1. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Sept 2004
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Proposed Code Sequences for IEEE a Alt-PHY]
Date Submitted: [13 Sept, 2004]
Source: [Francois Chin, Sam Kwok, Xiaoming Peng, Kannan, Yong- Huat Chew, Chin-Choy Chai, Hongyi Fu, Manjeet, Tung-Chong Wong, T.T. Tjhung, Zhongding Lei, Rahim]
Company: [Institute for Infocomm Research, Singapore]
Address: [21 Heng Mui Keng Terrace, Singapore ]
Voice: [ ] FAX: [ ]
Re: [Response to the call for proposal of IEEE b, Doc Number: b]
Abstract: [This presentation compares all proposals for the IEEE b PHY standard.]
Purpose: [Proposal to IEEE b Task Group]
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
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

2. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Sept 2004
Proposed Code Sequences
for IEEE a Alt-PHY
Francois Chin
Institute for Infocomm Research
Singapore
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

3. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Sept 2004
Proposed System Parameters
Chip rate
16 Mcps
Pulse Rep. Freq.
16 MHz
Symbol Rate
0.5 MHz
Min. info. bit / sym.
4 bit / symbol
Max bit rate
4 x 0.5 = 2.0 Mbps
# Chip / symbol (Code length) 32
#Code Sequences/ piconet
16 (4 bit/symbol)
Code position modulation (CPM)
Lower bit rate
250 kbps (2-layer CPM)
31.25 kbps (3-layer CPM)
kbps (4-layer CPM)
Modulation
BPSK or On-Off Keying (OOK)
Total # simultaneous piconets supported 6
Multple access for piconets
Fixed band and sequence for each piconet
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

4. doc.: IEEE 802.15-<doc#>
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doc.: IEEE <doc#>
Sept 2004
Code Sequence Set
Seq 1
Seq 2
Seq 3
Seq 4
Seq 5
Seq 6
31-chip M-Sequence set
Only one sequence and one fixed band (no hopping) will be used by all devices in a piconet
Logical channels for support of multiple piconets
6 sequences = 6 logical channels (e.g. overlapping piconets)
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

5. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Sept 2004
Gray Coded Code Position Modulation (CPM)
Symbol
Cyclic shift to right by n chips, n=
32-Chip value
0000
0001 2
0011 4
0010 6
0110 8
0111 10
0101 12
0100 14
1100 16
1101 18
1111 20
1110 22
1010 24
1011 26
1001 28
1000 30
To obtain 32-chip per symbol, cyclic shift first, then extend 1-chip
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

6. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Sept 2004
Cyclic Extended Chip
To avoid / reduce inter-symbol interference in channels with excess delay spread
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

7. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Sept 2004
Properties of M-Sequences
Cyclic auto-correlation of any antipodal sequence gives peak value of 31 and sidelobe value of -1 throughout
Cyclic correlation of any antipodal sequence with its corresponding uni-podal sequence give peak value of 16 and zero sidelobe throughout
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

8. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Sept 2004
Inter-Piconet Interference Suppression
With one overlapping piconet with asynchronous operation, the average interference suppression capability is 13.7dB
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

9. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Sept 2004
N-layer CPM
To increase spreading gain to achieve reduce bit rate operation & coding gain
Operation - The output of the symbol-to-chip mapper is fed into the same symbol-to-chip mapper for N times
With N = 2, 4 bits is mapper to 32/4*32 = 256 chips
With N = 3, 4 bits is mapper to 32/4*32 /4 * 32 = 2048 chips
Example of 3-layer CPM (for kbps)
0001 ….
16 Mcps
2 Mcps
250 kcps
31.25 kbps
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

10. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Sept 2004
Coding Gain of multiple-layer CPM
AWGN BER=10-5
1-layer over PBSK: ~2.5 dB
2-layer over 1-layer: ~ 5 dB
3-layer over 2-layer: ~ 3.5 dB
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

11. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Sept 2004
Synchronisation Preamble
Correlator output for synchronisation
Code sequence has excellent autocorrelation properties
Preamble is constructed by repeating base Code Sequence
Unique – no symbol & spreading combination can construct this preamble
Unlike 15.4, where preamble is constructed by 8x ‘0000’ symbols
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

12. doc.: IEEE 802.15-<doc#>
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doc.: IEEE <doc#>
Sept 2004
Summary
Advantages of M-Sequence Codes
Low auto-correlation
One sequence for the entire piconet for
Better synchronisation / acquisition performance due to low autocorrelation properties;
Simple symbol-to-chip mapping;
Further symbol spreading through self-generation layered mechanism to achieve considerable coding gains, leading to better coverage at reduced bit rate operations
Reasonably good suppression capability for simultaneous operating piconets
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>