Mobility-Aware Mobile Router Selection and Address Management for IPv6 Network Mobility

Network mobility (NEMO) extends IP mobility to moving networks, which are groups of nodes that often constitute a subnet of a mobile router (MR). To realize this collective mobility, there are a number of important issues such as addressing and multihoming. With the proliferation of mobile nodes connected to the Internet, the efficient allocation/deallocation of addresses is becoming a vital requirement. We propose a collaborative address management scheme for network mobility, where the home DHCPv6 agent of a mobile network performs prefix delegation, while the mobile DHCPv6 agent (in the mobile network) allocates the IPv6 address to each mobile node. Also, network mobility with multiple MRs is taken into consideration. To provide a mobile network that has multiple MRs with robust Internet connectivity, we propose mobility-aware mobile router selection schemes. The concept of mobility awareness refers to the capability of a moving network in a vehicle (e.g., a train) to pinpoint the most stable Internet connectivity, by choosing the mobile router based on the vehicles movement pattern. The simulation shows that the proposed scheme outperforms a round-robin mobile router selection scheme in terms of the amount of carried traffic.     

Design and implementation of MobiSEC: A complete security architecture for wireless mesh networks

Wireless mesh networks (WMNs) have emerged recently as a technology for next-generation wireless networking. They consist of mesh routers and clients, where mesh routers are almost static and form the backbone of WMNs. WMNs provide network access for both mesh and conventional clients.In this paper we propose MobiSEC, a complete security architecture that provides both access control for mesh users and routers as well as a key distribution scheme that supports layer-2 encryption to ensure security and data confidentiality of all communications that occur in the WMN.MobiSEC extends the IEEE 802.11i standard exploiting the routing capabilities of mesh routers; after connecting to the access network as generic wireless clients, new mesh routers authenticate to a central server and obtain a temporary key that is used both to prove their credentials to neighbor nodes and to encrypt all the traffic transmitted on the wireless backbone links.A key feature in the design of MobiSEC is its independence from the underlying wireless technology used by network nodes to form the backbone. Furthermore, MobiSEC allows seamless mobility of both mesh clients and routers.MobiSEC has been implemented and integrated in MobiMESH, a WMN implementation that provides a complete framework for testing and analyzing the behavior of a mesh network in real-life environments. Moreover, extensive simulations have been performed in large-scale network scenarios using Network Simulator.Numerical results show that our proposed architecture considerably increases the WMN security, with a negligible impact on the network performance, thus representing an effective solution for wireless mesh networking.     

基于P2P的无线mesh网移动性管理研究

无线Mesh网是一种新型的无线组网技术,现有的无线移动管理协议还不能在这一网络结构上直接适用.在典型无线mesh网络分层结构模型上,对现有的几种无线网络移动管理协议进行了比较,并且针对无线mesh网的结构特点提出了一种大型无线mesh网络下的移动性管理方案,采用了基于P2P的分层结构实现网络移动定位信息的自动注册、自动管理和快速查询,同时网络具有较好的负载均衡和抗毁性能.仿真结果表明,与传统的分层移动管理协议相比,该方案可以得到更优化的移动路由.     

Load-aware routing in mesh networks: Models, algorithms and experimentation

In this paper we consider wireless mesh networks (WMNs) used to share the Internet connectivity of sparsely deployed fixed lines with heterogeneous capacity, ranging from ISP-owned high-speed links to subscriber-owned low-speed connections. If traffic is routed in the mesh without considering the load distribution and the bandwidth of Internet connections, some gateways may rapidly get overloaded because they are selected by too many mesh nodes. This may cause a significant reduction of the overall network capacity. To address this issue, in this paper we first develop a queuing network model that predicts the residual capacity of network paths, and identifies network bottlenecks. By taking advantage of this model, we design a novel Load-Aware Route Selection algorithm, named LARS, which improves the network capacity by allocating network paths to upstream Internet flows so as to ensure a more balanced utilization of wireless network resources and gateways’ Internet connections. Using simulations and a prototype implementation, we show that the LARS scheme significantly outperforms the shortest-path first routing protocol using a contention-aware routing metric, providing up to 240% throughput improvement in some network scenarios.     

