Modeling the Effect of Optical Signal Multipath

Abstract

Here, we propose a model to determine the effect of multipath in indoor environments when the shape and characteristics of the environment are known. The main paper goal is to model the multipath signal formation to solve, as much as possible, the negative effects in light communications, as well as the indoor positioning errors due to this phenomenon when using optical signals. The methodology followed was: analyze the multipath phenomenon, establish a theoretical approach and propose different models to characterize the behavior of the channel, emitter and receiver. The channel impulse response and received signal strength are obtained from different proposed algorithms. We also propose steps for implementing a numerical procedure to calculate the effects of these multipaths using information that characterizes the environment, transmitter and receiver and their corresponding positions. In addition, the results of an empirical test in a controlled environment are compared with those obtained using the model, in order to validate the latter. The results may largely vary with respect to the cell size used to discretize the environment. We have concluded that a cell size whose side is 20-times smaller than the minimum distance between emitter and receiver (i.e., 10 cm × 10 cm for a 2-m distance) provides almost identical results between the empirical tests and the proposed model, with an affordable computational load.

Analysis of Multiple-Access Discrimination Techniques for the Development of a PSD-Based VLP System

“…The optical signal reflection model reported in [25] allows modeling how the multipath affects the measurement techniques based on AoA and PoA. In [26], a procedure was proposed to measure the signal value that impacts into the PSD (detector) surface as a result of MP. In [27], position errors due to MP were characterized by working with AoA and PoA techniques, to complement the previous works.…”

Indoor Positioning System Based on a PSD Detector, Precise Positioning of Agents in Motion Using AoA Techniques

“…An in-depth analysis is out of the scope of our paper (the MP effect will be studied in future works). However, in our related work [ 33 ], we have verified the effect of MP in our system and the result was that the fact of having obstacles that generate MP has a very little effect on the determination of the impact point with this technique. Note that the RSS received at each electrode of the PSD sensor is a subtractive composition of currents, which partially compensates the MP and their effect in the location determination.…”

Accuracy and Precision Assessment of AoA-Based Indoor Positioning Systems Using Infrastructure Lighting and a Position-Sensitive Detector

“…The latter, however, is a critical source of inaccuracy in optical IPSs. When the environment remains unchanged, partial compensation could be introduced by applying the model presented in [ 27 ] after characterization of the geometry and material composition of the environment. This, however, would require significant effort; multipath errors are therefore likely to remain the dominant source of error in most real applications.…”

“…A complete analysis and correction of these distortions was presented in [ 24 , 25 ]. A procedure to model and correct the errors due to multipath effects was proposed in [ 26 , 27 , 28 ]. From those previous works, it can be concluded that PSD-based IPSs using AoA observations provide better positioning performance than implementations using phase differences.…”