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CN-122001470-A - DEADO-OFDM system dimming and bit error rate collaborative optimization system and method

CN122001470ACN 122001470 ACN122001470 ACN 122001470ACN-122001470-A

Abstract

The invention discloses a DEADO-OFDM system dimming and error rate collaborative optimization system, which relates to the technical field of visible light communication, wherein a transmitting end signal is subjected to PAM modulation and carrier allocation, and then divided into two paths of IFHT conversion, cut-off processing and merging into ADO-OFDM and NADO-OFDM signals, the ADO-OFDM and NADO-OFDM signals are fed into a channel after offset is added and dimming is adapted, and a receiving end outputs a recovered carrier signal through a receiving pretreatment, frame branching and signal recovery module. The core optimization is that firstly, a transmitting end integrates a subcarrier domain cut-off noise self-compensation mechanism, secondly, discrete Hartley transformation is adopted to replace Fourier transformation, and thirdly, continuous dimming of 0% -100% is realized by dynamically adjusting the frame number ratio of ADO-OFDM and NADO-OFDM. The invention also discloses a DEADO-OFDM system dimming and bit error rate collaborative optimization method, which can realize DEADO-OFDM system dimming and bit error rate collaborative optimization, remarkably improve the frequency spectrum efficiency, and reduce the bit error rate to be at SNR=25dB And the low complexity, high spectral efficiency and flexible dimming are considered, and the multi-scene VLC application requirements are met.

Inventors

  • FENG MAN
  • LI MENGWEI
  • CHEN JINHUI

Assignees

  • 东南大学

Dates

Publication Date
20260508
Application Date
20260202

Claims (10)

