车用自组网信息广播

车用自组网作为移动自组网在智能交通系统中的应用,有望为人们提供更安全、效率更高的旅行方式.广播协议为危险警告、协同驾驶、路况通报等交通信息的发布提供了有效途径.简要介绍了车用自组网的特点和应用分类.采用分析和比较方法,讨论各种信息广播协议的特点、性能差异和应用范围,并针对车用自组网的特点及应用需求指出未来信息广播模型的设计思想和突破方向.     

车用自组网信息广播

车用自组网作为移动自组网在智能交通系统中的应用,有望为人们提供更安全、效率更高的旅行方式.广播协议为危险警告、协同驾驶、路况通报等交通信息的发布提供了有效途径.简要介绍了车用自组网的特点和应用分类.采用分析和比较方法,讨论各种信息广播协议的特点、性能差异和应用范围,并针对车用自组网的特点及应用需求指出未来信息广播模型的设计思想和突破方向.     

Bee life-based multi constraints multicast routing optimization for vehicular ad hoc networks

A vehicular ad hoc network (VANET) is a subclass of mobile ad hoc networks, considered as one of the most important approach of intelligent transportation systems (ITS). It allows inter-vehicle communication in which their movement is restricted by a VANET mobility model and supported by some roadside base stations as fixed infrastructures. Multicasting provides different traffic information to a limited number of vehicle drivers by a parallel transmission. However, it represents a very important challenge in the application of vehicular ad hoc networks especially, in the case of the network scalability. In the applications of this sensitive field, it is very essential to transmit correct data anywhere and at any time. Consequently, the VANET routing protocols should be adapted appropriately and meet effectively the quality of service (QoS) requirements in an optimized multicast routing. In this paper, we propose a novel bee colony optimization algorithm called bees life algorithm (BLA) applied to solve the quality of service multicast routing problem (QoS-MRP) for vehicular ad hoc networks as NP-Complete problem with multiple constraints. It is considered as swarm-based algorithm which imitates closely the life of the colony. It follows the two important behaviors in the nature of bees which are the reproduction and the food foraging. BLA is applied to solve QoS-MRP with four objectives which are cost, delay, jitter, and bandwidth. It is also submitted to three constraints which are maximum allowed delay, maximum allowed jitter and minimum requested bandwidth. In order to evaluate the performance and the effectiveness of this realized proposal using C++ and integrated at the routing protocol level, a simulation study has been performed using the network simulator (NS2) based on a mobility model of VANET. The comparisons of the experimental results show that the proposed algorithm outperformed in an efficient way genetic algorithm (GA), bees algorithm (BA) and marriage in honey bees optimization (MBO) algorithm as state-of-the-art conventional metaheuristics applied to QoS-MRP problem with the same simulation parameters.     

F-Ant: an effective routing protocol for ant colony optimization based on fuzzy logic in vehicular ad hoc networks

Vehicular ad hoc networks (VANETs) are a subset of mobile ad hoc networks that provide communication services between nearby vehicles and also between vehicles and roadside infrastructure. These networks improve road safety and accident prevention and provide entertainment for passengers of vehicles. Due to the characteristics of VANET such as self-organization, dynamic nature and fast-moving vehicles, routing in this network is a considerable challenge. Swarm intelligence algorithms (nature-inspired) such as ant colony optimization (ACO) have been proposed for developing routing protocols in VANETs. In this paper, we propose an enhanced framework for ACO protocol based on fuzzy logic for VANETs. To indicate the effectiveness and performance of our proposed protocol, the network simulator NS-2 is used for simulation. The simulation results demonstrate that our proposed protocol achieves high data packet delivery ratio and low end-to-end delay compared to traditional routing algorithms such as ACO and ad hoc on-demand distance vector (AODV).

     

车载自组织网络中的数据分发机制

车载自组织网络（vehicular ad-hoc network,简称VANET）作为一种新型的移动自组织网络,应用前景广阔.鉴于长距离数据分发机制是支撑VANET应用的一个不可或缺的机制,提出了一种VANET下路边单元（roadsideunit,简称RSU）辅助的数据分发机制Ara,并在不同的交通场景下对其性能进行了评估.实验结果表明,即使在有RSU出现故障的情况下,Ara也可以保证较高的数据到达率、较小的延迟和较低的消息开销.同时,通过建立分析模型对Ara的数据传递延迟进行了理论分析.该分析模型建立在车辆的微观流模型之上,可以推导出不同RSU 部署场景下的数据传递延迟.模拟实验结果验证了模型的正确性,因此该分析模型可以对Ara数据传递的性能进行预测.     

