Clutter Height Variation Effects on Frequency Dependen Path Loss Models at UHF Bands in Build-Up Areas
In this work, the performance of eight prominent empirical path loss models and a localized model, in predicting path losses in build up areas is investigated. Multi-transmitter electromagnetic field strength measurements were conducted, using a dedicated Agilent spectrum analyzer, along five predefined routes in Osun State, Nigeria. The measured data were compared with the model predictions. Path profile and terrain undulations effects have been observed on the received signal. For all the routes and transmitters, Okumura, SUI models over predicted the path losses, while Ericsson model under predicted the losses. However, Hata, Davidson, Cost 231 and ILORIN models generally show promising results with varying performance. The average mean error values of 55.11 dB, -8.53 dB, 46.72 dB, -9.81 dB, -28.16 dB, -8.93 dB, -30.59 dB, -22.95 dB and -12.57 dB are respectively obtained for NTAOSOGBO transmitter for Okumra, Hata, SUI, Cost 231, CCIR, Davidson, Ericsson, EEC-33 and ILORIN models. In terms of RMSE, the average RMSE values of 9.24 dB, 9.08 dB and 9.18 dB were obtained for ILORIN, Hata and Davidson models respectively. This trend was found to be similar for other transmitters i.e. OSBC, NDTV and NTA Ile Ife with varying performances among the four contending models. We, further, examined the route performance for the two main contending models i.e. ILORIN and Hata models. Inconsistency in terms of the performance for each model were observed, however the localized model i.e. ILORIN was found to provide optimum path loss prediction with considerable accuracy, over the other models. With the aforementioned, we believe the results and observations presented would provide guide to radio system engineers in making informed choices on the applicability and predictability of such models in the terrain of Osun State and other similar build-up areas in Nigeria.
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