Beaconing Scheme Research Articles

A Traffic-Aware Beacon Scheme for Cooperative Driving and Network Routing Trade-Off

A Traffic-Aware Beacon Scheme for Cooperative Driving and Network Routing Trade-Off

Intelligent High-Awareness and Channel-Efficient Adaptive Beaconing Based on Density and Distribution for Vehicular Networks

In vehicle ad hoc networks (VANETs), a beacon is a periodic message sent to nearby vehicles containing essential details like the sender’s vehicle ID, location, speed, and direction. Maintaining the freshness of this information without causing network congestion requires adaptive beaconing to adjust to changes in mobility and network density. Our research, based on extensive simulation experiments, identifies specific parameter sets optimal for adapting beaconing rates to different scenarios. From this analysis, we introduce a novel scheme called high-awareness and channel-efficient adaptive beaconing (HACEAB), employing fuzzy logic to adapt to various environments and conditions. Initially, the protocol gauges network density using an adaptive threshold function, followed by estimating the node spatial distribution through the quadrat statistic method to discern uniform distribution or clustering. Utilizing these data, the protocol adjusts beaconing rates via appropriate input parameters for the fuzzy logic system. Remarkably, HACEAB represents the first beaconing scheme capable of simultaneously adjusting to changes in network density and spatial distribution. Furthermore, the protocol enhances performance by adapting transmission power to fluctuations in node density and distribution. NS-3 simulations validate the efficacy of these improvements.

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.

LDAB-GPSR: Location PreDiction with Adaptive Beaconing – Greedy Perimeter Stateless Routing Protocol for Mobile Ad Hoc Networks

In mobile ad-hoc networks (MANET), nodes are randomly distributed and move freely, and hence the network may face rapid and unexpected topological changes. In this paper, an improved greedy perimeter stateless routing protocol, called “LDAB-GPSR”, is proposed. LDAB-GPSR mainly focuses on maximizing the packet delivery ratio while minimizing the control overhead. In order to accomplish this, two techniques are introduced, the first one is the location prediction technique in which the greedy forwarding strategy is improved by choosing more stable routes for data forwarding. The second one is the adaptive beaconing technique in which the slow start algorithm is employed to adapt the beacon packet interval time based on the mobility of nodes and the data traffic load instead of using the periodic beaconing strategy. These two strategies together improve the overall performance of the GPSR routing protocol. The performance of the new proposed protocol is evaluated by carrying out several NS-2.35 simulation experiments. The simulation results show that LDAB-GPSR protocol outperforms the GPSR+Predict protocol in terms of packet delivery ratio, control traffic overhead, end to end delay, and throughput. The ratios of enhancement approaches 40%.

A Talk-Listen-Ack Beaconing Strategy for Neighbor Discovery Protocols in Wireless Sensor Networks.

Neighbor discovery is a fundamental function for sensor networking. Sensor nodes discover each other by sending and receiving beacons. Although many time-slotted neighbor discovery protocols (NDPs) have been proposed, the theoretical discovery latency is measured by the number of time slots rather than the unit of time. Generally, the actual discovery latency of a NDP is proportional to its theoretical discovery latency and slot length, and inversely proportional to the discovery probability. Therefore, it is desired to increase discovery probability while reducing slot length. This task, however, is challenging because the slot length and the discovery probability are two conflicting factors, and they mainly depend on the beaconing strategy used. In this paper, we propose a new beaconing strategy, called talk-listen-ack beaconing (TLA). We analyze the discovery probability of TLA by using a fine-grained slot model. Further, we also analyze the discovery probability of TLA that uses random backoff mechanism to avoid persistent collisions. Simulation and experimental results show that, compared with the 2-Beacon approach that has been widely used in time-slotted NDPs, TLA can achieve a high discovery probability even in a short time slot. TLA is a generic beaconing strategy that can be applied to different slotted NDPs to reduce their discovery latency.