  1. 1. A DEADO-OFDM system dimming and bit error rate collaborative optimization system is characterized by comprising a transmitting end and a receiving end; The transmitting terminal is used for sequentially carrying out pulse amplitude modulation PAM and carrier allocation on an initial signal, outputting an asymmetric amplitude limiting optical orthogonal frequency division multiplexing ACO-OFDM initial signal and a direct coupling optical orthogonal frequency division multiplexing DCO-OFDM initial signal, generating an intercepted ACO-OFDM signal and a negative asymmetric amplitude limiting optical orthogonal frequency division multiplexing NACO-OFDM signal by discrete Hartley transformation and interception operation on the ACO-OFDM initial signal, carrying out subcarrier domain noise self-compensation on the DCO-OFDM initial signal by interception noise of the intercepted ACO-OFDM signal, outputting the intercepted DCO-OFDM signal and the negative direct coupling optical orthogonal frequency division multiplexing NDCO-OFDM signal by discrete Hartley transformation and interception operation, then carrying out positive and negative combination on the intercepted ACO-OFDM signal and the DCO-OFDM signal, the intercepted NACO-OFDM signal and the NDCO-OFDM signal into an asymmetric direct current bias optical orthogonal frequency division multiplexing ADO-OFDM carrier signal and a negative asymmetric amplitude limiting direct current bias optical orthogonal frequency division multiplexing NADO-OFDM signal by the interception noise of the intercepted ACO-OFDM signal, and realizing continuous transmission of a dimming channel by adjusting the ADO-NADO; the receiving end is used for judging the frame number of the channel transmission signal, recovering ADO-OFDM carrier wave and NADO-OFDM carrier wave signals, combining the ADO-OFDM carrier wave and NADO-OFDM carrier wave signals after carrying out discrete Hartley inverse transformation to obtain a combined signal, namely a signal to be recovered, and recovering and outputting the carrier wave signal from the signal to be recovered by adopting a DEADO-OFDM carrier wave recovery signal method.
  2. 2. The system of claim 1, wherein the transmitting end comprises a PAM modulation and carrier allocation module, ACO-OFDM and NACO-OFDM signal processing modules, DCO-OFDM and NDCO-OFDM signal processing modules, a signal combining and dimming module, and a transmitting processing module; the PAM modulation and carrier allocation module is used for outputting ACO-OFDM initial signals and DCO-OFDM initial signals after PAM modulation of input signals, transmitting the ACO-OFDM initial signals to the ACO-OFDM and NACO-OFDM signal processing modules, and transmitting the DCO-OFDM initial signals to the DCO-OFDM and NDCO-OFDM signal processing modules; The ACO-OFDM and NACO-OFDM signal processing module is used for carrying out discrete Hartley inverse transformation and truncation on an ACO-OFDM initial signal, and outputting the truncated ACO-OFDM signal and the truncated NACO-OFDM signal to the DCO-OFDM and NDCO-OFDM signal processing module and the signal merging and dimming module; The DCO-OFDM and NDCO-OFDM signal processing module is used for performing truncated noise self-compensation on a DCO-OFDM initial signal by using the truncated ACO-OFDM signal and NACO-OFDM signal through discrete Hartley transformation, and outputting the truncated DCO-OFDM signal and NDCO-OFDM signal to the signal merging and dimming module through discrete Hartley inverse transformation and positive and negative truncation; The signal merging and dimming module is used for merging the truncated ACO-OFDM and the truncated DCO-OFDM to output ADO-OFDM signals, merging the truncated NACO-OFDM and the truncated NDCO-OFDM to output NADO-OFDM signals, adding direct current offset to NADO-OFDM signals, and finally adjusting the frame ratio of the ADO-OFDM and NADO-OFDM carrier signals to adapt to dimming requirements and outputting DEADO-OFDM signals to the transmitting processing module; And the transmitting processing module is used for generating a channel transmission signal and sending the channel transmission signal into a visible light channel after carrying out parallel-serial conversion and cyclic prefix adding processing on DEADO-OFDM signals.
  3. 3. The system for collaborative optimization of dimming and error rate of DEADO-OFDM system according to claim 1, wherein the receiving end comprises a receiving preprocessing module, a frame branching module and a signal recovery module, The receiving preprocessing module is used for carrying out basic preprocessing on the received channel transmission signals, the basic preprocessing comprises cyclic prefix removal and serial-parallel conversion, and a signal to be frame separated is output to the frame branching module; The frame branching module is used for distinguishing ADO-OFDM frames from NADO-OFDM frames in the signals to be separated according to a preset threshold value, removing direct current offset of signals corresponding to the ADO-OFDM frames and the NADO-OFDM frames, and outputting the signals to be recovered to the signal recovery module; And the signal recovery module is used for carrying out discrete Hartley transformation, subcarrier combination, PAM demodulation and LDPC decoding on the signal to be recovered and outputting a recovered DEADO-OFDM carrier signal.
