Availability of Channel Reciprocity for Antenna Selection in OFDM TDD Systems

Channel reciprocity is a major merit of time division duplex (TDD) systems. In such systems. the reference symbol (RS) not only helps the receiver to do coherent detection, but also implicitly feedback channel state information (CSI) which could help the transmission in the other direction. Transmitter will get more up to date and less approximated CSI in implicit feedback methods than explicit feedback methods as in frequency division duplex (FDD) mode. However, many factors will invalidate this merit including channel estimation error of the RS at the transmitter, UE speed and CSI delay between the time to get it and the time to use it, and RF mismatch etc. This paper will focus on the first two factors assuming evolved universal terrestrial radio access (EUTRA) uplink transmission as a context. A simple system model is given and numerical performance is mainly evaluated through simulations.