43 International Journal of Computing and ICT Research, Vol. 4, No. 1, June 2010 A Consideration of Propagation Loss Models for GSM during Harmattan in N’djamena (Chad) D.D. DAJAB AND NALDONGAR PARFAIT * Department of Electrical and Computer Engineering, AHMADU BELLO University, Zaria, Nigeria. Abstract The paper discusses the influence of propagation environment in a GSM mobile network. It considers the measurement and prediction results for a special case of propagation, that is, the harmattan, in a live network. The harmattan precipitation intensity may be so great that visibility at ground level is reduced to less than a hundred meters by dust clusters. In this paper, the path loss during harmattan in N’djamena (Chad) is computed from the received signal strength at various distances for three major roads. The Hata and Free-space models were applied, and compared with received signal measurement data. The results indicate that measurement data and the Hata prediction model agree closely while the free space model generally underestimates the path loss phenomena. The significance here is that various forms of precipitation such as rain, snow, cloud and fog absorb and scatter electromagnetic energy leading to attenuation in its signal strength. The study indicates that harmattan precipitates do inflict attenuation significantly. Categories and Subject Descriptors: C.4 [Performance of Systems]: Modeling Techniques; D4.8 [Performance]: Measurements; Modeling and Prediction; I6.4[Simulation and Modeling]:Model Validation and Analysis General Terms: Harmattan, Propagation, Signal Strength, Pathloss Additional Key Words: Global System for Mobile –Telephony (GSM), IJCIR Reference Format: D.D. Dajab and Naldongar Parfait. A Consideration of Propagation Loss Models for GSM during Harmattan in N’djamena (Chad). International Journal of Computing and ICT Research, Vol. 4, No. 1, pp. 43 - 48. http://www.ijcir.org/volume4-number1/article5.pdf. ______________________________________________________________________________________ 1. INTRODUCTION * Authors Address: D.D. Dajab and Naldongar Parfait, Department of Electrical and Computer Engineering, Ahmadu Bello University, Zaria, Nigeria.Email: dddajab@abu.edu.ng , pnaldongarmbete@yahoo.com "Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than IJCIR must be honored. Abstracting with credit is permitted. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee." © International Journal of Computing and ICT Research 2010. International Journal of Computing and ICT Research, ISSN 1818-1139 (Print), ISSN 1996-1065 (Online), Vol.4, No.1, pp. 43 – 48, June, 2010 ______________________________________________________________________________________