Showing papers on "Wireless WAN published in 2006"

Hot topic: physical-layer network coding

Abstract: A main distinguishing feature of a wireless network compared with a wired network is its broadcast nature, in which the signal transmitted by a node may reach several other nodes, and a node may receive signals from several other nodes simultaneously. Rather than a blessing, this feature is treated more as an interference-inducing nuisance in most wireless networks today (e.g., IEEE 802.11). The goal of this paper is to show how the concept of network coding can be applied at the physical layer to turn the broadcast property into a capacity-boosting advantage in wireless ad hoc networks. Specifically, we propose a physical-layer network coding (PNC) scheme to coordinate transmissions among nodes. In contrast to "straightforward" network coding which performs coding arithmetic on digital bit streams after they have been received, PNC makes use of the additive nature of simultaneously arriving electromagnetic (EM) waves for equivalent coding operation. PNC can yield higher capacity than straight-forward network coding when applied to wireless networks. We believe this is a first paper that ventures into EM-wave-based network coding at the physical layer and demonstrates its potential for boosting network capacity. PNC opens up a whole new research area because of its implications and new design requirements for the physical, MAC, and network layers of ad hoc wireless stations. The resolution of the many outstanding but interesting issues in PNC may lead to a revolutionary new paradigm for wireless ad hoc networking.

XORs in the air: practical wireless network coding

Abstract: This paper proposes COPE, a new architecture for wireless mesh networks. In addition to forwarding packets, routers mix (i.e., code) packets from different sources to increase the information content of each transmission. We show that intelligently mixing packets increases network throughput. Our design is rooted in the theory of network coding. Prior work on network coding is mainly theoretical and focuses on multicast traffic. This paper aims to bridge theory with practice; it addresses the common case of unicast traffic, dynamic and potentially bursty flows, and practical issues facing the integration of network coding in the current network stack. We evaluate our design on a 20-node wireless network, and discuss the results of the first testbed deployment of wireless network coding. The results show that COPE largely increases network throughput. The gains vary from a few percent to several folds depending on the traffic pattern, congestion level, and transport protocol.

Node clustering in wireless sensor networks: recent developments and deployment challenges

Abstract: The large-scale deployment of wireless sensor networks (WSNs) and the need for data aggregation necessitate efficient organization of the network topology for the purpose of balancing the load and prolonging the network lifetime. Clustering has proven to be an effective approach for organizing the network into a connected hierarchy. In this article, we highlight the challenges in clustering a WSN, discuss the design rationale of the different clustering approaches, and classify the proposed approaches based on their objectives and design principles. We further discuss several key issues that affect the practical deployment of clustering techniques in sensor network applications.

Radio Network Planning and Optimisation for Umts

Abstract: From the Publisher: Radio Network Planning and Optimisation for UMTS comprehensively explains how to dimension, plan and optimise UMTS networks. It introduces the properties of the spread spectrum system and provides a general overview of the physical layer of UTRA FDD. The radio network planning process for WCDMA is clearly presented and detailed information on how to dimension, plan and rollout a 3G network, both theoretically and practically is provided. This valuable text examines current and future radio network management issues and their impact on network performance as well as the relevant capacity and coverage enhancement methods. Authoritative and instructive, this text will have instant appeal to wireless operators and network and terminal manufacturers. It will also be essential reading for university students, frequency regulation bodies and everyone interested in radio network planning and optimisation, especially RF network systems engineering professionals.

Medium Access Control protocols for ad hoc wireless networks: A survey

Abstract: Studies of ad hoc wireless networks are a relatively new field gaining more popularity for various new applications. In these networks, the Medium Access Control (MAC) protocols are responsible for coordinating the access from active nodes. These protocols are of significant importance since the wireless communication channel is inherently prone to errors and unique problems such as the hidden-terminal problem, the exposed-terminal problem, and signal fading effects. Although a lot of research has been conducted on MAC protocols, the various issues involved have mostly been presented in isolation of each other. We therefore make an attempt to present a comprehensive survey of major schemes, integrating various related issues and challenges with a view to providing a big-picture outlook to this vast area. We present a classification of MAC protocols and their brief description, based on their operating principles and underlying features. In conclusion, we present a brief summary of key ideas and a general direction for future work.

