Wireless Mesh Network Research Papers (original) (raw)

Advances in wireless personal area networks have made the practical deployment of various services possible, which until a few years ago was considered extremely costly or labor intensive. We build such a wireless sensor network for precision agriculture where real time data of the climatological and other environmental properties are sensed and relayed to a central repository. The architecture comprises of three distinct sections-(a) the sensor-nodes (b) the wireless mesh network and (c) the actuation components. The sensors are selected based on the properties suited for the most common crops and we identify four such attributes. The sensor network is based on the IEEE-802.15.4 standard and we develop a new static routing algorithm suited for the sensing application. The algorithm overrides the deficiency of the Hierarchical Routing scheme inherent in the ZigBee specification where the C skip addressing algorithm limits the possible depth of the network topology due to address wastage. The new algorithm maintains the hierarchical network topology and thus ensures routing at its optimal best. The algorithms for both addressing and routing are provided. The actuation components are also a part of mesh network and are activated wirelessly for controlling irrigation and fertigation.

- by
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- Precision Agriculture, Routing, Wireless Sensor Networks, Agriculture

We focus on a setting where users of a real-time networked application need to be assigned to servers, e.g., assignment of hosts to Internet gateways in a wireless mesh network (WMN). The service delay experienced by a user is a sum of the network-incurred delay, which depends on its network distance from the server, and a server-incurred delay, stemming from the load on the server. We introduce the problem of load-distance balancing, which seeks to minimize the maximum service delay among all users. We address the challenge of finding a near-optimal assignment in a distributed manner, without global communication, in a large network. We present a scalable algorithm for doing so, and evaluate our solution with a case study of its application in an urban WMN.

- by Israel Cidon
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- Case Study, Real Time, Wireless Mesh Network

The growth of multimedia applications and wireless systems requires a new behavior of routing protocols for Wireless Mesh Networks (WMNs). It is necessary to provide not only the minimum requirements for Quality of Service (QoS), but also to assure the Quality of Experience (QoE) support for multimedia applications. In this context, the usage of only one link quality metric for routing different types of packets within the network is not enough to ensure applications with suitable QoS and QoE levels. This paper presents a variation of the WMN routing protocol Optimized Link State Routing (OLSR), to achieve QoS and QoE requirements for multimedia applications. It is based on the dynamic choice of metrics and in a Fuzzy Link Cost (FLC) to determine the best routes for multimedia packets. The proposed FLC metric is based on a fuzzy system that uses two link quality metrics, namely Expected Transmission Count (ETX) and Minimum Delay (MD), to define a new metric. Simulations were performed to demonstrate the performance of the proposed metric compared to the ones present in the original OLSR and other current versions of this protocol. For comparison purposes, it was considered different performance evaluation QoS metrics and the quality of videos received by the user in a higher competition scenario.

- by Rafael Gomes
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- Wireless Systems, Network, Quality of Experience, Performance Evaluation

In this paper, we focus on broadband wireless mesh networks like 3GPP LTE-Advanced. This technology is a key enabler for next generation cellular networks which are about to increase by an order of magnitude the capacity provided to users. Such an objective needs a significative densification of cells which requires an efficient backhauling infrastructure. In many urban areas as well as under-developed countries, wireless mesh networking is the only available solution. Besides, economical and environmental concerns require that the energy expenditure of such infrastructure is optimized.

- by anis ouni
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- Linear Programming, Routing, Wireless Mesh Networks, Energy Consumption

From the network operator's point of view, the high CAPEX/OPEX cost resulting from fixed/wired backhaul links can be inhibitive to successful deployment of broadband wireless services. The emerging wireless mesh network (WMN) technology is seen as one of the potential solutions which may reduce wired backhaul dependency through multihop transmission. Despite the advantages, many remain sceptical on WMN's network capacity and scalability performances particularly when the user density is high. This paper provides an insight on the best possible upper-bound capacity performance of WMN, taking into consideration three key design parameters namely 1) Percentage of wired backhaul points per network, 2) Mesh-to-Access Link-Rate Ratio (R) and 3) Number of radio interfaces per mesh node including hybrid radio options. These design options are compared and contrasted with different deployment densities. The results generally show that the higher the number of backhaul points, the higher the effective access capacity available to mesh node and hence user domain. Increasing the R and the number of radio per mesh node are two alternative means to push up the effective access capacity per mesh node without increasing the number of wired backhaul points. This is most significant in multi radio system where about 80% of the backhaul points can be eliminated with R= 3 in order to maintain effective access capacity close to full rate (Capacity, C=1) per mesh node. It is also found that 50% of the backhaul points can be eliminated with R=2 for all radio options (except for the pure single radio case).

