Turbo Space-time Code In The Mimo Wireless Communication System In Applied Research

High speed data transmission with high reliability is the most promising direction for the future wireless communications. In order to guarantee reliable transmission, various efficient error control schemes are essential. A breakthrough in coding was achieved with the invention of Turbo codes. The remarkable codes have given rises to a large interest in coding theory due to the small bit error rate at low SNR close to the Shannon capacity limits. In the development of the next generation mobile communication systems, it is well known that Turbo codes are the way of error correcting codes of high speed .data channel. To improve receiver performance, space diversity in the multi-path environment should normally be employed. MIMO-based Space-Time coding techniques are the key technology for the future wireless mobile communications to increase frequency efficiency and improve performance of systems. This dissertation researched the Turbo Space-Time coding techniques for wireless mobile communications which involved in several aspects, such as Turbo decoding algorithms, the design and analysis of Turbo interleaver, Turbo and code modulation technique, channel capacity of MIMO system, the design criterion of Space-Time Trellis codes and design of component codes, the design of multi-level code modulation concatenated with STBC in OFDM systems over frequency-selective fading channel. The main works and innovations arc as follows:1. In order to calculate the gap between the performances of Turbo codes with theoretic limits, we studied the AWGN and Rayleigh fading channel capacity with two discrete input and continuous output. On the base of maximum a posteriori probability algorithm, we induced the MAP, Log-MAP, Max-Log-MAP and SOVA algorithms available to Turbo codes decoding. At same time we summarized the popular SISO algorithm which is available to decoding of concatenated codes. At fast.' we gave the merits and shortcomings of different decoding algorithms and explained the results by simulations. 2. Based on the SOVA algorithm, we proposed a modified method and gave the detailed structure of the modified algorithm. Then, we studied particularly the merits of the new algorithm by comparing with the complexity of other extant algorithms. At last we testified the results by experiments.3. We found a new design method of Turbo codes interleaver by the analysis of Turbo codes performance bounds. The new interleaver which is modified on the base of Code-Matched interleaver is not only more popular than the original one but better than the original one in performance also. We proposed the algorithm and parameters of the new interleaver based on the analysis of some random interleavers and gave the simulation results.4. On the base of the extant Turbo coded modulation schemes, we proposed a Turbo TCM scheme which is based on non-binary Turbo codes. We gave the encoding and decoding structure and algorithm. At same time we investigated the effects of different set partitioning schemes. At last we got meaningful results: UP is a robust strategy in Turbo TCM scheme.5. On the base of theory of MIMO channel capacity, we induced the criterion of STTC on slow Rayleigh fading channels and fast Rayleigh fading channels. We proposed apredigested non-binary SOVA algorithm by studying the algorithms , performance and criterion of Turbo Space-Time coding. Then we gave some new structure of component codes and verified that the Turbo Space-Time codes which are made up of the new component codes had better performance by simulation results.6. We designed the encoding and decoding structure of multi-level code modulation concatenated with STBC and applied the new codes in OFDM systems over frequency-selective channels. We testified that the new concatenated codes could achieve both coding gain and diversity gain. Especially the MLC-STBC using non-standard MLC/MQAM can get the frequency-band efficiency and have accepted decoding complexity and delay. At last we verified that UP or UP/UP is the best set partitioning scheme in MLC-STBC in OFDM systems.