Broadband Local Area Network Research Articles

High Isolation and Compact Microstrip Diplexer for Broadband and WLAN Application

A high isolation and compact microstrip diplexer for broadband and wireless local area network (WLAN) application is proposed in this paper. It is achieved by using the combination of a broadband bandpass filter (BPF) composed of one open stub and two short stubs of different size loaded in 50Ω feed lines. The tapped stub can not only generate two zeros to deepen the stopband, but also connect other BPF without deterioration of in-band performance. Hence, the compact diplexer combines two BPFs without extra junction matching network. The mutual loading effect approximately equivalent to a coupled resonator can create one zero at the passband edge to improve the isolation. The proposed microstrip diplexer is designed and fabricated, and it has a 1dB fractional bandwidths (FBW) of 60% at 3.5GHz for broadband channel and 3% at 5.8GHz for WLAN channel . The simulated and measured results are presented and good agreement is obtained.

A Compact Loop Type Antenna for Bluetooth, S-DMB, Wibro, WiMax, and WLAN Applications

This paper presents a novel compact loop type antenna for Bluetooth, satellite-digital multimedia broadcasting, wireless broadband, and wireless local-area network applications. The proposed antenna fed by a 50-Omega coaxial line occupies a compact volume of 26 times 8 times 3 mm3 . The bandwidth is 19.9% (2.26-2.76 GHz) and 45.6% (4.03-6.4 GHz) at S11< -10 dB and the measured maximum gain is 6.41 dBi at 5.35 GHz. The Microwave Studio simulation is employed for optimizing the design parameters, and the simulated results agree well agree with those of the measured one.

Design and characterization of single- and multiple-beam mm-wave circularly polarized substrate lens antennas for wireless communications

Single- and multiple-beam circularly polarized ellipsoidal substrate lenses suitable for millimeter-wave wireless communications have been designed, implemented, and experimentally characterized at 30 GHz. The lenses are made out of low-cost low-permittivity Rexolite material. The single-beam lens achieves a directivity of 25.9 dB, a front-to-back ratio of 30 dB, and an axial ratio of 0.5 dB is maintained within the main lobe. The measured impedance bandwidth is 12.5% within a SWR/spl les/1.8:1. The single-beam antenna is well suited for broad-band wireless point-to-point links. On the other hand, the multiple-beam lens launches 31 beams with a minimum 3-dB overlapping level among adjacent beams. The coverage of the lens antenna system has been optimized through the utilization of a hexagonal patch arrangement leading to a scan coverage of 45.4/spl deg/ with a maximum loss in directivity of 1.8 dB due to multiple reflections. The multiple-beam lens antenna is suitable for indoor point-to-multipoint wireless communications such as a broad-band local area network or as a switched beam smart antenna. During the proposed design process, some fundamental issues pertaining to substrate lens antennas are discussed and clarified. This includes the depolarization properties of the lenses, the effect of multiple internal reflections on the far-field patterns and the directivity, the nature of the far-field patterns, the estimation of the lens system F/B ratio, and the off-axis characteristics of ellipsoidal lenses.

Simple ASK transmitter using a 790 nm self-pulsating laser diode for local area networks

A simple amplitude shift keying (ASK) optical link is demonstrated by using a low-cost self-pulsating laser diode and an envelope detector for a low-cost broadband local area network. A link sensitivity of -22 dBm was achieved at 200 Mbit/s. Because the self-pulsation frequency can be tuned by the bias current, frequency division multiplexing can be simply implemented for multiuser applications. >

STARNET: A Multi-gigabit-per-second Optical LAN Utilizing a Passive WDM Star

We propose a new broad-band local area network, STARNET, based on a physical passive star topology. Over a single physical network, STARNET offers all users both a moderate-speed packet network and a high-speed WDM circuit interconnect. Based on these two data transport facilities, several topological and protocol solutions are available to the users. As a result, STARNET supports traffic of widely different speed and continuity characteristics. Each node of the network requires only two lasers and its structure facilitates the achievement of frequency stabilization for the whole network. An effort toward an experimental demonstration of a 3 Gb/s per node, FDDI-compatible (at the packet network level) STARNET is currently in progress at the Optical Communication Research Laboratory of Stanford University.

