Throughput Scaling of MIMO Channels With Imperfect CSIT in the Low-SNR Regime

摘要

We study the effect of channel estimation error on the performance of water-filling in point-to-point multiple-input–multiple-output (MIMO) channels at low signal-to-noise ratios (SNRs). In this regard, we derive the water-filling throughput of a MIMO channel in the presence of imperfect channel state information at the transmitter (CSIT). The asymptotic growth rate for the throughput, i.e., $R$, is then found and is compared with the asymptotic growth rate for the capacity with perfect CSIT, i.e., $C^{rm P}$, as a function of the signal-to-estimation-error ratio (SER). We show that, at low SNR, for moderate values of the SER, water filling based on erroneous channel estimates can still achieve significant throughputs asymptotically.