Routing Internet traffic in heterogeneous mesh networks: Analysis and algorithms

In practical wireless mesh networks (WMNs), gateways are subject to hard capacity limits on the aggregate number of flows (in terms of bit rate) that they can support. Thus, if traffic is routed in the mesh network without considering those constraints, as well as the traffic distribution, some gateways or intermediate mesh routers may rapidly get overloaded, and the network resources can be unevenly utilized. To address this problem, in this paper we firstly develop a multi-class queuing network model to analyze feasible throughput allocations, as well as average end-to-end delay, in heterogeneous WMNs. Guided by our analysis, we design a Capacity-Aware Route Selection algorithm (CARS), which allocates network paths to downstream and upstream Internet flows so as to ensure a more balanced utilization of wireless network resources and gateways’ fixed connections. Through simulations in a number of different network scenarios we show that the CARS scheme significantly outperforms conventional shortest path routing, as well as an alternative routing method that distributes the traffic load on the gateway nodes to minimize its variance.     

基于Grover搜索的无线Mesh网流量均衡路由算法

在无线Mesh网(WMN)应用中,用户通过Mesh网关接入到Internet,这种结构容易导致不同位置的Mesh路由器通过的流量不均衡,使部分路由器成为瓶颈,从而影响网络的性能和用户的服务质量(QoS)。针对这一问题,提出了一种基于Grover量子搜索算法的无线Mesh网流量均衡路由算法。算法中利用了量子计算的并行性,根据流量均衡函数模型构建了操作矩阵,通过Grover迭代获得流量均衡路径。仿真表明,算法选择的路径可以有效地平衡无线Mesh网流量,使每用户获得的最小带宽最大化,执行效率也优于同类算法。     

A hierarchical architecture for detecting selfish behaviour in community wireless mesh networks

Wireless mesh networks (WMNs) consist of dedicated nodes called mesh routers which relay the traffic generated by mesh clients over multi-hop paths. In a community WMN, all mesh routers may not be managed by an Internet Service Provider (ISP). Limited capacity of wireless channels and lack of a single trusted authority in such networks can motivate mesh routers to behave selfishly by dropping relay traffic in order to provide a higher throughput to their own users. Existing solutions for stimulating cooperation in multi-hop networks use promiscuous monitoring or exchange probe packets to detect selfish nodes and apply virtual currency mechanism to compensate the cooperating nodes. These schemes fail to operate well when applied to WMNs which have a multi-radio environment with a relatively static topology. In this paper we, propose architecture for a community WMN which can detect selfish behaviour in the network and enforce cooperation among mesh routers. The architecture adopts a decentralized detection scheme by dividing the mesh routers into manageable clusters. Monitoring agents hosted on managed mesh routers monitor the behaviour of mesh routers in their cluster by collecting periodic reports and sending them to the sink agents hosted at the mesh gateways. To make the detection more accurate we consider the quality of wireless links. We present experimental results that evaluate the performance of our scheme.     

WMN中的干扰避免部分重叠信道分配算法

针对无线mesh网络(wireless mesh networks,WMN)中存在的信道干扰问题,提出一种基于部分重叠信道(partially overlapping channels,POC)的负载平衡且干扰避免的信道分配算法。通过基于Huffman树的通信接口分配方法连接邻居节点的接口;根据网络干扰情况,对链路进行迭代信道分配,使用静态链路调度保证网络连接;利用启发式算法优先为重要程度较高的链路分配无干扰时隙,对链路调度进行优化。仿真结果表明,在具有混合流量的WMN中,所提算法可以显著提升网络吞吐量,降低网络干扰与平均丢包率,改善网络性能。     

Interworking wireless mesh networks: Problems,performance characterization,and perspectives

