2/4/2019May 2008 November 2007 doc.: IEEE 802.11-07/2752r1 Efficient Error Control Using Network Coding for Multicast Transmission Date: 2009-03-19 Authors: J.-K. Kevin Rhee, et. al, KAIST Peter Ecclesine, Cisco Systems

Contents Overview of Network Coding Issues for Network Coding 2/4/2019May 2008 doc.: IEEE 802.11-08/0529r0 Contents Overview of Network Coding Issues for Network Coding Our Proposal System Block Diagram Example of Network Coding Error Control Frame Conclusion J.-K. Kevin Rhee, et. al, KAIST Peter Ecclesine, Cisco Systems

Overview of Network Coding 2/4/2019May 2008 doc.: IEEE 802.11-08/0529r0 Overview of Network Coding Problems of existing error control scheme in 802.11 It involves error control frame storming. Multicast Error Rate (# of Receiving station X Unicast error rate) MER = 1, if # of Receiving station X Unicast error rate > 1 MER = # of Receiving station X Unicast error rate If MER = 1, it required more than 100% of overhead. How network coding benefits to multicast error control Network coding requires 3 times less overhead comparing with the existing error control scheme. J.-K. Kevin Rhee, et. al, KAIST Peter Ecclesine, Cisco Systems

Issues for Network Coding 2/4/2019May 2008 doc.: IEEE 802.11-08/0529r0 Issues for Network Coding Handling variable length of frames The size of error control frames coined by XOR operations are same as the largest frames among a set. The way notifying receiving nodes of actual payload size of a missing frame is required. XOR payload design concept We should clarify which information should be XORed and which information should not. J.-K. Kevin Rhee, et. al, KAIST Peter Ecclesine, Cisco Systems

Our Proposal = Handling variable length of frames -50- Our Proposal Handling variable length of frames Padding a special ending bit sequence at the end of payload. • Actual data payload is retrieved by matching ending bit sequence. Payload EoS Frame 1 Frame 2 Payload EoS Padding(0x0000….) Frame 3 Payload EoS Padding(0x0000….) = XORed Payload Error control frame J.-K. Kevin Rhee, et. al, KAIST

Our Proposal = Handling variable length of frames Retrieve -60- XORed Payload Error control frame Payload EoS Frame 1 Frame 3 Payload EoS Padding(0x0000….) = Retrieved frame Payload EoS Padding(0x0000….) Payload of Frame 2 J.-K. Kevin Rhee, et. al, KAIST

Our Proposal = Handling variable length of frames -70- Our Proposal Handling variable length of frames Introducing a length field XORing. • Actual data payload is retrieved by matching ending bit sequence. • This scheme does not require Length Payload Frame 1 Frame 2 Length Payload Padding(0x0000….) Frame 3 Length Payload Padding(0x0000….) = XORed Length XORed Payload Error control frame J.-K. Kevin Rhee, et. al, KAIST

Our Proposal = Handling variable length of frames Retrieve -80- XORed XORed Payload Error control frame Length Payload Frame 1 Frame 3 Length Payload Padding(0x0000….) = Length Payload Padding(0x0000….) Retrieved frame Payload of Frame 2 J.-K. Kevin Rhee, et. al, KAIST

System Block Diagram System Blocks -90- J.-K. Kevin Rhee, et. al, KAIST

Example of Network Coding Error Control Frame -100- Example of Network Coding Error Control Frame Block ACK Network Coding Error Control Frame. It takes Block ACK Control Path. In BAR Control field, we define an additional type field distinguishing error control frames from others. Start Seq and End Seq fields notify receiving stations of encoded frames. Maximum size of XOR frame body is 2425 (2423 bytes-Data + 2 bytes-Length Filed or EoS) Frame control Duration/ ID DA SA BAR Control Start Seq End Seq XOR Frame Body FCS Type (4bits) 0x1 Reserved (8bits) TID (4bits) XORed Length (2octets) XORed Frame Body (2423octets) XORed Frame Body (0-2423octets) Ending Sequence / Padding J.-K. Kevin Rhee, et. al, KAIST

-110- Conclusion We propose two ways of supporting variable length of frames for network coding. Introducing a Length Field Padding EoS bit sequence at the end of payload. Both scheme can allow receiving stations to retrieve actual data payload out of XORed payload. We also proposed system block diagram for network coding multicast error control and example format of error control frame compliant with Block ACK. J.-K. Kevin Rhee, et. al, KAIST

Thank You! 2/4/2019May 2008 doc.: IEEE 802.11-08/0529r0 J.-K. Kevin Rhee, et. al, KAIST Peter Ecclesine, Cisco Systems