Enhanced-Power Saving Semi-Persistent Scheduler for VoLTE in LTE-Advanced

Abstract

Power saving-semipersistent scheduler (PS-SPS) for voice over LTE (VoLTE) traffic was proposed in the downlink of LTE-A cell to reduce the energy consumption of the eNodeB. PS-SPS introduces the energy saving ability through a modification of traditional SPS (T-SPS) in allocating downlink Physical Resource Block (PRBs) to VoLTE users. In this paper, we first identify the drawbacks of PS-SPS that might curtail its energy saving capability and also degrade its capacity (maximum number of calls that can be supported simultaneously) compared with T-SPS. We then propose a novel SPS scheduler called enhanced-PS-SPS (E-PS-SPS) to allocate downlink PRBs to VoLTE users more efficiently compared with PS-SPS. Next, we build analytical models to derive expressions for capacity and eNodeB energy consumption for both PS-SPS and E-PS-SPS. Our analytical results show that E-PS-SPS not only outperforms PS-SPS in capacity by a substantial margin, but also considerably improves the energy saving. The analysis results are validated using simulations. Furthermore, owing to the modeling complexity of T-SPS, we bound its performance in terms of PS-SPS and E-PS-SPS through heuristic arguments. Simulation results validate our analytical bounds and also show that the proposed E-PS-SPS outperforms T-SPS also both in capacity and energy consumption, unlike PS-SPS whose capacity is lower than T-SPS.