Effects of imperfect channel state information on the capacity of broadcast OSDMA-MIMO systems

The capacity of a multiple input multiple output (MIMO) broadcast system with orthogonal space division multiple access (OSDMA) is studied under the assumptions of noisy and/or delayed channel state information (CSI) available at the transmitter. The impact of channel estimation errors and outdated CSI is evaluated both analytically and through Monte Carlo simulations for varying system parameters (i.e., channel decorrelation, number of users, number of antennas). It is found that channel variability is the predominant cause of performance degradation in a realistic setting, where feedback of CSI from the receivers to the transmitter takes a finite amount of time, thus suggesting to limit the use of OSDMA to channels varying slowly enough.