Improving routing performance when several routing protocols are used sequentially in a WSN

Wireless sensor networks can accommodate multiple applications by using a multi-stack architecture in order to deliver a large number of QoS. Multi-stack architectures can be optimized by allowing packet exchanges between stacks. However, routing loops may appear because of these exchanges. In this paper, we highlight the problem of routing loops generated when the same packet is routed according to two routing protocols. We define the delayable property of routing protocols by considering that some nodes might hold packets in order to avoid loops in the network. We show that minimizing the number of such nodes is an NP-complete problem. Then, we propose two heuristics to address this issue: a centralized deterministic heuristic requiring a global knowledge of the network, and a distributed stochastic heuristic reducing the number of hops from source to destination. Our two heuristics show important benefits: we reach a gain of up to 67% for the first heuristic and of up to 53% for the second heuristic, in terms of number of hops.