- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Subcarrier-Index Modulated Multicarrier Space-Time Shift Keying: Achievable Rate, Performance and Design Guidelines
摘要： Multicarrier (MC) space-time shift keying (STSK) relying on the concept of subcarrier-index modulated orthogonal frequency division multiplexing (SIM-OFDM) is proposed. In conventional MC-STSK system, the performance erosion of STSK in dispersive channels is mitigated by employing OFDM. The SIM-OFDM aided MC-STSK activates a specified limited number of subcarriers for transmitting the STSK codewords. The indices of the activated subcarriers provide additional multiplexing gain. A new receiver architecture, which uses the single-stream maximum-likelihood (ML) detector of STSK and the subcarrier activation principle of SIM-OFDM, is designed. A soft decision logarithmic likelihood ratio (LLR) based detector is also conceived. Helpful design guidelines are provided for the system. The achievable rate, complexity and performance of the system are analytically quantified and verified with the aid of numerical simulations. The system is capable of overcoming the impairments imposed by wideband channels, is benefited from index modulation as well as from STSK. The scheme exhibits an improved error performance compared to the classic OFDM-based STSK as a result of the more reliable detection of the subcarrier index bits.
关键词： Space-time shift keying (STSK),multiple-input multiple-output (MIMO),orthogonal frequency division multiplexing (OFDM),subcarrier index modulation
更新于2025-09-23 15:23:52
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Diffraction Focal Position and Vector Diffraction Theory for Micro Holographic Storage Systems
摘要： In this study, we proposed a method to determine the optimal focal position for micro-holographic storage systems, using vector diffraction theory; the theory provides exact solutions when the numerical aperture (NA) exceeds 0.6. The best diffraction focus was determined by the position and wavelength corresponding to minimal spherical aberration. The calculated refractive index modulation, polarization illumination, and boundary conditions at the interface of different media were analyzed. From the results of our analysis, we could confirm the size of micrograting as a function of NA and wavelength, based on vector diffraction theory, compared with scalar diffraction theory which defines the micrograting by . To demonstrate our analysis, we adapted an optical alignment method using a Twyman-Green interferometer, and could obtain good agreement between analysis and experimental results.
关键词： microholographic storage system,diffraction focus,vector diffraction theory,scalar diffraction theory,diffraction efficiency,refractive index modulation,interferogram,polarization
更新于2025-09-23 15:22:29
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Distributed Processing for Multi-Relay Assisted OFDM with Index Modulation
摘要： Orthogonal frequency-division multiplexing with index modulation (OFDM-IM) has become a high-profile modulation scheme for the fifth generation (5G) wireless communications, and thus been extended to multi-hop scenarios in order to improve the network coverage and energy efficiency. However, the extension of OFDM-IM to multi-relay cooperative networks is not trivial, since it is required that a complete OFDM block should be received and decoded as an entity in one node. This requirement prevents the employment of multiple relays to forward fragmented OFDM blocks on individual subcarriers. In this regard, we propose a distributed processing scheme for multi-relay assisted OFDM-IM, by which multiple relays are selected to forward signals in a per-subcarrier manner to provide optimal error performance for two-hop decode-and-forward (DF) OFDM-IM systems. Specifically, a single selected relay only needs to decode partial information carried on certain active subcarriers and forward just as for traditional OFDM systems without IM. After receiving all signals on active subcarriers forwarded by different relays, the destination can reconstruct the complete OFDM block and retrieve the full information. We analyze the average block error rate (BLER) and modulation capacity of the two-hop OFDM-IM system employing the proposed distributed DF protocol and verify the analysis by numerical simulations.
关键词： multi-carrier relay selection,decode-and-forward (DF) relaying,Orthogonal frequency-division multiplexing with index modulation (OFDM-IM),distributed system,distributed processing
更新于2025-09-23 15:22:29
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Experimental Demonstration of Subband Index Techniques for m-CAP in Short Range SI-POF Links
摘要： In this letter, novel spectrally-efficient subband index (SI) techniques have been developed for multiband carrierless amplitude and phase modulation (m-CAP). The subband index techniques transmit additional information bit on the index of the conventional m-CAP subbands. Experimental demonstrations are performed in a short range optical data link using step-index plastic optical fibre (SI-POF). The demonstrations show that the proposed techniques enable flexibility in design and significantly improve the power/spectral efficiency of the conventional m-CAP.
