86 research outputs found

    Analysis of Background Noise for Wireless Microwave LAN Channels

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    Perusal of the details within, should provide the reader with an insight into general wireless indoor communications within the microwave spectrum, with respect to the problems laced, specific to noise corruption of the transmitted signal. Indoor communication systems are difficult to model, due to the largely random nature of the relevant environment, and the compounding factors that degrade system performance. These factors are many and varied, in accordance with the operational topologies of possible application area. However, there exists a common and increasing need to effectively model the communication links in question. Part of this strategy involves having an understanding of what levels of background noise exist within the operational area involved, and to what degree it is variable in accordance with application and link topologies. It is this requirement that provided the catalyst for my investigations. This study investigates the various noise sources evident on the two frequency bands allocated for wireless LAN applications, and considers the relative importance of the findings. As further perusal will reveal, the major disturbance likely to affect such technologies, are microwave ovens, both on a domestic and commercial scale. A lull statistical analysis is presented for the spectrum distribution and corresponding power levels for microwave ovens, with the results being utilised to present an examination of the possible influence that they may have upon the system, and the significance of such claims

    Deep Space Network information system architecture study

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    The purpose of this article is to describe an architecture for the Deep Space Network (DSN) information system in the years 2000-2010 and to provide guidelines for its evolution during the 1990s. The study scope is defined to be from the front-end areas at the antennas to the end users (spacecraft teams, principal investigators, archival storage systems, and non-NASA partners). The architectural vision provides guidance for major DSN implementation efforts during the next decade. A strong motivation for the study is an expected dramatic improvement in information-systems technologies, such as the following: computer processing, automation technology (including knowledge-based systems), networking and data transport, software and hardware engineering, and human-interface technology. The proposed Ground Information System has the following major features: unified architecture from the front-end area to the end user; open-systems standards to achieve interoperability; DSN production of level 0 data; delivery of level 0 data from the Deep Space Communications Complex, if desired; dedicated telemetry processors for each receiver; security against unauthorized access and errors; and highly automated monitor and control

    NASA/ASEE Summer Faculty Fellowship Program

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    This document is a collection of technical reports on research conducted by the participants in the 1993 NASA/ASEE Summer Faculty Fellowship Program at KSC. The basic common objectives of the Program are: to further the professional knowledge of qualified engineering and science faculty members; to stimulate an exchange of ideas between participants and NASA; to enrich and refresh the research and teaching activities of participants' institutions; and to contribute to the research objectives of the NASA centers. 1993 topics include wide band fiber optic communications, a prototype expert/information system for examining environmental risks of KSC activities, alternatives to premise wiring using ATM and microcellular technologies, rack insertion end effector (RIEE) automation, FTIR quantification of industrial hydraulic fluids in perchloroethylene, switch configuration for migration to optical fiber network, and more

    The application of forward error correction techniques in wireless ATM

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    Bibliography: pages 116-121.The possibility of providing wireless access to an ATM network promises nomadic users a communication tool of unparalleled power and flexibility. Unfortunately, the physical realization of a wireless A TM system is fraught with technical difficulties, not the least of which is the problem of supporting a traditional ATM protocol over a non-benign wireless link. The objective of this thesis, titled "The Application of Forward Error Correction Techniques in Wireless ATM' is to examine the feasibility of using forward error correction techniques to improve the perceived channel characteristics to the extent that the channel becomes transparent to the higher layers and allows the use of an unmodified A TM protocol over the channel. In the course of the investigation that this dissertation describes, three possible error control strategies were suggested for implementation in a generic wireless channel. These schemes used a combination of forward error correction coding schemes, automatic repeat request schemes and interleavers to combat the impact of bit errors on the performance of the link. The following error control strategies were considered : 1. A stand alone fixed rate Reed-Solomon encoder/decoder with automatic repeat request. 2. A concatenated Reed-Solomon, convolution encoder/decoder with automatic request and convolution interleaving for the convolution codec. 3. A dynamic rate encoder/decoder using either a concatenated Reed-Solomon, convolution scheme or a Reed-Solomon only scheme with variable length Reed-Solomon words

    Dissertation submitted in partial fulfillment of the requirements for the Bachelor of Technology (Hons) (Information System)

