Urban Vehicular Ad Hoc Networks Research Articles

Fire Controlling Under Uncertainty in Urban Region Using Smart Vehicular Ad hoc Network

Every year thousands of urban and industrial fires occur, which leads to the destruction of infrastructure, buildings, and loss of lives. One of the reasons behind this is the delayed transmission of information to the fire station and the nearer hospitals for ambulance service as the transmission of information is dependent on observer at the location where the fire is caught and cellular network. This paper proposed an automated routing protocol for the urban vehicular ad-hoc network to send the information from the location where the fire is caught to the nearest fire stations and hospitals with optimum service time. This transmission of information involves Road Side Unit (RSU) at the junction and the vehicles present in the transmission path. Selection of route to transmit faulty vehicle information from the RSU to the required faulty vehicle is based on a parameter called path value. The computation of path value is done by the attributes such as expected End To End (E2E) delay, the shortest distance to destination, the density of vehicle between the junctions, and attenuation. From the current junction, the selection of the next junction is based on minimum path value. The proposed routing protocol considers the performance parameters such as E2E delay, total service time (TST), number of network fragments or network gaps, number of hops, and attenuation for the propagation path for the evaluation of the proposed methodology. The proposed routing algorithm is implemented through OmNet++ and SUMO. Results obtained for the proposed routing protocol is compared with three existing VANET protocols (GSR, A-STAR, and ARP) in terms of End To End delay, number of hops, number of vehicular gaps, and Total Service Time (TST).

Fuzzy-based beaconless probabilistic broadcasting for information dissemination in urban VANET

Multi-hop broadcasting in Vehicular Ad Hoc Network (VANET) is the basic building block for renovating on-road travel experiences because it supports message dissemination among a large number of travelers in real-time. In order to make forwarding decisions, 1-hop neighbor table is suggested to be maintained at each vehicle by exchanging beacon packets on a periodic basis. However, a network crowded with both data packets and beacons gives rise to broadcast storms, resulting in insignificant resource consumption. Therefore, a beaconless approach would be a better solution that can control packet flow throughout the network, owing to minimizing packet collision and drop rate. Some recent literature that does not rely on beacon information broadcasts ample amounts of data packets, promoting wastage of bandwidth. To handle such issues, a Fuzzy-based Beaconless Probabilistic Broadcasting Algorithms (FBBPA) is proposed to notify vehicles about an event in less broadcasting. It is a receiver oriented broadcast suppression technique, where the forwarding probability of the packets in vehicles’ buffer is decided on the basis of their distance, angular orientation, movement direction and buffer load delay. The resultant probability is used to reschedule the packet. Among all the packets in the vehicle's buffer, the one having the highest priority at an instant is broadcasted first. For accident and advertisement packets, the analysis through simulation reveals that the proposed algorithm outperformed the compared protocols in terms of reachability (Information coverage), average delay and saved rebroadcast.

A Novel Multimodal Collaborative Drone-Assisted VANET Networking Model

Drones can be used for many assistance roles in complex communication scenarios and play as the aerial relays to support terrestrial communications. Although a great deal of emphasis has been placed on the drone-assisted networks, existing work focuses on routing protocols without fully exploiting the drones superiority and flexibility. To fill this gap, this paper proposes a collaborative communication scheme for multiple drones to assist the urban vehicular ad-hoc networks (VANETs). In this scheme, drones are distributed regarding the predicted terrestrial traffic condition in order to efficiently alleviate the inevitable problems of conventional VANETs, such as building obstacle, isolated vehicles, and uneven traffic loading. To effectively coordinate multiple drones, this issue is modeled as a multimodal optimization problem to improve the global performance on a certain space. To this end, a succinct swarm-based optimization algorithm, namely Multimodal Nomad Algorithm (MNA) is presented. This algorithm is inspired by the migratory behavior of the nomadic tribes on Mongolia grassland. Based on the floating car data of Chengdu China, extensive experiments are conducted to examine the performance of the MNA-optimized drone-assisted VANET. The results demonstrate that our scheme outperforms its counterparts in terms of hop number, packet delivery ratio, and throughput.

