Performance analysis of uplink sounding in frequency selective fading channel

Channel sounding is an efficient technique to get the channel state information (CSI) in time division duplex wireless communication systems. The base station can employ downlink beamforming by estimating the CSI from the sounding signal. To support a large number of users, the sounding signals of multiple users are multiplexed in the same physical resource unit by means of decimation separation (DS) or cyclic shift separation (CSS). This paper investigates the performance of DS and CSS-based channel sounding techniques in frequency selective fading channel. It is shown that the sounding performance is associated with the number of users, decimation or maximum cyclic shift index, frequency channel correlation, and channel estimation method.1