关键词： step-index plastic optical fibre (SI-POF),multiband carrierless amplitude phase modulation (m-CAP),index modulation,Optical communication
更新于2025-09-23 15:21:21
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SWIPT Schemes for Carrier Index Differential Chaos Shift Keying Modulation: A New Look at the Inactive Carriers
摘要： In this paper, two carrier index differential chaos shift keying with simultaneous wireless information and power transfer (CI-DCSK SWIPT) schemes, which integrate carrier index differential chaos shift keying (CI-DCSK) modulation with wireless power transfer, are proposed. In the proposed schemes, based on the transmission characteristics of index modulation (IM), the inactive carriers of CI-DCSK are exploited to delivery energy by transmitting random noise-like signals subjected to normal distribution. By applying time switching (TS) at the receiver, each frame time of the proposed schemes is divided into two intervals. Unlike usual TS-based systems, two intervals of the proposed schemes are related, where energy harvesting and decoding of the modulated bits are both operated in the second interval. Analytical bit error rate (BER) expressions over additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels of the two schemes are derived. The expression for the parameter ξ is also derived, which measures the probability of self-suf?ciency of these schemes. The impact of the dividing point of two intervals on BER performance of systems is also analysed and optimized. Since the energy on the inactive carriers is adjustable, the schemes are always self-sustainable in energy supply. To provide the best performance, the ratio of energy on the inactive carriers to that on the active carriers is optimized. Simulation results show that though performances of the proposed schemes are a little worse than CI-DCSK with the same spectral ef?ciency (SE), the proposed schemes are all self-sustainable.
关键词： SWIPT,DCSK,energy ef?ciency,Index modulation,detection,spectrum ef?ciency,self-sustainable
更新于2025-09-19 17:15:36
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Extended Spatial-Index LED Modulation for Optical MIMO-OFDM Wireless Communication
摘要： An efficient optical modulation technique for multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) visible light communication system is proposed in this paper. The proposed modulation technique is termed as extended spatial-index light-emitting diode (LED) modulation. In the proposed technique, the indices (the spatial domain) of the LEDs are exploited in a dynamic style to not only get rid of the optical OFDM time-domain (OFDMtd) shaping problem but also to expand the LED indices spatial modulation domain. The indices of the active LEDs in the proposed technique are changed from the two LEDs active situation to the situation where all or several LEDs are active. Moreover, within the selected active LED indices, the power weight distribution and the positions of the OFDM components are varied to expand the resultant spatial domain. Therefore, the proposed technique offers a considerable spectral efficiency improvement over the up-to-date LED index OFDM modulation schemes even with a lower number of LEDs. The key idea of the proposed technique is to maximize the LEDs’ indices spatial position (spatial domain) utilization, where both the power weight allocation and the positions of the complex OFDM time domain components are varying several times over the same active LED indices combination, which improve the optical system spectral efficiency. The simulation results asserted the superiority of the proposed technique, as it improves both the average bit error rate (ABER) and the achievable data rate (R) compared with existing up-to-date OFDM-LED index modulations with even lower computational complexity.
关键词： optical MIMO-OFDM,generalized led index modulation,OFDM-LED index modulation,visible light communication (VLC)
更新于2025-09-19 17:13:59
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Coherent Optical Orthogonal Frequency Division Multiplexing with Index Modulation
摘要： CO-OFDM with index modulation is proposed in this paper. Compared with the conventional CO-OFDM systems, the proposed scheme can improve spectral efficiency up to 6.25% with similar transmission performance.
