Multi-hop Broadcast Research Articles

Proposed Supercluster-Based UMBBFS Routing Protocol for Emergency Message Dissemination in Edge-RSU for 5G VANET

Vehicular ad hoc networks (VANETs) can bolster road safety through the proactive dissemination of emergency messages (EMs) among vehicles, effectively reducing the occurrence of traffic-related accidents. It is difficult to transmit EMs quickly and reliably due to the high-speed mobility of VANET and the attenuation of the wireless signal. However, poor network design and high vehicle mobility are the two most difficult problems that affect VANET’s network performance. The real-time traffic situation and network dependability will also be significantly impacted by route selection and message delivery. Many of the current works have undergone studies focused on forwarder selection and message transmission to address these problems. However, these earlier approaches, while effective in forwarder selection and routing, have overlooked the critical aspects of communication overhead and excessive energy consumption, resulting in transmission delays. To address the prevailing challenges, the proposed solutions use edge computing to process and analyze data locally from surrounding cars and infrastructure. EDGE-RSUs are positioned by the side of the road. In intelligent transportation systems, this lowers latency and enhances real-time decision-making by employing proficient forwarder selection techniques and optimizing the dissemination of EMs. In the context of 5G-enabled VANET, this paper introduces a novel routing protocol, namely, the supercluster-based urban multi-hop broadcast and best forwarder selection protocol (UMB-BFS). The improved twin delay deep deterministic policy gradient (IT3DPG) method is used to select the target region for emergency message distribution after route selection. Clustering is conducted using modified density peak clustering (MDPC). Improved firefly optimization (IFO) is used for optimal path selection. In this way, all emergency messages are quickly disseminated to multiple directions and also manage the traffic in VANET. Finally, we plotted graphs for the following metrics: throughput (3.9 kbps), end-to-end delay (70), coverage (90%), packet delivery ratio (98%), packet received (12.75 k), and transmission delay (57 ms). Our approach’s performance is examined using numerical analysis, demonstrating that it performs better than the current methodologies across all measures.

Emergency message broadcasting scheme based on V2V and V2I

As an important part of the advanced Intelligent Traffic System (ITS) in the Internet of Vehicles (IoV), Vehicle to everything (V2X) communication technology provides reliable end-to-end connection and efficient packet transmission. Currently, the main challenge is design and implementation of the multi-hop broadcast protocol. In particular, the network topology is constantly changing because of the high-speed vehicle and diversified road structure, which troubles the selection of forward nodes. Therefore, we propose an Emergency Message Broadcast Protocol (EMBP). In this method, we select the optimal relay node according to the directionality and mobility, channel fading, and link connectivity and apply a suboptimal relay node selection mechanism to guarantee the reliability of broadcast. Simulation results show that EMBP is more efficient and stable than part classical protocols. Due to the complex communication environment of urban roads, to better improve the reliability of emergency message transmission, a broadcasting scheme Roadside Unit (RSU) Emergency Message Broadcast Protocol (REMBP), based on Vehicle to Vehicle (V2V) and Vehicle to Road (V2R) hybrid transmission of emergency messages is proposed on the basis of EMBP. Compared with EMBP, REMBP has better performance in terms of delivery rate, number of forwarding hops, end-to-end delay, average number of collisions, number of packet redundancy, and number of retransmissions.

Analysis of IEEE 802.11p-Based Intra-Platoon Message Broadcast Delay in a Platoon of Vehicles

For platooning applications, vehicles in a platoon require timely and reliable delivery of road-safety information in order to maintain the stable operation of the platoon. Intra-platoon message broadcast delay (InPB-delay) is a critical metric that is used to measure the message delivery performance in a platoon of vehicles, where a V2V multi-hop broadcast mode is used for message delivery. In this paper, we study the modeling and analyses of the InPB-delay for a platoon of connected and automated vehicles (CAVs), which employs an IEEE 802.11p EDCA mechanism for channel access. A 2-D Markov chain model is first built to describe a backoff procedure of a platoon broadcasting node, which takes into account the four access categories of different priorities in the EDCA mechanism. Based on the Markov model, a theoretical performance model is further derived to investigate the impacts of major system parameters on the InPB-delay, taking into account the effects of both platoon vehicles and non-platoon vehicles. The derived performance model is validated through simulation results and the impacts of major system parameters are investigated through numerical results. The InPB-delay model can be used to provide reference values for system parameter settings in order to ensure the stable operation of a platoon.

