Computational Problems of Electrical Engineering

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    Technical сonfiguration of TV white space devices: a conceptual view
    (Publishing House of Lviv Polytechnic National University, 2013) Gepko, Igor
    As it is known, to eliminate interference, the frequency reuse approach is followed in digital TV (DTV) planning similar to cellular networks, avoiding the use of the same channel in two neighboring allotments. There are large areas where certain groups of TV channels are not deliberately used. They are called white spaces in TV spectrum (TVWS). Considering the great economical value of TV spectrum, it was proposed to use TVWSs for low-power wireless networking on non-interfering (secondary) basis with the licensed (primary) DTV service. At the same time, restrictions imposed on white space devices (WSDs) to protect primary users should not devaluate spectrum for secondary use. The lack of knowledge about the locations of primary receivers, as well as the unreliable estimation of the aggregate interference impact caused by the large number of secondary devices accessing the spectrum are reported to be among the key challenges for the use of TVWSs. In our view, parameters for the protection of primary system should be based on the determination of minimum separation distance, which by all means should be observed at a certain area. A required shadow margin, as well as a multi-user margin should be calculated for such a minimum safety range. To reuse spectrum efficiently, mobile/portable WSDs should support dynamic power control ability which has to play a key role in sensing and operate with the lower power??? when a TV signal is weak. Except for providing WSDs with a list of available channels, the geolocation database should contain recommended parameters for path loss calculations, as well as minimum distances which could be ensured for a certain inhabited locality. У цій статті запропоновано метод кодування для зниження рівня позасмутових випромінювань у комунікаційних системах із сигналами з багатьма носіями.