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Abstract Frequency shift keying (FSK) signal has been widely used in modern radar systems. To intercept the FSK radar signal with a high interception probability, radar reconnaissance receiver should have an ultra‐wideband receiving ability. The Nyquist folding receiver (NYFR) is a novel non‐cooperative ultra‐wideband receiver and it requires a small amount of equipment. When the FSK radar signal is intercepted by the NYFR, the corresponding output is a hybrid modulation signal. Therefore, it is necessary to investigate the parameter estimation of FSK radar signal intercepted by the NYFR. Herein, based on the NYFR using sinusoidal frequency modulation local oscillator (LO), the drawbacks of several existing parameter estimation methods are first analysed. To overcome these drawbacks, the NYFR architecture is improved by changing the LO modulation type to periodic linear frequency modulation. Then, based on the improved NYFR, a novel parameter estimation approach is proposed according to the LO modulation characteristics and the template matching rule. The proposed method is suitable for different kinds of common FSK radar signal code schemes and its computational load is low. At last, several simulation results show the merits of the proposed method.

Demodulating the modulated signals used in digital communication on the receiver side is necessary in terms of communication. The currently used systems are systems with a variety of hardware. These systems are used separately for each type of communication signal. A single algorithm facilitates the classification and subsequent demodulation of signals without needing hardware instead of extra hardware cost and complex systems. This study, which aims to make modulation classification by using images of signals, provides this convenience. In this study, a classification and demodulation process is done by using images of digital modulation signals. Convolutional neural network (CNN), a deep learning algorithm, has been used for classification and recognition. Images of the signals of quadrate amplitude shift keying (QASK), quadrate frequency shift keying (QFSK), and quadrate phase shift keying (QPSK) digital modulation types at noise levels of 0 dB, 5 dB, 10 dB, and 15 dB were used. Thanks to this algorithm, which works without hardware, the success achieved is around 98%. Python programming language and libraries have been used in training and testing the algorithm. Demodulation processes of these signals have been performed for demodulation using the nonlinear autoregressive network with exogenous inputs (NARX) algorithm, an artificial neural network. As a result of using MATLAB, the NARX algorithm achieved approximately 94% success in obtaining the information signal. Thanks to the work done, it will be possible to classify and demodulate other communication signals without extra hardware. [ABSTRACT FROM AUTHOR]

Multi-band communication technology allocates the same data to different frequency bands, improving both performance and propagation efficiency. However, since the performance loss in a particular band affects the entire band, the multi-band structure may have worse performance than the single-band one. To avoid performance degradation, this paper proposed estimated coded bit error rates (EC-BER) algorithm. EC-BER algorithm is a method of analyzing the reliability of the received data based on the performance difference between demodulated and decoded data. It analyzes the performance of each band and allocates lower weighting values to inferior bands. Furthermore, an iterative turbo-coded equalization algorithm, which iteratively exchanges probabilistic information between the equalizer and turbo decoder, is applied. By employing a direct sequence spread spectrum (DSSS) with frequency shift keying (FSK) and multi-band techniques for reliable underwater communications, a lake trial was conducted. Experimental results show that the performance is improved as the number of spreading factors and turbo iterations increase. Especially the addition of the EC-BER algorithm dramatically improved the reliability of the system, resulting in minimal to zero errors. [ABSTRACT FROM AUTHOR]

This research article proposes a floating memristor emulator configuration based on n-type MOSFETs only. The proposed memristor comprises three nMOS and an extra nMOS for an external grounded capacitor. Compared to the existing literature, the proposed floating MOS memristor enables a simple design without any sophisticated design complexity. The actual fingerprint of the memristor as a pinched hysteresis loop with different frequency domains and composite characteristics as incremental and decremental are well examined using computer simulation with 90-nm CMOS technology parameters for MOSFETs. The power consumed by the proposed circuit is $2.6~\mu \text{W}$. In addition, an experimental test using off-the-shelf components is investigated to verify the theoretical and simulated results. Moreover, the proposed nMOS-memristor emulator application is suitable for the modulation and demodulation of binary frequency-shift keying (BFSK) and Boolean logic gates. [ABSTRACT FROM AUTHOR]