Studying and improving the performance of ETSI ITS contention-based forwarding (CBF) in urban and highway scenarios: S-FoT+

This paper evaluates the performance of ETSI ITS Contention-Based Forwarding (CBF) and ETSI Simple GeoBroadcast forwarding while disseminating warning messages over a Geographical Area in highway and urban scenarios. Our experimental evaluation considers the complete ETSI ITS architecture including the Decentralized Congestion Control (DCC) mechanism. We propose an enhanced CBF mechanism, named S-FOT+, which combines several improvements to the ETSI CBF algorithm. S-FoT+ has a similar or better performance than the ETSI forwarding algorithms regarding both reliability and end-to-end delay while requiring much fewer transmissions. The improvements are equally effective and efficient in both urban and highway scenarios with large Destination Areas. Finally, we evaluate the trade-offs that stem from using multi-hop broadcast mechanisms in urban settings with smaller Destination Areas when compared to single-hop broadcast. Results show that multi-hop mechanisms significantly improve coverage at the cost of an increased number of transmissions.

A Fast, Reliable, Opportunistic Broadcast Scheme With Mitigation of Internal Interference in VANETs

In VANETs, it is important to support fast and reliable multi-hop broadcast for safety-related applications. The performance of multi-hop broadcast schemes is greatly affected by relay selection strategies. However, the relationship between the relay selection strategies and the expected broadcast performance has not been fully characterized yet. Furthermore, conventional broadcast schemes usually attempt to minimize the waiting time difference between adjacent relay candidates to reduce the waiting time overhead, which makes the relay selection process vulnerable to internal interference, occurring due to retransmissions from previous forwarders and transmissions from redundant relays. In this paper, we jointly take both of the relay selection and the internal interference mitigation into account and propose a fast, reliable, opportunistic multi-hop broadcast scheme, in which we utilize a novel metric called the expected broadcast speed in relay selection and propose a delayed retransmission mechanism to mitigate the adverse effect of retransmissions from previous forwarders and an expected redundancy probability based mechanism to mitigate the adverse effect of redundant relays. The performance evaluation results show that the proposed scheme yields the best broadcast performance among the four schemes in terms of the broadcast coverage ratio and the end-to-end delivery latency.

Efficient distributed broadcasting algorithms for cognitive radio networks-enabled smart agriculture

Smart agriculture has a broad prospect with the fast development of information technologies, such as Internet of Things, big data, edge computing and artificial intelligence. As more intelligent devices are deployed for agricultural scenarios, such as quality monitoring and information aggregation, the communication channels among these devices will be crowded and the performance can be greatly affected. Cognitive Radio Networks (CRNs) are promising in promoting better spectrum utilization, where unlicensed users can opportunistically use the vacant spectrum assigned to licensed users. On the basis of CRNs, many agricultural scenarios can be empowered with efficient communication capabilities. However, the broadcasting problem, which handles the information dissemination, has not been thoroughly studied in CRNs. Existing works are either centralized solutions performing broadcast on single/multiple channels, or distributed algorithms without performance guarantee for general networks. In this paper, we propose efficient distributed algorithms with short broadcast delay and high success ratio. The difficulties lie in the non-uniform channel availability, which entails broadcasting on multiple channels even for single-hop neighbors, and the distributed behaviors, where the users are only aware of the local information. Our contributions are threefold. First, we propose an efficient distributed rendezvous algorithm which spurs the neighbors to find the common channels in a short time. Second, we handle the single-hop broadcast by presenting two distributed algorithms and they guarantee a successful broadcast in O(Δ2loglogN) and Δ time slots respectively, where N is the number of channels and Δ is the maximum number of neighbors. Finally, we extend these algorithms to multi-hop broadcast and the broadcast delay is only up to D times the delay of single-hop, where D is the network diameter. We also conduct extensive simulations and the results corroborate our theoretical analyses.

