Cluster‐based mobility management algorithms for wireless mesh networks

Wireless mesh networks (WMNs) have been the recent advancements and attracting more academicians and industrialists for their seamless connectivity to the internet. Radio resource is one among the prime resources in wireless networks, which is expected to use in an efficient way especially when the mobile nodes are on move. However, providing guaranteed quality of service to the mobile nodes in the network is a challenging issue. To accomplish this, we propose 2 clustering algorithms, namely, static clustering algorithm for WMNs and dynamic clustering algorithm for WMNs. In these algorithms, we propose a new weight‐based cluster head and cluster member selection process for the formation of clusters. The weight of the nodes in WMN is computed considering the parameters include the bandwidth of the node, the degree of node connectivity, and node cooperation factor. Further, we also propose enhanced quality of service enabled routing protocol for WMNs considering the delay, bandwidth, hopcount, and expected transmission count are the routing metrics. The performance of the proposed clustering algorithms and routing protocol are analyzed, and results show high throughput, high packet delivery ratio, and low communication cost compared with the existing baseline mobility management algorithms and routing protocols.     

无线网状网技术与应用

无线网状网(WMNs)由网状路由器节点和客户机节点组成,其中的网状路由器节点组成了无线网状网的网络骨干,其移动性很小。他们一起为无线网状网和其他常规无线网络的客户机节点提供网络的无线接入。WMNs技术结合了中心式控制的蜂窝网与分布式控制的无线自组织网的优点,可有效克服这两种技术的缺陷并显著提高无线网络的性能,已经成为下一代无线通信网络的研究热点之一。WMNs可为无线个域网、局域网、校园网、城域网的一系列应用提供高速无线宽带接入服务。虽然目前WMNs技术发展很快,但其协议栈各层仍存在许多有待研究的课题。首先简要介绍了无线网状网的结构与特点;随后重点分析了其主要的几个应用领域;最后探讨了WMNs各协议层的研究现状与关键技术,并分析了该技术存在的问题及未来的研究方向。     

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.     

Extending P2PMesh: topology‐aware schemes for efficient peer‐to‐peer data sharing in wireless mesh networks

Wireless mesh networks (WMNs) have emerged as a promising technology that provides low‐cost broadband access to the Internet for fixed and mobile wireless end users. An orthogonal evolution in computer networking has been the rise of peer‐to‐peer (P2P) applications such as P2P data sharing. It is of interest to enable effective P2P data sharing in this type of networks. Conventional P2P data sharing systems are not cognizant of the underlying network topology and therefore suffer from inefficiency. We argue for dual‐layer mesh network architecture with support from wireless mesh routers for P2P applications. The main contribution of this paper is P2PMesh: a topology‐aware system that provides combined architecture and efficient schemes for enabling efficient P2P data sharing in WMNs. The P2PMesh architecture utilizes three schemes: (i) an efficient content lookup that mitigates traffic load imbalance at mesh routers; (ii) an efficient establishment of download paths; and (iii) a data transfer protocol for multi‐hop wireless networks with limited capacity. We note here that the path establishment and data transfer schemes are specific to P2P traffic and that other traffic would use routes determined by the default routing protocol in the WMN. Simulation results suggest that P2PMesh has the potential to improve the performance of P2P applications in a wireless multi‐hop setting; specifically, we focused on data sharing, but other P2P applications can also be supported by this approach. Copyright © 2011 John Wiley & Sons, Ltd.     

A ring-based multicast routing topology with QoS support in wireless mesh networks

Wireless mesh networking (WMN) is an emerging technology for future broadband wireless access. The proliferation of the mobile computing devices that are equipped with cameras and ad hoc communication mode creates the possibility of exchanging real-time data between mobile users in wireless mesh networks. In this paper, we argue for a ring-based multicast routing topology with support from infrastructure nodes for group communications in WMNs. We study the performance of multicast communication over a ring routing topology when 802.11 with RTS/CTS scheme is used at the MAC layer to enable reliable multicast services in WMNs. We propose an algorithm to enhance the IP multicast routing on the ring topology. We show that when mesh routers on a ring topology support group communications by employing our proposed algorithms, a significant performance enhancement is realized. We analytically compute the end-to-end delay on a ring multicast routing topology. Our results show that the end-to-end delay is reduced about 33 %, and the capacity of multicast network (i.e., maximum group size that the ring can serve with QoS guarantees) is increased about 50 % as compared to conventional schemes. We also use our analytical results to develop heuristic algorithms for constructing an efficient ring-based multicast routing topology with QoS guarantees. The proposed algorithms take into account all possible traffic interference when constructing the multicast ring topology. Thus, the constructed ring topology provides QoS guarantees for the multicast traffic and minimizes the cost of group communications in WMNs.     

