The technique of multi-carrier (MC) transmission has §received wide spread interest, especially for high §data rate applications. Sometimes, scarcity of §available bandwidth necessitates spectrum sharing §between the MC system and other narrow band systems. §If a part of the spectrum of the MC system is §overlapped by a relatively narrow band transmission §signal, the latter will introduce narrow band §interference to the MC system, hampering the proper §action of the MC system. In such scenarios, the MC §receiver has to perform actions, such as channel §estimation and synchronization, in the presence of §possibly strong in-band interference. In this book, §we study the effect of digitally modulated narrow §band interference signals on some popular §synchronization and channel estimation algorithms §for uncoded and coded MC transmission. We also modify these algorithms to have better performance §in the presence of interfernce. Further, we develop §a new low complexity algorithm to estimate and §suppress interferers located in the MC spectrum.