A decade ago as wireless sensor network (sensornet) research took off many researchers in the field eschewed the use of IP as inadequate and in contradiction to the needs of sensornets. Since those beginnings, the field has matured substantially, a huge collection of protocols have been invented and evaluated, and we have gained experience in how sensornets are used in practice. Over this same period, the Internet has also evolved with the introduction of IPv6 that addresses scalability and easy configuration and management.

In this dissertation, we present the design of a complete IPv6-based network architecture for sensornets that preserves the protocol layering but increases cross-layer visibility. We equate the IP link to radio neighbors, giving network- and higher-layer protocols necessary visibility into radio connectivity. We show how the link can appear always-on while operating a low duty-cycles. An adaptation layer between the link and network layers applies cross-layer optimizations to reduce packet headers and per-node state. At the network layer, we address issues of effective configuration and management over ad-hoc multihop networks as well as efficient forwarding and routing through cooperation with the link layer. By providing effective end-to-end datagram delivery, transport- and application-layer protocols remain largely unchanged.

We validate the architecture with a complete implementation that is the first to incorporate many sensornet techniques into an IP architecture, including duty-cycled links, header compression, adaptive hop-by-hop forwarding, and efficient routing. In addition to providing end-to-end interoperability with existing non-sensornet IP devices, our implementation outperforms existing sensornet approaches that do not adhere to any particular architecture or standard. In a real-world application, the implementation achieved an average duty-cycle of 0.65%, per-hop latency of 62ms, and delivery rate of 99.98% over four weeks with each node generating 1 pkt/min. In light of this demonstration of full IPv6 capability, we review the central arguments that led the field away from IP. We believe that the presence of an architecture, specifically an IPv6-based one, provides a strong foundation for sensornets going forward.




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