Telemedicine promises an improvement of health care service quality in rural, urban, dense and mobile areas. In order to implement the telemedicine in these areas, a low cost telemedicine system with acceptable quality for medical data transfer is required. This paper discusses simulation and implementation results of a low cost telemedicine system including wireless medical interface and communication infrastructure. A simulation has been done to investigate the network quality of service. The infrastructure has been also implemented using low cost 5.8 GHz transceiver for backhauls and low cost 2.4 GHz transceiver for clients. Test result shows that the low cost telemedicine system is able to do real time communication between patient and medical staff with medical data rate up to 2 Mbps. It shows that the low cost telemedicine system using wireless mesh network can be implemented in remote area with acceptable medical data transfer quality.

- by Eko Pratama Putra
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- Health Care, Service Quality, Quality of Service, Health Care Services

Wireless sensor nodes, each a self-powered system performing sensing, communication, and computation, form reliable mesh networks coordinating efforts to add intelligence to the environment. ABSTRACT | Wireless sensor nodes are autonomous devices incorporating sensing, power, computation, and communication into one system. Applications for large scale networks of these nodes are presented in the context of their impact on the hardware design. The demand for low unit cost and multiyear lifetimes, combined with progress in CMOS and MEMS processing, are driving development of SoC solutions for sensor nodes at the cubic centimeter scale with a minimum number of offchip components. Here, the feasibility of a complete, cubic millimeter scale, single-chip sensor node is explored by examining practical limits on process integration and energetic cost of short-range RF communication. Autonomous cubic millimeter nodes appear within reach, but process complexity and substantial sacrifices in performance involved with a true single-chip solution establish a tradeoff between integration and assembly.

This paper presents a distributed implementation of RAND, a randomized time slot scheduling algorithm, called DRAND. DRAND runs in O(δ) time and message complexity where δ is the maximum size of a two-hop neighborhood in a wireless network while message complexity remains O(δ), assuming that message delays can be bounded by an unknown constant. DRAND is the first fully distributed version of RAND. The algorithm is suitable for a wireless network where most nodes do not move, such as wireless mesh networks and wireless sensor networks. We implement the algorithm in TinyOS and demonstrate its performance in a real testbed of Mica2 nodes. The algorithm does not require any time synchronization and is shown to be effective in adapting to local topology changes without incurring global overhead in the scheduling. Because of these features, it can also be used even for other scheduling problems such as frequency or code scheduling (for FDMA or CDMA) or local identifier assignment for wireless networks where time synchronization is not enforced.

- by Sangeetha .P
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- Distributed Computing, Time Synchronization, Wireless Network, Network Performance
- by Samik Ghosh
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- Distributed Computing, Wireless Mesh Networks, Mobile Communication, Mesh Networks

Wireless mesh network (WMN) has become an important leading technology which provides several types of useful applications such as community network, broadband home network and internet access, etc. The rise in the size of users in WMN has created a degradation of efficiency in a network especially in dense areas due to the clumsy channel allocation and hence creating many challenges for enhancing the users experience, network quality and throughput. Therefore in this paper, we proposed OCA based AIF model that can access the channel information and then it process to improve the RF channel association. The proposed OCA-AIF will function for each period when some interference is detected via AIF and we further extend this analysis by taking in to consideration the influence of interference to provide a high quality indicator in network. The analysis of result shows the optimization by our proposed approach which increases as per the increment of relay nodes (RNs).

This chapter presents IEEE 802.11s, an emerging standard for wireless mesh networks (WMNs). IEEE 802.11s proposes multihop forwarding at the MAC level, which is a new approach for building WMNs. Traditional solutions for WMNs use network-level routing protocols to allow multihop forwarding among wireless mesh nodes. IEEE 802.11s specifies multihop MAC functions for mesh nodes using a mandatory path selection mechanism named HWMP (Hybrid Wireless Mesh Protocol) and also provides a path selection framework for alternative mechanisms and future extensions. This chapter discusses the emerging standard details and compares this new solution for WMNs to traditional ones.

