Joint time switching and rate allocation optimization for energy efficiency in wireless multimedia sensor networks

In wireless multimedia sensor networks (WMSNs), multimedia contents from remote areas are captured by camera sensors (CSs) and sent to data center via cluster heads (CHs) and base stations (BSs) for the purpose of monitoring. The problem in WMSNs is that enabling multimedia streaming, e.g., video streaming, demands high quality and consumes considerable bandwidth and energy resources, meanwhile, the CSs, CHs, and wireless channels are energy- and bandwidth-constrained and diverse lossy. In this paper, we propose a joint time switching and rate allocation optimization scheme for WMSNs to minimize energy consumed by capturing, packetizing, and transmitting the video contents, while conserving bandwidth and guaranteeing high quality. In particular, firstly, a time switching optimization (SOP) problem is formulated and solved for optimal capture durations of each CS, so as to minimize the capture energy consumption. Secondly, to minimize energy consumed by packetizing and transmitting, we formulate a rate allocation optimization (ROP) problem and solve it for optimal rates allocated to each video for packetizing and transmitting under bandwidth resource and quality constraints. Simulation results show that our proposed SOP and ROP schemes can significantly enhance the performance of WMSNs in terms of minimum energy consumption, bandwidth efficiency, and high quality.