Research On Space-Time Coding Methods For MIMO Wireless Communication Systems

The future broadband wireless communication systems are expected to provide ubiquitous, high-reliability, and high-data-rate mobile multimedia transmission. MIMO (Multiple-Input Multiple-Output) technique utilizing multiple antennas to realize multiple transmissions and multiple receiving can exploit space resource adequately and can improve channel capacity without any loss in bandwidth and transmitting power. So it can meet the need of high data transmission in future wireless communications.Recently, the space time codes desinged for the multiple antennas system have inspired many attentions. As a kind of new technique, space-time trellis coding and space-time block coding attracts many investigators and has also adopted by 3GPP standard. However, there are still many technical problems to be solved for the STTC and STBC realization in practical engineering applications, such as STTC designs that can improving transmit diversity gain, both in terms of reducing decoding complexity, and the introduction of coding gain to STBC. In view of the above discussions, this dissertation focuses on several issues of the space-time coding and the corresponding Trellis coding modulation. The main contributions included in this dissertation can be summarized as follow:1. By studying the super-orthogonal space-time coding designs for 2 transmit antennas and super-quasi orthogonal space-time coding designs for 4 transmit antennas, a novel super-orthogonal space-time coding designs for four transmit antennas is proposed. By exploiting the inherent structure association between OSTBC and QOSTBC, the proposed schemes can obtain the full-rate and good performance while keeping the coding complexity as super-orthogonal space-time coding schemes for 2 transmit antennas. Simulations results demonstrate that the proposed schemes can gain the about 2dB performance gain with significant reduction in computational load over the super-quasi orthogonal space-time coding schemes.2. The maximization of data rate under the constraint of diversity gain, coding gain and total transmit power is a considerable issue in concatenated orthogonal space-time coding system. Based on the concatenated orthogonal space-time coding design criterion, this paper proposed a novel full-rate concatenated orthogonal space-time block codes with multiple trellis coded modulation approach. By introducing the power diversity factor, a new combining algorithm for maximum likelihood decoding is derived. Simulation are performed over the fast and the slow Rayleigh fading channels to demonstrate the 1dB coding gain of the proposed concatenated orthogonal space-time block codes with multiple trellis coded modulation schemes over the super orthogonal space-time coding schemes..3. The field of concatenated space-time block coding (inner) with trellis coded modulation (outer) has recently attracted interest as a means of jointly considering the error correction coding gain and diversity gain possible without bandwidth expansion and power expansion over fading channels.In this paper, a concatenated space-time block coding (STBC)with asymmetric MPSK TCM scheme, based on the design criteria for constructing optimal concatenated space-time block coding with TCM. is presented by introducing the new optimal signal point assignment. Analysis and simulation results demonstrate that these concatenated STBC with asymmetric MPSK TCM have better coding gain than traditional concatenated STBC with TCM under the same spectral efficiency, decoding complexity.4. In this paper, the design of space-time codes employing multiple trellis-coded modulation (ST-MTCM) is proposed based on Frobenius norm. In the new ST-MTCM approach, by properly labeling each trellis branch for ST-MTCM with an T×N orthogonal codematrix and then employing Ungerboeck's set partitioning scheme, maximum transmit diversity gain and improved coding gain can be achieved. It is also shown that the scheme does not require different space-time code design criteria for fast fading channels and quasi-static channels. Furthermore, transmitted branch matrix orthogonality is exploited to ease systematic code search procedure. The performance of the proposed codes is demonstrated by simulation results.5. By studying the Trellis Coding Modulation (TCM) and Multi-Trellis Coding Modulation (MTCM), an improved concatenated orthogonal space-time multiple trellis coded modulation approach for different Rayleigh fading channel models is proposed in this paper based on the concatenated orthogonal space-time coding design criterion. Simulation and analysis results show that the coding gain loss of the modified concatenated orthogonal space-time coding approach is only 0.4dB compared with that a previously proposed concatenated orthogonal space-time coding approach but the data rate is 50 percent greater; the modified concatenated orthogonal space-time multiple trellis coded modulation approach producing 2.6dB coding gain over concatenated super orthogonal space-time coding approach.