On Uplink Performance of Multiuser Massive MIMO Relay Network With Limited RF Chains

TL;DR

This paper analyzes the uplink performance of a multiuser massive MIMO relay network with limited RF chains, deriving tight bounds for ergodic rate and optimizing power allocation for large antenna arrays.

Contribution

It introduces a new analysis for a cascaded two-hop channel with limited RF chains, providing closed-form bounds and power allocation strategies for massive MIMO relay systems.

Findings

Derived a tight ergodic rate bound for the two-hop channel.

Showed that source and relay powers can be scaled down with increasing antennas.

Validated results through simulations.

Abstract

This paper considers a multiuser massive multiple-input multiple-output uplink with the help of an analog amplify-and-forward relay. The base station equips a large array of $N_d$ antennas but is supported by a far smaller number of radio-frequency chains. By first deriving new results for a cascaded phase-aligned two-hop channel, we obtain a tight bound for the ergodic rate in closed form for both perfect and quantized channel phase information. The rate is characterized as a function of a scaled equivalent signal-to-noise ratio of the two-hop channel. It implies that the source and relay powers can be respectively scaled down as $1/N_d^a$ and $1/N_d^{1-a}~ (0\!\leq\!a\!\leq\!1)$ for an asymptotically unchanged sum rate. Then for the rate maximization, the problem of power allocation is optimized with closed-form solutions. Simulation results verified the observations of our derived results.