The Influence of Terrain Scattering on Radio Links in Hilly/Mountainous Regions

Current rural propagation models only consider paths (direct, ground reflected, terrain diffracted, troposphere scattered) that lie in the vertical plane containing the transmitter and receiver. This paper shows that nonspecular scattering from terrain can give significant additional contributions to the received signal in hilly/mountainous environments. To show this, we have carried out Monte Carlo simulations of scattering in many different types of rural regions. These simulations model scattering using the bi-static radar equation with a Lambert's law coefficient. In order to permit simulations for many radio links and many terrain databases, we have developed a novel algorithm to rapidly search for terrain scattering elements that are visible to both the transmit and receive antennas. Results show that in sufficiently rugged terrain, the scattered paths can give a greater contribution to received power than vertical plane paths in more than 80% of links. Conclusions are drawn for radio channel characteristics, such as angle spread and short-term spatial fading. Statistical models dependent on terrain variation for path loss, and temporal response are also developed.

[1]  J. Epstein,et al.  An Experimental Study of Wave Propagation at 850 MC , 1953, Proceedings of the IRE.

[2]  C. M. Chang,et al.  A comparison of point-to-point computer aided radio propagation models with field test data , 1988, 38th IEEE Vehicular Technology Conference.

[3]  W. Randolph Franklin.  Higher isn ’ t Necessarily Better : Visibility Algorithms and Experiments , 1994 .

[4]  A. G. Longley,et al.  PREDICTION OF TROPOSPHERIC RADIO TRANSMISSION LOSS OVER IRREGULAR TERRAIN. A COMPUTER METHOD-1968 , 1968 .

[5]  Jeffrey Boksiner,et al.  Dependence of radio channel characteristics on terrain variability in hilly/mountainous regions , 2011, 2011 - MILCOM 2011 Military Communications Conference.

[6]  P. Kuhlmann,et al.  A three-dimensional wave propagation model for macrocellular mobile communication networks in comparison with measurements , 1996, Proceedings of Vehicular Technology Conference - VTC.

[7]  Marc J. van Kreveld,et al.  Region Intervisibility in Terrains , 2007, Int. J. Comput. Geom. Appl..

[8]  Kamal Sarabandi,et al.  Measurement and modeling of the millimeter-wave backscatter response of soil surfaces , 1996, IEEE Trans. Geosci. Remote. Sens..

[9]  Antti Toskala,et al.  LTE for UMTS - OFDMA and SC-FDMA Based Radio Access , 2009 .

[10]  Borut Zalik,et al.  Comparison of viewshed algorithms on regular spaced points , 2002, SCCG '02.

[11]  Lance Williams,et al.  Casting curved shadows on curved surfaces , 1978, SIGGRAPH.

[12]  Adib Y. Nashashibi,et al.  MMW Polarimetric Radar Bistatic Scattering From a Random Surface , 2007, IEEE Transactions on Geoscience and Remote Sensing.

[13]  Laura Toma,et al.  Computing visibility on terrains in external memory , 2007, JEAL.

[14]  J. D. Parsons,et al.  Characterisation of mobile radio signals in rural areas , 1991 .

[15]  F. Ulaby,et al.  Handbook of radar scattering statistics for terrain , 1989 .

[16]  Ali Abdi,et al.  Comparison of the level crossing rate and average fade duration of Rayleigh, Rice and Nakagami fading models with mobile channel data , 2000, Vehicular Technology Conference Fall 2000. IEEE VTS Fall VTC2000. 52nd Vehicular Technology Conference (Cat. No.00CH37152).

[17]  Anja Klein,et al.  Direction-of-arrival of partial waves in wideband mobile radio channels for intelligent antenna concepts , 1996, Proceedings of Vehicular Technology Conference - VTC.

[18]  Peter E. Driessen.  Prediction of multipath delay profiles in mountainous terrain , 2000, IEEE Journal on Selected Areas in Communications.

[19]  Chris W. Johnson.  Radio Access Networks for UMTS , 2008 .

[20]  B. Allen,et al.  Spatial channel characterization for smart antenna solutions in FDD wireless networks , 2004, IEEE Transactions on Antennas and Propagation.