Visar resultat 1 - 5 av 1668 avhandlingar innehållade ordet spectrum.
1. On Finding Spectrum Opportunities in Cognitive Radios : Spectrum Sensing and Geo-locations Database
Sammanfattning : The spectacular growth in wireless services imposes scarcity in term of the available radio spectrum. A solution to overcome this scarcity is to adopt what so called cognitive radio based on dynamic spectrum access. LÄS MER
Sammanfattning : Spectrum is a natural and limited resource that needs to be managed both internationally and nationally because of the unique propagation characteristics of radio waves. Once transmitted, a radio signal propagates until its power is depleted. Furthermore, electromagnetic energy does not recognize borders between countries. LÄS MER
Sammanfattning : There is consensus among economists, engineers, and lawyers that a traditional command-and-control approach to spectrum assignment is inefficient and that a market-based or commons approach can be more efficient. The purpose of this thesis is to find the benefits of using spectrum commons for frequency assignment in Thailand. LÄS MER
4. Topics in Dynamic Spectrum Access : Market Based Spectrum Sharing and Secondary User Access in Radar Bands
Sammanfattning : The steady growth in demand for spectrum has increased research interest in dynamic spectrum access schemes. This thesis studies some challenges in dynamic spectrum access based on two strategies: open sharing and hierarchical access. LÄS MER
Sammanfattning : Relations to the effective diffusion constant and the relaxation rate of the time-dependent diffusion coefficient for porous systems are derived from the Laplace operator spectrum. The Padé approximation is then explained in terms of the Laplace operator spectrum. LÄS MER