Baseband Signal Research Articles

Liner multimode fibers with high distributed optical amplification system based high efficient quadrature modulation system for reliable high capacity local area network

Abstract This paper clarified the liner multimode fibers with high optical amplification system based high efficient quadrature modulation system for high capacity local area optical networks. The clarified the lighted QPSK transmitter system based linear multimode fiber profile is clarified under modal bandwidth effects. The optimum power variations are studied with spectral base band wavelength variations for various modal bandwidths based linear multimode fiber. Optimum power is clarified with time variations for various modal bandwidths based linear multimode fiber. Total power for 1500 and 1700 MHz km modal bandwidth is demonstrated based linear multimode fiber. The Max-Min signal base band amplitude based QAM pulse generator is clarified after photo-detector by using electrical constellation visualizer. The optimum Q Factor form with Min BER is demonstrated after photo-detector for 1300, 1500, and 1700 MHz km modal bandwidth based linear multimode fiber. The base band lighted SNR is clarified and simulated with the modal bandwidth variations based linear multimode fiber. Optimum Q form factor through photo-detector is demonstrated with the modal bandwidth variations based linear multimode fiber. The electrical SNR through photo-detector is studied and simulated with the modal bandwidth variations based linear multimode fiber.

Self-Biased Magneto-Electric Antenna for Very-Low-Frequency Communications: Exploiting Magnetization Grading and Asymmetric Structure-Induced Resonance.

VLF magneto-electric (ME) antennas have gained attention for their compact size and high radiation efficiency in lossy conductive environments. However, the need for a large DC magnetic field bias presents challenges for miniaturization, limiting portability. This study introduces a self-biased ME antenna with an asymmetric design using two magneto materials, inducing a magnetization grading effect that reduces the resonant frequency during bending. Operating principles are explored, and performance parameters, including the radiation mechanism, intensity and driving power, are experimentally assessed. Leveraging its excellent direct and converse magneto-electric effect, the antenna proves adept at serving as both a transmitter and a receiver. The results indicate that, at 2.09 mW and a frequency of 24.47 kHz, the antenna has the potential to achieve a 2.44 pT magnetic flux density at a 3 m distance. A custom modulation-demodulation circuit is employed, applying 2ASK and 2PSK to validate communication capability at baseband signals of 10 Hz and 100 Hz. This approach offers a practical strategy for the lightweight and compact design of VLF communication systems.

Simultaneous detection of multi-channel signals in MHz bandwidth using nitrogen-vacancy centers in a diamond.

In this paper, we propose a method for simultaneously recovering multiple radio wave signals based on nitrogen-vacancy (NV) centers in diamond combining optically detected magnetic resonance (ODMR) spectrum. A controlled magnetic field gradient applied to the laser excitation area on the surface of diamond widens the detectable ODMR bandwidth to 200 MHz. Three different frequency-modulated (FM) signals with distinct carrier frequencies falling within the resonance frequency range are received and demodulated in real-time. Subsequently, the FM signal reception capability of this system is further investigated by measuring baseband signal frequencies ranging from 0.1 Hz to 200 Hz and adjusting the carrier power within a dynamic range from -10 dBm to 30 dBm. This proposal, which accomplishes multi-channel demodulation using a compact and single device, has potential applications in fields such as wireless communication, radar and navigation.

A wideband low power RF Receiver Front-End for Internet-of-Things applications

This paper presents a broadband RF receiver front-end circuit that offers advantages in both area and power consumption. The design features an innovative dual-path noise-canceling Low-Noise Amplifier (LNA) circuit, achieving impedance matching and balun functionality without the need for on-chip inductors. The RF receiver front-end circuit comprises a I and Q doublebalanced quadrature passive mixers and an 25% duty-cycle LO generator. The circuit’s broadband characteristics enable it to operate across a wide range of frequency bands. It is implemented using a 65 nm CMOS process. The core circuit, including both RF and baseband signal paths, consumes a mere 12 mW of power. Test results demonstrate that the RF receiver front-end circuit achieves a conversion gain of 35–40 dB, a noise figure (NF) below 4.8 dB, and a minimum third-order intercept point (IIP3) exceeding −6.8 dBm over the 0.1–3.1 GHz frequency range. The chip’s overall footprint is compact at 0.9 mm2, with the entire RF signal path powered by a 1 V supply, offering clear advantages in terms of compactness and low power consumption.

