Mesh Routers Research Articles

Optimal Deployment and Traffic Flows in Mobile Mesh Network after a Disaster

It is a critical research problem to quickly reconstruct a communication system after a disaster. One resolution is to deploy mobile mesh routers (MMR) in the disaster area to guarantee the connection of users. However, it is still a challenge to find an optimal deployment of MMRs to maximally satisfy users while ensuring a fluent and reliable communication network. In this paper, we focus on the above problems and propose a communication-demand-oriented deployment method (CDODM) and a global-data-traffic routing optimisation method (GTFROM) for a disaster. Our main contributions are (1) formalisation and optimisation of computation transmission cost in CDODM and (2) formalisation and optimisation traffic flows in GTFROM. Through the evaluation in NS3, user satisfaction calculated based on recorded throughput in NS3 can be enhanced clearly in the proposed solutions. In scalability study, the proposed methods works well, with changing range of disaster areas, number of MMRs and communication demands.

Optimal deployment and traffic flows in mobile mesh network after a disaster

It is a critical research problem to quickly reconstruct a communication system after a disaster. One resolution is to deploy mobile mesh routers (MMR) in the disaster area to guarantee the connection of users. However, it is still a challenge to find an optimal deployment of MMRs to maximally satisfy users while ensuring a fluent and reliable communication network. In this paper, we focus on the above problems and propose a communication-demand-oriented deployment method (CDODM) and a global-data-traffic routing optimisation method (GTFROM) for a disaster. Our main contributions are (1) formalisation and optimisation of computation transmission cost in CDODM and (2) formalisation and optimisation traffic flows in GTFROM. Through the evaluation in NS3, user satisfaction calculated based on recorded throughput in NS3 can be enhanced clearly in the proposed solutions. In scalability study, the proposed methods works well, with changing range of disaster areas, number of MMRs and communication demands.

A trustworthy and energy-aware routing protocol in software-defined wireless mesh networks

Hybrid Wireless Mesh Networks (HWMNs) were proposed to address the challenges in wireless communications to support mobile applications across different domains. Due to the multi-hop and decentralized network architecture, HWMNs are naturally susceptible to various security threats, especially internal attacks. Therefore, HWMNs must be able to detect anomalies, provide secure routing and protect user privacy through the cooperation among nodes. However, the existing routing protocols for HWMNs cannot ensure the security to protect the users privacy effectively. Moreover, traditional HWMNs are vertically integrated where the control and data planes of mesh routers are bundled together, which makes it complex and difficult to configure the network according to predefined security policies, and to adaptively respond to various dynamic security threats. Software-Defined Wireless Mesh Networks decouple the control plane and data plane of routers and thus enable a more flexible and efficient configuration of security policies. Taking up this opportunity to address the aforementioned challenges, this paper proposes a privacy-aware, secure and energy-aware green routing (PSGR) protocol that can defend against internal attacks, achieve stronger privacy protection and reduce energy consumption in Software-Defined HWMNs. The elaborate theoretical analysis verify that the PSGR protocol can implement the security and privacy protection against internal attacks effectively and efficiently. Simulation results demonstrate a superior performance of PSGR in terms of packet delivery ratio, network throughput and energy efficiency compared to the existing PA-SHWMP, PASER, and HWMP protocols in the presence of Blackhole/Grayhole attacks and wormhole attacks.

Proportional bandwidth allocation with consideration of delay constraint over IEEE 802.11e-based wireless mesh networks

Wireless mesh networks (WMNs) extend the limited transmission coverage of wireless LANs by enabling users to connect to the Internet via a multi-hop relay service provided by wireless mesh routers. In such networks the quality of experience (QoE) depends on both the user location relative to the Internet gateway and the traffic load. Various channel access or queue management schemes have been proposed for achieving throughput fairness among WMN users. However, delay and bandwidth utilization efficiency of such schemes may be unacceptable for real-time applications. Accordingly, the present study proposes a proportional bandwidth allocation scheme with a delay constraint consideration for enhancing the QoE of users of WMNs based on the IEEE 802.11e standard. An analytical model of the proposed scheme is provided. Moreover, the performance of the proposed scheme is systematically compared with that of existing bandwidth allocation methods. The simulation results show that the proposed scheme outperforms previously proposed schemes in terms of both an improved throughput fairness among the WMN users and a smaller end-to-end transmission delay.

