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Efficient Error Control Using BlockAck and Network Coding for Multicast Transmission

This paper proposes a packet error control scheme for multicast transmission using BlockAck and network coding. The scheme reduces the number of retransmissions required and improves multicast error control in the 802.11 standard.

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Efficient Error Control Using BlockAck and Network Coding for Multicast Transmission

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  1. Efficient Error Control Using BlockAck and Network Coding for Multicast Transmission Date: 2009-1-20 Authors: Yonghwan Bang, et. al, Information and Communications Univ

  2. Abstract This contribution proposes a packet error control scheme for multicast transmission using BlockAck and network coding. Yonghwan Bang, et. al, Information and Communications Univ

  3. Outlines • Multicast error control requirement in 802.11 • Brief overview of network coding • Multicast BlockAck with network coding Yonghwan Bang, et. al, Information and Communications Univ

  4. Multicast error control requirement in 802.11 No error control mechanisms in the current standard. Current discussions at 802.11aa When a block of n packets are multicast to multiple stations, each packet error may cause each packet retransmission. In the best case, when a packet error happens at all receiving stations (error coincidence), only one retransmission can retrieve the error packet at all nodes. Statistically, error coincidence among many stations happens rarely in the low packet error rate limit. If m (= n×ε×r) errors are distributed to r receiving stations, then m retransmissions are required in the high packet error limit. … When multicast error rate is (ε× r), andless than1 with no error coincidence - Ave. # of retransmissions =n × ε × r When multicast error rate becomes 100% -Ave. # of retransmissions = n n packets ε … r Receivers multicast n = # of packets in a block ε= Packet error rate (unicast) r = # of receivers Yonghwan Bang, et. al, Information and Communications Univ

  5. Brief overview of network coding Exclusive OR bit operation Operator : Produces a value of true only in cases where the truth value of the operands differ. Logical axioms p1p2 = p2p1 (p1 p2) p3= p1( p2p3 ) =p1 p2p3 p1 p2p1 = p2 Error packet retrieval When packet pj is lost, the receiver coins x’ = p1 … pi pk …pn The transmitter sends NC error control frame obtained by x = p1 … pi pj pk …pn The receiver retrieves pj pj = x x’ Yonghwan Bang, et. al, Information and Communications Univ

  6. Brief overview of network coding Packet p1 Packet p1 Packet p2 Packet p2 Packet p3 … Packet(1...n, except j) Packet(12…n) Err Packet pj Packet p4 … … Packet pn Packet pn Packet pj Receiver Sender We can recover the Packeti by using XOR network coding Yonghwan Bang, et. al, Information and Communications Univ

  7. Multicast BlockAck with network coding -70- • Wireless multicast traffic error control Yonghwan Bang, et. al, Information and Communications Univ

  8. Multicast BlockAck with network coding -80- • Wireless multicast traffic error control A B C D Yonghwan Bang, et. al, Information and Communications Univ

  9. Multicast BlockAck with network coding -90- • Wireless multicast traffic error control A B C D Yonghwan Bang, et. al, Information and Communications Univ

  10. Multicast BlockAck with network coding -100- • Wireless multicast traffic error control B A D C A C D B A A B C D D B C Yonghwan Bang, et. al, Information and Communications Univ

  11. Multicast BlockAck with network coding REQ BlockAck Req -110- • Wireless multicast traffic error control B A D C A C D B A A B C D D B C Yonghwan Bang, et. al, Information and Communications Univ

  12. Multicast BlockAck with network coding REQ BlockAck Req -120- • Wireless multicast traffic error control B A D C A C D B A A B C D D B C Yonghwan Bang, et. al, Information and Communications Univ

  13. Multicast BlockAck with network coding -130- • Wireless multicast traffic error control B A D C A C D B Block Ack Block Ack A A B C D Block Ack D B C Yonghwan Bang, et. al, Information and Communications Univ

  14. Multicast BlockAck with network coding -140- • Wireless multicast traffic error control B A D C A C D B Block Ack Block Ack A Calculate the coding condition A B C D Block Ack D B C Yonghwan Bang, et. al, Information and Communications Univ

  15. Multicast BlockAck with network coding -150- • Wireless multicast traffic error control B A D C A C D B A A B C D A B C D D B C Yonghwan Bang, et. al, Information and Communications Univ

  16. Multicast BlockAck with network coding -160- • Wireless multicast traffic error control B A D C A C D B A A B C D A B C D A B C D A B C D D B C Yonghwan Bang, et. al, Information and Communications Univ

  17. Multicast BlockAck with network coding -170- • Wireless multicast traffic error control B A D B C A C D B C A A B C D A B C D A B C D A B C D D B C A Yonghwan Bang, et. al, Information and Communications Univ

  18. Multicast BlockAck with network coding -180- • Wireless multicast traffic error control B A D B C A C D B C <Ideal NC application> A A B C D A B C D A B C D A B C D D B C A # of transmitted data packet : 1024 # of receiver : 32 Yonghwan Bang, et. al, Information and Communications Univ

  19. Multicast BlockAck with network coding Simple implementation Yonghwan Bang, et. al, Information and Communications Univ

  20. Multicast BlockAck with network coding Well harmonized with existing BlockAck mechanism Our proposal adopts existing BlockAckReq and BlockAck frame without requiring any modification. The only difference is new type of data frame delivering error control information coined by XOR operation of several frames. Start seq BA control Block Ack Starting Sequence Control Block Ack Starting Sequence Control SA Duration/ID DA XOR Frame Body Block Ack Bitmap FCS Frame Control Frame Control Frame Control FCS FCS Duration/ID Duration/ID DA DA SA SA BA control Octets : 2 2 6 6 2 2 4 Existing BlockAckReq frame Octets : 2 2 6 6 2 2 128 4 Existing BlockAck frame Octets : 2 2 6 6 2 2 2 0-2312 4 BA control End seq Error control frame (proposed) • DA : Destination Address • SA : Source Address • FCS : Frame Check Sequence Yonghwan Bang, et. al, Information and Communications Univ

  21. Conclusion & Proposal Using network coding, at a packet error rate of 5%, network coding gain is approximately 30%. The higher the error rate, the higher the coding gain. Further study issues are anticipated : More than 1 error in a block per node. Non-uniform packet size. To consider network coding error control scheme in 802.11aa. To consider definition of BA control frame fields for network coding error control. Yonghwan Bang, et. al, Information and Communications Univ

  22. Thank You! Questions? Yonghwan Bang, et. al, Information and Communications Univ

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