Wireless broadband networks based on the IEEE 802.11 technology are being increasingly deployed as mesh networks to provide users with extended coverage for wireless Internet access. These wireless mesh networks, however, may be deployed by different authorities without any coordination a priori, and hence it is possible that they overlap partially or even entirely in service area, resulting in contention of radio resources among them. In this paper, we investigate the artifacts that result from the uncoordinated deployment of wireless mesh networks. We use a network optimization approach to model the problem as resource sharing among nodes belonging to one or different networks. Based on the proposed LP formulation, we then conduct simulations to characterize the performance of overlaying wireless mesh networks, with the goal to provide perspectives for addressing the problems. We find that in a system with multiple overlaying wireless mesh networks, if no form of inter-domain coordination is present, individual mesh networks could suffer from capacity degradation due to increased network contention. One solution toward addressing the performance degradation is to “interwork” these wireless mesh networks by allowing inter-domain traffic relay through provisioning of “bridge” nodes. However, if such bridge nodes are chosen arbitrarily, the problems of throughput sub-optimality and unfairness may arise. We profile the impact of bridge node selection and show the importance in controlling network unfairness for wireless mesh network interworking. We conclude that mesh network interworking is a promising direction to address the artifacts due to uncoordinated deployment of wireless mesh networks if it is supplemented with appropriate mechanisms.     

Adaptive per-user per-object cache consistency management for mobile data access in wireless mesh networks

We propose and analyze an adaptive per-user per-object cache consistency management (APPCCM) scheme for mobile data access in wireless mesh networks. APPCCM supports strong data consistency semantics through integrated cache consistency and mobility management. The objective of APPCCM is to minimize the overall network cost incurred due to data query/update processing, cache consistency management, and mobility management. In APPCCM, data objects can be adaptively cached at the mesh clients directly or at mesh routers dynamically selected by APPCCM. APPCCM is adaptive, per-user and per-object as the decision regarding where to cache a data object accessed by a mesh client is made dynamically, depending on the mesh client’s mobility and data query/update characteristics, and the network’s conditions. We develop analytical models for evaluating the performance of APPCCM and devise a computational procedure for dynamically calculating the overall network cost incurred. We demonstrate via both model-based analysis and simulation validation that APPCCM outperforms non-adaptive cache consistency management schemes that always cache data objects at the mesh client, or at the mesh client’s current serving mesh router for mobile data access in wireless mesh networks.     

Traffic Prediction for Reliable and Resilient Video Communications Over Multi-Location WMNs

This paper studies reliable and resilient deployment of video over IP across a multi-location organization, where a number of wireless mesh network (WMN) clouds are connected by a virtual private network (VPN). Particularly, we propose a scheme of enhanced SIP proxy server which can support an accountable network. In our proposed solution, the enhanced SIP proxy server consists of three modules, namely traffic load prediction, VPN bandwidth negotiation, and call admission control (CAC) in order to provide trustable service. We identify traffic load prediction as the key component among the three modules, and we further develop a linear predictor of variable sampling rate-normalized least mean square (VSR-NLMS) to estimate the traffic patterns. VSR-NLMS predictor employs adjustable sampling rate to achieve improved efficiency and performance. Numerical results show that our proposed scheme can automatically choose suitable sampling rate to track and predict the traffic load curve with acceptable accuracy and reasonable computational complexity.     

Load-balanced AP association in multi-hop wireless mesh networks

Wireless mesh networks (WMNs) provide high-bandwidth wireless access, which makes it capable for multimedia services. A user in a WMN may be covered by multiple APs, while it should be associated with only one to access the Internet. Conventional IEEE 802.11 user-AP association mechanism for WLANs employs signal strength as the sole metric. However, this may lead to network congestion and performance degradation in multi-hop networks such as WMNs, especially for multimedia services that require a large bandwidth and a low latency. Thus AP association in WMNs becomes an important research issue. In this paper we propose a novel AP association approach LBAA, taking AP’s load-balancing, WMN’s multi-hop characteristic, and user’s RSSI into consideration. We first propose a centralized algorithm and then extend it to a distributed one, with the latter one more practical and convenient for deployment. Network throughput and max–min user fairness are improved by LBAA. Performance evaluation demonstrating the benefits of our approach is given through a series of experiments in terms of collision probability, access bandwidth, end-to-end throughput, and average RSSI.     

