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

Design and Simulation of Resilient RF Receivers for 5G Interference Mitigation Using MATLAB

Introduction: Advanced terminal capabilities increase mobile broadband traffic, straining spectrum resources. Traditional methods like base stations are expensive. Heterogeneous networks (HetNets) using pico cells attempt to improve efficiency, however interference persists. A suggested mitigation technique uses the modified greatest weighting delay first (MLWDF) algorithm for resource allocation and reception processing, which performs well in simulations. Space, time, frequency, time-frequency, and coding domain interference reduction methods are investigated, each having hardware requirements and restrictions. Aim and objectives: The study uses MATLAB to construct and simulate robust RF receivers. Enhancing 5G communication network interference reduction is the goal. Method: Simulink is used to study transmitter and receiver RF losses, including I/Q imbalances, phase noise, and power amplifier non-linearity. Spectrum masks, error vector magnitudes, and peaks-to-average power ratios measure performance. Simulink models examine constellation distortion, neighboring channel rejection, and packet error rates in 802.11ax and 5G waveform reception due to RF impairments. The paper stresses the necessity of reliable data measurement for RF interference analysis and discusses interference mitigation. Results: Comparing Error Vector Magnitudes (EVMs) in Case 1 and Case 2 shows how NR interference affects HE receptions. EVMs approach -20 dB in Case 1 without NR interference. In Case 2, NR interference distorts constellations and lowers EVMs to -17 dB, suggesting poor reception. ACRs demonstrate NR-free channel separation by measuring power differences. The future investigation involves analyzing ACRs with HE waveforms as interferers and examining system behavior under different interference situations. Conclusion: To reduce non-idealities in mobile communication transceivers, this thesis presents digital projection interpolation and Wiener-SAF for leakage route and receiver nonlinearity estimation

Two-way CSI-assisted AF relaying with HPA nonlinearity

In this paper, we investigate half-duplex two-way dual-hop channel state information (CSI)-assisted amplify-and-forward (AF) relaying in the presence of high-power amplifier (HPA) nonlinearity at relays. The expression for the end-to-end signal-to-noise ratio (SNR) is derived as per the modified system model by taking into account the interference caused by relaying scheme and HPA nonlinearity. The system performance of the considered relaying network is evaluated in terms of average symbol error probability (SEP) in Nakagami-$m$ fading channels, by making use of the moment-generating function (MGF) approach. Numerical results are provided and show the effects of several parameters, such as quadrature amplitude modulation (QAM) order, number of relays, HPA parameters, and Nakagami parameter, on performance