Signal Transceiver Research Articles

Low-complexity 24-h 29-km inter-island real-time FSO communication under strong turbulences.

Free space optical communication (FSOC) technology can be used for data transmission between ocean islands as backup wireless communication networks to cope with traffic surges and emergencies. In this paper, we experimentally demonstrate the results of a 24-h real-time single-wavelength 2.5-Gbps FSOC between two islands 29 km apart at a low altitude with low complexity. On-off keying signals generated by field-programmable gate array (FPGA) board and commercial low-cost SFP + optical modules are employed as transceiver signals. At the receiving end, a 250-mm large-aperture Cassegrain telescope and 105-µm multi-mode fibers (MMFs) are utilized to reduce the scintillation index from 1.5 to 0.48 and from 0.55 to 0.25 under strong and weak fluctuations, respectively. The averaged receiving optical power, scintillation index, and average bit rate error (BER) are experimentally observed over a 24-hour period with an averaged transmitting power of 36 dBm. The experimental results show that the proportions reach 93.73% and 99.9% for BER below 1 × 10-6 and 1 × 10-3, respectively.

Enhanced performance of secondary surveillance radar system in dense UAV environments using CDMA techniques

AbstractIn future battlefield scenarios, the high density of platforms often leads to multiple responses from existing secondary surveillance radar (SSR) systems, causing collision interference of response signals in the time domain. The frame slotted ALOHA (FSA) algorithm originally used by the system cannot ensure a high identification probability and has a long identification time. In response to these problems, this paper explores the problems of current SSR systems under the urgent need for precise multi‐target identification in dense environments. It investigates how to integrate code division multiple access (CDMA) technology with the ALOHA algorithm to enhance the system's target identification probability. The authors propose an improved workflow and signal transceiver principles for the SSR system and validate the excellent performance of the SSR system in multi‐target identification within dense environments through simulation experiments based on the proposed composite anti‐collision algorithm.

Research on Energy Efficiency Optimization of Visible Light Communication Based on Non-Orthogonal Multiple Access

As a contender in the competitive landscape of next-generation wireless communication technologies, visible light communication (VLC) stands out due to its potential for enhancing transmission rates and spectrum resource utilization. VLC offers various advantages, including license-free operation, high confidentiality, and cost-effectiveness. However, practical implementation faces challenges stemming from the limited modulation bandwidth of light-emitting diodes (LEDs), constraining system capacity and VLC communication rates. To address this limitation, non-orthogonal multiple access (NOMA) emerges as a novel multiple access strategy, particularly suitable for enhancing the capacity and communication rates of downlink VLC systems through power multiplexing. This paper delves into the energy-efficient design of joint LED association and power allocation (LA–PA) for downlink NOMA-based VLC systems. Through an analysis of channel capacity, we transform the non-convex energy-efficient optimization model, accounting for signal non-negativity, per-LED optical power constraints, and user rate constraints, into a convex form. Subsequently, we propose an iterative power allocation algorithm to attain solutions for the optimization problem with pre-established LED associations. Furthermore, we derive a feasibility condition for an LED association, considering signal non-negativity, per-LED optical power constraints, power constraints for successive interference cancellation (SIC), and channel gain between transceiver signals. This condition identifies feasible LEDs capable of maximizing energy efficiency (EE) when combined with the aforementioned power allocation algorithm. Finally, we illustrate the superiority of the joint LA–PA scheme in terms of the EE, transmission reliability, and transmission capacity performance gain over NOMA in the context of VLC.

