Resilience through multicast – An optimization model for multi-hop wireless sensor networks

In this paper we study resilience of TDMA-based wireless sensor networks to node failures. We investigate exploiting mutlicast routing for providing redundancy in the number of gateways used by data streams, so as to protect them against gateway failures. To do this, we develop an optimization model aiming at packet traffic throughput maximization composed of three mixed-integer programming problem formulations and corresponding solution algorithms. The first formulation assumes predefined multicast routing trees and fixed gateway locations, and optimizes the TDMA frame composition. The second one adds routing trees optimization, while the third formulation additionally includes optimization of gateway locations. We present a numerical study illustrating effectiveness of our model, including efficiency of the solution algorithms. Our results show that substantial gains in traffic throughput can be obtained by including routing trees optimization and optimal gateways selection, especially for high levels of redundancy.