Showing papers on "Wireless mesh network published in 2010"

IEEE 802.11s: The WLAN Mesh Standard

Abstract: The wireless local area network standard IEEE 802.11 is the preferred solution for lowcost data services. Key to its success are the 2.4 and 5 GHz unlicensed bands. The transmit power limitations imposed due to regulatory requirements limit the range (coverage) that can be achieved by WLANs in these bands. However, the demand for "larger" wireless infrastructure is emerging, ranging from office/university campuses to city-wide deployments. To overcome the limitations of singlehop communication, data packets need to traverse over multiple wireless hops, and wireless mesh networks are called for. Since 2004 Task Group S has been developing an amendment to the 802.11 standard to exactly address the aforementioned need for multihop communication. Besides introducing wireless frame forwarding and routing capabilities at the MAC layer, the 802.11s amendment brings new interworking and security. In this article, we provide insights into the latest developments in 802.11s and explain how the overall mesh concept fits into the 802 set of networking standards.

Rethinking Indoor Wireless Mesh Design: Low Power, Low Frequency, Full-Duplex

Abstract: Existing indoor WiFi networks in the 2.5GHz and 5 GHz use too much transmit power, needed because the high carrier frequency limits signal penetration and connectivity. Instead, we propose a novel indoor wireless mesh design paradigm, based on Low Frequency, using the newly freed white spaces previously used as analogue TV bands, and Low Power - 100 times less power than currently used. Preliminary experiments show that this maintains a similar level of connectivity and performance to existing networks. It also yields more uniform connectivity, thus simplifies MAC and routing protocol design. We also advocate full-duplex networking in a single band, which becomes possible in this setting (because we operate at low frequencies). It potentially doubles the throughput of each link and eliminates hidden terminals.

WirelessHART™: Real-Time Mesh Network for Industrial Automation

Abstract: WirelessHART: Real-Time Mesh Network for Industrial Automation presents the WirelessHART Standard in detail and wireless industrial automation in general. This book strives to facilitate the adoption of wireless technology in industrial automation, and introduces the research potential of the wireless industrial automation to the academics. This book is designed for practitioners and researchers working in the wireless process industry. Advanced-level students and researchers focusing on engineering and computer science will find this book valuable as a secondary text or reference book. "This is the first book in the area. I can anticipate a large international market for it that would include any company with process controls operations: Petrochemical, Chemical companies, Food and Beverage, Pulp and Paper, Pharmaceuticals, etc," - Dr. Jose A. Gutierrez of Emerson About WirelessHART: WirelessHART is a cutting-edge standard for the wireless process industry (such as oil, gas, pharmaceutical, chemical, pulp & paper, power plant, and companies such as ABB, Emerson Process Management, Endress+Hauser, MACTek, Pepperl+Fuchs, Siemens and more). This new standard provides a robust wireless mesh network protocol, and assists users with a quicker and smoother experience when operating their wireless technologies.

SourceSync: a distributed wireless architecture for exploiting sender diversity

Abstract: Diversity is an intrinsic property of wireless networks. Recent years have witnessed the emergence of many distributed protocols like ExOR, MORE, SOAR, SOFT, and MIXIT that exploit receiver diversity in 802.11-like networks. In contrast, the dual of receiver diversity, sender diversity, has remained largely elusive to such networks.This paper presents SourceSync, a distributed architecture for harnessing sender diversity. SourceSync enables concurrent senders to synchronize their transmissions to symbol boundaries, and cooperate to forward packets at higher data rates than they could have achieved by transmitting separately. The paper shows that SourceSync improves the performance of opportunistic routing protocols. Specifically, SourceSync allows all nodes that overhear a packet in a wireless mesh to simultaneously transmit it to their nexthops, in contrast to existing opportunistic routing protocols that are forced to pick a single forwarder from among the overhearing nodes. Such simultaneous transmission reduces bit errors and improves throughput. The paper also shows that SourceSync increases the throughput of 802.11 last hop diversity protocols by allowing multiple APs to transmit simultaneously to a client, thereby harnessing sender diversity. We have implemented SourceSync on the FPGA of an 802.11-like radio platform. We have also evaluated our system in an indoor wireless testbed, empirically showing its benefits.

