Location Aware Data Aggregation for Efficient Message Dissemination in Vehicular Ad Hoc Networks

An intelligent location-aware data aggregation mechanism for real-time observation, estimation, and efficient dissemination of any kind of traffic information in vehicular ad hoc networks (VANETs) is presented in this paper. The mechanism introduces a location awareness algorithm, enabling spatiotemporal database indexing and providing the location context of the messages without the use of advanced positioning systems such as satellite navigation and digital maps. Intelligent passive clustering and adaptive broadcasting are used to minimize the number of messages exchanged, packet collisions, and network load. The incoming messages are fused by a Kalman filter, allowing the description of the traffic-related information as a system characterized by as many variables as needed, depending on the application design. The scheme allows the comparison of aggregates and single observations, which enables their merging and better overall accuracy. Old information in aggregates is removed by real-time database refreshing, thus leaving only newer relevant information for the driver to make real-time decisions in traffic. The mechanism is generic and can be used for any kind of VANET information. It is evaluated by extensive simulations to show the efficiency and accuracy

Reliable and efficient data dissemination schemein VANET: a review

Vehicular ad-hoc network (VANET), identified as a mobile ad hoc network MANETs with several added constraints. Basically, in VANETs, the network is established on the fly based on the availability of vehicles on roads and supporting infrastructures along the roads, such as base stations. Vehicles and road-side infrastructures are required to provide communication facilities, particularly when enough vehicles are not available on the roads for effective communication. VANETs are crucial for providing a wide range of safety and non-safety applications to road users. However, the specific fundamental problem in VANET is the challenge of creating effective communication between two fast-moving vehicles. Therefore, message routing is an issue for many safety and non-safety of VANETs applications. The challenge in designing a robust but reliable message dissemination technique is primarily due to the stringent QoS requirements of the VANETs safety applications. This paper investigated various methods and conducted literature on an idea to develop a model for efficient and reliable message dissemination routing techniques in VANET

Reliable and enhanced cooperative cross-layer medium access control scheme for vehicular communication

In an unreliable cluster-based, broadcast vehicular network setting, we investigate the transmission reliability and throughput performance of random network coding (RNC) as a function of the percentage of packet generation rate and transmit power to noise ratio. In the paper, a novel scheme called reliable and efficient cooperative cross-layer MAC (RECMAC) is proposed. The proposed scheme consists of a source vehicle broadcasting packets to a set of receivers (i.e. one-to-many) over independent broadcast erasure channels. The source vehicle performs RNC on N packets and broadcasts the encoded message to a set of receivers. In each hop, several vehicles form a cluster and cooperatively transmit the encoded or re-encoded packet. The combination of RNC, cluster based, and cooperative communications enables RECMAC to optimally minimize data redundancy, which means less overhead, and improve reliability as opposed to coding-based solutions. Theoretical analyses and simulation results show that under the same conditions RECMAC scheme can achieve improved performance in terms of transmission reliability and throughput

Performance comparison of a platooning scenorio using the IEEE 802.11p

There has been much technological advancement in the wireless communic ation in the recent past for the intelligent transportation systems among all Dedicated Short - Range Communication or DSRC or Wireless Access for Vehicular Environment (WAVE) has very important role for the autonomous connected vehicles. It is well known fo r its support for the time sensitive safety applications. Along with safety application, the service to provide nonsafety applications is also becoming very popular, these nonsafety applications may include infotainment, electronic toll tax collection and traffic control to name a few. DSRC protocol consists of WAVE Short Messaging Protocol or WSMP which aims to provide real time safety application and it is also able to support some nonsafety related applications. In our dissertation we aim to evaluate the performance of IEEE 802.11p standard for both safety and nonsafety messages. Our sce norio for master thseis consists of fleet of vehicles that are moving with constant speed and in the same direction forming the platoon pattern. The distance between ever y two vehicles is set to be constant and it is kept 200 meters, similarly every vehicle is moving with constant speed of 20 m/sec. To develop the scenorio for Basic Safety Messages, each vehicle is able to generate BSM messages periodically and it fixed pa yload size of 200 bytes and data rate of 6 Mbits/sec. For the nonsafety messages we also compare the perfor m ance of existing protocols such as optimized link state routing OLSR protocol and Ad - hoc O n - demand Routing AODV protocol, the packet size is kept 25 6 bytes at 8 kbps. We have used the metrics such as throughput, packet delivery ratio , packet loss ratio and end to end delay for evaluaing the performance of as optimized link state routing OLSR protocol and Ad - hoc On - demand Routing AODV protocols Our si mulation results conducted in Network Simulator NS - 3 show that WSMP protocol have adequate level of packet delivery ratio and throughput with moderate level of packet loss at lower intervehicle distances and higher packet loss ratio at greater distances be tween the vehicles. On the same way, when the simulation results of as optimized link state routing OLSR protocol and Ad - hoc On - demand Routing AODV protocol are compared it is evident that AODV protocol better performs in terms of throughput, packet deliv ery ratio as well as in terms of packets loss, but AODV protocol being reactive in nature, assumes much higher end to end delay for the packet delivery