- by Luis Henrique M K Costa
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- Routing Protocol, Wireless Mesh Network, Path Selection
- by Guido Hiertz
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- Distributed Computing, Routing, Wireless Mesh Networks, Wireless

Wireless networks are truly pervasive in the modern environment: from the workplace and the home, to implanted medical devices. Network security, therefore, is of paramount importance. This volume begins with an overview of the security vulnerabilities of wireless sensor networks, but also offers some means of defence against them. It goes on to propose ways of securing routing in wireless mesh networks. Two further chapters offer in-depth studies of secure and privacy-preserving data protocols for wireless sensor and mesh networks. The book concludes with an overview of the history of homomorphism encryption as a means of securing data, also covering some emerging trends in which this form of encryption offers exciting new possibilities.

Mesh networks are multi-hop wireless networks that can be used as a low cost infrastructure for community and city-wide access networks. In this context, support for killer applications such as cooperative services and mobile multimedia applications are in great demand. This mini-course presents the main challenges and solutions for providing mobility, quality of service (QoS) and multicasting in wireless mesh

- by Elisângela Aguiar
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- Quality of Service, Ad hoc network, Wireless Mesh Network, Mobile Multimedia

Wireless mesh networks (WMNs) are two-tier wireless multihop networks. The top tier is made of wireless routers, which provide access to the wireless clients in the bottom tier. One technology for enabling multi-hop communication in the top tier is IEEE 802.16, which includes a mesh mode, in addition to the Point-to-Multipoint mode for cellular networks. As is often the case with wireless networks, simulation is often employed as the primary means of investigation. There are several network simulation tools, both commercial and free-of-charge, with IEEE 802.16 PMP support. However, the MAC protocol designed for mesh mode is substantially different from that for PMP operation, which creates the need for a specific simulation tool. In this paper we describe a simulation module, called WiMsh, than enables simulation of IEEE 802.16 wireless mesh networks with the popular Network Simulator 2. We have made publicly available WiMsh in October 2007 as open source software.

- by Claudio Cicconetti
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- Wireless Mesh Networks, Simulation, Wireless Mesh Network

Wireless mesh networks (WMNs) consist of mesh routers and mesh clients, where mesh routers have minimal mobility and form the backbone of WMNs. They provide network access for both mesh and conventional clients. The integration of WMNs with other networks such as the Internet, cellular, IEEE 802.11, IEEE 802.15, IEEE 802.16, sensor networks, etc., can be accomplished through the gateway and bridging functions in the mesh routers. Mesh clients can be either stationary or mobile, and can form a client mesh network among themselves and with mesh routers. WMNs are anticipated to resolve the limitations and to significantly improve the performance of ad hoc networks, wireless local area networks (WLANs), wireless personal area networks (WPANs), and wireless metropolitan area networks (WMANs). They are undergoing rapid progress and inspiring numerous deployments. WMNs will deliver wireless services for a large variety of applications in personal, local, campus, and metropolitan areas. Despite recent advances in wireless mesh networking, many research challenges remain in all protocol layers. This paper presents a detailed study on recent advances and open research issues in WMNs. System architectures and applications of WMNs are described, followed by discussing the critical factors influencing protocol design. Theoretical network capacity and the state-of-the-art protocols for WMNs are explored with an objective to point out a number of open research issues. Finally, testbeds, industrial practice, and current standard activities related to WMNs are highlighted.

- by Simon Matabva
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- Engineering, Technology, Remote Sensing, Computer Networks

Advances in wireless personal area networks have made the practical deployment of various services possible, which until a few years ago was considered extremely costly or labor intensive. We build such a wireless sensor network for precision agriculture where real time data of the climatological and other environmental properties are sensed and relayed to a central repository. The architecture comprises of three distinct sections -(a) the sensor-nodes (b) the wireless mesh network and (c) the actuation components. The sensors are selected based on the properties suited for the most common crops and we identify four such attributes. The sensor network is based on the IEEE-802.15.4 standard and we develop a new static routing algorithm suited for the sensing application. The algorithm overrides the deficiency of the Hierarchical Routing scheme inherent in the ZigBee specification where the C skip addressing algorithm limits the possible depth of the network topology due to address wastage. The new algorithm maintains the hierarchical network topology and thus ensures routing at its optimal best. The algorithms for both addressing and routing are provided. The actuation components are also a part of mesh network and are activated wirelessly for controlling irrigation and fertigation.

