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Reliability is one of the key requirements for inter-vehicle communication in order to improve safety in road traffic. This paper describes the difficulties of inter-vehicle communica- tion. We focus on an analysis of the state-of-the art MAC protocol draft IEEE P802.11p and its limitations in high load situations. For our analysis we consider a pa...
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... the different demands of signal strength, the transmission range of a vehicle can be divided into three ranges, depending on the distance to the transmitting vehi- cle. Figure 1 displays them: The communication range is the area where both receiver sensitivity threshold and SINR are met for the payload. Vehicles within this range of the trans- mitting vehicle are able to decode packets. ...
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Citations
... For instance, different alignments of the used antennas for the DSRC between X-Nodes can lead to different radiation patterns and varying message success rates [67]. In addition, the presence of other signal obstructing vehicles that come in between X-Nodes affect the measured message success rate [68,69]. ...
... Simulations build on simplified models for real-world scenarios and may not reflect the actual system behavior [86]. For example, VANET models for simulations simplify complex signal interferences and, thus, do not represent real-world conditions [69]. ...
Communication between vehicles and their environment (i.e., vehicle-to-everything or V2X communication) in vehicular ad hoc networks (VANETs) has become of particular importance for smart cities. However, economic challenges, such as the cost incurred by data sharing (e.g., due to power consumption), hinder the integration of data sharing in open systems into smart city applications, such as dynamic environmental zones. Moving from open data sharing to open data trading can address the economic challenges and incentivize vehicle drivers to share their data. In this context, integrating distributed ledger technology (DLT) into open systems for data trading is promising for reducing the transaction cost of payments in data trading, avoiding dependencies on third parties, and guaranteeing openness. However, because the integration of DLT conflicts with the short available communication time between fast moving objects in VANETs, it remains unclear how open data trading in VANETs using DLT should be designed to be viable. In this work, we present a system design for data trading in VANETs using DLT. We measure the required communication time for data trading between a vehicle and a roadside unit in a real scenario and estimate the associated cost. Our results show that the proposed system design is technically feasible and economically viable.
... They are fading, path loss, interference, and Doppler shift. Gener ally, a wire channel is more reliable than wireless channel because there are some problems with fading [41] and path loss [42] in the wireless channel. Because of fading in signal strength with varying distance between the sender and receiver, path loss will happen which results in degraded signal reception. ...
... Due to the mo bility of vehicles in VANET, path loss could happen more frequently. Moreover, the fading also changes more rapidly due to interference from changing environ ments, obstacles, and buildings along the roads [42] . ...
VANETs enable vehicles to carry computing and communication platforms, so vehicles can communicate and exchange with each other distinct kinds of information. In VANETs, vehicles represent mobility nodes that directly exchange information in order to reduce the probability of traffic accidents. Nevertheless, VANETs still face many challenges that require developers and researchers to improve it. Data routing in VANETs attracts great attention from researchers and it is placed as the first priority since data dissemination is the main task in VANETs.
However, routing the packets is a challenging task due to the fast-changing topology and high mobility of the nodes. Most of the existing routing protocols proposed in VANETs are designed to deliver packets with a low packet dropping rate and low delay, but none of those protocols can meet the requirements of whole traffic scenarios. For these reasons, we are motivated to research the improvement of the data routing in VANETs.
This research thesis presents a routing protocol called Heuristic Routing with Infrastructure Nodes (HRIN) for data dissemination in vehicular networks. The main goal of this work aims to increase the packet delivery ratio and reduce the end-to-end delay. To achieve these goals, we propose two heuristic functions for Road Segments Selection (RSS) and Intermediate Nodes Selection (INS). Further, we propose the deployment of the Road-side Unit (RSU) on each road junction. RSUs can further assist the vehicles in data dissemination. The RSS is the combination of two probability functions, shortest distance, and higher connectivity. On the other hand, the INS is based on four quantities, vehicle's speed difference, vehicle's moving direction, number of packets on the vehicle, and signal fading. The simulation results of our proposed protocol achieved reasonable results for packet delivery ratio and end-to-end delay compared to the existing protocols.
