Robust channel esimaton and schedulng for heterogeneous muluser masve MIMO sysems
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VDE VERLAG GMBH, Berlin, Offenbach, Germany. We consder a correlated muluser (MU) massive mulple-input mulple-output (MIMO) downlink channel n which many heterogeneous users have derent channel qualies (e., dierent path-oses) to a base staton (BS) equipped wih a arge antenna array. Ung he theory of extreme values of regularly varying functions, we characterize the scaling laws of he achievable sum-rate of the sysem, when both numbers of BS antennas and users grow arge. We then prove that for a large number of users, a simple uer schedulng that chooses the uers wih the largest insantaneous channel vector norms based on the global channel sate informaton (CSI) can significanty mprove he achievable sysem sum-rate. Finally, since he schedulng method needs the global CSI esmate to operate, we propose an efficient algorithm based on ow-rank matrix approximaton o esmate the global CSI wh a moderate number of trainng signals. Analyss and numerical simulatons show hat the proposed scheme provides favourable results in terms of system sum-rate performance and computatonal complexity.