The Research Of Antenna Selection Algorithm In MIMO Systems

Along with the development of the service requirements, Wireless communications have developed from only voice service to multi-media service such as image, video and data. The rich media content leads to demand for high access data rate. High data rate wireless communication, nearing Gbps transmission rates, is of interest in emerging WLAN (Wireless Local Area Networks). Additionally, future home Audio/Visual networks will be required to support multiple high-speed HDTV (High Definition Television), which again demand near Gbps data rates. So high transmission rate is a big challenge to the limited frequency spectral. The research of information theory has demonstrated that MIMO (Multiple-Input-Multiple-Output) system which employs multiple antennas both at the transmit side and the nication systems; also can improve the system performance. So MIMO is very fit for high data service in 3G, 4G wireless communications. Therefore, MIMO has been the key technology for next generation wireless communications.MIMO can provide both multiplex gain and diversity gain. Spatial multiplex gain is regarded as the most important avail of MIMO. Spatial multiplex extend the channel dimensions, and ofer a linear increase scaled to the antenna number for no additional power or bandwidth expenditure, which enlarge frequency spectral efficiency by a long way. Spatial multiplex is achieved by Layered Space-Time Code, such as D-BLAST, V-BLAST and H-BLAST.Diversity technique is a powerful technique to mitigate fading in wireless links. Diversity techniques rely on transmitting the signal over multiple independently fading paths (in time/frequency/space). Spatial (or antenna) diversity is preferred over time/frequency diversity as it does not incur expenditure in transmission time or bandwidth. Diversity improves the transmission reliability and enhances Qos (Quabty of Service). If the M T MR links composing the MIMO channel fade independently and the transmitted signal is suitably constructed, the receiver can combine the arriving signals with considerably reduced amplitude fade in comparison to a SISO link and get M T MR order diversity. Extracting spatial diversity gain in the absence of channel knowledge at the transmitter is possible using suitably designed transmit signals. The corresponding technique is known as spacetime code. STBC and STTC are the most famous code until now.The hot topic of MIMO include informationt heory and code design, antenna subset selection, antenna design and channel modeling, MIMO-OFDM, precode, multi-user MIMO and so on. This paper mainly focuses on MIMO antenna subset selection algorithm and blind adaptive algorithm of Orthogonal Space-Time Block Coded MIMO system. This paper is mainly on the research on antenna subset selection in the MIMO system.In this paper, the author firstly analyzes a few time-space encoding scheme which have effect on the performance of the MIMO system studied and compared such as STBC, STTC, BLAST, and present the simulation result of it. Secondly, MRC and SC are discussed, and its performance is simulated. Antenna selection for spatial multiplexing system with ZF may reduce complexity is discussed. The diversity gains of the MIMO with antenna selction is the same to the MIMO in the specifical condition, and result of the transmit diversity and receive diversity is given by simulation. Finally, we study the antenna selection because it can effectively reduce the cost and complexity of the MIMO system. In this part, a fast algorithm of receive antenna selection based on loss minimization and incremental selection and decremental selection, which chooses two antennas one time replace that one, its advantage is demonstrated from capacity view. Simulation results show that our algorithm has near-optimal performance, while its complexity is far lower than the optimal algorithm.