Coverage Determination of Incumbent System and Available TV White Space Channels for Secondary Use in Ethiopia

Different path loss modelsare used to analyze the behavior of terrestrial television signals. The path loss calculated by one model differs from the other depending on different factors they consider. Frequency is one of the main factors included in each model. The frequency variation in the electromagnetic spectrum causes different response for each model. In terrestrial TV signal representation, since it is operating under VHF and UHF spectrum range, the propagation model used to model the signal must be less invariant when the transmitter is operating in VHF and UHF. If the pathloss model used is very variant it is difficult to define the coverage of the transmitters. This causes interference among transmitters and between the digital terrestrial TV transmitters and TV white space devices. Different propagation models are analyzed by their sensitivity to frequency variation from very-high and ultra-high frequency spectrums. After the best model is selected, we have used this model to find the coverage of the incumbent transmitter, which then is used to analyze free channels for secondary use. First the pathloss at VHF and then for UHF is calculated. This difference is then compared and the result indicates that ITU-R P.1546–5, which incorporate terrain data is best of others. Using this model and further analyze the coverage and free channels, we have found a minimum of 408 MHz free contiguous bandwidth, by considering a worst-case scenario, which is placing a WSD at the incumbent transmitter.

Design and Analysis of a Microstrip Patch Antenna for TV White Space Data Applications

In the present study, an algorithm for big data encryption has been designed which is concerned with encrypting data in a short time and in a safe manner and difficult to be penetrated by attackers and hackers according to the mechanism used for encryption in this study.The proposed algorithm is a development of an earlier NSCT algorithm. This development is based on adding a key expansion mechanism to generate keys by F-function, and also the number of cycles have been reduced to get less time. The proposed algorithm has been implemented in three stages; the first stage is implemented by FELICS simulation to find out the efficiency of the algorithm. In thesecond stage the proposed algorithm is implemented on the Java language to encrypt the text and to find out the execution time for the encryption. In the last step, the proposed algorithm is implemented on the MATLAB language to encrypt images and to knowthe performance of the algorithm in terms of countering attacks by hackers.After performing these steps and obtaining the results presented in this study, we can say that the proposed algorithm is capable of dealing with big data and that it can be considered safe and free from risks

Design and Analysis of a Microstrip Patch Antenna for TV White Space Data Applications

The increasing number of smart and wireless devices demandsfor a more flexible allocation in the higher frequency spectrum. Dynamic spectrum access isone of the major candidates tosolve the problem of spectrum scarcity. TV white spaces(TVWS)provide a means to opportunistically use the underutilized TVfrequency bandsin consideration with the gradual switching of the traditional TV broadcast to digital broadcasting.With smart devices in mini, micro, or nano circuit packaging, one of themajor challenges is in thedesign of compact transceiver antennassuitable for mobiledevices that operates in the Ultra High Frequency (UHF)band.This paper provides a brief overview of TVWS and aproposedmicrostrip patch antenna design.Thegeometric measurements and the antenna parameters were designedand simulated in MATLAB. Results show a resonant performance at the 638 MHz operating frequency and a high front-to-back power ratio in the radiation pattern. The radiation characteristics are almost omni-directional in the azimuth while directional in the elevation plane. There is a minimal radiation at the back hence, for thin and slim devices, this will suit the desired application