Router Node Placement With Service Priority in Wireless Mesh Networks Using Simulated Annealing With Momentum Terms

In wireless mesh networks (WMNs), mesh clients communicate with each other via the gateway and bridging functions of mesh routers. The performance of a WMN is generally affected by its network connectivity and client coverage, both of which are determined by its router node placement (RNP) in the deployment area. For simplicity, previous works considered only the RNP where each mesh client is served as an equal. In practice, however, mesh clients should be served with different priorities owing to factors such as their importance and their different payments for the service access. To fulfil this requirement, by assuming that each mesh client is also associated with a service priority, this paper investigates an RNP problem with a service priority constraint in which the mesh clients with service priorities higher than a threshold must be served. Given that this problem inherited from the complexity of the original RNP problem is computationally intractable in general, this paper also develops a novel simulated annealing (SA) approach that takes into account momentum terms to improve the efficiency and accuracy of annealing schedules and prevent fluctuations in values of the acceptance probability function. Additionally, the time complexity of the proposed SA algorithm is analyzed. Furthermore, evaluation of different-size instances under various parameters and annealing schedules demonstrates the superiority of the proposed approach.

Routing Topologies of Wireless Sensor Networks for Health Monitoring of a Cultural Heritage Site.

This paper provides a performance evaluation of tree and mesh routing topologies of wireless sensor networks (WSNs) in a cultural heritage site. The historical site selected was San Juan Bautista church in Talamanca de Jarama (Madrid, Spain). We report the preliminary analysis required to study the effects of heating in this historical location using WSNs to monitor the temperature and humidity conditions during periods of weeks. To test which routing topology was better for this kind of application, the WSNs were first deployed on the upper floor of the CAEND institute in Arganda del Rey simulating the church deployment, but in the former scenario there was no direct line of sight between the WSN elements. Two parameters were selected to evaluate the performance of the routing topologies of WSNs: the percentage of received messages and the lifetime of the wireless sensor network. To analyze in more detail which topology gave the best performance, other communication parameters were also measured. The tree topology used was the collection tree protocol and the mesh topology was the XMESH provided by MEMSIC (Andover, MA, USA). For the scenarios presented in this paper, it can be concluded that the tree topology lost fewer messages than the mesh topology.

Pre-scheduled handoff for service-aware and seamless internet access

Existing handoff techniques connect a user to a nearby access point whenever it is available along the user’s moving path. If the path is not fully Wi-Fi covered, the user may suffer from frequent disconnections. In this work, we propose a pre-scheduled handoff scheme, which determines a quality-aware path so a mobile user can move across an Urban Wi-Fi Mesh network with uninterrupted Internet access at a required data rate. This scheme has several novel techniques. Firstly, by concurrently considering the received signal strength at mobile users and the load of mesh routers (MRs), we design two path finding metrics, contact weight and handoff count, according to the coverage information. Secondly, to measure the path metric in a practical mesh network with irregular and dynamic MR coverage, we propose a light-weight Bloom-filter-based polling algorithm to discover the mobile stations (called STAs) covered in MR, and a Bloom-filter-based probabilistic algorithm to estimate the degree of coverage overlapping among MRs. Thirdly, based on the path metrics, our proposed scheme supports flexible rate requirements from mobile users through a fully distributed multi-service-class path finding algorithm. Our pre-scheduled scheme considers both mobility and connection requirement, so that the mobile user can continuously access the Internet with the expected data rate. To our best knowledge, this is the first work to ensure seamless Internet access with rate consideration by finding a Wi-Fi covered geographic path in a practical wireless mesh network. We have carried out extensive simulations, and the simulation results show that the pre-scheduled handoff scheme can provide appealing high data rate to mobile user with minimum handoff delay.

