volume | PIER Journals

Abstract

In this paper, measurement, modeling and validation of existing models on the effect of nonhomogeneous vegetation on UHF radio-wave propagation through a long forested channel at frequency of 1835 MHz are reported. The paper focuses on vegetation attenuation measurement through a long forested channel of about 8 km long with mixed vegetation of different density. The measured data were fitted using exponential decay function, and a new model was proposed from the fitted curve. The new proposed model will take care of the limitation in vegetation depth posted by some existing models. Generic models, mainly modified exponential decay and analytical models were also fitted to the data and validated, while RMSE was used to determine the best model that describes the data. The evaluated data results show that all the models tested give significant errors which show that they are not suitable for long forested channel scenario. Though COST 235 has the least error (17.05 dB), the error is still significant because COST 235 could only account for vegetation attenuation of short distance scenario. Attenuation shows corresponding increase with increase in leaves thickness in the forested channel considered, which was due to complex permittivity of the leaves moisture content and the dielectric properties of the leaves saline water. The developed model and other results obtained in this study will help to improve prediction accuracy of the effects of vegetation attenuation in nonhomogeneous vegetation along forested channels and also help in establishing efficient UHF radio link budget for long forested channel scenario.

1. Savage, N., D. L. Ndzi, A. Seville, E. Vilar, and J. Austin, "Radio wave propagation through vegetation: Factors influencing signal attenuation," Radio Science, Vol. 38, No. 5, 1088, 2003.
doi:10.1029/2002RS002758 Google Scholar

2. Ndzi, D. L., L. M. Kamarudin, A. A. Mohammad Ezanuddin, A. Zakaria, R. B. Ahmad, M. F. B. A. Malek, A. Y. M. Shakaff, and M. N., "Vegetation attenuation measurements and modeling in plantations for wireless sensor network planning," Progress In Electromagnetic Research B, Vol. 36, 283-301, 2012.
doi:10.2528/PIERB11091908 Google Scholar

3. Meng, Y. S., Y. H. Lee, and B. C. Ng, "Study of propagation loss prediction in forest environment," Progress In Electromagnetic Research B, Vol. 17, 117-133, 2009.
doi:10.2528/PIERB09071901 Google Scholar

4. De Jong, Y. L. C. and M. H. A. J. Herben, "A tree scattering model for improved propagation prediction in urban microcells," IEEE Transactions on Vechular Technology, Vol. 53, No. 2, 503, 2004.
doi:10.1109/TVT.2004.823493 Google Scholar

5. Saxton, J. A. and J. A. Lane, "VHF and UHF reception," Wireless World, Vol. 61, No. 5, 229-232, 1995. Google Scholar

6. Al-Nuaimi, M. O. and A. Hammoudeh, "Measurement and prediction of attenuation and scatter of microwave signals by trees," IEEE Proceedings — Microwaves Antennas and Propagation, Vol. 141, No. 2, 70-76, 1994.
doi:10.1049/ip-map:19949840 Google Scholar

7. Weissberger, M. A., An initial critical summary of models for predicting the attenuation of radio waves by foliage, Electromagnetic Compatibility Analysis Center, Annapolis, MD, ECAC-TR-81- 101, 1981.

8. Ishimaru, A., Wave Propagation and Scattering in Random Media, Academic Press, 1978.

9. CCIR, , Influences of terrain irregularities and vegetation on troposphere propagation, 235-236 CCIR Report, Geneva, 1986.

10. COST235, , Radio propagation effects on next-generation fixed-service terrestrial telecommunication systems, Final Report, Luxembourg, 1996.

11. Al-Nuaimi, M. O. and R. B. L. Stephens, "Measurements and prediction model optimization for signal attenuation in vegetation media at centimetre wave frequencies," IEE Proc. Microw. Antennas Propagation, Vol. 145, No. 3, 201-206, 1998.
doi:10.1049/ip-map:19981883 Google Scholar

12. Seville, A. and K. H. Craig, "Semi-empirical model for millimetre-wave vegetation attenuation rates," Electron. Lett., Vol. 31, No. 17, 1507-1508, 1995.
doi:10.1049/el:19951000 Google Scholar

13. Seville, A., "Vegetation attenuation: Modeling and measurements at millimetric frequencies," Proc. 10th IEE Int. Conf. Antennas Propagation, 2.5-2.8, Edinburgh, Scotland, Apr. 1997.

14. Schwering, F. K., E. J. Violette, and R. H. Espeland, "Milliameter-wave propagation in vegetation, experiments and theory," IEEE Trans. Geosci. Remote Sensing, Vol. 26, No. 3, 355-367, 1988.
doi:10.1109/36.3037 Google Scholar

15. Wang, F. and K. Sarabandi, "An enhanced millimeter-wave foliage propagation model," IEEE Trans. Antennas Propagation, Vol. 53, No. 7, 2138-2145, 2005.
doi:10.1109/TAP.2005.850704 Google Scholar

16. Lin, Y. C. and K. Sarabandi, "A Monte Carlo coherent scattering model for forest canopies using fractal-generated trees," IEEE Trans. Geosci. Remote Sensing, Vol. 37, No. 1, 440-451, 1999.
doi:10.1109/36.739083 Google Scholar

17. Koh, I. S. and K. Sarabandi, "Polarimetric channel characterization of foliage for performance assessment of GPS receivers under tree canopies," IEEE Trans. Antennas Propagation, Vol. 50, No. 5, 713-726, 2002.
doi:10.1109/TAP.2002.1011239 Google Scholar

18. Adewumi, A. S., M. O. Alade, and H. K. Adewumi, "Development of an inbuilt UHF signal and weather parameters measuring system," International Journal for Research in Applied Science & Engineering Technology (IJRASET), Vol. 3, No. 8, 280-288, 2015. Google Scholar

19. McDonald, K. C., M. C. Dobson, and F. T. Ulaby, "Using MIMICS to model L-band multi angle andmulti temporal backscatter from a walnutorchard," IEEE Trans. Geosci. Remote Sensing, Vol. 28, 477-491, 1990.
doi:10.1109/TGRS.1990.572925 Google Scholar

20. Karam, M. A., A. K. Fung, R. H. Lang, and N. S. Chauhan, "A microwave scattering model for layered vegetation," IEEE Trans. Geosci. Remote Sensing, Vol. 30, 767-784, 1992.
doi:10.1109/36.158872 Google Scholar

Dr. Adebayo Segun Adewumi

Dr. Olusegun Olabisi