In this paper, we propose a multihop broadcast protocol for dissemination of time-critical emergency messages (EMs) in vehicular ad hoc networks (VANETs), where the IEEE 802.11p technology is used for communication among the nodes. The proposed trinary partitioned black-burst-based broadcast protocol (3P3B) consists of two primary mechanisms. First, a mini distributed interframe space (DIFS) in a medium access control (MAC) sublayer is introduced to give the time-critical EMs a higher access priority to the communication channel compared with other messages. Second, a trinary partitioning is designed to iteratively partition the communication range into small sectors. The trinary partitioning mechanism allows the farthest possible vehicle in the farthest sector from the sender node to perform forwarding to increase the dissemination speed by reducing the number of forwarding hops. In addition, 3P3B reduces the contention period jitter, which is independent of the density of vehicles, resulting in a more stable contention period. Analytical models are proposed for performance evaluation in conjunction with simulation-based performance analysis. The results demonstrate that 3P3B outperforms benchmarks of the existing broadcast protocols in VANETs in terms of the average message dissemination speed, message progress, communication delay, and packet delivery ratio.

Trinary Partitioned Black-Burst-Based Broadcast Protocol for Time-Critical Emergency Message Dissemination in VANETs

With the advancement of wireless sensor networks (WSNs) and technology, applicability of WSNs as a system is touching new heights. The development of multimedia nodes has led to the creation of another intelligent distributed system, which can transfer real-time multimedia traffic, ubiquitously. Wireless multimedia sensor networks (WMSNs) are applicable in a wide range of areas including area monitoring and video surveillance. But due to unreliable error-prone communication medium and application specific quality of service (QoS) requirements, routing of real-time multimedia traffic in WMSNs poses a serious problem. The paper discusses various existing routing strategies in WMSNs, with their properties and limitations which lead to open research issues. Further, detailed classification and analytical comparison of discussed protocols are also presented.

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Routing in Wireless Multimedia Sensor Networks: A Survey of Existing Protocols and Open Research Issues

Based on the rapid growth in the applications of Unmanned Aerial Vehicles (UAVs) in the last decade, the idea of in-flight communication among UAVs has been proposed in cooperative missions. Since medium and small sized UAVs are cheap and deployable, several of them can be used to form what we call an Unmanned Aeronautical Ad-hoc Networks (UAANETs). Due to the availability of location information, geographic protocols can be an option for routing in UAANETs. Although we show that greedy geographic forwarding alone is not sufficient in UAANETs, our results illustrate that a combination of greedy geographic forwarding with a reactive mechanism, which forms a ReactiveGreedy-Reactive (RGR) routing, can be beneficial. Simulation results show that RGR outperforms existing protocols such as Ad-hoc On-demand Distance Vector (AODV), and greedy geographic forwarding in searching missions in terms of delay and packet delivery ratio while its overhead is comparable with traditional mechanisms.

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Reactive-Greedy-Reactive in Unmanned Aeronautical Ad-hoc Networks: A Combinational Routing Mechanism

In an effort to provide QoS in VANET, the IEEE 802.11p physical layer, which is recommended as VANET MAC protocol experiences a huge amount of packet losses as a result of collisions. Its performance can be improved by using Time Division Multiple Access (TDMA) scheme to attain restructuring of TDMA slots with no central control. In this paper, we intend to propose a QoS routing protocol capable of finding and establishing a path through clustering approach using TDMA. This, however, is achieved by calculating the corresponding QoS provision values based on QoS metrics before selecting the optimal, reliable and stable route between source, cluster head and destination. The protocol would be an extension of LORA-CBF, to which QoS features are embedded in the route request selection. The results obtained through NCTUns simulator are used for analysis of throughput for both UDP and TCP traffic classes.

A QoS approach for cluster-based routing in VANETS using TDMA scheme

This paper presents a Priority based Routing Protocol (PRP) in Vehicular Ad hoc Network (VANET), according to message types. We focus mainly on a safety messaging application for safe driving in distributed environment, i.e., ad hoc manner. Broadcast based routing protocol is proposed along with priority and position enhancement to provide i) fully distributed routing protocol, ii) different quality of services (QoS) for different types of messages, iii) maximum message dissemination distance per hop. The proposed protocol, PRP, is evaluated using simulation software called OMNeT++. The performance parameters include average MAC delay, percentage of message reception and collision, as well as average message dissemination distance per hop. The results show the PRP achieves both message prioritization and maximum dissemination distance in fully distributed environment.

Priority based Routing Protocol in Vehicular Ad hoc Network

Several geographic routing protocols using location information have already been proposed for ad hoc networks in order to improve performance of ad hoc routing protocols. Here we can mention the case of Greedy Perimeter Stateless Routing (GPSR) protocol. GPSR makes greedy forwarding decisions using merely information about a router’s immediate neighbors in the network topology. In case a packet reaches a region where greedy forwarding is impossible, the algorithm recovers by routing around the perimeter of the region. This paper presents the performance evaluation of GPSR protocol for its qualities of scaling and its good performance even at high mobility. We simulated the protocol by using the Hierarchical Location Service (HLS) which is purely geographical in its strategy for selecting and updating the location servers. The performance evaluation is based mainly on three network metrics: Packet Delivery Ratio (PDR), Traffic Overhead (TOH) and End to End Delay (EED). We have focused on the variation effects of a network parameters set such as: the number of mobile nodes, the network load, speed nodes and inter-beacon interval.

Refaat Elidoudi

Papers

Performance Evaluation of Greedy Perimeter Stateless Routing Protocol in Ad Hoc Networks