STARNET: a multi-gigabit-per-second optical LAN utilizing a passive WDM star

We propose a new broad-band local area network, STARNET, based on a physical passive star topology. Over a single physical network, STARNET offers all users both a moderate-speed packet network and a high-speed WDM circuit interconnect. Based on these two data transport facilities, several topological aDd protocol solutions are available to the users. As a result, STARNET supports traffic of widely different speed and continuity characteristics. Each node of the network requires only two lasers and its structure facilitates the achievement of frequency stabilization for the whole network. An effort toward an experimental demonstration of a 3 Gb/s per node, FDDI-compatible (at the packet network level) STARNET is currently in progress at the Optical Communication Research laboratory of Stanford University

Robot integration within computer-integrated manufacture

Increasingly robots form part of a complex automation scheme, dictating a requirement for robot control systems which can communicate beyond their local working environment. This paper explains how MAP Version 2·1 broadband local area network interfaces have been used to facilitate robot integration with computer-integrated manufacturing systems and describes integration methodologies which can find widespread application. To illustrate the principles involved a robot-based flexible assembly system has been constructed to assemble and test printed circuit boards. Each machine element of the flexible assembly system has been linked to a MAP backbone through the use of ‘OSI intelligent interfaces’ (or gateways). The interfaces incorporate INI COMMengines and were constructed at Loughborough University to achieve MAP to machine-specific protocol conversion and where appropriate to provide enhanced front-end processing facilities in the locality of machines. The paper also describes the features and use of an...

The Crossover Net LAN system using an intelligent head-end

The development of a multimedia broadband local area network (LAN) system named CrossoverNet using a intelligent head-end is presented. This head-end provides two-way digital/analog communication with dynamic channel exchange and network configuration control. Based on these functions, the head-end exchanges analog information in a manner similar to digital circuit exchange. Digital and analog information are transmitted separately over the same broadband cable and integrated in audiovisual protocol layers. To provide these facilities, a LAN architecture conforming to the Open Systems Interconnection (OSI) basic reference model is designed using broadband and CATV network technologies. The result, CrossoverNet, can control, operate, and manage a variety of audiovisual devices that are attached to it in a consistent manner. A prototype experiment illustrates the versatility of the system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Data communications within a health authority.

This paper describes the data communication network installed in four hospitals in the Hammersmith and Queeen Charlotte's Special Health Authority to support several hundred microcomputers, terminals and printers and several host systems, including the integrated computerized hospital information system which is currently under development. Broadband local area network and wide area network technologies have been employed to provide a flexible system, which is capable of being expanded to meet the increasing demand for data communications within the authority. The broadband networks are the first such installations in a health authority in Britain.

Analog Fiber Optic Communication By Pulse-Width Modulation

Characteristics of pulse-width modulation (PWM) were studied to provide an analog communication alternative to the predominantly digital techniques presently used in fiber optic links. Large analog signal dynamic range and high SNR, coupled with freedom from intermodulation, make PWM attractive for broadband local area network (LAN) applications, including future information-oriented offices and hospitals and automated factory floors. A simple video link was constructed using common laboratory equipment. The performance of the video link supports the PWM theory developed here and elsewhere. Analog transmission capability was experimentally demonstrated. SNR was limited only by the carrier noise, and no evidence of the intermodulation problem was observed.

Pulse width modulation for analog fiber-optic communications

The pulse width modulation (PWM) technique has been revisited and analyzed to evaluate its merits for application to analog signal transmission in fiber-optic links. Fourier analysis of the PWM signal reveals that it can be used as a vehicle to launch an analog signal onto optical fiber when a symmetrical natural sampling process is used. The SNR of the modulated signal depends on the timing jitter of the carrier pulses and a wide-band (45 MHz) SNR of 45 dB has been obtained with a commercially available multimode laser transmitter. A linear dynamic range of over 50 dB has been experimentally demonstrated. The full fiber bandwidth can be utilized by using a very high pulse carrier frequency, while a more popular pulse frequency modulation technique provides about a 10-MHz analog signal bandwidth when 1 km of multimode fiber is used in conjunction with a short wavelength (0.87 μm) LED transmitter. Analog transmission capability was experimentally demonstrated by constructing a simple video link using common laboratory equipment. The performance of the video link supports the PWM modulation theory developed here and elsewhere. The experimental results indicated that PWM is potentially very attractive for low-cost broad-band local area network (LAN) application, including future highly interactive offices, hospitals, and automated factory floors.