FBSS:一种基于公平盲签名和秘密共享的车载网隐私保护方案*

车载自组织网络是移动自组网络及无线传感器网络在交通领域的一种应用,由车辆节点,路侧单元,服务提供商等构成的一种新型移动自组织网络。车载自组网络利用无线信道进行数据传输,由于车载自组织网络本身的开放性和传输信息的敏感性,不可避免的面临信息的泄漏和攻击。如何保证车载自组织网络中的身份隐私和可信通信是亟待解决的关键问题。现有的工作通常采用认证机制,但在车辆认证的过程中不可避免地泄漏了用户的隐私,随后提出的匿名认证方案解决了隐私保护问题却忽略了匿名滥用的情况。针对上述问题,本文提出一种基于公平盲签名和秘密共享的匿名认证方案-FBSS。通过安全性分析和实验,该方案具有较高的匿名性和较高的效率。     

移动边缘计算环境下基于改进GPSR的VANET路由算法

针对车辆自组织网络(VANET,vehicular ad-hoc network)中现有路由协议存在的路由选择错误、丢包率较高、服务质量低等问题,提出了移动边缘计算环境下,结合改进贪婪周边无状态路由(GPSR,greedy perimeter stateless routing)和自适应链路质量评估的VANET路由算法;首先,结合边缘计算构建了VANET通信模型,对其车辆位置和速度进行系统的理论分析;将边缘计算架构应用于VANET能够有效缓解计算量大、与车辆有限且不均的资源分布之间的矛盾;然后,提出了基于节点移动速度和节点间距离的改进GPSR协议,通过自适应链路稳定性和链路传递速率评估来选择合适的中继节点,动态更新链路;通过SUMO仿真平台对路由算法的性能进行评估,实验结果表明,相对于其他算法,所提算法受车辆密度、交通流以及车辆相对速度的影响较小,且提高了分组传送率(车辆数为300时传送率达到92%),减少端到端延迟(交通流为5时延迟降低到1.5 s),从而降低了通信开销。     

Securing one-way hash chain based incentive mechanism for vehicular ad hoc networks

One of the most promising applications of yet to come vehicular ad hoc networks (VANETs) is commercial advertising. However, in order to realize commercial advertising over VANET, proper incentives and security mechanisms must be taken into consideration due to the existence of selfish and/or malicious users in the real-world scenario. In this paper, we propose a secure incentive scheme for VANET advertising systems based on one-way hash chains. We also analyze the advertisement propagation behavior in our VANET advertising system using a mathematical model.     

RSU-based message authentication for vehicular ad-hoc networks

Message authentication that ensures a message is genuine and verifies the source of the sender is a key issue in vehicular ad hoc networks (VANETs). Because messages may provide life-critical traffic information or emergency messages transmitted by unfamiliar sources. Because the vehicle in a VANET transmits messages in real-time in a high-mobility environment, traditional PKI security schemes are not suitable for VANET. The use of roadside units (RSUs) makes message authentication in VANET easy, but it also causes two problems and needed to be solved: how to authenticate messages transmitted between two different RSU ranges, and how to hand off messages for the vehicles moving across different RSU communication ranges. This paper proposes a comprehensive message authentication scheme that enables the message authentication within intra and between inter RSU ranges and hand-off between different RSUs. The proposed scheme balances the overhead for computation and communication with security against attacks. Efficiency analysis and comparison with related works demonstrate that the proposed scheme is a superior message authentication method for VANET.     

The design of speedy seamless safe messaging mechanism in VANET

With the popularity of automobile, traffic safety and our lives are inseparable. In vehicular ad hoc networks (VANETs), the properties authenticity, privacy and traceability have already been considered in many previous researches. Many automotive systems combine their applications with smart life. In this paper, a speedy seamless safe (3-S) messaging mechanism for roadside-to-vehicle authentication and vehicle-to-vehicle communication is proposed. In addition to the essential requirements mentioned above, 3-S messaging mechanism is designed to reduce the computation cost and provide the seamless communication when the vehicle crosses the various regions. With better performance and availability, our scheme can be applied in various VANET applications, especially in safety systems to provide the drivers active safety.     