Memristance gets varied with frequency and duration of write voltage, therefore, multi-bit data was programmed into a memristor through frequency and time based modulation. Three novel memristive programming techniques such as multiple time single frequency keying (MTSFK), single time multiple frequency keying (STMFK) and multiple time multiple frequency keying (MTMFK) were proposed, which enhance the degree of freedom in memristive circuit design. Further, a memristor based frequency shift keying (FSK) demodulator was implemented, which exhibited lower circuit complexity and reduced on-chip area. The effect of the most significant random telegraph noise was observed during the recording of high resistance state measurements and its effect was mitigated through utilizing a simple current mirror approach. The proposed approaches open up a new path for developing memristor based futuristic circuits in the area of electronics and communication, which would offer lower power consumption, on-chip area and latency. [ABSTRACT FROM AUTHOR]

Effective and timely prediction of bit error rate (BER) disturbances is an important means to improve the safety of balise uplink transmission. However, the joint influence of multiple non-stationary factors makes it difficult to predict the abrupt changes of disturbances. To solve this problem, an adaptive attention-based bidirectional stateful encoder-decoder model is proposed for BER disturbances prediction. By persistently transferring the forward and backward states in a batch-to-batch mapping manner, the bidirectional stateful encoder can enhance the capture ability for disturbances. Additionally, an adaptive stateful decoder is used to dynamically synthesize the temporal correlation and contextual summarization to reduce the error accumulation in long-term forecasting. Through effective disturbance discrimination and accumulative error elimination, the proposed model can improve the overall prediction accuracy for BER disturbances. Experiment results on real-world high-speed railway datasets show that the proposed model can achieve superior performance than the state-of-the-art methods. [ABSTRACT FROM AUTHOR]

We consider a finite-state Discrete-Time Markov Chain (DTMC) source that can be sampled for detecting the events when the DTMC transits to a new state. Our goal is to study the trade-off between sampling frequency and staleness in detecting the events. We argue that, for the problem at hand, using Age of Information (AoI) for quantifying the staleness of a sample is conservative and therefore, study another freshness metric age penalty, which is defined as the time elapsed since the first transition out of the most recently observed state. We study two optimization problems: minimize average age penalty subject to an average sampling frequency constraint, and minimize average sampling frequency subject to an average age penalty constraint; both are Constrained Markov Decision Problems. We solve them using the Lagrangian MDP approach, where we also provide structural results that reduce the search space. Our numerical results demonstrate that the computed Markov policies not only outperform optimal periodic sampling policies, but also achieve sampling frequencies close to or lower than that of an optimal clairvoyant (non-causal) sampling policy, if a small age penalty is allowed. [ABSTRACT FROM AUTHOR]

Orthogonal frequency division multiplexing multiple frequency shift keying (OFDM-MFSK) is a promising modulation mode in low cost underwater acoustic (UWA) communication for its ability of resisting multipath fading Doppler effect without introducing channel estimation and equalization. In this paper, an error control method for OFDM-MFSK underwater communication system is introduced which allows the transmitter to send extra redundant codes by phase slit keying modulation. The receiver calculates the error pattern and check code to correct information sequences correspondingly. Compared with other forward error correction codes, the error control method in this paper has lower computational complexly. By combining the OFDM- MFSK system, it can also highly reduce the implementation cost of underwater acoustic communication system while ensuring communication reliability and real-time performance, which is applicable for the design of low- rate underwater acoustic communication equipment. [ABSTRACT FROM AUTHOR]

Long-range (LoRa) modulation is an orthogonal modulation scheme that uses linearly-modulated up chirps to represent information bits. Its constant envelope and good bit-error-rate performance make it one of the key players in establishing low-power wide-area networks for the Internet of things applications. However, LoRa modulation has low data rates. In this letter, we propose a new constant-envelope modulation scheme, named slope-shift-keying and interleaved-chirp spreading (SSK-ICS) LoRa modulation, that can deliver higher data rates than the conventional LoRa modulation scheme. Succinctly, the proposed SSK-ICS-LoRa modulation uses up chirps, down chirps, interleaved up chirps and interleaved down chirps to expand the signal set and hence can carry more bits per transmission symbol. For the same spreading factor and bandwidth consumption, the proposed scheme is able to improve the data rate of the conventional LoRa scheme up to 28.6%. We also present the optimal maximum-likelihood detectors for both coherent and non-coherent demodulators for the proposed scheme. Simulation results show that the proposed scheme outperforms LoRa modulation in both data rate and bit-error rate. [ABSTRACT FROM AUTHOR]

