一种网关辅助的渐进式分簇路由算法

提出了一种网关辅助的渐进式分簇路由算法。该算法在渐进式的分簇路由协议(AODV-clustering)的基础上,结合GORP协议,通过增加网关的功能,使网关在路由的发现和维护以及数据传送中分担簇首的部分工作,从而降低簇首节点成为网络瓶颈的可能性。仿真结果表明,该算法既保持了AODV-clustering的优点,且进一步缩短了路由建立的时间,提高了数据报文发送成功率。     

车联网中基于分布式博弈的移动网关选取算法

提出一种基于VANET-CELLULAR混合架构的车联网(VANET)。在这种架构下,车辆可以根据一些原则动态成簇,在这些簇中,通过车辆间分布式博弈快速选取最少数量的车辆作为移动网关,将本地VANET接入蜂窝网络,并随着簇的网络拓扑变化动态更新网关,以最大化车辆数据传输的性能。考虑到车辆节点的自私特点,分布式博弈可以有效地提高移动网关节点的积极性,使得算法的可行性增强。仿真结果表明该算法能高效选取车联网移动网关。     

无线传感器网络动态分簇路由BWAS的算法研究

为加快无线传感器网络(WSN)路径搜索速度,减少了路径寻优能量消耗,提出了基于最优-最差蚂蚁系统(BWAS)算法的无线传感器网络动态分簇路由算法。该算法是基于WSN动态分簇能量管理模式,在簇头节点间运用BWAS算法搜寻从簇头节点到汇聚节点的多跳最优路径,以多跳接力方式将数据发送至汇聚节点。BWAS算法在路径搜寻过程中评价出最优-最差蚂蚁,引入奖惩机制,加强搜寻过程的指导性。结合动态分簇能量管理,避免网络连续过度使用某个节点,均衡了网络节点能量消耗。通过与基于蚁群算法(ACS)路由算法仿真比较,本算法减缓了网络节点的能量消耗,延长了网络寿命,在相同时间里具有较少的死亡节点,具有较强的鲁棒性。     

基于BWAS的无线传感器网络静态分簇路由算法

为提高路径搜索效率,避免动态分簇较多的能量消耗,提出了基于最优-最差蚂蚁系统(BWAS)的无线传感器网络静态分簇路由算法.BWAS是对蚁群算法的改进,在路径搜寻过程中评价出最优最差蚂蚁,引入奖惩机制,加快了路径搜索速度.通过无线传感器网络静态分簇、簇内动态选举簇头,在簇头节点间运用BWAS算法搜寻从簇头节点到汇聚节点的多跳最优路径,能减少路径寻优能量消耗,实现均衡能量管理,延长网络寿命,且具有较强的鲁棒性.通过与基于BWAS的动态分簇和基于蚁群算法的动态分簇路由的仿真实验相比较,证实了本算法的有效性.     

基于Multi-Agent的多权值优化分簇算法及仿真研究

提出了一种基于Multi-Agent的多权值优化分簇算法,算法定义了多种Agent类型,在簇头选举阶段选取了影响簇头合理分布的多个网络参数,在簇的更新阶段采用移动Agent启发机制进行簇的局部更新.仿真结果表明,算法不仅可以选出合理的簇头,使能量均匀的消耗,还可以节省整个网络的能量消耗.     

基于博弈的大规模无线传感器网络分簇算法

合理的分簇方式能够有效延长大规模无线传感器网络(LS-WSN)的寿命,从而降低其部署使用成本。当前很多WSN分簇的研究均假设节点均匀分布,这与实际应用中的大规模WSN有所差距。该文针对节点非均匀分布的大规模WSN,提出了一种分簇算法。该算法在基于蜂窝结构虚拟网格的位置分簇之后,引入博弈理论设计分簇调整流程,使网络达到各簇中节点数尽量均匀的分簇状态。理论分析和仿真结果证明,通过该方法进行分簇,可以有效均衡各个簇中的节点数,从而延长网络有效寿命。     

