204 research outputs found

    Applications of satellite technology to broadband ISDN networks

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    Two satellite architectures for delivering broadband integrated services digital network (B-ISDN) service are evaluated. The first is assumed integral to an existing terrestrial network, and provides complementary services such as interconnects to remote nodes as well as high-rate multicast and broadcast service. The interconnects are at a 155 Mbs rate and are shown as being met with a nonregenerative multibeam satellite having 10-1.5 degree spots. The second satellite architecture focuses on providing private B-ISDN networks as well as acting as a gateway to the public network. This is conceived as being provided by a regenerative multibeam satellite with on-board ATM (asynchronous transfer mode) processing payload. With up to 800 Mbs offered, higher satellite EIRP is required. This is accomplished with 12-0.4 degree hopping beams, covering a total of 110 dwell positions. It is estimated the space segment capital cost for architecture one would be about 190Mwhereasthesecondarchitecturewouldbeabout190M whereas the second architecture would be about 250M. The net user cost is given for a variety of scenarios, but the cost for 155 Mbs services is shown to be about $15-22/minute for 25 percent system utilization

    Spectrally efficient and low cost time and wavelength division multiplexed passive optical network systems

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    The next-generation passive optical network stage 2 (NG-PON2) intends to support stacking 10 Gb/s wavelengths and maintaining the compatibility with the deployed legacy passive optical network (PON) systems. Essentially, Time and Wavelength Division Multiplexed-PON (TWDM-PON) is the best solution for NGPON2 that aims to support a symmetric 40 Gb/s data rate transmission, a split ratio of 1:64 and a distance up to 60 km. Unfortunately, most of the existing low cost and practical TWDM-PON solutions are still incapable to support remote users and inefficient for spectral bandwidth in higher services. Typically, low cost transceivers are avoided as they suffer from significant frequency chirp that seriously impact its transmission performance at the bit rate above 10 Gb/s. Therefore, the objectives of this thesis are to improve the current TWDM-PON power budget in supporting more access services reaching the remote customers to enhance the bandwidth capacity at lower cost and to reduce the complexity implementation problem. This is achieved by overcoming the significant frequency chirp of the low cost transceivers used such as reflective semiconductor optical amplifier (RSOA) and directly modulated lasers (DMLs), which are suitable for high data rate transmission. The RSOA chirp is mitigated using a single bi-pass delay interferometer (DI) at the optical line terminal (OLT) while the DML chirp is managed by ensuring its resulting current is in phase with the bandwidth enhancement factor, , at both optical network unit (ONU) and OLT. Apart from that, DML equipped with dispersion compensation fiber (DCF) technique for power budget improvement is also proposed. Furthermore, low cost schemes for even higher data rate TWDM-PON up to 56 Gb/s is proposed utilizing highly spectral efficient 16-quadrature amplitude modulation (16-QAM). The results are obtained from physical layer simulation, OptisystemTrademark and MatlabTrademark, where relevant significant parts are verified through theoretical analysis. The simulation results demonstrate a sufficient dispersion compensation with a record of 56.6 dB power bughet for DML-based TWDM-PON transmission system. While results are not absolute due to variations that can occur in practical implementation, analysis demonstrates the feasibility of the proposed methods

    Data distribution satellite

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    A description is given of a data distribution satellite (DDS) system. The DDS would operate in conjunction with the tracking and data relay satellite system to give ground-based users real time, two-way access to instruments in space and space-gathered data. The scope of work includes the following: (1) user requirements are derived; (2) communication scenarios are synthesized; (3) system design constraints and projected technology availability are identified; (4) DDS communications payload configuration is derived, and the satellite is designed; (5) requirements for earth terminals and network control are given; (6) system costs are estimated, both life cycle costs and user fees; and (7) technology developments are recommended, and a technology development plan is given. The most important results obtained are as follows: (1) a satellite designed for launch in 2007 is feasible and has 10 Gb/s capacity, 5.5 kW power, and 2000 kg mass; (2) DDS features include on-board baseband switching, use of Ku- and Ka-bands, multiple optical intersatellite links; and (3) system user costs are competitive with projected terrestrial communication costs

