Prohibitive-link Detection and Routing Protocol

Abstract

In this paper we investigate the limits of routing according to left- or righthand rule (LHR). Using LHR, a node upon receipt of a message will forward to the neighbour that sits next in counter-clockwise order in the network graph. When used to recover from greedy routing failures, LHR guarantees success if implemented over planar graphs. We note, however, that if planarity is violated then LHR is only guaranteed to eventually return to the point of origin. Our work seeks to understand why. An enumeration and analysis of possible intersections leads us to propose the Prohibitive-link Detection and Routing Protocol (PDRP) that can guarantee delivery over non-planar graphs. As the name implies, the protocol detects and circumvents the ‘bad' links that hamper LHR. Our implementation of PDRP in TinyOS reveals the same level of service as face-routing protocols despite preserving most intersecting links in the network.