Information rates for non-coherent multiantenna systems in the wideband regime

This work presents analytical upper and lower bounds on the information rate of a multiuser Rayleigh fading channel with no channel state information (CSI) at the transmitters or the receivers. These bounds are shown to converge whenever an individual user´s data rate is small compared with the bandwidth, e.g., when users can employ CDMA. The convergence will take place even when the aggregate spectral density is large, so that even though the individual users are in wideband, the system is not. The amount of spreading required for a given degree of convergence depends on the number of receive antennas. The paper presents exact analytical expressions for the information rates of both the block fading and the continuous correlated fading channel models in this regime. However, these results can be easily extended to more general channel models.