An Hybrid Heuristic optimal relay selection strategy for energy efficient multi hop cooperative cellular communication

One of the major constraints for mobile relay networks is energy-efficient communication owing to the restricted battery power of user terminals. Among them, the production method is cooperative cellular networks that focus on enhancing the data rate, network reliability, and network system capacity and also improving the spectrum resources in the Fifth Generation (5 G) networks. Thus, recent research works investigate the selection of mobile relays in vehicular networks and also the relay selection in cooperative communication. Here, the mobile relay is selected by the base station (operator) for every mobile user for reducing the cost with improved data rates and reducing the total transmission power. The selection of relay is performed by considering the benefits or utilities offered to three players such as mobile relay, mobile user, and operator. Conventional relay node selection approaches face challenges regarding reduced network lifetime, delay, increased energy consumption, and collusion attacks. For next-generation wireless networks, both energy efficiency and capacity are vital. To cope with these problems, a new multi-objective derived energy efficient accurate selection of relay in multi-hop cooperative cellular communication in the vehicular network through a hybrid heuristic strategy is implemented. The conventional approaches are utilized for probability-based multi-hop broadcasting for low latency. On the other hand, the major demerits of cellular communication are developing an effective multi-hop communication strategy that generates hidden node problems, and also it decreases the speed of the vehicles and the lack of infrastructure in network topology. Thus, this paper aims to propose a hybrid optimization model to choose the lowest count of multi-hops among the source and destination for the cooperative cellular vehicular communication network. The major issue well thought-out here is accurately choosing the count of hops or relays for appropriate communication, which is carried out through the multi-objective function regarding link reliability, energy consumption, outage probability, mobility factor, and transmission delay of the system. The adoption of the new hybrid algorithm with the aid of the Best Fitness-derived Crow Tunicate Swarm Optimization (BF-CTSO) algorithm is designed as the major contribution for optimally selecting the multi-hops between source and destination in a cooperative cellular communication network. Numerical results show that the proposed energy-efficient cooperative communication system outperforms traditional methods.

A scalable time-division-based emergency messages broadcast scheme for connected and autonomous vehicles in urban environment

Connected and Autonomous Vehicles (CAVs) technology promises to revolutionize the transportation sector by solving many safety and traffic efficiency challenges while significantly enhancing passengers' and drivers' comfort. Most of these applications are built upon multi-hop broadcast of information among vehicles, leading to an increased contention and thus higher collision probability due to the limited bandwidth available for vehicular communications. In this paper, we propose a novel Time-Division-based Broadcast (TDB) scheme to mitigate interferences originating from hidden nodes (i.e., vehicles) to meet the stringent safety applications requirements. Then, we use this broadcast scheme as a basis for designing a new efficient and scalable protocol for emergency messages dissemination in urban vehicular networks (UV-TDB: an Urban, Vehicular and Time-Division-based Broadcast protocol). The simulation experiments show that UV-TDB significantly improves the performance of multi-hop broadcast and outperforms two state of the art protocols in terms of the achieved reduction in broadcast overhead (up to 77.9%), packet collisions ratio (up to 93.5%), interference rate (up to 43.5%) and increase in message reception rate (up to 337.7%). The results highlight also that UV-TDB adapts better to varying levels of vehicle density, making it more scalable.

Multihop broadcasting of emergency message dissemination in Vehicular Adhoc Networks

Vehicular Adhoc Network (VANET) is a distinct type of Mobile Adhoc Networks (MANET) that makes use of moving vehicles as nodes to create a mobile network. The vehicles that are in radio range of each other can communicate with one another. Timely message dissemination is extremely important for the delivery of critical information. Generally, data dissemination in VANET is broadcast oriented. Multihop broadcasting can be used to spread emergency messages. In this paper, the proposed work is compared with the existing approaches using NS2. The simulation results show the reduction on transmission delay and improved packet delivery ratio.