Link utility aware geographic routing for urban VANETs using two-hop neighbor information

Routing in Vehicular Ad Hoc Networks (VANETs) is a challenging problem. While geographic routing protocols are preferred for VANETs due to their scalability, they are focused on finding next-hop nodes closer to the destination without considering their current load or network traffic. In addition, routing decisions based on only one-hop neighbors information might be less optimal since they do not consider the availability of further suitable nodes for forwarding. Thus, such selected next-hop nodes may become overloaded with too much traffic that exceeds their available bandwidth, and may even result in significant packet losses if no other node suitable for forwarding can be found. In this paper, we propose a novel geographic routing protocol named Geo-LU. The proposed protocol improves the routing performance by extending the local view of the network topology at the current forwarder to include two-hop neighbor information. Moreover, it utilizes our proposed link utility (LU) measure. LU considers the utility of a two-hop neighbor link by considering the minimum residual bandwidth on that link and its packet loss rate. By incorporating two-hop neighbor information and our proposed LU measure, the proposed protocol, Geo-LU, can react appropriately to the increased network traffic and to the frequent topology dis-connectivity in VANETs as confirmed by our simulation results.

Relay Selection for UAV-Assisted Urban Vehicular Ad Hoc Networks

This letter investigates the relay selection problem for the air-to-ground vehicular ad hoc networks (A2G VANETs). Specifically, we use unmanned aerial vehicle (UAV) to enhance VANETs communications and network performance. For the considered network, we calculate the state transition probability (STP) of communication interruption and the transmission consumption (TC) including energy consumption and delay consumption. Afterward, we formulate the relay selection problem as a multi-objective optimization problem by jointly considering the STP and the TC. For tackling this hard problem, we simplify the primal problem by setting the STP threshold and devise a relay selection algorithm with low complexity through Q-learning. Finally, the simulation results exhibit the performance improvement of our algorithm against other schemes in terms of delivery ratio, delivery latency, and signaling overhead.

Intersection Fog-Based Distributed Routing for V2V Communication in Urban Vehicular Ad Hoc Networks

Due to the characteristics of urban vehicular ad hoc networks (VANETs), many difficulties exist when designing routing protocols. In this paper, we focus on designing an efficient routing strategy for vehicle-to-vehicle (V2V) communication in urban VANETs. Because, the characteristics of urban VANET routing performance are affected mainly by intersections, traffic lights, and traffic conditions, we propose an intersection-based distributed routing (IDR) strategy. In view of the fact that traffic lights are used to cause vehicles to stop at intersections, we propose an intersection vehicle fog (IVF) model, in which waiting vehicles dynamically form a collection or fog of vehicles at an intersection. Acting as infrastructure components, the IVFs proactively establish multihop links with adjacent intersections and analyze the traffic conditions on adjacent road segments using fuzzy logic. This approach offloads a large part of the routing work. During routing, the IVFs adjust the routing direction based on the real-time position of the destination, thus avoiding rerouting. Each time an IVF makes a distributed routing decision, the IDR model employs the ant colony optimization (ACO) algorithm to identify an optimal routing path whose connectivity is based on the traffic conditions existing in the multihop links between intersections. Because of the high connectivity of the routing path, the model requires only packet forwarding and not carrying when transmitting along the routing path, which reduces the transmission delay and increases the transmission ratio. The presented mathematical analyses and simulation results demonstrate that our proposed routing strategy is feasible and that it achieves relatively high performance.

