Geocasting is a subset of conventional multicasting problem. Geocasting means to deliver a message or data to a specific geographical area. Routing refers to the activities necessary to route a message in its travel from source to the destination node. The routing of a message is very important and relatively difficult problems in the context of Ad-hoc Networks because nodes are moving very fast, network load or traffic patterns, and topology of the network is dynamical changes with time. In this chapter, different geocast routing mechanisms used in both Mobile Ad-hoc Networks and Vehicular Ad-hoc Networks. The authors have shown a strong and in-depth analysis of the strengths and weaknesses of each protocol. For delivering geocast message, both the source and destination nodes use location information. The nodes determine their locations by using the Global Positioning System (GPS). They have presented a comprehensive comparative analysis of existing geocast routing protocols and proposed future direction in designing a new routing protocol addressing the problem.
Top1. Introduction
In Ad-hoc networks routing protocols primarily face difficulty in finding an appropriate route from a source node to the destination node. A node in this network frequently changes their locations because of their high mobility. This causes frequent link or connectivity breakage and fragmentation in the network. Therefore, message passing to a particular destination region becomes very difficult and challenging task. In both, Mobile and Vehicular Ad-hoc Networks (VANETs) nodes moves very fast. The node movement depends on the terrain structure. In geocast routing a message or data is delivered to a particular predefined geographical area is known as geocast region. The method of message delivery from a particular location i.e. from source to geocast region is known as Geocasting. The main aim of geocasting is to deliver a message within reasonable time, low end-to-end delay, high accuracy i.e., high delivery success ratio, low overheads, and total number of hops be minimum. In this chapter discussed several existing routing protocols for VANETs. These protocols are Geographic Distance Routing (GEDIR)(Ruhil, LOBIYAL, & Stojmenovic, 2005), Voronoi Diagram (Stojmenovic, Ruhil, & Lobiyal, 2003),(Stojmenovic et al., 2003), Voronoi Diagram- Geographic Distance Routing (VD-GEDIR)(Ruhil et al., 2005), Most Forward Progress within Radius (MFR)(Ruhil et al., 2005), Convex Hull (Ruhil et al., 2005)(Stojmenovic et al., 2003)[10,16],Convex Hull Most Forwarding Progress Radius (CH-MFR)(Ruhil et al., 2005), Range Directional (R-DIR)(Ruhil et al., 2005), Location Aided Routing (LAR) (Y. Ko & Vaidya, 1998), Location Based Multicast (LBM) (Y. B. Ko & Vaidya, 2002), Geo Temporally Ordered Routing Algorithm (GeoTORA) (Y. B. Ko & Vaidya, 2000), Geocast Adaptive Environment Routing (GAMER) (Camp, 2003), Adaptive Handshaking- Based Geocasting protocol (AHBG) (Chen, Tseng, & Hu, 2006), GeoGRID (W. Liao, Tseng, Lo, & Sheu, 2000), Geometry Driven Geocasting protocol (GGP)(Lee & Ko, 2006). All of the above protocols may follow flooding, route based or cluster based mechanisms. These protocols are used in MANETs. In VANETs rather than these protocols the following protocols are used-Abiding Geocast (Maihoefer & Leinmueller, 2005), Stored Geocast (Maihöfer, Franz, & Eberhardt, 2003), Cached Greedy Geocast (Maihöfer, Eberhardt, & Schoch, 2004), Probabilistic methods(Yu & Heijenk, 2008), Distributed and Robust Geocast (DRG) (Joshi, 2007), Geocast Routing in Urban Vehicular Ad hoc Networks (GRUV)(Zhang et al., 2009), Intersection Area based Geocast protocol (Das & Lobiyal, 2012; Das & LOBIYAL, 2012). The performance analysis, evaluation, comparisons, reviews and surveys on various geocast protocols for MANET and VANET can be found in (Jiang & Camp, 2002; Maihöfer, 2004; Maihöfer, Cseh, Franz, & Eberhardt, 2003; Ruhil et al., 2005; Schwingenschlogl & Kosch, 2002; Yao, 2004; Yao, Krohne, & Camp, 2004). A comprehensive classification of routing protocols used in VANET is discussed in (Allal & Boudjit, 2012).