How to Survive 10 Years’ Life Time for Machine Type Devices: A Study of Random Access With Sleeping-Awake Cycle

Delivering as many data packets as possible and making the life time of the network as long as possible is one fundamental request for battery-driven wireless network design, where sleeping schemes are usually adopted for prolonging the life time, while, at the sacrifice of the throughput performance. For random access networks, fulfilling this fundamental request is rather challenging due to the distributed nature of the access behavior of nodes. This paper considers massive Machine-Type Communication (mMTC) networks where each node adapts the representative random access scheme Aloha and periodical sleeping-awake cycle. We aim to address how to maximize the life-time throughput of each node, i.e., average number of packets each node can successfully deliver during its life time, with a guarantee of targeted life time via optimal selection of the channel access probability and the sleeping ratio of each node. By deriving the explicit expressions of the life time and the life-time throughput of each node and jointly tuning both the channel access probability and the sleeping ratio, we characterize the maximum life-time throughput with targeted life time, and the corresponding optimal settings. The analysis reveals that if only the channel access probability is optimally tuned, then the throughput and life-time throughput cannot be optimized simultaneously when the network becomes saturated with a large packet arrival rate. In contrast, the network would operate at unsaturated conditions via the joint tuning of the access probability and the sleeping ratio. In this case, the maximum life-time throughput always grows with the packet arrival rate. In addition, it is shown that the effect of the life-time constraint becomes significant only when it exceeds a threshold, where maximum life-time throughput will sacrifice for life-time expectation. The analysis sheds important light on the access and sleeping scheme design of practical Aloha-type networks. By taking Narrow Band-IoT with Power Saving Mode (PSM) as an example, extensive simulation results corroborate that with the proposed optimal setting, the life-time throughput could be significantly improved, especially when the life time requirement is demanding, e.g., 10 years without battery replacement.