Submission Title: [FEC & Modulation Options and considerations] Sept 2005 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [FEC & Modulation Options and considerations] Date Submitted: [5 Oct 2005] Source: [Francois Chin, Sam Kwok, Sai-Ho Wong] Company: [Institute for Infocomm Research, Singapore] Address: [21 Heng Mui Keng Terrace, Singapore 119613] Voice: [65-68745687] E-Mail: [chinfrancois@i2r.a-star.edu.sg] Abstract: [] Purpose: [Assist the group in the selection of a modulation scheme] 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. Francois Chin (I2R)

Outline Baseline What we propose : FEC 7 Modulation to go with FEC 7: Sept 2005 Outline Baseline What we propose : FEC 7 Modulation to go with FEC 7: 8-PPM + BPSK Complexity scalability consideration Francois Chin (I2R)

Baseline - Modulation(from 582r0) Sept 2005 Baseline - Modulation(from 582r0) Francois Chin (I2R)

Systematic Convolutional Encoder Sept 2005 FEC Options (from 602r0) SOC code K= 3,4 or 5 R = 1/4 Coherent Receiver: True Rate = ¼ Non Coherent Receiver: Equivalent to Rate = ½ (Rate ¼ with erasures) FEC 1 Convolutional Encoder K= 3,4 or 5 R= 1/4 Coherent Receiver: True Rate = ¼ Non Coherent Receiver: Equivalent to Rate = ½ (Rate ¼ with erasures) FEC 2 Systematic Convolutional Encoder K= 3,4 or 5 R = 1/2 Convolutional Encoder K=3, R= 1/2 FEC 3 Coherent Receiver: Concatenated code, Rate = ¼ Non Coherent Receiver: Convolutional code, Rate = ½ Systematic Convolutional Encoder K= 3,4 or 5 R = 1/2 BCH or RS GF(28): RS(40,32) GF(26): RS(53,43) Coherent Receiver: Concatenated code Rate = 0.4 Non Coherent Receiver: RS code, Rate = 0.8 FEC 4 Systematic Convolutional Encoder K= 3,4 or 5 R= 1/2 FEC 5 Coherent Receiver: Convolutional code Rate = ½ Non Coherent Receiver: Uncoded Convolutional Encoder K= 3,4 or 5 R= 1/3 FEC 6 Coherent Receiver: Convolutional code Rate = 1/3 Non Coherent Receiver: Convolutional code Rate = 1/2 Coherent Receiver: True Rate = ½ Non Coherent Receiver: Equivalent to Rate = 2/3 (Rate ½ with puncturing) Systematic Convolutional Encoder K= 3,4 or 5 R= 1/2 FEC 7 Francois Chin (I2R)

Summary of rates (modified from 602r0) Sept 2005 Summary of rates (modified from 602r0) Same ave PRF as the preamble section Francois Chin (I2R)

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> Sept 2005 FEC 6: Burst Pulses S = ++--+-+----+++- = S 1 chip ~ 2 ns burst duration = TB = 15 chips ~ 30 ns symbol duration ~ 1.0us = 480 chips = 32 TB Proposed peak PRF of 494 MHz, with S code of length 15 S code duration = 15 / peak PRF ~ 30 ns Another candidate, S = -+++----+-+--++ (any 15-chip M-seq) Chip duration is 1/peak PRF Francois Chin (I2R) <author>, <company>

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> Sept 2005 Proposal 6 : 4-PPM + BPSK Guard time for channel delay spread (120ns) C NC 000 00 - 001 010 01 - 011 110 11 - 111 100 10 - 101 S -S 15 16 31 3 8 19 20 4 7 12 11 23 24 27 28 Francois Chin (I2R) <author>, <company>

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> Sept 2005 FEC 7: Codec & Modem s1 s2 8-PPM demod Common Coder + Modulation Mapping Viterbi ½ rate r1 r2 Systematic Bit s1 s2 8-PPM + BPSK modulatorwith input [s1 s2 r1 r2] Non Coherent Receiver Info. Bit Convolutional 1/2 a1 a2 s1 s2 Redundant Bit 8-PPM + BPSK demod Viterbi ½ rate r1 r2 r1 r2 Coherent Receiver Francois Chin (I2R) <author>, <company>