Context-aware Hybrid Adaptive Beaconing for Driver Behavior Dissemination in VANETs

VANET is a special paradigm of high mobility ad hoc network that promotes communication among the vehicles to enhance traffic safety. Cooperative awareness is the basic principle of VANETs that is accomplished by periodic exchange of beacons/ WSMs between vehicles. Due to highly dynamic topology and irregular distribution of vehicles, there is a necessity of a flexible beaconing mechanism that maintains a balance between the required level of cooperative awareness and network load and overcomes the limitations of periodic beaconing scheme of IEEE 802.11p. We proposed a context-aware hybrid beaconing algorithm that piggybacks driver status in beacon and disseminates it to the neighboring vehicles to enhance safety. The complete context has been considered to get the value of driver status and initial network status using SBN. The proposed technique considers real-time network congestion status and dynamically adapts the transmission range and power parameters at PHY layer, and beacon interval and CW at MAC layer using EDCA mechanism. The performance of the proposed algorithm has been evaluated using SUMO and NS-3 based on PDR, WSM PDR, goodput, and EED. The proposed algorithm demonstrates comparable WSM PDR to the benchmark scheme of LIMERIC and outperforms periodic beaconing scheme by exhibiting 35% improvement in WSM PDR on CCH and 15% improvement in PDR on SCH. Further, our proposed approach depicts more realistic scenario by considering the complete context; and maintains balance between transmission of safety and non-safety messages, thus, preventing starvation of non-safety applications as compared to the techniques in the existing literature.

Older Adults Show Reduced Spatial Precision but Preserved Strategy-Use During Spatial Navigation Involving Body-Based Cues.

Older adults typically perform worse on spatial navigation tasks, although whether this is due to degradation of memory or an impairment in using specific strategies has yet to be determined. An issue with some past studies is that older adults are tested on desktop-based virtual reality: a technology many report lacking familiarity with. Even when controlling for familiarity, these paradigms reduce the information-rich, three-dimensional experience of navigating to a simple two-dimensional task that utilizes a mouse and keyboard (or joystick) as means for ambulation. Here, we utilize a wireless head-mounted display and free ambulation to create a fully immersive virtual Morris water maze in which we compare the navigation of older and younger adults. Older and younger adults learned the locations of hidden targets from same and different start points. Across different conditions tested, older adults remembered target locations less precisely compared to younger adults. Importantly, however, they performed comparably from the same viewpoint as a switched viewpoint, suggesting that they could generalize their memory for the location of a hidden target given a new point of view. When we implicitly moved one of the distal cues to determine whether older adults used an allocentric (multiple landmarks) or beaconing (single landmark) strategy to remember the hidden target, both older and younger adults showed comparable degrees of reliance on allocentric and beacon cues. These findings support the hypothesis that while older adults have less precise spatial memories, they maintain the ability to utilize various strategies when navigating.

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.

A Scheme for Delay-Sensitive Spatiotemporal Routing in SDN-Enabled Underwater Acoustic Sensor Networks

In underwater acoustic sensor networks (UASNs), the sensors are deployed at different areas of the ocean, which perform information collection and delay-sensitive routing to the data center for further processing or industrial computing. However, in UASNs, the network states have spatiotemporal characteristics due to tides or autonomous underwater vehicles. To steadily route the traffic especially when the spatiotemporal characteristics of the UASNs are considered, a network architecture with intelligent traffic engineering or routing policies is indispensable. In this paper, we employ software-defined networking (SDN) technology and propose an SDN-enabled distributed architecture for UASNs. Based on the proposed architecture, we propose a scheme DSR-SDN for delay-sensitive spatiotemporal routing in SDN-enabled UASNs. The DSR-SDN includes three phases: First, topology awareness; second, spatiotemporal characteristics estimation; and third, routing computation. Particularly, with SDN features, DSR-SDN provides topology awareness based on a proposed software-defined beaconing scheme. Based on the detected topology, the spatiotemporal characteristics of the network states are estimated based on a proposed SDN-based hierarchical node localizing approach SDN-HL. Lead by the SDN controllers, SDN-HL makes use of the proposed “minimum weighted gap” formulation and Adam algorithm to optimize the localization and builds the indirect links to increase the localization rate. To route the traffic through the network with spatiotemporal characteristics, we adopt the time-expanded network approach, based on which a spatiotemporal route decision can be made before the routing starts. The simulation results demonstrate that the proposed scheme, i.e., DSR-SDN, can conduct accurate spatiotemporal characteristic estimation for the network states and provide delay-sensitive spatiotemporal routing for the sensed data.