Engineering wireless mesh networks: joint scheduling, routing, power control, and rate adaptation

Abstract: We present a number of significant engineering insights on what makes a good configuration for medium- to large-size wireless mesh networks (WMNs) when the objective function is to maximize the minimum throughput among all flows. For this, we first develop efficient and exact computational tools using column generation with greedy pricing that allow us to compute exact solutions for networks significantly larger than what has been possible so far. We also develop very fast approximations that compute nearly optimal solutions for even larger cases. Finally, we adapt our tools to the case of proportional fairness and show that the engineering insights are very similar.

Applications of Geometric Algorithms to Reduce Interference in Wireless Mesh Network

Abstract: In wireless mesh networks such as WLAN (IEEE 802.11s) or WMAN (IEEE 802.11), each node should help to relay packets of neighboring nodes toward gateway using multi-hop routing mechanisms. Wireless mesh networks usually intensively deploy mesh nodes to deal with the problem of dead spot communication. However, the higher density of nodes deployed, the higher radio interference occurred. This causes significant degradation of system performance. In this paper, we first convert network problems into geometry problems in graph theory, and then solve the interference problem by geometric algorithms. We first define line intersection in a graph to reflect radio interference problem in a wireless mesh network. We then use plan sweep algorithm to find intersection lines, if any; employ Voronoi diagram algorithm to delimit the regions among nodes; use Delaunay Triangulation algorithm to reconstruct the graph in order to minimize the interference among nodes. Finally, we use standard deviation to prune off those longer links (higher interference links) to have a further enhancement. The proposed hybrid solution is proved to be able to significantly reduce interference in a wireless mesh network in O(n log n) time complexity.

Network coding-aware routing in wireless networks

Abstract: A recent approach--COPE, presented by Katti et al. (Proc. ACM SIGCOMM 2006, pp. 243-254)--for improving the throughput of unicast traffic in wireless multihop networks exploits the broadcast nature of the wireless medium through opportunistic network coding. In this paper, we analyze throughput improvements obtained by COPE-type network coding in wireless networks from a theoretical perspective. We make two key contributions. First, we obtain a theoretical formulation for computing the throughput of network coding on any wireless network topology and any pattern of concurrent unicast traffic sessions. Second, we advocate that routing be made aware of network coding opportunities rather than, as in COPE, being oblivious to it. More importantly, our model considers the tradeoff between routing flows close to each other for utilizing coding opportunities and away from each other for avoiding wireless interference. Our theoretical formulation provides a method for computing source-destination routes and utilizing the best coding opportunities from available ones so as to maximize the throughput. We handle scheduling of broadcast transmissions subject to wireless transmit/receive diversity and link interference in our optimization framework. Using our formulations, we compare the performance of traditional unicast routing and network coding with coding-oblivious and coding-aware routing on a variety of mesh network topologies, including some derived from contemporary mesh network testbeds. Our evaluations show that a route selection strategy that is aware of network coding opportunities leads to higher end-to-end throughput when compared to coding-oblivious routing strategies.

Efficient Multicast Algorithms for Multichannel Wireless Mesh Networks

Abstract: The wireless mesh network is an emerging technology that provides high quality service to end users as the "last milerdquo of the Internet. Furthermore, multicast communication is a key technology for wireless mesh networks. Multicast provides efficient data distribution among a group of nodes. However, unlike other wireless networks, such as sensor networks and MANETs, where multicast algorithms are designed to be energy efficient and to achieve optimal route discovery among mobile nodes, wireless mesh networks need to maximize throughput. This paper proposes two multicast algorithms: the level channel assignment (LCA) algorithm and the multichannel multicast (MCM) to improve the throughput for multichannel and multi-interface mesh networks. The algorithms build efficient multicast trees by minimizing the number of relay nodes and total hop count distances of the trees. The algorithms use dedicated channel assignment strategies to reduce the interference to improve the network capacity. We also demonstrate that using partially overlapping channels can further diminish the interference. Furthermore, additional interfaces help to increase the bandwidth, and multiple gateways can further shorten the total hop count distance. Simulations show that those algorithms greatly outperform the single-channel multicast algorithm. We also observe that MCM achieves better throughput and shorter delay while LCA can be realized in distributed manner.