Deep Learning Equalizer Connected with Viterbi-Viterbi Algorithm for PAM D-Band Radio over Fiber Link.

D-band (110-170 GHz) has been regarded as a potential candidate for the future 6G wireless network because of its large available bandwidth. At present, the lack of electrical amplifiers operating in the high frequency band and the strong nonlinear effect, i.e., the D-band, are still important problems. Therefore, effective methods to mitigate the nonlinear issue resulting from the ROF link are indispensable, among of which machine learning is considered the most effective paradigm to model the nonlinear behavior due to its nonlinear active function and structure. In order to reduce the computation amount and burden, a novel deep learning neural network equalizer connected with typical mathematical frequency offset estimation (FOE) and carrier phase recovery (CPR) algorithms is proposed. We implement D-band 45 Gbaud PAM-4 and 20 Gbaud PAM-8 ROF transmission simulations, and the simulation results show that the real value neural network (RVNN) equalizer connected with the Viterbi-Viterbi algorithm exhibits better compensation ability for nonlinear impairment, especially when dealing with serious inter-symbol interference and nonlinear effects. In our experiment, we employ coherent detection to further improve the receiver sensitivity, so a complex baseband signal after down conversion at the receiver is inherently produced. In this scenario, the complex value neural network (CVNN) and RVNN equalizer connected with the Viterbi-Viterbi algorithm have better BER performance with an error rate lower than the HD-FEC threshold of 3.8 × 10-3.

Practical Waveform-to-Energy Harvesting Model and Transmit Waveform Optimization for RF Wireless Power Transfer Systems

The received radio-frequency (RF) power in far-field RF wireless power transfer (WPT)—with or without simultaneous information transfer—is minuscule due to large propagation loss in wireless media. In such scenarios, adapting to the receiver characteristics by transmit waveform optimization is essential for maximizing the harvested direct current (dc) and, thus, the end-to-end efficiency of an RF WPT system. The receiver efficiency in RF WPT is governed by the RF-to-dc efficiency of the rectifier as well as the impedance mismatch at the antenna and load. In this article, we study the receiver efficiency for any fixed load and, subsequently, present a novel rectifier model that relates the average harvested dc power to the distribution, that is, the histogram, of the instantaneous power levels of the RF signal’s envelope over time. The proposed waveform-to-energy harvesting (EH) model enables us to anticipate the average harvested dc power for any waveform, including communication signals as well, given the knowledge of the power-level distribution. Consequently, we conduct rigorous waveform optimization to maximize the average harvested dc power and determine the digital baseband signal at the transmitter that does so, namely prove that a pulsed tone at appropriate frequency is optimal for RF WPT. We present a multiband test-bed for determining the receiver efficiency for any digital baseband waveform. The efficacy of the proposed model is corroborated through experiments as well as simulations, which confirm that it is operational as well as accurate in practice and that single-sine pulses yield higher efficiency than basic multisine waveforms, while a pulsed phase shift keying (PSK) is preferable for simultaneous wireless information and power transfer (SWIPT).

Design and Implementation of a Transmitter for IR-UWB Standard

In wireless communication, the Ultrawide Band (UWB) is a technique for achieving a higher data rate, low power consumption, and less complexity. Impulse Radio - Ultra-Wide Band (IR-UWB) uses the baseband signal technique, reducing circuit complexity and power consumption. This work proposes an IR-UWB transmitter block with low power and tunable bandwidth that meets the UWB regulations of LRP (Low-Rate Pulse) UWB. The transmitter proposed uses a time-interleaved architecture using 0.18um CMOS technology using Cadence Virtuoso, which consists of On Off Keying (OOK) Circuit for the four stages of a pulse generator that operates in 6.17GHz-9.10GHz. The width of the pulse is between 0.096ns to 0.162ns using a current steering inverter. The proposed transmitter block has an output swing of 30 mV at 1MHz input Pulse Repetition Frequency (PRF) and a maximum PRF of 1GHz, at a 1GHz pulse rate, the power consumption was measured to be 8.3 mW.

High modulation laser systems integrated with hybrid pulse generators for high speed fiber transmission systems

Abstract This study has simulated the high modulation laser systems integrated with hybrid pulse generators for high speed fiber transmission systems. The directly modulated laser with raised cosine/Gaussian pulse generators are employed for ultra-high data rates for modified multi band range applications. The total estimated light power after fiber cable system is demonstrated based on electro-absorption, phase, and single drive MZM measured modulators. The light base band signal and noise signal configuration is clarified after fiber cable system based on various proposed modulators. The degree of signal polarization configuration is studied after fiber cable system based on various modulators. Signal power level with Q, BER, signal eye height, and the total estimated electrical modulated signal power are evaluated after receiver system after receiver side based on proposed modulators.

