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The modification of the well known GPSR routing protocol, with the concept of lifetime is proposed. The lifetime is calculated between the node and each of its neighbors. A lifetime timer is set to the lifetime value. This timer helps in determining the quality of link and duration of the neighbor's existence. During the next hop selection process, the node selects the neighbor which is closest to the destination with good link quality and non-zero lifetime timer value in contrast to GPSR. This results in appropriate selection of the next hop node in a highly mobile and noisy environment, thus reducing the packet loss. The simulation is conducted for two scenarios where the source and destination are travelling in same and opposite directions. The results showed that GPSR with Lifetime achieved 20% to 40% increase in the packet delivery rate and significant improvement in packet delivery ratio for different "HELLO" message intervals when compared to GPSR.

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In this paper, we study the problem offinding the Origin-Destination (0-0) shortest path in intermodal transportation networks, aiming at minimizing the travel time. The transportation network and the corresponding data are modeled by means of a multi-label graph. The intermodal shortest path problem and its definition are briefly described. The algorithm developed to find the path is presented, especially by detailing o label correcting approach that updotes some labels associated with the graph nodes. The implementafion of this approach and the results it provides show its va1idiQ.

The location service is an important component of position-based routing protocols, used for VANETs. A hierarchical structured location service called Map Based Location Service (MBLS) is proposed in this paper. The MBLS exploits navigation system by using Geographical Data File (GDF) from the digital-map database to recruit location servers and to send location updates. Simulation results show that MBLS can achieve higher location query success ratio with lower location update and query cost. Further, the accuracy level of the position information in the reply message to the actual position of the mobile node is less than 50m.