Routing, scheduling and channel assignment in Wireless Mesh Networks: Optimization models and algorithms

Abstract: Wireless Mesh Networks (WMNs) can partially replace the wired backbone of traditional wireless access networks and, similarly, they require to carefully plan radio resource assignment in order to provide the same quality guarantees to traffic flows. In this paper we study the radio resource assignment optimization problem in Wireless Mesh Networks assuming a time division multiple access (TDMA) scheme, a dynamic power control able to vary emitted power slot-by-slot, and a rate adaptation mechanism that sets transmission rates according to the signal-to-interference-and-noise ratio (SINR). The proposed optimization framework includes routing, scheduling and channel assignment. Quality requirements of traffic demands are expressed in terms of minimum bandwidth and modeled with constraints defining the number of information units (packets) that must be delivered per frame. We consider an alternative problem formulation where decision variables represent compatible sets of links active in the same slot and channel, called configurations. We propose a two phases solution approach where a set of configurations is first selected to meet traffic requirements along the best available paths, and then configurations are assigned to channels according to device characteristics and constraints. The optimization goal is to minimize the number of used slots, which is directly related to the global resource allocation efficiency. We provide a lower bound of the optimal solution solving the continuous relaxation of problem formulation. Moreover, we propose a heuristic approach to determine practical integer solutions (upper bound). Since configuration variables are exponentially many, our solution approaches are based on the column generation technique. In order to assess the effectiveness of the proposed algorithms we show the numerical results obtained on a set of realistic-size randomly generated instances.

Mesh network door lock

Abstract: Systems and methods are disclosed for sending a code from a mesh network key and wirelessly communicating the code with one or more mesh network appliances over a mesh network such as ZigBee; receiving the code over the mesh network by a mesh network lock controller; and providing access to the secured area upon authenticating the code.

mTreebone: A Collaborative Tree-Mesh Overlay Network for Multicast Video Streaming

Abstract: Recently, application-layer overlay networks have been suggested as a promising solution for live video streaming over the Internet. To organize a multicast overlay, a natural structure is a tree, which, however, is known vulnerable to end-hosts dynamics. Data-driven approaches address this problem by employing a mesh structure, which enables data exchanges among multiple neighbors, and thus, greatly improves the overlay resilience. It unfortunately suffers from an efficiency-delay trade-off, because data have to be pulled from mesh neighbors by using extra notifications periodically. In this paper, we closely examine the contributions of overlay nodes, and argue that performance of a mesh overlay closely depends on a small set of stable backbone nodes. This is validated through a real trace study on PPLive, the largest commercial application-layer live streaming system to date. Motivated by this observation, we then suggest a novel collaborative tree-mesh design that leverages both mesh and tree structures. The key idea is to identify a set of stable nodes to construct a tree-based backbone, called treebone, with most of the data being pushed over this backbone. These stable nodes, together with others, are further organized through an auxiliary mesh overlay, which facilitates the treebone to accommodate node dynamics and fully exploit the available bandwidth between overlay nodes. This hybrid design, referred to as mTreebone, brings a series of unique and critical design challenges. In particular, the identification of stable nodes and seamless data delivery using both push and pull methods. In this paper, we present optimized solutions to these problems, which reconcile the two overlays under a coherent framework with controlled overhead. We evaluate mTreebone through both simulations and PlanetLab experiments. The results demonstrate the superior efficiency and robustness of this hybrid solution in both static and dynamic scenarios.