... where is the total number of packets and is the number of lost packets. To compute PL, we assume that (a) The number of packets resulting from 3 or more packets colliding at any instant t is negligible [41]; and (b) The number of packets that fail to be detected by the receiver's radio device is negligible [42]. Therefore, the number of lost packets detected by vehicle , during , is equal to the sum of the number of nondecodable messages, , from senders located in the interference range of and the number of collisions, , due to "real" collisions of packets emitted from two senders that are both in range of the receiver (i.e., = + 2 × ). ...
Vehicular safety applications based on DSRC/802.11p have strict reliability requirement (greater than 0.99). However, it is difficult to achieve high reliability in wireless medium as the transmission is vulnerable to various wave propagation issues. To the best of our knowledge, none of the existing emergency message dissemination schemes, in the literature, achieves a predefined reliability in lossy channel. In this paper, we propose a novel scheme, called Reliable Emergency Message Dissemination scheme (REMD), that achieves a predefined reliability for message dissemination while satisfying delay requirements, for various channel conditions. We aim to guarantee very high reliability (e.g., 99%) in each hop, with low control overhead while keeping low end-to-end latency for time critical applications. We employ zero-correlated unipolar orthogonal codes (UPOC) to combat hidden terminal problem. We exploit periodic beacons, to accurately estimate reception quality of 802.11p wireless link in each cell; then, we use this information to determine optimal number of broadcast repetitions in each hop. In addition, to ensure reliability in multi-hop, we utilize cooperative communication. Simulation results show that REMD outperforms existing well-known schemes in the literature.
... Due to the short temporal validity of beacons, the size of the minimum contention window used by the backoff algorithm in IEEE 802.11p is often kept small. However, reducing the size of the minimum contention window increases the probability of packet collisions in broadcast communications where no exponential backoff is considered [25]. The probability of packet collisions can be reduced by increasing the size of the minimum contention window; but, it has a negative effect on end-to-end latency. ...
... Improving cooperative awareness is not sufficient to guarantee the quality of service required by safety-critical applications. The main reason is that increasing the beacon rate also leads to more packet collisions, especially for high vehicular densities and low minimum contention windows [25], [35]. Further, CBR is generally used as a priority metric, and other critical performance metrics directly related to road safety, such as position error, packet collision rate, PDR, and end-to-end latency are not considered. ...
... The initial contention window size is limited by the minimum contention window. For broadcast communication, there is no error-handling (e.g., no acknowledgments) and hence no exponential backoff growth [25]. As the contention window size is not increased, the size of the minimum contention window always defines the upper limit for the backoff counter. ...
Cooperative vehicular safety systems are expected to revolutionize the driving experience by providing road safety applications based on incident detection. Two vital quality parameters for cooperative safety applications are the position accuracy and communication reliability of the status information. The receiver may take erroneous decisions if the received data does not correspond to the latest situation of the transmitter (e.g., position, velocity, and trajectory of the target vehicle). In this paper, we propose and evaluate a POSition-ACCuracy (POSACC) based adaptive beaconing algorithm for cooperative vehicular safety systems. POSACC integrates three different control mechanisms to guarantee specific performance metrics. It adopts the position accuracy and communication reliability as the highest priority metrics, due to their direct impact on the vehicle’s systems capability to avoid potential traffic accidents in real-time. In addition, it guarantees the priority metrics, maintaining the vehicle’s warning distance, channel load, and end-to-end latency into the operative range of cooperative safety applications. POSACC is compared with three different state-of-the-art adaptive beaconing algorithms; ETSI DMG, LIMERIC, and DC-BTR&P. Extensive evaluation results show that POSACC successfully controls the beacon rate, transmission power,
and the size of the minimum contention window. Simulation results also demonstrate that POSACC is more effective than the benchmark algorithms by guaranteeing the operational requirements of cooperative safety applications in a wider range of traffic situations.
... According to the specification of the IEEE 802.11 [6] related to receiver sensitivities, they range between -68 dBm ( ͳǤͷͺ ൈ ͳͲ ିଵ ) and -85 dBm ( ͵Ǥͳ ൈ ͳͲ ିଵଶ ) depending on the modulation type, which is a lot lower than the above obtained results which guarantees required connectivity among the nodes. ...