一种基于网络密度分簇的移动信标辅助定位方法

现有移动信标辅助定位算法未充分利用网络节点分布信息,存在移动路径过长及信标利用率较低等问题。该文把网络节点分簇、增量定位与移动信标辅助相结合,提出了一种基于网络密度分簇的移动信标辅助定位算法(MBL(ndc))。该算法选择核心密度较大的节点作簇头,采用基于密度可达性的分簇机制把整个网络划分为多个簇内密度相等的簇,并联合使用基于遗传算法的簇头全局路径规划和基于正六边形的簇内局部路径规划方法,得到信标的优化移动路径。当簇头及附近节点完成定位后,升级为信标,采用增量定位方式参与网络其它节点的定位。仿真结果表明,该算法定位精度与基于HILBERT路径的移动信标辅助定位算法相当,而路径长度不到后者的50％。     

基于多层分簇优化的认知无线电网络协作频谱感知策略

针对认知无线电网络(CRN)中基于簇的频谱感知策略的检测性能和能耗问题,提出一种基于多层分簇优化的协作频谱感知策略。首先,将CRN分成多个簇,进而将簇分成多个组,再将组分成多个子组,构建三层分簇结构;然后,利用提出的优化算法获得最优的分簇参数和决策阈值;最后,通过投票机制和K-out-of-N规则对各级决策进行聚合,进行频谱感知。实验结果表明,该方案在获得较高主要用户(PU)频谱占用检测率的同时,能够最大限度地减少信道开销,提高了网络的吞吐量。     

无线传感器网络簇间节能路由算法

针对基于分簇网络的无线传感器网络簇间路由协议,让簇首和Sink节点直接通信或通过簇首节点转发数据造成能耗不均,节点过早死亡的缺陷。文中提出一种基于网关节点模型的无线传感器网络簇间路由算法,通过簇头与网关节点、网关节点自身建立虚电路,制定存储转发路由,将数据转发给Sink节点。并引入延时等待机制,增强了簇间信息的融合度,此算法适用于大规模无线传感器网络,有良好的可扩展性。仿真表明在能量节省等性能上与传统簇间路由算法相较有较大提高。     

基于区域的车载自组织网络节点分簇算法研究

针对车载自组织网络复杂的应用场景,提出了一种基于区域的网络分簇算法(ZACA)。将道路环境划分为路段区域(Segment)和路口区域(Intersection)分别计算节点的链路连通时间和连接度,并结合区域位置和传统综合权重的WCA分簇算法,实现不同道路模型下簇头的推举和分簇维护。仿真证明该算法能够有效地适应车载网络环境,能提高簇的稳定性、减少分簇开销,具有更高的稳定性。     

Domain load balancing routing for multi-gateway wireless mesh networks

As Wireless Mesh Networks (WMNs) are typically used for Internet access, most traffic is routed through the gateways which connect WMN to the wired network. As a result, the gateways tend to get congested and balancing of the traffic load of gateways is critical. In this paper, we consider applications that require continuous provision of a certain bandwidth to a server located at the wired network. If a path that satisfies the bandwidth request cannot be found, the request will be rejected, so that load imbalance will result underutilization of the network capacity. We present a novel load balancing routing algorithm for maximizing the network utilization (i.e., accommodating service requests as many as possible) for multi-gateway WMNs. In the proposed scheme, a WMN is divided into domains. Each domain is served by one gateway, so that all traffic of a domain is served by the corresponding gateway. Our scheme determines routing to balance the traffic load among domains, and then performs load balancing routing within each domain. Simulation results show that in square grid topologies, our intra-domain routing achieves near optimal performance with about 70% less overhead than the existing schemes. Our inter-domain load balancing scheme outperforms the existing heuristics by up to 25% while achieving about 80% performance of the optimal solution.     

Throughput Gateways-Congestion Trade-Off in Designing Multi-Radio Wireless Networks

In Wireless Mesh Networks (WMNs), traffic is mainly routed by WMN Backbone (WMNB) between the mesh clients and the Internet and goes through mesh gateways. Since almost all traffic has to pass through one of the MGs, the network may be unexpectedly congested at one or more of them, even if every mesh router provides enough throughput capacity. In this paper, we address the problem of congestion of gateways while designing WMNs. We propose a simultaneous optimization of three competing objectives, namely network deployment cost, interference between network channels and congestion of gateways while guaranteeing full coverage for mesh clients. We tailor a nature inspired meta-heuristic algorithm to solve the model whereby, several trade-off solutions are provided to the network planner to choose from. A comparative experimental study with different key parameter settings is conducted to evaluate the performance of the model.     

