A Traffic Flows Scheme for User-BS Association in Green HetNets

Abstract

Energy efficiency in the next-generation of cellular networks is an important topic due to the expected increase in the number of nodes. Previous research has shown the relationship between the number of users connected to a cellular network base station (BS) and its energy consumption. For this reason, the study of optimal mechanisms that balance the load of users over the available base stations is a key element in the field of energy efficiency in cellular networks. However, the user-BS association process is not trivial because the problem explodes combinatorially. For this reason, it is necessary to explore mechanisms able to be executed in the order of milliseconds. In this paper, we compare two different user - BS association policies and their impact on grid consumption in a heterogeneous cellular network (HetNet) powered by hybrid energy sources (grid and renewable energy). The first proposal is based on a discrete optimization problem and the second is a relaxation that uses traffic flows. These schemes are compared to the traditional best-signal-level mechanism and evaluated in a realistic simulation scenario to study the impact on grid consumption, number of users served, and computation time. The new proposed user allocation policies result in lower grid electricity consumption and lower average unserved users compared to the traditional association scheme.