Experimentation and performance analysis of multi-interfaced mobile router scheme

Network mobility (NEMO) aims providing seamless Internet connectivity of the whole mobile network that consists of mobile routers (MRs) and mobile network nodes (MNNs). The network moves around along with vehicles as a whole. According to NEMO basic support protocol (NEMO BSP), only one primary care of address (CoA) of MR can be registered with home agent, which will affect the handover performance. As an extension of NEMO BSP, multiple care of addresses (MCoA) registration scheme was proposed as Internet-draft and has received extensive researches.This paper studies the Internet connectivity of mobile router (MR) on the basis stated above; MR is equipped with WLAN, CDMA and GPRS interfaces simultaneously. Concretely, a smooth handover algorithm is proposed and experimented on our platform successfully; round trip time (RTT) of each link and the handover process between different interfaces are analyzed, respectively. Furthermore, the service disruption time and packet loss ratio performances are also compared between uni-interfaced MR scheme of NEMO BSP and scheme proposed in this paper, and the results indicate that multi-interfaced scheme not only supports large area movement across heterogeneous networks of MR, it also provides a seamless handover with no packet loss and little service disruption time.     

Design of certification authority using secret redistribution and multicast routing in wireless mesh networks

Wireless mesh networks (WMNs) should provide authentication and key management without a trusted third party because of their self-organizing and self-configuring characteristics. Several solutions to this problem have been proposed in mobile ad hoc networks (MANETs). But they are not optimal for WMNs because WMNs are with stationary mesh routers (MRs) that do not suffer from the limited power problem. In this paper, we design an architecture of mesh certification authority (MeCA) for WMNs. In MeCA, the secret key and functions of certification authority (CA) are distributed over several MRs. For secret sharing and redistribution, we develop the fast verifiable share redistribution (FVSR) scheme, which works for threshold cryptography and minimizes the possibility of secret disclosure when some shareholders are compromised by adversaries. MeCA adopts the multicasting based on Ruiz tree, which is optimal in reducing the operation overhead. It can update, revoke, and verify certificates of WMN nodes in a secure and efficient manner. Simulation results show that MeCA does not disclose its secret key even under severe attacks while incurring low overhead compared to other existing schemes in MANETs.     

骨干无线网状网的排队延迟性能研究

对一种基于网状分布的骨干无线网状网的延迟性能进行研究.提出了一种基于均衡负载的最短路径路由协议.在此协议基础上,研究了无线网状网数据包的排队延迟,推导出无线网状网排队延迟与网络的规模、网关和网状路由器的服务能力、数据包到达率的相互关系.此外,还分析排队延迟和网络容量的相互制约关系,并给出了在延迟限制条件下的网络容量.     

Multi-portal association based dispatching and a virtual-queue method in wireless mesh networks

Single-portal association has long been adopted as the basic assumption in wireless mesh network (WMN) research. Whereas this assumption can simplify the overall design, it cannot meet the increasing growth of traffic volume. We propose the use of multi-portal association in this paper, which allows traffic to go through multiple mesh portals so as to ease the performance bottleneck problem caused by single-portal association. We propose the multi-portal association scheme, and a method using the virtual-queue concept to support traffic dispatching within such multi-portal association scheme. The operation of the virtual-queue method is based on the centralized link state estimation and virtual queue emulation. The simulation results show that the proposed multi-portal association outperforms the conventional single-portal association. For the UDP traffic, in the simple-structured and short-distanced networks, the use of multi-portal association (with the virtual-queue dispatching method) is able to reduce 99% of packet loss and increase 500% of throughput, when comparing to the case of using single-portal association. In the more-complex structured networks, it can provide 60% reduction in packet loss and achieve 1500% increase of throughput. On the other hand, for the TCP traffic, in the simple-structured networks, the proposed solution can achieve 92% reduction in latency and 91% increase of throughput.     

