Time Domain Channel Shortening for Multicarrier Systems

Multi-Carrier (MC) modulation has various advantages that make it useful for a wide variety of digital communication systems. Actually, it has been chosen as the physical layer standard for a diversity of basic systems such as digital transmission over telephone lines, applications in broadcasting and in wireless networks. The most important advantage of the MC system is its robustness against interferences. In fact, the cyclic prefix (CP) insertion through MC symbols provides higher immunity against delay spread and interferences. Therefore, as long as channel dispersion is not longer than the CP, system performance does not degrade and the need of time-domain equalization is not usually immediate. However, highly time dispersive channel leads to a significant reduction of the transmission data rate since the received signal is corrupted by both inter-carrier and inter symbol interferences. To avoid such a performance degradation, a channel shortening technique, commonly referred to as time-domain equalizer (TEQ is introduced at the receiver front-end. This thesis proposes to develop a new and accurate implements to accomplish perfect time-domain equalization. The present dissertation has three thrusts: The first purpose is to derive a new implementation of the existing adaptive TEQs based on lattice structure. The aforementioned implementation is specifically developed to perform shortening to recursive channels. Then, admitting that the crucial challenge in designing the MC equalizer is to combine channel bit rate optimization into the TEQ design elaboration, we aim to design a TEQ methods to optimize MC channel bit rate. This includes the development of a new and exact model of the subchannel Signal to Interference and Noise Ratio (SINR). The third goal is to propose and analyze blind adaptive algorithms for designing the TEQ in the context of single-input multiple-output channel model.