A Cross-Layer Framework for Joint Routing and Resource Management in Multi-radio Infrastructure Wireless Mesh Networks

In this paper, we propose a cross-layer framework for joint routing and resource management for multi-radio infrastructure wireless mesh networks (WMNs). WMNs are emerging as promising wireless backhaul technology to connect various types of networks to the Internet. Multi-Channel Multiple-Radio capabilities of mesh routers in WMNs achieve high performance but introduce interference and can degrade QoS. Thus, the design of cross-layer routing metrics to improve the QoS has become an important research issue. The routing metrics proposed in the literature do not estimate the delay and interference collectively and accurately and lack the analytical model in their design. Thus, we design new routing metric called interference and delay-aware (IDA) metric based on analytical model. IDA estimates the delay using contention as well as transmission delay and inter-flow interference using the combination of logical and physical model. Furthermore, routing protocols use the per-flow-based scheduling mechanism for interface scheduling which incur a delay for multimedia traffic. Toward this, we propose a cross-layer framework by performing per-packet-based scheduling of multiple interfaces using the statistics collected by IDA metric. We implement cross-layer framework in Optimized Link State Routing Protocol using NS2. The results reveal that IDA routing metric performs better in terms of throughput and delay compared to interference-aware routing (iAWARE), contention-aware transmission time (CATT) and metric for interference and channel diversity (MIND). In addition, IDA-based framework for joint routing and interface scheduling provides delay guarantees compared to CATT-based framework reported in the literature.

Evaluating Impact of Wormhole on Distance Error and Connectivity of Network

mesh networks are the emerging wireless networks which are self organizing, maintaining, healing and configuring. The main trait of WMN is its dynamic and multi- hop nature. These networks provide the internet services to its users on low costs and with high bandwidth. These are made up of mesh routers and mesh clients. They can be easily deployed and are highly scalable. But the security of WMNs is the area of concern due to their vulnerable features they are open to many attacks of which wormhole attack is the worst. A wormhole attack is the one in which two or more conspired nodes forms a tunnel between them via which they sends the network traffic to one another and replays it. In our paper, we study the wormhole attack and then find its impact on distance error and connectivity of nodes. The distance error is found by knowing the ratio of trusted links and that of connectivity is found by knowing the unaffected, disconnected and partially affected nodes.

A Wireless Sensor Network for Feedlot Animal Health Monitoring

Cattle health monitoring on the feedlot is a crucial but nontrivial task. The conventional way of monitoring relies heavily on the cowboy’s visual surveillance, which makes the animal monitoring quality highly subjective and correlated with the obviousness of the observed traits. In order to achieve early detection of each individual animal’s illness, in this paper, a wireless sensor network system is developed to monitor the animal’s feeding and drinking behaviors. A directional antenna is used to allow one router to monitor multiple animals simultaneously, and an energy efficient mesh routing strategy is proposed to aggregate the monitoring data. The performance of the proposed system has been evaluated through numerical analysis and simulations. The contributions of this paper lie in the novelty and feasibility of using directional antenna and wireless sensor network technologies for feedlot animal health monitoring.

PRIDE: A practical intrusion detection system for resource constrained wireless mesh networks

As interest in wireless mesh networks grows, security challenges, e.g., intrusion detection, become of paramount importance. Traditional solutions for intrusion detection assign full IDS responsibilities to a few selected nodes. Recent results, however, have shown that a mesh router cannot reliably perform full IDS functions because of limited resources (i.e., processing power and memory). Cooperative IDS solutions, targeting resource constrained wireless networks, impose high communication overhead and detection latency. To address these challenges, we propose PRIDE (Practical Intrusion Detection system for resource constrained wireless mesh networks), a non-cooperative real-time intrusion detection scheme that optimally distributes IDS functions to nodes along traffic paths, such that intrusion detection rate is maximized, while resource consumption is below a given threshold. We formulate the optimal IDS function distribution as an integer linear program and propose algorithms for solving it effectively and fast (i.e., practical). We evaluate the performance of our proposed solution in a real-world, department-wide, mesh network. An earlier version of this article appeared in ICICS 2013 (Hassanzadeh et al., 2013) and the current article is significantly extended with new technical contents.