Performance Comparison and Analysis of DSDV and AODV for MANET

Abstract: A Mobile Ad hoc NETwork (MANET) is a kind of wireless ad-hoc network, and is a self-configuring network of mobile routers (and associated hosts) connected by wireless links – the union of which forms an arbitrary topology. The routers are free to move randomly and organize themselves arbitrarily; thus, the network's wireless topology may change rapidly and unpredictably. Such a network may operate in a standalone fashion, or may be connected to the larger Internet.

A game theory based reputation mechanism to incentivize cooperation in wireless ad hoc networks

Abstract: In wireless ad hoc networks one way to incentivize nodes to forward other nodes' packets is through the use of reputation mechanisms, where cooperation is induced by the threat of partial or total network disconnection if a node acts selfishly. The problem is that packet collisions and interference may make cooperative nodes appear selfish sometimes, generating unnecessary and unwanted punishments. With the use of a simple network model we first study the performance of some proposed reputation strategies and then present a new mechanism called DARWIN (Distributed and Adaptive Reputation mechanism for Wireless ad hoc Networks), where we try to avoid retaliation situations after a node is falsely perceived as selfish to help restore cooperation quickly. Using game theory, we prove that our mechanism is robust to imperfect measurements, is collusion-resistant and can achieve full cooperation among nodes. Simulations are presented to complement our theoretical analysis and evaluate the performance of our algorithm compared to other proposed reputation strategies.

The w-iLab.t Testbed

Abstract: In this paper, the W-iLab.t wireless testbed is presented. The testbed consists of nearly 200 sensor nodes and an equal amount of WiFi nodes, which are installed across three floors of an office building. The testbed supports wireless sensor experiments, WiFi based mesh and ad hoc experiments, and mixed sensor/WiFi experiments. It is explained how changes in the environment of the sensor nodes can be emulated and how experiments with heterogeneous wireless nodes are enabled. Additional features of the testbed are listed and lessons learned are presented that will help researchers to construct their own testbed infrastructure or add functionality to an existing testbed. Finally, it is argued that deep analysis of unexpected testbed behavior is key to understanding the dynamics of wireless network deployments.

Mesh routing method and mesh routing apparatus in beacon enabled wireless AD-HOC networks

Abstract: There is provided a mesh routing method in beacon-enabled wireless AD-HOC networks that includes: broadcasting, by nodes constituting a wireless AD-HOC network, a beacon message loading neighbor node information on a beacon payload; managing, by a node receiving the broadcasted beacon message, its own neighbor node table by extracting the neighbor node information loaded on the beacon payload; and performing, by a source node attempting to transmit data or commands, mesh routing on the basis of its own neighbor node table.

SlideOR: Online Opportunistic Network Coding in Wireless Mesh Networks

Abstract: Opportunistic routing significantly increases unicast throughput in wireless mesh networks by effectively utilizing the wireless broadcast medium. With network coding, opportunistic routing can be implemented in a simple and practical way without resorting to a complicated scheduling protocol. Traditionally, due to the constraints of computational complexity, a protocol utilizing network coding needs to partition the data into multiple segments and encode only packets in the same segment. However, it is extremely challenging to decide the optimal time to move to the transmissions of the next segment, and existing designs all resort to different heuristic ideas that might harm network throughput. To address this problem, we propose \emph{SlideOR}, a new protocol to encode source packets in overlapping sliding windows such that coded packets from one window position may be useful towards decoding the source packets inside another window position. Through extensive simulations, we show that \emph{SlideOR} outperforms the existing solutions and is amenable to much simpler implementation than solutions with complicated scheduling among multiple segments.

On analyzing and improving COPE performance

Abstract: COPE is a new architecture for unicasts in wireless mesh networks that employs opportunistic network coding to improve total throughput. Katti et al. showed through experiments that this system significantly improves the throughput of wireless networks with UDP traffic, and several attempts have been made to analyze the COPE performance. However, they are not completely satisfactory. In this paper, we give a new analysis of COPE, and argue that the key to COPE's success lies in the interaction between COPE and the MAC protocol. The local fairness enforced by the MAC protocol among competing nodes play an important role here. Based on the analysis, we also propose a simple modification to the COPE system that can further improve the network throughput.

