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May 12, 2010. 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. Presented By: S. M. Riazul Islam 리아즈 STD ID: 82081029. Graduate School of Information Technology and Telecommunications
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May 12, 2010 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 Presented By: S. M. Riazul Islam 리아즈 STD ID: 82081029 Graduate School of Information Technology and Telecommunications Inha University, South Korea
Contents • Introduction • System Model • Signal Flow • Channel • System Components • NBI Detection • Channel Estimation • Joint Iterative Processing • Simulation Results • Comments • Reference Telecommunication Engineering Lab, INHA Univ
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) Telecommunication Engineering Lab, INHA Univ
System Model: Signal Flow 128 1/3 12-10 2 Telecommunication Engineering Lab, INHA Univ
System Model: Channel • 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) Telecommunication Engineering Lab, INHA Univ
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: Telecommunication Engineering Lab, INHA Univ
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 Telecommunication Engineering Lab, INHA Univ
System Components: CE • LMMSE • Auto-correlation matrix • No temporal channel variation and PDP • Estimate of INTF corr Telecommunication Engineering Lab, INHA Univ
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. Telecommunication Engineering Lab, INHA Univ
Simulation Results Single NBI at SIR=13.25dB, SNR=3dB Three NBI: SIR=6.5dB, SNR=3dB Telecommunication Engineering Lab, INHA Univ
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 Telecommunication Engineering Lab, INHA Univ
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. The END Telecommunication Engineering Lab, INHA Univ