不同场景中VANET路由协议的仿真研究

仿真场景的构建对于车载自组网的性能具有很大的影响。在NS2网络仿真平台中添加了节点城区移动模型和存在障碍物时的无线信号传播模型,建立了VANET的网络模型,分别在三种不同场景中对DSR路由协议的性能进行了仿真分析。结果表明,在真实的仿真场景中VANET的性能有所恶化。达到了较为真实的仿真VANET的目的,得出的结论对VANET的仿真研究具有一定的参考价值。     

车载网中一种利用静态节点辅助的路由方法

车载自组织网络(Vehicular Ad Hoc Network,VANET)越来越引起人们的广泛关注,虽然该网络与传统的自组织网络有类似的地方,比如网络中的节点可以自组织和自管理。但是它有自己重要特征:网络中的节点具有很快的移动速度,由于这种高速的移动,造成车载网络拓扑结构频繁的变化,导致网络中多跳路由的频繁断开,进而对路由的可靠性和数据传输的质量带来很大的挑战。路由选择是实现VANET的关键。我们提出一种利用静态节点辅助的路由方法(Static-Node Assisted Routing,SNAR)来提高数据包的传输效率。模拟实验显示,SNAR在端到端延时等方面要优于其它的多跳路由方法。     

一种无线Ad Hoc网络的区分服务体系结构

提供服务质量保证是目前无线ad hoc网络的研究热点.本文对将区分服务应用于无线ad hoc网络进行了阐述,提出了一种应用于无线ad hoc网络的区分服务体系结构,最后进行了仿真验证.仿真结果证明,在无线ad hoc网络中区分服务可以在资源不够用的情况下,降低对低优先级的业务流的服务,保证对高优先级的业务流的服务,从而使得高优先级的业务流获得较大的吞吐量和较低的延迟.     

A Cross-Layer Approach to Multichannel MAC Protocol Design for Video Streaming Over Wireless Ad Hoc Networks

This paper presents a cross-layer design for a reliable video transmission over wireless ad hoc networks based on multichannel MAC protocol with TDMA. First, we conduct a study of the multichannel MAC protocol through Markov chain model. Based on this study, two novel cross-layer modules are adopted for the design of multichannel MAC protocol. First, we adopt maximum latency rate (MLR) as the channel quality metric. Unlike the traditional MAC design based on network allocation vector (NAV), MLR is implemented to provide differentiated traffic so that the channel with smaller MLR time is initiated for higher priority traffic. Second, we adopt two congestion-aware metrics, namely MAC utilization and queue length of MAC layer, to improve the congestion-aware routing protocols with AODV and DSR. These two novel modules allow the proposed MAC protocol design to achieve high performance video transmission over wireless ad hoc networks. Experimental results show that the proposed scheme outperforms the state-of-the-art schemes under multichannel environments in wireless ad hoc networks for as much as 3.6 dB in PSNR. Such significant performance enhancement confirms that the cross-layer approach is very effective for multichannel MAC protocol design.     

Offloading mobile data traffic for QoS-aware service provision in vehicular cyber-physical systems

Owing to the increasing number of vehicles in vehicular cyber-physical systems (VCPSs) and the growing popularity of various services or applications for vehicles, cellular networks are being severely overloaded. Offloading mobile data traffic through Wi-Fi or a vehicular ad hoc network (VANET) is a promising solution for partially solving this problem because it involves almost no monetary cost. We propose combination optimization to facilitate mobile data traffic offloading in emerging VCPSs to reduce the amount of mobile data traffic for the QoS-aware service provision. We investigate mobile data traffic offloading models for Wi-Fi and VANET. In particular, we model mobile data traffic offloading as a multi-objective optimization problem for the simultaneous minimization of mobile data traffic and QoS-aware service provision; we use mixed-integer programming to obtain the optimal solutions with the global QoS guarantee. Our simulation results confirm that our scheme can offload mobile data traffic by up to 84.3% while satisfying the global QoS guarantee by more than 70% for cellular networks in VCPSs.     