Joint Resource Allocation in TWDM-PON-Enabled Cell-Free mMIMO System

Cell-free massive multiple input multiple outputs (CF-mMIMO) is considered a promising technology for sixth-generation (6G) telecommunication systems. In the CF-mMIMO system, an extensive array of distributed small base stations (BSs) is deployed across the network, which enables us to facilitate seamless collaboration among BSs. To achieve this goal, the baseband signal from these BSs needs to be transmitted to a central server via fronthaul networks. Due to the large number of BSs, the data that needs to be transmitted is usually huge, which brings severe requirements on fronthaul networks. Time and wavelength division multiplexed passive optical networks (TWDM-PON) can be a potential solution for CF-mMIMO fronthaul due to their large capacity and high flexibility. However, how to efficiently allocate both optical and wireless resources in a TWDM-PON-enabled CF-mMIMO system is still a problem to be addressed. This paper proposes a joint scheduling method of wavelength, antenna, radio unit (RU), and radio resource block (RB) resources in the TWDM-PON-enabled CF-mMIMO system. Furthermore, an integer linear programming (ILP) model for joint resource allocation is proposed to minimize the fronthaul resource occupancy, thereby increasing network scalability. Considering the complexity of the ILP model, two heuristic algorithms are also presented to solve this model. We compare the ILP with heuristic algorithms under different scenarios. Simulation results show that the proposed algorithm can reduce the fronthaul resource occupancy to improve the network scalability of the CF-mMIMO system.

High efficiency coupling fibers with different types of photo detectors for the management of noise multiplication and efficient bandwidth

Abstract This work has clarified the high efficiency coupling fibers with different types of photo detectors for the management of noise multiplication and efficient bandwidth. As well as the study of the base band signal to noise base band form ratios are clarified with EDFA base band amplifier length variations. Max Q form factor with EDFA amplifier base band length variations is also demonstrated. The optimum base band electrical signal form power is simulated with EDFA base band amplifier length variations. The simulative study of Ge and InGaAs PIN photo-detectors performance evaluation are studied in the presence of the soliton transmission fiber systems. The dispersion management by the soliton technique to reach the value around zero. The max base band signal power form is clarified versus time based Ge and InGaAs PIN photo-detectors. Total base band electrical power form based Ge and InGaAs PIN photo-detectors are demonstrated. Max signal base form power amplitude band is simulated with the spectral base band frequency based Ge and InGaAs PIN photo-detectors. The max signal base form power amplitude band is studied versus time based Ge PIN photo-detectors.

Reverse polarity optical Orthogonal frequency Division Multiplexing for High-Speed visible light communications system

The radio frequency spectrum, which has been steadily getting smaller, is under pressure from growing cellular data traffic. A more dependable communication channel is required. To setup the communication medium, VLC uses LED illumination. In order to increase network throughput, the goal of this study is to analyze and model signal conditioning techniques in the visible spectrum. VLC technology offers synchronized illumination of LED lamps as well as wireless broadband connectivity. Using the real-valued O-OFDM baseband signal, optical orthogonal frequency division multiplexing (O-OFDM) offers a viable modulation option for very-low-bit-rate (VLC) systems to modulate the optical carrier's instantaneous power to attain gigabit data rates. However, one important design difficulty preventing VLC from being commercialized is how to combine industry-favored pulse width modulation (PWM) dimming technology while retaining a dependable, broadband connection. In this paper, Reverse Polarity optical orthogonal frequency division multiplexing (RPO-OFDM) is proposed as a new signal format for combining the fast O-OFDM contact signal with the comparatively slow PWM dimming signal, as both signals contribute to the illuminative brightness of the LED. The average SNR, additional testing demonstrates that the suggested method outperforms the Asymmetrically clipped optical OFDM (ACO), Optimized Flipped Optical (OFO) and DC biased optical OFDM (DCO), and algorithms in similar operating conditions.

