A Review of Geocasting Protocols for a Mobile Ad Hoc Network∗ †

A mobile ad hoc network (MANET) is a network consisting of a set of mobile hosts capable of communicating with each other without the assistance of base stations. In this paper we review five existing protocols for geocasting in a MANET environment. The goal of a geocasting protocol is to deliver data packets to a group of nodes that are with a specified geographical area, i.e., the geocast region. In an ad hoc environment, there are numerous scenarios which would benefit from geocast communication (e.g., to broadcast emergency information within a mile radius of a fire or to broadcast a coupon for coffee within a block of a Starbucks). In this paper, we classify current geocast routing protocols into two categories: data-transmission oriented protocols and routingcreation oriented protocols. We present three protocols that forward data packets to a geocast region using different techniques: the Location-Based Multicast algorithm (LBM), Voronoi diagram based geocasting and a protocol called GeoGRID. We also present two protocols that create routes to send data packets to a geocast region: GeoTORA (a protocol which is the combination of the unicast protocol Temporally-Ordered Routing Algorithm and flooding in a geocast region) and a Mesh-based Geocast Routing Protocol. We present the details of these five geocast protocols in this paper.