Throughput Analysis of Massive MIMO Uplink with Low-Resolution ADCs

摘要

We investigate the uplink throughput achievable by a multiple-user (MU)massive multiple-input multiple-output (MIMO) system in which the base stationis equipped with a large number of low-resolution analog-to-digital converters(ADCs). Our focus is on the case where neither the transmitter nor the receiverhave any a priori channel state information. This implies that the fadingrealizations have to be learned through pilot transmission followed by channelestimation at the receiver, based on coarsely quantized observations. Wepropose a novel channel estimator, based on Bussgang's decomposition, and anovel approximation to the rate achievable with finite-resolution ADCs, bothfor the case of finite-cardinality constellations and of Gaussian inputs, thatis accurate for a broad range of system parameters. Through numerical results,we illustrate that, for the 1-bit quantized case, pilot-based channelestimation together with maximal-ratio combing or zero-forcing detectionenables reliable multi-user communication with high-order constellations inspite of the severe nonlinearity introduced by the ADCs. Furthermore, we showthat the rate achievable in the infinite-resolution (no quantization) case canbe approached using ADCs with only a few bits of resolution. We finallyinvestigate the robustness of low-ADC-resolution MU-MIMO uplink against receivepower imbalances between the different users, caused for example by imperfectpower control.