Efficient employment of VCSEL light sources in high speed dispersion compensation system

Abstract This paper demonstrated the efficient employment of vertical cavity surface emitting laser (VCSEL) light sources in high speed dispersion compensation systems. VCSEL are compared with CW laser and distributed feedback laser in the modulated light output power, signal quality factor and minimum data error rates through the fiber system. Light signal base band modulated power is clarified with spectral frequencies after LiNb MZ modulators. Light signal base band modulated amplitude is simulated against base band time frequencies after LiNb MZ modulators. The total light signal index base band modulated power/amplitude value is estimated after LiNb MZ modulators for various light sources. The light signal base band modulated power is demonstrated with both spectral frequencies and time interval after fiber loop control length with compensation system. Total light signal index base band modulated power/amplitude value is estimated numerically after fiber loop control length with compensation system. The modulated electronic signal base band modulated power is indicated with spectral frequencies after PIN receiver. The light signal base band modulated amplitude is studied clearly against base band time frequencies after PIN receiver. The signal quality factor, BER, and modulated lighted output power are clarified and sketched against fiber system lengths for various light sources.

Comparative study for performance efficiency of conventional optical transmitter with spatial optical transmitter through CWDM fiber system

Abstract This paper presents the comparative study for performance efficiency of conventional optical transmitter with spatial optical transmitter through coarse wavelength division multiplexed fiber system. The spatial light source mode polar and rectangular configuration are clarified in x directions. The lighted power signal through CWDM fiber system is simulated and measured with the use of conventional and spatial light transmitters. The lighted base band signal through CWDM fiber system is clarified with the use of conventional and spatial light transmitters. The lighted base band signal with spectral wavelength through CWDM fiber system is simulated with the use of conventional and spatial light transmitters. The Q base band signal quality factor and bit error signal rates are studied in the same configuration after receiver photodiode system with the use of conventional and spatial light transmitters.

Continuous wave light sources with various optical modulators for signal quality optical fiber systems enhancement

Abstract This study clarified the simulation study of the continuous wave light sources with various optical modulators for signal quality optical fiber systems enhancement. The lighted signal power spectrum is measured and tested with various optical modulators after fiber media system. Also the lighted base band modulated signal power value is demonstrated with different light modulators after fiber media system of the reach up to 10 km. The electrical modulated base band signal power value is clarified with various light modulators after receiver PIN system. Moreover, the electrical modulated signal base band power amplitude spectrum quality and data error system rate values are numerically clarified and measured with different light modulators after receiver PIN system. The electro-light modulators that are used namely amplitude, phase, frequency modulators and Mach–Zehnder modulator (MZM).

Attentive Siamese Networks for Automatic Modulation Classification Based on Multitiming Constellation Diagrams.

Automatic modulation classification (AMC) is an essential part in a cognitive radio receiver. Benefited from the discriminative constellation characteristics among most modulations, AMC methods based on constellation diagrams usually achieve pleasant performance. However, in noncooperation communication systems, constellation diagrams expressing modulations explicitly are difficult to obtain via blind symbol timing synchronization, especially in complicated wireless channels. Therefore, this article proposes a novel constellation diagram-based AMC architecture called attentive Siamese networks (ASNs) by considering multitiming constellation diagrams (MCDs) and selecting the proper symbol timings at the feature level, which is a more robust way than the conventional signal-level symbol timing synchronization. In detail, convolutional neural networks sharing the same parameters first extract deep feature vectors for MCDs. Then, an attention inference module weights all the deep feature vectors. Finally, AMC is realized based on the weighted feature vectors. Moreover, the ASN architecture can be trained end-to-end. Comparing with the state-of-the-art methods that take diverse representations of received baseband signals as input, experimental results based on the RadioML 2018.01A dataset and non-Gaussian noise dataset demonstrate that ASN achieves a remarkable improvement, whose classification accuracy goes over 99% when the signal-to-noise ratio (SNR) > 10 dB.

Peak Cancellation Method With IIR Filters and Its FPGA Implementation

To improve the efficiency of power amplifiers (PA) in communication transmitters, peak cancellation (PC) in the time domain is often implemented on a Field-programmable gate array (FPGA) to reduce the peak-to-average power ratio (PAPR) of the baseband signals. However, to reduce the out-of-band radiation, the existing techniques tend to use high-order finite impulse response (FIR) filters, which increases the input-to-output delay and resource consumption of FPGA. To address this issue, a PC method with the infinite impulse response (IIR) filter is proposed in this brief. The design criteria of the IIR filter for PC is given. The FPGA implementation scheme and resource optimization are discussed. To verify the performance of the proposed method, MATLAB simulation and FPGA implementation are made with a 5G NR signal. The comparison with the state-of-the-art PC methods shows that the proposed technique can reduce the total time delay greatly, with good PC performance and low resource consumption.

