On Energy Efficient Transceivers Equipped with a Compact Antenna Array

The issue of improving energy efficiency for sizelimited transceivers is considered. Effective transmitter-end and receiver-end coupling matrices are studied. Different from prior works, effective radiation impedances are involved in the expression of effective transmitter-end coupling matrix (ETCM). It is proved that, when transmit antennas are coupled, effective radiation impedances vary with input signals and thus so does ETCM, whereas effective receiver-end coupling matrix (ERCM) does not vary with incident waves even when receive antennas are coupled. Based on the analysis on ETCM and ERCM, antenna selection based transceivers equipped with a compact antenna array is proposed. It is shown that a size-limited transceiver can improve its energy efficiency using a compact antenna array and thanks to receiver-end coupling matrix estimation (RCME) the additional training overhead is negligible.