Minimal transmit redundancy FIR precoder-equalizer systems design

Overcoming frequency selective fading effect in wireless channels has become a major obstacle in designing high performance broadband wireless communication systems. This has motivated many transceiver designers to come up with different techniques to combat against such adverse effects without significantly increasing bandwidth consumption as well as system complexity.; In this dissertation, a set of low complexity and bandwidth efficient block based FIR precoder-equalizer systems is proposed for tackling the selective fading problem. Due to the spectral nulling effect of selective fading channels, some frequency components of the transmitted signal will be eliminated by the channel, thereby hindering signal reception. In order to perfectly recover the source signal at the receiver side, redundant information is required to be introduced into the transmitted signal. The redundancy insertion can be done via a precoder at the transmitter. However, the inserted redundant signal will consume additional channel bandwidth such that the transmission efficiency will be reduced. In this thesis, our goal is to design a minimal redundancy precoder-equalizer system to avoid the fading channel problem so that the transmission efficiency is maximized. The system requirement and the amount of redundancy required for the existence of FIR zero-forcing precoder-equalizer are investigated. A systematic design method and design criteria for the precoder and equalizer using nonmaximally decimated filterbank are proposed. These design methods and system requirements are further extended to that of FIR zero-forcing precoder-equalizer system over MIMO frequency selective fading channels. With the proposed precoder and equalizer design methods, an iterative algorithm that jointly optimizes the performance of both the precoder and the equalizer is proposed. Apart from the zero-forcing equalization, the design method for the FIR equalizer that achieves minimum mean squared equalization is also proposed. Finally, a group based successive interference cancellation technique is proposed to further improve the performance of the FIR zero-forcing equalizer and that of the minimum mean squared error equalizer. Numerical results and comparisons with various schemes in literature are provided to demonstrate the potential of our proposed techniques.