This article presents an instruction-set extension to the open-source RISC-V ISA (RV32IM) dedicated to ultra-low power (ULP) software-defined wireless IoT transceivers. The custom instructions are tailored to the needs of 8/16/32-bit integer complex arithmetic typically required by quadrature modulations. The proposed extension occupies only two major opcodes and most instructions are designed to come at a near-zero energy cost. Both an instruction accurate (IA) and a cycle accurate (CA) model of the new architecture are used to evaluate six IoT baseband processing test benches including FSK demodulation and LoRa preamble detection. Simulation results show cycle count improvements from 19 to 68 percent. Post synthesis simulations for a target 22nm FD-SOI technology show less than 1 percent power and 28 percent area overheads, respectively, relative to a baseline RV32IM design. Power simulations show a peak power consumption of 380 µW for Bluetooth LE demodulation and 225 µW for LoRa preamble detection (BW = 500 kHz, SF = 11). [ABSTRACT FROM AUTHOR]

The modulation mode recognition of non-cooperative underwater acoustic (UWA) communication signal faces great challenges due to the influence of the UWA channel and the demand for efficient recognition. This work proposes a recognition method for UWA orthogonal frequency division multiplexing (OFDM), binary frequency shift keying (2FSK), four-frequency shift keying (4FSK), and eight-frequency shift keying (8FSK) by using spectral peak feature extraction combined with random forest (RF). First, a new spectral peak feature extraction method is proposed. In this method, pre-processing, waveform optimization, and feature extraction are used to ensure that the extracted feature maintains high robustness in the UWA channel. Then, we designed an RF classifier that can meet the demand for high-efficiency recognition and good performance. Finally, simulation and experimental results verified the feasibility of the recognition method. [ABSTRACT FROM AUTHOR]

In the same year, Zhang et al. analyzed the loss mechanism of resistor loaded on the SSPP unit, providing a new method to predict the attenuation of lossy active SSPP devices [[26]]. The proposal of active SSPP device can overcome this inflexibility by incorporating active elements, such as diode, transistor, and state-change medium, into the SSPP structures. Keywords: amplitude modulation; frequency modulation; Mach-Zehnder interferometer; reconfigurable device; spoof surface plasmon polaritons EN amplitude modulation frequency modulation Mach-Zehnder interferometer reconfigurable device spoof surface plasmon polaritons 1913 1921 9 05/12/22 20220401 NES 220401 1 Introduction Surface plasmon polaritons (SPPs) are highly localized surface waves that propagate along the interface between two materials whose real parts of permittivity are positive and negative (such as air and metal in the optical frequency), respectively. Gao et al. proposed a multi-functional device composed of two active SSPP waveguides and a substrate integrated waveguide (SIW) [[29]], where the control of the cutoff frequencies enables the device to switch between a power divider and a band-pass filter. [Extracted from the article]

A design scheme for embedding a chipless radio frequency identification (RFID) tag in a quick response (QR) code is proposed and demonstrated. By searching for QR modules that can be metalized to form a loop resonator in the edge area and to load the loop in the central area, the chipless RFID tag with an optimized loaded-loop resonator can be designed in the QR code. A specific loop genetic operator is proposed for optimization searching. The optimized loaded-loop resonator has a sharp dominant resonant peak at frequency as low as possible and a harmonic resonant peak at frequency as high as possible, which provides large space for data encoding of chipless RFID. By removing or demetalizing the metalized loading modules, the resonant frequency can be tuned conveniently for frequency shift keying (FSK) coding. For demonstration, the chipless RFID tag embedded in the QR code is designed and tested. It is shown that the RFID tag allows at least nine distinct resonant frequencies for simple FSK coding, which indicates a coding capacity of 3.17 bits and a normalization coding density of approximately 501.78 bits/ $\lambda _{\mathrm {g}}^{2}$ /GHz for the chipless RFID tag embedded in the QR code. [ABSTRACT FROM AUTHOR]