A Novel Gateway Selection Technique for Throughput Optimization in Configurable Wireless Mesh Networks

Wireless mesh networks (WMNs) have attracted much attention due to their low up-front cost, easy network deployment, stable topology, robustness, reliable coverage, and so forth. These advantages are suitable for the disaster recovery applications in disaster areas, where WMNs can be advantageously utilized to restore network collapse after the disaster. In this paper, based on a new network infrastructure for WMNs, to guarantee high network performance, we focus on the issue of throughput optimization to improve the performance for WMNs. Owing to selecting different mesh router (MR) as the gateway will lead to different network throughput capacity, we propose a novel gateway selection technique to rapidly select the optimal MR as the gateway, in order to maximize the network throughput. In addition, we take into account the traffic distribution for the MR to eliminate traffic congestion in our method. The performance of our proposed method is evaluated by both numerical and simulated analysis. The simulation results demonstrate that the gateway selection method is effective and efficient to optimize the throughput for WMNs.     

Enabling autonomicity in wireless mesh networks with the ETSI AFI GANA reference model

The distributed nature of wireless mesh networks (WMNs) allows them to benefit from multiple autonomic functionalities. However, the existing landscape of self‐x solutions (eg, self‐configuration) is fragmented and the lack of a standardized framework through which interoperable autonomics can be developed has been hampering adoption and deployment of autonomics in real‐world service networks. There is a need for a standardized architectural framework that enables to comprehensively support and integrate interoperable components for autonomicity in WMNs. Such an architecture (autonomicity‐enabled wireless mesh architecture) is currently being standardized by the working group called Evolution of Management towards Autonomic Future Internet (AFI) in the European Telecommunications Standards Institute within the Network Technologies Technical Committee. The proposed autonomic wireless mesh architecture is an instantiation of the AFI GANA (Generic Autonomic Network Architecture) reference model, a standards‐based approach to autonomics. This paper complements and extends the early version of the architecture by further detailing the architectural principles and providing experimental and validation results. First, we provide a brief overview of the AFI GANA reference model and then show how each of its building blocks can be instantiated for WMNs. We evaluate the proposed architecture by implementing and testing the 4 basic self‐x functionalities defined by the GANA model. The provided guidelines can now help researchers and engineers build autonomicity‐enabled WMNs using a standardized framework that enables adoption and deployment of autonomics by industry, thereby enabling researchers and engineers to contribute to the further evolution of the standard in the European Telecommunications Standards Institute.     

Design and implementation of multicasting for multi-channel multi-interface wireless mesh networks

Multicasting is a useful communication method in wireless mesh networks (WMNs). Many applications in WMNs require efficient and reliable multicast communications, i.e., high delivery ratio with low overhead among a group of recipients. In spite of its significance, little work has been done on providing such multicast service in multi-channel WMNs. Traditional multicast protocols for wireless and multi-hop networks tend to assume that all nodes, each of which is equipped with a single interface, collaborate on the same channel. This single-channel assumption is not always true, as WMNs often provide nodes with multiple interfaces to enhance performance. In multi-channel and multi-interface (MCMI) WMNs, the same multicast data must be sent multiple times by a sender node if its neighboring nodes operate on different channels. In this paper, we try to tackle the challenging issue of how to design a multicast protocol more suitable for MCMI WMNs. Our multicast protocol builds multicast paths while inviting multicast members, and tries to allocate the same channel to neighboring members in a bottom-up manner. By unifying fixed channels of one-hop multicast neighbors, the proposed algorithm can improve the performance such as reducing multicast data transmission overhead and delay, while managing a successful delivery ratio. In order to prove such expectation on the performance, we have implemented and evaluated the proposed solution on the real testbed having the maximum 24 nodes, each of which is equipped with two IEEE 802.11a Atheros WLAN cards.     

Responsive on-line gateway load-balancing for wireless mesh networks

We propose an adaptive online load-balancing protocol for multi-gateway Wireless Mesh Networks (WMNs) which, based on the current network conditions, balances load between gateways. Traffic is balanced at the TCP flow level and, as a result, the aggregate throughput, average flow throughput and fairness of flows improves. The proposed scheme (referred to as Gateway Load-Balancing, GWLB) is highly responsive, thanks to fast gateway selection and the fact that current traffic conditions are maintained up-to-date at all times without any overhead. It also effectively takes into account intra-flow and inter-flow interference when switching flows between gateway domains. We have found the performance achievable by routes used after gateway selection to be very close to the performance of optimal routes found by solving a MINLP formulation under the protocol model of interference. Through simulations, we analyze performance and compare with a number of proposed strategies, showing that GWLB outperforms them. In particular, we have observed average flow throughput gains of 128% over the nearest gateway strategy.     