A hybrid channel assignment strategy to QoS support of video-streaming over multi-channel ad hoc networks

Currently multi-channel multi-interface ad hoc networks (multi-channel ad hoc networks) have received amount of interest, especially under the context of real-time traffics, such as video applications. Channel assignment is one of the key challenges in multi-channel ad hoc networks. In this paper, based on a representative hybrid channel assignment strategy named as HMCP, a statistic link load based hybrid channel assignment strategy, SLL-HCA, is presented to obtain a better channel assignment metric than that in HMCP. SLL-HCA is based on the HMCP protocol and adopts the statistic link load metric to ensure load balancing in a two-hop neighborhood, and to prevent both the hidden node problem and the exposed node problem. In addition, an enhanced strategy, VE-SLL-HCA, by setting harsher channel assignment conditions and reserving lower interference of routing path for video-streaming traffic than other non-video traffic, is proposed to improve the QoS support of video-streaming over multi-channel ad hoc networks. Simulation results show that SLL-HCA achieves better throughput performance than HMCP in the presence of background traffic including CBR traffic or VBR traffic; and, the PSNR QoS metric for video-streaming is enhanced when using VE-SLL-HCA compared with SLL-HCA and HMCP, which confirms the validity of the proposed strategy for video-streaming traffics. Moreover, the simulation results also indicate that non-video traffic unlikely suffers an unacceptable performance in terms of throughput.     

移动机会网络组播路由的研究进展

在移动机会网络中,节点进行机会式的连接通信,该方式被广泛应用于移动社交网络、车载智能网络、移动自组网络等场景中。移动机会网络群组通信在抢险救灾、社区消息分发及智能交通等领域具有极高的应用价值,组播路由技术是其关键技术之一。将移动机会网络组播路由分为传统组播路由和智能组播路由两类,重点介绍了智能组播路由的研究现状,并采用通用的性能指标对各组播路由策略进行了比较分析。分析结论为:智能组播路由由于考虑了移动机会网络的社会特性、节点缓存、能量及安全等特性,因此具有较好的综合性能。最后展望了组播路由在大数据缓存管理、群组安全策略、车载自组网及动态感知方面的研究前景。     

An energy-efficient geographic routing protocol design in vehicular ad-hoc network

The combination of vehicles and wireless communication has resulted in a promising future for vehicular ad hoc networks (VANETs). The VANET is a kind of network that can be built randomly, quickly and temporarily without any infrastructure. The routing of data in a VANET is a challenging task due to the high dynamics, unstable connection environments and transfer direction limit (real road planning) involved. However, it has been discussed that radio obstacles, as found in urban areas, have a significant negative impact on the performance of location based routing. Therefore, the design of a suitable routing protocol for VANETs is an important issue, especially in regard to inter-vehicle communication applications. This paper proposes a energy-efficient geographic routing algorithm that uses the direction, density and distance between nodes in the crossroad routing strategy, to improve the link stability. We compare the novel scheme, ad hoc on-demand distance vector, and dynamic source routing (DSR) for packet loss rate and average end-to-end delay in VANETs to reduce the power consumptions. The simulation results are obtained which demonstrate the power effectiveness of our proposed routing strategy.     

On-demand channel reservation scheme for common traffic in wireless mesh networks

Wireless mesh networks (WMNs) have recently gained momentum as a new broadband internet access technology to provide internet traffic. These networks have unique characteristics that make them different from ad hoc networks. These differences are as follows. First, WMNs are composed of static mesh routers that are equipped with multiple radio interfaces and turn each interface into a non-overlapping channel. These additional interfaces can create multiple concurrent links between adjacent nodes. Second, most of the traffic in WMNs is directed towards the gateway. Third, both local traffic and internet traffic are relayed by the mesh router to indeed destination. The Multi-Radio Ad hoc On-Demand Distance Vector (AODV-MR) developed to support multi-radio and does not take into account above-mentioned WMNs characteristics. In this paper, we propose an on-demand channel reservation scheme to reserve some of mesh router radio interfaces to support the gateway traffic while the remaining interfaces can be used to support the local traffic. Our scheme establishes high throughput paths for the traffic destined at the gateway, reduces the intra-flow and inter-flow interferences as well as to support full duplex node transmission.The scheme allows the gateway to assign a list of channels for each received gateway routing discovery message. Simulation results show that our proposed scheme significantly improves the performance of multi-radio multi-channel wireless mesh networks.