Wireless diversity through network coding

Abstract: This paper investigates the diversity gain offered by implementing network coding (R. Ahlswede et al., 2000) over wireless communication links. The network coding algorithm is applied to both a wireless network containing a distributed antenna system (DAS) as well as one that supports user cooperation between users. The results show that network-coded DAS leads to better diversity performance as compared to conventional DAS, at a lower hardware cost and higher spectral efficiency. In the case of user cooperation, network coding yields additional diversity, especially when there are multiple users

MIMO-OFDM wireless systems: basics, perspectives, and challenges

Abstract: Multiple-input multiple-output (MIMO) wireless technology in combination with orthogonal frequency division multiplexing (MIMO-OFDM) is an attractive air-interface solution for next-generation wireless local area networks (WLANs), wireless metropolitan area networks (WMANs), and fourth-generation mobile cellular wireless systems. This article provides an overview of the basics of MIMO-OFDM technology and focuses on space-frequency signaling, receiver design, multiuser systems, and hardware implementation aspects. We conclude with a discussion of relevant open areas for further research

CRAWDAD: a community resource for archiving wireless data at Dartmouth

Abstract: Wireless network researchers are seriously starved for data about how real users, applications, and devices use real networks under real network conditions. CRAWDAD, a Community Resource for Archiving Wireless Data at Dartmouth, is a new NSF-funded project to build a wireless network data archive for the research community. We host wireless data, and provide tools and documents to make it easy to collect and use wireless network data. We hope that this resource will help researchers identify and evaluate real and interesting problems in mobile and pervasive computing. This report outlines the CRAWDAD project, the kick-off work-shop that was held at MobiCom 2005, and the latest news. how real users, applications, and devices use real networks under real conditions, and how mobile users actually move about. This data helps us to identify and understand the real problems, to evaluate possible solutions, and to evaluate new applications and services.

Rf interconnected hvac system and security system

Abstract: An interconnected wireless HVAC (heating, ventilation, air conditioning) system and wireless security system, which are interconnected and communicate with each other through the use of a common wireless technology, including the same selected frequency, modulation and a set of common protocols. The Wireless HVAC system includes wireless thermostats, which can communicate with and control both the HVAC system and the security system, and the wireless security system includes wireless controls or keypads, which can communicate with and control both the security system and the HVAC system. The universal wireless infrastructure can be expanded to provide communication or control of additional user or manufacturer installed wireless devices or systems through the universal wireless home infrastructure.

An energy-efficient ant-based routing algorithm for wireless sensor networks

Abstract: Wireless Sensor Networks are characterized by having specific requirements such as limited energy availability, low memory and reduced processing power. On the other hand, these networks have enormous potential applicability, e.g., habitat monitoring, medical care, military surveillance or traffic control. Many protocols have been developed for Wireless Sensor Networks that try to overcome the constraints that characterize this type of networks. Ant-based routing protocols can add a significant contribution to assist in the maximisation of the network lifetime, but this is only possible by means of an adaptable and balanced algorithm that takes into account the Wireless Sensor Networks main restrictions. This paper presents a new Wireless Sensor Network routing protocol, which is based on the Ant Colony Optimization metaheuristic. The protocol was studied by simulation for several Wireless Sensor Network scenarios and the results clearly show that it minimises communication load and maximises energy savings.

Methods and devices for interworking of wireless wide area networks and wireless local area networks or wireless personal area networks

Abstract: Embodiments describe registration in a wireless communication system. A method includes wirelessly transmitting over a WWAN a first registration message from a mobile device, wirelessly transmitting through the WWAN a second registration message to a WLAN access point and receiving at the mobile device access through the WLAN access point. According to another embodiment is a method for constructing a self-configuring ad-hoc network. The method can include receiving a GPS coordinate from a WWAN channel node at a management system and creating an initial topography based at least in part on the GPS coordinate to achieve a network connectivity with diverse routes between a plurality of nodes.

Peer-to-peer communication in ad hoc wireless network

Abstract: For a peer-to-peer call in an ad hoc wireless network, a wireless device performs discovery of a target wireless device, performs authentication of the target wireless device and generates a session key (e.g., using a pre-shared key or a certificate provisioned on the wireless device), forms an ad hoc wireless network with the target wireless device, and communicates peer-to-peer with the target wireless device via the ad hoc wireless network. The wireless device may perform discovery with a list of identifiers for wireless devices designated to communicate with this wireless device. The wireless device may derive a service set identifier (SSID) used to identify the ad hoc wireless network based on its user-specific identifier (e.g., its phone number) and/or a user-specific identifier for the target wireless device. The wireless device may also performs IP address discovery using the user-specific identifier for the target wireless device.