Method and system for dynamic information exchange on location aware mesh network devices

Abstract: A method and system for dynamic information exchange on mesh network devices. The dynamic information exchange includes allowing a mesh network device to communicate location information with a network device at pre-determined physical location and invite social contacts of the mesh network device to come to the pre-determined physical location. The network device sends various types of electronic messages (e.g., text message, e-mail, etc.) on a mesh network and/or a non-mesh communications network (e.g., the Internet, etc.) and to social networking sites. The dynamic information exchange also includes exchanging plural activity messages including a security identification authorization message for allowing access to a secure area, a building management message for automatically and dynamically managing heating, ventilation and/or air conditioning (HVAC) and/or an emergency location message for providing three-dimensional (3D) emergency location information.

Multicast Message Retransmission

Abstract: In one implementation, a method of distributing a multicast message in a wireless mesh network includes receiving a multicast message from a parent node of an intermediate node The method includes transmitting the multicast message to child nodes of the intermediate node The method includes storing the multicast message in a cache at the intermediate node The method includes intercepting an acknowledgement message from each acknowledging child node within an acknowledging subset of less than all of the child nodes The method includes accessing information indicating a population of the child nodes to which the multicast message transmission was directed The method includes comparing the acknowledging subset of the child nodes with the population of the child nodes The method includes identifying a non-acknowledging subset of less than all of the child nodes The method includes retransmitting the multicast message to the non-acknowledging subset of the child nodes

Mitigating selective forwarding attacks with a channel-aware approach in WMNS

Abstract: In this paper, we consider a special case of denial of service (DoS) attack in wireless mesh networks (WMNs) known as selective forwarding attack (a.k.a gray hole attacks). With such an attack, a misbehaving mesh router just forwards a subset of the packets it receives but drops the others. While most of the existing studies on selective forwarding attacks focus on attack detection under the assumption of an error-free wireless channel, we consider a more practical and challenging scenario that packet dropping may be due to an attack, or normal loss events such as medium access collision or bad channel quality. Specifically, we develop a channel aware detection (CAD) algorithm that can effectively identify the selective forwarding misbehavior from the normal channel losses. The CAD algorithm is based on two strategies, channel estimation and traffic monitoring. If the monitored loss rate at certain hops exceeds the estimated normal loss rate, those nodes involved will be identified as attackers. Moreover, we carry out analytical studies to determine the optimal detection thresholds that minimize the summation of false alarm and missed detection probabilities. We also compare our CAD approach with some existing solutions, through extensive computer simulations, to demonstrate the efficiency of discriminating selective forwarding attacks from normal channel losses.

Seamless handoff scheme for multi-radio wireless mesh network

Abstract: A mobile device communicates with a first mesh access point (AP) via a first radio frequency (RF) interface of the mobile device over a first wireless connection, where the first mesh AP is one of mesh APs of a first mesh cell of the wireless mesh network. It is detected that signal quality of the first wireless connection drops below a predetermined threshold as the mobile device moves from the first mesh cell towards a second mesh cell. In response to the detection, it is established via a second RF interface of the mobile device a second wireless connection with a second mesh AP of a second mesh cell of the wireless mesh network, while concurrently maintaining the first wireless connection with the first mesh AP via the first RF interface.

Genetic Algorithms for Efficient Placement of Router Nodes in Wireless Mesh Networks

Abstract: In Wireless Mesh Networks (WMNs) the meshing architecture, consisting of a grid of mesh routers, provides connectivity services to different mesh client nodes. The good performance and operability of WMNs largely depends on placement of mesh routers nodes in the geographical area to achieve network connectivity and stability. Thus, finding optimal or near-optimal mesh router nodes placement is crucial to such networks. In this work we propose and evaluate Genetic Algorithms (GAs) for near-optimally solving the problem. In our approach we seek a two-fold optimization, namely, the maximization of the size of the giant component in the network and that of user coverage. The size of the giant component is considered here as a criteria for measuring network connectivity. GAs explore the solution space by means of a population of individuals, which are evaluated, selected, crossed and mutated to reproduce new individuals of better quality. The fitness of individuals is measured with respect to network connectivity and user coverage being the former a primary objective and the later a secondary one. Several genetic operators have been considered in implementing GAs in order to find the configuration that works best for the problem. We have experimentally evaluated the proposed GAs using a benchmark of generated instances varying from small to large size. In order to evaluate the quality of achieved solutions for different possible client distributions, instances have been generated using different distributions of mesh clients (Uniform, Normal, Exponential and Weibull). The experimental results showed the efficiency of the GAs for computing high quality solutions of mesh router nodes placement in WMNs.

