A Review of Space time trellis codes with ideal beamforming for quasi-static Rayleigh fading channel

I. Introduction Multiple-input and multiple-output (MIMO), uses multiple antennas at both the transmitter and receiver to improve communication performance. MIMO technology has involved consideration in wireless communications, as it offers major increase in data throughput and link range without further bandwidth or increased transmit power. It attains this goal by distributing the same total transmit power over the antennas to achieve an array gain that improves the spectral efficiency (more bits per second per hertz of bandwidth) or to achieve a diversity gain that improves the link reliability (reduced fading). MIMO schemes that assume the channel knowledge is only available at the receiver enhances a lot of research interest in this field [1]. MIMO modulation schemes with channel knowledge at receiver only are generally of two types, spatial multiplexing systems and diversity systems. Spatial multiplexing or Bell Labs Layered Space Time (BLAST) type systems [2], on the other hand, transmit independent data streams from each transmitting antenna, permitting spectral efficiency to be attained at the cost of a loss in diversity advantage for a fixed number of receive antennas. Diversity modulation, or space-time coding [3], uses codewords designed to maximize the diversity advantage of the transmitted information. Such codes incline to maximize diversity gain at the expense of some loss in available capacity. The space-time coding work initiated with paper by Winters [4], which proposes a system using transmit diversity and coding techniques, followed by the innovative paper by Tarokh, Seshadri and Calderbank in 1998 [5] in which they stated the essential theory of space-time coding and lead the first true space-time codes, namely space-time trellis codes (STTCs). This paper was followed by Alamouti's paper [6], which managed to the improvement of space-time block codes (STBCs).The original BLAST structure was developed by Foschini [7] which uses a multi-element antenna array at both the transmitter and receiver, where every antenna transmits an independent sub stream of data.