High resolution imaging of acoustic orbital angular momentum wave based on orthogonal matching tracking

The orbital angular momentum (OAM) wave has shown great potential for improving radar imaging and underwater communication performance due to its helical wavefront phase and infinite orthogonal modes. However, there are currently no known applications of this technology in underwater imaging. In this paper, we employed acoustic OAM wave for underwater imaging and established transceiver signal models using the uniform circular array. We concurrently achieved two-dimensional imaging of azimuth and elevation angles, which differs from radar imaging. We proposed a matching process for the echo signal in the modal domain, the OAM wave beam image's sidelobe decreased by 7.9 dB in the elevation direction and 6.1 dB in the azimuth direction compared to the plane wave, with the mainlobe decreased by 0.2° in the elevation direction and 0.4° in the azimuth direction. Furthermore, this paper introduced OAM wave high-resolution image reconstruction based on the orthogonal matching pursuit (OMP) algorithm. Finally, we implemented broadband acoustic OAM wave for underwater imaging and introduced an image reconstruction method based on the modal domain OMP algorithm. Simulation results demonstrate that the use of OAM wave in underwater imaging is feasible, and the proposed scheme can achieve high-resolution imaging.

A 25‐Gb/s/pin ground‐referenced signaling transceiver with a DC‐coupled equalizer for on‐package communication

SummaryThis paper proposes a wireline serial link transceiver for on‐package die‐to‐die links based on 12‐nm fin field‐effect transistor (FinFET) technology. The link is crucial for improving the computational performance of larger systems built from chiplets. To achieve high pin/energy efficiency and prevent traditional single‐ended signaling disadvantages, the transceiver adopts single‐ended ground‐reference signaling (GRS) to transfer information. To precompensate for the frequency‐dependent loss, retain the advantages of GRS, and avoid the disadvantages of traditional AC‐coupled equalizer, the transmitter in the transceiver adopts a DC‐coupled switched‐capacitor charge pump equalizer that can transmit GRS and its equilibrium value can be adjusted according to the channel attenuation. This paper proposes a method for timing de‐skew using digital control delay lines to eliminate the timing skew between data and the clock. In addition, this paper presents a duty cycle corrector to avoid duty cycle distortion, with an adjustment range of 44.5% to 52% and a power dissipation of only 30 W. The transceiver has an area of 1.016 0.676 mm2, including one clock lane link and four data lane links. At a nominal 0.8‐V power supply voltage, the aggregate eye‐opening of the measured 25 Gb/s data on an organic substrate channel with an attenuation of −2.2 dB over 6 mm is 0.675 UI, with a bit error rate (BER) of less than 10−12 and an energy efficiency of 1.01 pJ/bit.

Intelligent Reflecting Surface for MIMO VLC: Joint Design of Surface Configuration and Transceiver Signal Processing

With the capability of reconfiguring the wireless electromagnetic environment, intelligent reflecting surface (IRS) becomes a new paradigm for designing future wireless communication systems. In this paper, we consider optical IRS for improving the performance of visible light communication (VLC) under a multiple-input and multiple-output (MIMO) setting, where the mean square error (MSE) of the IRS-aided MIMO VLC is minimized by jointly designing the IRS and transceiver signal processing. To this end, the MIMO channel gains of the IRS-aided VLC are first derived under the point source assumption, based on which the MSE minimization problem is formulated subject to the emission power constraints and the IRS configuration constraints. Next, we propose an alternating optimization algorithm, which decomposes the original problem into three subproblems, to iteratively optimize the IRS configuration, the precoding and detection matrices for minimizing the MSE. Moreover, theoretical analysis on the performance of the proposed algorithm in high and low signal-to-noise ratio (SNR) regimes is investigated, revealing that the joint optimization process can be simplified in such special cases, and the algorithm’s convergence property and computational complexity are also discussed. Finally, numerical results show that IRS-aided schemes significantly reduce the MSE as compared to their counterparts without IRS, and the proposed algorithm outperforms other baseline schemes.

The Development of the Real Time Target Simulator for the RF Signal of Electronic Warfare using VST and FPGA

In this paper, the target simulator for RF signals was developed by using VST(Vector Signal Transceiver) and set by real-time signal processing SW programs. A function to process RF signals using FPGA(Field Programmable Gate Array) board was designed. The system functions capable of data processing, raw signals monitoring, target signals(simulated range, velocity) generating and RF environments data analyzing were implemented. And the characteristics of modulated signal were analyzed in RF environment. All function of programs for processing RF signal have options to store signal data and to manage the data. The validity of the signal simulation was confirmed through verification of simulated signal results.