Secure transmission for IoT wireless energy-carrying communication systems.

The wireless energy-carrying communication method for the Internet of Things (IoT) presents several difficulties for information security such as eavesdropping or data loss. To solve these issues, this paper presents a new secure transmission method for IoT wireless energy-carrying communication systems. In this method, first the secret message is turned into a word, delivered to the intended recipient and unlawful listener, respectively, and the received message is characterized as an entropy function. The message is iteratively solved using the block coordinate descent technique, and for each iteration, a digital baseband signal containing the receiver's secret message symbol and the matching beamforming vector is delivered. By concurrently optimizing the transmit beamforming vector, the noise covariance matrix, and the receiver power allocation factor based on a design that complies with the security rate and energy acquisition limitations for each receiver, the overall system transmit power is reduced. The Lagrangian method is used to solve the secure transmission problem of the communication system based on an iterative block coordinate descent algorithm, as well as to change the nonconvex problem into a convex problem and precisely derive the upper and lower bounds of the original transmission problem. In comparison to the conventional policy transmission scheme, the experimental results demonstrate that the DIPS (Digital Image Processing System) scheme can increase the STP (Signaling Transfer Point) by approximately 34.16 percent in the eavesdropper independent eavesdropping and joint eavesdropping scenarios. The usefulness of the secure transmission strategy for wireless energy-carrying communication systems is confirmed by this investigation.

Real-Time Discrete Fractional Fourier Transform Using Metamaterial Coupled Lines Network

Discrete fractional Fourier transforms (DFrFTs) are universal mathematical tools in signal processing, communications, and microwave sensing. Despite the excessive applications of DFrFT, the implementation of corresponding fractional orders in the baseband signal often leads to bulky, power-hungry, and high-latency systems. In this article, we present a passive metamaterial coupled lines network (MCLN) that performs the analog DFrFT in real-time at microwave frequencies. The proposed MCLN consists of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$M$</tex-math> </inline-formula> parallel microstrip transmission lines (TLs) in which adjacent TLs are loaded with interdigital capacitors to enhance the coupling level. We show that with the proper design of the coupling coefficients between adjacent channels, the MCLN can perform an M-point DFrFT of an arbitrary fractional order that can be designed through the length of the network. In the context of real-time signal processing for the realization of DFrFT, we design, model, simulate, and implement a 16 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 16 MCLN and experimentally demonstrate the performance of the proposed structure. The proposed innovative approach is versatile and is capable to be used in various applications where DFrFT is an essential tool. The proposed design scheme based on MCLN is scalable across the frequency spectrum and can be applied to the millimeter and submillimeter wave systems.

A 60Mb/s -64dBm Body Channel Communication Transceiver Utilizing Manchester Code.

Body channel communication (BCC) which uses the human body as the communication channel has shown better energy efficiency and security compared with air channel communication. This article presents a simple, stable, and high transfer rate BCC technique using Manchester encoding, capacitive termination, and digital signal transfer operation. Manchester encoding is used to realize the spectrum migration of the baseband signal, and digital signal transmission simplifies system design and improves signal stability. The chip is fabricated in 65-nm technology. The experimental results show that the proposed transceiver achieved the highest data rates of 60 Mbps and the measured RX sensitivity is -64dBm. And the chip is also used to set up a multi-sensor nodes communication system to realize the data interaction between one hub and eight slave sensors utilizing the human body as the communication medium.

Ultra-Low Power IoT Solution based on WSSN for Monitoring Infrastructures

In recent years, one of the emerging technologies that have had big impact on the field of research is Wireless Smart Sensors Networks (WSSN) given its diversity of features and applications. The accelerating growth in IoT for data communication, for sensing and monitoring applications (ranging from biomedical to environmental targets) has originated a high demand not only for low-power autonomous devices but also for ultra- low cost combining single chip radio with baseband signal and digital data processing [1]. Target applications, such as Smart Grids, Cyber-Physical Systems, Body Area Networks, Internet of Things (IoT) and high-density environmental sensing networks, will be massively available if it is removed the requirement of explicit human action for energy recharge. A third concern for the deployment of large numbers wireless sensor networks is the cost of each individual remote device.