Characterizing Urban Vehicle-to-Vehicle Communications for Reliable Safety Applications

The IEEE 802.11p-based dedicated short range communication (DSRC) is essential to enhance driving safety and improve road efficiency by enabling rapid cooperative message exchanging. However, there is a lack of good understanding on the DSRC performance in urban environments for vehicle-to-vehicle (V2V) communications, which impedes its reliable and efficient application. In this paper, we first conduct intensive data analytics on V2V performance, based on a large amount of real-world DSRC communications trace collected in Shanghai city, and obtain several key insights as follows. First, among many context factors, the non-line-of-sight (NLoS) link condition is the major factor degrading V2V performance. Second, the durations of line-of-sight (LoS) and NLoS transmission conditions follow power law distributions, which indicate that the probability of experiencing long LoS/NLoS conditions both could be high. Third, the packet inter-reception (PIR) time distribution follows an exponential distribution in the LoS conditions but a power law in the NLoS conditions, which means that the consecutive packet reception failures rarely appear in the LoS conditions but can constantly appear in the NLoS conditions. Based on these findings, we propose a context-aware reliable beaconing scheme, called CoBe , to enhance the broadcast reliability for safety applications. The CoBe is a fully distributed scheme, in which a vehicle first detects the link condition with each of its neighbors by machine learning algorithms, then exchanges such link condition information with its neighbors, and finally selects the minimal number of helper vehicles to rebroadcast its beacons to those neighbors in bad link condition. To analyze and evaluate the CoBe performance, a two-state Markov chain is devised to model beaconing behaviors. The extensive trace-driven simulations are conducted to demonstrate the efficacy of CoBe .

Intelligent Context-Aware Communication Paradigm Design for IoVs Based on Data Analytics

IoVs have been envisioned to improve road safety and efficiency, and provide Internet access on the move, by providing a myriad of safety and infotainment applications to drivers and passengers. However, with limited spectrum resource, harsh wireless channel, and variable vehicle density, IoV communication faces severe challenges to achieve scalability, efficiency, and reliability. In this article, we propose a context-aware IoV paradigm design to enhance the communication performance, where the high-level contextual information is utilized to bring intelligence in the design. Specifically, through big data analytics on large-scale IoV communication traces collected from an extensive experiment conducted in Shanghai, we investigate the impacts of different contextual information on V2V communication performance. We reveal that among many types of contextual information, the NLoS link condition is a major one that significantly affects V2V link performance. Based on that observation, we discuss three critical but challenging communication paradigm designs with context awareness of V2V link conditions: smart medium resource allocation, efficient routing establishment, and reliable safety message broadcasting. Furthermore, we present a case study of a cooperative beaconing scheme, where machine learning methods are utilized to learn the real-time link contextual information, and vehicles in deep NLoS condition choose helpers to enhance the overall beaconing reliability.

Innovation and inter-organizational learning in the context of public service reform

This article examines links between innovation and inter-organizational learning in the context of public service reform. The theory-building and empirical research draws on longitudinal analysis using mixed methods and multiple stakeholder respondents, set in the context of the Beacon Scheme, an instrument of UK public service reform. The research examines two questions: first, how does inter-organizational learning contribute to innovation? Second, how do changes in the approach to inter-organizational learning shape changes in the approach to innovation over time? The research on the whole of English local government ( N = 388) used temporal bracketing to examine developments in three phases over nine years. The article builds theory about the inter-organizational learning underpinning innovation, and shows that the approach to innovation changed over time, shifting from learning to imitate, to learning to innovate. Points for practitioners • Innovation is underpinned by inter-organizational learning. • Organizations improved over time in their ability to acquire and use learning. • Innovation involves the sharing of tacit as well as explicit knowledge. • Over time, organizations learnt to shift from learning to imitate, to learning to innovate. • Improvement through inter-organizational learning was not uniform. Initially, differences between organizations widened as those able to acquire learning used it to improve more rapidly. • Adaptation to local context, not adoption of a single approach, is apparent but is underemphasized in public service reform. • Learning pull, not dissemination push, aids learning and improvement.

