Effect of Outdated CSI in a Multiuser TAS/MRC System over Correlated Nakagami-m fading

Abstract

The TAS/MRC system is a widely accepted technique to reduce the complexity level of a multiuser MIMO system with little reduction in the performance. This increases the practical applicability of TAS/MRC system. In TAS/MRC algorithm the channel state information (CSI) is provided to the transmitter for selection of best transmitting antenna for better system performance. However, two important factors may reduce the performance of the TAS/MRC system considerably, out dated CSI and the antenna correlation. For analysis of TAS/MRC system, it has been considered that the CSI is being sent back to the receiver through a loss less channel. For practical applications this is not true, hence, the error in CSI needs to be considered in the analysis. Similarly the performance of MRC receiver degrades considerably due to the correlation among the receiving antennas. In this paper we have analysed a TAS/MRC system considering both outdated CSI and exponential correlation for a Nakagami-m fading environment. Various performance measures have been presented in this analysis and the effect of both correlation and outdated CSI have been studied. It has been found that small amplitude error in CSI, may degrade the performance of the system considerably, compared to the phase error of the CSI.