    Optical fibre distributed access transmission systems (OFDATS)

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    On-board B-ISDN fast packet switching architectures. Phase 1: Study

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    The broadband integrate services digital network (B-ISDN) is an emerging telecommunications technology that will meet most of the telecommunications networking needs in the mid-1990's to early next century. The satellite-based system is well positioned for providing B-ISDN service with its inherent capabilities of point-to-multipoint and broadcast transmission, virtually unlimited connectivity between any two points within a beam coverage, short deployment time of communications facility, flexible and dynamic reallocation of space segment capacity, and distance insensitive cost. On-board processing satellites, particularly in a multiple spot beam environment, will provide enhanced connectivity, better performance, optimized access and transmission link design, and lower user service cost. The following are described: the user and network aspects of broadband services; the current development status in broadband services; various satellite network architectures including system design issues; and various fast packet switch architectures and their detail designs

    Small business innovation research. Abstracts of 1988 phase 1 awards

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    Non-proprietary proposal abstracts of Phase 1 Small Business Innovation Research (SBIR) projects supported by NASA are presented. Projects in the fields of aeronautical propulsion, aerodynamics, acoustics, aircraft systems, materials and structures, teleoperators and robots, computer sciences, information systems, data processing, spacecraft propulsion, bioastronautics, satellite communication, and space processing are covered

    Satellite fixed communications service: A forecast of potential domestic demand through the year 2000. Volume 3: Appendices

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    Voice applications, data applications, video applications, impacted baseline forecasts, market distribution model, net long haul forecasts, trunking earth station definition and costs, trunking space segment cost, trunking entrance/exit links, trunking network costs and crossover distances with terrestrial tariffs, net addressable forecasts, capacity requirements, improving spectrum utilization, satellite system market development, and the 30/20 net accessible market are considered

    Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

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    Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression

    High-speed Modelocked Semiconductor Lasers And Applications In Coherent Photonic Systems

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    1.55-µm high-speed modelocked semiconductor lasers are theoretically and experimentally studied for various coherent photonic system applications. The modelocked semiconductor lasers (MSLs) are designed with high-speed (\u3e5 GHz) external cavity configurations utilizing monolithic two-section curved semiconductor optical amplifiers. By exploiting the saturable absorber section of the monolithic device, passive or hybrid mode-locking techniques are used to generate short optical pulses with broadband optical frequency combs. Laser frequency stability is improved by applying the Pound-Drever-Hall (PDH) frequency stabilization technique to the MSLs. The improved laser performance after the frequency stabilization (a frequency drifting of less than 350 MHz), is extensively studied with respect to the laser linewidth (~ 3 MHz), the relative intensity noise (RIN) (\u3c -150 dB/Hz), as well as the modal RIN (~ 3 dB reduction). MSL to MSL, and tunable laser to MSL synchronization is demonstrated by using a dual-mode injection technique and a modulation sideband injection technique, respectively. Dynamic locking behavior and locking bandwidth are experimentally and theoretically studied. Stable laser synchronization between two MSLs is demonstrated with an injection seed power on the order of a few microwatt. Several coherent heterodyne detections based on the synchronized MSL systems are demonstrated for applications in microwave photonic links and ultra-dense wavelength division multiplexing (UD-WDM) system. In addition, efficient coherent homodyne balanced receivers based on synchronized MSLs are developed and demonstrated for a spectrally phase-encoded optical CDMA (SPE-OCDMA) system

    Space station data system analysis/architecture study. Task 4: System definition report

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    Functional/performance requirements for the Space Station Data System (SSDS) are analyzed and architectural design concepts are derived and evaluated in terms of their performance and growth potential, technical feasibility and risk, and cost effectiveness. The design concepts discussed are grouped under five major areas: SSDS top-level architecture overview, end-to-end SSDS design and operations perspective, communications assumptions and traffic analysis, onboard SSDS definition, and ground SSDS definition
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