The Family of LML Detectors and the Family of LAS Detectors for Massive MIMO Communications

The family of local maximum likelihood (LML) detectors and the family of likelihood ascent search (LAS) detectors are successfully applied to symbol detection in massive multi-input multi-output (MIMO) communications and demonstrate performance approaching the NP-hard global maximum likelihood (GML) detector. The LML and LAS detectors in the two families are akin to each other and possess common properties significant in both theory and practical MIMO communications. This book chapter reviews the LML and LAS detectors in a unified framework. The focus is on their formulation, relationships, properties, and GML performance in bit error rate (BER) and spectral efficiency in large MIMO channels.