In this environment, the road network is fragmented into cells such that nodes in a cell can communicate with any node within a two cell distance. In this paper, we introduce an efficient broadcast technique, called CB-S (Cell Broadcast for Streets), for vehicular networks with occlusions such as skyscrapers. Vehicular networks are a promising application of mobile ad hoc networks. Our simulation results show the Communication Path approach can achieve several times better performance than traditional approach based on a fixed sequence of physical links. Since a path can be supported by many alternative nodes, this scheme is much less susceptible to node mobility. These physical nodes take turns in forwarding data packets for the path. The routing functionality of a communication path is provided by the physical nodes (i.e., mobile devices) currently within the geographical region served by the path. A communication path is a dynamically-created geographical area that connects the source and destination nodes. To address this limitation, we introduce the Communication Path abstraction in this paper. Although a new communication route can be established when a break in the communication path occurs, repeatedly reestablishing new routes incurs delay and substantial overhead. Communication links of an established communication path that extends between source and destination nodes are often broken under a high mobility environment. Supporting high mobility is essential to mobile ad hoc networks in a wide range of emerging applications such as vehicular networks.
#1 HOP 2 HOP SIMULATOR#
The results from the per-formance evaluation in network simulator (ns-2.33) shows that our scheme shows high reliability over 90% of data de-livery ratio, low-latency and better overhead compared to the existing routing protocols. Moreover, we propose two reliability metrics for the grid-based protocol based on packet delivery rate between the cells and the sta-tus of the mobile nodes that enables relay node selection in the cell for forwarding data.
Meanwhile, a large-cell can be used to allow the probability of seamless data forwarding when the network is sparse. In a dense network, a small-cell grid is employed to serve more alternative cells for a path.
Our routing proto-col for tactical MANETs employs multi-grid routing scheme adaptively uses varying cell sizes, unlike single-grid based protocols. In grid-based proto-cols, deployment region is divided into small patches called 'cells,' which are the units of routing. We propose a reliable multi-grid based routing protocol with the purpose of attaining high percentage of data delivery in the tactical mobile ad hoc networks. By simulation results, we show that our proposed algorithm achieves good delivery ratio with less forwarding and control overhead. This algorithm reduces the average retransmission redundancy, avoids both the broadcast storm problem and the ACK implosion problem, recovers the transmission error locally and increases the broadcast delivery ratio.
#1 HOP 2 HOP FULL#
Moreover, a NACK mechanism is used to provide full reliability for all non forwarding nodes. The retransmissions of the forwarding nodes are overheard by the sender as the confirmation of their reception of the packet. In this algorithm, the broadcasting nodes select a subset of their neighbors to forward the message using an efficient forward node selection mechanism. In this paper, we propose to develop a reliable broadcasting algorithm which is a sender-based algorithm. All the current routing protocols depend upon the easier form of broadcasting called flooding which can result in high broadcast redundancy and packet collisions. To demonstrate the improvement, we present extensive simulation results to show the proposed techniques can prevent the occurrence of contention areas and significantly outperform existing techniques.ĭue to the broadcasting nature of radio transmission, the most fundamental task in MANETs is the broadcast operation. In this paper, we propose a congestion avoidance routing (CAR) technique for two greedy protocols, connectionless approach (CLA) and contention-based forwarding (CBF), to address the packet loss problem by rerouting packets dynamically to avoid traffic congestion. However, the greedy approach suffers from packet loss because the packet forwarding policy does not consider traffic congestion along the route or the direction. For high mobility environments, greedy techniques rely on any mobile hosts along the general direction of the destination node to forward data packets. Early solutions focused reconnecting a broken link quickly with a low overhead however, this strategy cannot cope with a high mobility environment. In a mobile ad hoc network (MANET), communication connections need to adapt to frequent and unpredictable topology changes.
0 kommentar(er)
