1. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Jan 2005
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Proposed Code Sequences for IEEE a Alt-PHY]
Date Submitted: [Jan 2005]
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 a, Doc Number: a ]
Abstract: [I2R’s Proposal to IEEE a Task Group]
Purpose: [For presentation and consideration by the IEEE a committee]
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#>
Jan 2005
Proposed Code Sequences,
Modulation & Coding
for IEEE a Alt-PHY
Francois Chin
Institute for Infocomm Research
Singapore
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

3. Jan 2005
Proposal Motivation
To satisfy IEEE a technical requirements, low power consumption is crucial
Conventional coherent UWB system based on correlator in the receiver can provide fairly good performance, but at the expense of implementation complexity, and consequently power consumption and system cost
To meet low power and low cost requirement, UWB system with OOK (On-Off Keying) modulation and noncoherent detection is proposed
In the proposed UWB OOK system, the signal demodulation is performed by simply integrating signal energy, thus omitting signal / pulse generator, significantly relieve the strict synchronization requirement and greatly simplify transceiver structure with the minimal power and cost demand
However, some challenges of such OOK system are threshold setting, simultaneous operating piconets (SOP) & timing boundaries estimation
This proposal contains techniques that will overcome such limitation, and improve the overall system performance of the UWB OOK system
Francois Chin, Institute for Infocomm Research (I2R)

4. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Jan 2005
Proposed System Parameters
Chip rate
11 Mcps **
# Pulse / Chip Period 12
Pulse Rep. Freq.
11 x 12 MHz = 132 MHz
# Chip / symbol (Code length) 32
Symbol Rate
11/32 MHz = kHz
Min. info. bit / sym.
4 bit / symbol
Max bit rate
4 x kHz = Mbps
Mandatory bit rate
1.375 Mbps / 5 (x Symbol Repetition) = 275kbps
#Code Sequences/ piconet
16 (4 bit/symbol)
Code position modulation (CPM)
Lower bit rate scalability
Symbol Repetition
Modulation / Demodulation
Ternary {+1,-1,0} pulse train /
On-Off Keying (OOK)
Total # simultaneous piconets supported 6
Multple access for piconets
Fixed sequence for each piconet
** Proposed chip rate of 11 MHz is a common denominator in the clock rate of 11a/b/g, MB-OFDM and DS-UWB
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

5. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Jan 2005
UWB Pulse & Spectrum
1.5 ns rectified cosine shape
~1400 MHz 10-dB bandwidth
Centre frequency ~4 GHz
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

6. Modulation & Coding Jan 2005 Binary data From PPDU Bit-to- Symbol
Scrambling {+1,-1} Sequence
{0,1} Sequence
Bit-to-
Symbol
Symbol-
to-Chip
Chip
Repetition
Chip
Scrambler
Pulse
Generator
{0,+1,-1} Sequence
Bit to symbol mapping:
group every 4 bits into a symbol
Symbol-to-chip mapping:
Each symbol is mapped to a 32-chip {0,1} sequence, according to Gray Coded Code Position Modulation (CPM)
Chip Repetition (11 Mcps):
Factor of K=5 corresponds to 275 kbps (Mandatory Mode)
Chip Scrambling (11 Mcps):
the K x 32-chip {0,1} sequence is mutliplied with random scrambing {+1,-1} sequence
this is to avoid spectral spikes
Pulse Generator (11 x 12 = 132 MHz):
Chips are repetited and Ternary -modulated
chip = ‘+1'  12 +ve pulse are 132 MHz
chip = ‘-1'  12 -ve pulse are 132 MHz
chip = '0'  no pulse
Francois Chin, Institute for Infocomm Research (I2R)

7. Multiple access Multiple access within piconet: same as 15.4.
Jan 2005
Multiple access
Multiple access within piconet: same as 15.4.
Multiple access across piconets: CDMA.
Different Piconet uses different Base Sequence
Francois Chin, Institute for Infocomm Research (I2R)

8. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Jan 2005
Base 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)
The same base sequence will be used to construct the symbol-to-chip mapping table
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

9. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Jan 2005
Symbol-to-Chip Mapping:
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 the Base Sequence first, then extend 1-chip
Base Sequence #1
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

10. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Jan 2005
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 correlation with other 15 uni-podal sequences with give zero sidelobe throughout
i.e. Each transmit OOK sequence will give a peak correlator output at a correlator with its corresponding antipodal sequence & ZERO at other 15 correlators
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

11. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Jan 2005
Cyclic Extended Chip
To avoid / reduce inter-symbol interference in channels with excess delay spread
To ensure zero inter-chip interference in receiver correlator output
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

12. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Jan 2005
Synchronisation Preamble
Correlator output for synchronisation
Code sequences has excellent autocorrelation properties
Preamble is constructed by repeating Sequence ‘0000’
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>

13. The transmitter Guide Line : Keep it Simple
Jan 2005
The transmitter
Guide Line : Keep it Simple
Main Goal : "Low cost & low consumption"
Pulses are generated in baseband
No mixer, no VCO but pulse shaping
Simple control logic and "reasonable" clock frequency (Crystal)
PSDU Data
Clock
F = 132MHz
Control Logic
BaseBand signal
RF Signal
Pulse Generator
PA (option)
Pulse shaper
Francois Chin, Institute for Infocomm Research (I2R)

14. Jan 2005
The receiver
Fc=5.5MHz
BPF
( )2
LPF
ADC
Soft
Despread
Energy detection technique rather than coherent receiver, for relaxed synchronization constraints
Soft chip values gives best results
Oversampling & sequence correlation is used to recovery chip timing recovery
Synchronization fully re-acquired for each new packet received (=> no very accurate timebase needed)
Low cost, low complexity
22 MHz Sample Rate
Francois Chin, Institute for Infocomm Research (I2R)

15. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Jan 2005
Frame Format
Octets: 2 1
0/4/8 n 2
MAC
Sublayer
Frame
Cont.
Data Payload
Seq. #
Address
CRC
MHR
MSDU
MFR
Octets:
TBD 1 1
Data: 32 (n=23)
For ACK: 5 (n=0)
PHY
Layer
Frame
Length
Preamble
SFD
MPDU
SHR
PHR
PSDU
PPDU
Francois Chin, Institute for Infocomm Research (I2R)
<author>, <company>