- by Siuli Roy
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- Precision Agriculture, Routing, Wireless Sensor Networks, Agriculture

Mesh networks are multi-hop wireless networks emerging as a low cost infrastructure for community access networks and digital cities. In this context, support for killer applications such as cooperative services and mobile multimedia applications are the in great demand. This mini-course aims at presenting, in a theoretical way, main problems, solutions and challenges for providing security in wireless mesh networks. The course has three main focuses: the mesh networks contextualization; Security issues in wireless mesh networks, with your challenges and deficiency and; the main proposals found in the literature.

- by Elisângela Aguiar
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- Wireless Mesh Network, Mobile Multimedia, MESH NETWORK, Access Network
- by Fabrizio Granelli and +2
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- Distributed Computing, Ubiquitous Computing, Open Source Software, Software Testing

Wireless Mesh Networks (WMNs) have become an important networking infrastructure for providing costefficient broadband wireless connectivity. WMNs are showing their applicability in deployment of medical, transport and surveillance applications in urban areas, metropolitan, neighboring communities and municipal area networks. In this paper, we deal with connectivity and coverage problem of WMN. Because these problems are known to be NP-Hard, we propose and implement a system based on Genetic Algorithms (GAs). We evaluate the performance of the proposed system by different scenarios using different metrics such as client distribution, crossover rate, mutation rate, coverage area and giant component. The simulation results show that for 32 x 32 and 64 x 64 grid area, Linear Ranking is good selection operator and offers the best network connectivity and user coverage.

- by Makoto Takizawa
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- Genetic Algorithms, Wireless Mesh Networks, Distributed System, Genetic Algorithm

Reliable broadband communication is becoming increasingly important during disaster recovery and emergency response operations. In situations where infrastructure-based communication is not available or has been disrupted, an Incident Area Network needs to be dynamically deployed, i.e. a temporary network that provides communication services for efficient crisis management at an incident site. Wireless Mesh Networks (WMNs) are multihop wireless networks with self-healing and self-configuring capabilities. These features, combined with the ability to provide wireless broadband connectivity at a comparably low cost, make WMNs a promising technology for incident management communications. This paper specifically focuses on hybrid WMNs, which allow both mobile client devices as well as dedicated infrastructure nodes to form the network and provide routing and forwarding functionality. Hybrid WMNs are the most generic and most flexible type of mesh networks and are ideally suited to meet the requirements of incident area communications. However, current wireless mesh and ad-hoc routing protocols do not perform well in hybrid WMN, and are not able to establish stable and high throughput communication paths. One of the key reasons for this is their inability to exploit the typical high degree of heterogeneity in hybrid WMNs. SafeMesh, the routing protocol presented in this paper, addresses the limitations of current mesh and ad-hoc routing protocols in the context of hybrid WMNs. SafeMesh is based on the well-known AODV routing protocol, and implements a number of modifications and extensions that significantly improve its performance in hybrid WMNs. This is demonstrated via an extensive set of simulation results. We further show the practicality of the protocol through a prototype implementation and provide performance results obtained from a small-scale testbed deployment.

- by Jadwiga Indulska
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- Cognitive Science, Distributed Computing, Crisis Management, Emergency Response

We present the site-specific signal strength measurement results for path loss, shadowing, and fading in 2.4GHz band under typical harsh environment (high temperature 40-50 C and humidity 80-90%). We use spectrum analyzer Rohde & Schwarz FSH8 and InSSIDer (free software for WLANs). Measurements are taken in indoor and outdoor environments at various locations on different times of the day. An empirical channel model has been derived from these measurements that characterized the indoor-outdoor wireless channel which is suited for broadband multihop communications. This paper provides information that would be useful for the design and deployment of wireless mesh network in Qatar University.

- by Tamer Khattab
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- Wireless Mesh Networks, Free Software, High Temperature, Radio Propagation

Abstract--All communities whether they are rural or urban will have to respond to safety, disasters, and emergency situations. These situations place a special burden on communication systems for having a fully operational system. Given... more

- by A.S.M. Saifur Rahman
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- Terrorism, Disaster Management, Mesh Networks, Communication System

The Wireless Mesh Network (WMN) is ubiquitous emerging broadband wireless network. However, the open wireless medium, multi-hop multi-radio architecture and ad-hoc connectivity amongst endusers are such characteristics which increases the vulnerabilities of WMN towards many passive and active attacks. A secure network ensures the confidentiality, integrity and availability of wireless network. Integrity and availability is compromised by active attacks, while the confidentiality of end-users traffic is compromised by passive attacks. Passive attacks are silent in nature and do not harm the network traffic or normal network operations, therefore very difficult to detect. However, passive attacks lay down a foundation for later launching an active attack. In this article, we discuss the vulnerable features and possible passive threats in WMN along with current security mechanisms as well as future research directions. This article will serve as a baseline guide for the passive security threats and related issues in WMNs.

