Wireless communication networks offer subscribers the possibilities of free mobility and access to information anywhere at any time. Therefore, electromagnetic coverage calculations are important for wireless mobile communication systems, especially in Wireless Local Area Networks (WLANs). Before any propagation computation is performed, modeling of indoor radio wave propagation needs accurate geographical information in order to avoid the interruption of data transmissions. Geographic Information Systems (GIS) and spatial interpolation techniques are very efficient for performing indoor radio wave propagation modeling. This paper describes the spatial interpolation of electromagnetic field measurements using a feed-forward back-propagation neural network programmed as a tool in GIS. The accuracy of Artificial Neural Networks (ANN) and geostatistical Kriging were compared by adjusting procedures. The feedforward back-propagation ANN provides adequate accuracy for spatial interpolation, but the predictions of Kriging interpolation are more accurate than the selected ANN. The proposed GIS ensures indoor radio wave propagation model and electromagnetic coverage, the number, position and transmitter power of access points and electromagnetic radiation level. Pollution analysis in a given propagation environment was done and it was demonstrated that WLAN (2.4 GHz) electromagnetic coverage does not lead to any electromagnetic pollution due to the low power levels used. Example interpolated electromagnetic field values for WLAN system in a building of Yildiz Technical University, Turkey, were generated using the selected network architectures to illustrate the results with an ANN.
A new delay-based long-term evolution scheduler is proposed in this paper. The scheduler allows sharing of radio and base station resources between different radio bearers. It provides a trade-off between user fairness and system performance. The proposed algorithm is based on the scheduler having knowledge of the age of real-time (RT) applications packets. By considering the age of the packet with the lean production concept, the scheduler can determine different types of RT application packets and must be scheduled within their packet delay budget. The proposed algorithm is called the delay-based lean scheduler (DBLS). Simulation results shows that the proposed DBLS algorithm provides superior throughput and delay performance to the modified largest weighted delay first (M-LWDF) algorithm irrespective of the number of users.
A coverage estimation based cellular system design in microcell structure under shadowing and multipath conditions is presented. The effect of the signal weakening conditions is examined by log -normal shadowing/Rayleigh fading distribution. By taking the ap plication values of GSM operating systems and cellular phones, area reliability and cell radius are calculated and reliable RF coverage is investigated.
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