1. May 2007
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: OFDM PHY Proposal
Date Submitted: 7 May 07
Source: Stan Skafidas Company: NICTA
Address Building 193, University of Melbourne
Melbourne, VIC, 3010, Australia
Voice: FAX: none,
Re: OFDM proposal with emphasis on recommendations to the long-preamble structure
Purpose: This is a discussion only document. No action is recommended.
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
Stan Skafidas, Tim Walsh

2. Stan Skafidas, Tim Walsh E-m: {stan.skafidas, tim.walsh} @nicta.com.au
May 2007
OFDM PHY Proposal
Stan Skafidas, Tim Walsh
E-m: {stan.skafidas, tim.walsh}
@nicta.com.au
7th May 2007
Stan Skafidas, Tim Walsh

3. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
May 2007
Introduction
NICTA is proposing an OFDM based solution for the IEEE c PHY.
A modified long-preamble is proposed. This long-preamble structure, and corresponding FDEQ reduces ICI effects.
NICTA are open to mergers and are currently considering a possible merger with COMPA
Stan Skafidas, Tim Walsh
<author>, <company>

4. Long Preamble Structure
<month year>
doc.: IEEE <doc#>
May 2007
Long Preamble Structure GI
IFFT
OFDM Symbol 1
OFDM Symbol 2
Symbol 1 is randomly generated QPSK constellation
Symbol 2 generated from Symbol 1, however, every odd subcarrier is negated.
Stan Skafidas, Tim Walsh
<author>, <company>

5. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
May 2007
Channel Estimation
Standard Channel estimation
Based on a long preamble is corrupted by ICI sources such as IQ mismatch.
Additional processing is required to remove IQ mismatch from channel model.
Nothing is currently done to reduce phase noise from channel model.
NICTA channel estimation
Using suggested long preamble, can reduce phase noise and IQ mismatch effects from channel model without extra computation
Stan Skafidas, Tim Walsh
<author>, <company>

6. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
May 2007
Channel Estimation
Standard Channel estimation
NICTA Channel estimation
Stan Skafidas, Tim Walsh
<author>, <company>

7. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
May 2007
Results
2 scenarios to compare
Compare NICTA preamble & FDEQ, to EXISTING preamble & FDEQ.
Compare NICTA preamble & FDEQ, with NICTA preamble and averaging for FDEQ
We will demonstrate that our method provides significant benefits over scenario 1, in addition to providing some benefit over scenario 2.
Stan Skafidas, Tim Walsh
<author>, <company>

8. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
May 2007
Scenario 1 - Results
IQ gain mismatch 3dB, phase mismatch 10o.
IQ mismatch eliminated from channel model
Stan Skafidas, Tim Walsh
<author>, <company>

9. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
May 2007
Scenario 1 - Results
IQ Phase Mismatch, no correction, FDEQ only
NICTA preamble approx 1.5dB better
Stan Skafidas, Tim Walsh
<author>, <company>

10. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
May 2007
Scenario 1 - Results
IQ Gain mismatch, no correction, FDEQ only
NICTA Preamble approx 3dB improvement
Stan Skafidas, Tim Walsh
<author>, <company>

11. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
May 2007
Scenario 2 - Results
Demonstrates that NICTA method is actively reducing ICI from channel estimate
Stan Skafidas, Tim Walsh
<author>, <company>

12. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
May 2007
Conclusion
Proposed NICTA preamble and corresponding FDEQ reduces the error in the channel model due to phase noise and all but eliminates IQ mismatch from both transmitter and receiver.
In the event that OFDM is selected as the modulation format, we recommend that the given preamble structure be adopted.
Stan Skafidas, Tim Walsh
<author>, <company>