Energy-efficient forwarding strategies for geographic routing in lossy wireless sensor networks

Abstract

Recent experimental studies have shown that wireless links in real sensor networks can be extremely unreliable, deviating to a large extent from the idealized perfect-receptionwithin-range models used in common network simulation tools. Previously proposed geographic routing protocols commonly employ a maximum-distance greedy forwarding technique that works well in ideal conditions. However, such a forwarding technique performs poorly in realistic conditions as it tends to forward packets on lossy links. We identify and illustrate this weak-link problem and the related distancehop trade-off, whereby energy efficient geographic forwarding must strike a balance between shorter, high-quality links, and longer lossy links. The study is done for scenarios with and without automatic repeat request (ARQ).Based on an analytical link loss model, we study the distance-hop trade-off via mathematical analysis and extensive simulations of a wide array of blacklisting/link-selection strategies; we also validate some strategies using a set of real experiments on motes. Our analysis, simulations and experiments all show that the product of the packet reception rate (PRR) and the distance traversed towards destination is the optimal forwarding metric for the ARQ case, and is a good metric even without ARQ. Nodes using this metric often take advantage of neighbors in the transitional region (high-variance links). Our results also show that receptionbased forwarding strategies are more efficient than purely distance-based strategies; relative blacklisting schemes reduce disconnections and achieve higher delivery rates than absolute blacklisting schemes; and that ARQ schemes become more important in larger networks.

An exploration of geographic routing with k-hop based searching in wireless sensor networks

“…As reported in [12], the product of PRR and the distance progress towards destination is a good decision metric. It is often more effective than a purely distance based routing metric in systems with time-varying links due to a better capture of the wireless nature.…”

“…In general, the link cost can be defined by the application objectives such as delay, energy consumption or link quality. In [12], beyond conventional geographic greedy routing in maximum distance advance which may perform poorly in lossy wireless links, a study of routing strategies in distance-hop tradeoff is conducted. Results show that the product of PRR and the distance traversed towards destination is a routing metric for packet forwarding in general.…”

“…In reference to the above model and the discussions in [12], we will adopt the following three settings based on [23]. They represent different environments and characteristics.…”

“…On the other hand, the new routing metric has taken into account both the proximity and link quality, and better capture the expected progress per transmission [7]. Discussions on this can also be found in [12].…”

“…A routing metric beyond simple greedy method is thus necessary and favorable. To conduct the study in a lossy and dynamic WSN, we adopt the model used in [12] which also considers link quality transitional regions [10]. Meanwhile, a new routing metric which incorporates the proximity to destination and link reliability is proposed and generalized.…”