Broadcast Beacons Research Articles

CMAF: Context and Mobility-Aware Forwarding Model for V-NDN

Content dissemination in Vehicular Ad hoc Networks (VANET) is a challenging topic due to the high mobility of nodes, resulting in the difficulty of keeping routing tables updated. State-of-the-art proposals overcome this problem by avoiding the management of routing tables but resort to the so-called table of neighbors (NT) from which a next-hop is selected. However, NTs also require updating. For this purpose, some solutions resort to broadcasting beacons. We propose a Context- and Mobility-Aware Forwarding (CMAF) strategy that resorts to a Short-Term Mobility Prediction—STMP—algorithm, for keeping the NT updated. CMAF is based in Named Data Networking (NDN) and works in two modes, Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I). V2V CMAF leverages the overheard packets to extract mobility information used to manage NT and feed the STMP algorithm. V2I CMAF also uses a controlled and less frequent beaconing, initially from the Road-Side Units (RSUs), for a further refinement of the predictions from STMP. Results from extensive simulations show that CMAF presents superior performance when compared to the state of the art. In both modes, V2V and V2I (with one beacon broadcast every 10 s) present 5–10% higher Interest Satisfaction Ratio (ISR) than those of CCLF for the same overhead, at a cost of 1 s of increased Interest Satisfaction Delay (ISD). Moreover, the number of retransmissions of CMAF is also comparatively low for relatively the same number of hops. Compared to VNDN and Multicast, CMAF presents fewer retransmissions and 10% to 45% higher ISR with an increased overhead of about 20%.

Sybil Attacks Detection and Traceability Mechanism Based on Beacon Packets in Connected Automobile Vehicles.

Connected Automobile Vehicles (CAVs) enable cooperative driving and traffic management by sharing traffic information between them and other vehicles and infrastructures. However, malicious vehicles create Sybil vehicles by forging multiple identities and sharing false location information with CAVs, misleading their decisions and behaviors. The existing work on defending against Sybil attacks has almost exclusively focused on detecting Sybil vehicles, ignoring the traceability of malicious vehicles. As a result, they cannot fundamentally alleviate Sybil attacks. In this work, we focus on tracking the attack source of malicious vehicles by using a novel detection mechanism that relies on vehicle broadcast beacon packets. Firstly, the roadside units (RSUs) randomly instruct vehicles to perform customized key broadcasting and listening within communication range. This allows the vehicle to prove its physical presence by broadcasting. Then, RSU analyzes the beacon packets listened to by the vehicle and constructs a neighbor graph between the vehicles based on the customized particular fields in the beacon packets. Finally, the vehicle's credibility is determined by calculating the edge success probability of vehicles in the neighbor graph, ultimately achieving the detection of Sybil vehicles and tracing malicious vehicles. The experimental results demonstrate that our scheme achieves the real-time detection and tracking of Sybil vehicles, with precision and recall rates of 98.53% and 95.93%, respectively, solving the challenge of existing detection schemes failing to combat Sybil attacks from the root.

AFB-GPSR: Adaptive Beaconing Strategy Based on Fuzzy Logic Scheme for Geographical Routing in a Mobile Ad Hoc Network (MANET)

In mobile ad hoc networks (MANETs), geographical routing provides a robust and scalable solution for the randomly distributed and unrestricted movement of nodes. Each node broadcasts beacon packets periodically to exchange its position with neighboring nodes. However, reliable beacons can negatively affect routing performance in dynamic environments, particularly when there is a sudden and rapid change in the nodes’ mobility. Therefore, this paper suggests an improved Greedy Perimeter Stateless Routing Protocol, namely AFB-GPSR, to reduce routing overhead and increase network reliability by maintaining correct route selection. To this end, an adaptive beaconing strategy based on a fuzzy logic scheme (AFB) is utilized to choose more optimal routes for data forwarding. Instead of constant periodic beaconing, the AFB strategy can dynamically adjust beacon interval time with the variation of three network parameters: node speed, one-hop neighbors’ density, and link quality of nodes. The routing evaluation of the proposed protocol is carried out using OMNeT++ simulation experiments. The results show that the AFB strategy within the GPSR protocol can effectively reduce the routing overhead and improve the packet-delivery ratio, throughput, average end-to-end delay, and normalized routing load as compared to traditional routing protocols (AODV and GPSR with fixed beaconing). An enhancement of the packet-delivery ratio of up to 14% is achieved, and the routing cost is reduced by 35%. Moreover, the AFB-GPSR protocol exhibits good performance versus the state-of-the-art protocols in MANET.

