All digital communication channels are subject to inter-symbol interference (ISI). To achieve the desired system performance, at receiver end, the effect of ISI must be compensated and the task of the equalizer is to combat the degrading effects of ISI on the transmission. Due to the demand of high data transmission rate, the multicarrier modulation (MCM) technique implemented with the orthogonal frequency division multiplexing (OFDM) has been adopted in many modern communications systems for block transmission. In block transmission systems, transmitter-included redundancy using finite-impulse response (FIR) filterbanks can be utilized to suppress inter-block-interference (IBI). However, the length of redundancy will affect the system performance, which is highly dependent on the length of channel impulse response. To deal with the effect of ISI, many equalizing schemes have been proposed, among them the FIR zero-forcing (ZF) equalizer with the non-orthogonal projector provides a useful transceiver design structure for suppressing the IBI and ISI, simultaneously. In this thesis, we propose a new equalizing scheme; it combines the FIR-ZF equalizer with non-orthogonal projector as well as the Bayesian decision feedback equalizer (DFE) for IBI and ISI suppression. The Bayesian DFE is known to be one of the best schemes to achieve the desired performance for eliminating ISI. It can be employed to achieve the full potential of symbol-by-symbol equalizer. That is, after removing the effect of IBI with the non-orthogonal projector, the Bayesian DFE is employed for eliminating the ISI, simultaneously. For comparison, the system performance, in term of bit error rate (BER) is investigated, and compared with the minimum mean square error (MMSE)-IBI-DFE. The advantage of the new proposed equalizing scheme is verified via computer simulation under condition of insufficient redundancy.

Orthogonal frequency division multiplexing (OFDM) modulator with redundancy has been adopted in many wireless communication systems for higher data rate transmissions. The introduced redundancy at the transmitter allows us to overcome serious inter-block interference (IBI) problems due to highly dispersive channel. However, the selection of redundancy length will affect the system performance and spectral efficiency, and is highly dependent on the length of channel impulse response. In this thesis, based on the pseudorandom postfix (PRP) OFDM scheme we propose a novel block-based OFDM transceiver framework. Since in the PRP-OFDM system the PRP can be employed for semi-blind channel estimation with order-one statistics of the received signal. Hence, for sufficient redundancy case the PRP-OFDM system with the Bayesian decision feedback equalizer (DFE) is adopted for suppressing the IBI and ISI simultaneously. However, for the insufficient redundancy case (the length of redundancy is less than the order of channel), we first propose a modified scheme for channel estimation. To further reduce the complexity of receiver, the maximum shortening signal-to-noise-ratio time domain equalizer (MSSNR TEQ) with the Bayesian DFE is developed for suppressing the IBI and ISI, separately. That is, after knowing the channel state information (CSI) and removing the effect of IBI with MSSNR TEQ, the Bayesian DFE is applied for eliminating the ISI. Via computer simulation, we verify that performance improvement, in terms of bit error rate (BER), compared with the conventional block-based minimum mean square error (MMSE)-DFE can be achieved.