In this paper, a new Hybrid Vehicular Sensor Networks (HVSN) Media Access Control (MAC) protocol is designed to exchange safety and control messages with high delivery rates between the vehicles' on board sensors and the road side sensors. The proposed protocol uses Time Division Multiple Access (TDMA) which imposes few challenges in implementation, namely, rescheduling and time synchronization. The devised MAC protocol is characterized by three features; first, it is a collision-free MAC protocol that does not require the re-configuration of time slots division as well as it accounts for the time synchronization problem. Second, the protocol is one of the works that employs the IEEE 802.11p in HVSN and utilizes its features and specifications. Third, the design is comprehensive and it is built based on a realistic mobility model that helped in assessing the protocol performance through a unique TDMA mobility based-Packet Delivery Ratio (PDR) calculation method.
... The increasing data volume and vehicle density in urban area challenge the effectiveness of data dissemination in VANETs. As presented in [6], the data transmission throughput in a VANET (hereafter, referred to as data throughput 1 ), which is an important measurement of data dissemination performance [7], could be significantly decreased with increasing vehicle density and increasing data volume. Considering that the data requests submitted by a large population of vehicles compete for the limited resource of wireless spectrum for data transmission, an inevitable proportion of the resource is wasted on wireless interference (i.e. ...
... Any theoretical propagation model and empirical model can be directly applied to the proposed solutions to be introduced in Sect. 6. ...
... At the end of the simulation (i.e. the highest vehicle density), the data throughput of AODV and DSRV are almost zero, whereas the data throughput of DSR is also at a low level. The results confirm the conclusion of [6] that the performance of data transmission in VANETs might be seriously impaired by wireless interference. ...
Data dissemination in vehicular ad hoc networks (VANETs) has attracted researchers’ attention in recent years. However, due to high vehicle density in urban areas and increasing data volume, wireless interference seriously impairs data dissemination performance of a VANET. To alleviate the interference problem, we propose a cross-layer design to exploit both spatial and temporal reusability of wireless spectrum in VANETs. In particular, the proposed cross-layer design integrates power control in the physical layer, time division in the MAC layer and data routing in the network layer. To implement the cross-layer design, we formulate an interference-aware power-control (IAPC) problem with the objective of maximizing data throughput in a VANET. For solving the IAPC problem, an integer linear programming formulation is proposed to derive the optimal solution. In addition, an efficient heuristic algorithm, named IAPC-Solver, is proposed to achieve a near-optimal solution. Extensive simulation experiments have been conducted on a widely adopted testbed, and the experimental results illustrate that the cross-layer design together with the proposed algorithms are effective for improving data dissemination performance of a VANET.
... other nodes yet [12] identified vehicles' interference as a major reason for loss of packets. Increasing transmission power may not work well for mobile nodes in the presence of obstacles. ...
As a standard way of moving vehicles' communication, VANETs (Vehicular Networks) have been characterized with enormous ability to increase the effectiveness of traffic and enhance the safety of cars on roads. Connected vehicle technology aims at dealing with important road transportation issues that concern environment and safety. Vehicular network density varies depending on the traffic load which can be high in the city, or low in suburban areas. The research provided a realistic analysis of the DSRC performance for varying vehicle densities over physical areas for urban and highway traffic using data packet response times and throughput as parameters. The Packet Delivery Ratio, the ratio of successfully received packets to the total number of packets sent, helps examine the hidden terminal effect on the communication using multi-lane traffic simulations for highway and urban scenarios. Computer simulations were done for 20, 40, 80 and 150 communication nodes for each traffic scenario; urban and highway to observe the effect of varying vehicle densities on the vehicular network communication performance. DSRC performance was studied for the traffic while analyzing the changes in the control parameters. We then proposed a control algorithm that secured data packets to address transmission errors resulting from the possible hidden node problem by improving packet throughput and controlling transmission delay. The algorithm minimizes packet losses resulting from possible collisions by giving an improved number of processes completed per unit time (throughput) for an increasing packet rate and effectively controlling the delay. Traffic simulation was done using a combination of SUMO (Simulation of Urban Mobility), OMNeT++ and VEINS for varying vehicle densities. Index Terms-Collision avaoidance, DSRC, error control, packet delivery ratio, throughput, V2V, VANET--1 INTRODUCTION ehicular networks have attracted a lot of study interest in recent years. Road safety systems have been researched on and studies carried out to prevent