1. Date Submitted: [March, 2007 ]
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [The PHY Layer Tech Proposal from Chinese WPAN Group ]
Date Submitted: [March, 2007 ]
Source: [Liang Li , Chenyang Yang, Yafei Tian]
Company: [Beihang University (BUAA), Vinno Technologies Inc]
Address: [ Beijing, China ]
Voice:[ ], ,
Re: [ ]
Abstract: [The formal PHY tech proposal from 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
Liang Li

2. Outline
One formal PHY tech proposal from Chinese companies, universities and partners.
Major tech points are upgraded from the OQPSK Modulation on IEEE
Spreading sequence
SFD design
Pulse shaping filter
Synchronization and demodulation performance
Submission
Liang Li

3. CWPAN Proposed Use of New Operation Frequency Bands
Fc= 314.3, 314.8, 315.3, (MHz); BW=400kHz
Fc= 430.3, 430.8, 431.3, (MHz); BW=400kHz
Fc= 433.3, 433.8, 434.3, (MHz); BW=400kHz
Fc= 780, 782, 784, 786, 788 (MHz) BW=2MHz
Submission
Liang Li

4. Communication Modulation 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
0.4
0.2
Chirp Sequence
+ MPSK 50
12.5
430
780 2 1
250
62.5
Submission
Liang Li

5. Upgrade from PHY Layer Operation of IEEE802.15.4-2006
The new PHY tech proposal is similar to the OQPSK ones used in IEEE at sub 1GHZ on:
The principal structures of the transmitter and receiver packet structure
Operation procedure of the transceiver
The important parameters for RF parts
Some different techniques are applied in this new PHY proposal.
Submission
Liang Li

6. Reference Design of the Wireless Transceiver based on New PHY tech Proposal
Submission
Liang Li

7. Difference 1: 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
Liang Li

8. Spreading Sequence New Proposal: OQPSK in 15.4-2006 in sub-1GHz :
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.
OQPSK in in sub-1GHz :
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
Liang Li

9. Sliding Correlation Values of the Preamble Sequence
With Sequence in New Proposal
With Sequence in Std
Submission
Liang Li

10. Difference 2: Pre-processing on Transmission
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 inverse 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
Liang Li

11. SFD Design New Proposal : OQPSK in 15.4-2006 in sub-1GHz :
The 16 spreading sequences are cyclic shift of each other.
The SFD sequence is the complex conjugate of the first spreading sequence.
OQPSK in in sub-1GHz :
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
Liang Li

12. Difference 3: Pulse Shaping on Transmission and Spectrum of Transmit Waveform
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
Liang Li

13. New Proposal: Raised cosine filter
Pulse Shaping Filter
: Half-sine filter
To O-QPSK PHY, the zero-to-zero bandwidth is 1.5MHz.
To New PHY proposal, the zero-to-zero bandwidth is 3MHz.
New Proposal: Raised cosine filter
The chip duration is 1us.
The zero-to-zero bandwidth is 1.5MHz.
Submission
Liang Li

14. Synchronization Performance of Preamble
Simulation Conditions:
AWGN channel environment
Chip rate sampling
Basic sliding correlation receiver
Synchronized on other chips means an error
Submission
Liang Li

15. System Packet Error Performance
Simulation Conditions:
AWGN channel environment
Chip rate sampling
Basic sliding correlation receiver
Ideal synchronization
32 data octets in each packet
Submission
Liang Li

16. The Independent Simulation Results from I2R
I2R implements the independent Simulation based on New PHY proposal. The left figure shows its results.
BUAA obtained the Same results in the right picture. And compare with the ones of I2R on same page. Simulation condition are
Packet Length = 20bytes; AWGN channel, Ideal Sync.
Coherent detection: Decision is based on the real parts of the correlation values
Noncoherent detection: Decision is based on the norms of the correlation values
Submission
Liang Li

17. Tapped-Delay-Line Channel Model
System Performance of Receiver based on New Proposal 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
Liang Li

18. System Performance of Rake Receiver based on New Proposal in Multipath Channel
Test Conditions
RMS delay spread 0~600ns
Tx nonlinear amplifier, Rapp’s model, p=3, backoff=1.5dB
Tx to 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
Liang Li

19. PER in Short Delay Environments without Rake Receiver
Submission
Liang Li

20. PER in Long Delay Environments with 3-tap Rake Receiver
Submission
Liang Li

21. Thank you!
Submission
Liang Li