2/25/2019May 2008 November 2007 doc.: IEEE 802.11-07/2752r1 January 2009 Efficient Error Control Using BlockAck and Network Coding for Multicast Transmission Date: 2009-01-19 Authors: Yonghwan Bang, et. al, Information and Communications Univ Peter Ecclesine, Cisco Systems

2/25/2019May 2008 November 2007 doc.: IEEE 802.11-07/2752r1 January 2009 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 Peter Ecclesine, Cisco Systems

Outlines Multicast error control requirement in 802.11 2/25/2019May 2008 November 2007 doc.: IEEE 802.11-07/2752r1 January 2009 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 Peter Ecclesine, Cisco Systems

Multicast error control requirement in 802.11 2/25/2019May 2008 January 2009 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), and less than 1 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 멀티캐스트에서의 error correction을 위한 retransmission을 하게 되면 bandwidth 낭비가 심하다 최악의 경우 유니캐스트와 같아 진다. multicast n = # of packets in a block ε = Packet error rate (unicast) r = # of receivers Yonghwan Bang, et. al, Information and Communications Univ

Brief overview of network coding 2/25/2019May 2008 doc.: IEEE 802.11-08/0529r0 January 2009 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 p1 p2 = p2 p1 (p1 p2) p3= p1 ( p2 p3 ) = p1 p2 p3 p1 p2 p1 = 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’ XOR is both an associative and a commutative operation. Yonghwan Bang, et. al, Information and Communications Univ Peter Ecclesine, Cisco Systems

Brief overview of network coding 2/25/2019May 2008 doc.: IEEE 802.11-08/0529r0 January 2009 Brief overview of network coding Packet p1 Packet p1 Packet p2 Packet p2 Packet p3 … Packet(1 2 … n) Packet(1 ... n, except j) 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 Peter Ecclesine, Cisco Systems

Multicast BlockAck with network coding -70- January 2009 Multicast BlockAck with network coding Wireless multicast traffic error control Yonghwan Bang, et. al, Information and Communications Univ

Multicast BlockAck with network coding -80- January 2009 Multicast BlockAck with network coding Wireless multicast traffic error control A B C D Yonghwan Bang, et. al, Information and Communications Univ

Multicast BlockAck with network coding -90- January 2009 Multicast BlockAck with network coding Wireless multicast traffic error control A B C D Yonghwan Bang, et. al, Information and Communications Univ

Multicast BlockAck with network coding -100- January 2009 Multicast BlockAck with network coding Wireless multicast traffic error control D A C B A D C B A B C D B C A D Yonghwan Bang, et. al, Information and Communications Univ

Multicast BlockAck with network coding -110- January 2009 Multicast BlockAck with network coding Wireless multicast traffic error control D A C B A D C B A B C D REQ BlockAck Req B C A D Yonghwan Bang, et. al, Information and Communications Univ

Multicast BlockAck with network coding -120- January 2009 Multicast BlockAck with network coding Wireless multicast traffic error control D A C B A D C B A B C D REQ BlockAck Req B C A D Yonghwan Bang, et. al, Information and Communications Univ

Multicast BlockAck with network coding -130- January 2009 Multicast BlockAck with network coding Wireless multicast traffic error control D A C B A D C B Block Ack Block Ack A B C D Block Ack B C A D Yonghwan Bang, et. al, Information and Communications Univ

Multicast BlockAck with network coding -140- January 2009 Multicast BlockAck with network coding Wireless multicast traffic error control D A C B A D C B Block Ack Block Ack Calculate the coding condition A B C D Block Ack B C A D Yonghwan Bang, et. al, Information and Communications Univ

Multicast BlockAck with network coding -150- January 2009 Multicast BlockAck with network coding Wireless multicast traffic error control D A C B A D C B A B C D A B C D B C A D Yonghwan Bang, et. al, Information and Communications Univ

Multicast BlockAck with network coding -160- January 2009 Multicast BlockAck with network coding Wireless multicast traffic error control D A C B A D C B A B C D A B C D B C A D Yonghwan Bang, et. al, Information and Communications Univ

Multicast BlockAck with network coding -170- January 2009 Multicast BlockAck with network coding Wireless multicast traffic error control D A B C C A D C B B A B C D A B C D A B C A D Yonghwan Bang, et. al, Information and Communications Univ

Multicast BlockAck with network coding -180- January 2009 Multicast BlockAck with network coding Wireless multicast traffic error control D A B C C A D C B B A B C D <Ideal NC application> A B C D A B C A D # of transmitted data packet : 1024 # of receiver : 32 Yonghwan Bang, et. al, Information and Communications Univ

Multicast BlockAck with network coding 2/25/2019May 2008 doc.: IEEE 802.11-08/0529r0 January 2009 Multicast BlockAck with network coding Simple implementation Transmit a block of multicast frames Gather packet loss information from receivers Find coding condition Transmit error control frame coined by XOR operation of several frames Yonghwan Bang, et. al, Information and Communications Univ Peter Ecclesine, Cisco Systems

Multicast BlockAck with network coding 2/25/2019May 2008 doc.: IEEE 802.11-08/0529r0 January 2009 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. Octets : 2 2 6 6 2 2 4 Frame Control Duration/ID DA SA FCS BA control Block Ack Starting Sequence Control Existing BlockAckReq frame Octets : 2 2 6 6 2 2 128 4 Frame Control Duration/ID DA SA FCS Block Ack Bitmap BA control Block Ack Starting Sequence Control Existing BlockAck frame Octets : 2 2 6 6 2 2 2 0-23124 4 Frame Control Duration/ID DA SA FCS XOR Frame Body Start seq 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 Peter Ecclesine, Cisco Systems

2/25/2019May 2008 doc.: IEEE 802.11-08/0529r0 January 2009 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 Peter Ecclesine, Cisco Systems

Thank You! Questions? January 2009 2/25/2019May 2008 doc.: IEEE 802.11-08/0529r0 January 2009 Thank You! Questions? Yonghwan Bang, et. al, Information and Communications Univ Peter Ecclesine, Cisco Systems