LBMR: Load-Balanced Multipath Routing for Wireless Data-Intensive Transmission in Real-Time Medical Monitoring.

In wireless networks, low-power Zigbee is an excellent network solution for wireless medical monitoring systems. Medical monitoring generally involves transmission of a large amount of data and easily causes bottleneck problems. Although Zigbee’s AODV mesh routing provides extensible multi-hop data transmission to extend network coverage, it originally does not, and needs to support some form of load balancing mechanism to avoid bottlenecks. To guarantee a more reliable multi-hop data transmission for life-critical medical applications, we have developed a multipath solution, called Load-Balanced Multipath Routing (LBMR) to replace Zigbee’s routing mechanism. LBMR consists of three main parts: Layer Routing Construction (LRC), a Load Estimation Algorithm (LEA), and a Route Maintenance (RM) mechanism. LRC assigns nodes into different layers based on the node’s distance to the medical data gateway. Nodes can have multiple next-hops delivering medical data toward the gateway. All neighboring layer-nodes exchange flow information containing current load, which is the used by the LEA to estimate future load of next-hops to the gateway. With LBMR, nodes can choose the neighbors with the least load as the next-hops and thus can achieve load balancing and avoid bottlenecks. Furthermore, RM can detect route failures in real-time and perform route redirection to ensure routing robustness. Since LRC and LEA prevent bottlenecks while RM ensures routing fault tolerance, LBMR provides a highly reliable routing service for medical monitoring. To evaluate these accomplishments, we compare LBMR with Zigbee’s AODV and another multipath protocol, AOMDV. The simulation results demonstrate LBMR achieves better load balancing, less unreachable nodes, and better packet delivery ratio than either AODV or AOMDV.

Adaptive router node placement with gateway positions and QoS constraints in dynamic wireless mesh networks

Conventionally, router node placement is concerned with placing only routers to serve clients; and gateway placement is concerned with placing only gateways to achieve some requirements for routers. More generally, this work considers the placement with routers and gateways simultaneously, while clients can move based on their own willingness. That is, this work investigates the adaptive placement problem of a dynamic wireless mesh network (dynWMN) consisting of mesh clients, mesh routers, and Internet gateways. Given fixed positions of Internet gateways, this problem is to adjust positions of mesh routers dynamically to make each mesh client connected with some gateway via multi-hop communication at different times, when each mesh client may switch on or off network access, so that both network connectivity and client coverage are maximized, subject to the Quality of Service (QoS) constraints of delay hops, relay load, and gateway capacity. To avoid almost-overlapping routers and few-clients-covered routers in router node placement, this work further proposes a novel particle swarm optimization approach with three local search operators. In simulation of dynWMNs, dynamics of mesh clients can be characterized by a Markov chain, and hence, their stable states can be derived theoretically and are used as criteria of evaluating performance, by which the proposed approach shows promising performance and adaptability to topology changes at different times.

Performance Analysis of Large Multi-Interface Wireless Mesh Networks with Multi-Different Bandwidth Channel

In this paper, we study the asymptotic throughput capacity of a static multi-channel multi-interface infrastructure wireless mesh network (InfWMN) wherein each infrastructure node has m interfaces and c channels of unequal bandwidth are available. First, an upper bound on the InfWMN per-user capacity is established. Then, the feasible lower bound is derived by construction. We prove that both lower and upper bounds are tight. We limit our analysis for more practical case of $\mathrm{m} \le \mathrm{c}$ . However, for the asymptotic upper bound, our analysis can be used for the general case in which there is no constraint on m and c. Our study shows that in such a network with Nc randomly distributed mesh clients, Nr regularly placed mesh routers, and Ng gateways, the asymptotic per-client throughput capacity has different bounds, which depend on the ratio between the total available bandwidth for the network and the sum of m first greatest data rates of c available channels, i.e., $\sum \limits_{\mathrm{j} = 1}^\mathrm{C} \mathrm{w}_\mathrm{j} / \sum \limits_{\mathrm{j} = 1}^\mathrm{m} \mathrm{w}_\mathrm{j}$ . The results of this paper are more general compared to the existing published researches. In addition, in the case that $\mathrm{w}_\mathrm{i} = \mathrm{W}/\mathrm{c} \forall \mathrm{i},\mathrm{}1 \le \mathrm{i} \le \mathrm{c}$ , our results reduce to the previously reported studies. This implies that our study is comprehensive compared to the formerly published researches.

