High frequency methods resort to numerical ray tracing for application to complex environments. A new method based on the geometrical projection performed by a ray-congruence has been developed as a preconditioning of the ray tracing procedure. It builds a visibility tree, i.e., a database, storing information on all possible ray paths inside a scenario. The method gives a solution to a class of open problems of ray tracing techniques: ray missing, double (multiple) counting, termination criterion, calculation upgrade. Other features of the method are the multipath map and the multipath classification that allow the user to know the relevance of multipath at any point of the scenario in advance, before ray-tracing calculation. The method can be systematically applied to scenarios pertaining to different applications provided that the objects belong to the class of polyhedrons. Reflected and diffracted contributions in a scene are modelled as secondary sources which are handled with an off-line electromagnetic field calculation. Numerical analysis is provided showing the efficiency of the method.
2. Hussar, P., V. Oliker, H. L. Riggins, E. M. Smith-Rowland, W. M. Klocko, and L. Prussner, "AAPG2000: An implementation of the UTD on facetized CAD platform models," Ant. Prop. Mag., Vol. 42, No. 2, 100-106, 2000.
3. Wang, N., Y. Zhang, and C. H. Liang, "Creeping ray-tracing algorithm of UTD method based on NURBS models with the source on surface," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 14, 1981-1990, 2006.
4. Jin, K. S., T. I. Suh, S. H. Suk, B. C. Kim, and H. T. Kim, "Fast ray tracing using a space-division algorithm for RCS prediction," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 1, 119-126, 2006.
5. Bang, J. K., B. C. Kim, S. H. Suk, K. S. Jin, and H. T. Kim, "Time consumption reduction of ray tracing for RCS prediction using efficient grid division and space division algorithms," Journal of Electromagnetic Waves and Applications, Vol. 21, No. 6, 829-840, 2007.
6. Iskander, M. F and Z. Yun, "Propagation prediction models for wireless communications systems," IEEE Trans. Microwave Theory and Technique, Vol. 50, 662-673, March 2002.
7. Yun, Z., Z. Zhang, and M. F. Iskander, "A ray-tracing method based on the triangular grid approach and application to propagation prediction in urban environments," IEEE Trans. Antennas Propag., Vol. 50, 750-758, May 2002.
8. Rizk, K., J. F. Wagen, and F. Gardiol., "Two-dimensional ray-tracing modeling for propagation prediction in microcellular environments," IEEE Trans. Veh. Technol., Vol. 46, 508-517, May 1997.
9. Liang, G. and H. L. Bertoni, "A new approach to 3-D ray-tracing for propagation prediction in cities," IEEE Trans. Antennas Propag., Vol. 46, 853-863, June 1998.
10. Catedra, M. F., J. Perez, F. Saez de Adana, and O. Gutierrez, "Efficient raytracing technique for three-dimensional analyses of propagation in mobile communications: Application to picocell and microcell scenarios," IEEE Antennas Propag. Mag., Vol. 40, 15-27, April 1998.
11. Torres, R. P., L. Valle, M. Domingo, and S. Loredo, "An efficient ray tracing method for radiopropagation based on the modified BSP algorithm," IEEE Veh. Technol. Conference, Vol. 4, 1967-1971, September 1999.
12. Ng, K. H., E. K. Tameh, A. Doufexi, M. Hunukumbure, and A. R. Nix, "Efficient multielement ray tracing with sitespecific comparisons using measured MIMO channel data," IEEE Trans. Veh. Technol., Vol. 56, 1019-1032, May 2007.
13. Fugen, T., J. Maurer, T. Kayser, and W. Wiesbeck, "Capability of 3-D ray tracing for defining parameter sets for the specification of future mobile communications systems," IEEE Trans. Antennas Propag., Vol. 54, 3125-3137, November 2006.
14. Chiu, C. C and T. C. Tu, "Path loss reduction in an urban area by genetic algorithms," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 3, 319-330, 2006.
15. Liang, C. H., Z. L. Liu, and H. Di, "Study on the blockage of electromagnetic rays analytically," Progress In Electromagnetics Research B, Vol. 1, 253-268, 2008.
16. Kara, A. and E. Yazgan, "Modelling of shadowing loss due to huge non-polygonal structures in urban radio propagation," Progress In Electromagnetics Research B, Vol. 6, 123-134, 2008.
17. Yang, C. F., B. C. Wu, and C. J. Ko, "A ray tracing method for modeling indoor wave propagation and penetration," IEEE Trans. Antennas Propag., Vol. 46, 907-919, June 1998.
18. Suzuki, H. and A. S. Mohan, "Measurement and prediction of high spatial resolution indoor radio channel characteristic map," IEEE Trans. Veh. Technol., Vol. 49, 1321-1333, July 2000.
19. Teh, C. H. and H. T. Chuah, "A path-corrected wall model for ray-tracing propagation modeling," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 2, 207-214, 2006.
