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.
Highlights
Wireless communications in indoor environments have witnessed substantial consolidation, especially those based on optical communications using infrared or visible signals (VLC)
30: end for 31: end if 32: end if 33: end function h is the impulse response; tx is the transmitter; rx is the receiver; s is the element that reflects the light from sant ; P is the signal strength; d is the distance; k is the number of rebounds from which to obtain the impulse response; and k i is a parameter that indicates the rebound for each iteration of the recursive algorithm
We calculated the signal strength that reached all of the cells into which the environment was divided within the FoV of the position-sensitive device (PSD)
Summary
Wireless communications in indoor environments have witnessed substantial consolidation, especially those based on optical communications using infrared or visible signals (VLC). Signals degrade, and intersymbol interference (ISI) increases, substantially reducing the bit rate; in ILPS, independently of the technology used, multipath may give rise to distance measurement errors of metric magnitudes, rendering it impossible to use an ILPS system without deploying multipath mitigation techniques Due to this drawback, it is of fundamental importance to develop a methodology and procedure with which to estimate the effect and error generated by multipath in a working environment with a given geometry. We present a proposal for a procedure and algorithms that make it possible to introduce the characteristics of the environment (e.g., models of the reflection from its different parts, geometric shape, size, conditions and constraints), the transmitter and the receiver and use this information to obtain the impulse response due to multipath generated by different reflections. The proposed composite signal (MP)model and procedure are based on the material reflection model given in [4], which was developed for this purpose
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