La-CTP: Loop-Aware Routing for Energy-Harvesting Wireless Sensor Networks.

In emerging energy-harvesting wireless sensor networks (EH-WSN), the sensor nodes can harvest environmental energy to drive their operation, releasing the user’s burden in terms of frequent battery replacement, and even enabling perpetual sensing systems. In EH-WSN applications, usually, the node in energy-harvesting or recharging state has to stop working until it completes the energy replenishment. However, such temporary departures of recharging nodes severely impact the packet routing, and one immediate result is the routing loop problem. Controlling loops in connectivity-intermittent EH-WSN in an efficient way is a big challenge in practice, and so far, users still lack of effective and practicable routing protocols with loop handling. Based on the Collection Tree Protocol (CTP) widely used in traditional wireless sensor networks, this paper proposes a loop-aware routing protocol for real-world EH-WSNs, called La-CTP, which involves a new parent updating metric and a proactive, adaptive beaconing scheme to effectively suppress the occurrence of loops and unlock unavoidable loops, respectively. We constructed a 100-node testbed to evaluate La-CTP, and the experimental results showed its efficacy and efficiency.

A Joint Control–Communication Design for Reliable Vehicle Platooning in Hybrid Traffic

Recent studies have shown that traffic safety and efficiency can be substantially improved by vehicle platooning , in which vehicles periodically broadcast their kinetic status to neighbors, known as beacon message dissemination . As a networked control system, vehicle platoon has attracted significant attention from both the control and networking areas. However, few studies consider the practical traffic scenario with both platoons and individual vehicles, and the proposed beaconing schemes lack the deep understanding of relationship between the beaconing performance and the requirements of the control mechanism. To address these challenging issues, we propose a joint control–communication design to achieve reliable vehicle platooning in a more realistic traffic scenario, wherein the traffic consists of both platoons and individual vehicles, and both periodic beacon messages and event-based safety messages shall be delivered together. Specifically, we first develop a comprehensive control-theoretical analysis to understand how the vehicular communication can affect features of platoon driving; based on the understanding, we then propose and analyze an adaptive platoon-based message dissemination scheme; finally, we conduct extensive numerical experiments to validate the effectiveness of the protocol and to confirm the accuracy of the our theoretical analysis.

Autonomous and adaptive beaconing strategy for multi‐interfaced wireless mobile nodes

AbstractAd hoc wireless communications rely on beaconing to manage and maintain several network operations and to share relevant network parameters among network nodes. Beacon frames are sent at the start of each beacon interval. The frequency of beaconing depends on whether beacon intervals are fixed size or may be adapted and regulated according to the perceived network and workload conditions. On the other hand, current mobile nodes usually embed several heterogeneous wireless interfaces that urge the design of an adaptive beaconing strategy. In this paper, we propose an autonomous and adaptive beaconing strategy for multi‐interfaced mobile wireless nodes that is capable of regulating the beacon interval size dynamically according to the perceived network conditions. The proposed strategy is based on a joint dynamic estimation of both the announcement traffic indication message (ATIM) window and the beyond‐ATIM window sizes for each beacon interval. Extensive simulations were conducted using OMNeT++ to ascertain the improvements achieved by autonomously regulating the entire beacon interval to take into account the network and workload conditions. Obtained results showed that the two proposed approaches improve significantly the efficiency of the network in terms of throughput, end‐to‐end delay, and power consumption. The proposed fixed beacon interval (fixed‐BI) approach stands as an enhanced version of the power‐saving multi‐channel MAC protocol (PSM‐MMAC). The proposed variable beacon interval (variable‐BI) approach, which regulates dynamically both of the ATIM and the beyond‐ATIM windows, outperforms both the fixed‐BI and the PSM‐MMAC. In particular, under nominal traffic loads, the end‐to‐end delay of the variable‐BI is much lower than those provided by the fixed‐BI and PSM‐MMAC. Copyright © 2015 John Wiley & Sons, Ltd.

