Infrastructure Wireless Mesh Networks Research Articles

User Centric Cache Allocation Schemes in Infrastructure Wireless Mesh Networks

User Centric Cache Allocation Schemes in Infrastructure Wireless Mesh Networks

A cross-layer interference and delay-aware routing metric for multi-radio infrastructure wireless mesh networks

In this paper, we propose new cross-layer interference and delay aware (CL-IDA) routing metric for multi-radio infrastructure wireless mesh networks (WMNs). WMNs use multichannel multiple radio (MCMR) capabilities of mesh routers to achieve high performance. However, QoS degrades significantly due to inter-flow and intra-flow interference as the number of hops and radio interfaces increase. Thus, design of routing protocols combined with routing metrics to improve QoS has become an important research issue. The routing metrics proposed in the literature have their own disadvantages and lack the analytical model in their design. Towards this, we design and implement CL-IDA metric based on the analytical model by estimating delay, inter-flow and intra-flow interference using cross-layer information. We implement this metric using optimised link state routing (OLSR) protocol in NS2. The results reveal that, CL-IDA metric performs better in terms of throughput and average delay compared to well known routing metrics.

A Network Resource Management Framework for Wireless Mesh Networks

In infrastructure wireless mesh networks (WMNs), a mobile station (STA) associates with one of the nearby mesh access points (MAPs) that are connected to a capacity-limited wireless multi-hop backhaul. For better network resource utilization in WMNs, it is preferred that more traffic is carried by the good-backhaul MAPs that are closer to the portal or having better backhaul condition. In this paper, by taking the features of WMNs and the inter-cell interference into consideration, we propose a network resource management framework that jointly manages MAP–STA association, MAP access network channel assignment, and user bandwidth allocation. The proposed framework is composed of three components: an optimization-based association control algorithm that improves the network resource utilization by associating more STAs with the good-backhaul MAPs, an access network channel assignment algorithm that effectively increases the network capacity by reducing the interference at the good-backhaul MAPs, and a utility-fair bandwidth allocation algorithm that is flexible in adjusting the trade-off between network throughput and user fairness. We demonstrate the superior performance of the proposed algorithms through simulations with various network topologies and conditions.

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.

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.

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.

A fuzzy logic-based sustainable and trusted routing for P2P enabled smart grid

Smart grid is the trend of next generation electrical power system which has integrated the information and communication technologies and enables the existing power grid to perform more intelligent and efficient operations. A high level of network availability is therefore required to guarantee two-way flows of electricity and information among electrical units. The peer-to-peer wireless mesh network infrastructure can provide redundant routes for the smart grid communications to ensure the network availability. However, the P2P infrastructure is vulnerable to cyber-attacks. In this paper, we propose a new fuzzy-based energy aware trusted geo-routing FEATGR, which can decide the optimal end-to-end path between any source and destination by effectively leveraging the energy consumption, location and trust metrics. The extensive simulation studies have confirmed that FEATGR is capable to achieve the stable and secured routing performance and also can guarantee the high level of network availability for P2P smart grid communications.

A Cross-Layer Interference and Delay-aware Routing Metric for Infrastructure Wireless Mesh Networks

A Cross-Layer Interference and Delay-aware Routing Metric for Infrastructure Wireless Mesh Networks

Energy Optimized Routing Algorithm for Hybrid Wireless Mesh Networks in Coal Mine

Mesh clients in hybrid wireless mesh networks can participate in networking and routing. When the backbone transmission network is broken, the mesh client can route and forward the data, which will eliminate the absolute dependence on the backbone network of traditional infrastructure wireless mesh networks in mine emergency rescue. However, the energy of mesh clients is limited. Based on the comprehensive consideration of the efficiency and balance of energy consumption of mesh clients for data transmission, a new energy cost criterion is designed. Energy optimized and fault recovered routing algorithm is proposed on account of different network states. At last, the simulation analysis on the performance of routing algorithm is conducted and compared with typical routing algorithms. Simulation results show that the algorithm has effectively extended the network lifetime and achieved optimized combination of energy efficiency and energy balance. When mesh routers in the backbone network are failed, this algorithm can rapidly rebuild the route and shows strong capacity of routing recovery.