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    Up until recently the whole area of video conferencing has proved to be an expensive and tricky technology to be working with. Most of the video conferencing technologies can be found in a large room video conferencing system with sophisticated and expensive conferencing equipments. And in other hand, teaching and learning process is still limited by physical boundaries. The main idea of this project is to improve communication and correlation among students, lecturers and tutors. The methodology chosen for the development of this project is Prototyping system development methodology. It consists of Requirement Analysis, Design Prototype, Evaluate Prototype and Project completion. In Requirement Analysis Phase, the requirements of the application and the functional specification are determined followed by Design Prototype Phase where all the critical part of this project is developed. These include the Graphical User Interface (GUI) development and the coding of this application. The third phase is Evaluate Prototype Phase where the testing phase took place. Each subcomponent is tested to make sure it met all requirements. Once all components of the application is tested and all requirements are satisfied, the last phase, that is Project Completion Phase are considered completed whereby final documentation are to be developed before the final presentation. As a conclusion, this project aims to improve current communication style. It consumes communication technology effectively whereby the processing power of desktop computers has almost reached a level to become comfortable with processing the multimedia data. In addition, advances in the bandwidth availability on the internet and on LAN's/ WAN's has given the networks the ability to handle the real time streaming media data

    An Assessment of Indoor Geolocation Systems

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    Currently there is a need to design, develop, and deploy autonomous and portable indoor geolocation systems to fulfil the needs of military, civilian, governmental and commercial customers where GPS and GLONASS signals are not available due to the limitations of both GPS and GLONASS signal structure designs. The goal of this dissertation is (1) to introduce geolocation systems; (2) to classify the state of the art geolocation systems; (3) to identify the issues with the state of the art indoor geolocation systems; and (4) to propose and assess four WPI indoor geolocation systems. It is assessed that the current GPS and GLONASS signal structures are inadequate to overcome two main design concerns; namely, (1) the near-far effect and (2) the multipath effect. We propose four WPI indoor geolocation systems as an alternative solution to near-far and multipath effects. The WPI indoor geolocation systems are (1) a DSSS/CDMA indoor geolocation system, (2) a DSSS/CDMA/FDMA indoor geolocation system, (3) a DSSS/OFDM/CDMA/FDMA indoor geolocation system, and (4) an OFDM/FDMA indoor geolocation system. Each system is researched, discussed, and analyzed based on its principle of operation, its transmitter, the indoor channel, and its receiver design and issues associated with obtaining an observable to achieve indoor navigation. Our assessment of these systems concludes the following. First, a DSSS/CDMA indoor geolocation system is inadequate to neither overcome the near-far effect not mitigate cross-channel interference due to the multipath. Second, a DSSS/CDMA/FDMA indoor geolocation system is a potential candidate for indoor positioning, with data rate up to 3.2 KBPS, pseudorange error, less than to 2 m and phase error less than 5 mm. Third, a DSSS/OFDM/CDMA/FDMA indoor geolocation system is a potential candidate to achieve similar or better navigation accuracy than a DSSS/CDMA indoor geolocation system and data rate up to 5 MBPS. Fourth, an OFDM/FDMA indoor geolocation system is another potential candidate with a totally different signal structure than the pervious three WPI indoor geolocation systems, but with similar pseudorange error performance

    Dissertation submitted in partial fulfillment of the requirements for the Bachelor of Technology (Hons) (Information System)

    Get PDF
    Up until recently the whole area of video conferencing has proved to be an expensive and tricky technology to be working with. Most of the video conferencing technologies can be found in a large room video conferencing system with sophisticated and expensive conferencing equipments. And in other hand, teaching and learning process is still limited by physical boundaries. The main idea of this project is to improve communication and correlation among students, lecturers and tutors. The methodology chosen for the development of this project is Prototyping system development methodology. It consists of Requirement Analysis, Design Prototype, Evaluate Prototype and Project completion. In Requirement Analysis Phase, the requirements of the application and the functional specification are determined followed by Design Prototype Phase where all the critical part of this project is developed. These include the Graphical User Interface (GUI) development and the coding of this application. The third phase is Evaluate Prototype Phase where the testing phase took place. Each subcomponent is tested to make sure it met all requirements. Once all components of the application is tested and all requirements are satisfied, the last phase, that is Project Completion Phase are considered completed whereby final documentation are to be developed before the final presentation. As a conclusion, this project aims to improve current communication style. It consumes communication technology effectively whereby the processing power of desktop computers has almost reached a level to become comfortable with processing the multimedia data. In addition, advances in the bandwidth availability on the internet and on LAN's/ WAN's has given the networks the ability to handle the real time streaming media data
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