Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE P802.15 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: +61 3 8344 8407 FAX: none, E-Mail: stan.skafidas@nicta.com.au 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 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. Stan Skafidas, Tim Walsh

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

3. Introduction • NICTA is proposing an OFDM based solution for the IEEE 802.15.3c 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

4. Long Preamble Structure • Symbol 1 is randomly generated QPSK constellation • Symbol 2 generated from Symbol 1, however, every odd subcarrier is negated. IFFT GI OFDM Symbol 1 OFDM Symbol 2 Stan Skafidas, Tim Walsh

5. Channel Estimation Standard Channel estimation • Based on 802.11a 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

6. Channel Estimation • Standard Channel estimation • NICTA Channel estimation Stan Skafidas, Tim Walsh

7. 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. Results Stan Skafidas, Tim Walsh

8. IQ gain mismatch 3dB, phase mismatch 10o. Scenario 1 - Results • IQ mismatch eliminated from channel model Stan Skafidas, Tim Walsh

9. IQ Phase Mismatch, no correction, FDEQ only Scenario 1 - Results • NICTA preamble approx 1.5dB better Stan Skafidas, Tim Walsh

10. IQ Gain mismatch, no correction, FDEQ only Scenario 1 - Results • NICTA Preamble approx 3dB improvement Stan Skafidas, Tim Walsh

11. Scenario 2 - Results • Demonstrates that NICTA method is actively reducing ICI from channel estimate Stan Skafidas, Tim Walsh

12. 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