Wireless signal modulation technology

In this paper, based on wireless signal modulation technology, this paper introduces the more mainstream new modulation techniques, including OFDM, GFDM, and UFMC, in recent years. The second part of the article will introduce the wireless communication modulation techniques, the signal transceiver mechanism, and the principle of each part to realize the three systems. In the third part of the paper, the performance of each system in a noisy environment will be simulated and analyzed using the Matlab platform, including the BER comparison and analysis of different systems under different signal-to-noise ratios. In addition, the development of each modulation technology in recent years and the advantages of each technology will be introduced in this part, based on which the corresponding application scenarios and future development trends are also presented. In the future development of communication technology, each technology will also have its development prospect and expectation.

A Wirelessly-Powered Body-Coupled Data Transmission with Multi-Stage and Multi-Source Rectifier

This paper demonstrates body-coupled (BC) data transmission and multi-source power delivery systems for neural interface applications. The implanted data transmitter and power receiver utilize an electrode interface rather than an antenna or coil interface for battery-free wireless transmission, enabling the external data receiver and power transmitter with patch electrodes to be placed away from the implant without requiring precise alignment, which is a critical issue in the conventional communication modalities of inductive coupling. Significantly, the implanted power receiver produces the supply voltage using ambient body-coupled 50/60 Hz signals from the Mains, on top of the 40.68 MHz wireless power source from the external power transmitter, to increase the recovered power level and the voltage conversion efficiency (VCE). The body-coupled wireless systems for implanted and external devices are implemented with integrated circuits (ICs) fabricated in a 180 nm CMOS process. When 650 mVpp AC voltage is applied to the implanted device, the power receiver recovers up to 780 μW with ambient (60 Hz signals) BC energy harvesting, achieving 93% VCE, while 600 μW is recovered without ambient (60 Hz signals) signal. The recovered power supplies the regulated voltage to the direct-digital signaling transceiver, which consumes 460 μW with an uplink data rate of 10 Mbps and a downlink data rate of 200 kbps, corresponding to an energy efficiency of 46 pJ/b.

Transmitter Gelombang Frekuensi Radio (RF) FM Berbasis Raspberry Pi

In recent years, technology in the telecommunications sector has developed rapidly, especially with the global situation encouraging the use of long-distance communications. One of these developments is the use of the Raspberry Pi, abbreviated as Raspi, as a substitute for conventional computers for receiving and transmitting FM radio signals. Raspberry Pi is a mini and portable computer that can be used as an alternative to conventional computers in general, such as the use of teleconference media, offices, Big Data, and as a video player with high resolution. The problem in using a computer as an FM radio signal transceiver system is its complex and expensive infrastructure. When compared to the Raspberry Pi 3 with a price range of IDR 500,000 - IDR 1,000,000, a transceiver system using conventional computers requires a computer in general at a price far exceeding the said price. Using Raspi makes it easy to transmit FM radio signals by simply coding through the Raspi terminal. In this study, the authors propose a transmitter system using a Raspberry Pi 3B+ which is connected to a dipole antenna at a working frequency of 100 – 101 MHz. Raspi is operated using the SSH protocol for remote desktops. The operating system used is Raspberry Pi OS with the use of a MAC computer (MAC OS) as a remote desktop. The results show that the Raspberry Pi device can be used to transmit FM radio signals at a frequency of 100 - 101 MHz. The dipole antenna tested using VNA (Vector Network Analyzer) with a length of 71 cm and a linear form can transmit a signal with a VSWR of 1.08 - 1.95:1 at a working frequency of 94.9 - 103.06 MHz and a return loss of -28.1 dBm at a frequency of 98.98 MHz.

