1. Source: [Yafei Tian, Chenyang Yang, Liang Li ]
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [The Difference on PHY layer between Chinese WPAN and IEEE ]
Date Submitted: [Dec. 19, 2006 ]
Source: [Yafei Tian, Chenyang Yang, Liang Li ]
Company: [Beihang University (BUAA), Vinno Technologies Inc. ]
Address: [2 Xinxi St, Building D, Haidian District, Beijing, China ]
Voice:[ ], ,
Re: [ Chinese Wireless PAN Group]
Abstract: [Description the major difference on PHY Layer between IEEE802.15WG and Chinese WPAN WG]
Purpose: [To encourage discussion.]
Notice: This document has been prepared to assist the Chinese WPAN group. 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 C- WPAN and may be made publicly available by C-WPAN.
Submission
BUAA, Vinno

2. Outline
Review of the proposed communication technique in C-WPAN PHY draft standard.
Major difference with IEEE MHz band PHY
Spreading sequence
SFD design
Pulse shaping filter
Synchronization and demodulation performance
Submission
BUAA, Vinno

3. Frequency bands and Data rate
PHY
(MHz)
Frequency Bands
Spreading Parameters
Data Parameters
Chip Rate
(Mchip/s)
Modulation
Bit Rate
(kb/s)
Symbol Rate
(ksymbol/s)
315
0.2
Chirp Sequence
+ MPSK 50
12.5
430
780 1
250
62.5
2400 2
Quasi-orthogonal
Binary Sequence
+ O-QPSK
Submission
BUAA, Vinno

4. Reference Design of the Wireless Transceiver
Submission
BUAA, Vinno

5. Spreading Sequence and Mapping
The Direct Sequence Spread Spectrum (DSSS) tech is applied
16 orthogonal spreading sequences are designed to map 4 information bits. The base sequence is a 16 length chirp sequence and the other 15 sequences are its cyclic shifts.
Submission
BUAA, Vinno

6. Pre-processing Conjugate the first sequence to obtain SFD
The SFD sequence is the conjugate of the Preamble sequence, that means the phases of the SFD chips are adverse to the phases of the Preamble chips.
DC component removal
All chips of each symbol in the head and load of PPDU should be multiplied by –1 or 1 based on the follow PN code serials.
Submission
BUAA, Vinno

7. Pulse Shaping and Spectrum
The Pulse Shaping Filter on I and Q path is designed as a raised cosine filter with roll-off factor 0.5:
The Transmit waveform and Spectrum are :
Submission
BUAA, Vinno

8. Difference 1: Frequency Bands
C-WPAN:
Radio Management Office of P.R.China (Supervised by Ministry of Info Industry) approved the following frequency bands and TX power limitation for the operation of WPAN equipment
MHz, Pt <=10mw (e.i.r.p)
Channel separation is 2MHz, channel number is 4.
MHz band optional PHY:
MHz
Channel separation is 2MHz, channel number is 10.
Submission
BUAA, Vinno

9. Difference 2: Spreading Sequence
C-WPAN:
Chirp code is orthogonal among its cyclic shifts
Perfect auto-correlation property of the Preamble sequence,
Perfect orthogonal property of the 16 spreading sequences,
Reduce inter-chip interference in multipath environments.
Chirp code is robust to frequency offset
Low cost implementation of transmitter and receiver.
MHz band optional PHY:
16 sequences are quasi-orthogonal.
The auto-correlation property of the Preamble sequence is not very well.
The code is susceptible to frequency offset.
Submission
BUAA, Vinno

10. Sliding Correlation Values of the Preamble Sequence
With Sequence in C-WPAN Draft Std
With Sequence in Std
Submission
BUAA, Vinno

11. Difference 3: SFD Design
C-WPAN:
The 16 spreading sequences are cyclic shift of each other.
The SFD sequence is the complex conjugate of the first spreading sequence.
MHz band optional PHY:
The first 8 spreading sequences are cyclic shift of each other, and the last 8 spreading sequences are the complex conjugate of the first 8 spreading sequences.
The SFD sequences are chosen from the spreading sequences.
Submission
BUAA, Vinno

12. Difference 4: Pulse Shaping Filter
: Half-sine filter
To O-QPSK PHY, the zero-to-zero bandwidth is 1.5MHz.
To C-WPAN PHY, the zero-to-zero bandwidth is 3MHz.
C-WPAN: Raised cosine filter
The chip duration is 1us.
The zero-to-zero bandwidth is 1.5MHz.
Submission
BUAA, Vinno

13. Difference 5: Synchronization Performance
In AWGN channel, basic sliding correlation algorithm is used.
Submission
BUAA, Vinno

14. Difference 5: System Packet Error Performance
In AWGN channel, ideal synchronization, 32 data octets in each packet.
Submission
BUAA, Vinno

15. Thank you!
Submission
BUAA, Vinno

16. Backup Slides
Submission
BUAA, Vinno

17. C-WPAN System Performance in Multipath Channel
Tapped-Delay-Line Channel Model
IEEE P Working Group for WPANs, Multipath Simulation Models for Sub-GHz PHY Evaluation, b, Oct
Power delay profile is exponentially declined.
Each path is independently Rayleigh fading.
The average power of the channel response over many packets is 1, but in each packet the power is varied.
Short Delay Environments
Without rake receiver
Long Delay Environments
With 3-tap rake receiver
Submission
BUAA, Vinno

18. C-WPAN System Performance in Multipath Channel
Test Conditions
RMS delay spread 0~600ns
Tx nonlinear amplifier, Rapp’s model, p=3, backoff=1.5dB
Tx and Rx frequency offset ±80ppm, phase noise
Tx and Rx IQ imbalance 2dB, 10o
3bit AD sampling, 8bit baseband processing
Rx will implement time and frequency synchronization and data detection
5000 packets are tested for each SNR, each packet comprises 20 octets
The packet error rate is counted for 90% coverage
Submission
BUAA, Vinno

19. PER in Short Delay Environments without Rake Receiver
Submission
BUAA, Vinno

20. PER in Long Delay Environments with 3-tap Rake Receiver
Submission
BUAA, Vinno