- by Jonathan Loo
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- Wireless Network, Wireless Mesh Network, Network Traffic

The conventional layered-protocol architecture does not provide optimal performance for wireless mesh networks (WMNs). The method of optimization decomposition of the protocol stack can achieve optimal network performance. This method usually results in a clean-slate protocol architecture that is different from the protocol architecture of WMNs. Such a difference actually demonstrates the need for a cross-layer design. Specific features pertaining to WMNs also show the need for cross-layer optimization across different protocol layers. In this paper, motivations for cross-layer design in WMNs are stated first. Moreover, cross-layer optimization schemes and algorithms between different protocol layers are investigated with an objective of shedding light on open research problems and new approaches. Guidelines for carrying out cross-layer design in WMNs are also provided in this paper.

- by Ian Akyildiz
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- Engineering, Technology, Network Performance, Wireless Mesh Network

The foregoing thesis is hereby approved as a creditable study in the area of Information Technology carried out and presented in a manner satisfactory to warrant its acceptance as a pre-requisite to the degree for which it has been submitted. It is understood that by this approval the undersigned do not necessarily endorse or approve any statement made, opinion expressed or conclusion drawn therein but approve the thesis only for the purpose for which it is submitted.

- by Karl-heinz Krempels
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- Protocols, Service discovery, Wireless Mesh Network

In this paper, we propose a new method, called Load-Aware Channel Assignment Exploiting Partially Overlapping Channels (Load-Aware CAEPO), which uses not only non-overlapping channels but also partially overlapping channels. We further improve our scheme by introducing the concept of node grouping to enhance the performance, and develop another new channel assignment algorithm called Load-Aware CAEPO-G. Simulation results demonstrate that our proposed schemes can significantly improve the aggregated network performance.

In the past a lot of effort has been put into resolving some of the major challenges of AdHoc networks especially the added ones brought up by the mobility of nodes and the absence of infrastructure in MANETs. Unlike MANETs, Wireless Mesh Networks (WMNs) provide flexibility in terms of mobility i.e. Mesh clients can be stationary or mobile and can form a client mesh network among themselves and with mesh routers. WMNs make use of multiple radios and multiple channels per radio for increased capacity, higher throughput and low interference. We gave an overview of the work done on MANETs, experimental Community Wireless Networks (CWNs) and Industrial solutions for mesh networks. We highlighted the differences between WMNS and MANETs and how WMNs can overcome the limitations of MANETs. This paper also compares the feasibility and scope of forecasted applications for MANETs and WMNs. In the end, we gave a conclusion about the commercial viability of MANETs and the growing scope of applications proposed for WMNs.

Wireless mesh network is a key technology for next generation wireless networking. Delay is regarded as a critical component in networks quality of service (QoS) especially the real-time applications become increasingly popular in recent years. In this paper, the queue control system of multi-interface multi-channel (MIMC) wireless mesh networks (WMNs) is modeled firstly, then we analyse the average queueing delay and the average queueing length, and optimize the average queueing delay by more network interfaces as well as transmitting rate of sending interfaces. Finally analytical explanation and simulation using ns-2 simulator show that use ing MIMC strategy in high traffic loading node is a good approach to optimize network performance, the average queueing delay in nodes with dual-channel dual-interface that do not interfere with each other can be reduced by about 30% compared to the single-channel single-interface.

- by xingping xian
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- Wireless Mesh Networks, Queueing theory, Control system, Optimization

Wireless mesh network is one the most potential application network for outdoor communication. In this presented work the security issues are investigated in WMN and a solution for security issue is designed more specifically for wormhole attack detection and prevention. The issues rise when the nodes are mobile and poor routing techniques allow a user to change or modify the information during data transmission because, during network communication the data is transmitted through the intermediate routers where any node can leave or join the network any time. Thus a malevolent node also can join the network and harm the privacy and security. This given scheme is desired to prepare for the secure communication route discovery which is able to provide the solution for defending routing based attacks in the network one of the attack is wormhole. Thus a novel key is desired to set up for the secure communication route sighting which is able to provide the solution for wormhole link atta...

