Mobility visible light communication channel equalization method

A technology for visible light communication and channel equalization, applied in the field of visible light communication, can solve the problems of long OFDM signal symbol length, reducing the effect of channel equalization, and inability to reflect, and achieve the effect of simplifying the estimation process, accurate estimation effect and equalization effect.

Active Publication Date: 2019-01-25
NANJING UNIV OF POSTS & TELECOMM
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Problems solved by technology

Therefore, for a time-varying visible light channel, only relying on the training sequence of the starting position cannot reflect the real channel condition of the receiver's current location, which will greatly reduce the effect of channel equalization and affect the transmission quality of the system. Moreover, the OFDM signal The length of the code element is long, and the channel is easy to change, so it is more necessary to track the channel in real time than the single-carrier system

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  • Mobility visible light communication channel equalization method
  • Mobility visible light communication channel equalization method
  • Mobility visible light communication channel equalization method

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Embodiment Construction

[0032] The present invention will be further explained below in conjunction with the accompanying drawings.

[0033] Such as figure 1 As shown, the OFDM multipath signal caused by multiple light sources and reflections is received by the mobile receiver terminal at a moving speed of v, resulting in multipath effects and intersymbol interference, which degrades the system transmission performance.

[0034] Such as figure 2 and image 3 As shown, assuming that the length of the observation interval is L, through decision feedback, the received value of each subcarrier of the previous L OFDM symbols and its decision value can be effectively used to estimate the channel of each subcarrier of the currently received OFDM symbol, and then with The decision results of the M-length training sequence are combined in a weighted form and further equalized. Assuming that the i-th OFDM symbol is currently received, and i is any value, it is demodulated, assuming that the length of the o...

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Abstract

The invention discloses a visible light communication equalization method based on OFDM, by establishing a decision feedback link between MPSK/MQAM symbol decision and OFDM channel equalization, according to the magnitude of the moving speed of the mobile terminal, the decision result of each subcarrier symbol in the previously received OFDM symbol and the decision result of the received trainingsequence are fed back to the channel estimation process of the current OFDM symbol in a weighted manner, thus, the estimation accuracy and the equalization effect of the time-varying visible light channel are improved. At the same time, when the channel presents the characteristic of periodic change, the estimation result is stored in the database. When the receiver detects the periodic change, the database data are directly called, thereby simplifying the channel estimation process.

Description

technical field [0001] The invention belongs to the field of visible light communication, and in particular relates to channel estimation and equalization of a mobile visible light communication system. Background technique [0002] For illumination considerations, VLC systems usually contain multiple light sources. The optical signals transmitted by each light source transmitter at the same time reach the receiver through the direct line-of-sight link and the non-line-of-sight link reflected by the wall, the ground and other reflective surfaces. Due to the different delays of the arriving signal components, serious multipath effects will occur , reducing the system transmission performance. OFDM technology is widely used in visible light communication systems due to its strong resistance to multipath effects and high spectrum utilization. At the same time, OFDM uses single-tap frequency domain equalization to correct channel distortion, which greatly reduces the complexit...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B10/116H04L25/02H04L25/03H04L27/26
CPCH04B10/116H04L25/0202H04L25/03159H04L25/03267H04L27/2601
Inventor 陈健钟燕君由骁迪陈纾岩
Owner NANJING UNIV OF POSTS & TELECOMM
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