IEEE 802.15 <PHY Proposal>

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Project IEEE P802.15 Working Group for Wireless
Personal Area Networks (WPANs) Submission Title
Proposed Code Sequences for IEEE 802.15.4a
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 119613 Voice 65-68745684
FAX [phone] E-Mail chinfrancois_at_i2r.a-
star.edu.sg Re Response to the call for
proposal of IEEE 802.15.4b, Doc Number
15-04-0239-00-004b Abstract This presentation
compares all proposals for the IEEE802.15.4b PHY
standard. Purpose Proposal to IEEE 802.15.4b
Task Group 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.
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Proposed Code Sequences for IEEE 802.15.4a
Alt-PHY

• Francois Chin
• Institute for Infocomm Research
• Singapore

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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) 3.90625 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
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Code Sequence Set
Seq 1 1 1 1 0 0 0 1 1 0 1 1 1 0 1 0 1 0 0 0 0 1 0 0 1 0 1 1 0 0 1 1
Seq 2 1 0 1 1 1 0 0 0 1 0 1 0 1 1 0 1 0 0 0 0 1 1 0 0 1 0 0 1 1 1 1
Seq 3 1 1 0 1 1 1 1 1 0 1 0 0 0 1 0 0 1 0 1 0 1 1 0 0 0 0 1 1 1 0 0
Seq 4 0 1 0 1 1 1 0 1 1 0 0 0 1 1 1 1 1 0 0 1 1 0 1 0 0 1 0 0 0 0 1
Seq 5 1 1 1 1 0 0 1 0 0 1 1 0 0 0 0 1 0 1 1 0 1 0 1 0 0 0 1 1 1 0 1
Seq 6 0 0 1 1 1 0 0 0 0 1 1 0 1 0 1 0 0 1 0 0 0 1 0 1 1 1 1 1 0 1 1

• 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)

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Gray Coded Code Position Modulation (CPM)
Symbol Cyclic shift to right by n chips, n 32-Chip value
0000 0 1 1 1 0 0 0 1 1 0 1 1 1 0 1 0 1 0 0 0 0 1 0 0 1 0 1 1 0 0 1 1 1
0001 2 1 1 1 1 1 0 0 0 1 1 0 1 1 1 0 1 0 1 0 0 0 0 1 0 0 1 0 1 1 0 0 0
0011 4 0 0 1 1 1 1 1 0 0 0 1 1 0 1 1 1 0 1 0 1 0 0 0 0 1 0 0 1 0 1 1 0
0010 6 1 1 0 0 1 1 1 1 1 0 0 0 1 1 0 1 1 1 0 1 0 1 0 0 0 0 1 0 0 1 0 1
0110 8 1 0 1 1 0 0 1 1 1 1 1 0 0 0 1 1 0 1 1 1 0 1 0 1 0 0 0 0 1 0 0 1
0111 10 0 0 1 0 1 1 0 0 1 1 1 1 1 0 0 0 1 1 0 1 1 1 0 1 0 1 0 0 0 0 1 0
0101 12 0 1 0 0 1 0 1 1 0 0 1 1 1 1 1 0 0 0 1 1 0 1 1 1 0 1 0 1 0 0 0 0
0100 14 0 0 0 1 0 0 1 0 1 1 0 0 1 1 1 1 1 0 0 0 1 1 0 1 1 1 0 1 0 1 0 0
1100 16 1 0 0 0 0 1 0 0 1 0 1 1 0 0 1 1 1 1 1 0 0 0 1 1 0 1 1 1 0 1 0 1
1101 18 1 0 1 0 0 0 0 1 0 0 1 0 1 1 0 0 1 1 1 1 1 0 0 0 1 1 0 1 1 1 0 1
1111 20 1 0 1 0 1 0 0 0 0 1 0 0 1 0 1 1 0 0 1 1 1 1 1 0 0 0 1 1 0 1 1 1
1110 22 1 1 1 0 1 0 1 0 0 0 0 1 0 0 1 0 1 1 0 0 1 1 1 1 1 0 0 0 1 1 0 1
1010 24 1 0 1 1 1 0 1 0 1 0 0 0 0 1 0 0 1 0 1 1 0 0 1 1 1 1 1 0 0 0 1 1
1011 26 0 1 1 0 1 1 1 0 1 0 1 0 0 0 0 1 0 0 1 0 1 1 0 0 1 1 1 1 1 0 0 0
1001 28 0 0 0 1 1 0 1 1 1 0 1 0 1 0 0 0 0 1 0 0 1 0 1 1 0 0 1 1 1 1 1 0
1000 30 0 0 0 1 1 0 1 1 1 0 1 0 1 0 0 0 0 1 0 0 1 0 1 1 0 0 1 1 1 1 1 0
To obtain 32-chip per symbol, cyclic shift first,
then extend 1-chip
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Cyclic Extended Chip

• To avoid / reduce inter-symbol interference in
  channels with excess delay spread

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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

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Inter-Piconet Interference Suppression

• With one overlapping piconet with asynchronous
  operation, the average interference suppression
  capability is 13.7dB

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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 32/432 256
  chips
• With N 3, 4 bits is mapper to 32/432 /4 32
  2048 chips

Example of 3-layer CPM (for 31.25 kbps)
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Coding Gain of multiple-layer CPM

• AWGN performance _at_ BER10-5
• 1-layer over PBSK 2.5 dB
• 2-layer over 1-layer 5 dB
• 3-layer over 2-layer 3.5 dB

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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

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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