Sökning: "multi-beam"

Visar resultat 6 - 8 av 8 avhandlingar innehållade ordet multi-beam.

  1. 6. Sparse Array Synthesis of Complex Antenna Elements

    Författare :Carlo Bencivenni; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; mutual coupling; array signal processing; maximally sparse array; aperiodic array; symmetric layout.; phase scanning; compressive sensing;

    Sammanfattning : Arrays of antennas can significantly improve the performances and extend the capabilities of single-element antennas. However, antenna arrays are expensive solutions and therefore it is critical to keep the costs to a minimum. LÄS MER

  3. 7. Cross-layer Aspects in OFMDA Systems : Feedback, Scheduling and Beamforming

    Författare :Patrick Svedman; Björn Ottersten; Ana I. Pérez-Neira; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Telecommunication; Telekommunikation;

    Sammanfattning : This thesis mainly studies the downlink of a wireless multiuser system, where the transmitter has limited knowledge about the communication channels of the users. Key techniques to improve the performance of such systems are, for instance, multiple antennas, multiuser diversity and orthogonal frequency-division multiple access (OFDMA). LÄS MER

  4. 8. Diffuse Optical Spectroscopy and Imaging of Turbid Media

    Författare :Can Xu; Atomfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; upconverting nanoparticles; luminescence; fluorescence; inverse problem; diffuse reflection spectroscopy; biomedical optics; photon migration; biomedical imaging; gas spectroscopy; medical diagnostics; tomography; Fysicumarkivet A:2013:Xu;

    Sammanfattning : This thesis deals with optical spectroscopy and imaging of complex and strongly scattering turbid media. Focus is mainly placed on three topics, being i) diffuse optical spectroscopy of choroidal tumors, ii) gas spectroscopy in scattering materials using the GASMAS (gas in scattering media absorption spectroscopy) technique, and iii) luminescence diffuse optical imaging and tomography of tissues. LÄS MER