Abstract
In this paper, the performance of the optimal beam radius indoor positioning (OBRIP) and two-receiver indoor positioning (TRIP) algorithms are analysed by varying system parameters in the presence of an indoor optical wireless channel modelled in line of sight configuration. From all the conducted simulations, the minimum average error value obtained for TRIP is 0.61 m against 0.81 m obtained for OBRIP for room dimensions of 10 m × 10 m × 3 m. In addition, for each simulated condition, TRIP, which uses two receivers, outperforms OBRIP and reduces position estimation error up to 30%. To get a better understanding of error in position estimation for different combinations of beam radius and separation between light emitting diodes, the 90th percentile error is determined using a cumulative distribution frequency (CDF) plot, which gives an error value of 0.94 m for TRIP as compared to 1.20 m obtained for OBRIP. Both algorithms also prove to be robust towards change in receiver tilting angle, thus providing flexibility in the selection of the parameters to adapt to any indoor environment. In addition, in this paper, a mathematical model based on the concept of raw moments is used to confirm the findings of the simulation results for the proposed algorithms. Using this mathematical model, closed-form expressions are derived for standard deviation of uniformly distributed points in an optical wireless communication based indoor positioning system with circular and rectangular beam shapes.
Highlights
Global positioning system (GPS) has revolutionised the realm of outdoor environment positioning and tracking systems [1,2,3,4], but its usability in the indoor environment is questionable [5,6]owing to attenuation effects and multipath interference [3,7,8]
With the help of exhaustive parameter analysis in terms of 90th percentile value found from the cumulative distribution frequency (CDF) and average error for the proposed algorithms, this paper provides a large set of values for system parameters like beam radius, light emitting diodes (LEDs) separation distance and receiver separation distance for which the error in position estimation is within sub-metre accuracy
The two-receiver indoor positioning (TRIP) algorithm further reduces the error obtained from the optimal beam radius indoor positioning (OBRIP) algorithm by up to 30%
Summary
Global positioning system (GPS) has revolutionised the realm of outdoor environment positioning and tracking systems [1,2,3,4], but its usability in the indoor environment is questionable [5,6]. Owing to recently proposed techniques aiding signal separation at the receiver, discussed, a new positioning algorithm called the optimal beam radius indoor positioning (OBRIP) algorithm is proposed in [26] This algorithm takes the advantage of the overlapping LED light beam regions to further improve position estimation accuracy of proximity based IPS by generating more reference points for position assignment. It is designed for an indoor environment with an array of LEDs pre-installed at fixed positions continuously transmitting their location coordinates as modulated optical signals.
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