1. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
March 2005
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Enhanced E16 Code with Offset QPSK for b High Rate Alt-PHY]
Date Submitted: [13 Jan, 2004]
Source: [Liang Zhang, Hongyu Gu, Liang Li, Yafei Tian, Chenyang Yang, Zhijian Hu, Yong Guan] Company: [WXZJ Inc.]
Address: [2 Xinxi St, Building D, Haidian District, Beijing, China ]
Voice:[ ],
Re: [Response to the call for proposal of IEEE 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
Liang Li, WXZJ
<author>, <company>

2. March 2005
Motivation
Choose DSSS code sequences that will lead to efficient transmission and low implementation complexity.
Liang Li, WXZJ

3. Six desirable properties of DSSS code sequences
March 2005
Six desirable properties of DSSS code sequences
All sequences contain equal number of ones and zeros
All sequences contain equal number of ones and zeros in the even numbered chips (I phase)
All sequences contain equal number of ones and zeros in the odd numbered chips (Q phase)
Total phase rotation in I / Q plane accumulates to 0 degree over a complete symbol period
The first 8 symbols are shifted versions of each other
The last 8 symbols have inverted odd numbered chips (Q phase); when compared to the 8 first symbols, have the exact inverted baseband phase
Liang Li, WXZJ

4. Issue: Non-zero DC value of E16 DSSS Sequence
March 2005
Issue: Non-zero DC value of E16 DSSS Sequence
DC values
Decimal Symbol
Binary Symbol
Chip Values 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Total DC values = -16
Source doc.: IEEE b
Liang Li, WXZJ

5. Proposed Symbol-to-Chip Mapping (Enhanced 16-chip Code Set W16)
March 2005
Proposed Symbol-to-Chip Mapping (Enhanced 16-chip Code Set W16)
Decimal Value
Binary Symbol
Chip Value
DC Value
0000 1
1000 2
0100 -4 3
1100 4
0010 4i 5
1010
–4i 6
0110
-4 –4i 7
1110
4 -4i 8
0001 9
1001 10
0101 11
1101 12
0011 13
1011
4+4i 14
0111 15
1111
Total DC Value
0 +0i
Liang Li, WXZJ

6. The Features of W16 Sequences
March 2005
The Features of W16 Sequences
l Having same features of DSSS sequences of std:
1.  Equal number of “0”s and “1”s in preamble sequence;
2.  The first chip is not always 0 or 1;
3.  Total DC value is 0, even though not always 0 in every sequence;
4.  The phase comes back to 0 after one symbol period.
l Maintaining good characteristics of E16 sequences:
1.  Orthogonality characteristics introduced by Walsh conversion;
2.  Performance similar to that of E16 orthogonal sequences;
3.  Low complexity of correlation decoder implementation.
Liang Li, WXZJ

7. Key Parameters of W16 (1) Bit rate of 250 kBit/s
March 2005
Key Parameters of W16 (1)
Bit rate of 250 kBit/s
Better orthogonal characteristic
16 sequences for 4 bits mapping
Each consisting of 16 chips
Chip rate = 1Mchips per second
Center frequency = 915MHz;
Bandwidth, pulse shape,PAPR, frequency offset
The 1st null-null bandwidth 1.5MHz;
Half-sine pulse shape;
0dB PAPR, same MSK scheme as 15.4, constant modulus and continuous phase, lower out-of-band emission;
PSD: 30dB lower over 2MHz-wide bandwidth, conforming to std;
Frequency offset tolerance over 40ppm;
Liang Li, WXZJ

8. Key Parameters of W16 (2) Multipath fading robustness
March 2005
Key Parameters of W16 (2)
Multipath fading robustness
Achieving PER<10-2 in multipath channels of 250ns rms delay spread (channel model suggested by Paul)
Support of current RF
Support 2 MHz-wide channels as allocated in the USA and other countries
Low cost and low power consumption
Liang Li, WXZJ

9. PSD of W16 Bandwidth, Pulse shape:
March 2005
PSD of W16
Bandwidth, Pulse shape:
The 1st null-null bandwidth 1.5MHz; Half-sine pulse shape:
MSK modulation offers constant modulus and continuous phase;
PSD 30dB lower at 1.5MHz from center frequency.
Liang Li, WXZJ