An adaptive intersection selection mechanism using ant Colony optimization for efficient data dissemination in urban VANET

Vehicular ad-hoc network (VANET) is capable of offering a diverse set of services, and thus gains lot of attention from both academic and industrial communities. In VANET, the communicating links are prone to break easily; therefore, more attention is required to find reliable routes at a faster rate. In this context, information about connectivity and delay are valuable asset to establish and maintain a robust communication. In the proposed work, an Adaptive Intersection Selection Mechanism using Ant Colony Optimization (AISM), the problem of discovering a promising route subject to multiple Quality-of-service (QoS) constraint is emphasized. In previously reported literature, the best searched route cannot guarantee successful data packet transmission, even when it fulfills the QoS constrains at the time of discovery. To overcome this gap, AISM follows two simple strategies: Firstly, it exploits prediction-based mechanism for real time road evaluation; secondly, the route is formed between two consecutive intersections, instead of a long route between the network nodes. The connectivity and delay information obtained from small control packets called forward and backward ants are used to prioritize the candidate routes. Furthermore, by means of extensive simulation, outcomes in urban settings show that AISM outperforms the existing protocols in terms of packet delivery ratio, average delay and hop count.

RSU-Assisted Traffic-Aware Routing Based on Reinforcement Learning for Urban Vanets

In urban vehicular ad hoc networks (VANETs), the high mobility of vehicles along street roads poses daunting challenges to routing protocols and has a great impact on network performance. In addition, the frequent network partition caused by an uneven distribution of vehicles in an urban environment further places higher requirements on the routing protocols in VANETs. More importantly, the high vehicle density during the traffic peak hours and a variety of natural obstacles, such as tall buildings, other vehicles and trees, greatly increase the difficulty of protocol design for high quality communications. Considering these issues, in this paper, we introduce a novel routing protocol for urban VANETs called RSU-assisted Q-learning-based Traffic-Aware Routing (QTAR). Combining the advantages of geographic routing with the static road map information, QTAR learns the road segment traffic information based on the Q-learning algorithm. In QTAR, a routing path consists of multiple dynamically selected high reliability connection road segments that enable packets to reach their destination effectively. For packet forwarding within a road segment, distributed V2V Q-learning (Q-learning occurs between vehicles) integrated with QGGF (Q-greedy geographical forwarding) is adopted to reduce delivery delay and the effect of fast vehicle movements on path sensitivity, while distributed R2R Q-learning (Q-learning occurs between RSU units) is designed for packet forwarding at each intermediate intersection. In the case of a local optimum occurring in QGGF, SCF (store-carry-forward) is used to reduce the possibility of packet loss. Detailed simulation experimental results demonstrate that QTAR outperforms the existing traffic-aware routing protocols, in terms of 7.9% and 16.38% higher average packet delivery ratios than those of reliable traffic-aware routing (RTAR) and greedy traffic-aware routing (GyTAR) in high vehicular density scenarios and 30.96% and 46.19% lower average end-to-end delays with respect to RTAR and GyTAR in low vehicular density scenarios, respectively.

SCM: secured communication model for urban VANET applications

The primary concern of any vehicular ad hoc network (VANET) application is to offer safety and infotainment related services to commuters in a dynamic and reliable way. The characteristics of both VANET environment and the participating vehicles raise several challenges for the application development. The success of any application depends on the strength of the underlying communication model. Thus scalable, secure and robust communication models that work well with different traffic conditions and varying mobility speeds are required. We have proposed a secured communication model (SCM) for VANETs to facilitate dedicated short range communication (DSRC). The model was designed based on the specifications of IEEE 802.11p standard and the security component was offered through IDbased encryption and signature schemes. Several urban communication scenarios with different vehicle densities were created in EXata emulator. These scenarios were emulated on the proposed SCM using four routing protocols- AODV, Bellman Ford, OLSR and LAR. At higher vehicle densities the proposed model had resulted in good throughput with an acceptable delay. Out of the four routing protocols, location aided routing (LAR) protocol was found efficient on the proposed SCM.

