1. Submission Title: [FEC Options summary for TG4a ]
Oct 2005
Project: IEEE P 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− ], FAX: [What’s a FAX?], E−Mail:
Re: [ a.]
Abstract: [Summarises the current FEC proposals for TG4a forward error correction]
Purpose: [To promote discussion in a.]
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
Mc Laughlin, Decawave

2. 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

3. 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

4. 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

5. 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

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

7. Oct 2005
CM1 Coherent PER
Mc Laughlin, Decawave

8. Oct 2005
CM8 Coherent PER
Mc Laughlin, Decawave

9. 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