Automatic modulation classification (AMC) is a process of automatic detection of modulation format imposed on the received signal with no prior information (carrier, signal power, phase offset) of the signal, also known as blind classification. In this paper, we proposed a new AMC algorithm, by combining the synergy of the meta-heuristic technique with Gabor feature extraction mainly used in texture analysis. Gabor filters are used to extract the features that are further optimized using the cuckoo search algorithm to increase the efficiency of the classification procedure. The classification approach is applied on digitally modulated signals having phase-shift keying, frequency-shift keying, and quadrature amplitude modulation schemes of order 2–64 over the nonfading channel (AWGN) and fading channel (Rayleigh). Simulations and performance comparison with the existing literature validate that the proposed solution has better classification accuracy with lower sample size and lower signal-to-noise ratio. [ABSTRACT FROM AUTHOR]

Simultaneous wireless power and data transfer (SWPDT) is widely investigated because of the increasing requirement for real-time communication between the primary and secondary sides in wireless power transfer systems. This article classifies SWPDT systems into four categories according to the type and number of data channels and data carrier generation method. They are power carrier-based SWPDT system, high-frequency data carrier-based SWPDT system, multiple inductive channels SWPDT system, and inductive–capacitive hybrid channels SWPDT system, respectively. Four key issues, including cross-talk minimization, improvement of signal-to-noise ratio, modulation method for high data rate and low bit error rate, and special design to achieve full-duplex communication and improve misalignment tolerance, are discussed. The advantages, disadvantages, and applications of the four types of SWPDT systems are summarized. Finally, conclusions and outlook of the SWPDT system are given. [ABSTRACT FROM AUTHOR]

In this paper, the performance of the selective combining according to the channel selection decision method of frequency diversity is evaluated in the underwater frequency selective channel. The underwater acoustic channel in the shallow sea has a complex multipath characteristic by combining various environmental factors such as boundary surface reflection and sound wave refraction according to the water temperature layer. In particular, frequency selectivity due to multipath causes energy fluctuation in a communication channel, which reduces SNR (Signal to Noise Ratio) and deteriorates communication performance. In this paper, we applied the frequency diversity technique using multiple channels to secure the communication performance according to the frequency selectivity by multipath. For each channel, 4-FSK (Frequency Shift Keying) and selective combining were applied, the performance was evaluated by applying the maximum value, average value, and majority decision of the signal in order to decide the demodulation channel selection of the selective combining. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a multitone simultaneous wireless information and power transfer (SWIPT) based modulation scheme for battery-less Internet of Things (IoT) nodes that works in the ultra high frequency (UHF) region. The conventional SWIPT system is assumed to have power-consuming communication modules. Having such modules on to the IoT nodes whose power is harvested from radio frequency (RF) power sources is too unrealistic. In addition, waveform design from the aspect of power harvesting through SWIPT still has room for consideration. Recent studies have explored multitone based SWIPT to increase the power conversion efficiency (PCE). In these schemes, information is modulated by changing each tone's nature or varying the number of tones. Among these methods, we focused on modulation schemes known as frequency-shift multitone based SWIPT, which shifts frequencies among the tones for information encoding. Unlike previously proposed methods where demodulation requires some power-consuming fast Fourier transfers (FFTs), especially under small communication bandwidths, we applied a signal detection method by measuring output peak to average power ratios (PAPRs) for frequency-shift multitone based SWIPT to reduce power consumption. Based on our analysis, different tone configurations in the frequency domain would yield varieties of nonlinear outputs during the rectification process. In addition, these specific nonlinear output patterns depend on the tone configurations. With this feature, it is possible to demodulate in the time domain at the receiver side using PAPR based measurements, which could eliminate FFT operation. This paper describes how measuring PAPRs enables the detection of signals in theory and validates this through simulations and experiments. We also estimate the communication rates. Based on our results, we achieved 0.46 bits/s/Hz when the number of tones was 6 and estimated that there were $(N-1)(N-2)/2 + 1$ different PAPRs from a given multitone waveform whose number of tones was $N$ .

A photonic approach to generate multiform microwave frequency shift keying (FSK) signal is proposed. In the scheme, a dual-polarization quadrature phase shift-keying (DP-QPSK) modulator along with a polarization controller (PC) is employed to generate two orthogonally polarized signals containing specific optical sidebands, and a following tunable filtering switch (TFS) serve as optical sidebands selector. From a theoretical analysis, when the modulators in the scheme are properly biased, we can obtain microwave FSK signal with frequency multiplication factors of 2/4 or microwave FSK signal with flexible tunable subcarrier frequencies. Simulations are conducted to verify the proposed scheme. 10/20GHz and 8/12GHz microwave FSK signals are successfully generated, and the frequency tunability is also demonstrated. In addition, the impact of the non-ideal parameters is analyzed, and the results show that the scheme has good immunity to the small parameters deviation (within 3°). The distinct advantage of our scheme is that we realize multiform microwave FSK signal generation based on a single system, which may find applications in high-frequency multifunction wireless communication system or radar system.

