Presented By:

S. M. Riazul Islam 리아즈 STD ID: 82081029

Joint NBI Detection and CE for WB-OFDM

Project Program-2: Wireless Broadband Access

Presentation # 02

Presented in the Class of

Professor Kyung Sup Kwak

Graduate School of Information Technology and Telecommunications

Inha University, South Korea

May 12, 2010

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Contents Introduction

System Model Signal Flow Channel

System Components NBI Detection Channel Estimation Joint Iterative Processing

Simulation Results Comments Reference

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Introduction Coexisting NBI Much higher power concentration in isolated subcarrier than that of OFDM sym. Moreover, Leakage effects.

INTF detection: sensing/void channel before Tx Data aided detection: harmed by OFDM symbol and channel variation

Multistage approach is proposed: combination of NBI and CE

NBI is pre-detected and afterwards CE Based on LMMSE Channel fluctuations can be subtracted from the Rx signal (Noise

and INTF)

System Model: Signal Flow

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System Model: Channel

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Channel c is Gaussian with exp PDP of (v+1) channel taps h=DFTk(c)

The discrete length of the channel results

Tap power coefficients: PDP matrix

Sim: The discrete time CIR is truncataed (5% power)

System Model: INTF

IEEE 802.15.3a: in-band tone interference consists of a simple unmodulated carrier at freq ∆fi

NBI power leackage

Maximum magnitude:

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System Components: NBI Detection Subcarrier with maximum power

This power is compared to a threshold to be determined

Respective sub-carriers and surroundings ones are then signaled to CE together with estimate of the INTF power in that sub-car

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System Components: CE

LMMSE

Auto-correlation matrix

No temporal channel variation and PDP

Estimate of INTF corr

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System Components: Joitn Iterative Processing

Remodulated preamble based on CE is subtracted from the Rx signal: new set of detected INTF

Kmax is recomputed

Resulting sub-carrier power is once again compared with threshold.

With new set and parameters CE is done.

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Simulation Results

Single NBI at SIR=13.25dB, SNR=3dB Three NBI: SIR=6.5dB, SNR=3dB

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Comments

Joint NBI detection and Channel Estimation Improved BER for high SIR (>10dB), if compared to single stage algo

?? Looking for improved channel Estimation technique

Apply Subspace-based NBI followed by Windowing technique Use of OLA principle during NBI detection Use of ICI mitigation filter

Thanks for your cooperation

Questions/Comments

Reference

N. Hadaschik, I. Zakia, G. Ascheid and H. Meyr, “Joint Narrowband Interference Detection and Channel Estimation for wideband OFDM”, In Proceedings of the European Wireless Conference, April 2007.

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