Energy Saving in Cellular Networks by Dynamic RS–BS Association and BS Switching

In this paper, we propose a dynamic scheme that reduces energy consumption in relay-assisted cellular networks by switching light-loaded base stations (BSs) into sleeping mode and by transferring the traffic load in these cells to neighboring cells using dynamic relay-station-BS (RS-BS) associations. We first investigate how to determine the RS-BS associations to guarantee the coverage when the BS modes are given. The problem is modeled as a generalized assignment problem (GAP) that is NP-hard, and a heuristic algorithm is then proposed. Based on the proposed RS-BS association algorithm, a tabu search approach, which finds the combination of BS modes, is presented. Simulation results show that our proposed scheme makes the active BS sets to dynamically change as the traffic load varies, and in the given scenario, the energy consumption of BSs can be reduced by nearly 40% when the traffic load is low.