On Demand Stable Routing with Channel Allocation and Backoff Countdown Optimization in Wireless Mesh Networks

The multi-channel and multi-interface wireless mesh networks (WMNs) allow multiple orthogonal channels simultaneously to facilitate increased broadband connectivity to the end-users. Many efforts have been devoted to allocate the channels to the interfaces in a multi-channel multi-interface setting. Recently, the hybrid channel allocation mechanism jointly optimizes the routing and channel assignment, by utilizing the queuing traffic. It is essential to map the optimization of traffic distribution on each channel along with channel switching in such an order that it adapts to the changing traffic. However, the contention in medium access and channel switching delay are the key issues in a multi-channel hidden terminal problem. The proposed optimized stable path- channel allocation and routing (OSCAR) protocol is a hybrid multi-channel protocol that reduces the communication delay without degrading the network performance. The proposed work, OSCAR determines a highly stable path that increases mesh routers to improve the routing efficiency. The channel allocation mechanism mainly promotes queue dynamics based probabilistic channel selection (QDPCS), and backoff countdown optimization (BCO). An essential component of the QDPCS scheme is the factor of queuing utilization, and this strategy selects a least congested channel. The BCO mechanism creates the logical order among contending nodes based on the remaining backoff value. It reduces the medium access delay and enables the feasibility of scheduled transmissions without degrading the network throughput. Finally, the performance evaluation results show that the OSCAR protocol outperforms the existing protocol over WMNs.

A cross-layer optimization for delay-aware load balancing in multi-radio wireless mesh networks

In this paper, we propose a cross-layer optimization technique for multi-radio Wireless Mesh Networks (WMNs) using new routing metric and load balancing mechanism. WMNs are an emerging technology and are used as a backhaul network to connect various types of networks to the internet. These networks consist of mesh routers with multi-radio support to enhance the capacity. As the traffic density is very high from the client mesh to the gateways, load balancing in these networks has become an important research issue. For this, multipath routing which can exploit the multi-radio capabilities to balance the traffic simultaneously through mesh routers is required. To address this, we analytically derive the routing metric using IEEE 802.11 Distributed Coordination Function (DCF) delay model. Using this model, we propose a routing metric called Passive Interference and Delay Aware (PIDA) metric for multipath routing to find the interference free paths. We extend the work by performing load balancing on multiple paths as well as on multiple interfaces using the proposed metric. We implement our techniques using popular Ad hoc On-demand Multipath Distance Vector (AOMDV) routing protocol in NS2. The results reveal that PIDA performs better in terms of throughput and average delay compared to recently proposed routing metrics with minimal routing overhead. In addition, load balancing mechanism with PIDA metric shows better results depending on the congestion level in the network.

A cross-layer framework for joint routing and rate adaptation in infrastructure Wireless Mesh Networks

In this paper, we propose a cross-layer framework for joint routing and rate adaptation in multi-rate, Multi-Channel, Multi-Radio (MCMR) infrastructure Wireless Mesh Networks (WMNs). These networks use MCMR capabilities of mesh routers to achieve high performance. However, the MCMR nodes introduce interference in the multi-hop mesh networks and can degrade QoS. Thus, the design of routing metrics to improve the QoS has become an important research issue. Furthermore, as the routing metric and rate adaptation decisions are closely related, the joint approach is needed to improve the performance of the network. Towards this, we analytically derive our routing metric using IEEE 802.11 Distributed Coordination Function (DCF) basic access mechanism. Using this model, we propose Passive Interference and Delay Aware (P-IDA) routing metric which estimates the delay and interference by exploiting cross-layer information. We extend the work by performing joint routing and rate adaptation. The simulation results using NS2 reveal that proposed framework improves throughput and delay compared to existing approaches with reduced routing overhead.

