MFACE: A Multicast Backbone-Assisted Face Traversal Algorithm for Arbitrary Planar Ad Hoc and Sensor Network Topologies

Face is a well-known localized routing protocol for ad hoc and sensor networks which guarantees delivery of the message as long as a path exists between the source and the destination. This is achieved by employing a left/right hand rule to route the message along the faces of a planar topology. Although face was developed for the unicast case, it has recently been used in combination with multicasting protocols, where there are multiple destinations. Some of the proposed solutions handle each destination separately and lead thus to increased energy consumption. Extensions of face recovery to the multicast case described so far are either limited to certain planar graphs or do not provide delivery guarantees. A recently described scheme employs multicast face recovery based on a so called multicast backbone. A multicast backbone is a Euclidean spanning tree which contains at least the source and the destination nodes. The idea of backbone assisted routing it to follow the edges of the backbone in order to deliver a multicast message to all spanned destination nodes. The existing backbone face routing scheme is however limited to a certain planar graph type and a certain backbone construction. One of the key aspects of the multicast face algorithm MFACE we propose in this work is that it may be applied on top of any planar topology. Moreover, our solution may be used as a generic framework since it is able to work with any arbitrary multicast backbone. In MFACE, any edge of the backbone originated at the source node will generate a new copy of the message which will be routed toward the set of destination nodes spanned by the corresponding edge. Whenever the message arrives at a face edge intersected by a backbone edge different from the initial edge, the message is split into two copies, both handling a disjoint subset of the multicast destinations which are defined by splitting the multicast backbone at that intersection point

Improving Routing Efficiency through Intermediate Target Based Geographic Routing

The greedy strategy of geographical routing may cause the local minimum problem when there is a hole in the routing area. It depends on other strategies such as perimeter routing to find a detour path, which can be long and result in inefficiency of the routing protocol. In this paper, we propose a new approach called Intermediate Target based Geographic Routing (ITGR) to solve the long detour path problem. The basic idea is to use previous experience to determine the destination areas that are shaded by the holes. The novelty of the approach is that a single forwarding path can be used to determine a shaded area that may cover many destination nodes. We design an efficient method for the source to find out whether a destination node belongs to a shaded area. The source then selects an intermediate node as the tentative target and greedily forwards packets to it, which in turn forwards the packet to the final destination by greedy routing. ITGR can combine multiple shaded areas to improve the efficiency of representation and routing. We perform simulations and demonstrate that ITGR significantly reduces the routing path length, compared with existing geographic routing protocols

Combined Coverage Area Reporting and Geographical Routing in Wireless Sensor-Actuator Networks for Cooperating with Unmanned Aerial Vehicles

In wireless sensor network (WSN) applications with multiple gateways, it is key to route location dependent subscriptions efficiently at two levels in the system. At the gateway level, data sinks must not waste the energy of the WSN by injecting subscriptions that are not relevant for the nodes in their coverage area and at WSN level, energy-efficient delivery of subscriptions to target areas is required. In this paper, we propose a mechanism in which (1) the WSN provides an accurate and up-to-date coverage area description to gateways and (2) the wireless sensor network re-uses the collected coverage area information to enable efficient geographical routing of location dependent subscriptions and other messages. The latter has a focus on routing of messages injected from sink nodes to nodes in the region of interest. Our proposed mechanisms are evaluated in simulation

An Analysis of Planarity in Face-Routing

In this report we investigate the limits of routing according to left- or right-hand 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. This is often referred to as face or geographic routing. In the current body of knowledge it is known that if planarity is violated then LHR is guaranteed only to eventually return to the point of origin. Our work seeks to understand why a non-planar environment stops LHR from making delivery guarantees. Our investigation begins with an analysis to enumerate all node con gurations that cause intersections. A trace over each con guration reveals that LHR is able to recover from all but a single case, the `umbrella' con guration so named for its appearance. We use this information to propose the Prohibitive Link Detection Protocol (PDLP) that can guarantee delivery over non-planar graphs using standard face-routing techniques. As the name implies, the protocol detects and circumvents the `bad' links that hamper LHR. The goal of this work is to maintain routing guarantees while disturbing the network graph as little as possible. In doing so, a new starting point emerges from which to build rich distributed protocols in the spirit of protocols such as CLDP and GDSTR

FAR: Face-Aware Routing for Mobicast in Large-Scale Sensor Networks

This paper presents FAR, a Face-Aware Routing protocol for mobicast, a spatiotemporal variant of multicast tailored for sensor networks with environmental mobility. FAR features face-routing and timed-forwarding for delivering a message to a mobile delivery zone. Both analytical and statistical results show that, FAR achieves reliable and just-in-time mes-sage delivery with only moderate communication and memory overhead. This paper also presents a novel distributed algorithm for spatial neighborhood discovery for FAR boot-strapping. The spatiotemporal performance and reliability of FAR are demonstrated via ns-2 simulations

Reliable Mobicast via Face-Aware Routing

This paper presents a novel protocol for a spatiotemporal variant of multicast called mobicast, designed to support message delivery in sensor and mobile ad hoc networks. The spatiotemporal character of mobicast relates to the obligation to deliver a message to all the nodes that will be present at time t in some geographic zone Z, where both the location and shape of the delivery zone are a function of time over some interval (tstart, tend). The protocol, called Face-Aware Routing (FAR), exploits ideas adapted from existing applications of face routing to achieve reliable mobicast delivery. The key features of the protocol are a routing strategy, which uses information confined solely to a node’s immediate spatial neighborhood, and a forwarding schedule, which employs only local topological information. Statistical results showing that, in uniformly distributed random disk graphs, the spatial neighborhood size is usually less than 20 suggest that FAR is likely to exhibit a low average memory cost. An estimation formula for the average size of the spatial neighborhood in random network is another analytical result reported in this paper. This paper also includes a novel and low cost distributed algorithm for spatial neighborhood discovery