10. W16 PSD characteristic PSD of W16 is not affected by sampling error.
March 2005
W16 PSD characteristic
PSD of W16 is not affected by sampling error.
Low out-of-band emission: no need for Tx filter
Satisfies the IEEE PSD requirements
Source: IEEE Standard
Liang Li, WXZJ

11. Auto-correlation performance
March 2005
Auto-correlation performance
Synchronization performance of W16 based on simulations:
Auto-correlation characteristics with MSK modulation in 2x sampling rate
Synchronization performance in the presence of frequency offset
Liang Li, WXZJ

12. The Auto-Correlation of W16 and En- Cobi 16
March 2005
The Auto-Correlation of W16 and En- Cobi 16
En-Cobi 16
W16
In this test, the correlations are calculated after spreading sequences are OQPSK modulated with half-sine pulse shaping.
Liang Li, WXZJ

13. Cross-correlation of received Signals of W16 and En-Cobi16
March 2005
Cross-correlation of received Signals of W16 and En-Cobi16
W16
En-Cobi16
(2x over sampling rate)
Liang Li, WXZJ

14. Frequency offset performance
March 2005
Frequency offset performance
Simulation parameters & assumptions:
Rayleigh Channel model as suggested at TG4 discussions
O-QPSK + half-sine pulse shaping
2M sampling rate (1M chips/sec)
Frequency offset from 0ppm to 40ppm
Center frequency = 915MHz
Average over 1 million Monte-Carlo simulations
Notes:
Synchronization is achieved by correlating local PN with received preamble impaired by frequency offset.
Throughout this document, the perfect synchronization (no error) in a multipath environment is defined as the receiver being synchronized to the strongest path.
Liang Li, WXZJ

15. Frequency offset performance: simulations
March 2005
Frequency offset performance: simulations
Sync performance
BER performance
Frequency offset affects the sync and decoding performance significantly. So, frequency offset should be considered in 154b system.
Liang Li, WXZJ

16. Preamble here proposed for 15.4b:
March 2005
Proposal for preamble
Preamble of 15.4 standard:
Preamble here proposed for 15.4b:
The preamble field proposed here consists of at least 4 octets (prefer 6 octets).
Liang Li, WXZJ

17. System performance comparison between W16 and COBI16
March 2005
System performance comparison between W16 and COBI16
Simulation parameters & assumptions:
250ns rms delay spread Rayleigh Channel model
O-QPSK modulation + half sine pulse
without frequency offset
without synchronization error
20 octets in each packet
10,000 packets for Monte-Carlo simulation
Non-coherent demodulation
No SFD detection
No fading
The solid curve indicates the performance of W16 and the dash one indicates the performance of COBI16
Liang Li, WXZJ

18. System Simulation Models
March 2005
System Simulation Models
Discrete exponential channel model:
– Sampled version of diffuse channel model offer by Paul with 4MHz sampling rate;
–At least random channel realizations;
–PER calculated on 20 bytes PPDUs with preamble.
Liang Li, WXZJ

19. AWGN: Ideal Sync. vs. Correlation Sync.
March 2005
AWGN: Ideal Sync. vs. Correlation Sync.
Packet Number: 10000
PSDU Length: 20 Byte
Tx/Rx Over Sample Rate: 2
Channel Over Sample Rate: 4
Frame Detection: No
SFD: No
Liang Li, WXZJ

20. Multipath channel: no fading + correlation sync (1)
March 2005
Multipath channel: no fading + correlation sync (1)
Packet Number: 10000
PSDU Length: 20 Byte
Tx/Rx Over Sample Rate: 2
Channel Over Sample Rate: 4
Time offset: No
Frame Detection: No
Phase noise :No
SFD: No
Sync.: Correlation
Down sampling error: No
Liang Li, WXZJ

21. Multipath channel: no fading + correlation sync (2)
March 2005
Multipath channel: no fading + correlation sync (2)
Packet Number: 10000
PSDU Length: 20 Byte
Tx/Rx Over Sample Rate: 2
Channel Over Sample Rate: 4
Time offset: No
Frame Detection: No
Phase noise :No
SFD: No
Sync.: Correlation
Down sampling error: Yes
Liang Li, WXZJ

22. Multipath channel: no fading + correlation sync (3)
March 2005
Multipath channel: no fading + correlation sync (3)
Packet Number: 10000
PSDU Length: 20 Byte
Tx/Rx Over Sample Rate: 2
Channel Over Sample Rate: 4
Time offset: Yes
Frame Detection: No
Phase noise :No
SFD: No
Sync.: Correlation
Down sampling error: No
Liang Li, WXZJ

