Geo-Cast Routing Protocol
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The document discusses geo-cast routing protocols, which deliver data packets to nodes within a specified geographic region. It describes two categories of geo-cast protocols: data-transmission oriented protocols, which focus on transmitting information from source to geographic region, and routing creation oriented protocols, which aim to reduce flooding overhead while maintaining delivery accuracy. Specific protocols discussed include Location-Based Multicast, Geo-GRID, Geo-TORA, and mesh-based geo-cast routing. The document concludes by noting open issues like scalability, applications, addressing, and security for geo-cast routing over mobile ad hoc networks.
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Geo-Cast Routing Protocol
- 2. Geo-Cast Routing Protocol Aims at delivering data packets to a group of nodes located in a specified geographical area Can be seen as a variant of the conventional multicasting problem, and distinguishes itself by specifying hosts as group members within a specified geographical region
- 3. Geo-casting Group members are within a specified geographical region. Whenever a node in the geo-cast region receives a geo-cast packet, it floods the geo-cast packet to all its neighbors. A geo-cast protocol works if at least one node in the geo-cast region receives the geo-cast packet. Protocols use a jitter technique in order to avoid two packets colliding with each other by a broadcast. Existing geo-cast protocols divided into two categories: data-transmission oriented protocols routing creation oriented protocols The difference is how they transmit information from a source to one or more nodes in the geo-cast region
- 4. Data-Transmission Oriented Geo-cast Routing Protocols Location-Based Multicast Extends the LAR unicast routing algorithm for geo-casting. Utilize location information to improve the performance of a unicast routing protocol The goal is to decrease delivery overhead of geo-cast packets by reducing the forwarding space for geo-cast packets, while maintaining accuracy of data delivery The algorithm is based upon a flooding approach while a node determines whether to forward a geo-cast packet further via one of two schemes
- 5. LBM Scheme 1 A node receives a geo-cast packet, it forwards the packet to its neighbors if it is within a forwarding zone The size of the forwarding zone depends on (i) the size of the geocast region (ii) the location of the sender Box forwarding zone: Rectangle covering source and the forwarding zone
- 6. LBM Scheme 2 The distance between S and D is DISTs S includes DISTs and (Xc, Yc) in route request message When node I receives route request Calculates its distance to D (DISTa) If DISTs+δ DISTa then forwards the request and replace DISTs by DISTi Otherwise, node I discards the route request 1. δ is a parameter for increasing the probability of finding a route or dealing with location error 2. The request is forwarded closer and closer to destination D
- 7. Voronoi Diagram The Voronoi diagram partitions the area in to a set of convex polygons such that all polygon edges are equidistance.
- 8. Geo-GRID Geo-GRID protocol uses location information in defining forwarding zone and elects a special host in each grid area responsible for forwarding geocast packets The forwarding zone in LBM incurs unnecessary packet transmissions A tree-based solution is prohibitive in terms of control overhead Geo-GRID partitions the geographic area into two-dimensional logical grids of size d X d Two schemes on how to send geo-cast packets in Geo-GRID: Flooding-Based Geo-GRID Tree-Based Geo-GRID.
- 9. Flooding-Based Geo-GRID Only gateways in every grid within the forwarding zone rebroadcast the received Geo-cast packets
- 10. Route Creation Oriented Geo-TORA: Reduce the overhead of transmitting geo-cast packets via flooding techniques, while maintaining high Accuracy. Mesh based Geo-cast Routing Protocol: Uses a mesh for geo-casting to provide redundant paths between source and group members
- 11. Conclusions and Future Directions Scalability Applications for broadcast, multicast, and geo-cast over MANETs Address configuration Security
Editor's Notes
- the concept of geocasting was introduced by Imielinski and Navas
- They also presented an architecture to implement geocasting in the internet. Ko and Vaidya [8] presented the so-called Location-Based Multicast (LBM) algorithm that uses flooding to deliver a geocast packet. However, to reduce propagation of the flood, LBM limits the flood to a forwarding zone – the forwarding zone covers a subset of the network, and is determined based on the location of the sender and coordinates of the geocast region. Although the algorithm in [8] is able to limit the flood of geocast packets to a relatively small region, still many nodes outside the geocast region tend to receive the geocast packet.
- The schemes for multicasting can be broadly divided into two types: flooding-based schemes and treebased schemes. Both approaches have their advantages and disadvantages. Flooding-based schemes do not need to maintain as much network state as the tree-based protocols. On the other hand, flooding-based schemes can potentially deliver the multicast packets to a large number of nodes who do not wish to receive them (i.e., nodes which do not belong to the multicast group). Tree-based schemes tend to avoid this drawback of flooding-based schemes, at the cost of increased overhead in tree maintenance.
- TORA (Temporally Ordered Routing Algorithm) is one of a family of link reversal algorithms [3] for routing in ad hoc networks. For each possible destination in the ad hoc network, TORA maintains a destination-oriented directed acyclic graph (DAG). In this graph structure, starting from any node, if links are followed in their logical direction, the path leads to the intended destination. TORA uses the notion of heights to determine the direction of each link – we will discuss this in greater detail later. Despite dynamic link failures, TORA attempts to maintain the destinationoriented DAG such that each node can reach the destination, as illustrated below.