of the own transmitting terminal. It will be.
- the data to be distributed to the first multicast group 12 and the data to be distributed to the second multicast group are not always the same, and the second transmitting terminal 4 transmits the first multicast group to the first multicast group as shown in FIG.
- the transmission buffer (a) and (b) for the multicast group 12 and the transmission buffer (c) and (d) for the second multicast group 13 are stored in the memory means 17.
- any one of the operations described in the first embodiment should be performed simultaneously for a plurality of operations.
- multicast packet of any of the above-described embodiments may be replaced with a broadcast packet.
- all or a part of the constituent elements of all the embodiments may be executed by a computer using a ROM and a program stored in the ROM.
- the wireless multicast technology empowering the present invention has a feature using the priority of a packet, and is useful for application to AV distribution or the like that requires multicast transmission with the highest priority. It can also be applied to applications such as data distribution.
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Abstract
Description
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CN2005800262075A CN1993933B (zh) | 2004-06-02 | 2005-06-01 | 无线传送方法 |
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JPWO2005119969A1 (ja) | 2008-04-03 |
EP1746773A1 (en) | 2007-01-24 |
US20080192661A1 (en) | 2008-08-14 |
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