SCM: secured communication model for urban VANET applications

The primary concern of any vehicular ad hoc network (VANET) application is to offer safety and infotainment related services to commuters in a dynamic and reliable way. The characteristics of both VANET environment and the participating vehicles raise several challenges for the application development. The success of any application depends on the strength of the underlying communication model. Thus scalable, secure and robust communication models that work well with different traffic conditions and varying mobility speeds are required. We have proposed a secured communication model (SCM) for VANETs to facilitate dedicated short range communication (DSRC). The model was designed based on the specifications of IEEE 802.11p standard and the security component was offered through IDbased encryption and signature schemes. Several urban communication scenarios with different vehicle densities were created in EXata emulator. These scenarios were emulated on the proposed SCM using four routing protocols- AODV, Bellman Ford, OLSR and LAR. At higher vehicle densities the proposed model had resulted in good throughput with an acceptable delay. Out of the four routing protocols, location aided routing (LAR) protocol was found efficient on the proposed SCM.

Parking-Area-Assisted Spider-Web Routing Protocol for Emergency Data in Urban VANET

In urban vehicular ad-hoc networks (VANET), owing to the high mobility and uneven distribution of vehicles, the rapid and reliable transmission of emergency data is a challenging task. Some bio-inspired intelligent routing protocols are effective in transmitting emergency data. However, their computational complexity and convergence speed may result in large delays. Furthermore, it has been demonstrated that parked vehicles may be used as relay nodes and thus facilitate data packet transmission in VANET. In this paper, we propose a parking-area-assisted spider-web routing protocol (PASRP) for emergency data in urban VANET. In PASRP, a spider-web transmission model is established based on the parking area by using a geographic information system and a digital map. Two control messages, request-spider and confirm-spider, are sent to obtain the transmission path from the source vehicle to the destination vehicle, and the path with the least delay is selected as the transmission path. Then, the emergency data are forwarded on the selected path using a multi-mode greedy algorithm and are prioritized by a dynamic multi-priority scheduling mechanism. Finally, the simulation results demonstrate that the proposed PASRP outperforms the existing greedy perimeter stateless routing and transmission mechanism for emergency data protocols.

Link efficiency and quality of experience aware routing protocol to improve video streaming in urban VANETs

SummaryIn a vehicular ad‐hoc network (VANET), vehicles can play an essential role in monitoring areas of a smart city by transmitting data or multimedia content of environmental circumstances like disasters or road conditions. Multimedia content communication with quality of experience (QoE) guarantees is a challenging undertaking in an environment such as that of a VANET. Indeed, a VANET is characterized by numerous varying conditions, significantly impacting its topology, quality of communication channels, and paths with respect to bandwidth, loss, and delay. This paper introduces a link efficiency and quality of experience aware routing protocol (LEQRV) to improve video streaming provisioning in urban vehicular ad‐hoc networks. LEQRV uses an enhanced greedy forwarding‐based approach to create and maintain stable high quality routes for video streaming delivery. It improves the performance of the quality of experience by increasing the achieved QoE scores and reducing the forwarding end‐to‐end delay and frame loss.

Reliable congestion control mechanism for safety applications in urban VANETs

In vehicular ad hoc networks (VANETs), cooperation between vehicles is needed for proper performance of safety applications. Beacons are periodically broadcasted by vehicles to inform their neighbors of their information, such that periodic beacons are one of the building blocks that enable the operation of safety applications. Safety applications have their own strict quality of service (QoS) requirements, and they require reliable and timely data communication within networks. When many vehicles are trying to broadcast within a confined area at the same time, frequent channel contention and congestion may occur. Therefore, channel congestion control mechanisms are key for reliable and efficient operation of safety applications.In this paper, an adaptive beacon generation rate (ABGR) congestion control mechanism is proposed to reduce channel congestion and contention. ABGR can dynamically adjust the beacon generation rate according to varying levels of vehicles’ density to ensure reliable and timely delivery of beacons. Inspired by the correlation between traffic density and vehicle speed, a dynamic application-level reliability assessment scheme (T-Pro) is proposed to evaluate the reliability of various safety applications at varying density. Finally, the application-level reliability of three safety applications is evaluated using the ABGR mechanism. Numerical results show that the performance of ABGR is far higher than that of the current DSRC. The application-level reliability of three safety applications exceeds 99%, even if density reaches 450 vehicles/(km*3 lanes).

