- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Deployment Issues and Performance Study in a Relay-Assisted Indoor Visible Light Communication System
摘要： This paper investigates the deployment issues and analyzes the performance of a relay-assisted indoor visible light communications (VLC) system with dc-biased optical orthogonal frequency division modulation (DCO-OFDM). The study considers two light sources in an office environment. One light source works as the information source and is located at the ceiling while the other one works as the relay terminal, which usually is a desk light or a floor light. We analyze the general blockage in a room, discuss the path loss of the VLC channel, and compare received signal power from a line of sight (LOS) link and a non-LOS link. The constraints on the relay height in order to achieve LOS connection are investigated. Simplified optimal power allocation under illumination and blockage constraints is proposed. Bit error rate performance is analyzed and the required signal power is derived for the relay-assisted DCO-OFDM VLC system. The study shows that in a relay-assisted VLC system, the blockage of source to destination link has trivial influence on the overall system performance if relays are properly deployed.
关键词： indoor,visible light communications (VLC),dc-biased optical orthogonal frequency division modulation (DCO-OFDM),relay,Channel model,power allocation
更新于2025-09-09 09:28:46
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[ACM Press the 2nd International Conference - Las Vegas, NV, USA (2018.08.27-2018.08.29)] Proceedings of the 2nd International Conference on Vision, Image and Signal Processing - ICVISP 2018 - Integrating Independent Component Analysis with Hopfield Recurrent Neural Network to Estimate the Channel of MIMO-OFDM System
摘要： Channel estimation is very important for MIMO-OFDM system, and because of electromagnetism complexity of circumstance in multipath communication environment and the sensitivity of OFDM modulation mode, which brings great difficulty for to solve the the channel estimation. In order difficulty of channel estimation problem in MIMO-OFDM system, this paper propose a semi-blind estimation method based on independent component analysis (ICA) algorithm combined with improved Hopfield recurrent neural network (HRNN) as a hybrid approach named ICA-HRNN. Then use the ICA-HRNN algorithm to estimate the channel information of MIMO-OFDM system. The simulation results show that, the ICA-HRNN algorithm can better adapt to the nonlinear characteristics of MIMO-OFDM system, and increase the estimation accuracy and the estimation speed, especially when the system has low SNR.
关键词： ICA-HRNN,MIMO-OFDM System,Channel Estimation,Improved HRNN,ICA
更新于2025-09-09 09:28:46
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[IEEE 2018 IFIP/IEEE International Conference on Performance Evaluation and Modeling in Wired and Wireless Networks (PEMWN) - Toulouse, France (2018.9.26-2018.9.28)] 2018 IFIP/IEEE International Conference on Performance Evaluation and Modeling in Wired and Wireless Networks (PEMWN) - SI-POF Transmission with OFDM and Sub-carrier Pairwise Coding
摘要： In this study, data transmission over step-index plastic optical fiber (SI-POF) is demonstrated using orthogonal frequency division multiplexing (OFDM) scheme with sub-carrier pairwise coding (PWC). To investigate the performance of OFDM with PWC, a simulation study is implemented with QPSK and 16-QAM format using the Gaussian theoretical frequency response for a 60 m SI-POF channel. For a data rate of 200 Mbps with QPSK-OFDM, the study shows that compared to equalization, PWC offers about 1.5 dB improvement at a bit-error-rate (BER) of 10-3. An experiment is then set-up with a 60 m SI-POF that uses an eye-safe resonant cavity light emitting diode (RC-LED) as the optical source. The experiment shows that at a bit rate of 200 Mbps with QPSK-OFDM, PWC offers a 1.82 dB improvement in SNR at a BER of 10-3. For the same data rate with 16-QAM-OFDM, PWC offers about 1.1 dB Q2-factor improvement for a modulation index of 0.8. The study therefore shows that PWC improves the BER performance of an SI-POF link that uses OFDM.
