Design of a buffer and channel adaptive LTE semi-persistent scheduler for M2M communications

One of the major limitations of the LTE system in context of Machine-to-Machine (M2M) communications is the excessive control signalling required for dynamic scheduling of radio resources. Although the queue awareness and link adaptation features of the dynamic scheduler can be very beneficial for M2M traffic as well, these two properties come at a cost of significant control overhead. In this paper, we propose an adaptive semi-persistent LTE uplink scheduler which reduces the control overhead by a significant level and utilizes the uplink capacity efficiently to satisfy the Quality of Service (QoS) requirements of M2M traffic. The concept of Semi-Persistent Scheduling (SPS) has already been implemented for Voice over IP (VoIP) service in the LTE standard. However, we have further developed this into an adaptive SPS scheme which can adapt to the sudden bursts of stochastic M2M traffic flow by utilizing the device buffer information as well as respond to the channel fluctuations caused by fading while satisfying the M2M packet delay constraints. The performance of the proposed adaptive SPS scheme has been compared to an LTE dynamic scheduler using the OPNET simulation software for fading channels. The simulation results demonstrate the adaptive SPS scheme to outperform the dynamic scheduler in terms of both control channel utilization and satisfying QoS requirements of M2M traffic.