Wireless network with adaptive autonomous location push

Abstract: A method of providing location-based services includes transmitting a first location criterion from a wireless network server to a wireless device. The method also includes evaluating whether a physical location of the wireless device satisfies the first location criterion. The process of evaluating is performed in part using the wireless device. When the first location criteria is satisfied, the method further includes transmitting an indication from the wireless device to the server that the first location criterion has been satisfied.

A Client-Driven Approach for Channel Management in Wireless LANs

Abstract: We propose an efficient client-based approach for channel management (channel assignment and load balancing) in 802.11-based WLANs that lead to better usage of the wireless spectrum. This approach is based on a “conflict set coloring” formulation that jointly performs load balancing along with channel assignment. Such a formulation has a number of advantages. First, it explicitly captures interference effects at clients. Next, it intrinsically exposes opportunities for better channel re-use. Finally, algorithms based on this formulation do not depend on specific physical RF models and hence can be applied efficiently to a wide-range of in-building as well as outdoor scenarios. We have performed extensive packet-level simulations and measurements on a deployed wireless testbed of 70 APs to validate the performance of our proposed algorithms. We show that in addition to single network scenarios, the conflict set coloring formulation is well suited for channel assignment where multiple wireless networks share and contend for spectrum in the same physical space. Our results over a wide range of both simulated topologies and in-building testbed experiments indicate that our approach improves application level performance at the clients by upto three times (and atleast 50%) in comparison to current best-known techniques.

Signal threshold adaptation for vertical handoff in heterogeneous wireless networks

Abstract: The convergence of heterogeneous wireless access technologies has been envisioned to characterize the next generation wireless networks. In such converged systems, the seamless and efficient handoff between different access technologies (vertical handoff) is essential and remains a challenging problem. The heterogeneous co-existence of access technologies with largely different characteristics results in handoff asymmetry that differs from the traditional intra-network handoff (horizontal handoff) problem. In the case where one network is preferred, the vertical handoff decision should be carefully executed, based on the wireless channel state, network layer characteristics, as well as application requirements. In this paper, we study the performance of vertical handoff using the integration of 3G cellular and wireless local area networks as an example. In particular, we investigate the effect of an application-based signal strength threshold on an adaptive preferred-network lifetime-based handoff strategy, in terms of the signalling load, available bandwidth, and packet delay for an inter-network roaming mobile. We present an analytical framework to evaluate the converged system performance, which is validated by computer simulation. We show how the proposed analytical model can be used to provide design guidelines for the optimization of vertical handoff in the next generation integrated wireless networks.

System and Method for Determining Geographic Location of Wireless Computing Devices

Abstract: System for enabling a wireless computing device to determine its position includes a server with a database of identification and positional information about wireless beacons and a wireless computing device arranged to wirelessly communicate using the Internet with the server. The server determines the geographic location of the wireless computing device upon receiving data from the wireless computing device relating to reception of signals by the wireless computing device from at least one wireless beacon and analysis of the signals in light of the information contained in the database of the server. The server applies a calculation algorithm which determines the geographic location of the wireless computing device upon input of identification and signal strength information about the wireless beacon(s) derived from the received signals.

Emerging standards for wireless mesh technology

Abstract: Wireless mesh networking is a promising technology for numerous applications which appeals especially to those applications that cannot be directly supported by other wireless technologies. The commercial success of Wi-Fi and the advances in many wireless technologies have in part stimulated the development of wireless mesh networks. The persistent driving force, however, comes from the envisioned advantages of wireless mesh techniques themselves, including extended coverage, robustness, self-configuration, easy maintenance, and low cost. This article presents an overview of this emerging technology, focusing on the technical merits and related standards activities of IEEE and ZigBee that are actively applying the concept of multi-hop mesh techniques in the field of wireless networking technologies, ranging from personal area networks (PANs) to metropolitan area networks (MANs)

A Network Coding Approach to Energy Efficient Broadcasting: From Theory to Practice

Abstract: We show that network coding allows to realize significant energy savings in a wireless ad-hoc network, when each node of the network is a source that wants to transmit information to all other nodes. Energy efficiency directly affects battery life and thus is a critical design parameter for wireless ad-hoc networks. We propose an implementable method for performing network coding in such a setting. We analyze theoretical cases in detail, and use the insights gained to propose a practical, fully distributed method for realistic wireless adhoc scenarios. We address practical issues such as setting the forwarding factor, managing generations, impact of transmission range and mobility. We use theoretical analysis and packet level simulation.

