On the MIMO Capacity with Residual Transceiver Hardware Impairments

Radio-frequency (RF) impairments in the transceiver hardware of communication systems (e.g., phase noise (PN), high power amplifier (HPA) nonlinearities, or in-phase/quadrature-phase (I/Q) imbalance) can severely degrade the performance of traditional multiple-input multiple-output (MIMO) systems. Although calibration algorithms can partially compensate these impairments, the remaining distortion still has substantial impact. Despite this, most prior works have not analyzed this type of distortion. In this paper, we investigate the impact of residual transceiver hardware impairments on the MIMO system performance. In particular, we consider a transceiver impairment model, which has been experimentally validated, and derive analytical ergodic capacity expressions for both exact and high signal-to-noise ratios (SNRs). We demonstrate that the capacity saturates in the high-SNR regime, thereby creating a finite capacity ceiling. We also present a linear approximation for the ergodic capacity in the low-SNR regime, and show that impairments have only a second-order impact on the capacity. Furthermore, we analyze the effect of transceiver impairments on large-scale MIMO systems; interestingly, we prove that if one increases the number of antennas at one side only, the capacity behaves similar to the finite-dimensional case. On the contrary, if the number of antennas on both sides increases with a fixed ratio, the capacity ceiling vanishes; thus, impairments cause only a bounded offset in the capacity compared to the ideal transceiver hardware case.Comment: Accepted for publication at the IEEE International Conference on Communications (ICC 2014), 7 pages, 6 figure

Effect of non-linearity on the performance of a MIMO zero-forcing receiver with channel estimation errors

Non-linear amplitude distortion may be the key impairment in some practical multiple-input multiple-output (MIMO) communications systems. However, there are only a few past investigations addressing its impact on the system performance. In this paper, we derive an approximate upper bound on the bit error rate for MIMO zero-forcing receivers with M-ary quadrature amplitude modulation (MQAM) in the presence of channel estimation error, which is valid for any order of non-linearity and arbitrary numbers of transmit and receive antennas. In the absence of channel estimation error, the results derived herein give a true BER upper bound. Comparison with Monte Carlo simulations suggest that the theoretical bound is accurate and useful for practical system design. © 2007 IEEE