Source-Based Routing in Wireless Mesh Networks

Wireless mesh networks (WMNs) are currently used to provide broadband access to the Internet anytime and anywhere. Generally, WMNs consist of mesh routers equipped with one or more interfaces allowing connectivity to the Internet through gateways. To route traffic from sources to destinations, many routing protocols have been proposed in the literature. However, most of them take into account at most one metric (e.g., interferences, packet losses, and load at gateways). Moreover, almost all of these schemes consider only one type of interferences: interflow or intraflow. In this paper, we propose a new source routing and gateway selection scheme, which is called source-based routing (SBR), that improves the performance of WMNs. SBR uses a novel routing metric, which is a combination of packet losses, intraflow and interflow interferences, and load at gateways, to select best paths to reach selected gateways. Simulation results show that the proposed SBR improves the network performance and outperforms existing routing schemes, which are based on expected transmission count (ETX), nearest gateway (NG; i.e., shortest path to gateway), load at gateways (LG), or interference ratio (IR); more specifically, SBR yields 33%, 26%, 13%, and 10% more throughput compared with LG, ETX, NG, and IR, respectively.

PASER: Secure and Efficient Routing Approach for Airborne Mesh Networks

Low-altitude unmanned aerial vehicles (UAVs) combined with WLAN mesh networks (WMNs) have facilitated the emergence of airborne network-assisted applications. In disaster relief, they are key solutions for 1) on-demand ubiquitous network access and 2) efficient exploration of sized areas. Nevertheless, these solutions still face major security challenges as WMNs are prone to routing attacks. Consequently, the network can be sabotaged, and the attacker might manipulate payload data or even hijack the UAVs. Contemporary security standards, such as the IEEE 802.11i and the security mechanisms of the IEEE 802.11s mesh standard, are vulnerable to routing attacks as we experimentally showed in previous works. Therefore, a secure routing protocol is indispensable for making feasible the deployment of UAV-WMN. As far as we know, none of the existing research approaches have gained acceptance in practice due to their high overhead or strong assumptions. Here, we present the position-aware, secure, and efficient mesh routing approach (PASER). Our proposal prevents more attacks than the IEEE 802.11s/i security mechanisms and the well-known, secure routing protocol ARAN, without making restrictive assumptions. In realistic UAV-WMN scenarios, PASER achieves similar performance results as the well-established, nonsecure routing protocol HWMP combined with the IEEE 802.11s security mechanisms.

An Efficient Mac Protocol for Reducing Channel Interference and Access Delay in Cognitive Radio Wireless Mesh Networks

With the increase of wireless mesh networks, channel access, bandwidth usage and channel interferences are the major key issues of multi-channel WMNs and MAC specifications. The multi-radio, multi-channel wireless mesh networks (MR-MC-WMNs) are a kind of networks that provide high reliable communication for a large number of mesh nodes. These networks have mesh routers and channels that are stationary and each router or node has multiple channels. Although IEEE 802.11 versions support up to 3 and 12 multiple non-overlapping channels, it is the major challenge of the multichannel environment which exploits all channels to communicate a large volume of network data in WMNs. Cognitive radio users has the capability to access unused portion of the multichannel spectrum. The major interference can be created by CR as well as licensed user. Traditional MAC based operations are implemented using common-control-channel to handle cognitive radio end users. We proposed a new Multi-objective based CMR-MC-WMNs framework using TDMA based MAC protocol to optimize the network performance, channel interference and access delay issues in the network. Experimental results prove that, proposed work has less delay and inference rates compared to traditional models.