The mobile communication systems has been growing fast and continuously over the past two decades.Therefore, in order to fulfill the demand for this repaid growth, the standardization bodies along with wireless researchers and mobile operators around the world have been constantly working on new technical specifications. An important problem in modern communication is known as NP-Complete problem in ML Detection of signals transmitting over MIMO channel of the OFDM system. Development of the Sphere Decoder as a result of the rapid advancement in signal processing techniques provides ML detection for MIMO channels.This book focuses on the OFDM transceiver system including SNR loss compensation for different QAM modulations and takes a good look at the near optimal algorithm for sphere detection based on Schnorr-Euchner by ML method of a vector of symbols transmitted over MIMO channel. The analysis and algorithms are general in nature. The book is based on 4th generation mobile communication environment and should be especially useful to professionals as well as students or anyone else who are interested in wireless Communications fields.