Modulation : 8-PPM + BPSK Guard time (120 ns) Sept 2005 Scrambling Range (120 ns) Coh S1s2r1r2 N- Coh s1s2r1 - 0000 000- 0001 0010 001- 0011 0110 011- 0111 0100 010- 0101 1100 110- 1101 1110 111- 1111 1010 101- 1011 1000 100- 1001 Modulation : 8-PPM + BPSK 1 3 2 5 4 7 6 9 8 11 10 13 12 15 14 17 16 19 18 21 20 23 22 25 24 27 26 29 28 31 30 S -S Gray coded Francois Chin (I2R)

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> Sept 2005 FEC 7: Burst Pulses 1 chip ~ 2 ns burst duration = TB = 31 chips ~ 63 ns symbol duration ~ 2.0us = 992 chips = 32 TB Proposed peak PRF of 494 MHz, with S code of length 31 S code duration = 31 / peak PRF ~ 63 ns S can be binary version of the BPTS (meant for preambles) Via Ternary to Binary: +/- → 1; 0 → -1 Chip duration is 1/peak PRF Francois Chin (I2R) <author>, <company>

So what we propose in FEC 7 is: Sept 2005 So what we propose in FEC 7 is: Coherent Non-Coherent Tx (Common for Coherent and Non Coherent) Symbol Time ~2µs Rb @ PHY-SAP ~1 Mbps FEC 7 Convolutional 1/2 Modulation 8-PPM + Polarity (4 bits per symbol) Channel Raw Rate 2 Mbps Rx Demodulation 8PPM + Polarity (4 bits/symbol) 8PPM only (3 bits/symbol) Decoder Viterbi 1/2 ~1Mbps  Perfect compatibility between Tx and coherent and non-coherent Rx Francois Chin (I2R)

Features of FEC 7 Options 7: Longer burst S Sept 2005 Features of FEC 7 Options 7: Longer burst S better inter pulse interference suppression for coherent receiver Can have specific burst sequence for different piconet, thus further SOP interference suppression with set of nearly orthogonal sequences for the burst Large burst energy gives better SNR in non-coherent receiver 8-PPM > 4-PPM demod > 2-PPM, the former has better uncoded BER performance Base rate of codec is ½ Lower codec complexity to meet low cost / power requirement Francois Chin (I2R)

Piconet-Specific Burst Sequences Sept 2005 Piconet-Specific Burst Sequences PBTS for Preambles S1 +0++000-+-++00++0+00-0000-0+0-- S2 +-0+0+00+000+0++---0-+00-++0000 S3 0+-+000+0-0++0-0000+-00-00-++++ S4 0+0000-00-0+-00+++-+000-+0+++0- S5 -++0-+---00+00++0000+0+-0+0+000 S6 0++-++0+000+00-0-0++0000--+00-+ Burst Sequences S1 +-++---+++++--++-+--+----+-+-++ S2 ++-+-+--+---+-+++++-++--+++---- S3 -+++---+-+-++-+----++--+--+++++ S4 -+----+--+-++--+++++---++-+++-+ S5 +++-+++++--+--++----+-++-+-+--- S6 -+++++-+---+--+-+-++----+++--++ Burst Sequence can be derived from Preamble sequences Via Ternary to Binary: +/- → 1; 0 → -1 Francois Chin (I2R)

RX Complexity Scalability Sept 2005 RX Complexity Scalability All options allow signal detection in low-cost low-power implementation without viterbi decoder, especially in Non-coherent receiver For such non-coherent RX, FEC 1~4 with 2PPM+BPSK requires 2PPM demod on every alternate ~0.5us symbol to detect systematic bit, 3dB loss of energy as other burst (or symbol) carrying redundant bit is not used for detection FEC 5 with 2PPM+BPSK requires 2PPM demod on every symbol to detect systematic bit Francois Chin (I2R)

