Submission Title: [FEC Options summary for TG4a ] Oct 2005 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [FEC Options summary for TG4a ] Date Submitted: [30-Sep-2005] Source: [Michael Mc Laughlin] Company [Decawave Ltd.] Address [25 Meadowfield, Sandyford, Dublin 18, Ireland] Voice:[+353−1−2954937 ], FAX: [What’s a FAX?], E−Mail: [michael@decawave.com] Re: [802.15.4a.] Abstract: [Summarises the current FEC proposals for TG4a forward error correction] Purpose: [To promote discussion in 802.15.4a.] Notice: This document has been prepared to assist the IEEE P802.15. 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 P802.15. Mc Laughlin, Decawave

FEC Options 2-4 FEC 2 FEC 3 FEC 4 Oct 2005 Systematic Convolutional Encoder K= 4 R= 1/4 FEC 2 Coherent Receiver: True Rate = ¼ K=4 Non Coherent Receiver: Rate ½ K=3 Systematic Convolutional Encoder K= 3 R = 1/2 Convolutional Encoder K=3, R= 1/2 FEC 3 Coherent Receiver: Concatenated code, Rate = ¼ K=5 Non Coherent Receiver: Convolutional code, Rate = ½ K=3 Systematic Convolutional Encoder K= 3 R = 1/2 Reed Solomon GF(26): RS(55, 63) Coherent Receiver: Concatenated code Rate = 0.4 Non Coherent Receiver: RS code, Rate = 0.8 FEC 4 Mc Laughlin, Decawave

FEC vs Symbol rate FEC Options have different code rates Oct 2005 FEC vs Symbol rate FEC Options have different code rates Implies different Bit Rates, Symbol Rates and PRFs Mc Laughlin, Decawave

FEC option 4 is simulated like this Oct 2005 FEC option 4 is simulated like this ~900ns 1 symbol every 0.9µs. RS (63,55) => Data rate is 1Mbit/s 14 pulses/code => 1.1M sym/sec and average PRF ~ 16MHz Mc Laughlin, Decawave

Rate ¼ (FEC 1, FEC 2 and FEC 3) all need 4 bits / uncoded bit Oct 2005 Rate ¼ (FEC 1, FEC 2 and FEC 3) all need 4 bits / uncoded bit ~1000ns 2 symbols transmitted every microsecond for 1Mbit/sec => 2M sym/sec and average PRF ~ 16MHz Mc Laughlin, Decawave

Summary of rates simulated Oct 2005 Summary of rates simulated Mc Laughlin, Decawave

Oct 2005 CM1 Coherent PER Mc Laughlin, Decawave

Oct 2005 CM8 Coherent PER Mc Laughlin, Decawave

Oct 2005 Summary FEC option 4 coherent performance was best of the three (by about ½ dB) FEC option 2 was next (about ½ dB better than Option 3) Complexity/Simpicity is another issue as is non-coherent performance expect similar PER for 3 options Mc Laughlin, Decawave