1Effects of Channel Prediction for Transmit Antenna Selection with Maximal Ratio Combining in Rayleigh Fading

Abstract—Antenna selection is a low-complexity method for pragmatically exploiting spatial diversity in wireless systems. It has potentially reduced hardware cost compared to space-time or MIMO (multiple-input and multiple-output) coding, due to the reduction in the amount of radio frequency (RF) hardware required. Whilst receive antenna selection is perhaps more com-mon, transmit antenna selection also offers several advantages, particularly for hardware-costly transmit schemes such as those requiring linearisation. In use, transmit antenna selection (TAS) requires at least partial channel knowledge at the transmitter in order to perform selection. This knowledge usually comes in the form of an index to the best set of antenna/antennas fed back from the receiver; which implies a delay between the channel being sampled (at the receiver) and this knowledge being acted upon (at the transmitter). In this paper, performance degradation due to outdated channel knowledge is determined analytically, and related to channel characteristics. A predictive scheme is then developed to mitigate against delay-induced degradation. Several factors relating to TAS system performance under different channel scenarios both with and without mitigation are explored. Closed form expressions for performance metrics such as bit error rate (BER), outage probability, average signal-to-noise ratio (SNR) gain and higher order moments of output SNR are derived and verified by simulations. The impact of prediction is analyzed for different TAS setups and channel prediction scenarios, as are various system design parameters. I