Accuracy and computational efficiency improvement of ray tracing using line search theory

This study presents a new ray tracing acceleration technique for site-specific propagation modelling in indoor environments. It overcomes one of the major problems regarding the computational efficiency of shooting-and-bouncing-ray (SBR) method, that is most of the rays emitted from the source do not reach the receiver whereas all of them must be traced. Our proposed method solves this problem in a two-step procedure based on the idea of line search theory. In the first step, called the bracketing phase, the solid angles around the transmitter that transport electromagnetic power to the receiver are determined. In the second step, called the sectioning or zoom phase, the accuracy is improved by iteratively increasing the tessellation frequency of the source in the power-transporting solid angles. No ray will be sent through non-power-transporting solid angles in the sectioning phase. Applying the method to a typical indoor problem is presented and the results are compared with fully 3-D SBR simulation. It is observed that power-transporting solid angles constitute only a small fraction of the total space around the source through which the rays are launched. Therefore a high gain in terms of computational efficiency (about 550-800- saving in the simulation time) is achieved.