Trust-based Adaptive Routing for Smart Grid Systems

Smart Grid is the trend of next generation electrical power system which makes the power grid intelligent and energy efficient. It requires high level of network reliability to support the two-way communication among electrical services, electrical units such as smart meters, and applications. The wireless mesh network infrastructure can provide redundant routes for the Smart Grid communication network to ensure the network availability. Also due to its high level of flexibility and scalability features that make it become a promising solution for Smart Grid. However, similar with many other distributed ad-hoc networks, trust is a critical issue for wireless mesh networks. In this paper, we proposed a novel trust-based geographical routing protocol, named as Dynamic Trust Elective Geo Routing (DTEGR), which allows peers in a Smart Grid system to adjust their interaction behaviors based on the trustworthiness of others. The simulation studies have confirmed that DTEGR can achieve better routing performance in different network scenarios, and also to achieve high level of reliable data transmission in Smart Grid communication networks.

Channel Assignment for Throughput Optimization in Multichannel Multiradio Wireless Mesh Networks Using Network Coding

Compared to single-hop networks such as WiFi, multihop infrastructure wireless mesh networks (WMNs) can potentially embrace the broadcast benefits of a wireless medium in a more flexible manner. Rather than being point-to-point, links in the WMNs may originate from a single node and reach more than one other node. Nodes located farther than a one-hop distance and overhearing such transmissions may opportunistically help relay packets for previous hops. This phenomenon is called opportunistic overhearing/listening. With multiple radios, a node can also improve its capacity by transmitting over multiple radios simultaneously using orthogonal channels. Capitalizing on these potential advantages requires effective routing and efficient mapping of channels to radios (channel assignment (CA)). While efficient channel assignment can greatly reduce interference from nearby transmitters, effective routing can potentially relieve congestion on paths to the infrastructure. Routing, however, requires that only packets pertaining to a particular connection be routed on a predetermined route. Random network coding (RNC) breaks this constraint by allowing nodes to randomly mix packets overheard so far before forwarding. A relay node thus only needs to know how many packets, and not which packets, it should send. We mathematically formulate the joint problem of random network coding, channel assignment, and broadcast link scheduling, taking into account opportunistic overhearing, the interference constraints, the coding constraints, the number of orthogonal channels, the number of radios per node, and fairness among unicast connections. Based on this formulation, we develop a suboptimal, auction-based solution for overall network throughput optimization. Performance evaluation results show that our algorithm can effectively exploit multiple radios and channels and can cope with fairness issues arising from auctions. Our algorithm also shows promising gains over traditional routing solutions in which various channel assignment strategies are used.

Throughput capacity analysis of large multi-channel, multi-interface random wireless mesh networks

This paper studies the asymptotic throughput capacity of a random infrastructure wireless mesh network (RndInfWMN). Generally an infrastructure wireless mesh network (InfWMN) comprises mesh clients, routers, gateways and has hierarchical structures. An InfWMN can be divided into two categories, which are arbitrary InfWMN (ArbInfWMN) and random InfWMN (RndInfWMN). In an ArbInfWMN, the locations of the WMRs are arbitrary while in an RndInfWMN, WMRs are distributed randomly. The latter is more interesting when randomly distributed WLANs are desired to be connected through a wired network of gateways. There are some analytical research on the asymptotic capacity of ArbInfWMN where the number of interfaces per-infrastructure node, m, is at the same order of the number of available channels for the network, c, i.e. cm=θ(1). In our previous research, we investigated the asymptotic throughput capacity of ArbInfWMNs for a more general case in which cm=O(1). However, to date, analytical facility has been limited by the absence of analysis in RndInfWMNs, especially for the general case in which cm=O(1). In this paper, we carry out an original analysis of the asymptotic per-client throughput capacity of multi-channel multi-interface RndInfWMNs for the case in which cm=O(1). Our analysis shows that by identifying cm in different scaling regimes, the asymptotic per-client throughput capacity of multi-channel multi-interface RndInfWMNs exhibits different bounds, depending on the ratio between c and m.

