MESH NETWORK

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.

This paper investigates implementation and design issues for a heterogeneous network for structural monitoring. The proposed application uses wireless sensors and the controller area network (CAN) to provide energy efficient monitoring. The contributions include: implementation of the PIC18f4680 platform in TinyOS, creating a message protocol over CAN, and developing a sensor board.

In order to maximize the system throughput, future wireless communication systems will employ a very tight frequency reuse. This leads to interference limited systems where the interference is high at the cell edges. The key ingredient to such networks are thus receivers that are able to exploit the structure of this interference instead of nulling or attenuating it. In this paper we apply such a receiver structure to a distributed multiple-input multiple-output (MIMO) scenario to decode two independent data streams from two synchronized base stations. Further we show how the distributed MIMO receiver is implemented in real-time on the OpenAirInterface platform and provide results from field trials and compare them to the simulation results. Applications of the distributed MIMO receiver include single-frequency cellular as well as mesh networks. OpenAirInterface is an experimental open-source real-time hardware and software platform for experimentation in wireless communications and signal processing. Its current implementation provides a full software modem comprising physical and link layer functionalities for cellular and mesh network topologies.

We present a novel distributed 'virtual localization'method for mesh networks, such as sensor meshes, which does not depend on radio ranging or the existence of anchor nodes. We show in simulation that it can be used for establishing efficient and reliable location-based routing information.

Proper analysis and understanding of security requirements are important because they help us to discover any security or requirement defects or mistakes in the early stages of development. Hence, security requirements engineering is both a central task and a critical success factor in product line development due to the complexity and extensive nature of product lines. However, most of the current product line practices in requirements engineering do not adequately address security requirements engineering. Therefore, in this paper we will propose a security quality requirements engineering process (SREPPLine) driven by security standards and based on a security requirements decision model along with a security variability model to manage the variability of the artefacts related to security requirements. The aim of this approach is to deal with security requirements from the early stages of the product line development in a systematic way, in order to facilitate conformance with the most relevant security standards with regard to the management of security requirements, such as ISO/IEC 27001 and ISO/IEC 15408.

This letter proposes the enhanced hierarchical routing protocol (EHRP) for ZigBee Mesh Networks. The EHRP finds the shortest hierarchical path based on the ZigBee hierarchical addressing scheme. The EHRP provides efficient and reliable routing paths. In addition, the EHRP is completely compatible with ZigBee v.1.0 standard. Simulation results demonstrate that the EHRP reduces routing overhead and route discovery delay of ZigBee mesh networks significantly compared with the hierarchical routing protocol (HRP) defined in ZigBee v1.0.

Mesh networks are candidate to play the role of switched Ethernet LANs over extended areas and with a sensibly higher flexibility. Actually, mesh networks can exploit both Ethernet and wireless technologies, e.g. Wi-Fi and/or free-space optical links, to provide a high degree of redundancy in an access network, and to provide users with powerful means to connect with each other.

The admittance summation method is efficient in short circuit analysis of radial and weakly meshed networks. It is especially powerful if all node loads can be represented as any combination of constant impedance and constant current load component. However, in the existing literature one cannot find any explanation how to handle power transformer in that approach. For that reason, the corresponding equations have been developed in this paper along with a procedure for development of a three-winding transformer admittance matrix. In addition, a procedure for handling an arbitrary load was proposed. A large number of tests were performed and results were compared with that obtained by the previously published method. As an illustration, some of the results for single fault currents are presented. It can be concluded that the proposed approach makes the admittance summation method capable to take into account all network elements in a proper way.

Data centers' energy consumption has attracted global attention because of the fast growth of the information technology (IT) industry. Up to 60% of the energy consumed in a data center is used for cooling in wasteful ways as a result of lack of environmental information and overcompensated cooling systems. In this project, a wireless sensor network for data-enter environmental monitoring was developed to improve energy efficiency and to optimize data-center performance. The sensor network consists of a suite of sensor nodes for data sensing, a router node to relay sensed data, and a coordinator node to establish a network, receive the data, and process the data. The prototype sensor network was built on Arduino open source hardware with a seamlessly integrated XBee RF module and configured to operate within the ZigBee mesh network standard. A 24-hour test run at Argonne's data center demonstrated that the wireless networked environmental monitoring solution is easy to integrate and manage with the existing IT infrastructure, while delivering better visibility into the data center's 3D temperature and humidity distribution and substantial improvements in energy efficiency.