Hybrid Adaptive Beaconing in Vehicular Ad Hoc Networks: A Survey

Beacon or safety messages are broadcasted in vehicular ad hoc networks (VANETs) to disseminate network state or emergency incident information to other vehicles in the network. The freshness of information depends upon the frequent transmission of beacons. Similarly, to increase the awareness area or communicating with the distant nodes, beacons are disseminated with a high transmission power. However, increasing the beacon transmission power or rate has a negative effect on information communication efficiency because of the finite bandwidth of the wireless link. Therefore, different schemes have been proposed to individually control beacon's transmission power, transmission rate, or contention window at the MAC layer, or any combination of those, to achieve quality beacon communication in VANETs. The latter case is called hybrid adaptive beaconing schemes. In literature, there are many hybrid adaptive beaconing schemes that control multiple communication parameters to efficiently broadcast beacon messages in VANETs. In this paper, we explicitly survey and summarized various aspects of those schemes. The open and challenging issues are also highlighted in this paper.

Dynamic packet beaconing for GPSR mobile ad hoc position-based routing protocol using fuzzy logic

Greedy perimeter stateless routing (GPSR) is a well-known position-based routing protocol in mobile ad hoc network (MANET). In GPSR, nodes use periodic beaconing (PB) strategy in broadcasting beacon packets to maintain up-to-date information on the geographical position of their neighbor nodes within their transmission boundary range. The nodes that receive beacon packets save all known neighbor nodes, along with their geographical position information, in their neighbor list to make effective routing decisions. Most recent studies on position-based routing protocols assume that the position information in the neighbor list of a node is accurate, although only a rough estimate of such position information is actually available to the node. Node mobility causes frequent network topology changes in MANETs. Thus, neighbor-to-neighbor relationships change frequently. Using the PB strategy leads to inaccurate node position information in the neighbor list of a node. In addition, it may cause the routing protocol to make suboptimal decisions and not route packets through the best-located neighbor within the transmission range of the node. This study presents an analysis of the influence of position information inaccuracy caused by network parameters such as beacon packet interval time (BPIT) and node moving speed (NMS) on the performance of GPSR position-based routing protocols. To overcome the effect of position information inaccuracy in the neighbor list of a node, we proposed a fuzzy logic dynamic beaconing (FLDB) strategy to improve the reliability of the neighbor list of a node by optimizing time between transmissions of beacon packets in position-based routing protocols. Optimization is based on the correlation between NMS, number of neighboring nodes (NoNNs) and BPIT using fuzzy logic control (FLC) mechanism. The simulation experiment shows the effectiveness of the FLC mechanism in improving overall performance of GPSR position-based routing protocol in terms of beacon packet control overhead, end-to-end delay, non-optimal hop, and false node position.

Enhancing the Performance of Geographical Routing Protocol in Highly Dynamic Mobility and Mobility Patterns

