Performance of adaptive channel state information (CSI) in multi–user mimo wireless communication systems

Abstract

Multiple Input Multiple Output (MIMO) is a ground breaking technology now-a-days in the wireless communication industry. MIMO offers tremendous amount of increase in the data rates, throughput, and link reliability without the use of additional resources (time and frequency e.t.c.). In order to achieve high data rates and throughputs, the channel must be known to the transmitter to adapt to transmission in current channel conditions which is crucial for achieving high date rates in MIMO systems. Accurate power control, scheduling and resource allocation can be done if CSI is available at both the transmitter and the receiver. However, there is a major issue with CSI at the transmitter. The wireless channel is unpredictable and changing rapidly, thus, there is a need to estimate the channel regularly. There are two methods in this regard namely reciprocity mechanism and feedback mechanism. This research work mainly focuses on both the reciprocity mechanism and the feedback mechanism. Simulations have been carried out for both mechanisms in Rayleigh and Rician fading channels. In case of feedback mechanism, as CSI is fed back to the transmitter side, errors in CSI are introduced due to wireless channel. This limitation is addressed using suitable channel coding techniques to make both the mechanisms less erroneous.