Reliable multi-channel scheduling for timely dissemination of aggregated data in wireless sensor networks

In wireless sensor networks (WSNs), nodes probe the environment and send their readings to an in situ base-station over multi-hop routes. To save energy and increase the throughput, in-network data aggregation is often pursued to remove redundancy and correlate the data en-route to the base-station. On the other hand, some applications are sensitive to data latency and deterministic medium access is provisioned. In this paper, we present a novel cross-layer approach called Reliable Multi-channel Scheduling for timely dissemination of Aggregated data (RMSA). RMSA ensures the collection reliability and reduces the latency in disseminating aggregated data to the base-station over multi-frequency radio links. The aim is to form an aggregation tree such that there are K disjoint paths from each node to the base-station and find a collision-free schedule for node transmissions so that the aggregated data reaches the base-station in minimal time. RMSA forms the aggregation tree with the objective of increasing the simultaneity of transmissions and reducing buffering delay. Aggregation nodes are picked and time-slots are allocated to the individual sensors so that the most number of ready nodes can transmit their data without delay. Colliding transmissions are avoided by the use of different radio channels. Our approach is validated through simulation and is shown to outperform previously published schemes.