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July 2010
I2R, VinnoSlide 1
Doc.: IEEE 802.15-10-00281-04-004g
Submission
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)(WPANs)
Submission Title: [New C(8,4) chip sequence for Multi-rate OQPSK Modulation]
Date Submitted: [12, May, 2010]
Source: [Francois Chin, Yuen-Sam Kwok, Liang Zhang, Liang Li, Tao Xin, Haitao Liu] Company: [Institute for Infocomm Research, Singapore, Vinno, Huawei, SIMIT]
Address: [1 Fusionopolis Way #21-01 Connexis South Tower, Singapore 138632]
Voice: [65-6408-2530] FAX: []
E-Mail: [[email protected], [email protected] [email protected]]
Re: [Response to the call for proposal of IEEE 802.15.4G]
Abstract: [This presentation compares all proposals for the IEEE802.15.4G standard.]
Purpose: [Proposal to IEEE 802.15.4G 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.
July 2010
I2R, VinnoSlide 2
Doc.: IEEE 802.15-10-00281-04-004g
Submission
Current (8,4)-DSSS code sequence for high rate mode does not support non-coherent receiver.
It is desirable choose a code sequences that supports low-complexity non-coherent receiver.
Motivation
July 2010
I2R, VinnoSlide 3
Doc.: IEEE 802.15-10-00281-04-004g
Submission
Current C(8,4) in Std draftDecimal Value Binary Symbol Chip Value
0 0000 00000001
1 1000 11010000
2 0100 01101000
3 1100 10111001
4 0010 11100101
5 1010 00110100
6 0110 10001100
7 1110 01011101
8 0001 10100010
9 1001 01110011
10 0101 11001011
11 1101 00011010
12 0011 01000110
13 1011 10010111
14 0111 00101111
15 1111 11111110
July 2010
I2R, VinnoSlide 4
Doc.: IEEE 802.15-10-00281-04-004g
Submission
Cross-correlation Characteristics for Current C(8,4) in Std draft
No modulation; no over-sampling (all in real numbers)
(a) cross-correlations of all 16 COBI-C8 codes (b) cross-correlation of one COBI-C8 code
July 2010
I2R, VinnoSlide 5
Doc.: IEEE 802.15-10-00281-04-004g
Submission
(a) cross-correlations of all 16 COBI-C8 codes (b) cross-correlation of one COBI-C8 code
With O-QPSK modulation; 2x over-sampling (complex domain)
Cross-correlation Characteristics for Current C (8,4) in Std draft
July 2010
I2R, VinnoSlide 6
Doc.: IEEE 802.15-10-00281-04-004g
Submission
The sequences are related to each other through cyclic shifts and odd-bit inversion.The first 8 and last symbols are both shifted versions of each other .
Proposed New Symbol-to-Chip Mapping (8-chip Code Set C8)
Decimal Value Binary Symbol Chip Value
0 0000 0 1 0 1 1 1 0 0 (Root – 5C)
1 1000 0 0 1 0 1 1 1 0
2 0100 0 0 0 1 0 1 1 1
3 1100 1 0 0 0 1 0 1 1
4 0010 1 1 0 0 0 1 0 1
5 1010 1 1 1 0 0 0 1 0
6 0110 0 1 1 1 0 0 0 1
7 1110 1 0 1 1 1 0 0 0
8 0001 0 0 0 0 1 0 0 1
9 1001 1 0 0 0 0 1 0 0
10 0101 0 1 0 0 0 0 1 0
11 1101 0 0 1 0 0 0 0 1
12 0011 1 0 0 1 0 0 0 0
13 1011 0 1 0 0 1 0 0 0
14 0111 0 0 1 0 0 1 0 0
15 1111 0 0 0 1 0 0 1 0
July 2010
I2R, VinnoSlide 7
Doc.: IEEE 802.15-10-00281-04-004g
Submission
Search Based: Other Root Sequences
(8-chip C8 for Coherent Despreading only)
• The following Root Sequences are found through exhaustive search with identical low cross correlation and autocorrelation, in base 10:
9 18 23 29 33 36 46 58 66 71 72 92 111 113 116 123 132 139 142 144 163 183 184 189 197 209 219 222 226 232 237 246
July 2010
I2R, VinnoSlide 8
Doc.: IEEE 802.15-10-00281-04-004g
