Overhead-controlled contention-based routing for VANETs

Routing of VANETs is a challenging issue that has attracted many attentions of researchers recently. Contention based routing protocols have good congruity with high mobility of nodes in this kind of networks. Prevention from forwarding duplicate packets is an important challenge in such routing protocols. Indeed, such duplications can reduce scalability and efficiency of contention based routing protocols. On the other hand, the prevention method can affect advantages of such routing protocols. In this paper, we proposed 2 new routing protocols by adding 2 new methods to an existing contention based routing protocol to decrease overhead of duplications. Simulation results show that overhead decreases significantly while preserving end-to-end delay and delivery ratio in suitable values

DIRECTIONAL ANTENNA BASED EFFICIENT LOCATION AWARE ROUTING IN MOBILE ADHOC NETWORK

Mobile Adhoc Network (MANET) also called as wireless ad hoc network is a self-organizing, self-configuring infrastructure less network containing a group of mobile nodes communicating wirelessly. As the hosts move often resulting in dynamic topology of the network, routing seeks more attention. Therefore, routing protocol using node’s location information like LAR (location aided routing) has emerged as potential solution. Here, the route discovery is limited to a small region named as request zone in contrast to blind flooding over the entire network. Also it is noticeable that the shape and size of the request zone play a vital role in enhancing the protocol’s performance. After various analyses it was concluded that for higher node density, elliptical shaped request zone performs better than other possible shapes. Further, suitable route must be chosen based on current load status of the network so that successful delivery of packets is ensured. Generally, omni-directional antennas are used for communication between moving motes. The disadvantage of mobile ad hoc networks with omni-directional antenna lies in the limited capacity caused by high interference and low spatial reuse. This paper focuses on obtaining optimal size for request zone in accordance with varying node density. Further, optimal path between source and destination is selected using Dijkstra’s algorithm. Our simulation results show that directional antennas outshines the performance of omni-directional antennas in increasing transmission range of nodes, reducing the number of redundant nodes involving in data communication etc

Modeling and Analysis of Location Service Management in Vehicular Ad Hoc Networks

Recent technological advances in wireless communication and the pervasiveness of various wireless communication devices have offered novel and promising solutions to enable vehicles to communicate with each other, establishing a decentralized communication system. An emerging solution in this area is the Vehicular Ad Hoc Networks (VANETs), in which vehicles cooperate in receiving and delivering messages to each other. VANETs can provide a viable alternative in situations where existing infrastructure communication systems become overloaded, fail (due for instance to natural disaster), or inconvenient to use. Nevertheless, the success of VANETs revolves around a number of key elements, an important one of which is the way messages are routed between sources and destinations. Without an effective message routing strategy VANETs' success will continue to be limited. In order for messages to be routed to a destination effectively, the location of the destination must be determined. Since vehicles move in relatively fast and in a random manner, determining the location (hence the optimal message routing path) of (to) the destination vehicle constitutes a major challenge. Recent approaches for tackling this challenge have resulted in a number of Location Service Management Protocols. Though these protocols have demonstrated good potential, they still suffer from a number of impediments, including, signaling volume (particularly in large scale VANETs), inability to deal with network voids and inability to leverage locality for communication between the network nodes. In this thesis, a Region-based Location Service Management Protocol (RLSMP) is proposed. The protocol is a self-organizing framework that uses message aggregation and geographical clustering to minimize the volume of signalling overhead. To the best of my knowledge, RLSMP is the first protocol that uses message aggregation in both updating and querying, and as such it promises scalability, locality awareness, and fault tolerance. Location service management further addresses the issue of routing location updating and querying messages. Updating and querying messages should be exchanged between the network nodes and the location servers with minimum delay. This necessity introduces a persuasive need to support Quality of Service (QoS) routing in VANETs. To mitigate the QoS routing challenge in VANETs, the thesis proposes an Adaptive Message Routing (AMR) protocol that utilizes the network's local topology information in order to find the route with minimum end-to-end delay, while maintaining the required thresholds for connectivity probability and hop count. The QoS routing problem is formulated as a constrained optimization problem for which a genetic algorithm is proposed. The thesis presents experiments to validate the proposed protocol and test its performance under various network conditions

Proposal and Analysis of Region-based Location Service Management Protocol for VANETs

International audienceOne of the major challenges for vehicular ad hoc networks (VANETs) is related to efficient location management issue. In this paper, we propose a new region-based location service management protocol (RLSMP) that uses mobility patterns as means to synthesize vehicle movement and thus can be used in VANETs applications. One of the key distinguishing features of our solution from existing literature is its scalability since it uses message aggregation in both updating and querying, and promises locality awareness as well as minimum signaling overhead. To evaluate the efficiency of our proposal, we compare our scheme with existing solutions using both analytical and simulation approaches. To achieve this, we develop analytical models to evaluate the location updates cost. Numerical and simulation results show that our protocol scales better than existing schemes, when increasing the size of VANET which enhances the feasibility of such large scale ad hoc networks