Current paradigms in intelligent transportation systems

Intelligent transportation systems (ITS) constitute today a multidisciplinary field of study involving a large number of different research areas. As a consequence, it is difficult to achieve a structured view of ITS, which is necessary to unify efforts and as guidance for future developments. This study aims to identify the main paradigms in the field of ITS by semantically analysing studies related to this general topic. An understanding about which research is considered valuable by the research community to build upon may provide valuable insights in this field. As a result of the statistical treatment of data, up to 13 paradigms are obtained. The scope of these paradigms and the relationships between them have also been detailed, providing a structured vision of ITS synthesised in a map formMinisterio de Educación y Ciencia DPI2007- 60128Junta de Andalucía. Consejería de Innovación, Ciencia y Empresa P07-TIC-0262

Efficient channel allocation and medium access organization algorithms for vehicular networking

Due to the limited bandwidth available for Vehicular Ad-hoc Networks (VANETs), organizing the wireless channel access to efficiently use the bandwidth is one of the main challenges in VANET. In this dissertation, we focus on channel allocation and media access organization for Vehicle-to-Roadside Units (V2R) and Vehicle-to-Vehicle (V2V) communications. An efficient channel allocation algorithm for Roadside Unit (RSU) access is proposed. The goal of the algorithm is to increase system throughput by admitting more tasks (vehicles) and at the same time reduce the risk of the admitted tasks. The algorithm admits the new requests only when their requirements can be fulfilled and all in-session tasks\u27 requirements are also guaranteed. The algorithm calculates the expected task finish time for the tasks, but allocates a virtual transmission plan for the tasks as they progress toward the edges of the RSU range. For V2V mode, we propose an efficient medium access organization method based on VANETs\u27 clustering schemes. In order to make this method efficient in rapid topology change environment like VANET, it\u27s important to make the network topology less dynamic by forming local strongly connected clustering structure, which leads to a stable network topology on the global scale. We propose an efficient cluster formation algorithm that takes vehicles\u27 mobility into account for cluster formation. The results of the proposed methods show that the wireless channel utilization and the network stability are significantly improved compared to the existing methods

Connected Vehicle Technology: User and System Performance Characteristics

The emerging connected vehicle (CV) technology plays a promising role in providing more operable and safer transportation environments. Yet, many questions remain unanswered as to how various user and system characteristics of CV-enabled networks can shape the successful implementation of the technology to maximize the return on investment. This research attempts to capture the effect of multiple factors such as traffic density, market penetration, and transmission range on the communication stability and overall network performance by developing a new CONnectivity ROBustness (CONROB) model. The model was tested with data collected from microscopic simulation of a 195 sq-mile traffic network and showed a potential to capture the effect of such factors on the communication stability in CV environments. The information exchanged among CVs can also be used to estimate traffic conditions in real time by invoking the probe vehicle feature of CV technology. Since factors affecting the connectivity robustness also have an impact on the performance of traffic condition estimation models, a direct relationship between connectivity robustness and traffic condition estimation performance was established. Simulation results show that the CONROB model can be used as a tool to predict the accuracy of the estimated traffic conditions (e.g. travel times), as well as the reliability of such estimates, given specific system characteristics. The optimal deployment of road-side units (RSUs) is another important factor that affects the communication stability and the traffic conditions estimates and reliability. Thus, an optimization approach was developed to identify the optimal RSUs locations with the objective function of maximizing the connectivity robustness. Simulation results for the developed approach show that CONROB model can help identify the optimal RSUs locations. This shows the importance of CONROB model as a planning tool for CV environments. For the individual user performance characteristics, a preliminary driving simulator test bed for CV technology was developed and tested on thirty licensed drivers. Forward collision warning messages were delivered to drivers when predefined time-to-collision values take place. The findings show improved reaction times of drivers when receiving the warning messages which lend credence to the safety benefits of the CV technology