A diversity order design of linearly precoded MU-MIMO downlink system

Recently, Muti-User MIMO (MU-MIMO) downlink system which uses multiple antennas at Base Station (BS) and accommodates multiple users with multiple receive antennas attracts much attention. It can achieve a high channel capacity when the channel state information is known both at BS and each User Equipment (UE). There exist linear and non-linear MU-MIMO downlink schemes, but the linear scheme is considered more easily to be implemented and adjusted. Linear Block Diagonalization (BD) has been proposed in order to cancel the Inter-User Interference (IUI), and combined with the Eigenbeam-Space Division Multiplexing (E-SDM). In this paper, by noting that the block size of each user channel matrix in BD becomes (number of receive antennas of each UE) × (nullity of the matrix constituted by other users), we design the BD + ESDM scheme based on the down link quality of each UE, i.e., the diversity order. We made simulations for some examples and show the effectiveness of design method based on the diversity order of each UE.