Supporting multi-hop and multi-packet transmission in asynchronous WSNs

Cross-layer design approaches explore the benefits of information exchange between different layers of the network stack. In this paper, we present a cross-layer design approach to support multi-hop and multi-packet routing in asynchronous networks. This is achieved by realizing implicit temporary synchronization at the MAC layer while using multi-hop, multi-packet routing information, and current duty-cycling information. We formally present the cost of information sharing and maintenance at different levels of granularity across network layers and among neighboring nodes. The benefits of information sharing and communication are tremendous. The proposed cross-layer approach can be applied to any asynchronous MAC scheme. For example, when applied to RI-MAC (one of the most efficient and recent asynchronous MAC protocols), it reduces its latency by 34% and improves power consumption by 32% on a 16-node clique network, without compromising throughput. The proposed approach was also tested on a 10-node chain and a 25-node cross chain at various traffic loads and flows; it showed great improvements in latency without affecting power consumption or delivery ratio.