Simulation of multipath impulse response for indoor wireless optical channels

Abstract

Abstract-We present a recursive method for evaluating the impulse response of an indoor free-space optical channel with Lambertian reflectors. The method, which accounts for multiple reflections of any order, enables accurate analysis of the effects of multipath dispersion on high-speed indoor optical communication systems. We present a simple algorithm for computer implementation of the technique. We present computer simulation results for both line-of-sight and diffuse transmitter configurations. In both cases, we flnd that reflections of multiple order are a significant murce of intersymbol interference. We also report experimental measurements of optical multipath, which help verify the accuracy of our simulations.

Receiver alignment dependence of a GA controlled optical wireless transmitter

“…The computational time required for calculation of the impulse response using this iterative method is proportional to k 2 [23], and we will firstly limit ourselves to the a third order impulse response (k = 3), and secondly change the segmentation resolution of the environment for each reflection, setting ∆A 1 = 20, ∆A 2 = 6 and ∆A 3 = 2. It should also be noted that the resultant impulse response in (2) will result in the finite sum of scaled delta functions which need to undergo temporal smoothing by subdividing time into bins of width ∆t, and summing the total power in each bin [21]. For this work, we assume a single time bin width of ∆t = 0.1ns.…”

“…It is also known [21,15] that, for an intensity modulation, direct detection (IM/DD) channel, where the movement of transmitters, receivers or objects in the room is slow compared to the bit rate of the system, no multipath fading occurs, and, as such, can be deemed an LTI channel. The impulse response h(t; S i , R j ) is given by [21,22] …”

“…Under the assumption that all surfaces exhibit Lambertian reflection characteristics, we follow the technique described in [21], and partition all surfaces into L elements E l with position r E l , orientationn E l , and size A E l = 1/∆A 2 (m 2 ), where ∆A is the desired number of elements per meter. A given element will sequentially behave, firstly as a receiver E R l with a hemispherical FOV, for which we can determine the received power P E l , and secondly as a source E S l , with a radiation intensity profile R(φ) as given by (1) setting n = 1 and P S i = ρ E l P E l , where ρ E l is the reflectivity of the element.…”

A Photon Modeling Method for the Characterization of Indoor Optical Wireless Communication

“…A wireless communication system that uses visible light has many advantages with which it is possible to use very simple transmitter/receiver structures and easy to install; thus it receives much interest [1][2][3][4]. However, optical waves have very high frequency and their properties differ from conventional radio waves.…”

“…The conventional approaches are based on the ray tracing techniques [3][4][5], which take the properties of optical waves into consideration. The method launches a bundle of rays in every direction in the space and tracks the ray paths.…”