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

Although IEEE 802.15.4 is being considered as a promising standard for low-cost low-power Wireless Sensor Networks (WSNs), several issues in the specification are still open. One of those open issues is how to build a synchronized multi-hop mesh network for power efficient, scalable, and robust networking. In fact, while the current specification supports multi-hop networking using peer-to-peer topology, it restricts its use to the beaconless mode. This paper presents an extension to the current IEEE 802.15.4 standard in which mesh networking in the low power beacon mode is enabled through the use of distributed beacon scheduling. The work presented in this paper has been implemented on top of the Open-ZB IEEE 802.15.4 implementation within the TinyOS operating system. The feasibility of our proposal is demonstrated and evaluated through both physical test-bed and computer based emulation.

This paper is an introduction to survivability of WDM networks. All the main optical protection techniques proposed as far as now for the WDM layer are classified and reviewed. In particular, commonly adopted protection strategies for ring and mesh networks are explained. Moreover, off-line planning of WDM networks able to support path protection is briefly introduced. Finally, an example of heuristic network-capacity optimization is presented, discussing results obtained by considering a case-study 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.

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.

A novel model for detecting leaks in complex pipeline network systems has been developed. The model derives from the theory of Liapunov stability criteria. A leak is detected if the resulting eigenvalues from the deviation flow matrix have values less than a predetermined value. An advanced mesh network algorithm was used to decompose the complex pipeline network system into sub-networks. The flow model (equations of motion and continuity) which incorporates a leaking factor, k L , is solved by a numerical technique that uses the method of characteristics and an implicit finite function. The unsteady state flow matrix of the complex pipeline network system was analysed using a modified Hardy Cross algorithm, where the velocity and pressure were computed for each node and pipeline loop in the complex network. The plots for the characteristic pressure and velocity eigenvalues show that pressure measurements are faster parameters for leak detection than volume measurements. Volume measurements appear to be suitable for larger leak systems and longer response time.

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.

Over the last two decades free-space optical communication (FSO) has become more and more interesting as an adjunct or alternative to radio frequency communication. Free-space optical (FSO) communication links are most susceptible to a tremendous amount of variability and offer a real challenge for efficient, robust system design.one method of transmitting information from one place to another by sending pulses of light through an optical fiber is Fiber-optic communication , FSO communication systems will provide a large dynamic range of performance through most cases .It is a line-of-sight (LOS) technology that transmits a modulated beam of visible or infrared light through the atmosphere for broadband communications. In a way similar to fiber optical communications, free space optics uses a light emitting diode (LED) or laser (light amplification by stimulated emission of radiation) as a point source for data transmission. However, in free space optics, an energy beam is collimate...

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.

In this paper, we address the following two questions concerning the capacity and configuration of fixed wireless networks: (i) given a set of wireless nodes with arbitrary but fixed locations, and a set of data flows, what is the max-min achievable throughput? and (ii) how should the network be configured to achieve the optimum? We consider these questions from a networking standpoint assuming point-to-point links, and employ a rigorous physical layer model to model conflict relationships between them. Since we seek capacity results, we assume that the network is operated using an appropriate schedule of conflict-free link activations. We develop and investigate a novel optimization framework to determine the optimal throughput and configuration, i.e., flow routes, link activation schedules and physical layer parameters. Determining the optimal throughput is a computationally hard problem, in general. However, using a smart enumerative technique we obtain numerical results for several different scenarios of interest. We obtain several important insights into the structure of the optimal routes, schedules and physical layer parameters. Besides determining the achievable throughput, we believe that our optimization-based framework can also be used as a tool, for configuring scheduled wireless networks, such as those based on IEEE 802.16.

A new decomposition method is presented that includes the network through ac modeling within the hydrothermal scheduling optimization process including the losses. In short-term hydrothermal scheduling, the transmission network is typically modeled with dc power flow techniques. Such modeling, however, can lead to impractical solutions when it is verified with ac power flow. Another proposal considers in thermal systems the ac network modeling but not the optimization of losses. The approach presented here addresses issues such as congestion management and control of service quality that often arise in large and weakly meshed networks-the typical pattern of power systems in Latin America. Generalized Benders decomposition and traditional, well-known optimization techniques are used to solve this problem. The master problem stage defines the generation levels by regarding the inter-temporal constraints, whereas the subproblem stage determines both the active and the reactive economical dispatches for each time interval of the load curve. It meets the electrical constraints through a modified ac optimal power flow (OPF). Another important contribution is the inclusion of accelerating techniques aimed at reducing the number of iterations and CPU time. The methodology was proven in a real system and test systems. Results are discussed in this paper.

This paper attempts to study the impact of wavelength converters in WDM wavelength routed all-optical networks. A new heuristic approach for placement of wavelength converters to reduce blocking probabilities is explored. Multihop virtual topology is designed to minimize the number and overall cost of the converters. Blocking probabilities for Static Lightpath Establishment (SLE) and Dynamic Lightpath Establishment (DLE) are analyzed. In the case of SLE, arranging lightpaths in ascending order of their path length reduces blocking probability. Wavelength converters placed at nodes with high nodal degree further reduces the blocking probabilities. Simulation studies performed on 28-node USA long haul network, 20-node arbitrary mesh network, and 19-node EON (European Optical Network) validate the observations made earlier.