Injection signal coding based topology identification method and system for low voltage substation

In view of the low efficiency and low reliability of the traditional topology identification method of distribution station area, this paper proposes a low-voltage station area topology identification method based on injection signal coding. The signal transceiver terminal sends the topology identification signal, which is composed of preamble, equipment ID number and characteristic code composed of multiple groups of characteristic waves. The rest of the signal transceiver terminals judge whether it is on the same branch and the hierarchical relationship through the characteristic code, The intelligent fusion terminal finally realizes the topological relationship of the whole station area by statistics and analysis of the connection relationship and hierarchical relationship between all the branch master tables. A low-voltage distribution station area is selected to verify the topology identification method proposed in this paper. The test results show that the results obtained by this method are consistent with the real household transformer relationship, and the identification accuracy is high, which has certain engineering application value.

Time Reversal for 6G Spatiotemporal Focusing: Recent Experiments, Opportunities, and Challenges

Late visions and trends for the future 6G of wireless communications advocate, among other technologies, the deployment of network nodes with extreme numbers of antennas and up to terahertz frequencies as a means to enable various immersive applications. However, these technologies impose several challenges in the design of radio-frequency (RF) front ends and beamforming architectures as well as ultrawideband waveforms and computationally efficient transceiver signal processing. In this article, we revisit the time-reversal (TR) technique, which was initially experimented in acoustics, in the context of large-bandwidth 6G wireless communications, capitalizing on its high-resolution spatiotemporal focusing realized with low-complexity transceivers. We first overview the representative state of the art in TR-based wireless communications, identifying the key competencies and requirements of TR for efficient operation. Recent and novel experimental setups and results for the spatiotemporal-focusing capability of TR at the carrier frequencies 2.5, 36, and 273 GHz are then presented, demonstrating in quantitative ways the technique’s effectiveness in these very different frequency bands as well as the roles of the available bandwidth and the number of transmit antennas. We also showcase the TR potential for realizing low-complexity multiuser communications. The opportunities arising from TR-based wireless communications as well as the challenges for finding their place in 6G networks, also in conjunction with other complementary candidate technologies, are highlighted.

The Source Structure Design of the Rotating Magnetic Beacon Based on Phase-Shift Direction Finding System.

Target azimuth information can help further improve the accuracy of magnetic orientation, but the current periodic magnetic field generated by the magnetic beacon is multivalued, so it is not suitable for azimuth measurement. According to the distribution of a rotating magnetic field and the phase angle measuring principle, we put forward a new magnetic source structure design of a multiple rotating permanent magnet array by adjusting the spacing d, the rotating speed ω and the initial rotation angle φ, and then verified the mathematical model using COMSOL simulation software. A triple structure was obtained by comparison (d3=3d1=3d2=43 m, d3=3d1=3d2=43 m, φ1=0, φ2=4π5 rad. φ3=π rad), which can produce a strong characteristic magnetic signal similar to a heart-shaped field pattern. Finally, a signal transceiver system was set up for the experiment. The experimental result shows that the waveform of the magnetic signal generated by the real beacon meets the requirement of having a unique maximum value and good directivity within a period, which proves the practical application effect of the structure.

Electroacoustic performance online measurement under extreme pressure using an 11,000-m transceiver

At extreme deep-sea pressure, the assessment of the electroacoustic conversion performance of transducers is a major problem, particularly in the acoustic exploration of seabed sediment in 11,000-m abysses. To address this problem, an online measurement method was proposed for the electroacoustic performance under extreme pressure. The method utilized the 11,000-m transceiver with the high-frequency and narrow-beam characteristics. In the full-depth pressure profile, the transceiver signal was measured online by an extreme pressure simulation device. At different extreme pressure sites, characteristics of the transceiver signal were analyzed using the transceiver signal at atmospheric pressure as the reference. The characteristics included amplitude response characteristics, frequency response characteristics and time-frequency characteristics. The 11,000-m transceiver has verified the stability and reliability of its electro-acoustic conversion performance. It was also analysed the effect of the transducer on the calculation of seabed sediment parameters in a pressure environment.