关键词： pairwise coding (PWC),plastic optical fiber (POF),equalization,Orthogonal frequency division modulation (OFDM)
更新于2025-09-09 09:28:46
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Performance analysis of direct detection optical OFDM systems
摘要： Orthogonal frequency division multiplexing (OFDM) is a multicarrier modulation technique, in which the data information is carried over many lower rate subcarriers. This technique is started effectively using in both line communication and wireless communication systems. This modulation technique has been actively started in the field of light wave communication called optical OFDM (OOFDM) system. OOFDM is a multicarrier modulation technique; it is used to overcome the problem of inter-symbol interference due to the chromatic dispersion and polarization mode dispersion of the fiber channel. In this paper, we have done simulation on direct detection optical OFDM (DDOOFDM) system with data rate of 10Gbps and measuring performance analysis of DDOOFDM system with respect to the received optical power and various full width half maximum value of the continuous wave laser source. This analysis is simulated using RSOFT Design Group OptSim Version-5.2.
关键词： Mach-Zehnder Modulator (MZM),Coherent Detection Optical OFDM (COOFDM),Optical Band Pass Filter (OBPF),Optical Single Sideband (OSSB),Full Width Half Maximum (FWHM),Direct Detection Optical OFDM (DDOOFDM)
更新于2025-09-04 15:30:14
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[IEEE 2018 10th International Conference on Communication Software and Networks (ICCSN) - Chengdu (2018.7.6-2018.7.9)] 2018 10th International Conference on Communication Software and Networks (ICCSN) - Pilot Power Optimization Based Channel Estimation Method for Optical OFDM/OQAM
摘要： Orthogonal frequency division multiplexing (OFDM) combined with offset quadrature amplitude modulation (OQAM) have become the hot research topic recently. OFDM/OQAM utilizes the specially designed filter bank with localization (TFL) property to promising time-frequency overcome the orthogonal condition for OFDM/OQAM only holds in the real field. Optical OFDM/OQAM systems faced with serious intrinsic imaginary interference (IMI) effect induced by chromatic dispersion (CD) and polarization mode dispersion (PMD), which decreased the transmission performance significantly. In this paper, we proposed a pilot power optimization based channel estimation method to improve the optical system OFDM/OQAM systems. The general pilot design criterion has been proposed in this paper, and numerous pilot structures reported in previous publications have been compared with the proposed method. As demonstrated in the simulation results, the pseudo pilot structures satisfying the proposed structure could obtain optimal pseudo pilot power, which could improve the system robustness against IMI effect and amplified spontaneous emission (ASE) evidently.
关键词： OFDM/OQAM,intrinsic imaginary interference,optical communication,channel estimation
更新于2025-09-04 15:30:14
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[IEEE 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) - Nantes (2018.9.24-2018.9.27)] 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) - Indoor Positioning Using OFDM-Based Visible Light Communication System
摘要： Precise indoor positioning is essential to support emerging applications of location aware mobile computing. Current positioning techniques that use signals transmitted in the Gigahertz region of radio-frequency spectrum do not provide highly accurate position estimates due to multipath propagation of signals. This paper proposes a novel positioning system which uses the entities of visible light communication (VLC) system as anchors and tags. Our technique scales with the number of tags and the VLC network provides both positioning and communication capabilities. The anchor points transmit the OFDM-based VLC signals synchronously, and we estimate the time differences of arrival between anchor points and tags using positioning reference signals embedded into the air-interface of the VLC system. Simulation results show that positioning accuracy of 10 cm or better is possible for over 95% of users if the sampling clock offset is better that 10 ppm, clock jitter is below 1 ps, and a bit resolution of at least 16 bits is available.
关键词： multipath propagation,OFDM,TDOA,visible light communication,indoor positioning
更新于2025-09-04 15:30:14
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Zero-Padded Conjugate Transmission to Cancel ICI in OFDM System
摘要： In OFDM (Orthogonal Frequency Division Multiplexing) to minimize effect of Inter-carrier interference the proposed technique Conjugate transmission with Zero padding and adaptive receiver is proposed in this research article. To transmit the signal according to proposed scheme, first regular OFDM signal is transmitted as a signal in the first path and conjugate signal of regular OFDM is transmitted using proposed algorithm in second path. Two consecutive symbols of the proposed OFDM signal is transmitter after padding Zeros between them to minimize the effect of inter-carrier interference for better time and frequency synchronization between transmitter and receiver signal. To adaptively update the frequency offset error receiver is designed with block least mean-squared algorithm (BLMS). BPSK, QPSK and 16-QAM modulation techniques are used and simulation results are carried out using MATLab software. Simulation results for proposed scheme are compared with regular OFDM system, Conjugate Cancellation (CC) and Phase Rotation Conjugate technique (PRCC) with reference to BER and simulation graphs shows that proposed scheme shows better BER rate performance as comparison to conventional techniques for AWGN wireless channel.
