Performance Evaluation of an Antenna Selection MIMO System with RF Switches in Mobile Terminals

Performance of a multiple input/multiple output (MIMO) system is largely degraded when it is equipped in mobile terminals or placed near a human body because radio waves are absorbed or shielded by the human body. This paper evaluates an antenna selection-based MIMO system under environments near human body. Each MIMO antenna branch at the receiver of the proposed MIMO system is equipped with several antennas, which have different characteristics such as polarizations and directional patterns, and the receiver selects one of them by radio frequency (RF) switches. A 2times2 MIMO propagation measurement at an indoor environment with the proposed antenna is conducted, and channel capacities and bit error rates (BERs) are evaluated by computer simulations with the measured channel data. From the results, the channel capacity is improved by more than 1.5 bit/sec/Hz when the proposed antenna is used near a human body. In addition, from the BER simulations that assume OFDM transmission IEEE802.11n, it is found that the received power is improved by more than 5 dB at cumulative distribution function (CDF) value of 0.5.