Wireless Resource Scheduling for High Mobility Scenarios: A Combined Traffic and Channel Quality Prediction Approach

The rapid growth of mobile data traffic in a high-speed scenario imposes great challenges on wireless system design and optimization, where the inherent Doppler shift, frequent cell switching, and large penetration loss will significantly degrade the quality of transceiver signals. Wireless resource scheduling dynamically allocates wireless resources according to the user channel conditions and quality of service requirement, which is an enabling approach to maximize the resource utilization. In this paper, we develop a new wireless resource scheduling method in high mobility scenario to uplift the system performance. We first propose a feature extraction algorithm to extract the spatial traffic characteristics. On this basis, several time-series prediction algorithms are leveraged to predict the traffic volume. Then, we introduce cell switching indicator (CSI) into channel quality prediction to improve the signal-to-noise ratio (SNR) prediction performance. Based on the predicted results of service traffic and user channel quality variations, a resource scheduling strategy is proposed, which compromises the total system throughput and user satisfaction. Simulation results validate the effectiveness of the proposed scheduling algorithm.

In-Place Evaluation of Powering and Signaling Within Fan-Out Multiple IC Chip Packaging

This article confirms the advantage of fan-out (FO) packaging in the electrical performance of power delivery among integrated circuit (IC) chips with the best use of land side capacitors (LSCs). On-chip in-place waveform measurements quantitatively evaluate the integrity of powering and signaling within FO wafer level packaging (FOWLP) multiple chip module (MCM) demonstrators, where a pair of IC chips are assembled with LSCs with different sizes and structures. The IC chip incorporates an array of 12 digital cores and on-chip waveform monitor (OCM) circuits. Each digital core consists of a low-voltage differential signaling (LVDS) transceiver channel that is backed by a static random access memory (SRAM)-based built-in self test (BIST) module and supplied by an on-chip voltage regulator module (VRM). The LSCs are placed on the bottom side of an FO interposer and inserted between the output of VRM and the ground plane almost ideally with the shortest length of physical traces. A Si membrane capacitor of 10 nF sustains the lowest power line impedance over the frequency range of 2.0 GHz more constantly than a multilayer ceramic counterpart, and attenuates the high-order harmonic frequency components to the clocking frequency at 750 MHz. The leverage of LSCs in powering also improves signaling and helps achieve the wider eye openings in LVDS channels. The implications are elaborated for the capacitor selections with respect to the physical types of capacitors, the size of capacitances, and the level of shares in power delivery among digital cores, all toward the higher level of integrity in powering and signaling in FOWLP MCMs.

End-to-End Learning of a Constellation Shape Robust to Channel Condition Uncertainties

Vendor interoperability is one of the desired future characteristics of optical networks. This means that the transmission system needs to support a variety of hardware with different components, leading to system uncertainties throughout the network. For example, uncertainties in signal-to-noise ratio and laser linewidth can negatively affect the quality of transmission within an optical network due to e.g. mis-parametrization of the transceiver signal processing algorithms. In this paper, we propose to geometrically optimize a constellation shape that is robust to uncertainties in the channel conditions by utilizing end-to-end learning. In the optimization step, the channel model includes additive noise and residual phase noise. In the testing step, the channel model consists of laser phase noise, additive noise and blind phase search as the carrier phase recovery algorithm. Two noise models are considered for the additive noise: white Gaussian noise and nonlinear interference noise model for fiber nonlinearities. The latter models the behavior of an optical fiber channel more accurately because it considers the nonlinear effects of the optical fiber. For this model, the uncertainty in the signal-to-noise ratio can be divided between amplifier noise figures and launch power variations. For both noise models, our results indicate that the learned constellations are more robust to the uncertainties in channel conditions compared to a standard constellation scheme such as quadrature amplitude modulation and standard geometric constellation shaping techniques.