20. Chen, C. H., C. L. Liu, C. C. Chiu, and T. M. Hu, "Ultra-wide band channel calculation by SBR/IMAGE techniques for indoor communication," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 1, 41-51, 2006.
21. Liu, Y. J., Y. R. Zhang, and W. Cao, "A novel approach to the refraction propagation characteristics of UWB signal waveforms," Journal of Electromagnetic Waves and Applications, Vol. 21, No. 14, 1939-1950, 2007.
22. Degli-Esposti, V., F. Fuschini, E. M. Vitucci, and G. Falciasecca, "Measurement and modelling of scattering from buildings," IEEE Trans. Antennas Propag., Vol. 55, 143-153, January 2007.
23. Kloch, C., G. Liang, J. B. Andersen, G. F. Pedersen, and H. L. Bertoni, "Comparison of measured and predicted time dispersion and direction of arrival for multipath in a small cell environment," IEEE Trans. Antennas Propag., Vol. 49, 1254-1263, September 2001.
24. Chen, Z., H. L. Bertoni, and A. Delis, "Progressive and approximated techniques in ray-tracing-based radio wave propagation prediction models," IEEE Trans. Antennas Propag., Vol. 52, 240-251, January 2004.
25. Son, H. W. and N. H. Myung, "A deterministic ray tube method for microcellular wave propagation prediction model," IEEE Trans. Antennas Propag., Vol. 47, 1344-1350, August 1999.
26. Rajkumar, A., B. F. Naylor, F. Feisullin, and L. Rogers, "Predicting RF coverage in large environments using ray-beam tracing and partitioning tree represented geometry," Wireless Networks, Vol. 2, 143-154, 1996.
27. Teh, C. H. and H. T. Chuah, "An improved image-based propagation model for indoor and outdoor communication channels," Journal of Electromagnetic Waves and Applications, Vol. 17, 31-50, January 2003.
28. Sabbadini, M., F. Bardati, and E. Di Giampaolo, "A recursive beam-splitting algorithm for forward ray tracing," Proc. USNC/URSI National Radio Science Meeting, 203, July 1999.
29. Di Giampaolo, E., M. Sabbadini, and F. Bardati., "Astigmatic beam tracing for GTD/UTD methods in 3-D complex environments," Journal of Electromagnetic Waves and Applications, Vol. 15, 439-460, April 2001.
30. Di Giampaolo, E., F. Bardati, and M. Sabbadini, "Preconditioned astigmatic beam tracing for urban propagation," IEEE Microwave and Wireless Components Letters, Vol. 13, 296-298, August 2003.
31. Di Giampaolo, E., Electromagnetic characterization of inter-vehicle communications, IEEE Communications Society, Wireless Rural and Emergency Communications Conference (WRECOM), Rome, Italy, October 1-2, 2007.
32. Foley, J. D., A. Van Dam, S. K. Feiner, and J. F. Hughes, Computer Graphics: Principles and Practice, Addison-Wesley, Reading, MA, 1990.
33. Di Giampaolo, E. and F. Bardati, "GTD ray tracing by topological mapping," Proc. IEEE Antennas and Propag. Society Int. Symp., Vol. 1B, 673-676, July 2005.
34. O'Rourke, J. E., "Visibility," Handbook of Discrete and Computational Geometry, J. E. Goodman and J. O'Rourke (eds.), 467-479, CRC Press, 1997.
35. Di Giampaolo, E. and F. Bardati, "Analytical model of multiple wedge-diffracted ray congruence," Electromagnetics, Vol. 23, 509-524, August 2003.
36. Thibault, W. C. and B. F. Naylor, "Set of operations on polyhedra using BSP trees," Proc. 14th Annu. Conf. Computer Graphics and Interactive Techniques, SIGGRAPH'87, Vol. 21, 153-162, August 1987.
37. Di Giampaolo, E. and F. Bardati, "A deterministic tool for multipath propagation modelling," Proc. IEEE Antennas and Propag. Society Int. Symp., Vol. 3, 2231-2234, June 2004.
38. Di Giampaolo, E., "Astigmatic beam tracing for multipath prediction in urban environment," Proc. URSI EMTS, 606-608, May 2004.
39. Galati, G., M. Leonardi, E. Di Giampaolo, and S. Barbera, "Multipath evaluation for multilateration systems in complex airport scenario," Proceedings of International Radar Symposium (IRS), September 2007.
40. Erricolo, D., G. D'Elia, and P. L. E. Uslenghi, "Measurements on scaled models of urban environments and comparison with ray-tracing propagation simulation," IEEE Trans. Antennas Propag., Vol. 50, 727-735, May 2002.
41. Xu, Y., Q. Tan, D. Erricolo, and P. L. E. Uslenghi, "Fresnel-Kirchhoff integral for 2-D and 3-D path loss in outdoor urban environments," IEEE Trans. Antennas Propag., Vol. 53, 3757-3766, November 2005.
42. Whitteker, J. H., "Measurements of path loss at 910MHz for proposed microcell urban mobile systems," IEEE Trans. Veh. Technol., Vol. 37, 125-129, August 1988.