In optical transmission technique using optical polarization, the change of state of polarization (SOP) and the rotation of SOP (RSOP) during optical transmission has a significant impact on the transmission performance. We propose polarized intensity rotational frequency shift keying (PIR-FSK) as a novel modulation technique in change of SOP and RSOP-tolerant optical transmissions. The proposed PIR-FSK signal does not affect the entire intensity of the optical carrier by modulating the sinusoidal signals on each X and Y-polarized optical carrier. Therefore, the proposed PIR-FSK modulation and optical carrier intensity modulation can operate at the same time. Moreover, since the proposed technique does not modulate the signal using the SOP unlike the PolSK, PIR-FSK is not affected by SOP changes that occur during transmission, and the signal does not be degraded even with RSOP. We demonstrated that the signals modulated using the proposed PIR-FSK modulation have higher signal capacity and efficiency compared to the signal modulated using PolSK modulation.

This brief describes an integer-N-type-II sub-sampling phase-locked loop (SS-PLL) incorporating a push–pull sub-sampling phase detector to significantly suppress the spur-induced binary frequency shift keying modulation (BFSK) effect and a low-power fast-locking frequency-locked loop (FLL) to shorten the settling time. Prototyped in 65-nm CMOS, the SS-PLL at 3.3 GHz shows a reference spur of −82.2 dBc, an integrated jitter of 64.9 fsrms (1 kHz to 40 MHz), and an in-band phase noise (PN) of −128.4 dBc/Hz at 1-MHz offset. The corresponding jitter power figure of merit (FOM) is −255 dB. The entire SS-PLL consumes 7.5 mW, with only $90~\mu \text{W}$ associated with the FLL. [ABSTRACT FROM AUTHOR]

Wireless power and datatelemetry based on amplitude-shift keying (ASK) modulation over dual inductive links has been widely adopted in biomedical implants. Due to the mutual inductance between the power and data links, the large power-carrier-interference (PCI) will inevitably cause low signal-to-interference ratio (SIR) of the received signal, thereby increasing the bit-error-rate (BER) of the ASK demodulation. In this paper, an innovative high energy-efficient ASK demodulator robust to PCI has been proposed. Thanks to the proposed sampling-and-subtraction (SAS) architecture, the demodulator is capable of withstanding PCI with an amplitude up to 2.5 times as the data carrier without the need for any high-order filters. The prototype has been implemented with 180 nm standard CMOS process, occupying a core area of 0.51 mm $^{2}$. The experimental results show that with 1 Mbps data rate and 13.56 MHz carrier frequency, the typical BER is less than 1.3×10 $^{-3}$ , while the energy efficiency is 280 pJ/bit, showing 7.5× improvement compared to the prior works. The energy-efficient robustness to PCI demonstrates the potential of the technique to be applied to retina prostheses as well as various kinds of ultra-low-power implantable biomedical devices. [ABSTRACT FROM AUTHOR]

The main objective of this work is to reduce the packet loss due to packet error rate and buffer overflow for under water sensor network. In this work, a system is mapped into various states based on channel condition, buffer space, and available energy level. The set of policies are defined in terms of transmission power level, adaptive modulation scheme, and various transmission rate. We have proposed Optimum Trans–Receiver Scheme (OTRS), in which the problem is formulated as per Markov decision process model and solution is sought in terms of optimum policy identification for an individual state of the system. We have evaluated the performance of OTRS by extensive simulation with existing Adaptive Modulation Power Adaption, Power Adaption with 2 Ary Frequency Shift Keying and Power Adaption with 8 Ary Frequency Shift Keying for various performance matrices like Net Bit Rate and number of packet loss for various state of the system. [ABSTRACT FROM AUTHOR]