A simple file server for a terminal support network environment

Terminal Support Networks (TSNs) are becoming popular, particularly in the university environment, to interconnect microcomputer systems and also to use them as terminals to access mainframe computers. In such environments it seems attractive to share the disk space available on a large time sharing system. This paper describes the design and implementation of a file server which is simple to implement and user friendly. A broadband Local Area Network (LAN) provides the TSN environment. The main emphasis is on the communication aspects between the client and the file server, and the automatic recovery provided by the system after a system start up from a failure.

A Broadband Local Area Network

The IEEE 802 standard for local area network based on Carrier Sense Multiple-Access with Collision Detection (CSMA/CD) operates at a peak rate of 10 Mb/s on a cable of maximum length 2.5 km using baseband signaling. In many situations, larger channel rates are required over a much larger area. However, the efficiency of the CSMA/CD access method decreases rapidly if either the length of the cable is increased for a fixed bit rate or if the bit rate is increased for a fixed cable length. In this paper, we propose a broadband network for computer communications containing several CSMA/CD-type systems, each operating in a different frequency band. In addition, in order to have a wide area access, while minimizing the loss of performance associated with large collision delays, terminals in a small given geographical area are given one of the frequency bands for transmission. Two access protocols are developed. Using these schemes, it is possible to increase the channel throughput and the access area and to reduce the collision delay. We present a simplified analysis to quantify the improvement in performance using our schemes.

Envelope Detection of Binary VSB Data Signals

The performance of vestigial-sideband data transmission systems employing envelope detection is considered in the context of broad-band local area networks (BLAN's). General results for horizontal and vertical eye opening are presented and noise performance is assessed for three systems of particular interest. It is concluded that this data transmission scheme is suitable for BLAN's.

Distribution of Computer Functionality for Accelerator Control at the Brookhaven AGS

A set of physical and functional system components and their interconnection protocols have been established for all controls work at the AGS. Portions of these designs were tested as part of enhanced operation of the AGS as a source of polarized protons and additional segments will be implemented during the continuing construction efforts which are adding heavy ion capability to our facility. Included in our efforts are the following computer and control system elements: a broad band local area network, which embodies MODEMS; transmission systems and branch interface units; a hierarchical layer, which performs certain data base and watchdog/alarm functions; a group of work station processors (Apollo's) which perform the function of traditional minicomputer host(s) and a layer, which provides both real time control and standardization functions for accelerator devices and instrumentation. Data base and other accelerator functionality is assigned to the most correct level within our network for both real time performance, long-term utility, and orderly growth.

Correction to "Overview of a Broad-Band Local Area Network Protocol Architecture"

Correction to "Overview of a Broad-Band Local Area Network Protocol Architecture"

Interconnection of broadband local area networks

Interconnection of multiple broadband local area networks to form an integrated packet transport system presents several challenges. To take full advantage of broadband systems, assignment of nodes to channels must be dynamic, leading to the use of a flat address space. Combined with the desire to avoid reliance on a central server or complex routing in packet forwarders, this addressing scheme leads to adoption of a controlled flooding technique to “discover” the best path to a destination node. This discovery procedure sets up a path through internetwork forwarders for use by subsequent packets to the same destination. This paper describes the design and implementation of such a technique in Sytek's LocalNet(TM) systems along with several refinements which increase performance and keep the worst case load for route discovery below a few percent of network capacity.

Overview of a Broad-Band Local Area Network Protocol Architecture

The protocol architecture of a broad-band local area network (LAN) must consider a realm of issues ranging from user device requirements to the characteristics of the underlying broad-band cable medium. The primary environment for which these protocols are intended consists of a collection of multichannel broad-band local networks, connected by point-to-point links. This paper describes one example of a broad-band LAN protocol architecture, LocalNet ( <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TM</sup> Sytek Inc.). Particular attention is paid to those design decisions and practical considerations which were prompted by the intended environment.