Analysis and Optimization of Multihop Broadcast Communication in the Internet of Vehicles Based on C-V2X Mode 4

Cellular Vehicle-to-Everything (C-V2X) Mode 4, developed by 3GPP, supports vehicle-to-vehicle communication without a cellular base station via LTE sidelink. The messages transmitted in the Internet of Vehicles (IoV) include periodic single-hop broadcast Beacon messages and multi-hop broadcast Emergency messages triggered by events. In this paper, we analyze the impact of multi-hop broadcast of Emergency messages in C-V2X Mode 4 on the performance of Beacon messages and propose collision probability models for Beacon messages and Emergency messages. The non-periodicity nature and lower broadcast latency requirement of the multi-hop Emergency messages may cause resource allocation conflicts in the resource selection process of C-V2X Mode 4, thus result in forwarding collision of Emergency messages and collision of subsequent Beacon messages. Therefore, we propose several multi-hop broadcast schemes for Emergency messages to reduce the collision probability by assigning independent resource grants for Emergency messages and adjusting the number of forwarding nodes. The performance of Beacon messages and Emergency messages of several different forwarding schemes proposed are simulated. The simulation results show that the proposed broadcasting schemes significantly improve the performance of Beacon messages and Emergency messages.

Distribution of multi-hop latency for probabilistic broadcasting protocols in grid-based Wireless Sensor Networks

This paper provides a theoretical model for the computation of the probability density function of multi-hop broadcast latency when using probabilistic broadcasting schemes in Wireless Sensor Networks (WSN). The probability density functions of multi-hop latency are derived by considering the per-hop random delays employed in protocols and the geometry of the position of nodes. The assumptions of the model allow computation of probability density functions that approximate simulation results in a variety of network scenarios and per-hop random delay configurations. The accuracy of the theoretical predictions increases in scenarios with moderate redundancy of broadcast packets.

Joint Optimization of Multi-Hop Broadcast Protocol and MAC Protocol in Vehicular Ad Hoc Networks.

Beacon messages and emergency messages in vehicular ad hoc networks (VANETs) require a lower delay and higher reliability. The optimal MAC protocol can effectively reduce data collision in VANETs communication, thus minimizing delay and improving reliability. In this paper, we propose a Q-learning MAC protocol based on detecting the number of two-hop neighbors. The number of two-hop neighbors in highway scenarios is calculated with very little overhead using the beacon messages and neighbor locations to reduce the impact of hidden nodes. Vehicle nodes are regarded as agents, using Q-learning and beacon messages to train the near-optimal contention window value of the MAC layer under different vehicle densities to reduce the collision probability of beacon messages. Furthermore, based on the contention window value after training, a multi-hop broadcast protocol combined with contention window adjustment for emergency messages in highway scenarios is proposed to reduce forwarding delay and improve forwarding reliability. We use the trained contention window value and the state information of neighboring vehicles to assign an appropriate forwarding waiting time to the forwarding node. Simulation experiments are conducted to evaluate the proposed MAC protocol and multi-hop broadcast protocol and compare them with other related protocols. The results show that our proposed protocols outperform the other related protocols on several different evaluation metrics.

Stochastic traffic flow modeling for multi-hop cooperative data dissemination in VANETs

Vehicular networks need to ensure their systems to perform efficient resource allocations to the customer’s need. Vehicular networks have issues like data dissemination, packet loss and delay. Vehicles in the transmission range of a few hundred meters receive the messages in a single-hop scenario. Multi-hop forwarding messages can disseminate from source node to destination node. Due to intense stochastic traffic flow modeling on highways, servers remain busy, leading to a tremendous increase in waiting time, service time, blocking probability, and system response time. The Markov model (M∕G∕m∕m) analyzes the mobility at intersections to provide a solution. The model reduces congestion control and maximizes the network performance in Vehicular Ad-hoc Networks (VANETs). With this optimized network flow control performance, we propose a Multi-hop Cooperative Data Dissemination (MHCDD) based on buffer control, which can be more efficient when applied with a Markov process. We formulate and analyze the delay in the multi-class queueing system, enhancing data traffic forwarding from V2V and RSU or BS. Performance analysis and simulation outcomes show the proposed MHCDD significantly improves the stochastic multi-hop broadcast model. The single-hop end-to-end delay, waiting time, response time, throughput, blocking probability, and packet loss probability are optimized. System modeling improves the queue length, delay, and packet loss of the broadcast scheme’s queue using the IEEE 802.11p system.

