The Diversity Performance Research Based On Full-rate Space-time Block Codes In Multi-antenna System

In the future civil field, advancement of society and improvement of people's standard of living, new generation wireless communication systems are expected to provide higher transmission rate, offer better quality and support faster moving terminals.The most effect way to meet such requirements is the MIMO technology, which deploys multiple antennas at transmitter and/or receiver. Recent research in information theory has shown that larger gains in the capacity of channels are feasible in MIMO systems. To make full use of the capacity of MIMO channels, space-time coding is a set of practical signal techniques when there is no channel state information (CSI) at the transmitter. Space-time coding introduces the correlations in both time and space domains when signals are transmitted by different antennas, which can greatly enhance the data transmission rate and improve the performance without bandwidth expansion or transmit power augment. This dissertation concentrates on the no-orthogonal space-time codes and antenna selection technology for MIMO systems, and it includes:●QSTBC system for the case of four transmit and one receive antennas was proposed The dissertation generalize these results to 2n transmit and an arbitrary number of receive antennas. Furthermore, the dissertation derives an analytical lower hound for the fraction of outage probability achieved with QSTBC. An upper bound is also proposed, the dissertation derives analytical expressions for the case of four transmitting antennas. Furthermore, by utilizing the special structure of the QSTBC a new transmit strategy is proposed, which decouples the signals transmitted from different antennas in order to detect the symbols separately with a Linear ML-detector rather than joint detection.●Generalize some of their characters and derive several new patterns to enrich the family of quasi-orthogonal STBC. A new lower complexcity QO-STBC decoding algorithm based on CR technology is proposed, which uses group-constrained linear transformation (GCLT) as a mean to optimise the diversity and coding gains of a QO-STBC, Compared with QO-STBC with constellation rotation (CR), QO-STBC with GCLT requires only half the number of symbols for joint detection, hence lower maximumlikelihood decoding complexity.●Low complexity sphere decoding method of decoupled functions is presented. The SD algorithm finds the shortest vector in the sense of Euclidean norm within the sphere, however,the decoupled metric functions in the detection of quasi-orthogonal space-time block codes are not in the required Euclidean norm format. In this letter, the ML metric of quasi-orthogonal space-time block codes is written into two independent Euclidean norms, thus SD can be applied to each function independently.The dessertation presents a sphere decoding algorithm which finds a method of searching new vector in a sphere radius. A new better searching method based on re-ordered vectors in complex field is presentted. This approach optimizes sphere radius iteration, increases the searching speed of signal vector.●Introducing extended orthogonal space-time block codes with four antenna selections, and proposing a MIMO diversity adaptive control method based on pair bits feedback according to EO-STBC characteristic.This method not only realizes a full rate and full diversity, but also improve the MIMO diversity performance through channel state information (CSI) and antenna selection.Adcaned method to simplify 3 antennas system and 4 antennas system to one is used to be available joint detection.