Maximum Likelihood Parallel Decoding Metrics for Quasi-Orthogonal Space-Time Block Codes: Derivation and Lowpower Implementation

摘要

Orthogonal Space-Time Block Codes (STBCs), of which the Alamouti Code is the best known, allow parallel maximum-likelihood (ML) decoding and full diversity. Yet rate-one, orthogonal designs for complex-valued constellations only exist for two-antenna transmitters. Quasi-Orthogonal Space-Time Block Codes overcome this limitation. These codes allow more than two transmit antennas, provide rate-one codes, and can produce full diversity. QOSTBCs are therefore suitable for multi-antenna base-stations serving single-antenna mobile terminals. This paper describes the derivation and low-power digital implementation of parallel metrics for ML decoding of QOSTBCs.