Unified and Distributed QoS-Driven Cell Association Algorithms in Heterogeneous Networks

TL;DR

This paper proposes a unified, distributed algorithm for cell association in heterogeneous networks that optimizes long-term rate utility and outage probability, improving performance over traditional SINR-based schemes.

Contribution

It introduces a novel unified distributed algorithm for cell association in HetNets, applicable to different QoS constraints, with low message passing requirements.

Findings

The proposed algorithm outperforms SINR-based schemes in simulations.

It effectively handles both long-term rate maximization and outage minimization.

The method reduces message passing in distributed cell association.

Abstract

This paper addresses the cell association problem in the downlink of a multi-tier heterogeneous network (HetNet), where base stations (BSs) have finite number of resource blocks (RBs) available to distribute among their associated users. Two problems are defined and treated in this paper: sum utility of long term rate maximization with long term rate quality of service (QoS) constraints, and global outage probability minimization with outage QoS constraints. The first problem is well-suited for low mobility environments, while the second problem provides a framework to deal with environments with fast fading. The defined optimization problems in this paper are solved in two phases: cell association phase followed by the optional RB distribution phase. We show that the cell association phase of both problems have the same structure. Based on this similarity, we propose a unified distributed algorithm with low levels of message passing to for the cell association phase. This distributed algorithm is derived by relaxing the association constraints and using Lagrange dual decomposition method. In the RB distribution phase, the remaining RBs after the cell association phase are distributed among the users. Simulation results show the superiority of our distributed cell association scheme compared to schemes that are based on maximum signal to interference plus noise ratio (SINR).