关键词： Block Least Mean-Squared (BLMS) Algorithm,Orthogonal Frequency Division Multiplexing (OFDM),Inter-Carrier Interference (ICI),Adaptive Receiver
更新于2025-09-04 15:30:14
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[IEEE 2017 International Conference on Optical Network Design and Modeling (ONDM) - Budapest (2017.5.15-2017.5.18)] 2017 International Conference on Optical Network Design and Modeling (ONDM) - A probabilistic approach for failure localization
摘要： This work considers the problem of fault localization in transparent optical networks. The aim is to localize single-link failures by utilizing statistical machine learning techniques trained on data that describe the network state upon current and past failure incidents. In particular, a Gaussian Process (GP) classi?er is trained on historical data extracted from the examined network, with the goal of modeling and predicting the failure probability of each link therein. To limit the set of suspect links for every failure incident, the proposed approach is complemented with the utilization of a Graph-Based Correlation heuristic. The proposed approach is tested on a dataset generated for an OFDM-based optical network, demonstrating that it achieves a high localization accuracy. The proposed scheme can be used by service providers for reducing the Mean-Time-To-Repair of the failure.
关键词： Graph-Based Correlation,OFDM,Gaussian Process,transparent optical networks,fault localization
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Broadband mm-wave OFDM communications in doubly selective channel: performance evaluation using measured mm-wave channel
摘要： In this work, we evaluate the performance of the broadband millimeter-wave (mm-wave) OFDM system in the presence of phase noise (PN) of phase-locked loop based oscillator and delay spread of measured mm-wave channel. It is shown, using Akaike’s information criterion, that the channel tap coefficients of the broadband mm-wave channel do not follow Gaussian distribution due to the broad bandwidth. It is also shown that, given a cyclic prefix (CP) length for a certain delay spread, an effective PN mitigation scheme enables a PN corrupted OFDM system to function with small subcarrier spacing and, therefore, small CP overhead, with only slight degradation of the error rate performance.
关键词： Mm-wave,phase noise,OFDM,propagation
更新于2025-09-04 15:30:14
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Enhanced Index Modulated OFDM Spread Spectrum
摘要： Index modulated OFDM spread spectrum (OFDM-IM-SS) is a recently proposed scheme, which transmits the additional bits (index bits) through the code domain. In this paper, we propose a novel variant of OFDM-IM-SS, called index modulated OFDM with in-phase/quadrature spread spectrum (OFDM-IM-SS-IQ), to increase the spectrum efficiency of OFDM-IM-SS. In OFDM-IM-SS-IQ, the transmitted symbols are divided into in-phase and quadrature parts, which are combined by the corresponding spreading codes selected by their respective index bits. A low complexity detection algorithm for OFDM-IM-SS-IQ is investigated to relieve the computational complexity of the optimal maximum-likelihood detection. A closed-form of the upper bound on the bit error rate is then derived to evaluate the error performance of OFDM-IM-SS-IQ. In addition, a diversity-enhancing scheme of OFDM-IM-SS, named index modulated OFDM spread spectrum enhancement (OFDM-IM-SS-E), is also designed to achieve a full diversity order. Computer simulation results validate the theoretical analysis and show that OFDM-IM-SS-IQ outperforms the conventional OFDM-IM-SS scheme. They also prove that the proposed OFDM-IM-SS-E obtains full diversity and achieves a better bit error rate performance than OFDM-IM-SS.
关键词： diversity,OFDM,index modulation,low complexity,spread spectrum
更新于2025-09-04 15:30:14