AUV-Aided joint time synchronization and localization of underwater target with propagation speed uncertainties

The accurate sensor localization is one of the most basic requirements for the Underwater Acoustic Sensor Networks (UASNs) in many applications. However, in harsh underwater environment, the existence of propagation speed variation with depth (i.e., stratification effect) and asynchronous clock generally affects the ranging estimation, and in turn significantly decreases localization accuracy. Taking into account these specific characteristics of UASNs, we first propose an efficient Autonomous Underwater Vehicle (AUV) aided joint localization and time synchronization solution for UASNs, subjected to stratification effect constraint, in which AUV acts as a mobile anchor and broadcasts beacon signals periodically to provide localization reference for unknown target sensors. Next, since the estimation accuracy of localization and synchronization is very sensitive to the accuracy of the AUV locations, the joint localization and synchronization method in the case of inaccurate AVU locations is considered. Then, Cramer Rao Lower Bound (CRLB) analyses are presented for both accurate and inaccurate AVU locations cases. Finally, numerical simulation results show that the proposed method in this paper outperforms the existing ones in terms of estimation errors.

Performance Analysis and Optimization for Semi-Persistent Scheduling in C-V2X

For periodical beacon broadcasting in cellular vehicle-to-everything (C-V2X) networks, a distributed reservation media access control (MAC) protocol, the sensing-based semi-persistent scheduling (SPS), is adopted. However, how to quantify the communication reliability and latency is an open issue, which is critical for low-latency and high-reliability services. In this paper, an analytical model for SPS is presented, based on which the impacts of beacon rate, range settings and system configuration on access collision probability and delay outage probability are quantified. The analytical model provides important insights and guideline to adapt and optimize protocol parameters including the sensing range, transmit power and resource reservation. The enhanced MAC protocol can maintain high-reliability and low-latency services with a wide range of vehicle density. Simulations are conducted to validate the analysis and the results demonstrate that the proposed MAC enhancement solution can reduce collision probability while ensuring the delay outage probability based on service requirements.

BETA: Beacon-Based Traffic-Aware Routing in Vehicular Ad Hoc Networks

Data transmission in Vehicular Ad Hoc Networks (VANETs) often suffers from routing interruptions due to the unstable communication links between vehicles. Over the past decades, many traffic-aware routing protocols have been proposed to alleviate routing interruptions by sensing traffic conditions. However, in most traffic-aware routing protocols, vehicles must transmit a large number of control packets to accumulate traffic information, which may degrade network performance due to the resulting intense competition over the wireless medium. Instead of using control packets, we propose to leverage the beacon mechanism that has been widely used in VANETs to realize traffic awareness. Vehicles broadcast beacons to exchange necessary information with their neighbors periodically. We can leverage this information exchange process among vehicles to replace control packets. To realize this idea, first, a mathematical analysis is provided to demonstrate its feasibility. Then, we propose a concrete protocol to address the technical challenges of using beacons. Extensive simulation results show that our protocol performs better than the state-of-the-art counterparts regarding packet delivery ratio, average delivery time, and network overhead.

Optimal Joint Power and Rate Adaptation for Awareness and Congestion Control in Vehicular Networks

To support inter-vehicular applications, vehicles broadcast beacons with information about their state. Congestion may occur when the load on the channel due to beaconing can prevent the transmission of other types of messages. In this paper, we propose a distributed algorithm for optimal joint adaptation of transmit power and beaconing rate for congestion and awareness control. Our approach is based on a network utility formulation of the congestion control problem, which allows us to induce a desired fairness notion and set different priorities for vehicles. We formulate the general problem but, since it is not convex, we assume Rayleigh fading and derive an algorithm, called PRAIOS, that solves the optimization problem in a decentralized way with convergence guarantees. Our results, validated with realistic simulations in both static and dynamic scenarios and compared with other proposals, show that PRAIOS quickly converges to close to optimal allocations, while keeping the maximum beaconing load at the desired level. They also show that it can control the load when the fading is not Rayleigh. Applications can dynamically set their requirements as constraints, that are enforced by the algorithm while complying with the maximum load, which allows seamless integration of operational requirements into the control framework.