关键词： Index modulation,Spectral efficiency
更新于2025-09-16 10:30:52
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Voltage-gated optics and plasmonics enabled by solid-state proton pumping
摘要： Devices with locally-addressable and dynamically tunable optical properties underpin emerging technologies such as high-resolution reflective displays and dynamic holography. The optical properties of metals such as Y and Mg can be reversibly switched by hydrogen loading, and hydrogen-switched mirrors and plasmonic devices have been realized, but challenges remain to achieve electrical, localized and reversible control. Here we report a nanoscale solid-state proton switch that allows for electrical control of optical properties through electrochemical hydrogen gating. We demonstrate the generality and versatility of this approach by realizing tunability of a range of device characteristics including transmittance, interference color, and plasmonic resonance. We further discover and exploit a giant modulation of the effective refractive index of the gate dielectric. The simple gate structure permits device thickness down to ~20 nanometers, which can enable device scaling into the deep subwavelength regime, and has potential applications in addressable plasmonic devices and reconfigurable metamaterials.
关键词： optical properties,solid-state proton pumping,refractive index modulation,hydrogen loading,electrochemical hydrogen gating,voltage-gated optics,plasmonics
更新于2025-09-12 10:27:22
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Compressed Sensing-Aided Index Modulation Improves Space-Time Shift Keying Assisted Millimeter-Wave Communications
摘要： In this treatise, we present the concept of Compressed-Sensing (CS)-aided Space-Time Shift Keying Index Modulation (STSK-IM), where a virtual domain Orthogonal Frequency Division Multiplexing (OFDM) symbol is divided into Na-sized blocks, which carry K STSK codewords over a specific combination of virtual-domain sub-carriers and then converted to the frequency domain with the aid of a CS matrix. We design the system for operation in the Milli-meter Wave (mmWave) frequency band. Furthermore, we amalgamate our soft-decision-aided scheme both with the concept of Coordinate-Interleaving (CI) as well as a Discrete Fourier Transform (DFT)-aided codebook design conceived for analogue beamforming, which is vitally important for mmWave systems. In the proposed system, the number of implicit bits conveyed by the activated sub-carrier Frequency Index (FI) is determined by the number of the available K to Na sub-carrier permutations. Hence, we propose two FI allocation techniques, namely the Distinct FI (DFI) and the Shared FI (SFI) based schemes, which strike a trade-off between the attainable sparsity level and the achievable capacity limit. We then introduce a reduced-complexity detection technique in order to mitigate the detection complexity to order of the optimum detector from O(Nc · (Q · L)K) to O(?Nc · (Q · L)K), where ?Nc ≤ Nc. We also formulate the Discrete-Input Continuous-Output Memoryless Channel (DCMC) capacity and invoke EXtrinsic Information Transfer (EXIT) charts for characterizing the achievable performance limit of the reduced-complexity aided detector. Finally, we analyze the BER performance of both the uncoded and of our coded CS-aided STSK-IM systems associated with both the optimum and the reduced-complexity detectors.
关键词： Spatial Modulation,Compressed Sensing,mmWave,Reduced Complexity detection,Millimeter-wave communications,Space-Time Shift Keying,channel coding,PSK,QAM,MIMO,Coordinate Interleave,Spatial modulation,5G,OFDM,Index modulation,wideband channel
更新于2025-09-11 14:15:04
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[IEEE 2018 International Conference on Machine Learning and Cybernetics (ICMLC) - Chengdu, China (2018.7.15-2018.7.18)] 2018 International Conference on Machine Learning and Cybernetics (ICMLC) - Image Quality Estimation Using Logarithmic Spread Transform Dither Modulation
摘要： As a pragmatic and novel application of digital watermarking, image quality estimation has been studied in recent years. In this paper, we propose a watermarking-based image quality evaluation scheme. The Logarithmic Spread Transform Dither Modulation is proposed based on the quantization index modulation and then applied to embed and extract the watermarks. The traditional objective metrics are employed to measure quality of images. We calculate the True Detection Rates (TDR) value to represent degradation of watermark. Considering that the embedded watermark and the watermarked image are distorted simultaneously, the image quality can be evaluated by matching the TDR value with a quality value on a pre-generated curve. Experimental results indicate that the proposed scheme provides a good image quality estimation result. The accuracy of the estimation keeps stabilization under different tested attacks, including JPEG compression, Gaussian noise addition and low-pass filtering.
关键词： True detection rates,Logarithmic spread transform dither modulation,Image quality estimation,Quantization index modulation
更新于2025-09-09 09:28:46