- by vijay birchha
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- Network Security, Computer Networks, Wireless Mesh Networks, Wireless Mesh Network

Abstract. Wireless mesh networks (WMNs) have emerged as a key technology for next generation wireless broadband networks showing rapid progress and inspiring numerous compelling applications. A WMN comprises of a set of mesh routers (MRs) and mesh clients (MCs), where MRs are connected to the Internet backbone through the Internet gateways (IGWs). The MCs are wireless devices and communicate among themselves over possibly multi-hop paths with or without the involvement of MRs. User privacy and security have been primary concerns in WMNs due to their peer-to-peer network topology, shared wireless medium, stringent resource constraints, and highly dynamic environment. Moreover, to support real-time applications, WMNs must also be equipped with robust, reliable and efficient routing protocols so as to minimize the end-to-end latency. Design of a secure and efficient routing protocol for WMNs, therefore, is of paramount importance. In this paper, we propose an efficient and reliable rou...

- by Jaydip Sen
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- Data Privacy, Routing Protocol, Wireless Mesh Network, Robust estimator

Wireless Mesh Networks are currently emerging as a promising paradigm for broadband ubiquitous Internet access. However, their distributed nature raises many challenges when facing the increasing demand for multimedia applications, which require a tight control over the system's available resources. In this paper, we address such issue by introducing a mechanism combining service differentiation and packet aggregation in IEEE 802.11-based WMNs. Our architecture does not require any modification to the IEEE 802.11 MAC and can be readily deployed exploiting off-the-shelf hardware. The proposed solution has been implemented as an extension to the MIT Roofnet platform. Measurements run over a WiFi testbed show a large gain in the voice capacity attained. The source code, released under the BSD License, is made available to the research community.

The use of multiple channels can substantially improve the performance of wireless mesh networks. Considering that the IEEE PHY specification permits the simultaneous operation of three non-overlapping channels in the 2.4 GHz band and 12 non-overlapping channels in the 5 GHz band, a major challenge in wireless mesh networks is how to efficiently assign these available channels in order to optimize the network performance. We survey and classify the current techniques proposed to solve this problem in both single-radio and multi-radio wireless mesh networks. This paper also discusses the issues in the design of multi-channel protocols and architectures.

- by Karen Johanna
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- Wireless Communications, Ingeniería, Wireless Mesh Network

This paper is focused on broadband wireless mesh networks based on OFDMA resource management, considering a realistic SINR model of the physical layer with a fine tuned power control at each node. A linear programing model using column generation leads to compute power efficient schedules with high network capacity. Correlation between capacity and energy consumption is analyzed as well as the impact of physical layer parameters -SINR threshold and path-loss exponent. We highlight that there is no significant tradeoff between capacity and energy when the power consumption of idle nodes is important. We also show that both energy consumption and network capacity are very sensitive to the SINR threshold variation.

- by anis ouni
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- Linear Programming, Wireless Mesh Networks, Energy Consumption, Computer Model

The requirements and solutions for industrial wireless mesh networks are much more challenging and complicated than those for the consumer mesh networks. This puts additional stress on existing hardware chips on the market for wireless mesh networks, which started as products marketed towards consumers. The reason why we talk about the IEEE 802.15.4 chips is because most of the industrial wireless mesh network standards converge on IEEE 802.15.4 as the physical and MAC layer standards. In this paper we selectively chronicle the challenges we faced with the IEEE 802.15.4 chips, the products targeted with ZigBee for the consumer market, to advance WirelessHART, the technology targeted for industrial process control. We also describe our resolution over the challenges and offer our wish list for the next generation IEEE 802.15.4 chips. I.

