Combined Deterministic and Modified Monte Carlo Method for Calculating Impulse Responses of Indoor Optical Wireless Channels

Because of the importance of calculating an accurate impulse response of an indoor optical wireless room environment that includes sufficient orders of multipath reflections from reflecting surfaces of the room, several different algorithms exist to solve the problem of calculating impulse responses accurately and in a reasonable amount of computing time. Deterministic approaches that divide the reflecting surfaces into small elements give the best accuracy but they require high computing time. Modified Monte Carlo methods provide a very fast approach of calculating impulse responses but the calculated impulse responses contain variance or, in other words, they are not as temporally smooth when compared to deterministic approaches. In this paper, we have taken a combined approach where we calculate the contribution of first reflections to the total impulse response by a deterministic method, and then the contributions of second and rest of the reflections to the total impulse response are calculated by the Modified Monte Carlo method. This carries the advantage of both of these approaches. Moreover, the algorithm can be easily implemented for parallel computation similar to the Modified Monte Carlo method to utilize the full power of modern multicore computer processors.