Toward a theory of in-network computation in wireless sensor networks

Abstract: Sensor networks are not just data networks with sensors being the sources of data. Rather, they are often developed and deployed for a specific application, and the entire network operation is accordingly geared toward satisfying this application. For overall system efficiency, it may be necessary for nodes to perform computations on data, as opposed to simply originating or forwarding data. Thus, the entire network can be viewed as performing an application-specific distributed computation. The topic of this article is to survey some lines of research that may be useful in developing a theory of in-network computation, which aims to elucidate how a wireless sensor network should efficiently perform such distributed computation. We review several existing approaches to computation problems in network settings, with a particular emphasis on the communication aspect of computation. We begin by studying the basic two-party communication complexity model and how to optimally compute functions of distributed inputs in this setting. We proceed to larger multihop networks, and study how block computation and function structure can be exploited to provide greater computational throughput. We then consider distributed computation problems in networks subject to noise. Finally, we review some randomized gossip-based approaches to computing aggregate functions in networks. These are diverse approaches spanning many different research communities, but together may find a role in the development of a more substantial theoretical foundation for sensor networks.

Provisioning of wireless connectivity for devices using nfc

Abstract: The claimed subject matter provides a system and/or a method that facilitates connecting a wireless device to a secure network. A device can establish a near field communication link with a verified device on a network, wherein the near field communication link can be a secure and/or encrypted link to provision the device without compromising security constraints within the network. An installation component can invoke the transfer of provisioning data to the network via the near field communication link to secure a wireless connection for the device to the network.

An Adaptive Strategy for Quality-Based Data Reduction in Wireless Sensor Networks

Abstract: Wireless sensor networks allow fine-grained observations of real-world phenomena. However, providing constant measurement updates incurs high communication costs for each individual node, resulting in increased energy depletion in the network. Data reduction strategies aim at reducing the amount of data sent by each node, for example by predicting the measured values both at the source and the sink node, thus only requiring nodes to send the readings that deviate from the prediction. While effectively reducing power consumption, such techniques so far needed to rely on a-priori knowledge to correctly model the expected values. Our approach instead employs an algorithm that requires no prior modeling, allowing nodes to work independently and without using global model parameters. Using the LeastMean-Square (LMS) adaptive algorithm on a publicly available, real-world (office environment) temperature data set, we have been able to achieve up to 92% communication reduction while maintaining a minimal accuracy of 0.5 degree Celsius.

Multimedia network appliances for security and surveillance applications

Abstract: Network appliances for use in combination with a network based full service, multi-media surveillance system provide a wide range of monitoring techniques utilizing digital network architecture. The appliances may be connected to the surveillance system for transmitting event data, video and/or image monitoring information, audio signals and other data over significant distances using digital data transmission over networks such as a local area network (LAN), a wireless LAN (WLAN), a wide area network such as the Internet for other networks, permitting remote manual and/or automatic assessment and response. The wireless LAN connectivity permits local distribution of audio, video and image data with relatively high bandwidth without requirement of a license and without relying on a common carrier and the fees associated therewith. The surveillance system may be interfaced with a WAN (wide area network) such as frame relay or the Internet for providing a worldwide, low cost surveillance system with virtually unlimited geographic application. Multiple sensors and appliances may be accommodated, as required. The topology of the network will be established by the geographic situation of the specific installation. Appropriate firewalls may be set up as desired to protect unauthorized access to the system or collected data. The server based system permits a security provider to have access to the appliance, related sensor and surveillance data or to configure or reconfigure the system from any station on the Intranet or Internet.

On the use of wireless networks at low level of factory automation systems

Abstract: Wireless communication systems are rapidly becoming a viable solution for employment at the lowest level of factory automation systems, usually referred to as either "device" or "field" level, where the requested performance may be rather critical in terms of both transmission time and reliability. In this paper, we deal with the use of wireless networks at the device level. Specifically, after an analysis of the communication requirements, we introduce a general profile of a wireless fieldbus. Both the physical and data link layers are taken directly from existing wireless local area networks and wireless personal area networks standards, whereas the application layer is derived from the most popular wired fieldbuses. We discuss implementation issues related to two models of application layer protocols and present performance results obtained through numerical simulations. We also address some important aspects related to data security and power consumption.