An efficient channel assignment algorithm for multicast wireless mesh networks

Multicast can enhance the performance of wireless mesh networks (WMNs) effectively, which has attracted great attentions in recent years. However, multicast communication in WMNs requires efficient channel assignment strategy to reduce the total network interference and maximize the network throughput. In this paper, the concept of local multicast is proposed to measure interference and solve hidden channel problem in multicast communication. Basing on the concept, we propose a channel assignment algorithm considering the interference of local multicast and forwarding weight of each node (LMFW). The algorithm fully considers partially overlapped channels and orthogonal channels to improve the network performance. Simulations show that the proposed algorithm can reduce interference and improve network capacity of WMNs.     

Design of scalable and efficient multi-radio wireless networks

A proper design of Wireless Mesh Networks (WMNs) is a fundamental task that should be addressed carefully to allow the deployment of scalable and efficient networks. Specifically, choosing strategic locations to optimally place gateways prior to network deployment can alleviate a number of performance/scalability related problems. In this paper, we first, propose a novel clustering based gateway placement algorithm (CBGPA) to effectively select the locations of gateways. Existing solutions for optimal gateway placement using clustering approaches are tree-based and therefore are inherently less reliable since a tree topology uses a smaller number of links. Independently from the tree structure, CBGPA strategically places the gateways to serve as many routers as possible that are within a bounded number of hops. Next, we devise a new multi-objective optimization approach that models WMN topologies from scratch. The three objectives of deployment cost, network throughput and average congestion of gateways are simultaneously optimized using a nature inspired meta-heuristic algorithm coupled with CBGPA. This provides the network operator with a set of bounded-delay trade-off solutions. Comparative simulation studies with different key parameter settings are conducted to show the effectiveness of CBGPA and to evaluate the performance of the proposed model.     

Intelligent wireless mesh path selection algorithm using fuzzy decision making

Wireless mesh networks (WMNs) are expected to be widely deployed due to their ability to provide ubiquity, convenience, cost-efficiency, and simplicity for both service providers and end-users. Recently, the IEEE 802.11s standard introduces the hybrid wireless mesh protocol (HWMP) which is inspired by a combination of on-demand and tree-based pro-active routing algorithms. In this paper, we argue that the proposed unimetric path selection algorithm in the standard is not reliable. We introduce and examine a novel multimetric wireless mesh path selection algorithm using fuzzy decision making under realistic wireless channel conditions. The proposed path selection algorithm is designed to improve the performance of both re-active and pro-active routing protocols of HWMP for not only single-channel but also multi-channel WMNs. The reported results show the superior performance of the proposed path selection algorithm in terms of delay and packet delivery ratio without increasing overhead significantly. Although some fuzzy-based routing algorithms have been defined in literature recently, to the best of our knowledge, this paper is the first one to introduce and examine the use of fuzzy logic in the path selection of single- and multi-channel wireless local area network-based WMNs under realistic wireless channel conditions.     

Secure group communication in wireless mesh networks

Wireless mesh networks (WMNs) have emerged as a promising technology that offers low-cost community wireless services. The community-oriented nature of WMNs facilitates group applications, such as webcast, distance learning, online gaming, video conferencing, and multimedia broadcasting. Security is critical for the deployment of these services. Previous work focused primarily on MAC and routing protocol security, while application-level security has received relatively little attention. In this paper we focus on providing data confidentiality for group communication in WMNs. Compared to other network environments, WMNs present new challenges and opportunities in designing such protocols. We propose a new protocol framework, Secure Group Overlay Multicast (SeGrOM), that employs decentralized group membership, promotes localized communication, and leverages the wireless broadcast nature to achieve efficient and secure group communication. We analyze the performance and discuss the security properties of our protocols. We demonstrate through simulations that our protocols provide good performance and incur a significantly smaller overhead than a baseline centralized protocol optimized for WMNs.