Submission
No modulation; no over-sampling (all in real numbers)
(a) cross-correlations of all 16 COBI-C8 codes (b) cross-correlation of one COBI-C8 code
Cross-correlation Characteristics for Proposed C8
July 2010
I2R, VinnoSlide 9
Doc.: IEEE 802.15-10-00281-04-004g
Submission
(a) cross-correlations of all 16 COBI-C8 codes (b) cross-correlation of one COBI-C8 code
With O-QPSK modulation; 2x over-sampling (complex domain)
Cross-correlation Characteristics for Proposed C8
July 2010
I2R, VinnoSlide 10
Doc.: IEEE 802.15-10-00281-04-004g
Submission
Comparison
cross-correlation of one Current C(8,4) code cross-correlation of one Proposed C8 code
Several Peaks of the cross-correlation of the Current C(8,4) will introduce more demodulation error with coherent or non-coherent receiver. Hence, the Proposed C8 with
only one Peak of the cross-correlation has better demodulation performance.
July 2010
I2R, VinnoSlide 11
Doc.: IEEE 802.15-10-00281-04-004g
Submission
Cross-correlation Characteristics
• The cross-correlation of current C(8, 4) (slide 4) indicates that decoding of the correct symbol based on maximum magnitude of correlation value is not possible
July 2010
I2R, VinnoSlide 12
Doc.: IEEE 802.15-10-00281-04-004g
Submission
Autocorrelation Characteristics of C8
Autocorrelation of all 16 COBI-C8 sequences
No modulation; no over-sampling (all in real numbers)
July 2010
I2R, VinnoSlide 13
Doc.: IEEE 802.15-10-00281-04-004g
Submission
Autocorrelation Characteristics of C8
Autocorrelation of all 16 COBI-C8 sequences
O-QPSK modulation; 2x over-sampling (complex domain)
July 2010
I2R, VinnoSlide 14
Doc.: IEEE 802.15-10-00281-04-004g
Submission
The Benefits of Proposed C8 code
• The Correlation Calculation is still the basic processing for Decoding.
• The stronger auto-correlation and improved cross correlation may decrease the PER
• The Proposed code sequences are a round-shift of two essential codes.
July 2010
I2R, VinnoSlide 15
Doc.: IEEE 802.15-10-00281-04-004g
Submission
Simulation parameters & assumptions:
– O-QPSK + Raised cosine pulse shape with roll-off factor = 0.8
– 20 octets in each packet– 20,000 packets for Monte-Carlo simulation– No Sync error– No SFD detection– Both Coherent and Non-coherent demodulation
System Performance
July 2010
I2R, VinnoSlide 16
Doc.: IEEE 802.15-10-00281-04-004g
Submission
The Definition for Coherent and Non-Coherent Receivers
• Coherent receiver– phase of received signal is synchronized– symbol detection based on maximum
correlation value
• Non-coherent receiver– phase of received signal is not
synchronized– symbol detection based on magnitude of
correlation value
July 2010
I2R, VinnoSlide 17
Doc.: IEEE 802.15-10-00281-04-004g
Submission
Performance Comparison (BER)
July 2010
I2R, VinnoSlide 18
Doc.: IEEE 802.15-10-00281-04-004g
Submission
Performance Comparison (PER)
July 2010
I2R, VinnoSlide 19
Doc.: IEEE 802.15-10-00281-04-004g
Submission
• New proposed COBI-Cs has the better cross-correlation
Characteristics • The Proposed code sequences are a round-shift of two
essential codes.• For low-complexity non-coherent receiver, New proposed COBI-
C8 performance is much better.
Suggestion: Adopt New Cobi-C8 chip sequence and instead of the current C(8,4) sequence in draft.
Summary and Suggestion