RX Complexity Scalability <month year> doc.: IEEE 802.15-<doc#> Sept 2005 RX Complexity Scalability FEC 6 with 4PPM+BPSK requires 2PPM demod on every ~1us symbol to detect 1 systematic bit ~1us S -S 31 32 63 7 16 39 40 8 15 24 23 47 48 56 57 detect information bit ‘0’ detect information bit ‘1’ Francois Chin (I2R) <author>, <company>

RX Complexity Scalability <month year> doc.: IEEE 802.15-<doc#> Sept 2005 RX Complexity Scalability FEC 7 with 8PPM+BPSK requires 4PPM demod on every ~2us symbol to detect 2 systematic bit ~2us 1 3 2 5 4 7 6 9 8 11 10 13 12 15 14 17 16 19 18 21 20 23 22 25 24 27 26 29 28 31 30 S -S detect ‘00’ detect ‘01’ detect ‘11’ detect ‘10’ Francois Chin (I2R) <author>, <company>

RX Complexity Scalability Sept 2005 RX Complexity Scalability given low-cost low-power receiver implementation (uncoded bit detection only, either without or turning off, viterbi decoder) is an attractive feature, 2PPM+BPSK modulation option is not energy efficient, as only alternate burst (or symbol) of energy is used for detection Using same energy integration / capture interval for uncoded bit detection in non-coherent rxr, 8PPM + BPSK option using 4PPM demod (on every ~2us symbol to detect 2 systematic bit) will capture less noise than 4PPM + BPSK option using 2PPM demod (on every ~1us symbol to detect 1 systematic bit) Francois Chin (I2R)

Statistics of Collected Burst Energy Sept 2005 Statistics of Collected Burst Energy Let’s look at the signal+noise and noise-only statistics for 2-, 4- and 8-PPM, with symbol period of 0.5us, 1us and 2us respectively and 8, 16 & 32 pulses / symbols, respectively. Francois Chin (I2R)

Statistics of Collected Burst Energy Sept 2005 Statistics of Collected Burst Energy 2-PPM case symbol period = 0.5us 8 pulses / symbol Pulse SNR = 0dB Noise-only slot Mean = 8 Std-Dev = √8 Signal+Noise slot Mean = 16 Std-Dev = √16*√3 Francois Chin (I2R)

Statistics of Collected Burst Energy Sept 2005 Statistics of Collected Burst Energy 4-PPM case symbol period = 1us 16 pulses / symbol Pulse SNR = 0dB Noise-only slot Mean = 16 Std-Dev = √16 Signal+Noise slot Mean = 32 Std-Dev = √32*√3 Francois Chin (I2R)

Statistics of Collected Burst Energy Sept 2005 Statistics of Collected Burst Energy 8-PPM case symbol period = 2us 32 pulses / symbol Pulse SNR = 0dB Noise-only slot Mean = 32 Std-Dev = √32 Signal+Noise slot Mean = 64 Std-Dev = √64*√3 Francois Chin (I2R)

Statistics of Collected Burst Energy Sept 2005 Statistics of Collected Burst Energy Generally, for N pulses / symbol with Pulse SNR =  Noise-only slot Mean = N, Std-Dev = √N Signal+Noise slot Mean = ( +1)N, Std-Dev = √((2 +1)N) For more pulses/symbols, Std-Dev / Mean decreases, means the statistics are more confined to the mean value Francois Chin (I2R)

Symbol Error Performance Sept 2005 Symbol Error Performance Depends on the extense of overlaps of the Noise-only and signal+noise p.d.f. curves More overlaps means there is higher probability that the noise-only slot to exceed the signal+noise slot, therefore, higher SER Less overlaps for higher order PPM means lower SER Francois Chin (I2R)

PPM Demod BER (Non-Coherent in AWGN) Sept 2005 PPM Demod BER (Non-Coherent in AWGN) 2- & 4- PPM receivers Will further be passed into rate ½ Viterbi decoder 8-PPM receivers De-punctured and further passed into rate ½ Viterbi decoder Francois Chin (I2R)

Sept 2005 AWGN Uncoded BER at PPM Demod output (Non-Coherent w/o Viterbi Decoder) Francois Chin (I2R)