By Songping Wu
Time: 11:40 AM-01:00 PM, Monday, April 26, 2004.
Place: Room 202, ECE Center, New Jersey Institute of Technology (NJIT), Newark, NJ.

Orthogonal frequency division multiplexing (OFDM) is a promising technique which has high spectrum efficiency and the robustness against channel frequency selectivity. One drawback of OFDM is its sensitivity to phase noise. It has been shown that even small phase noise leads to significant performance loss of OFDM. Therefore, we present the analysis of phase noise effects on OFDM systems and the corresponding solutions.

Motivated by what have been proposed in the literature, we derive exact signal to interference plus noise ratio (SINR) for arbitrary phase noise levels. Furthermore, in a multiple access environment with multiple phase noise, we provide closed form of bit error rate (BER) performance as a function of phase noise parameters.

Due to the detrimental effects of phase noise on OFDM, phase noise mitigation is quite necessary. Several schemes are proposed to mitigate both single and multiple phase noise. It is shown that the proposed schemes have the performance close to no-phase-noise case while outperforming conventional methods. We further present two general approaches which extend conventional schemes in the literature and take them as special cases. Different implementation techniques are also specified. Moreover, analytical and numerical results are provided to compare the performance of these approaches.

Similar to OFDM, an OFDM system with multiple antennas, i.e., Multiple Input Multiple Output (MIMO)-OFDM, also cause severe performance degradation due to phase noise, and what have been proposed in the literature may not be applicable to MIMO-OFDM. Therefore, a new scheme is proposed to mitigate phase noise for MIMO-OFDM, and it provides significant performance gains over systems without phase noise mitigation. Furthermore, this scheme acheives adequate performance with high spectrum efficiency, and also provides a very simple structure, which makes it very attractive for practical implementations.

Advisor: Yeheskel Bar-Ness, Distinguished Professor, NJIT

Committee members:

Ali Abdi, Assistant Professor, NJIT

Alexander M Haimovich, Professor, NJIT

Elisa Michalopoulou, Associate Professor, NJIT

Ravi Narasimhan, Assistant Professor, Standford University