- by Aloysius Mok
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- Process Control, Wireless Mesh Networks, Synchronization, Hardware

Wireless mesh networks (WMNs) consist of mesh routers and mesh clients, where mesh routers have minimal mobility and form the backbone of WMNs. They provide network access for both mesh and conventional clients. The integration of WMNs with other networks such as the Internet, cellular, IEEE 802.11, IEEE 802.15, IEEE 802.16, sensor networks, etc., can be accomplished through the gateway and bridging functions in the mesh routers. Mesh clients can be either stationary or mobile, and can form a client mesh network among themselves and with mesh routers. WMNs are anticipated to resolve the limitations and to significantly improve the performance of ad hoc networks, wireless local area networks (WLANs), wireless personal area networks (WPANs), and wireless metropolitan area networks (WMANs). They are undergoing rapid progress and inspiring numerous deployments. WMNs will deliver wireless services for a large variety of applications in personal, local, campus, and metropolitan areas. Despite recent advances in wireless mesh networking, many research challenges remain in all protocol layers. This paper presents a detailed study on recent advances and open research issues in WMNs. System architectures and applications of WMNs are described, followed by discussing the critical factors influencing protocol design. Theoretical network capacity and the state-ofthe-art protocols for WMNs are explored with an objective to point out a number of open research issues. Finally, testbeds, industrial practice, and current standard activities related to WMNs are highlighted.

- by Ian Akyildiz
- •
- Engineering, Technology, Remote Sensing, Computer Networks

Wireless mesh networks (WMNs) are multihop wireless networks with selfhealing and self-configuring capabilities. These features, plus the ability to provide wireless broadband connectivity at a comparatively low cost, make WMNs a promising technology for a wide range of applications. While discussing the suitability of WMN technology for public safety and crisis management communication, this article highlights its strengths and limitations and points to current and future research in this context. Quality of service. As a first priority, a public safety communication system must be able to provide reliable voice communication. Then, the system must transmit image and video data to allow rendering in acceptable quality. Beyond specifying that the call-setup time for voice communication should not exceed 250 milliseconds, the SoR report doesn't provide any other specific quantitative quality-of-service (QoS) requirements. Lastly, the system should be able

- by Marius Portmann
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- Distributed Computing, Crisis Management, Public Safety, Wireless Mesh Network

In this paper, we propose a novel node clustering algorithm with effective tax-based subcarrier allocation tailored for wireless mesh networks with quality-of-service support. With effective frequency reuse, our proposed approach is shown to achieve a higher system throughput than a conflict-graph approach and a baseline approach. Also, our approach is demonstrated promising in performance tradeoff between packet delay and end-to-end transmission rate.

- by Weihua Zhuang
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- Quality of Service, Wireless Mesh Network

The paper is devoted to modeling wireless mesh networks (WMN) through mixed-integer programming (MIP) formulations that allow to precisely characterize the link data rate capacity and transmission scheduling using the notion of time slots. Such MIP models are formulated for several cases of the modulation and coding schemes (MCS) assignment. We present a general way of solving the max-min fairness (MMF) traffic objective for WMN using the formulated capacity models. Thus the paper combines WMN radio link modeling with a non-standard way of dealing with uncertain traffic, a combination that has not, to our knowledge, been treated so far by exact optimization models. We discuss several ways, including a method based on the so called compatible or independent sets, of solving the arising MIP problems. We also present an extensive numerical study that illustrates the running time efficiency of different solution approaches, and the influence of the MCS selection options and the number of time slots on traffic performance of a WMN. Exact joint optimization modeling of the WMN capacity and the MMF traffic objectives forms the main contribution of the paper.

- by Michał Pióro
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- Distributed Computing, Linked Data, Ad Hoc Networks, Wireless Mesh Network

As one of the backup measures of intrusion prevention techniques, intrusion detection plays a paramount role in the second defense line of computer networks. Intrusion detection in wireless mesh networks (WMNs) is especially challenging and requires particular design concerns due to their special infrastructure and communication mode. In this paper, we propose a novel anomaly detection system, termed RADAR, to detect and handle anomalous mesh nodes in wireless mesh networks. Specifically, reputation is introduced to characterize and quantify a node's behavior in terms of fine-grained performance metrics of interest. The dual-core detection engine of RADAR then explores spatio-temporal property of such behavior to manifest the deviation between that of normal and anomalous nodes. Although the current RADAR prototype is only implemented with routing protocols, the design architecture allows it to be easily extended to cross-layer anomaly detection where anomalous events occur at different layers and can be resulted by either intentional intrusion or accidental network failure. The simulation results demonstrate that RADAR can achieve high detection accuracy, low computational complexity, and low false positive rate.

