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VLC system OOFDM modulation method based on hadamard matrix amplification

A modulation method and matrix technology, applied in the field of visible light communication, can solve the problems of noise sensitivity such as PSN, reduce the reliability of communication systems, etc., and achieve the effect of reducing PAPR and improving the ability to resist PSN.

Active Publication Date: 2018-05-15
SUN YAT SEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0018] The present invention provides a VLC system OOFDM modulation based on Hadamard matrix amplification in order to solve the technical defect that the ACO-OFDM communication system uses CI spreading codes for spreading to be more sensitive to PSN and other noises, which reduces the reliability of the communication system. method

Method used

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  • VLC system OOFDM modulation method based on hadamard matrix amplification
  • VLC system OOFDM modulation method based on hadamard matrix amplification
  • VLC system OOFDM modulation method based on hadamard matrix amplification

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Embodiment 1

[0043] The focus of the present invention is to use Hadamard matrix amplification to amplify the CI spreading code to form a HICI code that has both the ability to reduce the PAPR of the OOFDM communication system and the ability to resist PSN. Then, the present invention demonstrates the characteristic that Hadamard matrix amplification algorithm keeps matrix orthogonality, combines Hadamard matrix amplification algorithm and CI spreading code, based on image 3 The system in puts forward a specific modulation method and illustrates it with a specific example.

[0044] The earliest Hadamard matrix was first proposed by James Joseph Sylvester in 1867. Through the Hadamard matrix augmentation algorithm, the high-dimensional Hadamard matrix can be constructed by iterating the low-dimensional Hadamard matrix [4]. Assuming that the matrix H is a Hadamard matrix with dimension n, the Hadamard matrix iteration is defined as formula (6).

[0045]

[0046] Among them, H 2n is a ...

Embodiment 2

[0073] This embodiment analyzes the performance of the method in Embodiment 1, and analyzes the performance of the ACO-OFDM system signal to interference plus noise ratio (Signal to Interference plus Noise Ratio, SINR) through the PSN communication system model to verify the performance of the method proposed in the present invention. performance.

[0074] Since the photon emission of optical transmitters such as LEDs has certain random characteristics, the VLC system of high-power LEDs will generate PSN, which is related to the magnitude of the transmitted signal, and its distribution can be expressed as formula (12).

[0075]

[0076] where N represents a Gaussian distribution, σ 2 is the variance of the thermal noise, x is the transmitted signal, is the proportional relationship parameter between PSN and thermal noise, and its range can be determined according to literature [5].

[0077] The signal model in [6] is used for system SINR performance analysis. Such as ...

Embodiment 3

[0090] In order to verify the performance of the method in this embodiment, the image 3 The communication process of the ACO-OFDM system using the method described in the paper is simulated.

[0091] In the simulation, this paper adopts the typical VLC channel model in [7], and the specific simulation parameters are shown in Table 1. In the simulation, it is assumed that the thermal noise power is -60dBm, and the power of the LED is set according to a specific signal-to-noise ratio (Signal Noise Ratio, SNR).

[0092] Table 1: Simulation parameters

[0093]

[0094]

[0095] first to image 3 The PAPR performance of the ACO-OFDM system applying the method of the present invention is simulated and compared with the ACO-OFDM system that does not spread spectrum, Figure 4 is the PAPR complementary cumulative distribution function (Complementary Cumulative Distribution Function, CCDF) of the two systems. The CCDF function is defined as formula (18).

[0096] CCDF=P(PAP...

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Abstract

The invention provides a visible light communication (VLC) system optical orthogonal frequency division multiplexing (OOFDM) modulation method based on hadamard matrix amplification, which keeps the orthogonality characteristics of a matrix by utilizing hadamard matrix amplification, and forms an HICI code by performing the hadamard matrix amplification on a carrier interferometry (CI) spread code, so that code element interval of the HICI code and the CI spread code keeps consistent. Compared with the traditional CI spread code, the HICI code does not cause reduction of the code element interval along with the increasing of the number of subcarriers, and simultaneously has the capability of reducing OOFDM-based VLC system signal PAPR and the capability of withstanding PSN. Based on theoretical analysis and simulation results, the HICI code provided by the VLC system OOFDM modulation method based on hadamard matrix amplification, which is provided by the invention, improves the capability of the original CI spread code to withstand the PSN and simultaneously has the capability of reducing the OOFDM communication system PAPR.

Description

technical field [0001] The present invention relates to the technical field of visible light communication, and more specifically, relates to an OOFDM modulation method of a VLC system based on Hadamard matrix amplification. Background technique [0002] With the development of technology, lighting systems using light-emitting diodes (Light-emitting Diode, LED) have been widely used, and visible light communication (Visible Light Communication, VLC) technology based on LED lights has attracted the attention of researchers from various countries, and has gradually become a traditional technology. An important addition to wireless communication systems [1]. The VLC technology based on LED lights is mainly based on Intensity Modulation (IM) and Direct Detection (DD) technology, which uses the rapidly changing light intensity that can be ignored by human eyes to transmit information. Due to the random characteristics of the photon emission of LEDs, the high-power LED-based VLC ...

Claims

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Application Information

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IPC IPC(8): H04L27/26H04B10/548H04B1/707
CPCH04B1/707H04B10/548H04L27/2697
Inventor 卢怀因张琳
Owner SUN YAT SEN UNIV
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