A critical review is presented in this paper on parallel computing, including parallel algorithms and parallel architectures. Emphasis is laid on different interconnection networks, including recent efficient multi-mesh network. The role of parallel computing for design and analysis of adaptive sampling are pointed out. Different parallel computing platforms and their basic characteristics, along with some computing paradigms that are used in conjunction with adaptive designs are discussed. Some fundamental physical and numerical issues related to constructing modern numerical MHD codes for space weather prediction are outlined. Efficient execution of scientific simulations on high-performance parallel computers is focused. Scope for future development is also suggested.

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.

This paper has outlined a method (called OBGP) of extending BGP to support lightpath setup and management across an optical network. The development of OBGP has been discussed by reviewing current BGP behavior and design requirements for OBGP. An implementation of OBGP using simulation tools has been presented, along with initial test results, which have shown that a seamless migration from BGP to OBGP is possible.

SUMMARY In this paper we present a method for establishing the value of a network's components from a reliability worth perspective. The method can be applied to a general distribution system i.e. both for radial and meshed network systems. Moreover, this paper shows results from an application study for a rural network system that is dominated by overhead lines. The

There is a potential for significant cost, footprint and power savings by eliminating unnecessary Opto-Electronic (OE) conversions on a signal path in a core optical mesh network. This paper addresses and clarifies some fundamental issues surrounding all-optical networking and all-optical switching and analyzes the tradeoffs between transparent (no OE conversions) and opaque networking (with OE conversions). It investigates a number of networking and interface compatibility issues that arise for an opaque network with transparent switches and presents a number of ways on how this issues can be addressed.

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.

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.

IEEE 802.15.4 is an emerging next generation wireless standard specifically designed for low-rate wireless personal area networks (LR-WPAN) which suit wireless sensor networks applications. It attempts to provide a low cost, low power and short range wireless networking. The QoS is more challenging in heterogeneous wireless sensors networks where a diverse mixture of sensors for monitoring temperature, pressure, and humidity are deployed to monitor the phenomena, thereby introducing different reading rates at these sensors. In this paper, we have simulated the performance analysis of Quality of Service parameters of WSN based on IEEE 802.15.4 mesh topology using reactive MANET routing in QualNet 4.5 on multiple traffic types. The data packet delivery ratio, average end-to-end delay, total energy consumption and network lifetime are investigated as the performance metrics. The results show that DSR and DYMO perform better than AODV in mesh topology non beacon enabled mode.

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.

Packet-based on-chip networks are increasingly being adopted in complex System-on-Chip (SoC) designs supporting numerous homogeneous and heterogeneous functional blocks. These Network-on-Chip (NoC) architectures are required to not only provide ultra-low latency, but also occupy a small footprint and consume as little energy as possible. Further, reliability is rapidly becoming a major challenge in deep sub-micron technologies due to the increased prominence of permanent faults resulting from accelerated aging effects and manufacturing/testing challenges.

The bandwidth of a wavelength channel in WDM optical networks is very high compared to the user's requirements for various applications. Therefore, there is a scope for better utilization of channel bandwidth by traffic grooming, in which several user's channels are multiplexed for transmission over a single channel. Several research works have been reported on traffic grooming routing and wavelength assignment (GRWA) for static and dynamic traffic pattern under centralized environment. Distributed dynamic grooming routing and wavelength assignment (DDGRWA) is a new and quite unexplored area in WDM optical mesh networks. This article introduces the concept of distributed traffic grooming in WDM mesh networks which also includes virtual topology construction, reconfiguration, routing and wavelength assignment in the distributed environment assuming incoming traffic to be dynamic in nature. We have also presented simulation results of our algorithm on dynamically generated traffic under various network topologies.

This paper describes an INtrusion-tolerant routing protocol for wireless SEnsor NetworkS (INSENS). INSENS securely and efficiently constructs tree-structured routing for wireless sensor networks (WSNs). The key objective of an INSENS network is to tolerate damage caused by an intruder who has compromised deployed sensor nodes and is intent on injecting, modifying, or blocking packets. To limit or localize the damage caused by such an intruder, INSENS incorporates distributed lightweight security mechanisms, including efficient oneway hash chains and nested keyed message authentication codes that defend against wormhole attacks, as well as multipath routing. Adapting to WSN characteristics, the design of INSENS also pushes complexity away from resource-poor sensor nodes towards resource-rich base stations. An enhanced single-phase version of INSENS scales to large networks, integrates bidirectional verification to defend against rushing attacks, accommodates multipath routing to multiple base stations, enables secure joining/leaving, and incorporates a novel pairwise key setup scheme based on transitory global keys that is more resilient than LEAP. Simulation results are presented to demonstrate and assess the tolerance of INSENS to various attacks launched by an adversary. A prototype implementation of INSENS over a network of MICA2 motes is presented to evaluate the cost incurred. q 2005 Published by Elsevier B.V. Computer Communications xx (xxxx) 1-15 www.elsevier.com/locate/comcom 0140-3664/$ -see front matter q 2005 Published by Elsevier B.V.

