doc.: IEEE g Submission July 14, 2009 René Struik (Certicom Research)Slide 1 Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [PHY Header Discussion] Date Submitted: [July 14, 2009] Source: [René Struik] Company [Certicom Research] Address [5520 Explorer Drive, Fourth Floor, Mississauga, ON, L4W 5L1, Canada] Voice: [+1 (905) ], FAX: [+1 (905) ], Re: [ ] Abstract:[This document discusses how to add PHY header error correction capabilities with low implementation cost and without data expansion. This presentation uses formats, due to pending merging process nan.] Purpose:[Improve energy efficiency and early error detection with g PHYs.] Notice:This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release:The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P

doc.: IEEE g Submission July 14, 2009 René Struik (Certicom Research)Slide 2 IEEE g PHY Header Discussion René Struik (Certicom Research)

doc.: IEEE g Submission July 14, 2009 René Struik (Certicom Research)Slide 3 PHY Header Considerations (1) PHY (2.4 GHz) Modulation scheme (2.4 GHz) – Bit-to-symbol mapping:4 bits  symbol (16-ary value) – Symbol-to-chip mapping: symbol  32-bit codeword (chipping sequence) MAC Source: , §6.3, Fig. 16, p. 43 Source: , §6.3.2, Fig. 17, p. 44  127 octets Source: , § and § , p. 47

doc.: IEEE g Submission July 14, 2009 René Struik (Certicom Research)Slide 4 PHY Header Considerations (2) PHY (2.4 GHz) Modulation scheme (2.4 GHz) – Bit-to-symbol mapping:4 bits  symbol (16-ary value) – Symbol-to-chip mapping: symbol  32-bit codeword (chipping sequence) MAC Source: , §6.3, Fig. 16, p. 43 Source: , §6.3.2, Fig. 17, p. 44  127 octets Source: , § and § , p. 47 Channel coding: – intra-symbol demodulation – MAC error detection – no PHY header error control

doc.: IEEE g Submission July 14, 2009 René Struik (Certicom Research)Slide 5 PHY Header Considerations (3) Idealized PHY (2.4 GHz) Modulation scheme (2.4 GHz) – Bit-to-symbol mapping:4 bits  symbol (16-ary value) – Symbol-to-chip mapping: symbol  32-bit codeword (chipping sequence) Assumptions – Actual octet pattern of the 4-octet PHY preamble does not matter for synchronization: The chipping sequence takes care of that; – The "comma" octet pattern is fixed, to indicate where the preamble stops; – The "length of MPDU" field is not part of the synchronization process. Source: , §6.3, Fig. 16, p. 43  127 octets Channel coding: – intra-symbol demodulation – MAC error detection – no PHY header error control

doc.: IEEE g Submission July 14, 2009 René Struik (Certicom Research)Slide 6 PHY Header Considerations (4) Idealized PHY (2.4 GHz) Modulation scheme (2.4 GHz) – Bit-to-symbol mapping:4 bits  symbol (16-ary value) – Symbol-to-chip mapping: symbol  32-bit codeword (chipping sequence) Assumptions – Actual octet pattern of the 4-octet PHY preamble does not matter for synchronization: The chipping sequence takes care of that; – The "comma" octet pattern is fixed, to indicate where the preamble stops; – The "length of MPDU" field is not part of the synchronization process. Result – Error correcting code on PHY header without data expansion – Low-cost implementation, to degree implementer wants Source: , §6.3, Fig. 16, p. 43  127 octets Channel coding: – intra-symbol demodulation – MAC error detection – no PHY header error control Channel coding: – intra-symbol demodulation – MAC error detection – PHY header error correction

doc.: IEEE g Submission July 14, 2009 René Struik (Certicom Research)Slide 7 PHY Header Considerations (5) Idealized PHY (2.4 GHz) Details – Code with symbols from Galois field GF(16), i.e., 16-ary symbols – : [2,2,1] 16-ary code preceded by 10 fixed symbols 4-octet = 8 symbol all-zero synch sequence 1-octet = 2-symbol fixed SFD sequence (“comma”) 1-octet = 2-symbol variable length field Alternative view: coset of [12,2,1] code – with error correction: [12,2,11] MDS code over GF(16) 4-octet = 8-symbol redundancy information (parity-checks) 1-octet = 2-symbol redundancy information (more parity-checks) 1-octet = 2-symbol information set (length info) Source: , §6.3, Fig. 16, p. 43  127 octets Channel coding: – intra-symbol demodulation – MAC error detection – PHY header error control

doc.: IEEE g Submission July 14, 2009 René Struik (Certicom Research)Slide 8 PHY Header Considerations (6) Idealized PHY (2.4 GHz) Details – Code with symbols from Galois field GF(16), i.e., 16-ary symbols – with error correction: [12,2,11] MDS code over GF(16) 4-octet = 8-symbol redundancy information (parity-checks) 1-octet = 2-symbol redundancy information (more parity-checks) 1-octet = 2-symbol information set (length info) Implementation considerations: – Erasure decoding. If one does not see part of preamble, simply decode punctured code Example #1: [12,2,11]  [4,2,3] (throw away 4-octet preamble) Example #2: [12,2,11]  [2,2,1] (only read information set, i.e., length info) – Flexible implementation. Trade-off decoding logic and error control capabilities Example: if one does not wish to implement encoding, simply ignore redundancy bits – More coding gain possible. Combine demodulation and MDS error control (ML, soft-decision, etc.) Source: , §6.3, Fig. 16, p. 43  127 octets Channel coding: – intra-symbol demodulation – MAC error detection – PHY header error control