Wireless tracking system and method for backhaul of information

Abstract: The present invention provides a solution to backhauling health information The present invention utilizes a mesh network to backhaul the health information The system includes a plurality of first tags, a mesh network, and an information engine Each of the tags represents a first object The mesh network preferably includes a plurality of plug-in sensors located within the facility At least one node in the mesh network operates as healthcare device The information engine is in communication with the mesh network and determines a position location of the healthcare device and an operation of the healthcare device

Method and apparatus for engaging in a service or activity using an ad-hoc mesh network

Abstract: An approach is provided for discovering a local service over an ad-hoc mesh network. A local service is discovered sending an anonymous flooding message including a query over the ad-hoc mesh network. A wireless node replies to the flooding message over the ad-hoc mesh network with a pointer or data related to the discovered local service.

A novel soil measuring wireless sensor network

Abstract: Emerging technologies have made low-power and low-cost wireless sensor networks feasible. This paper presents a hierarchical wireless sensor network for measuring soil parameters such as temperature and humidity. Specifically, we designed sensor nodes that are placed completely underground and are used to collect soil measurements. These nodes use their radios to deliver the collected measurements to one of multiple relay nodes located above ground. In turn, relay nodes that are capable of long-range communications forward the data collected from the network's sensor nodes to a base node, which is connected to a workstation. The proposed hierarchical wireless sensor network uses a probabilistic communication protocol to achieve a very low duty cycle and hence a long life-time for soil monitoring applications.

Internet usage and performance analysis of a rural wireless network in Macha, Zambia

Abstract: There have been a number of rural wireless networks providing Internet access over the last decade but little is known about how the Internet is being used, how these networks perform and whether they follow similar trends when compared with Internet usage patterns in developed regions. We analyse a set of network traces from the Linknet wireless network in Zambia, which provides Internet access to approximately 300 residents of a rural village using a satellite link and a combination of point-to-point links, hotspots and wireless mesh networks. Our analysis reveals largely web-based traffic as opposed to the peer-to-peer traffic dominance that one finds in urban areas. Social networking sites receive the most hits, and large file downloads from operating system repositories contribute the most to the bandwidth consumption. A number of network pathologies in the gateway as well as the wireless mesh network are also analysed and a set of recommendations conclude the work.

Enabling Efficient Peer-to-Peer Resource Sharing in Wireless Mesh Networks

Abstract: Wireless mesh networks are a promising area for the deployment of new wireless communication and networking technologies. In this paper, we address the problem of enabling effective peer-to-peer resource sharing in this type of networks. Starting from the well-known Chord protocol for resource sharing in wired networks, we propose a specialization that accounts for peculiar features of wireless mesh networks: namely, the availability of a wireless infrastructure, and the 1-hop broadcast nature of wireless communication, which bring to the notions of location awareness and MAC layer cross-layering. Through extensive packet-level simulations, we investigate the separate effects of location awareness and MAC layer cross-layering, and of their combination, on the performance of the P2P application. The combined protocol, MeshChord, reduces message overhead of as much as 40 percent with respect to the basic Chord design, while at the same time improving the information retrieval performance. Notably, differently from the basic Chord design, our proposed MeshChord specialization displays information retrieval performance resilient to the presence of both CBR and TCP background traffic. Overall, the results of our study suggest that MeshChord can be successfully utilized for implementing file/resource sharing applications in wireless mesh networks.