Impact of feedback errors in multiuser diversity systems

Research in recent years has been focusing on the role of multiuser diversity in enhancing the throughput of wireless networks. Random channel fluctuations induced by fading are independent among users and can be exploited by a smart scheduler Kith partial channel information (i.e., signal to noise ratio) to increase the overall system spectral efficiency. In this paper we analyze the performances of a multiuser diversity system taking into account the feedback errors due to channel variability. Feedback error has been modeled as a Gaussian random variable with variance depending on Doppler spread. Also, based on a block fading channel model, we introduce a closed expression for the throughput as a function of the system parameters, such as packet length and data rates thresholds, and channel characteristics, such as Doppler spread. From the analysis of the performance, we show a tradeoff between multiuser diversity and mobility, and also between rate adaptivity and channel estimation errors.