Performance Analysis of MIMO-NOMA Systems with Randomly Deployed Users

TL;DR

This paper provides a comprehensive performance analysis of MIMO-NOMA systems with randomly deployed users, considering spatial randomness, antenna correlation, and fading, deriving closed-form expressions and asymptotic behaviors.

Contribution

It introduces exact closed-form expressions for outage probability and goodput in MIMO-NOMA with random user deployment, including asymptotic analysis under different SNR regimes.

Findings

Diversity order is $oxed{ ext{N}_r - ext{M} + 1}$.

Outage probability scales with cell radius as $O(D^{ ext{alpha}( ext{N}_r - ext{M} + 1) + 2k})$.

Goodput scales as $O(D^{2})$ when $D o 0$ and $O(D^{-2})$ when $D o ext{infinity}$.

Abstract

This paper investigates the performance of Multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) systems with randomly deployed users, where the randomly deployed NOMA users follow Poisson point process (PPP), the spatial correlation between MIMO channels are characterized by using Kronecker model, and the composite channel model is used to capture large-scale fading as well as small-scale fading. The spatial randomness of users' distribution, the spatial correlation among antennas and large-scale fading will severally impact the system performance, but they are seldom considered in prior literature for MIMO-NOMA systems, and the consideration of all these impact factors challenges the analysis. Based on zero-forcing (ZF) detection, the exact expressions for both the average outage probability and the average goodput are derived in closed-form. Moreover, the asymptotic analyses are conducted for both high signal-to-noise ratio (SNR) (/small cell radius) and low SNR (/large cell radius) to gain more insightful results. In particular, the diversity order is given by $\delta = {{N_r} - {M} + 1}$, the average outage probability of $k$-th nearest user to the base station follows a scaling law of $O\left({D^{\alpha \left( {{N_r} - {M} + 1} \right) + 2k}}\right)$, the average goodput scales as $O({D^{2}})$ and $O({D^{-2}})$ as $D \to 0$ and $D \to \infty$, respectively, where $N_r$, $M$, $\alpha$ and $D$ stand for the number of receive antennas, the total number of data streams, the path loss exponent and the cell radius, respectively. The analytical results are finally validated through the numerical analysis.