Aggregated Packet Transmission in Duty-Cycled WSNs: Modeling and Performance Evaluation

Abstract– Duty cycling (DC) is a popular technique for energy conservation in wireless sensor networks that allows nodes to wake up and sleep periodically. Typically, a single packet transmission (SPT) occurs per cycle, leading to possibly long delay. With aggregated packet transmission (APT), nodes transmit a batch of packets in a single cycle. The potential benefits brought by an APT scheme include shorter delay, higher throughput and higher energy efficiency. In the literature, different analytical models have been proposed to evaluate the performance of SPT schemes. However, no analytical models for the APT mode on synchronous DC medium access control mechanisms exist. In this paper, we first develop a three-dimensional (3D) discrete time Markov chain (DTMC) model to evaluate the performance of an APT scheme with packet retransmission enabled. The proposed model captures the dynamics of the state of the queue of nodes and the retransmission status, as well as the evolution of the number of active nodes in the network, i.e., nodes with a non-empty queue. We then study the number of retransmissions needed to transmit a packet successfully. Based on the observations, we develop another less complex DTMC model with infinite retransmissions which embodies only two dimensions. Furthermore, we extend the 3D model into a four-dimensional model by considering error-prone channel conditions. The proposed models are adopted to determine packet
delay, throughput, packet loss, energy consumption, and energy efficiency. Furthermore the analytical models are validated through discrete-event based simulations. Numerical results show that an APT scheme achieves substantially better performance than its SPT counterpart in terms of delay, throughput, packet loss and energy efficiency, and that the developed analytical models reveal precisely the behavior of the APT scheme.