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.

A Distributed Mix-Context-Based Method for Location Privacy in Road Networks

Preserving location privacy is increasingly an essential concern in Vehicular Adhoc Networks (VANETs). Vehicles broadcast beacon messages in an open form that contains information including vehicle identity, speed, location, and other headings. An adversary may track the various locations visited by a vehicle using sensitive information transmitted in beacons such as vehicle identity and location. By matching the vehicle identity used in beacon messages at various locations, an adversary learns the location history of a vehicle. This compromises the privacy of the vehicle driver. In existing research work, pseudonyms are used in place of the actual vehicle identity in the beacons. Pseudonyms should be changed regularly to safeguard the location privacy of vehicles. However, applying simple change in pseudonyms does not always provide location privacy. Existing schemes based on mix zones operate efficiently in higher traffic environments but fail to provide privacy in lower vehicle traffic densities. In this paper, we take the problem of location privacy in diverse vehicle traffic densities. We propose a new Crowd-based Mix Context (CMC) privacy scheme that provides location privacy as well as identity protection in various vehicle traffic densities. The pseudonym changing process utilizes context information of road such as speed, direction and the number of neighbors in transmission range for the anonymisation of vehicles, adaptively updating pseudonyms based on the number of a vehicle neighbors in the vicinity. We conduct formal modeling and specification of the proposed scheme using High-Level Petri Nets (HPLN). Simulation results validate the effectiveness of CMC in terms of location anonymisation, the probability of vehicle traceability, computation time (cost) and effect on vehicular applications.

NC–MAC: A Distributed MAC Protocol for Reliable Beacon Broadcasting in V2X

Beacon broadcasting is of great importance in improving road safety and avoiding dangerous situations in vehicular ad hoc networks (VANETs). In order to support emerging vehicular applications such as autonomous driving, the reliability of beacon broadcasting becomes an indispensable issue which is also difficult given the highly dynamic topology and vehicle density. For the territories which are not covered with communication infrastructure, controlling and scheduling in a centralized way may not be applicable. Therefore, vehicle-to-vehicle (V2V) ad hoc communication is promising to address the ubiquitousness coverage concern. In this paper, a distributed network coding-based medium access control protocol (NC-MAC) is proposed to support V2V beacon broadcasting. We combine the preamble-based feedback mechanism, retransmissions, and network coding together to enhance broadcasting reliability. Extensive simulations are given to show the performance gain of NC-MAC protocol compared to the existing 5 G cellular vehicle-to-everything (C-V2X) MAC protocol in a wide range of scenarios including highway and urban vehicle traces generated by simulation of urban mobility (SUMO). The results show that the proposed protocol can improve the communication reliability as well as scalability.

Traffic Condition Aware Customized Beacon Broadcasting (TCA-CBB) Method for Efficient Broadcasting in VANET

Traffic Condition Aware Customized Beacon Broadcasting (TCA-CBB) Method for Efficient Broadcasting in VANET

MDPRP: A Q-Learning Approach for the Joint Control of Beaconing Rate and Transmission Power in VANETs

Vehicular ad-hoc communications rely on periodic broadcast beacons as the basis for most of their safety applications, allowing vehicles to be aware of their surroundings. However, an excessive beaconing load might compromise the proper operation of these crucial applications, especially regarding the exchange of emergency messages. Therefore, congestion control can play an important role. In this article, we propose joint beaconing rate and transmission power control based on policy evaluation. To this end, a Markov Decision Process (MDP) is modeled by making a set of reasonable simplifying assumptions which are resolved using Q-learning techniques. This MDP characterization, denoted as MDPRP (indicating Rate and Power), leverages the trade-off between beaconing rate and transmission power allocation. Moreover, MDPRP operates in a non-cooperative and distributed fashion, without requiring additional information from neighbors, which makes it suitable for use in infrastructureless (ad-hoc) networks. The results obtained reveal that MDPRP not only balances the channel load successfully but also provides positive outcomes in terms of packet delivery ratio. Finally, the robustness of the solution is shown since the algorithm works well even in those cases where none of the assumptions made to derive the MDP model apply.

