The impact of multiuser diversity on space-time block coding

We consider a scenario in which K active data users, each of which is equipped with multiple antenna elements, are served by a multi-antenna element base station (BS). We focus on the downlink channel, where space-time block coding scheme is employed and assume that channel state information (CSI) is reported to the BS by all users and on a per frame basis. Using a scoring function at the BS, time resources are allocated to the user with the best instantaneous effective SNR, facilitating a multiuser diversity mechanism. Using order statistics, we compute histograms and cumulative distribution functions of the effective SNR at the space-time combiner output and assess on the interactions between multiuser diversity and spatial diversity.