A novel stacked magnetic pendulum array (MPA) is proposed as an antenna for efficient transmission in ultralow frequencies (ULF). The MPA structure consists of an array of ${m\times n}$ magnets stacked in $n$ rows (m magnets of the same magnetization per row) and a solenoid that encompasses the array. The magnetic flux generated by the solenoid couples to the magnets through a mechanical motion and creates a strong time variant magnetic field at the resonance frequency of the array. The proposed MPA is developed utilizing bearings with extremely small damping which hold the magnets, enable efficient oscillation, and guarantees a high-quality factor ($Q$ -factor). A comprehensive analysis to study the performance of the MPA and a conventional solenoid will be provided and accordingly, characteristics of an arbitrary ${m\times n}$ array in terms of field strength, resonance frequency, transmission efficiency and inductance are studied. Furthermore, a figure of merit (FOM) is introduced as the ratio of efficiency to the maximum linear dimension of the antenna. The experimental results for a fabricated $5 \times 11$ array show a resonance frequency of 715 Hz and a Q-factor of 94 while the maximum linear dimension of the antenna is just 9 cm. Moreover, measurement results show 24.9 dB improvement in the transmission efficiency of the MPA compared to the efficiency of a single solenoid of the same dimensions. The MPA has the FOM of ${1.26\times 1}{0}^{{4}}$ which is noticeably higher than that of proposed antennas in the literature. To demonstrate broadband transmission with the MPA, a binary frequency shift keying (BFSK) signal is transmitted through the use of direct antenna modulation (DAM) at a rate of 18 bps. [ABSTRACT FROM AUTHOR]

Purpose: The catheter-based ultrasound (CBUS) can reach the target tissue directly and achieve rapid treatment. The frequency shift keying (FSK) signal is proposed to regulate and evaluate tumor ablation by a miniaturized dual-frequency transducer. Methods: A dual-frequency transducer prototype (3( 7 ( 0.4 mm) was designed and fabricated for the CBUS applicator (OD: 3.8 mm) based on the fundamental frequency of 5.21 MHz and the third harmonic frequency of 16.88 MHz. Then, the acoustic fields and temperature field distributions using the FSK signals (with 0, 25, 50, 75, and 100% third harmonic frequency duty ratios) were simulated by finite element analysis. Finally, tissue ablation and temperature monitoring were performed in phantom and ex vivo tissue, respectively. Results: At the same input electrical power (20 W), the output acoustic power of the fundamental frequency of the transducer was 10.03 W (electroacoustic efficiencies: 50.1%), and that of the third harmonic frequency was 6.19 W (30.6%). As the third harmonic frequency duty ratios increased, the shape of thermal lesions varied from strip to droplet in simulated and phantom experimental results. The same trend was observed in ex vivo tests. Conclusion: Dual-frequency transducers excited by the FSK signal can control the morphology of lesions. Significance: The acoustic power deposition of CBUS was optimized to achieve precise ablation. [ABSTRACT FROM AUTHOR]

Backscatter communication is an emerging paradigm for pervasive connectivity of low-power communication devices. Wirelessly powered backscattering wireless sensor networks (WSNs) become particularly important to meet the upcoming era of the Internet of Things (IoT), which requires the massive deployment of self-sustainable and maintenance-free low-cost sensing and communication devices. This article will introduce the state-of-the-art antenna design and radio frequency (RF) system integration for wirelessly powered backscatter communications, covering both the node and the base unit. We capture the latest development in ultralow-power RF front ends and coding schemes for $\mu \text{W}$ -level backscatter modulators, as well as the latest progress in wireless power transfer (WPT) and energy harvesting (EH) techniques. Newly emerged rectenna system, waveform design, and channel optimization are reviewed in light of the opportunities for adaptively optimizing the WPT/EH efficiency for low-power signals with varying conditions. In addition, advanced device packaging and integration technologies in, e.g., additively manufactured RF components and modules for microwave and millimeter-wave ubiquitous sensing and backscattering energy-autonomous RF structures are reported. Inkjet printing for the sustainable and ultralow-cost fabrication of flexible RF devices and sensors will be reviewed to provide a prospective insight into the future packaging of backscatter communications from the chip-level design to complete system integration. Finally, this article will also address the challenges in fully wireless powered backscatter radio networks and discuss the future directions of backscatter communication in terms of “Green IoT” and “Low Carbon” smart home, smart city, smart skin, and machine-to-machine (M2M) applications. [ABSTRACT FROM AUTHOR]