23. Multipath channel: no fading + correlation sync (4)
March 2005
Multipath channel: no fading + correlation sync (4)
Frame Detection: No
Phase noise :YES
SFD: No
Sync.: Correlation
Down sampling error: No
Packet Number: 10000
PSDU Length: 20 Byte
Tx/Rx Over Sample Rate: 2
Channel Over Sample Rate: 4
Time offset: No
Liang Li, WXZJ

24. Multipath channel: no fading + correlation sync (5)
March 2005
Multipath channel: no fading + correlation sync (5)
Frame Detection: No
Phase noise :YES
SFD: YES
Sync.: Correlation
Down sampling error: No
Packet Number: 10000
PSDU Length: 20 Byte
Tx/Rx Over Sample Rate: 2
Channel Over Sample Rate: 4
Time offset: No
Liang Li, WXZJ

25. Multipath channel: no fading + correlation sync (6)
March 2005
Multipath channel: no fading + correlation sync (6)
Frame Detection: YES
Phase noise :YES
SFD: Yes
Sync.: Correlation
Down sampling error: No
Packet Number: 10000
PSDU Length: 20 Byte
Tx/Rx Over Sample Rate: 2
Channel Over Sample Rate: 4
Time offset: No
Liang Li, WXZJ

26. Multipath channel: no fading + correlation sync (7)
March 2005
Multipath channel: no fading + correlation sync (7)
Frame Detection: YES
Phase noise :YES
SFD: Yes
Sync.: Correlation
Down sampling error: Yes
Packet Number: 10000
PSDU Length: 20 Byte
Tx/Rx Over Sample Rate: 2
Channel Over Sample Rate: 4
Time offset: No
Liang Li, WXZJ

27. Multipath channel: no fading + correlation sync (8)
March 2005
Multipath channel: no fading + correlation sync (8)
Packet Number: 10000
PSDU Length: 20 Byte
Tx/Rx Over Sample Rate: 2
Channel Over Sample Rate: 4
Time offset: Yes
Frame Detection: YES
Phase noise :YES
SFD: Yes
Sync.: Correlation
Down sampling error: Yes
Liang Li, WXZJ

28. March 2005
Multipath channel without Fading + Correlation Sync. (frequency offset estimation)
Packet Number: 10000
PSDU Length: 20 Byte
Tx/Rx Over Sample Rate: 2
Channel Over Sample Rate: 4
Time offset: Yes
Frame Detection: YES
Phase noise :YES
SFD: Yes
Sync.: Correlation
Down sampling error: Yes
Liang Li, WXZJ

29. Multipath channel with fading + correlation Sync (1)
March 2005
Multipath channel with fading + correlation Sync (1)
Frame Detection: No
Phase noise: No
SFD: No
Sync.: Correlation
Down sampling error: No
Packet Number: 10000
PSDU Length: 20 Byte
Tx/Rx Over Sample Rate: 2
Channel Over Sample Rate: 4
Time offset: No
Liang Li, WXZJ

30. Multipath channel with fading + correlation Sync (2)
March 2005
Multipath channel with fading + correlation Sync (2)
Frame Detection: Yes
Phase noise :Yes
SFD: Yes
Sync.: Correlation
Down sampling error: No
Packet Number: 10000
PSDU Length: 20 Byte
Tx/Rx Over Sample Rate: 2
Channel Over Sample Rate: 4
Time offset: No
Liang Li, WXZJ

31. Nonlinear PA Characteristics
March 2005
Nonlinear PA Characteristics
Liang Li, WXZJ

32. Impact of PA Nonlinearity: 2x sampling rate
March 2005
Impact of PA Nonlinearity: 2x sampling rate
(1) Tx PSD without PA
(2) Tx PSD with PA
For the constant module and continuous phase in our proposal, the Tx PSD is not affected by nonlinear PA.
Liang Li, WXZJ

33. Summary Enhanced W16 can satisfy the 6 criteria
March 2005
Summary
Enhanced W16 can satisfy the 6 criteria
No spikes in frequency spectrum
The sync performance using correlation method is the same as the COBI16 (d1), and the performance of demodulation is slightly better than that of COBI16(d1)
The system PER performance of W16 is slightly better than that of COBI16(d1), especially in condition of large delay spread
Liang Li, WXZJ