Inter-tier Interference Suppression in Heterogeneous Cloud Radio Access Networks

TL;DR

This paper investigates interference suppression techniques in heterogeneous cloud radio access networks, proposing collaboration and beamforming methods, deriving performance metrics, and optimizing resource allocation to enhance system capacity and reliability.

Contribution

It introduces novel interference suppression strategies with analytical performance evaluation and convex optimization-based resource allocation in H-CRANs.

Findings

IC and BF schemes improve system performance.

Derived closed-form outage and capacity expressions.

Sum rates increase linearly with transmit power.

Abstract

Incorporating cloud computing into heterogeneous networks, the heterogeneous cloud radio access network (H-CRAN) has been proposed as a promising paradigm to enhance both spectral and energy efficiencies. Developing interference suppression strategies is critical for suppressing the inter-tier interference between remote radio heads (RRHs) and a macro base station (MBS) in H-CRANs. In this paper, inter-tier interference suppression techniques are considered in the contexts of collaborative processing and cooperative radio resource allocation (CRRA). In particular, interference collaboration (IC) and beamforming (BF) are proposed to suppress the inter-tier interference, and their corresponding performance is evaluated. Closed-form expressions for the overall outage probabilities, system capacities, and average bit error rates under these two schemes are derived. Furthermore, IC and BF based CRRA optimization models are presented to maximize the RRH-accessed users' sum rates via power allocation, which is solved with convex optimization. Simulation results demonstrate that the derived expressions for these performance metrics for IC and BF are accurate; and the relative performance between IC and BF schemes depends on system parameters, such as the number of antennas at the MBS, the number of RRHs, and the target signal-to-interference-plus-noise ratio threshold. Furthermore, it is seen that the sum rates of IC and BF schemes increase almost linearly with the transmit power threshold under the proposed CRRA optimization solution.