Research On MIMO Antenna Selection Systems With Reconfigurable Radiation Patterns

Future wireless communication systems require higher transmission rates, security, intelligence, flexibility and better transmission quality. To meet this requirement, the following key technologies will be used: smart antenna, software radio, Multiple-Input Multiple-Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM). MIMO can improve the quality of wireless communications and data rate largely without increasing bandwidth and transmission power. To reduce the cost, we study the antenna selection technique, which gets close to the original system performance by using less RF links. As miniaturization of wireless terminal can not be allowed to use multiple antennas, we introduce pattern reconfiguration to MIMO antenna selection system, which can further reduce cost and get better performance.Based on the analysis of several typical MIMO antenna selection algorithms, a low complexity limited adaptive Markov Chain Monte Carlo selection algorithm is proposed. And with the combination of pattern reconfigurable ability of antenna and MIMO antenna selection system, we propose an antenna selection algorithm based on the state of radiation pattern of reconfigurable antennas. The algorithm is based on the fact that the radiation states of the reconfigurable antennas are corresponding to the channel states and optimizing radiation state is to maximize the Frobenius norm of the channel matrix. According to the relationship between SNR and channel matrix, we find that the SNR of the receiver is the highest now, that is, the performance of the system is improved. Theoretical research and simulation results show that, compared with the traditional MIMO system, reconfigurable MIMO system can obtain more array gain and ergodic capacity, which are increasing with the number of the radiation states of each antenna.