Intelligent Dynamic Spectrum Access Using Deep Reinforcement Learning for VANETs

In vehicular ad hoc networks (VANETs), vehicles can communicate with other vehicles or devices through vehicle-to-X communication. However, with the rise of the Internet of Things, it is a real challenge to make the limited spectrum resource meet the increasing communication demands, i.e., the channel contention problem. To solve this problem, this paper proposes a strategy combining multi-hop forwarding through vehicles and dynamic spectrum access. Firstly, a group-based multi-hop broadcast protocol, G-hop, is proposed. G-hop classifies vehicles with similar characteristics such as moving speed and communication distance into same groups using the depth-first-search algorithm. Messages are forwarded within a group in priority and then across groups, which limits both the range and the number of relay vehicles, i.e., channel contenders. Further, we adopt deep reinforcement learning techniques to achieve dynamic spectrum access. We design a Global Optimization algorithm based on Experience Accumulation (GOEA) using deep reinforcement learning. In GOEA, a network structure combined with recurrent neural network and deep Q-network is proposed for learning the time-varying process, and then a reward method is applied to optimize the global utility. Vehicles that need to transmit messages select channels dynamically following the guidance of GOEA. The experimental results demonstrate that the G-hop protocol reduces the packet loss rate from 0.8 to about 0.1. Meanwhile, compared with Slotted Aloha and DQN, our GOEA algorithm reduces the collision probability and channel idle probability by 60%. Moreover, as the number of vehicles increases, the transmission success rate can be improved by 20%.

Road network layout based multi-hop broadcast protocols for Urban Vehicular Ad-hoc Networks

In recent years, the decentralized wireless Vehicular Ad hoc Networks (VANETs) have emerged as a key technology for Intelligent Transportation Systems (ITS). The need for an efficient and reliable broadcast protocol, mainly in urban VANETs, is of great importance to support different services such as road safety, traffic efficiency, entertainment and advertisement. This paper proposes two new routing broadcast protocols: the Enhanced Counter-based broadcast protocol in Urban VANET (ECUV) and the Enhanced distance-based broadcast protocol in Urban VANET (EDUV). Both of them improve the distribution of data on urban VANETs. ECUV and EDUV use a road-network-topology-based approach to select a set of relay nodes with enhanced coverage capabilities during the data delivery in urban Vehicle to Vehicle (V2V) scenarios. They also improve the performance of the receiver-based protocols by alleviating the negative effect of their stochastic behavior. We study the behavior of these protocols with an analytical model, which shows that the enhanced versions reduce the transmission probability in high vehicle density to avoid the broadcast storm problem. Moreover, the obtained results proved that these proposed protocols increase the transmission probability in low vehicle density to satisfy the reachability requirement of data broadcasting. The network simulation results show clearly that ECUV and EDUV outperform other methods in terms of coverage capacity and efficiency.

A Probabilistic Broadcasting Scheme for Emergent Message Dissemination in Urban Internet of Vehicles

The Internet of Vehicles (IoV) has attracted increasing attentions for its potential of enhancing driving safety and traffic efficiency. The Multi-hop broadcast is one of the important techniques for time-sensitive data dissemination especially in emergent cases. As a result, how to wisely select the next-hop during Multi-hop routing plays an important role for performance improvement in IoV as well as dependent applications. Nevertheless, in view of the high mobility, frequent changing topology and complicated channel environment, a hazardous and thoughtless selection of the next-hop is easy to make, thus leading undesirable results. To deal with this issue, in this paper, a probabilistic broadcasting protocol for emergent message dissemination (BP-EMD) in Urban IoV is proposed. As the selection guidance for relaying node, the weighted probability is envisioned for each potential relay candidate, which is the combination of distance, link availability and packet reception ratio. After that, the node with the greatest weighted probability has been given the highest priority to relay the packet. In case that the selected relay node fails the forwarding, the other nodes available for relay will assist to disseminate the packet. In this way, the transmission reliability of the emergent messages is significantly guaranteed. Numerical results indicate that our BP-EMD can achieve higher broadcasting efficiency and less redundancy with less delivery latency, average transmission numbers and average End-to-End delay, as well as high packets delivery ratio and dissemination efficiency, compared with some classical multi-hop broadcasting protocols.