This article describes a novel approach for robust and reliable underwater acoustic communication targeting low data rate applications in very challenging channels. The well-known binary frequency shift keying (BFSK) modulation is extended with multiple pair-wise BFSK subcarriers forming a multicarrier (MC) waveform referred to as MC-BFSK. Time offsets between neighboring subcarriers combined with windowing and guard periods are employed to increase the robustness against Doppler-induced frequency spread/shift and reverberation together with novel methods for synchronization, peak-to-average-power ratio reduction, and soft-value extraction. For the design of the parameters of the waveform, a heuristic approach is utilized. A noncoherent matched filter receiver with spatial diversity is adopted. The MC-BFSK transmission scheme is evaluated by means of computer simulations as well as sea-trial measurements. The obtained results are compared with competing modulation schemes where the proposed MC-BFSK shows better performance in challenging channels. In particular, we are able to decode frames in a sea-trial scenario where the direct path between the transmitter and the receiver is blocked by an island. [ABSTRACT FROM AUTHOR]

Rapid shutdown for rooftop PV cells requires an inside array boundary of 305mm to be de-energized to 30 Volts or less within 30 seconds of initiation of a rapid shutdown event, according to Sunspec specifications. The specification set by Sunspec allows controllers to communicate using a single communication protocol defined by Sunspec, providing interoperability between different components, which utilizes power-line (PLC) communication as a mean of transferring data. This paper proposes a system architecture for a rapid shutdown receiver, that utilizes multi-stage feedback band-pass filtering techniques to actively remove noise from the PLC network and deliver the S-FSK message transmitted to the decision-making block with frequencies to the Mark and Space of frequencies 131.25kHz and 143.75kHz respectively. Furthermore, this paper uses a signal mixing technique to enhance the system's reliability, stability, and provides another layer of security via utilizing the low-frequency as an enabling signal to the decision-making stage (not covered in this paper). [ABSTRACT FROM AUTHOR]

Reconfigurable intelligent surface (RIS) is a key enabler for future paradigm-shifting communication technologies. In a cellular network, an RIS can be used to simultaneously assist the communication of a cellular link and transmit additional data for various Internet of Things (IoT) applications. This coincides with the concept of symbiotic radio (SR). In this paper, we investigate this RIS-assisted SR system. We introduce the new idea of symbiotic modulation: the modulation constellation design allows a receiver to simultaneously detect the data transmitted in the RIS-assisted cellular link and the additional IoT data transmitted by the RIS. We propose three specific modulation schemes all having the feature of receive-antenna index modulation, and hence, called symbiotic spatial modulation (SSM). The first scheme is a coherent SSM scheme with a star-QAM (quadrature amplitude modulation) constellation. Its detection performance is analyzed using either an optimal maximum likelihood detector or a suboptimal successive greedy detector. We then extend the design to two noncoherent SSM schemes and analytically derive their detection performances as well. Simulation results corroborate the analysis and illustrate good detection performance of the proposed SSM schemes for both the cellular and IoT data transmissions in the considered SR system. [ABSTRACT FROM AUTHOR]

This paper presents a frequency-splitting-based wireless power and data transfer IC that simultaneously delivers power and forward data over a single inductive link. For data transmission, frequency-shift keying (FSK) is utilized because the FSK modulation scheme supports continuous wireless power transmission without disruption of the carrier amplitude. Moreover, the link that manifests the frequency-splitting characteristic due to a close distance between coupled coils provides wide bandwidth for data delivery without degrading the quality factors of the coils. It results in large power delivery, high data rate, and high power transfer efficiency. The presented IC fabricated in a 180-nm BCD process simultaneously achieves up-to-115-mW wireless power delivery to the load and 2.5-Mb/s downlink data rate over the single inductive link. The measured overall power efficiency from the DC power supply at the transmitter module to the load at the receiver module reaches 56.7 $\%$ at its maximum, and the bit error rate is lower than 10 $^{-6}$ at 2.5 Mb/s. As a result, the figure of merit (FoM) for data transmission is enhanced by 2 times, and the FoM for power delivery is improved by 38.7 times compared to prior state-of-the-arts using a single inductive link. [ABSTRACT FROM AUTHOR]

