Mobile systems monitoring is an application area for Mobile Wireless Sensor Networks (MWSN), which introduces some specific challenges. Delay/Disruption architecture tackles some of these issues, such as delay and connectivity disruptions, and thus has already been used in this context. However, WSN nodes have severe limitations, concerning storage and processing capabilities. This performance problem has not been investigated as it deserves and this is the purpose of this paper. We propose the FREAK scheme which aims at reducing the computation while performance remains high. This scheme relies on the mean frequency of past encounter with the base station. Transmissions are driven by this metric. The FREAK solution is keen because we assume that future can be predicted from the past events. We also analyse the acknowledgements effects on performance. Our proposition is evaluated through simulations based on real traces. FREAK is compared to several replication and quota-based mainstream DTN solutions and achieves quite better performance in realistic scenarios.
Both WSNs (Wireless Sensor Networks) and observation satellites are able to get measurements from a geographic area. To interconnect these technologies, we propose to use a store-carry-and-forward architecture relying on the DTN (Disruption and Delay Tolerant Networking) Bundle Protocol. This architecture aims at being generic, so it is application-agnostic and suits a wide range of scenarios. WSN may collect sporadically large data volume while terrestrial stations communicating with Low Earth Orbit (LEO) satellites have to endure long link disruptions when the satellite is not in the line of sight. These sporadic growths within the WSN coupled with the large latency on satellite links require to schedule data to provide quality of service to several flows. We propose a scheduling policy based on deadline of Bundles and compare it with classical DTN solutions.
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