IMeX: Intergateway Cross-Layer Handoffs in Internet-Based Infrastructure Wireless Mesh Networks

Wireless mesh networks (WMNs) have recently emerged to be a cost-effective solution to support large-scale wireless Internet access. Handoff management plays an important role in WMNs in delivering Quality of Service to mobile users. In this paper, the handoff support in Internet-based infrastructure WMNs is investigated. Previous solutions on handoff management in infrastructure WMNs mainly focus on intragateway mobility (e.g., single gateway is assumed in IEEE 802.11s WMNs). Furthermore, new handoff issues involved in intergateway mobility in WMNs (e.g., the network-layer handoff detection issue) have not been properly addressed. In this paper, a new architectural design, IMeX, is proposed to facilitate intergateway handoff management in Internet-based infrastructure WMNs. The proposed IMeX architecture is designed to specifically address the special handoff challenge in Internet-based WMNs. It can facilitate parallel executions of handoffs from multilayers, in conjunction with a data caching mechanism which guarantees minimum packet loss during handoffs. The required number and optimal placement of special mesh routers that form the IMeX architecture are modeled as a set covering problem which is solved based on a greedy algorithm. A comprehensive simulation study shows that the IMeX architecture enables fast handoffs and reestablishment of session communications in the intergateway mobility environment. Performance results demonstrate that the proposed IMeX architecture, with both the parallel handoff execution and data caching mechanism, outperforms the conventional WMN handoff schemes in terms of reducing handoff delays caused in multilayers and improving end-to-end performance of applications in WMNs.

Optimising multi-rate link scheduling for wireless mesh networks

Traffic in an infrastructure wireless mesh network is routed over multiple hops between clients and gateways, hence performance can be significantly reduced where links interfere with each other. In this paper we consider the problem of optimising link scheduling for wireless mesh networks, making a number of contributions. Adopting a protocol-based model, we introduce an integer programming approach for an optimised schedule using a time-slot model. This model compares favourably against previously published methods and we introduce a rapid heuristic approximation that can present near-optimal solutions in a fraction of the time. We show that taking into consideration the affect of varying data rates across individual links during different time slots can further enhance the throughput achieved. This decreases the local data rate on some links but concurrently reduces the interference range of the transmitted signal which increases spatial reuse across the network. We present efficient heuristics to rapidly find near-optimal solutions to an integer programming model of this problem and provide rigorous justification on benchmark problems.

Asymptotic Throughput Capacity Analysis of Multi-Channel, Multi-Interface Wireless Mesh Networks

Research into the analytical solutions for the capacity of the infrastructure wireless mesh networks (InfWMN) is highly interesting. An InfWMN is a hierarchical network consisting of mesh clients, mesh routers and gateways. The mesh routers form a wireless mesh infrastructure to which the mesh clients are connected through the use of star topology. The previous analytical solutions have only investigated the asymptotic per-client throughput capacity of either single-channel InfWMNs or multi-channel InfWMNs under conditions in which each infrastructure node (i.e. wireless routers and gateways), has a dedicated interface per-channel. The results of previous analytical studies show that there are quite few studies that have addressed the more practical cases where the number of interfaces per-node is less than the number of channels. In this paper, we derive an original analysis of the asymptotic per-client throughput capacity of multi-channel InfWMNs in which the number of interfaces per-infrastructure node, denoted by m, is less than or equal to the number of channels, denoted by c. Our analysis reveals that the asymptotic per-client throughput capacity of multi-channel InfWMNs has different bounds, which depend on the ratio between c and m. In addition, in the case that m < c, there is a reduction in the capacity of the InfWMN compared to the case in which c = m. Our analytical solutions also prove that when \({\frac{\text{c}}{\text{m}}=\Omega\left({\frac{{\rm N}_g^2}{{\rm N}_{\rm r}}}\right)}\), where Ng and Nr denote the number of gateways and mesh routers respectively, gateways cannot effectively increase the throughput capacity of the multi-channel InfWMNs.

OPNET-based modeling and simulation study on handoffs in Internet-based infrastructure wireless mesh networks

Wireless mesh networks (WMNs) have recently emerged to be a cost-effective solution to support large-scale wireless Internet access. Handoff management plays an important role in WMNs in delivering Quality of Service to mobile users. Hence, the analysis of handoff performance in WMNs is in a critical need for network researchers and engineers. Recently, OPNET simulation platform becomes a leading provider of solutions for evaluating network designs and applications. However, there is no formal approach or methodology as to how OPNET can be used to assess the support and readiness of an Internet-based WMN in supporting handoffs incurred by various roaming types. In this paper, we propose detailed simulation models for network topology and elements necessary to construct an Internet-based infrastructure WMN using OPNET, along with the modeling and implementation of two handoff designs considering the special design challenges in WMNs. Sequential handoff steps involved in multilayer handoffs are analyzed thoroughly via the OPNET debug tool. Moreover, the paper discusses many design and engineering issues pertaining to the deployment of handoff management in Internet-based infrastructure WMNs. The implemented simulation module provides handoff performance results for both intra- and inter-gateway roaming scenarios and can be an effective evaluation tool for handoff management designs in Internet-based infrastructure WMNs.

