Presented By: S. M. Riazul Islam STD ID: 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

March 10, 2010 Telecommunication Engineering Lab, INHA Univ 2 Contents Introduction System Model Signal Flow Channel System Components NBI Detection Channel Estimation Joint Iterative Processing Simulation Results Comments Reference

March 10, 2010 Telecommunication Engineering Lab, INHA Univ 3 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 March 10, 2010 Telecommunication Engineering Lab, INHA Univ 4 1/

System Model: Channel March 10, 2010 Telecommunication Engineering Lab, INHA Univ 5 Channel c is Gaussian with exp PDP of (v+1) channel taps h=DFT k (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 a: in-band tone interference consists of a simple unmodulated carrier at freq f i NBI power leackage Maximum magnitude: March 10, 2010 Telecommunication Engineering Lab, INHA Univ 6

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 March 10, 2010 Telecommunication Engineering Lab, INHA Univ 7

System Components: CE LMMSE Auto-correlation matrix No temporal channel variation and PDP Estimate of INTF corr March 10, 2010 Telecommunication Engineering Lab, INHA Univ 8

System Components: Joitn Iterative Processing Remodulated preamble based on CE is subtracted from the Rx signal: new set of detected INTF K max is recomputed Resulting sub-carrier power is once again compared with threshold. With new set and parameters CE is done. March 10, 2010 Telecommunication Engineering Lab, INHA Univ 9

Simulation Results Single NBI at SIR=13.25dB, SNR=3dB Three NBI: SIR=6.5dB, SNR=3dB March 10, 2010 Telecommunication Engineering Lab, INHA Univ 10

March 10, 2010 Telecommunication Engineering Lab, INHA Univ 11 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 March 10, 2010 Telecommunication Engineering Lab, INHA Univ 12