Controlling wireless access to a network

Abstract: Various methods and apparatus are described in for a wireless access point. The wireless access point allows access to a wireless LAN that has two or more service set identifiers (SSIDs). At least one of the SSIDs is associated with a public wireless LAN. The wireless access point implements a segmentation policy that 1 ) provides unimpeded access to a Wide Area network through the public wireless LAN based on a first type of application or a first type of device detected by the wireless access point and 2) restricts access to the Wide Area network through the public wireless LAN by requiring an authorization check to access the Wide Area network based on detecting a second type of application.

Smart Gossip: An Adaptive Gossip-based Broadcasting Service for Sensor Networks

Abstract: A network-wide broadcast service is often used for information dissemination in sensor networks. Sensor networks are typically energy-constrained and prone to failures. In view of these constraints, the broadcast service should minimize energy consumption by reducing redundant transmissions, and be tolerant to frequent node and link failures. We propose "Smart Gossip", a probabilistic protocol that offers a broadcast service with low overheads. Smart gossip automatically and dynamically adapts transmission probabilities based on the underlying network topology. The protocol is capable of coping with wireless losses and unpredictable node failures that affect network connectivity over time. The resulting protocol is completely decentralized. We present thorough experimental results to evaluate our "Smart Gossip" proposal, and demonstrate its benefits over existing protocols.

Public Key Based Cryptoschemes for Data Concealment in Wireless Sensor Networks

Abstract: In-network data aggregation is a popular technique for reducing the energy consumption tied to data transmission in a multi-hop wireless sensor network. However, data aggregation in untrusted or even hostile environments becomes problematic when end-to-end privacy between sensors and the sink is desired. In this paper we revisit and investigate the applicability of additively homomorphic public-key encryption algorithms for certain classes of wireless sensor networks. Finally, we provide recommendations for selecting the most suitable public key schemes for different topologies and wireless sensor network scenarios.

Hybrid power line wireless communication network

Abstract: A hybrid power line wireless communication system may include an access controller and plurality of communication nodes that each may include a wireless access point coupled to a power line communication device. The wireless access points may provide wireless broadband communications to one or more user devices while the power line communication devices may provide low voltage power line broadband communications. The access controller remotely manages the wireless access points by sending control messages to the communication nodes. Control messages may traverse a power line, a non-power line medium, and/or a wireless medium. Control messages may include information relating to encryption parameters, transmission power levels, communication channels, access control, and other such parameters.

Dynamically optimized smart antenna system

Abstract: A wireless communications network includes a plurality of wireless devices equipped with direction-agile antenna systems to allow the wireless devices to establish and maintain wireless data links with each other.

Enhancing the security of corporate Wi-Fi networks using DAIR

Abstract: We present a framework for monitoring enterprise wireless networks using desktop infrastructure. The framework is called DAIR, which is short for Dense Array of Inexpensive Radios. We demonstrate that the DAIR framework is useful for detecting rogue wireless devices (e.g., access points) attached to corporate networks, as well as for detecting Denial of Service attacks on Wi-Fi networks.Prior proposals in this area include monitoring the network via a combination of access points (APs), mobile clients, and dedicated sensor nodes. We show that a dense deployment of sensors is necessary to effectively monitor Wi-Fi networks for certain types of threats, and one can not accomplish this using access points alone. An ordinary, single-radio AP can not monitor multiple channels effectively, without adversely impacting the associated clients. Moreover, we show that a typical deployment of access points is not sufficiently dense to detect the presence of rogue wireless devices. Due to power constraints, mobile devices can provide only limited assistance in monitoring wireless networks. Deploying a dense array of dedicated sensor nodes is an expensive proposition.Our solution is based on two simple observations. First, in most enterprise environments, one finds plenty of desktop machines with good wired connectivity, and spare CPU and disk resources. Second, inexpensive USB-based wireless adapters are commonly available. By attaching these adapters to desktop machines, and dedicating the adapters to the task of monitoring the wireless network, we create a low cost management infrastructure.

Mobile router device

Abstract: A wireless mobile router ( 140 ) includes wireless network interfaces ( 202 ) and ( 218 ) attached to a network controller ( 142 ). The wireless network interface ( 202 ) communicates with a cellular network ( 110 ) to access cellular network services. The wireless network interface ( 218 ) and the network controller ( 142 ) comprise a WLAN ( 170 ) or PAN ( 180 ) network router hosting a plurality of client devices. Each client device may access a wide area network, WAN over the cellular network. The wireless mobile router ( 140 ) is configured to exchange various cellular network signals with various WLAN and PAN networks. The wireless mobile router ( 140 ) is particularly suitable for use in a vehicle or at locations where WAN access is not readily available.