Route Maintenance in IEEE 802.11 wireless mesh networks

In this paper, we propose a novel Route Maintenance scheme for IEEE 802.11 wireless mesh networks. Despite lack of mobility and energy constraints, reactive routing protocols such as AODV and DSR suffer from frequent route breakages in 802.11 based infrastructure wireless mesh networks. In these networks, if any intermediate node fails to successfully transmit a packet to the next hop node after a certain number of retransmissions, the link layer reports a transmission problem to the network layer. Reactive routing protocols systematically consider this as a link breakage (and therefore a route breakage). Transmission failures can be caused by a number of factors e.g. interference or noise and can be transient in nature. Frequent route breakages result in significant performance degradation. The proposed mechanism considers multiple factors to differentiate between links with transient transmission problems from those links which have permanent transmission problems and takes a coherent decision on link breakage. The proposed mechanism is implemented in AODV for single-radio single-channel mesh network and an extension is incorporated in multi-radio multi-channel scenarios. Simulation results show substantial performance improvement compared to classical AODV and local route repair schemes.

On the design of reliable wireless mesh network infrastructure with QoS constraints

In the design of Wireless Mesh Networks (WMNs), one of the fundamental considerations is the reliability and availability of communication paths between network pairs in the presence of node failures. Reliability and deployment cost are important and are largely determined by network topology. In fact, adding redundant network components increases the reliability of a network, but also increases the cost substantially. Usually, network performance and reliability are considered separately. In this paper, we propose a new algorithm based on ear decomposition for constructing reliable WMN infrastructure that resists the failure of a single mesh node and ensures full coverage to all Mesh Clients (MCs). Via a case study, we show the tight relationship between network deployment cost, performance and reliability in a simultaneous optimization in terms of cost and traffic load balancing over network channels. The proposed multi-objective optimization model is solved using meta-heuristics which provides the network operator with a set of reliable tradeoff solutions.

2D MIMO Network Coding with Inter-Route Interference Cancellation

Infrastructure wireless mesh network has been attracting much attention due to the wide range of its application such as public wireless access, sensor network, etc. In recent years, researchers have shown that significant network throughput gain can be achieved by employing network coding in a wireless environment. For further improvement of network throughput in one dimensional (1D) topology, Ono et al. proposed to use multiple antenna technique combined with network coding. In this paper, being inspired by MIMO network coding in 1D topology, the authors establish a novel MIMO network coding algorithm for a 2D topology consisting of two crossing routes. In this algorithm, multiple network coded flows are spatially multiplexed. Owing to the efficient usage of radio resource of network coding and co-channel interference cancellation ability of MIMO, the proposed algorithm shows an 8-fold gain in network capacity compared to conventional methods in the best-case scenario.

Asymptotic Capacity of Infrastructure Wireless Mesh Networks

An infrastructure wireless mesh network (WMN) is a hierarchical network consisting of mesh clients, mesh routers and gateways. Mesh routers constitute a wireless mesh backbone, to which mesh clients are connected as a star topology, and gateways are chosen among mesh routers providing Internet access. In this paper, the throughput capacity of infrastructure WMNs is studied. For such a network with Nc randomly distributed mesh clients, Nr regularly placed mesh routers and Ng gateways, assuming that each mesh router can transmit at W bits/s, the per-client throughput capacity has been derived as a function of Nc , Nr , Ng and W . The result illustrates that, in order to achieve high capacity performance, the number of mesh routers and the number of gateways must be properly chosen. It also reveals that an infrastructure WMN can achieve the same asymptotic throughput capacity as that of a hybrid ad hoc network by choosing only a small number of mesh routers as gateways. This property makes WMNs a very promising solution for future wireless networking.