无线Mesh网中基于信道感知的多径路由判据

无线Mesh网是一种新型的宽带无线接入网络,其中路由算法的设计是一个非常活跃的研究领域。WCETT路由判据仅适于单径路由协议,但是多路径路由能够提供负载平衡和较高的总带宽。为了提高网络性能,在综合考虑无线链路质量和信道间干扰的基础上,提出了一种新的多径路由判据CAM-WCETT。仿真结果表明,该方案能显著提高网络的吞吐量。     

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.     

Unified routing protocol based on passive bandwidth measurement in heterogeneous WMNs

The past few years have witnessed a surge of wireless mesh networks (WMNs)‐based applications and heterogeneous WMNs are taking advantage of multiple radio interfaces to improve network performance. Although many routing protocols have been proposed for heterogeneous WMNs, most of them mainly relied on hierarchical or cluster techniques, which result in high routing overhead and performance degradation due to low utilization of wireless links. This is because only gateway nodes are aware of all the network resources. In contrast, a unified routing protocol (e.g., optimal link state routing (OLSR)), which treats the nodes and links equally, can avoid the performance bottleneck incurred by gateway nodes. However, OLSR has to pay the price for unification, that is, OLSR introduces a great amount of routing overhead for broadcasting routing message on every interface. In this paper, we propose unified routing protocol (URP), which is based on passive bandwidth measurement for heterogeneous WMNs. Firstly, we use the available bandwidth as a metric of the unification and propose a low‐cost passive available bandwidth estimation method to calculate expected transmission time that can capture the dynamics of wireless link more accurately. Secondly, based on the estimated available bandwidth, we propose a multipoint relays selection algorithm to achieve higher transmission ability and to help accelerate the routing message diffusion. Finally, instead of broadcasting routing message on all channels, nodes running URP transmit routing message on a set of selected high bandwidth channels. Results from extensive simulations show that URP helps improve the network throughput and to reduce the routing overhead compared with OLSR and hierarchical routing. Copyright © 2016 John Wiley & Sons, Ltd.     

On Routing in Multichannel Wireless Mesh Networks: Challenges and Solutions

Wireless mesh networks have emerged as a promising solution to providing cost-effective last-mile connectivity. Employing multiple channels is shown to be an effective approach to overcoming the problem of capacity degradation in multihop wireless networks. However, existing routing schemes that are designed for single-channel multihop wireless networks may lead to inefficient routing paths in multichannel WMNs. To fully exploit the capacity gain due to multiple channels, one must consider the availability of multiple channels and distribute traffic load among channels as well as among nodes in routing algorithms. In this article we focus on the routing problem in multichannel WMNs. We highlight the challenges in designing routing algorithms for multichannel WMNs and examine existing routing metrics that are designed for multichannel WMNs, along with a simulation-based performance study. We also address some open research issues related to routing in multichannel WMNs.     

A Role Based Privacy-Aware Secure Routing Protocol for Wireless Mesh Networks

Wireless Mesh Networks (WMNs) have drawn much attention for emerging as a promising technology to meet the challenges in next generation networks. Security and privacy protection have been the primary concerns in pushing towards the success of WMNs. There have been a multitude of solutions proposed to ensure the security of the routing protocol and the privacy information in WMNs. However, most of them are based on the assumptions that all nodes cooperate with routing and forwarding packets and the attacks are from outside. In order to defend against the internal attacks and to achieve better security and privacy protection, this paper proposes a role based privacy-aware secure routing protocol (RPASRP), which combines a new dynamic reputation mechanism with the role based multi-level security technology and a hierarchical key management protocol. Simulation results show that RPASRP implements the security and privacy protection against the inside attacks more effectively and efficiently and performs better than the classical hybrid wireless mesh protocol in terms of packet delivery ratio and average route length.     

Fair Allocation of Subcarrier and Power in an OFDMA Wireless Mesh Network

This paper presents a new fair scheduling scheme for orthogonal frequency-division multiple-access-based wireless mesh networks (WMNs), which fairly allocates subcarriers and power to mesh routers (MRs) and mesh clients to maximize the Nash bargaining solution fairness criterion. In WMNs, since not all the information necessary for scheduling is available at a central scheduler (e.g., MR), it is advantageous to involve the MR and as many mesh clients as possible in distributed scheduling based on the limited information that is available locally at each node. Instead of solving a single global control problem, we hierarchically decouple the subcarrier and power allocation problem into two subproblems, where the MR allocates groups of subcarriers to the mesh clients, and each mesh client allocates transmit power among its subcarriers to each of its outgoing links. We formulate the two subproblems by nonlinear integer programming and nonlinear mixed integer programming, respectively. A simple and efficient solution algorithm is developed for the MR's problem. Also, a closed-form solution is obtained by transforming the mesh client's problem into a time-division scheduling problem. Extensive simulation results demonstrate that the proposed scheme provides fair opportunities to the respective users (mesh clients) and a comparable overall end-to-end rate when the number of mesh clients increases     

