Research On MIMO Channel Modeling And Multiple-antenna Designing For New Generation Wireless Communication Systems

The third-generation mobile communication (3G) technologies are still expected very much to be improved, however, the new generation wireless communication technologies are emerging and booming, whose target of providing ubiquitous, high quality, and high data rate mobile multimedia transmission sounds much attractive. Of course, the implementation of this unprecedented target is not so easy, and the traditional communication systems using single-antenna transmitting and receiving are confronted with a stiff challenge to achieve this target. The demands of both high capacity and high reliability in the new generation wireless communication systems are not enough to be met even though one of the traditional improved measures, such as the traditional transmit diversity, receive diversity and smart antenna technology, is used. Fortunately, the creative technology, namely Multiple-Input Multiple-Output (MIMO), has provided a novel solution to this problem. MIMO methods make use of multiple-antenna at both the transmit and the receive side of the radio link to multiply the capacity and reliability over more traditional wireless communication systems by fully exploring the space resource within the same frequency band at no additional power expenditure. However, many more problems are emerging and urgently wanted to be solved in MIMO communication systems due to introducing the multiple-antenna comparing with the traditional single-antenna systems.This dissertation, sponsored by the project of the Novel types of antennas and diversity technology which is one part of the National High Technology Research and Development Program (863 program), focuses on the MIMO channel modeling and multiple-antenna designing for new generation wireless communication systems, and is concerned with the systematic and thorough researches on many aspects, such as MIMO channel modeling, signal correlation analysis in MIMO channel, effects of multiple-antenna on the performance of MIMO channel, the design of multiple-antenna andanalysis of MIMO experimental data. These researches provide powerful guarantee for precise analysis and design both of space-time coding/decoding and modulation/demodulation, and establish a solid theoretical basis for the correlaton evaluations of fading signals, as well as provide both important insights into MIMO antenna design and novel design ideas.The major contributions in this dissertation include four levels.The first level is mainly concerned with the systematic analysis of the signal correlation in MIMO channels. The research on the effects of signal correlation on the performance of MIMO channels establishes the solid theoretical basis both for MIMO channel modeling and MIMO antenna designing, and provide important insights into the analyses of capacity and Bit-Error-Ratio (BER) of MIMO channels. First, the general analytical expressions are obtained for the spatial correlation (SC) between antennas including the antennas properties (such as radiation patterns, antenna spacing, antenna mutual coupling (AMC)), signal and environment properties such as angles of arrival (AOAs), the angular spread (AS) of the scattering signals; the detailed analytical expressions for the SC under various power azimuth spectrum (PAS) distributions (such as uniform, cosine, Gaussian, Laplacian) are further derived. Secondly, the analytical solutions for BER performance for two-branch diversity reception and Maximal-Ratio Combining (MRC) in correlated Rayleigh fading are obtained, with which it is convenient to examine the effects of the fading correlation on the diversity performance. Thirdly, the performance loss due to correlation in V-BLAST is quantified in forms of the analytical upper bound of the average probability of error (APE), and it is found that the correlations at both ends of the wireless link can be incorporated equivalently into only those at the transmit end, which shows the losses essentially reduce the effective signal-to-noise ratio (SNR) of the data substreams. As a result, an idea is obtained for systematic design of wireless link: the high correlation at the receive end canbe compensated for to a certain degree by reducing the correlation at the transmit end.In the second level, the systematic researches on MIMO channel modeling and the effects of multiple-antenna on the performances of MIMO channel are achieved. First of all, the number of the effective scatterers in propagation environment is modeled as a birth and death process, and then a dynamic MIMO wireless channel model is proposed to investigate the effects of mobility both of scatterers and transceiver antennas on the SC and capacity of MIMO channels, and hence it remedies the deficiency in previous investigations. Next, based on the engineering practical applications and focused on the performances of multiple-antenna, the effects of many aspects such as antenna array orientation, AMC and the channel coupling (CC) between receiver passages, on the performance of MIMO channels are investigated, which establish the solid theoretical basis for the MIMO antenna design. In the research of the impact of antenna array arrangement (orientation) on the performance of MIMO wireless channels, it is obtained that the transmit and receive antenna array should be rotated to make their norm point to the mean direction of arrival (DOA) and departure (DOD) to attain higher capacity, respectively. It is found that the orientation of the array with smaller AS dominates the impact, and that increasing the AS diminishes and even eliminates the impact. In the research of the effects of AMC on the performance of MIMO wireless channels, the general coupling matrix is drived, and the analytical expressions for both the mean received power of each antenna and the SC between antennas in the presence of AMC are also provided. The effects both of the AMC and mean DOA on both the SC and capacity of MIMO channels are analyzed. Both the conditions under which AMC has no effect on the SC and under which there is no power difference are identified, respectively. It is found that under certain conditions AMC has a beneficial decorrelation effect to improve channel capacity. In the research of CC in in a two-branch antenna polarization diversity system by applying a network theory framework, the impacts of CC on both the correlation between diversity branches and the mean power difference therein are analyzed, and it is obtained that thecorrelation increases but the mean power difference may decrease due to CC, and hence it is found that under certain conditions the CC can improve diversity performance. Finally, an equivalent relation of CC is proposed, which explains CC from the point of view of antennas and states that the CC is equivalent to each antenna deviating a complex angle from its orginal position. This equivalent relation bridges CC and the deviation angles of antennas, and helps to analyzing and correcting CC.The third level is mainly concerned with the MIMO antenna design, which is the engineering implementation according to the design rules provided by the theoretical analyses. First of all, through reviewing the existing MIMO antenna design schemes and deeply analyzing the MIMO antenna design, the basic technical requirements for MIMO antennas are obtained and the properties of MIMO antennas are also summarized. The author, cooperating with others, proposes many kinds of MIMO antenna schemes, such as one scheme for basestation antennas, one for terminal antennas and one for handset antennas, and provides each design instance, which has novel design ideas and shows excellent performance. These novel types of antenna designs not only bring progress in antenna design techniques, but also advance development in MIMO communication technology.The last level focuses on the analyses of MIMO experimental data to validate the theoretical researches and to provide information both for improving MIMO channel modeling and optimizing antenna designing. A large numbers of measurement campaigns are performed using the MIMO measurement platform developed by the author and others in indoor and outdoor environments. Some experimental results are provided, i.e., the distribution of the MIMO channel coefficients, the distributions both of the eigenvalues of the channel correlation matrix and channel capacity, the SC of channels, and the BER performance of the MIMO channel transmission, etc. The experimental phenomena and results are analyzed in detail, and hence many important conclusions are obtained, which are helpful to thoroughly...