Spatial reuse in a mesh network can allow multiple communications to proceed simultaneously, hence proportionally improve the overall network throughput. To maximize spatial reuse, the MAC protocol must enable simultaneous transmitters to maintain the minimal separation distance that is sufficient to avoid interference. This paper demonstrates that physical carrier sensing enhanced with a tunable sensing threshold is effective at avoiding interference in 802.11 mesh networks without requiring the use of virtual carrier sensing. We present an analytical model for deriving the optimal sensing threshold given network topology, reception power, and data rate. A distributed adaptive scheme is also presented to dynamically adjust the physical carrier sensing threshold based on periodic estimation of channel conditions in the network. Simulation results are shown for large-scale 802.11b and 802.11a networks to validate both the analytical model and the adaptation scheme. It is demonstrated that the enhanced physical carrier sensing mechanism effectively improves network throughput by maximizing the potential of spatial reuse. With dynamically tuned physical carrier sensing, the end to end throughput approaches 90% of the predicted theoretical upper-bound assuming a perfect MAC protocol, for a regular chain topology of 90 nodes.

Innovative asynchronous circuits are central to the Ethernet switch chips from Intel's Switch and Router Division (formerly Fulcrum Microsystems). These circuits are complex, and it can be hard to gauge their benefits since there are few direct comparisons. For this paper, we apply the technology and tool flow developed for these commercial products to a familiar benchmark: a network of general purpose processors on a chip. The processor is a single-issue 32-bit integer RISC core, a fromscratch implementation mostly compatible with the MIPS R3000. The network uses a 16-port 32-bit fully connected Nexus crossbar. We achieve greater scalability by linking these crossbars in a 2D mesh with clusters of 8 cores and 4 cardinal and 4 diagonal links per tile. Each core has 64KB of local memory and can access the memory of any other core in the mesh. Our design makes heavy use of the Proteus synthesis, place & route flow, as well as existing custom cells. It required only a few man-months of effort to develop a complete gate-level design and physical floorplan which can run simple C programs such as Dhrystone. A few more man-months will produce a test chip, expected in 2013.

We evaluate several routing protocols for mobile, wireless, ad hoc networks via packet level simulations. The protocol suite includes routing protocols specifically designed for ad hoc routing, as well as more traditional protocols, such as link state and distance vector, used for dynamic networks. Performance is evaluated with respect to fraction of packets delivered, end-to-end delay and routing load for a given traffic and mobility model. It is observed that the new generation of on-demand routing protocols use much lower routing load. However, the traditional link state and distance vector protocols provide, in general, better packet delivery and delay performance.

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.

Worldwide there has been increasing interest over the past few years for so-called "Smart Meters", in academia, governments and in industry. Such smart-metering systems need a way to communicate the collected data reliably and cost efficiently to the back-office for analysis. Several competing technologies exist and are in use world-wide. Meshnetworks have been the winning technology in the USA and Australia for the past two years, and are gaining interest in Europe at the moment due to its reduced costs and increased reliability. In this paper we present and evaluate a real-life implementation of a new routing protocol for use in smart-metering mesh-network grids. The routing protocol we present is designed with both technological constraints and legislative requirements as posed by the application area in mind. Our evaluation of the protocol is based on real-world experience and data collected from real-world devices, in combination with simulation studies of the protocol. Our evaluation shows that the protocol is a robust, reliable solution for communicating collected data in difficult scenarios, showing great resilience against both bit-errors and node-failures.

Nowadays, critical control systems are a fundamental component contributing to the overall performance of critical infrastructures in our society, most of which belong to the industrial sector. These complex systems include in their design different types of information and communication technology systems, such as wireless (mesh) sensor networks, to carry out control processes in real time. This fact has meant that several communication standards, such as Zigbee PRO, WirelessHART, and ISA100.11a, have been specified to ensure coexistence, reliability, and security in their communications. The main purpose of this paper has been to review these three standards and analyze their security. We have identified a set of threats and potential attacks in their routing protocols, and we consequently provide recommendations and countermeasures to help Industry protect its infrastructures.

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.