Massive MIMO Performance with Pilot Reuse

Achieving the promising gains of massive multiple- input multiple-output (MIMO) relies on accurate channel state information. In this paper, results from detailed time-dynamic system simulations of reciprocity based massive MIMO systems in the 3GPP 3D scenarios are presented. Downlink (DL) multi- user MIMO performance is found to be sensitive to errors in channel estimates obtained from uplink (UL) sounding. Inter-cell coordination of UL sounding sequences by applying a comb reuse pattern in an orthogonal frequency-division multiplexing based system is shown to significantly improve DL system performance. With a comb reuse 1/3 or 1/9 pattern, results show up to 75\% increased DL non-full buffer traffic capacity, thanks to reduced inter-cell interference in the channel estimation.