In geographical routing, each node takes the data forwarding decision based on the location information of its one-hop neighbors. Dissemination of location information is the key function of the geographic routing. The location error due to the node mobility models has direct impact on the geographical routing. Node mobility is a great challenge to the beacon based location broadcasting schemes. The general mechanism to optimize the local topology information according to the node mobility is Proactive beaconing schemes support specific mobility model, but it does not perform well under various mobility models. However, it is difficult to capture the changes in the network topology and fit the beaconing approach correctly to the various mobility models. This paper proposes the Context Aware Mobility Adaptive Location Update (CAALU) scheme which contains Distance and Traffic based Location update (DTL), Band Prediction (BP), and Conditional Location Update on Overhearing (CLUO). These schemes make CAALU more flexible to various mobility models. For supporting the mobility models, the DTL dynamically adjusts the beaconing interval based on the node distance and traffic. For simplification, it divides the node transmission area into inband and out-band region, and each node continuously exchange its location information with the out-band nodes. The BP mechanism predicts the mobile node region and broadcast the beacon only if the predicted distance error is greater than the threshold range. The CLUO mechanism employs the MAC layer overhearing concept whereby a node sends the beacon packet, when it overhears the data/beacon packet transmission from a new neighbor. Simulated results reveal the adaptability of CAALU on various mobility models.

차량 애드혹 네트워크에서 효과적인 상황 인지를 위한 이중 비콘 전송 기법

차량 애드혹 네트워크에서 비콘 전송은 가장 기본적인 메커니즘 중 하나이다. 차량 통신 시스템에서는 각 노드들의 비콘 교환을 통하여 주변 상황 인지를 비롯한 다양한 통신 서비스가 구현된다. 본 논문에서는 기존의 단일 비콘 전송 방식에서 벗어난 이중 비콘 전송 방식을 제안한다. 이중 비콘 전송 방식은 일반적으로 통신 시스템에서 고려되는 비콘을 차량 통신 시스템에 특화시켜 안전 서비스를 위한 비콘과 편의 서비스를 위한 비콘 두 가지 기능으로 나누어 각 기능에 따라 통신 파라미터를 분산시켜 적용하는 방식이다. 이러한 비콘 메커니즘의 성능을 평가하기 위하여 가장 대표적인 성능 지표인 거리에 따른 비콘 패킷 수신율을 실험, 제안하는 이중 비콘 전송 방식의 우수함을 검증하였다. 결론적으로 이중 비콘 전송 방식은 단일 비콘 전송 방식에 비하여 채널에 부하를 줄임과 동시에 더욱 넓은 통신 반경과 원활한 상황 인지 서비스를 가능하게 한다. 덧붙여, 제안하는 이중 비콘 전송 방식은 실제로 구현함에 있어서 복잡성이 적고, 다른 적응형 비콘 전송 방식을 함께 적용 가능하기 때문에 효용성이 뛰어나다. Beacon transmission is one of the fundamental mechanisms in vehicular ad hoc networks. Variety services including context awareness can be embodied by exchanging beacons in each vehicle. In this paper, we propose dual beacon transmission instead of traditional single beacon transmission for beaconing mechanism. dual beacon transmission divides beacon into two functions and operates two beaconing process independently. We verified the superiority of dual beacon transmission by comparing beacon packet delivery ratio with single beacon transmission. In conclusion, dual beacon transmission can reduce channel load and have both wider communication range and effective context awareness. In addition, implementing dual beacon transmission has less complexity and appliable with conventional adaptive beaconing schemes.

Beaconing as a service: a novel service-oriented beaconing strategy for vehicular ad hoc networks

Vehicular ad hoc networks are designed to increase traffic safety by enabling fast reactions of drivers in critical situations. Vehicles exchange beacon messages about their current state and position using wireless communication to establish a certain level of awareness. Based on the received information, the collision probability with neighboring vehicles can be calculated. To calculate a collision probability accurately, highly up-to-date knowledge about the movement of potential collision partners is required. Due to the dynamic network topology, vehicles are supposed to send periodic beacons at an increased transmit rate. However, as wireless communication suffers from packet interference issues in saturated communication channels, an increased beacon rate also raises the interference probability. Thus, decreasing interference by increasing the awareness level seems contradictory. To overcome this issue, we introduce our beaconing as a service (BaaS) approach, which follows two core aspects: first, controlling the beacon rate intelligently with respect to the real benefit of a message transmission (e.g., when a vehicle detects a potential collision situation); and second, utilizing the overall communication bandwidth, which is divided into several communication channels. In this sense BaaS specifies a context-aware request/response beaconing strategy utilizing multiple channels simultaneously.