BLESeis: Low-Cost IoT Sensor for Smart Earthquake Detection and Notification.

The Internet of Things (IoT) has been implemented to provide solutions for certain event detection because of ease of installation, computing and communication capability, and cost-effectiveness. Seismic event detection, however, is still a challenge due to a lack of high-fidelity sensing and classification efficiency. This study proposes BLESeis, an IoT sensor for smart earthquake detection. BLESeis comprises three main parts: (1) high-fidelity vibration sensing using a MEMS accelerometer and digital filtering; (2) an embedded earthquake detection algorithm; (3) BLE (Bluetooth low energy) beacon for earthquake notification. For high-fidelity vibration sensing, a triggering algorithm and embedded finite impulse response (FIR) low-pass filter are developed. The acquired vibration is then classified by the earthquake detection algorithm developed to identify the earthquake signal from other vibration sources using time and frequency domain analysis. Upon detection of an earthquake, the BLE beacon broadcasts using the proposed data packet for efficient notification and visualization. The performance of the proposed system is evaluated through numerical simulations and a set of experiments using shaking table tests. The experiments show the feasibility of the low-cost earthquake detection and notification system.

Distributed and Adaptive Reservation MAC Protocol for Beaconing in Vehicular Networks

In vehicular ad hoc networks (VANETs), beacon broadcasting plays a critical role in improving road safety and avoiding hazardous situations. How to ensure reliability and scalability of beacon broadcasting is a difficult and open problem, due to high mobility, dynamic network topology, hidden terminal, and varying density in both the time and location domains. In this paper, wireless resources are divided into basic resource units in the time and frequency domains, and a distributed and adaptive reservation based MAC protocol (DARP) is proposed to solve the above problem. For decentralized control in VANETs, each vehicle's channel access is coordinated with its neighbors to solve the hidden terminal problem. To ensure the reliability of beacon broadcasting, different kinds of preambles are applied in DARP to support distributed reservation, detect beacon collisions, and resolve collisions. Once a vehicle reserves a resource unit successfully, it will not release it until collision occurs due to topology change. The protocol performance in terms of access collision probability and access delay are analyzed. Based on the analysis, protocol parameters, including transmission power and time slots duration, can be adjusted to reduce collision probability and enhance reliability and scalability. Using NS-3 with vehicle traces generated by simulation of urban mobility (SUMO), simulation results show that the proposed DARP protocol can achieve the design goals of reliability and scalability, and it substantially outperforms the existing standard solutions.

Adaptive Link Parameter for V2X Communication in Predictable Channel

In the internet of vehicles (IoV), periodic beacon messages carry the function of traffic safety data interaction. However, when traffic density increases, these beacons will cause channel congestion. To solve the problem, an adaptive link parameters (ALP) assignment protocol based on predictable channel condition is proposed. The channel condition is estimated by traffic density, signal to interference plus noise ratio and channel busy ratio. According to the prediction of channel condition, beacon broadcast interval, power and modulation coding scheme are assigned. Congestion is avoided by controlling these link parameters. Performance of ALP is evaluated in the OMNET simulation platform. Results show that: 1. Packet delivery rate and latency are guaranteed in both congestion and idle channels. 2. Broadcast coverage and successfully received beacons number are improved in idle channel. 3. Channel utilization is high while avoiding channel congestion.

An optimized Algorithm for broadcast beacon frequency and transmission power in VANETs

Power control has been an important branch of the research field for VANETs. In order to meet the safety of vehicle driving, Vehicle-to-Vehicle(V2V) communication has become a research hotpot simultaneously. In the internet of vehicles, most of the messages generated by V2V communication are implemented by broadcasting. This paper proposed a joint optimization algorithm for power control and broadcast beacon frequency based on the LTE-V2V communication protocol. This algorithm applies deep reinforcement learning (DRL) and designs a reward function that can represent the communication effect of LTE-V2V. The experimental results show that the proposed algorithm can better configure the transmitting power and broadcast beacon frequency of the vehicle terminal, and obtain more reliable communication effects in the dynamic traffic flow environment.