  4. 4. The system for collaborative optimization of dimming and error rate for a DEADO-OFDM system as set forth in claim 2, wherein, The subcarrier domain cut-off noise self-compensation mechanism of the DCO-OFDM and NDCO-OFDM signal processing modules comprises the steps of carrying out discrete Hartley transformation on ACO-OFDM signals once, extracting cut-off noise characteristics of the cut-off ACO-OFDM signals, mapping the cut-off noise characteristics to a time domain, and overlapping the cut-off noise characteristics of the time domain into time domain waveforms of the DCO-OFDM signals to realize real-time cancellation of cut-off noise.
  5. 5. A DEADO-OFDM system dimming and bit error rate co-optimizing system as claimed in claim 3, wherein the discrete hartley transform comprises IFHT transform at the transmitting end and FHT transform at the receiving end, both using pure real number operation.
  6. 6. The DEADO-OFDM system dimming and bit error rate collaborative optimization system according to claim 3, wherein odd-numbered carrier data of a signal to be recovered outputted by the frame branching module is extracted, odd-numbered carrier data is recorded as an ACO-OFDM signal component, even-numbered carrier data is recorded as a DCO-OFDM signal component, the recovery process of the ACO-OFDM signal is to use twice of the ACO-OFDM signal component as a reconstructed ACO-OFDM signal, the recovery process of the DCO-OFDM signal is to perform discrete hart inverse transform IFHT on the ACO-OFDM signal component and the DCO-OFDM signal component respectively, extract a truncated noise component of the ACO-OFDM signal component passing IFHT, subtract twice of the truncated noise component from the DCO-OFDM signal component passing IFHT, perform discrete hart transform to obtain a reconstructed DCO-OFDM signal, combine the reconstructed ACO-OFDM signal and the reconstructed DCO-OFDM signal to obtain a reconstructed ADO-OFDM signal, and perform demodulation and LDPC decoding on the reconstructed ADO-OFDM signal to recover DEADO-OFDM signal.
  7. 7. The DEADO-OFDM system dimming and bit error rate collaborative optimization system according to claim 1 is characterized in that the adjusting range of continuous dimming is 0% -100%, and specifically comprises three stages, 0% -20% of low dimming adopts full ADO-OFDM signal transmission, 20% -80% of medium dimming adopts ADO-OFDM signal and NADO-OFDM signal frame number mixed transmission, and 80% -100% of high dimming adopts full NADO-OFDM signal transmission.
  8. 8. The system of claim 3, wherein the sub-carrier combining of the signal recovery module combines the reconstructed DCO-OFDM signal after discrete Hartley transform with the ACO-OFDM signal reconstructed by the signal recovery module to obtain a reconstructed ADO-OFDM signal, and then performs the next operation of the reconstructed ADO-OFDM signal in combination with PAM demodulation and LDPC decoding demodulation.
  9. 9. A DEADO-OFDM system dimming and bit error rate co-optimizing system as claimed in claim 3, wherein the modulation order of PAM modulation is dynamically configured to 2PAM, 4PAM or 8PAM according to different spectral efficiency requirements.
  10. 10. A method for a DEADO-OFDM system dimming and bit error rate co-optimization system based on claim 1, comprising: Step 1, after a transmitting end is started, an input signal is subjected to PAM modulation by a PAM modulation and carrier distribution module and is distributed to an ACO-OFDM and NACO-OFDM signal processing module and a DCO-OFDM and NDCO-OFDM signal processing module; Step 2, an ACO-OFDM and NACO-OFDM signal processing module executes discrete Hartley inverse transformation and positive and negative truncation on an ACO-OFDM initial signal to generate a truncated ACO-OFDM signal and a truncated NACO-OFDM signal, and a DCO-OFDM and NDCO-OFDM signal processing module executes subcarrier domain truncated noise self-compensation, discrete Hartley inverse transformation and positive and negative truncation on the DCO-OFDM initial signal to generate a truncated DCO-OFDM signal and a truncated NDCO-OFDM signal; Step 3, the signal merging and dimming adaptation module merges the truncated ACO-OFDM signal and the truncated DCO-OFDM signal to obtain an ADO-OFDM signal, merges the truncated NACO-OFDM signal and the truncated NDCO-OFDM signal, adds IH offset to obtain a NADO-OFDM signal, adjusts the frame ratio of the ADO-OFDM signal to the NADO-OFDM signal, and merges the signals to obtain a DEADO-OFDM signal; step 4, the emission processing module sequentially executes parallel-serial conversion and cyclic prefix addition on DEADO-OFDM signals obtained after combination to obtain channel transmission signals, and the channel transmission signals are sent into a visible light channel; Step 5, a receiving preprocessing module of the receiving end executes cyclic prefix removal and serial-parallel conversion on the channel transmission signal received from the visible light channel; Step 6, the frame branching module judges ADO-OFDM signals and NADO-OFDM signal frame numbers through a threshold Ad, and removes IL and IH offset respectively to obtain signals to be recovered; And 7, the signal recovery module performs discrete Hartley transformation, subcarrier combination, PAM demodulation and LDPC decoding on the signal to be recovered by utilizing a DEADO-OFDM carrier recovery signal method, and outputs a recovered DEADO-OFDM carrier signal.

