Ici Mitigation. Multi-carrier Wireless Communication Systems Technology Research And Simulation

Multicarrier communication technology, such as OFDM (Orthogonal Frequency Division Multiplexing), has been chosen as the major candidate technique for the future wireless communication systems. Among the multicarrier systems, OFDMA (Orthogonal Frequency Division Multiple Access) and DFT-S-OFDMA (Discrete Fourier Transform Spread OFDMA) have been adopted as the access technologies for 802.16e WiMAX, 3GPP LTE (Long Term Evolution) respectively.However, multicarrier communication system is very sensitive to CFO (Carrier Frequency Offset), especially in the uplink of multiuser wireless communication system, different users have different CFOs, the ICI (Inter-Carrier Interference) caused by multiple independent CFOs is very serious, and efficient signal processing technology has to be designed to suppress the ICI; on the other hand, due to the effect of high Doppler spread, the channel is time-selective during one multicarrier symbol in the high-speed mobile wireless communication channel, causing serious ICI.This dissertation studies the ICI suppression technology in the multicarrier communication system:Chapter 1 introduces the fundamental principle of multicarrier communication system, shows the importance of ICI suppression, and points out the main study contents of this dissertation.Chapter 2 analyzes the multicarrier system's SIR (Signal to Interference Ratio) in the presence of multiple CFOs, and summarizes the typical existing methods of suppressing ICI.Chapter 3 studies the ICI suppression technology in the uplink of multicarrier system. Firstly, a novel CFO compensation method for the OFDMA, which maximizes the SIR, is proposed; secondly, the MMSE (Minimum Mean Square Error) equalizer, which considers the residual ICI after the optimum CFO compensation as a part of AWGN (Additive White Gaussian Noise), is used to suppress ICI; lastly, the validity of proposed method is shown. Chapter 4 studies the ICI suppression technology in the multi-antenna multicarrier system. Firstly, the SIR in the presence of multiple CFOs is analyzed; secondly, the CFOs are compensated based on the maximization of SIR, and the MMSE equalizer is used, considering the residual ICI as a part of AWGN; lastly, the validity of proposed method is shown.Chapter 5 studies the ICI suppression technology of multicarrier communication system in the high-speed mobile channel, summarizes the mathematical models, fundamental principle and complexity of various algorithms, and simulates the BER performance to provide theoretical basis for the system design.Chapter 6 summarizes the whole dissertation, and investigates the possible future directions in the study of ICI suppression technology in multicarrier communication system.