Wireless Local Area Network

Abstract—In this paper, inkjet-printed UHF and microwave cir-cuits fabricated on paper substrates are investigated for the first time as an approach that aims for a system-level solution for fast and ultra-low-cost mass production. First, the RF characteristics of the paper substrate are ...

With the rapid development and wide deployment of wireless Local Area Networks (WLANs), WLAN-based po- sitioning system employing signal-strength-based technique has become an attractive solution for location estimation in indoor environment. In recent years, a number of such systems has been presented, and most of the systems use the common Nearest Neighbor in Signal Space (NNSS) algorithm. In this paper,

The widespread proliferation of wireless networks (WLAN) has opened up new paradigms of security policy management in enterprise networks. To enforce the organizational security policies in wireless local area networks (WLANs), it is required to protect the network resources from unauthorized access. In WLAN security policy management, the standard IP based access control mechanisms are not sufficient to meet the organizational requirements due to its dynamic topology characteristics. In such dynamic network environments, the role-based access control (RBAC) mechanisms can be deployed to strengthen the security perimeter over the network resources. Further, there is a need to incorporate time and location dependent constraints in the access control models. In this paper, we propose a WLAN security management system which supports a spatio-temporal RBAC (STRBAC) model. The system stems from logical partitioning of the WLAN topology into various security policy zones. It includes a Global Policy Server (GPS) that formalizes the organizational access policies and determines the high level policy configurations for different policy zones; a Central Authentication & Role Server (CARS) which authenticates the users (or nodes) and the access points (AP) in various zones and also assigns appropriate roles to the users. Each policy zone consists of an Wireless Policy Zone Controller (WPZCon) that co-ordinates with a dedicated Local Role Server (LRS) to extract the low level access configurations corresponding to the zone access points. We also propose a formal spatio-temporal RBAC (STRBAC) model to represent the security policies formally.

Rapidly growing 802.11 wireless local area networks continue to gain popularity in business and computer industry. This growing popularity and usage also caused many improvements on both physical layer and security mechanisms. In this study we investigated the performance of wireless local area networks (WLANs) and security mechanisms available for WLANs. These security mechanisms are wired equivalent privacy (WEP), Wi-Fi

The aim of this paper is to characterize the behavior of the UDP transport protocol, mainly in terms of throughput and average delay, over an IEEE 802.11b compliant wireless local area network (WLAN) from an experimental approach. Although performance evaluation of these kinds of LAN is being extensively discussed in the current literature, most of these studies are analytical or simulation-based and they do not consider the influence of channel impairments or link quality over network throughput. After an exhaustive measurement campaign, different performance parameters such as throughput, goodput, effective goodput, frame error rate, IT loss rate, delay and jitter have been obtained. This could be a preliminary analysis of the behavior of real-time traffic over WLAN infrastructures, such as streaming audio and voice transmission, services that are expected to undergo substantial growth in the coming years. All these studies and results have been developed in the context of the WINE (Wireless Internet Networks) project belonging to the framework of the Information Society Technologies (IST) programme, addressed to enhancing the performance of TCP/IP protocol over WLAN such as IEEE 802.11, Bluetooth and HIPERLAN/2

For the past ten years, heterogeneous networks wired and wireless had tended to integrate seamlessly, offering
effective and reliable service for medical operations. One of the problems encountered by network practitioners is the seamless integration of network components into healthcare delivery. As a multiplexing hospital model, the implementation certainly presents some challenges. The major technical and performance issues involve are as following. The operating parameters should keep aligned to the Quality of Service (QoS) requirement throughout simulation. Bandwidth utilisation of wireless networking is a challenging issue for real-time multimedia transmission. IEEE 802.11 provides relatively lower data rate than wired networks, thus the developer tends to adopt a more compromised solution: either reduce the file size or compress the image packets. Communication performance that varies constantly with the impact of signal strength, traffic load and interference. As stated radio signal senses as a curve and attenuates greatly while metallic object and
microwave exist within the active range. To ensure devices do not interfere with other electronic equipments (e.g. heart monitors), assert wireless spectrum has to be managed appropriately. This research paper aims to develop a generic hospital network scenarios using Wireless Local Area Network (WLAN) over OPNET Simulation, to evaluate the performance of the integrated network scenario for Intensive Care Units (ICU).  This research makes use of computer simulation and discusses various aspects of the network design, so as to discover the performance behaviour pertaining to effect of traffic type, traffic load and network size. In the ICU scenario, the performance of video conference degrades with network size, thus, a QoS-enabled device is recommended to reduce the packet delay and data loss. IEEE 802.11a suits in hospital environment because it mitigates interference on the 2.4GHz band where most wireless devices operate. Experiment examines the effect of signal strength in WLAN. It is convinced that -88dBm is the best signal strength threshold. Although 802.11a generates slightly lower throughput than 802.11g, this issues can be addressed by placing more APs in the service area. It is convinced that 802.11a suits the hospital environments, because it mitigates interference on the popular 2.4GHz band where most wireless devices operate. It is important for medical devices which require future upgrade and Bluetooth deployment.

This letter presents a compact interdigital stripline bandpass filter embedded in low temperature cofired ceramic for 5-GHz wireless LAN applications, including design, simulation, fabrication, and measurements. The filter measures 8 mm×7 mm×1.1 mm and exhibits an insertion loss of 3.6 dB, a return loss of 20 dB, and a 212-MHz passband with the midband frequency at 5.28 GHz. The filter is highly reproducible with good tolerance. A low noise amplifier (LNA) built on the top of the LTCC substrate with an embedded filter has the same bandwidth and midband frequency as those of the filter. Using this filter and an integrated chip, a small RF front-end receiver has been achieved.

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.

This paper presents the design of an efficient low complexity residual phase tracking algorithm for Orthogonal Frequency Division Multiplexing (OFDM) based Wireless Local Area Network receivers. In this paper the focus is on mitigation of the residual carrier frequency synchronization offset and sampling frequency offset. We propose a novel algorithm that uses piecewise linear approximation to estimate the com- plex

We evaluated the use of a true single phase clocking (TSPC) circuit as a high-frequency divider-by-3 circuit. This divider consists of two TSPC D-flip-flops (D-FFs) with NOR gate logic circuitry. To achieve high-speed operations as well as downsize the circuit, the NOR functions are implemented into the TSPC D-FF. We designed the divider using a 0.18-"m RF CMOS process; the

Summary Wireless Local Area Networks (WLANs) are cost effective and desirable gateways to mobile computing. They allow computers to be mobile, cable less and communicate with speeds close to the speeds of wired LANs. These features came with expensive price to ...

Summary Wireless Local Area Networks (WLANs) are cost effective and desirable gateways to mobile computing. They allow computers to be mobile, cable less and communicate with speeds close to the speeds of wired LANs. These features came with expensive price to ...

Delay-sensitive video transmission over IEEE 802.11 wireless local area networks (WLANs) is analyzed in a cross-layer optimization framework. The effect of delay constraint on the quality of received packets is studied by analyzing “expired-time packet discard rate”. Three analytical models are examined and it is shown that M/M/1 model is quite an adequate model for analyzing delay-limited applications such as