Range Assignment for Power Optimization in Load-Coupled Heterogeneous Networks

TL;DR

This paper addresses energy optimization in LTE HetNets by optimizing user association through cell-specific offsets, proving full load operation is optimal and introducing a tabu search algorithm for efficient offset optimization.

Contribution

It introduces a novel offset optimization method for load-coupled HetNets, proves full load operation is optimal regardless of power limits, and demonstrates the effectiveness of a tabu search algorithm.

Findings

TSO significantly reduces transmission energy compared to uniform offsets.

Operating at full load is proven to be optimal regardless of power constraints.

NP-hardness of the optimization problem is established.

Abstract

We consider the problem of transmission energy op- timization via range assignment for Low Power Nodes (LPNs) in Long Term Evolution (LTE) Heterogenous Networks (HetNets). The optimization is subject to the load coupling model, where the cells interfere with one another. Each cell provides data service for its users so as to maintain a target Quality-of-Service (QoS). We prove that, irrespective the presence of maximum power limit or its value, operating at full load is optimal. We perform energy minimization by optimizing the association between User Equipments (UEs) and cells via selecting cell- specific offsets on LPNs. Moreover, the optimization problem is proved to be NP-hard. We propose a tabu search algorithm for offset optimization (TSO). For each offset, TSO computes the optimal power solution such that all cells operate at full load. Numerical results demonstrate the significant performance improvement of TSO on optimizing the sum transmission energy, compared to the conventional solution where uniform offset is used for all LPNs.