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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

New sharing method between the Fixed Satellite Service and the Aeronautical Mobile Satellite Service in the 14.0-14.5 GHz band

Smith, Justin L. 10 February 2003 (has links)
In the US, the 14.0-14.5 GHz band is allocated on a primary basis to the Radio-Navigation and the FSS with a secondary allocation to the LMSS. The Radio-Navigation service is the use of RADAR for navigation. An example of Radio-Navigation is the ground proximity radar used for airplane collision avoidance. FSS stands for the Fixed Satellite Service. In general, an FSS is a satellite network consisting of a geo-stationary satellite and non-movable earth stations on the ground. An example of an FSS is the earth terminals used at gas stations to verify credit cards and centrally track inventory. The 14.0-14.5 GHz band is also allocated on a secondary basis to the LMSS or Land Mobile Satellite Service. This is a satellite network with a satellite and a movable terrestrial non-aeronautical earth station. An example of an LMSS is a system called Omnitracs, which provides a satellite-based data connection for the trucking industry. AMSS stands for the Aeronautical Mobile Satellite Service. An AMSS is an LMSS dedicated only to airplanes. The CPM or Conference Preparatory Meeting after WRC or World Radio Conference-2000 decided there was an urgent need for technical and regulatory studies covering sharing between the FSS and the AMSS. The requirement for a report on the studies was added to the WRC-2003 agenda. The WRC also stipulated that the studies must demonstrate that sharing between the FSS and the AMSS is feasible enough to allocate AMSS a secondary status in the band. The studies need to be completed before WRC-2003. AMSS contends that sharing is feasible if their service can meet the same PFD limits of the LMSS. Presently, the FCC has licensed the AMSS on an experimental non-interference basis. The FSS contends that characteristics are needed of the AMSS system and a detailed sharing study be completed to verify sharing is feasible. The FSS believes that sharing may not be feasible if the same transponder is used for AMSS and FSS. The FSS perceives that the AMSS is asking for a super secondary status. Super secondary status implies that the AMSS would only be required to adhere to PFD limits on individual aircraft and not for multiple aircraft in view of a victim FSS receiver. Future studies will clarify this issue. The issues associated with the sharing analysis are; the modeling of the orbital separation of the satellites, the atmospheric interference into the communication link and the availability of the communication link between the FSS and the AMSS. The issues associated with modeling of the simulation are the static, verses dynamic modeling environments and developing a dynamic software tool to track airplane movement. This thesis plans to propose a new sharing methodology between the FSS and the AMSS that could be contributed to the WRC-2003 agenda. Three systems examples were provided at ITU meetings inresponse to the WRC-2003 agenda item. The three systems will abide by the ITU-R S.728 EIRP limits. The three systems indicate that static analysis shows that sharing is feasible involving only one aircraft as the interfere. This is not a reasonable solution for a real time environment because there is only one aircraft used. It is necessary for the link to support multiple aircraft. The factors that indicate sharing is feasible are: non-harmful interference to the victim and reasonable enough link margin in the interfere system to make it viable. A viable system in the case of aircraft would include high-speed internet and video. The AMSS interfere system cannot propose a power limit that will not allow it to close it's own link. In order to mitigate the interference, systems can agree to certain interference mitigation techniques. The different techniques are: transmitting power control, geostationary arc avoidance angle and orbital arc separation. Power control as described above is the centralized control of the interfering antenna into the victim. This is done by simulating the interference environment and pre-scheduling the decreases of the transmitting power. This is a feasible solution except that it decreases the availability and thru-put of the interfere system. This approach can make the system have unrealistic link margins and spotty availability due to the pre-scheduled power control. Another technique is the geostationary arc avoidance angle. This technique is not applicable since both the AMSS and FSS use geostationary orbits. The third technique is geostationary separation. This technique requires co-channel systems to maintain a certain orbital spacing between them. FSS systems in certain bands have a minimum of 3 degrees of orbital spacing between co-channel systems. Since the AMSS has 01/25/03 a mobile terrestrial system (aircraft) as part of the link, it requires a higher orbital separation between it and the FSS system. The results of dynamic analysis indicate that this technique is feasible at 10 degree orbital spacing. The Monte Carlo analysis completed for this thesis simulated the results of four scenarios: co-located, 3 degree, and 5 and 10-degree orbital separation. It can be determined from the results that the interference decreases as the orbital separation increases. These simulations were done based on a 10 aircraft interfere scenario. / Master of Science
2

Modeling and analysis of wireless cognitive radio networks: a geometrical probability approach

Ahmadi, Maryam 04 February 2016 (has links)
Wireless devices and applications have been an unavoidable part of human lives in the past decade. In the past few years, the global mobile data traffic has grown considerably and is expected to grow even faster in future. Given the fact that the number of wireless nodes has significantly increased, the contention and interference on the license-free industrial, scientific, and medical band has become severer than ever. Cognitive radio nodes were introduced in the past decade to mitigate the issues related to spectrum scarcity. In this dissertation, we focus on the interference and performance analysis of networks coexisting with cognitive radio networks and address the design and analysis of spectrum allocation and routing for cognitive radio networks. Spectrum allocation enables nodes to construct a link on a common channel at the same time so they can start communicating with each other. We introduce a new approach for the modeling and analysis of interference and spectrum allocation schemes for cognitive radio networks with arbitrarily-shaped network regions. First, for the first time in the literature, we propose a simple and efficient approach that can derive the distribution of the distance between an arbitrary interior/exterior reference point and a random point within an arbitrary convex/concave irregular polygon. This tool is essential in analyzing important distance-related performance metrics in wireless communication networks. Second, considering the importance of interference analysis in cognitive radio networks and its important role in designing spectrum allocation schemes, we model and analyze a heterogeneous cellular network consisting of several cognitive femto cells and a coexisting multi-cell network. Besides the cumulative interference, important distance-related performance metrics have been investigated, such as the signal-to-interference ratio and outage probability. Finally, the spectrum allocation and routing problems in cognitive radio networks have been discussed. Considering a wireless cognitive radio network coexisting with a cellular network with irregular polygon-shaped cells, we have used the tools developed in this dissertation and proposed a joint spectrum allocation and routing scheme. / Graduate
3

Výuka gramatiky ruského jazyka v českých učebních souborech pro úroveň B1 v porovnání s požadavky Standardu pro výuku ruštiny jako cizího jazyka / Teaching grammar of Russian language in Czech learning resources for level B1 compared to the requirements of the Standard for teaching Russian as a foreign language

Mrázková, Andrea January 2021 (has links)
This diploma thesis deals with the grammar curriculum of Russian language in the Czech teaching resources for B1 level and compares it with the requirements of the Standard for teaching Russian as a foreign language. The theoretical part of the thesis defines terms related to grammar; it describes and compares Czech and Russian curriculum documents and concerns with the Russian grammar teaching in the communicative approach. The last chapter of this part discusses the role of a teaching resource in the teaching process, the selection of such a resource and the description of individual resources for B1 level. The practical part presents the results of the content analysis of the teaching resources with respect to their minimum required grammar, which is first described individually for each resource and then compared with the requirements of the Standard for teaching Russian as a foreign language. Afterwards, the results are clearly summarized. KEY WORDS: minimum required grammar, morphology, syntax, teaching grammar, positive transfer, negative transfer, analysis

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