Sökning: "spatial frequency"

Visar resultat 16 - 20 av 330 avhandlingar innehållade orden spatial frequency.

  1. 16. A Simulation Approach to High-Frequency Plasma Waves

    Författare :Etienne Koen; Tomas Karlsson; Orsolya Ferencz; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Electrostatic waves in the form of Broadband Electrostatic Noise (BEN) have been observed in the Earth's auroral region associated with high geomagnetic activity. This broad frequency spectrum consists of three electrostatic modes, namely electron plasma, electron acoustic and beam-driven modes. LÄS MER

  3. 17. Multiuser diversity orthogonal frequency division multiple access systems

    Författare :Patrick Svedman; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Signalbehandling; Signalbehandling; Signal processing; Signalbehandling;

    Sammanfattning : Multiuser diversity can be used to significantly increase system throughput in wireless communication systems. The idea is to schedule users when they experience good channel conditions and let them wait when the channels are weak. In this thesis, several aspects on multiuser diversity OFDMA systems are investigated. LÄS MER

  4. 18. Wideband Watt-Level Spatial Power-Combined Power Amplifier in SiGe BiCMOS Technology for Efficient mm-Wave Array Transmitters

    Författare :Artem Roev; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; integration; spatial power combining; substrate integrated waveguide; array amplifiers; RFIC;

    Sammanfattning : The continued demand for high-speed wireless communications is driving the development of integrated high-power transmitters at millimeter wave (mm-Wave) frequencies. Si-based technologies allow achieving a high level of integration but usually provide insufficient generated RF power to compensate for the increased propagation and material losses at mm-Wave bands due to the relatively low breakdown voltage of their devices. LÄS MER

  5. 19. Phase Transitions in Large Oscillator Lattices

    Författare :Per Östborn; Antikens kultur och samhällsliv; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Matematisk och allmän teoretisk fysik; thermodynamics; statistical physics; phase transition; limit cycle oscillator; frequency entrainment; synchronization; sinus node; classical mechanics; Mathematical and general theoretical physics; arrhythmia; gravitation; quantum mechanics; relativity; klassisk mekanik; kvantmekanik; relativitet; statistisk fysik; termodynamik; Fysicumarkivet A:2003:Östborn;

    Sammanfattning : This thesis deals with large networks of limit cycle oscillators. A limit cycle oscillator is a dynamical system that has a periodic attractor in phase space, and is defined in continuous time. To each such oscillator one can associate a natural frequency. LÄS MER

  7. 20. MIMO Channels - Measurements and Analysis

    Författare :Peter Almers; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Signalbehandling; Telecommunication engineering; Telekommunikationsteknik; Electrical engineering; Elektroteknik; Signal processing; Teknik; Capacity; Technological sciences; Spatial-multiplexing; Diversity; Measurements; MIMO; Wireless; Communications;

    Sammanfattning : Providing increased transmission speed, quality and an efficient spectrum utilization is crucial for high speed wireless services of today and the future. This thesis is a collection of papers that address an important step in that direction -- the utilization of the spatial domain of the wireless channel. LÄS MER