- by Zonghua Zhang
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- Computer Science, Distributed Computing, Network Security, Wireless Mesh Networks

Multicast is a key technology that provides efficient data communication among a set of nodes for wireless multi-hop networks. In sensor networks and MANETs, multicast algorithms are designed to be energy efficient and to achieve optimal route discovery among mobile nodes, respectively. However, in wireless mesh networks, which are required to provide high quality service to end users as the "last-mile" of the Internet, throughput maximization conflicting with scarce bandwidth has the paramount priority. We propose a Level Channel Assignment (LCA) algorithm and a Multi-Channel Multicast (MCM) algorithm to optimize throughput for multi-channel and multiinterface mesh networks. The algorithms first build a multicast structure by minimizing the number of relay nodes and hop count distances between the source and destinations, and use dedicated channel assignment strategies to improve the network capacity by reducing interference. We also illustrate that the use of partially overlapping channels can further improve the throughput. Simulations show that our algorithms greatly outperform the single-channel multicast algorithm. We observe that MCM achieves better throughput and shorter delay while LCA can be realized in distributed manner.

- by Li Xiao
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- Mobile Computing, Data Communication, Network Protocols, Sensor Network

The capacity of a multi-hop wireless network is the traffic payload that it can transport. This is a prominent quality of service issue, particularly in the highly constrained settings of 802.11 wireless mesh network. In this paper, we consider two complementary definitions of the capacity. A network-wise capacity is defined as the sum of the upload traffic, and a flow-wise capacity highlighting the unfairness among traffic flows. We study the behavior of these capacities face to several parameters: routing protocols, number and location of gateways bridging the network to the Internet, and the physical network topology. Thorough simulations highlight the insensitivity of the capacity face to these parameters while it is directly related to the congestion around the gateway. Furthermore, we show that if the number of gateways increases, the capacity tends to a maximum boundary.

- by anis ouni
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- Wireless Communications, Routing, Wireless Mesh Network, Network Topology

This paper describes three design values that we apply for designing playful interactions. Interactive play objects can stimulate social interaction and physical play by providing motivating feedback to players' behavior; they can allow players to create their own game goals and rules in an open-ended play context and support social player interaction patterns. This design approach is illustrated by six design cases in which our assumptions were examined in various play contexts. The results show that the application of these design values can lead to rich and appealing innovative play concepts. Players can create a wide range of (physical) games using open-ended play objects, and properties of the play objects, such as being personal or shared, influence the type of social interaction.

- by Vero Vanden Abeele
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- Information Systems, Cognitive Science, Social Psychology, Image Processing

In the recent past, there has been a tremendous increase in the popularity of VoIP services as a result of huge growth in broadband access. The same VoIP service poses new challenges when deployed over a wireless mesh network while enabling users to make voice calls using WiFi phones. Packet losses and delay due to interference in a multiple hop mesh network with limited capacity can significantly degrade the end-to-end VoIP call quality.

- by Samrat Ganguly
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- Distributed Computing, Voice over IP, Quality of Service, Wireless Mesh Network

Broadband wireless networks are providing internet and related services to end users. The three most important broadband wireless technologies are IEEE 802.11, IEEE 802.16, and Wireless Mesh Network (WMN). Security attacks and vulnerabilities vary amongst these broadband wireless networks because of differences in topologies, network operations and physical setups. Amongst the various security risks, Denial of Service (DoS) attack is the most severe security threat, as DoS can compromise the availability and integrity of broadband wireless network. In this paper, we present DoS attack issues in broadband wireless networks, along with possible defenses and future directions.

- by Jonathan Loo
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- DoS Attack, Wireless Network, Wireless Technology, Wireless Mesh Network

Broadband wireless access networks are promising technology for providing better end user services. For such networks, designing a scheduling algorithm that fairly allocates the available bandwidth to the end users and maximizes the overall network throughput is a challenging task. In this paper, we develop a centralized fair scheduling algorithm for IEEE 802.16 mesh networks that exploits the spatio-temporal bandwidth reuse to further enhance the network throughput. The proposed mechanism reduces the length of a transmission round by increasing the number of non-contending links that can be scheduled simultaneously. We also propose a greedy algorithm that runs in polynomial time. Performance of the proposed algorithms is evaluated by extensive simulations. Results show that our algorithms achieve higher throughput than that of the existing ones and reduce the computational complexity.

- by Abdul Hamid
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- Service Quality, Scheduling, Wireless Mesh Networks, Equity
- by Fahad Samad
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- Computer Science, Spine, Routing, Wireless Sensor Networks