Ray-tracing algorithms for fast calculation of the channel impulse response on diffuse IR wireless indoor channels

A modified Monte Carlo algorithm for the calculation of the impulse respons e on infrared wireless indoor channels is presented. As is well known, the characteristics of the room where the IR diffuse channel is implemented can lead to problems in communication, such as a multipath penalty on the maxi mum baud rate or hidden-station situations. Classical algorithms require la rge computational effort to calculate the impulse response in an ordinary-s ize room. Monte Carlo offers the possibility of validating the assumptions made for these classic algorithms (basically, the Lambertian nature of all reflections) with a computational complexity that is determined by the accu racy desired by the user. We have developed a mixed ray-tracing-determinist ic algorithm that assures that each ray contributes to the final channel re sponse function as many times as it rebounds with an obstacle. It increases dramatically the number of contributions and reduces, to the same extent, the time required for an accurate simulation. Extensive simulation results are presented and are compared with those of other simulation methods. We d emonstrate that the method presented here is much faster than Monte Carlo c lassical simulation schemes. It can be used as a method of simulation in it self or as a validation algorithm for other comparative studies of pulse br oadening. (C) 2000 Society of Photo-Optical Instrumentation Engineers. [S00 91-3286(00)00909-0].