Motion Model of Floating Weather Sensing Node for Typhoon Detection

To improve the accuracy of typhoon prediction, it is necessary to detect the internal structure of a typhoon. The motion model of a floating weather sensing node becomes the key to affect the channel frequency expansion performance and communication quality. This study proposes a floating weather sensing node motion modeling method based on the chaotic mapping. After the chaotic attractor is obtained by simulation, the position trajectory of the floating weather sensing node is obtained by space and coordinate conversion, and the three-dimensional velocity of each point on the position trajectory is obtained by multidimensional linear interpolation. On this basis, the established motion model is used to study the Doppler frequency shift, which is based on the software and physical platform. The software simulates the relative motion of the transceiver and calculates the Doppler frequency shift. The physical platform can add the Doppler frequency shift to the actual transmitted signal. The results show that this method can effectively reflect the influence of the floating weather sensing node motion on signal transmission. It is helpful to research the characteristics of the communication link and the design of a signal transceiver for typhoon detection to further improve the communication quality and to obtain more accurate interior structure characteristic data of a typhoon.

Tunable polarization comb based on the electromagnetically induced transparency with hybrid metal-graphene metamaterial

Noted a linear-to-circular polarization comb based on electromagnetically induced transparency (EIT) with hybrid metal-graphene metamaterial in terahertz (THz) spectroscopy. Due to the near field coupling between the bright mode of metal cut-wire (MCW) and multiple dark modes, the multi-peak EIT effect is exhibited under the x-polarized incidence supported by the three-level theory. With another orthogonal MCW etched on the back of the SiO2, the asymmetry responses in both polarized incidences (x- and y-polarized waves) further triggers the linear-to-circular polarization conversion (LTCPC). The values of four corresponding circular-polarized frequencies combined with transmission coefficients respectively are 0.90 THz with 0.45, 1.02 THz with 0.64, 1.15 THz with 0.60, 1.32 THz with 0.53, confirmed via relevant axial ratios and the electric field distributions. On the other hand, the drastic phase changes in transparent windows raise high group delays, among which the maximum value approaches 325 ps. Additionally, DC-voltage-driven graphene strips are doped at both ends of the back MCW to enhance the reconfigurability, superior tunable transmission behaviors illuminated by y-polarization with obvious changes at 0.90 THz and 1.02 THz can be achieved with the dynamic Fermi level fluctuating between 0.01 eV and 0.8 eV. Such an implementation creates a novel path to polarization modulators, signal transceivers, and information transmission devices.

Achievable Rate Analysis and Phase Shift Optimization on Intelligent Reflecting Surface With Hardware Impairments

Intelligent reflecting surface (IRS) is envisioned as a promising hardware solution to hardware cost and energy consumption in the fifth-generation (5G) mobile communication network. It exhibits great advantages in enhancing data transmission, but may suffer from performance degradation caused by inherent hardware impairment (HWI). For analysing the achievable rate (ACR) and optimizing the phase shifts in the IRS-aided wireless communication system with HWI, we consider that the HWI appears at both the IRS and the signal transceivers. On this foundation, first, we derive the closed-form expression of the average ACR and the IRS utility. Then, we formulate optimization problems to optimize the IRS phase shifts by maximizing the signal-to-noise ratio (SNR) at the receiver side, and obtain the solution by transforming non-convex problems into semidefinite programming (SDP) problems. Subsequently, we compare the IRS with the conventional decode-and-forward (DF) relay in terms of the ACR and the utility. Finally, we carry out simulations to verify the theoretical analysis, and evaluate the impact of the channel estimation errors and residual phase noises on the optimization performance. Our results reveal that the HWI reduces the ACR and the IRS utility, and begets more serious performance degradation with more reflecting elements. Although the HWI has an impact on the IRS, it still leaves opportunities for the IRS to surpass the conventional DF relay, when the number of reflecting elements is large enough or the transmitting power is sufficiently high.