Video Streaming in Urban Vehicular Environments: Junction-Aware Multipath Approach

In multipath video streaming transmission, the selection of the best vehicle for video packet forwarding considering the junction area is a challenging task due to the several diversions in the junction area. The vehicles in the junction area change direction based on the different diversions, which lead to video packet drop. In the existing works, the explicit consideration of different positions in the junction areas has not been considered for forwarding vehicle selection. To address the aforementioned challenges, a Junction-Aware vehicle selection for Multipath Video Streaming (JA-MVS) scheme has been proposed. The JA-MVS scheme considers three different cases in the junction area including the vehicle after the junction, before the junction and inside the junction area, with an evaluation of the vehicle signal strength based on the signal to interference plus noise ratio (SINR), which is based on the multipath data forwarding concept using greedy-based geographic routing. The performance of the proposed scheme is evaluated based on the Packet Loss Ratio (PLR), Structural Similarity Index (SSIM) and End-to-End Delay (E2ED) metrics. The JA-MVS is compared against two baseline schemes, Junction-Based Multipath Source Routing (JMSR) and the Adaptive Multipath geographic routing for Video Transmission (AMVT), in urban Vehicular Ad-Hoc Networks (VANETs).

MBR: A Map-Based Relaying Algorithm For Reliable Data Transmission Through Intersection in VANETs

In recent years, a number of routing protocols have been proposed for urban vehicular ad-hoc networks (VANETs). Yet, a common issue in these protocols is that the building shadow effect at intersections is not carefully considered. As a result, the performance of these routing protocols may degrade as the data transmission at the intersections can be severely affected by the building shadowing. To solve this problem, in this paper, we propose MBR, a map-based relaying algorithm in the MAC layer, to enhance the performance of the routing protocols in urban VANETs. To improve the reliability of data transmission at intersections, MBR novelly utilizes the digital map and the Geohash coding system to relay the packets (frames) in the MAC layer, and selects the optimal relay node based on the relative position of the nodes and the intersection. In this paper, we propose two versions of the algorithm: MBR-S utilizes a single IEEE 802.11p radio; and MBR utilizes a collaboration of the IEEE 802.11p channel and the Sub-1GHz channel, which has border communication range in the intersections than that of MBR-S. Both our real world experiments and extensive simulations demonstrate that MBR-S can significantly improve the performance of the state-of-the-art VANET routing protocols, which can be further enhanced with the collaboration of two channels.

High $$\hbox {CO}_2$$ zone localization in city areas using hardware implementation of urban vehicular ad hoc network (UVANET) platform

Currently, increase of $$\mathrm{CO}_2$$ emissions in the city areas is due to industrial pollution, burning of fuels, deforestation, and excessive vehicle movement. For environmental safety, regular monitoring of $$\mathrm{CO}_2$$ level is needed in the city areas. The main objective of this research is to localize the high $$\mathrm{CO}_2$$ zones in the city areas using UVANETs. Vehicles in the city areas are used as the resources to collect and monitor the $$\mathrm{CO}_2$$ levels. After the zone localization, the location (high $$\mathrm{CO}_2$$ zone) information is sent to the information center using the proposed routing scheme through the vehicles to take possible actions in emergency. To the best of our knowledge no such work has been proposed to localize the high $$\mathrm{CO}_2$$ zones in the city areas using UVANETs. For performance evaluation, this method is tested in a small UVANET prototype developed in indoor environment.

Efficient data dissemination protocol based on complex networks\u2019 metrics for urban vehicular networks

Services that aim to make the current transportation system more secure, sustainable, and efficient constitute the Traffic Management Systems (TMS). Vehicular Ad hoc Networks (VANETs) exert a strong influence for TMS applications, due to TMS services require data, communication, and processing for operation. Besides, VANET allows direct communication between vehicles, and data are exchanged and processed between them. Several TMS services require disseminated information among decision-making vehicles. However, such dissemination is a challenging task, due to the specific characteristics of VANETs, such as short-range communication and high node mobility, resulting in several variations in their topology. In this article, we introduce an extensive analysis of our proposed data dissemination protocol based on complex networks’ metrics for urban VANET scenarios, called DDRX. Each vehicle must build a subgraph to identify the relay node to continue the dissemination process. Based on the local graph, it is possible to select the relay nodes based on complex networks’ metrics. Simulation results show that DDRX offers high efficiency in terms of coverage, number of transmitted packets, delay, and packet collisions compared to well-known data dissemination protocols. Also, DDRX provides significant improvements to a TMS that needs efficient data dissemination.