road accidents or reduce the accident effects [1]. Vehicles and Road Side Units are communication nodes which have the ability to communicate and provide information in a bid to avoid traffic congestion that could lead to accidents. Dedicated Short Range Communications need to be as error free as possible in order to fulfil their safety-of-life objective. Vehicular networks use CSMA/CA, where transmission by communication nodes is done after sensing an idle channel [2]. Collision avoidance attempts channel division in almost equal proportions among the nodes transmitting in a communication range. In order for vehicles to share their broadcast information, they need to create an ad-hoc network, which requires a reliable low-latency vehicle-to-vehicle (V2V) communication that can handle firm rates. This requires fast and efficient V2V wireless communication, at 'data rates between 1 and 10 Mb/s' [3]. V2X's mobility of the wireless channels involved greatly affects the data packet throughput and response times. 'In US, 7.5 MHz spectrum [5.850-5.925 GHz] is allocated for DSRC', one of the key wireless technologies for Vehicular Networking. 'DSRC/WAVE operates in 5.9 GHz band (U.S) and 5.8GHz band (Japan, Europe) and has 75 MHz bandwidth allocated for vehicle communication, and range is up to 1 Km with vehicle speed of up to 140 Km/h' [4], [5]. Active safety applications need high levels of link reliability, in-teroperability, security and privacy. They require largely error-free performance. Vehicle-to-vehicle (V2V) communication that uses DSRC is estimated to be able to prevent up to 82% of car crashes in the United States, saving many lives and money [5].
... Despite the transmission standards, the major limitation of such shared wireless access is to maintain an accurate awareness about the local topology and safety situations on road through the exchange of beacons. Lack of awareness is caused by the channel congestion which increases under a high number of active vehicles [16], not to mention the strict requirements for high message frequency i.e., 10 Hz for most applications [17]. It follows that maintaining acceptable awareness and enhancing the performance of vehicular applications depends on the adaptive beaconing approaches. ...
The use of Information and Communication Technology (ICT) as a copilot for the drivers has a potential to improve traffic safety and efficiency. A key challenge in integrating ICT in vehicular networks is to provide the mechanisms for the delivery of safety messages called beacons. In particular, finding the trade-off between providing sufficient coverage and maintaining channel congestion remains the focus in the stipulated amendments for safety message transmissions. In this paper, we handle this trade-off by proposing a Multi-metric Power Control (MPC) approach, which uses application requirements and channel states to determine a transmit power for safety messages. The MPC gives a best-effort approach to satisfy the coverage range requirement of a message as specified by the application. Moreover, the concept distinguishes among message types to provide coverage differentiation. We show that the best-effort approach of providing coverage for different messages can control congestion and as a result improve awareness by minimizing beacon collisions. The performance analysis of MPC using discrete event simulation confirms its practicality.
... However, few studies of multipath video data transmission have focused on interference in the routing process. The studies in Wang, et al. [55] and Schmidt, et al. [56] are basically on using received signal strength as the estimating factor to measure interference level of a link, which is not adequate to have qualitative video streaming transmission due to dynamic nature of VANET nodes. Therefore, we use a geometric angle estimation, which can assist in minimizing interference in a multipath video streaming transmission. ...
The multipath transmission is one of the suitable transmission methods for high data rate oriented communication such as video streaming. Each video packets are split into smaller frames for parallel transmission via different paths. One path may interfere with another path due to these parallel transmissions. The multipath oriented interference is due to the route coupling which is one of the major challenges in vehicular traffic environments. The route coupling increases channel contention resulting in video packet collision. In this context, this paper proposes an Interference-aware Multipath Video Streaming (I-MVS) framework focusing on link and node disjoint optimal paths. Specifically, a multipath vehicular network model is derived. The model is utilized to develop interference-aware video streaming method considering angular driving statistics of vehicles. The quality of video streaming links is measured based on packet error rate considering non-circular transmission range oriented shadowing effects. Algorithms are developed as a complete operational I-MVS framework. The comparative performance evaluation attests the benefit of the proposed framework considering various video streaming related metrics. OAPA
... This hurts the effectiveness of time-critical safety applications for V2X. • Existing V2X research is either based on unrealistic simulation studies as in [15], [16], or on basic experimental deployments, where the security solutions are either evaluated independently from the other layers (e.g. Network, MAC, PHY, etc.) [17], or under limited operating conditions ( [18], [19]). ...
