| As the development tendency of communications, wireless communications has become an important sign of the social development. The future communication systems are expected to satisfy higher requirement. It needs to offer not only high quality voice operation, but also high data rate and multimedia services.Multiple input multiple output (MIMO) technique as a great breakthrough for wireless communication systems can enhance the capacity and improve the performance. MIMO-related topics have become a considerable part of today's academic research. However, the employment of multiple antennas at transmit/receive end increases the additional hardware and thus the cost required in the form of radio frequency (RF) chains. To overcome these problems, while utilizing the advantages of multiple antennas, the technique of antenna selection has been developed.Presently, the research on single-user MIMO techniques has been maturational. Multi-user MIMO systems with one base station and many mobile stations have attracted the research attention, since no extra time slots and frequency resources are needed to support more users. It can achieve higher channel capacity compared with single-user systems. How to optimize the assignment of system resources without increasing the consumption of transmission power and sacrificing the bandwidth, and how to fulfill the quality of service (QoS) of different users in a multi-user system are the practical problems to be solved.Multiuser diversity is an inherent diversity form in multiuser wireless communication systems. Different users experience different channel fading. When one user is in deep fading, others may have good channel condition. Based on this observation, the system performance can be improved by exploiting multiuer diversity. Through spatial multiplexing, multiple users can be supported simultaneously. However, the number of simultaneously supportable users is limited by the number of transmit and receive antennas. Generally, in order to ensure capacity performance or to satisfy QoS requirement (SINR, fairness etc.), scheduling is required to manage the users' access to the resources.In this dissertation, receive antenna selection algorithm in single user MIMO systems is studied. For multi-user MIMO systems, in case of single or multiple receive antennas at mobile terminals respectively, corresponding solutions for user selection are proposed. In general, this dissertation mainly discusses as follows:(1) A simple antenna selection algorithm at the receiver is proposed. This algorithm is based on matrix decomposition. It achieves almost the same outage capacity as optimal selection method while with lower computational complexity.(2) Propose an efficient user selection algorithm aiming to maximize the sum rate capacity for multi-user MISO downlink systems. Based on this method, a fair scheduling scheme is further given to ensure fair service to all users in the system. Users with poor channel condition can also be served while keeping relatively high data rate.(3) By considering multi-user MIMO downlink systems, we give an upper bound of sum-rate capacity, and then propose a suboptimal adaptive user selection algorithm. Regard current capacity and the upper bound as the adaptive criterions. The performance of the proposed algorithm is near to the optimal method in different SNRs and with different number of users.In sum, antenna selection methods for MIMO systems and user selection method with scheduling technique for multi-user MIMO systems are investigated in this dissertation. Finally, the problems to be solved in this research field and future research topics are summarized. |
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