Towards Rear-End Collision Avoidance: Adaptive Beaconing for Connected Vehicles

Connected vehicles have been considered as an effective solution to enhance driving safety as they can be well aware of nearby environments by exchanging safety beacons periodically. However, under dynamic traffic conditions, especially for dense-vehicle scenarios, the naive beaconing scheme where vehicles broadcast beacons at a fixed rate with a fixed transmission power can cause severe channel congestion and thus degrade the beaconing reliability. In this paper, by considering the kinematic status and beaconing rate together, we study the rear-end collision risk and define a danger coefficient ρ to capture the danger threat of each vehicle being in the rear-end collision. In specific, we propose a fully distributed adaptive beacon control scheme, called ABC, which makes each vehicle actively adopt a minimal but sufficient beaconing rate to avoid the rear-end collision in dense scenarios based on individually estimated ρ. With ABC, vehicles can broadcast at the maximum beaconing rate when the channel medium resource is enough and meanwhile keep identifying whether the channel is congested. Once a congestion event is detected, an NP-hard distributed beacon rate adaptation (DBRA) problem is solved with a greedy heuristic algorithm, in which a vehicle with a higher ρ is assigned with a higher beaconing rate while keeping the total required beaconing demand lower than the channel capacity. We prove the heuristic algorithm's close proximity to the optimal result and thoroughly analyze the communication overhead of ABC scheme. By using Simulation of Urban MObility (SUMO)-generated vehicular traces, we conduct extensive simulations to demonstrate the efficacy of our proposed ABC scheme. Simulation results show that vehicles can adapt beaconing rates according to the driving safety demand, and the beaconing reliability can be guaranteed even under high-dense vehicle scenarios.

Pseudonym change strategy based on the reputation of the neighbouring vehicles in VANETs

Pseudonym change schemes have been studied in VANETs to guarantee the property of untraceability of the vehicles. This paper proposes a new condition based on the assumption that if there are no malicious vehicles around when a synchronous change triggers, there is no risk of tracking, and the pseudonym change defers until a time threshold. Thus, our proposal based on a synchronous strategy to increase the anonymity set, adds to the change condition, the checking of the reputation status of the neighbouring vehicles. The reputation status is the result of discretizing the reputation score of the vehicles and it is part of the periodically broadcast beacon messages. The proposal was evaluated through simulations using a real scenario. The results showed an optimization in the use of pseudonyms maintaining similar anonymity levels with other schemes.

Speed Adaptive Beacon Broadcast for Information Dissemination in Vehicular Ad hoc Networks

Vehicular Ad hoc Network has been a key component of the Intelligent Transport System. An efficient mechanism for dissemination of information in VANETs is a challenging task. The high mobility of vehicular nodes and varying traffic flows makes selection of best relay vehicle to disseminate information a taxing task. Periodic beaconing for gathering information about the vehicles in the vicinity is though commonly employed in VANETs, but it degrades the performance resulting in channel contention and collisions. This paper presents a Speed Adaptive Beacon Broadcast approach that controls the beaconing rate depending upon the speed at which the vehicle is moving in comparison to the other vehicles in its locality. The selection of the relay vehicle is done keeping in consideration its distance from the source, local density and priority is given to the vehicle at an intersection. The approach is evaluated for both highway and urban scenario and simulation outcome reveals that SABB performs well in comparison to some of the existing approaches.

Diffusion-Based Reference Broadcast Synchronization for Molecular Communication in Nanonetworks

Molecular communication is a novel inter-disciplinary communication methodology at the nanoscale, which uses chemical or biological molecules as the information carriers. For many prospective molecular communication applications, the clock synchronization is a major issue. However, the existing solutions use the molecule releasing time for the clock synchronization schemes but ignore the molecule synthesizing time, which is not practical. To overcome this issue, in this paper, we propose a reference broadcast synchronization scheme. One nanomachine sends a broadcast beacon and the other two nanomachines records their receiving times. The receiving times are exchanged by that two nanomachines, then, the clocks between these two nanomachines can be synchronized. Owing to the fact that the information molecules propagate slowly with a large propagation delay, which also depends on the transmitter–receiver distance, so a delay estimation method is adopted in the synchronization scheme. The simulation results evaluate proposed synchronization scheme and show that the proposed scheme outperforms other clock synchronization schemes for molecular communication.