Indoor visible light positioning method for inhibiting OCDMA (Optical Code Division Multiple Access) through NLOS

Abstract

The invention discloses an indoor visible light positioning method for inhibiting an OCDMA (Optical Code Division Multiple Access) by using an NLOS (Non-Local Of Sight), which is based on an OCDMA technology and effectively solves the problem that the positioning performance of the edge and the corner of a room is relatively poor due to the influence of a multipath effect in a traditional indoor visible light positioning system. According to the core idea of the method, an optical address code with good orthogonality is distributed to each LED, different LED signals are distinguished at a receiving end through inter-code orthogonality, correlation values are calculated, and the correlation values are combined with a corresponding positioning algorithm to complete positioning. Compared with a traditional positioning method, the design has the advantages that the traditional positioning method directly utilizes receiving power at a receiving end and combines a channel model for positioning, and the design realizes positioning by calculating a correlation value between a mixed signal and a local optical address code at the receiving end. Due to the low correlation between the NLOS (Non-Line-of-Sight) signal and the LOS (Line-of-Sight) signal, the influence of the NLOS signal on the result after the correlation calculation can be almost neglected, so that the positioning performance of the room edge, corner area and other areas which are greatly influenced by the NLOS signal can be improved, and the defects of the traditional positioning mode can be made up to a certain extent.

Description

technical field [0001] The invention belongs to the technical field of visible light communication, and is especially suitable for positioning in an indoor visible light model whose room positioning performance is greatly affected by multipath reflection. Background technique [0002] Different from the traditional indoor visible light positioning system, the traditional indoor visible light positioning system usually seldom considers the influence of multipath reflection in the room, but this technology fully considers the influence of multipath reflection on indoor positioning performance, especially the edge and corner of the room are affected. Reflection affects more serious areas; the reason for this method is first, in the actual scene, there will inevitably be multipath reflections in the room, and there will be more or less diffuse reflections on the four walls. This is based on the actual scene. of. The second reason is that OCDMA technology does not require strict...

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Problems solved by technology

[0004] So far, a large number of scholars have conducted in-depth research on indoor positioning technology based on frequency division multiplexing, and have achieved great results, but there are usually problems with filter design. Later, some scholars proposed to use DSP processing instead of filter design , but the problem is that a large amount of additional equipment is introduced, which greatly increases the cost of the system

In addition, in the positioning system of frequency division multiplexing, frequency adjustment is very inconvenient, especially when the number of LED lights in the LED network is large, it is impractical to adjust the frequency for each LED light

Therefore, some scholars have proposed an indoor positioning system based on time-division multiplexing technology. This system does not have these problems faced in the frequency-division multiplexing system, but it requires strict synchronization between the receiver and the transmitter, which is very difficult in practical applications. Difficult to achieve, especially in today's high-speed data transmission, it is very difficult to achieve strict synchronization of the system

The code division multiplexing uses the orthogonality between codes to distinguish different signals, and there is no problem of filter design, frequency adjustment, and synchronization. However, the address codes used in traditional code division multiplexing systems are mostly bipolar. suitable for optical systems

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