International Journal of Electrical and Computer Engineering (IJECE) Vol. 3, No. 3, June 2013, pp. 372~376 ISSN: 2088-8708  372 Journal homepage: http://iaesjournal.com/online/index.php/IJECE Radio Frequency Propagation Mechanisms and Empirical Models for Hilly Areas Famoriji John Oluwole*, Olasoji Yekeen Olajide** * Department of Electrical and Electronics Engineering ** Federal University of Technology, Akure Nigeria Article Info ABSTRACT Article history: Received Feb 22, 2013 Revised Apr 15, 2013 Accepted May 24, 2013 Achieving better network performance is a paramount concern in wireless networks. This paper provides a survey of the basic mechanisms which influence the propagation of electromagnetic waves in hilly areas. Three empirical models: COST231-Hata, Okumura-Hata and Egli which are suitable for path loss prediction for such area are presented. By using these propagation models the broadcast signal strength are predicted for this type of environment. Measurement results of signal strength in UHF band obtained in Idanre Town of Ondo State Nigeria are presented and compared with the results predicted by using the propagation models. A modified COST231-Hata radiowave propagation model was developed and implemented with Matlab GUI (Graphical User Interface) for simulation. The model developed has 93.8% accuracy. Keyword: Empirical models, Radiowave propagation Measurement Matlab GUI Copyright © 2013 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Famoriji John Oluwole, Department of Electrical and Electronics Engineering, Federal University of Technology, P. M. B. 704, Akure, Nigeria. E-mail: famorijijohn@yahoo.co.uk 1. INTRODUCTION Achieving optimal performance is a paramount concern in wireless networks. During radiowave propagation an interaction between waves and environment attenuates the signal level. It causes path loss and finally limits coverage area. Path loss prediction is a crucial element in the first step of network planning. The ability of determining optimum base-station locations, obtaining suitable data rates and estimating coverage without conducting a series of propagation measurements (which is very expensive and time consuming) can be achieved with empirical propagation models. Empirical propagation models are site specific; therefore selection of a suitable propagation model is the first step in the wireless network design. Okumura-Hata, COST231-Hata and Egli are widely used models for the path loss prediction in areas with high hill in frequency bands below 2 GHz. Another model for the band below 11 GHz has been developed by Stanford University, as an extension of the Hata model [1]-[3]. The COST-231 Hata wireless propagation model was devised as an extension to the Hata-Okumura model and the Hata model in [4]. The COST231-Hata model is designed to be used in the frequency band from 500 MHz to 2000 MHz. It also contains corrections for urban, suburban and rural (flat) environments. [4] reported :”although this models’ frequency range is outside that of the measurements, its simplicity and the availability of correction factors has seen it widely used for path loss prediction at this frequency band”. The basic equation for path loss in decibels (dB) is stated below as quoted from [4]:  ܮൌ Ͷ͸.͵ ൅ ͵͵.ͻ݋ ଵ଴ ሺሻ െ ͳ͵.ͺʹ݋ ଵ଴ ሺ ௕ ሻ െ  ௠ ൅ ൫ͶͶ.ͻ ൅ ͸.ͷͷ݋ ଵ଴ ሺ ௕ ሻ൯݋ ଵ଴ ൅ ௠ (1)  ௠ ൌ ͵.ʹͲ൫݋ ଵ଴ ሺͳͳ.͹ͷ ௥ ሻ൯ ଶ െ Ͷ.ͻ͹ (2)