Throughput-coverage tradeoff in a scalable wireless mesh network

The wireless mesh network (WMN) is an economical and low-power solution to support ubiquitous broadband services. However, mesh networks face scalability and throughput bottleneck issues as the coverage and the number of users increase. Specifically, if the coverage is extended by multiple hops, the repeatedly relayed traffic will exhaust the radio resource and degrade user throughput. Meanwhile, as the traffic increases because of more users, the throughput bottleneck will occur at the users close to the gateway. The contention collisions among these busy users near the gateway will further reduce user throughput. In this paper, a newly proposed scalable multi-channel ring-based WMN is employed. Under the ring-based cell structure, multi-channel frequency planning is used to reduce the number of contending users at each hop and overcome the throughput bottleneck issue, thereby making the system more scalable to accommodate more users and facilitate coverage extension. This paper mainly focuses on investigating the overall tradeoffs between user throughput and cell coverage in the ring-based WMN. An analytical throughput model is developed for the ring-based WMN using the carrier sense multiple access (CSMA) medium access control (MAC) protocol. In the analysis, we also develop a bulk-arrival semi-Markov queueing model to describe user behavior in a non-saturation condition. On top of the developed analytical model, a mixed-integer nonlinear optimization problem is formulated, aiming to maximize cell coverage and capacity. Applying this optimization approach, we can obtain the optimal number of rings and the associated ring widths of the ring-based WMN.     

Securing wireless mesh networks in a unified security framework with corruption-resilience

Wireless mesh networks (WMN) are expected to be widespread due to their excellent properties like low-cost deployment, easy arrangement and self-organization. Although some proposed security schemes for WMNs with various security objectives have been put forward recently, it is a challenge to employ a uniform cryptography context to achieve resilience to trust authority corruption and maintain trust relationships flexibly among different domains. In this paper, a unified security framework (USF) for multi-domain wireless mesh networks is proposed. The identity-based encryption and the certificateless signature are unified in the proposed cryptography operations utilizing bilinear groups to solve key escrow problem. To ensure secure muliti-hop communication in WMN, the intra and inter domain authentication and key agreement protocols are devised sophisticatedly to achieve perfect forward secrecy and attack-resilience. With the enhanced security properties in the USF scheme, when a trust authority is corrupted, parts of the WMN could be survivable in the local area if proper measures are taken. A formal security proof of the proposed authentication protocols is presented based on Universal Composable security theory. The detailed performance analysis shows that the enhanced security attributes are achieved with reasonable overhead.     

A mobility management scheme for wireless mesh networks based on a hybrid routing protocol

Recent advances in wireless mesh networks (WMNs) have overcome the drawbacks of traditional wired networks and wireless ad hoc networks. WMNs will play a leading role in the next generation of networks, and the question of how to provide seamless mobility management for WMNs is the driving force behind the research. The inherent characteristics of WMNs, such as relatively static backbones and highly mobile clients, require new mobility management solutions to be designed and implemented.In this paper, a hybrid routing protocol for forwarding packets is proposed: this involves both link layer routing and network layer routing. Based on the hybrid routing protocol, a mobility management scheme for WMNs is presented. Both intra-domain and inter-domain mobility management have been designed to support seamless roaming in WiFi-based WMNs. During intra-domain handoff, gratuitous ARP messages are used to provide new routing information, thus avoiding re-routing and location update. For inter-domain handoff, redundant tunnels are removed in order to minimize forwarding latency. Comprehensive simulation results illustrate that our scheme has low packet latency, low packet loss ratio and short handoff latency. As a result, real-time applications over 802.11 WMNs such as VoIP can be supported.     

基于双向强化学习与动态码率调节的无线mesh网络协议

针对现有无线mesh网络协议的用户体验质量(QoE)较差的问题,提出一种基于双向强化学习与动态码率调节的无线mesh网络协议。首先,设计了兼容不同服务类型的无线mesh网络QoE度量框架;然后,设计了基于双向强化学习的无线mesh网络路由协议;最终,结合QoE感知的差异化报文调度策略与数据流源节点码率动态调节算法进一步优化终端用户的QoE质量。基于NS-2仿真平台的对比实验结果显示,本协议可明显地提高无线mesh网络的QoE指标,同时具有较低的控制开销。