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

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

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Project ieee p802 15 working group for wireless personal area networks wpans 3656295

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: [email protected]

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


Ofdm phy proposal

OFDM PHY Proposal

Stan Skafidas, Tim Walsh

E-m: {stan.skafidas, tim.walsh}

@nicta.com.au

7th May 2007

Stan Skafidas, Tim Walsh


Introduction

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


Long preamble structure

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


Channel estimation

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


Channel estimation1

Channel Estimation

  • Standard Channel estimation

  • NICTA Channel estimation

Stan Skafidas, Tim Walsh


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.

Results

Stan Skafidas, Tim Walsh


Scenario 1 results

IQ gain mismatch 3dB, phase mismatch 10o.

Scenario 1 - Results

  • IQ mismatch eliminated from channel model

Stan Skafidas, Tim Walsh


Scenario 1 results1

IQ Phase Mismatch, no correction, FDEQ only

Scenario 1 - Results

  • NICTA preamble approx 1.5dB better

Stan Skafidas, Tim Walsh


Scenario 1 results2

IQ Gain mismatch, no correction, FDEQ only

Scenario 1 - Results

  • NICTA Preamble approx 3dB improvement

Stan Skafidas, Tim Walsh


Scenario 2 results

Scenario 2 - Results

  • Demonstrates that NICTA method is actively reducing ICI from channel estimate

Stan Skafidas, Tim Walsh


Conclusion

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


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