An Efficient Cooperative Transmission Based Opportunistic Broadcast Scheme in VANETs

In vehicular ad hoc networks (VANETs), quick and reliable multi-hop broadcasting is important for the dissemination of emergency warning messages. By scheduling multiple nodes to transmit messages concurrently and cooperatively, cooperative transmission based broadcast schemes may yield much better broadcast performance than conventional broadcast schemes. However, a cooperative transmission requires multiple relays to achieve strict synchronization on both time and frequency, which may induce high cost for a cooperative transmission process. In this paper, we analyze the cost and benefit of a cooperative transmission for data broadcasting in vehicular networks, and introduce a new metric called the single hop broadcast efficiency (SBE) to evaluate the overall broadcast performance. We propose an efficient, non-deterministic cooperation mechanism to reduce the cooperation cost. The mechanism maximizes the expected broadcast performance by selecting cooperators with the largest expected SBE value for a lead relay, and initiates cooperative broadcasting process when the expected SBE value is larger than that of a single-relay based broadcasting. Based on the non-deterministic mechanism, we propose an efficient, cooperative transmission based opportunistic broadcast (ECTOB) scheme which further utilizes rebroadcast to improve the reliability of the broadcast scheme. Simulation results show that the proposed scheme outperforms the conventional ones.

Towards Fast and Reliable Multihop Routing in VANETs

In Vehicular Ad-hoc Networks (VANETs), fast and reliable dissemination of safety messages is a key step toward improving the overall road safety. In a highly dynamic VANET environment, safety message dissemination in a multi-hop manner is a challenging and complex problem that has gained significant attention recently. Many protocols and schemes have been proposed to efficiently share safety messages among vehicles. However, most existing techniques do not perform well under real-world traffic conditions, or perform adequately only under very limited scenarios and traffic conditions. This research proposes a highly efficient and reliable multi-hop broadcasting protocol, Intelligent Forwarding Protocol (IFP), that exploits handshake-less communication, ACK Decoupling, and an efficient collision resolution mechanism. In this research, IFP has been extensively studied and evaluated to establish its robustness and superiority over existing schemes. A key contribution of this paper is to present an in-depth analysis and optimization of IFP using theoretical modeling, thorough simulations, and extensive real-world experimentation. With IFP, the message propagation delay is significantly reduced and packet delivery ratio is drastically improved.

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.

Smart Fuzzy Logic-Based Density and Distribution Adaptive Scheme for Efficient Data Dissemination in Vehicular Ad Hoc Networks

In vehicular Ad Hoc Networks (VANETs), smart data dissemination is crucial for efficient exchange of traffic and road information. Given the dynamic nature of VANET, the challenge is to design an adaptive multi-hop broadcast scheme that achieves high reachability while efficiently utilizing the bandwidth by reducing the number of redundant transmissions. In this paper, we propose a novel intelligent fuzzy logic based density and distribution adaptive broadcast protocol for VANETs. The proposed protocol estimates the spatial distribution of vehicles in the network employing the Nearest Neighbor Distance method, and uses it to adapt the transmission range to enhance reachability. To reduce packet collisions, the protocol intelligently adapts the contention window size to the network density and spatial distribution. Bloom filter technique is used to reduce the overhead resulting from the inclusion of the neighbor IDs in the header of the broadcast message, which is needed in identifying the set of potential rebroadcasting vehicles. Our simulation results confirmed the effectiveness of the proposed scheme in enhancing reachability while efficiently utilizing bandwidth.