MMIR: a microscopic mechanism for street selection based on intersection records in urban VANET routing

In urban vehicular ad hoc networks (VANETs), the intersection-based routing scheme has represented its greater applicability and better efficiency to adapt to high and constrained mobility. How to make an accurate decision for street selection is a challenging issue due to the rapid topology changes in VANETs. In this paper, we propose a microscopic mechanism based on intersection records (MMIR) in which the intersection vehicle nodes maintain and update a records table with every passing vehicle’s individual information. By analyzing and processing these entries, we evaluate these vehicles’ current positions so as to compute the connectivity probability or estimated delivery delay for all candidate streets to support street selection. In contrast to the statistical and macroscopic information for the common condition, we firstly make use of the individual and microscopic data to enhance the accuracy of estimated results. Furthermore, according to the quantity and the running interval, we classify vehicles into two categories: individual and queue vehicles, in order to effectively decrease the complexity of position estimation. Lastly, since there are no dedicated control packets generated in MMIR, the network overhead is low. The simulation results show that the proposed MMIR outperforms existing approaches of street selection in terms of the accuracy of computed connectivity probability and estimated delay.

A stable clustering algorithm using the traffic regularity of buses in urban VANET scenarios

Vehicular ad-hoc networks (VANETs) use clustering to manage data dissemination among vehicles. However, the high dynamic mobility of vehicles can lead to frequent re-clustering and decreased cluster stability. In previous work, cluster heads are selected generally based on mobility characteristics of vehicles, failing to take into account spatial and temporal dependency. Several studies have proposed cluster management mechanisms that increase cluster stability. However, in doing so these mechanisms generate excessive communication packets. In this paper, we propose CATRB, a stable clustering algorithm that uses the traffic regularity of buses while considering the mobility of vehicles such as velocity, position, and direction. In particular, we use the fixed routes of buses in urban areas as a reference index. In a regular triangle, its centroid, incenter, and circumcenter are all at the same point. Our scheme applies this idea to choose the most appropriate cluster header in VANETs. We develop an analytic model and a simulation model to evaluate the performance of CATRB. Simulation results show that the proposed scheme significantly improves cluster stability by decreasing the number of cluster head changes.

UAV-Assisted Supporting Services Connectivity in Urban VANETs

To keep the services and applications of intelligent transportation system stable and active, vehicular ad hoc networks (VANETs) are considered as an essential building block to maintain and manage its features. A wide deployment of VANETs is possible only after addressing numerous research challenges. One of the most complicated issues consists of designing a routing strategy, taking into consideration several serious constraints, and especially in a network such as VANET. The severity of these issues would be increased significantly when a VANET is deployed over an urban area, where we distinguish the high mobility of nodes and existing obstructions (e.g., buildings, bridges, tunnels, etc.). In this paper, an efficient routing solution based on a flooding technique is conceived to make the data delivery more reliable and to guarantee robust paths. Vehicles can cooperate in ad hoc fashion with existing unmanned aerial vehicles (UAVs). This kind of collaboration provides reliable routing paths and ensures alternative solutions in the case of path failures. Furthermore, a prediction technique is used to expect the expiration time of each discovered path. To limit the overhead over the network, all control packets are characterized by their static size making the originality of this work. Based on the simulation outputs, we discuss the performances of the proposed approach as compared with other dedicated previous schemes in terms of several metrics. The obtained results demonstrate that the hybrid communication between vehicles and UAVs based on the proposed flooding technique is perfectly suited to improve the data delivery process.