Abstract-Demand for wireless communication technologies and systems keep increasing and has reached the peak where the capacity can only be achieved by improving spectrum utilization. The spectrum allocated to TV broadcast systems can be shared by wireless data services through exploiting spatial reuse opportunities (Spatial TV white space).Path loss models are used extensively in signal prediction, coverage optimization and interference analysis. Recently it is being used in estimating distances for safe operation of secondary users in TV white space. Peculiarities of these models give rise to high prediction errors when deployed in a different environment other than the one initially built for. It is however not very clear which model gives the best fit and what the penalties are for using the models outside the intended coverage area. In this paper, we assess the fitness of nine empirical widely used path loss models using five novel metrics to gauge their performance. In order to achieve this, field strength measurements were conducted in the VHF and UHF regions along six different routes that spanned through the urban, suburban and rural areas of Kwara State, Nigeria. A program was developed in VB 6.0 language to compute the path losses for the empirical models. The measurement results were converted to path losses and are compared with the model's prediction. The results show that no single model provides a good fit consistently. However, Hata and Davidson models provide good fitness along some selected routes with measured RMSE values of less than 10 dB. ITU-R P.1546-4, Walfisch Ikegami (WI), Egli, CCIR and FSPL perform woefully, with higher RMSE and SC-RMSE (Spread Corrected RMSE) values. Further analysis on the error spread as a function of distance along 60 km route revealed that Hata and Davidson models show symmetry up to about 30 km with slight divergence between 24 km and 30 km after which Davidson model gives lower prediction error along the route. The prediction errors for Davidson model distributes nearly symmetrically around the mean error of 2.15 dB. It is noteworthy that the Gaussian error distribution within the window of ±5 dB dominates the frequency counts. However, the error counts for CCIR model closely follow normal distribution with a mean error of −6.37 dB but Hata, FSPL, Walfisch Ikegami and ITU-R P. 529-3 models do not follow normal distribution curve.

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In this work, signal path loss prediction from nine different empirical path loss models were statistically compared with those measured from four television transmitters along five routes that span through urban and rural environments of Osun State, Nigeria. In this respect, results obtained show that both Hata and Davidson prediction models provide best fit prediction consistently along the five measurement routes with 90% to 98% prediction accuracy, Ilorin, CCIR, Cost 231, Ericsson 9999 and ECC-33 show prediction accuracy within the range of 65% to 80% while SUI and Okumura models offer prediction accuracy within the range of 15% to 21%. Generally the results show that Davidson and Hata models have better results in all the five routes examined. SUI and Okumura models show the least performance results.

Abstract-Continuing proliferation of wireless devices exposes humanity to the reality of the twin challenge posed by finite frequency spectrum and almost infinite demand for the same frequency spectrum, necessitating the need for more ingenious spectrum management techniques. The band 2.4-2.7 GHz was originally created and classified for ISM, 3G, UMTS and WiMAX systems. It has become a frequency band which is generally used by end users due to the fact that it's inexpensive, easy to deploy and enhances frequency re-use. Quite a few measurements have been carried out in countries like France, Germany, India, Romania, UK and USA. This paper presents a study of an outdoor measurement on spectrum occupancy in both rural and urban areas in Kwara State, Nigeria, spanning across the frequency range of 2.4 GHz -2.7 GHz. The results show that the band being investigated is immensely underutilized with upper and lower occupancy values of 22.56% and 0% in urban and rural environments. These results were compared to other measurements conducted globally in this band or closely aligned bands.Index Terms-ISM band, spectrum occupancy, spectrum utilization, UMTS network.

Path-loss model is essential for proper planning of emerging technologies in the broadcast frequency band. Characterisation of the radio channel is paramount for accurate prediction of TV coverage, and achievement of peaceful coexistence between the TV (primary users) and other new infrastructures (secondary users). In this paper, field strength measurements are conducted along six routes that spanned through urban, suburban and rural areas of Kwara State, Nigeria. The measurement results are compared with path-loss prediction of eight widely used empirical models. Least squares and linear iterative methods are employed to optimise Hata-Davidson's model, as it showed best fit compared with other models. The predictions of the tuned model are compared with other models in terms of relative error, mean error, skewness, root mean square errors and normalised error probability density function. Results of the simulations indicate that the optimised model gives better values for the metrics considered.

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