An efficient cooperative hybrid routing protocol for hybrid wireless mesh networks

Hybrid wireless mesh networks are the most generic types of wireless mesh networks. Unlike static mesh routers, which have multiple radio interfaces and almost no energy constraint, mobile mesh clients are usually equipped with a single radio interface and have energy limitations. A cooperative hybrid routing protocol (CHRP) combining advantages of proactive and reactive routing protocols by letting them work cooperatively is proposed in this paper, which can adapt to features of both routers and clients. In CHRP, in order to make a proper route selection, channel condition, interference and constrained energy of clients are considered in the node-aware routing metric. Besides, a cross-layer approach is used in CHRP. Both gateway and client oriented data flows are considered comprehensively. The simulation results using ns-3 show the advantage of the proposed CHRP in terms of average packet loss rate, average latency, average network throughput, average energy consumption of clients and the minimum residual energy of clients.     

A Hybrid Centralized Routing Protocol for 802.11s WMNs

Wireless mesh networks (WMNs) are being widely accepted as a critical wireless access solution for various applications. Due to minimal mobility in mesh nodes, a backbone topology can be effectively maintained in WMN using a proactive routing protocol. In IEEE 802.11s standard, a tree-based routing (TBR) protocol is adopted as a viable proactive routing protocol for a WMN with user traffic flowing to/from a wired network through a root (i.e., a mesh portal). However, the performance of the TBR protocol degrades rapidly as the user traffic becomes dominated by intra-mesh traffic. The reason is that the routing path through the root even for intra-mesh traffic unnecessarily overloads the root. Furthermore, the TBR performance becomes more severe when the network size of WMN is large, which could lead to the huge amount of intra-mesh traffic towards the root. To overcome these problems, we propose a new routing mechanism, root driven routing (RDR) protocol, for the root to quickly determine the best-metric route for any source-destination pair of intra-mesh traffic. For inter-mesh traffic, the original TBR protocol is employed. Thus, the hybrid centralized routing protocol that combines TBR and RDR and is adaptive to all traffic scenarios. Our simulation results reveal that the proposed RDR protocol outperforms the TBR protocol with much lower average end-to-end delay and much higher packet delivery ratio for intra-mesh traffic. The simulation results also provide some insight into the right tradeoff between the TBR protocol and the RDR protocol to achieve the best performance of the hybrid centralized routing protocol for WMNs.     

Efficient routing for wireless mesh networks using a backup path

Wireless mesh networks (WMNs) have a proven record in providing viable solutions for some of the fundamental issues in wireless networks such as capacity and range limitations. WMN infrastructure includes clusters of mobile ad‐hoc networks connected through a fixed backbone of mesh routers. The mesh network can be constrained severely because of various reasons, which could result in performance degradation such as a drop in throughput or long delays. Solutions to this problem often focus on multipath or multichannel extensions to the existing ad‐hoc routing protocols. In this paper, we propose a novel solution by introducing an alternative path to the mesh backbone that traverses the mobile ad‐hoc networks part of the WMN. The new routing solution allows the mobile nodes (MNs) to establish direct communication among peers without going through the backbone. The proposed alternative ad‐hoc path is used only when the mesh backbone is severely constrained. We also propose, for the first time in WMNs, using MNs with two interfaces, one used in the mesh backbone communication and the other engaged in the ad‐hoc network. A scheme is presented for making the MN aware of link quality measures by providing throughput values to the ad‐hoc on‐demand distance vector protocol. We use piggybacking on route reply messages in ad‐hoc on‐demand distance vector to avoid incurring additional costs. We implemented our solution in an OPNET simulator and evaluated its performance under a variety of conditions. Simulation results show that the alternative ad‐hoc path provides higher throughput and lower delays. Delay analysis show that the throughput improvement does not impose additional costs. Copyright © 2012 John Wiley & Sons, Ltd.     

Cross Layer Secure and Resource-Aware On-Demand Routing Protocol for Hybrid Wireless Mesh Networks

Secure routing is one of the challenges offered by hybrid wireless mesh networks (WMNs). Researcher are implementing different approaches for mesh routing, but still need more efforts in terms of security, efficiency, deployment and capability with different scenarios and applications. Cross layer secure and resource-aware on demand routing (CSROR) protocol for hybrid WMN is designed to ensure routing security and fulfil different applications specific requirements for multimedia delivery and real-time transmissions. CSROR selects an optimum route on the basis of route security taking in consideration the different cross layer parameters. CSROR is not only resource aware approach but also resilient to different packet dropping attacks. It is evaluated in diverse range of hostile hybrid WMN scenarios.     