Description

DEADO-OFDM system dimming and bit error rate collaborative optimization system and method Technical Field The invention relates to the technical field of Visible Light Communication (VLC), in particular to a dimming and bit error rate collaborative optimization system and method of a dimming enhanced type asymmetric amplitude limiting direct current bias light orthogonal frequency division multiplexing DEADO-OFDM system. Background The indoor wireless communication and illumination integration requirements are increasingly improved, and Visible Light Communication (VLC) becomes a research hot spot by virtue of rich spectrum resources, no electromagnetic interference and the like. The direct coupling optical orthogonal frequency division multiplexing DCO-OFDM and the asymmetric limiting optical orthogonal frequency division multiplexing ACO-OFDM are core modulation technology in VLC, the enhanced ADO-OFDM (eADO-OFDM) is used for adaptively adjusting the number of subcarriers of the DCO-OFDM and the ACO-OFDM, flexibility, spectral efficiency and multipath interference resistance are considered, and on the basis, a tunable optical enhanced ADO-OFDM (DEADO-OFDM) system is proposed to meet the requirements of light modulation control. The conventional DEADO-OFDM related scheme has obvious technical bottlenecks that firstly, the dimming is required to rely on direct current bias, the frequency spectrum efficiency is reduced, inter-carrier interference is caused by carrier cut-off noise, and the error rate is increased, secondly, in order to balance the dimming and the error rate, the conventional scheme usually adopts a complex frequency domain predistortion or multi-carrier architecture, the complex operation characteristics of Fourier transformation of a conventional OFDM system are overlapped, the complexity of the system is obviously increased, a low-computation-force terminal is difficult to adapt, thirdly, the nonlinear power amplifier is easy to cause signal quality degradation, the conventional predistortion processing technology is difficult to realize effective performance compensation on the premise of low complexity, and finally the practical application requirement of 'low complexity-high spectral efficiency-continuous dimming' cannot be considered. Disclosure of Invention The invention aims to solve the technical problem of overcoming the defects of the prior art and providing a DEADO-OFDM system dimming and bit error rate collaborative optimization system and method, so as to solve the problem that the traditional visible light communication and the like are difficult to realize balance among low complexity, high spectral efficiency and continuous dimming, and realize an indoor visible light communication scene which is suitable for collaborative requirements on communication complexity, spectral efficiency, dimming flexibility and bit error rate performance. The invention adopts the following technical scheme for solving the technical problems: The invention provides a DEADO-OFDM system dimming and bit error rate collaborative optimization system, which comprises a transmitting end and a receiving end; The transmitting terminal is used for sequentially carrying out pulse amplitude modulation PAM and carrier allocation on an initial signal, outputting an asymmetric amplitude limiting optical orthogonal frequency division multiplexing ACO-OFDM initial signal and a direct coupling optical orthogonal frequency division multiplexing DCO-OFDM initial signal, generating an intercepted ACO-OFDM signal and a negative asymmetric amplitude limiting optical orthogonal frequency division multiplexing NACO-OFDM signal by discrete Hartley transformation and interception operation on the ACO-OFDM initial signal, carrying out subcarrier domain noise self-compensation on the DCO-OFDM initial signal by interception noise of the intercepted ACO-OFDM signal, outputting the intercepted DCO-OFDM signal and the negative direct coupling optical orthogonal frequency division multiplexing NDCO-OFDM signal by discrete Hartley transformation and interception operation, then carrying out positive and negative combination on the intercepted ACO-OFDM signal and the DCO-OFDM signal, the intercepted NACO-OFDM signal and the NDCO-OFDM signal into an asymmetric direct current bias optical orthogonal frequency division multiplexing ADO-OFDM carrier signal and a negative asymmetric amplitude limiting direct current bias optical orthogonal frequency division multiplexing NADO-OFDM signal by the interception noise of the intercepted ACO-OFDM signal, and realizing continuous transmission of a dimming channel by adjusting the ADO-NADO; the receiving end is used for judging the frame number of the channel transmission signal, recovering ADO-OFDM carrier wave and NADO-OFDM carrier wave signals, combining the ADO-OFDM carrier wave and NADO-OFDM carrier wave signals after carrying out discrete Hartley inverse transformation to obtain a combin