A Novel Cross-layer Communication Protocol for Vehicular Sensor Networks

Communication protocols in Vehicular Sensor Networks (VSNs) in urban areas play an important role in intelligent transport systems applications. Many cross layer communication protocols studies are originated from topology-based algorithms, which is not suitable for the frequently-changing computational scenario. In addition, the influence factors that have been considered for VSNs routing are not enough. With these aspects in mind, this paper proposes a multi-factor cross layer position-based routing (MCLPR) protocol for VSNs to improve reliability and efficiency in message delivery. Considering the complex intersection environment, the algorithm for vehicles selection at intersections (called AVSI) is further proposed, in which comprehensive factors are taken into account including the position and direction of vehicle, the vehicle density, the signal-to-noise-plus-interference ratio (SNIR), as well as the frame error rate (FER) in MAC layer. Meanwhile, the dynamic HELLO STREAM broadcasting system with the various vehicle speeds is proposed to increase the decisions accuracy. Experimental results in Network Simulator 3 (NS-3) show the advantage of MCLPR protocol over traditional state-of the-art algorithms in terms of packet delivery ratio (PDR), overhead and the mean end-to-end delay

VANET-enabled eco-friendly road characteristics-aware routing for vehicular traffic

There is growing awareness of the dangers of climate change caused by greenhouse gases. In the coming decades this could result in numerous disasters such as heat-waves, flooding and crop failures. A major contributor to the total amount of greenhouse gas emissions is the transport sector, particularly private vehicles. Traffic congestion involving private vehicles also causes a lot of wasted time and stress to commuters. At the same time new wireless technologies such as Vehicular Ad-Hoc Networks (VANETs) are being developed which could allow vehicles to communicate with each other. These could enable a number of innovative schemes to reduce traffic congestion and greenhouse gas emissions. 1) EcoTrec is a VANET-based system which allows vehicles to exchange messages regarding traffic congestion and road conditions, such as roughness and gradient. Each vehicle uses the messages it has received to build a model of nearby roads and the traffic on them. The EcoTrec Algorithm then recommends the most fuel efficient route for the vehicles to follow. 2) Time-Ants is a swarm based algorithm that considers not only the amount of cars in the spatial domain but also the amoumt in the time domain. This allows the system to build a model of the traffic congestion throughout the day. As traffic patterns are broadly similar for weekdays this gives us a good idea of what traffic will be like allowing us to route the vehicles more efficiently using the Time-Ants Algorithm. 3) Electric Vehicle enhanced Dedicated Bus Lanes (E-DBL) proposes allowing electric vehicles onto the bus lanes. Such an approach could allow a reduction in traffic congestion on the regular lanes without greatly impeding the buses. It would also encourage uptake of electric vehicles. 4) A comprehensive survey of issues associated with communication centred traffic management systems was carried out

PERFORMANCE EVALUATION OF SINGLE-HOP PERIODIC SAFETY BEACONING FOR VEHICLE-TO-VEHICLE COMMUNICATION IN V ANET

Saving human lives on road has become the prime objective of Vehicular Ad hoc Network (VANET). In order to achieve safety, vehicles maintain neighborhood awareness with the help of safety messages. Providing an efficient safety messaging mechanism is a challenging task in V ANET, due to particular characteristics of VANET, i.e. high mobility, limited channel bandwidth, very short communication duration, and highly dynamic topology. In most of the safety messaging schemes proposed so far, Periodic Safety Beacons (PSBs) are generally considered dispensable in comparison with event-driven messages. However in reality, vehicle-to-vehicle (V2V) PSBs are used to collect critical information required by all the safety messaging schemes and cannot be dispensed. Thus, ensuring optimum QoS for V2V single-hop PSBs is essential for achieving acceptable level of safety. However, thorough performance evaluation ofV2V single-hop PSBs is yet to be carried out. This research comprehensively investigates V2V single-hop periodic safety beaconing in the light of tunable parameters i.e. Beacon Generation Interval (BGI), Safety Beacon Size (SBS), and Communication Range (CR) that govern their behavior. Results from exhaustive simulations show that adjusting tunable parameters solely or combined does not fully satisfY the strict QoS criterion required for safety applications. Overall, an acceptable level of end-to-end delay can be achieved by dynamically adjusting tunable parameters with BGI > 1 OOms, but lower BGI is not suitable with larger SBS. In dense traffic conditions strict PDR criterion of 99% is never achieved beyond lOOm target CR. An exclusive comparison between tunable parameters shows that solely adjusting BGI can attain relatively higher PDR than other tunable parameters while SBS remains the least effective parameter. It is also validated that dynamic adjustment of CR and BGI is necessary for optimal output in terms of PDR. Furthermore, optimal combinations of tunable parameters for different highway service levels with respect to safety application requirements are also presented

Distributed rate control algorithm for VANETs (DRCV)

This paper presents Distributed Rate Control for VANETs (DRCV), a distributed light-weight congestion control algorithm tailored for safety messages. DRCV monitors and estimates channel load and controls the packet rate of outgoing periodic packets. A new approach called Fast Drop is adopted to promptly drop the rate of periodic packets when event-driven safety packets are detected. Simulations show the effectiveness of DRCV in increasing packet reception probabilities and achieving efficient channel usage

Design of an adaptive congestion control protocol for reliable vehicle safety communication

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