Social-aware dynamic router node placement in wireless mesh networks

The problem of dynamic router node placement (dynRNP) in wireless mesh networks (WMNs) is concerned with determining a dynamic geographical placement of mesh routers to serve mobile mesh clients at different times, so that both network connectivity (i.e., the greatest topology subgraph component size) and client coverage (i.e., the number of the served mesh clients) are maximized. Mesh clients are wireless devises associated with users, and in real world, the users with same interests or some social relationship have higher chance to gather and move together geographically, i.e., they form a community, and the WMN with multiple communities can be regarded as a social network. Therefore, this paper investigates the so-called social-aware WMN-dynRNP problem assuming that mesh routers should be aware of the social community structure of mesh clients to dynamically adjust their placement to improve network performance. To cope with this problem, this paper proposes a social-based particle swarm optimization approach, which additionally includes a social-supporting vector to direct low-loading mesh routers to support the heavy-loading mesh routers in the same topology subgraph component (community), so as to dynamically adopt to the social community behavior of mesh clients. As compared with the previous approach, our experimental results show that the proposed approach is capable of effectively reducing number of the unserved mesh clients and increasing network connectivity in dynamic social scenarios.     

A QoS aware joint design for wireless mesh networks

Wireless mesh networks (WMNs) provide Internet access to remote areas and wireless connections on a metropolitan scale. In this paper, we focus on the problem of improving the gateway throughput in WMNs while achieving fairness and supporting quality-of-service (QoS) differentiation for end-users. To address this problem, we propose a new distributed dynamic traffic scheduling algorithm that supports different QoS requirements from different users. We also develop a joint weight-aware channel assignment and minimum expected delay routing mechanism. Simulation results demonstrate the performance of the proposed work in terms of the achieved throughput and minimized packet loss ratio and delay.     

WMN中一种基于干扰感知的负载均衡路由协议

无线信道干扰和负载分布的不均衡严重影响无线Mesh网络吞吐量、端到端延时和资源利用率。在已有基于信噪比和邻居节点个数的干扰模型基础上,进一步研究了无线Mesh网络的链路干扰。在综合考虑了无线Mesh网络流间干扰和和流内干扰的基础上,提出路由判据PIL（Path Interfer-ence Level）。在此基础上,提出一种新的基于干扰感知的负载均衡路由协议IA-DSR（Interference-Aware DSR）。IA-DSR考虑无线网络拥塞并选择受到干扰最小的路径。仿真结果表明,在不显著增加开销的情况下,IA-DSR可以有效地提高网络的整体吞吐量,降低网络端到端时延和丢包率。     

CAKA: a novel certificateless-based cross-domain authenticated key agreement protocol for wireless mesh networks

Due to the flexibility of wireless mesh networks (WMNs) to form the backhaul subnetworks, future generation networks may have to integrate various kinds of WMNs under possibly various administrative domains. Aiming at establishing secure access and communications among the communication entities in a multi-domain WMN environment, in this paper, we intend to address the cross-domain authentication and key agreement problem. We present a light-weight cross-domain authentication and key agreement protocol, namely CAKA, under certificateless-based public key cryptosystem. CAKA has a few attractive features. First, mutual authentication and key agreement between any pair of users from different WMN domains can be easily achieved with two-round interactions. Second, no central domain authentication server is required and fast authentication for various roaming scenarios is supported by using a repeated cross-domain algorithm. Third, no revocation and renewal of certificates and key escrow are needed. Finally, it provides relatively more security features without increasing too much overhead of computation and storage. Our analysis shows that the proposed CAKA protocol is highly efficient in terms of communication overhead and resilient to various kinds of attacks.     

Design and Performance Study for a Mobility Management Mechanism (WMM) Using Location Cache for Wireless Mesh Networks

Wireless mesh networks (WMNs) have emerged as one of the major technologies for 4G high-speed mobile networks. In a WMN, a mesh backhaul connects the WMN with the Internet, and mesh access points (MAPs) provide wireless network access service to mobile stations (MSs). The MAPs are stationary and connected through the wireless mesh links. Due to MS mobility in WMNs, mobility management (MM) is required to efficiently and correctly route the packets to MSs. We propose an MM mechanism named Wireless mesh Mobility Management (WMM). The WMM adopts the location cache approach, where mesh backhaul and MAPs (referred to as mesh nodes (MNs)) cache the MS's location information while routing the data for the MS. The MM is exercised when MNs route the packets. We implement the WMM and conduct an analytical model and simulation experiments to investigate the performance of WMM. We compare the signaling and routing cost between WMM and other existing MM protocols. Our study shows that WMM has light signaling overhead and low implementation cost.