Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 31 for “"SATELLITE LINKS"”.
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Rain scatter interference in satellite links
… to inducing attenuation and depolarization in satellite links can create intersystem interference. This type of interference was investigated extensively in the 1970's for terrestrial links, but little has been done to study its effects on modern and future satellite links. This thesis reports …
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Enhancing the performance of TCP over satellite links
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.
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Adaptive power control as a fade countermeasure on satellite links
Satellite systems in the 20/30 GHz band are very susceptible to outages due to rain-induced fades. In order to reduce the impact of these fades, it has been proposed that the power of the uplink station transmitter be adjusted during the fade to compensate. This dissertation will explore some of …
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Sensor Package Analysis and Simulation for Direct Sensor-to-Satellite Links
… microsensors that communicate directly to a satellite or a constellation of satellites. Information is spread using pseudo noise (PN) or Barker codes. The sensors use a single circular microstrip patch element with a wide beamwidth or a miniature phased array antenna that continuously scans …
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Interactions between TCP and link layer protocols on mobile satellite links
High speed satellite-based data networks are highly desirable for a variety of mobile applications. In order to inter-operate with existing networks, satellite-based systems must support TCP/IP traffic. However, TCP performs poorly on land-mobile satellite channels because of large propagation …
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Parameterized analysis of optical inter-satellite links for high resolution satellite communication
… Antenna arrays have been deployed in single satellite applications but arrays have not been exploited in multi-satellite constellations where increased array size enables high spatial selectivity between ground transmitters. One requirement for these array systems is sufficient fidelity in …
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100 Gbps ptical coherent modem for low earth orbit optical inter-satellite links
… a viable and cost-effective solution for future satellite systems with advantages in bandwidth, unregulated frequencies, and reduced system mass, volume, and power consumption in comparison with radio frequency systems. Several FSOC systems successfully demonstrated links between spacecraft and …
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An Analytical Tool for Calculating Co-Channel Interference in Satellite Links That Utilize Frequency Reuse
… in the downlink and in the uplink of a single satellite/space-based mobile communications system, due to the reuse of frequencies in spot beams or coverage cells. The analysis and computer code can be applied to any type of satellite or platform elevated at any height above earth. The cells or …
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Frequency scaling of rain attenuation on satellite links in the Ku/Ka-bands using OLYMPUS satellite data
… need to exploit higher frequency bands. Most satellite communications traffic now use C-band (4-8 GHz) and Ku-band (12-18 GHz). The next approved, yet largely unused, frequency allocation for domestic use is in the K-band (18-27 GHz) to Ka-band (27-40 GHz). At these higher frequencies, …
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A simple model for the depolarizing effects of rain and ice on earth satellite links in the 10 to 30 GHz frequency range
This thesis reports the results of a thorough study into the effects of rain and ice on the polarization reuse technique for earth-space communications. Precipitation in the form of rain and ice leads to significant depolarization and attenuation of dual polarized signals above about 10 GHz. The …
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Efficient spectrum-handoff schemes for cognitive radio networks
… risks to mobile ground stations; while inter-satellite links can interfere with terrestrial radio astronomy observations. Terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations also require mechanisms that will enhance the performance of their …
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Dynamics and Control of Satellite Relative Motion: Designs and Applications
… an exact and efficient analytic solution of satellite relative motion using a direct geometrical approach in spherical coordinates. The resulting solution is then transformed into general parametric equations of cycloids and trochoids. With this transformation, the dissertation presents new …
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Performance analysis of HDLC protocol operating in asynchronous balanced mode
… full-duplex transmission on error prone links. This thesis extends work done by Bux et al. [8] by considering errors on both the links. Satellite links have long propogation delays compared to terrestrial links, and hence, have longer error recovery times. For such links, errors in …
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Reliable broadband satellite-integrated network design through propagation and networking solutions
Satellites will play an indispensable role in the deployment of commercial networks to meet an increasing demand for supporting multimedia services at high data rates. Next generation satellite systems, operating at high frequency bands offer large bandwidth and are able to provide broadband …
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Trellis-based iterative decoding of block codes for satellite ATM
In power-limited channels such as satellite links, error control codes are needed to provide high performance at very low Signal-to-Noise Ratios (SNRs). Turbo Codes or concatenated codes with iterative decoding, can achieve a performance very close to the Shannon limit. They are the most powerful …
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ΜΕΛΕΤΗ ΚΑΙ ΥΠΟΛΟΓΙΣΜΟΣ ΤΗΣ ΕΠΙΘΥΜΗΤΗΣ ΠΡΟΠΑΡΑΜΟΡΦΩΣΗΣ ΓΙΑ ΤΗΝ ΔΙΟΡΘΩΣΗ ΤΗΣ ΕΙΣΑΓΟΜΕΝΗΣ ΠΑΡΑΜΟΡΦΩΣΗΣ ΣΕ ΜΗ ΓΡΑΜΜΙΚΟΥΣ ΠΟΛΥΕΠΙΠΕΔΟΥΣ ΨΗΦΙ...
… AND MORE INFORMATION VIA DIGITAL TERRESTRIAL AND SATELLITE LINKS HAS BECOME AN URGENT DEMAND. BECAUSE OF THE LIMITED BANDWIDTH AVAILABILITY, THE CURRENT TREND IS TO IMPROVE THE SPECTRUM EFFICIENCY OF THE MICROWAVE SYSTEMS, USING M-ARY DIGITAL SCHEMES SUCH AS M-ARY QAM [1.4]. IN FACT M- ARYQAM …
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Medium Access Control Protocol for Satellite Constellations
Satellite internet constellations have emerged as a promising solution for providing global internet connectivity, especially in regions underserved by terrestrial infrastructure. However, as user demand increases, especially in densely populated urban areas, existing Medium Access Control (MAC) …
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Minimum-delay HF communications
… over fiber-optics and are more economical than satellite links in long-distance communication applications. As a result, there is renewed interest in the field of HF from the high-frequency trading industry, as a means of transmitting financial data. Ideally, decisions should be made on received …
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Statistical modeling for land mobile satellite communications
The Land Mobile Satellite System (LMSS) to be available in the 1990 time frame will provide connection between mobile vehicles and the conventional terrestrial communication network. The design is dependent on the propagation characteristics of the land mobile satellite signal. Unlike fixed …
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