The objective of this letter is to improve the reliability of wireless communication from implanted sensors that employ backscatter for the communication technology. This letter describes a frequency modulation approach to improve the Signal to Noise Ratio of the communication link. The technique is based on modulating the toggling frequency of the load switch. It is suitable for standard tags that have only two loads connected to the antenna via a switch. Both coherent and non-coherent demodulations are possible, resulting in feasible options for both external and implantable receivers. Our simulations show 2–3 dB improvement in error performance with low complexity transmitters and receivers. Our results indicate that, to improve communication reliability, frequency modulation may be more suitable than coding in ultra-low power sensors. [ABSTRACT FROM AUTHOR]

Power & signal multiplex transmission (P&SMT) is a technique that uses power electronic circuits for communication signal transmission. In this paper, a three-phase cascaded multilevel inverter-based P&S MT system is proposed. The proposed method can transmit communication signals without using a Controller Area Network bus, thereby reducing the wiring cost of the conventional electric vehicle (EV) communication system. The designed system can achieve motor speed regulation and battery balance discharging for EVs. With the combined pulse width modulation scheme and frequency shift keying method, both power and communication signals are transmitted successfully in a simulation model implemented in Matlab/Simulink. By evaluating the bit error rate of the transmitted signal, the maximum signal rate of the proposed system is determined as 600 bit/s.

Bu çalışmada, evre uyumlu olmayan frekans kaydırmalı anahtarlama ve farksal faz kaydırmalı anahtarlama sayısal modülasyon türlerini kullanan haberleşme sistemlerinin η-µ/Gamma karma sönümlenmeli kanallardaki başarım analizi verilmiştir. Yapılan analiz olasılık yoğunluk fonksiyonu tabanlı olup, matematiksel olarak temel fonksiyonlar içermektedir. Bu sebeple, sunulan analiz matematiksel açıdan oldukça kolay ve anlaşılabilirdir. Yapılan analizler sonucunda kapalı formda ortalama hata ifadesi türetilmiştir. Türetilen hata ifadesi kullanılarak elde edilen nümerik sonuçlar ile simülasyon sonuçları kıyaslamalı olarak verilerek türetilen ifadenin doğruluğu gösterilmiştir.

In wireless power transfer (WPT) system, communication between the primary and the secondary plays an important role in system status monitoring and operation control. Bidirectional information transmission is also essential to detect the working state and send control command in both sides. This article proposes a bidirectional simultaneous wireless information and power transfer method. The secondary has a simple structure and employs only one switch. The proposed WPT system can achieve bidirectional information transmission via a sharing inductive link. The forward information is transferred by using a single full bridge inverter based on selected harmonic elimination PWM (SHEPWM) control methods without other high-frequency signal sources. In the secondary side, uncontrolled rectifier and a parallel MOSFET are adopted to realize constant voltage output and backward information transfer. The backward information modulation is achieved by changing the switching frequency of MOSFET. The forward and backward information demodulation modules are designed and analyzed in details. A 30W experiment platform with forward communication rate 5 kbps and backward communication rate 10 kbps is built to verify this proposed method.

The communication system of a microgrid can transfer the information of electricity price, power consumption and so on between users and the control centre. This capability is of great significance to improve the efficiency and sustainability of power facilities. In this paper, a bidirectional DC–AC converter topology is proposed to achieve the composite transmission of power and signals in microgrids. Since the transmitted signals are modulated by power switches of converters and integrated into the currents, the cost of signal couplers can be saved and the circuit structure can be simplified. In order to verify the feasibility of the proposed method, a simulation model of the proposed converter is implemented in MATLAB/Simulink. With the power supply frequency of 50 Hz, when the converter operates in the inverter mode and rectifier mode, the data transmission rate can reach 120 bit/s and 48 bit/s, respectively.

We studied the dependence of the Brillouin frequency shift (BFS) on the water-absorption ratio in poly(methyl methacrylate)-based polymer optical fibers (POFs) to clarify the effect of the humidity on POF-based Brillouin sensors. The BFS, deduced indirectly using an ultrasonic pulse-echo technique, decreased monotonically as the water absorption ratio increased, mainly because of the decrease in the Young's modulus. For the same water absorption ratio, the BFS change was larger at a higher temperature. The maximal BFS changes (absolute values) at 40, 60, and 80 °C were 158, 285, and 510 MHz, respectively (corresponding to the temperature changes of ~9 °C, ~16 °C, and ~30 °C). Thus, some countermeasure against the humidity is indispensable in implementing strain/temperature sensors based on Brillouin scattering in POFs, especially at a higher temperature. On the other hand, Brillouin-based distributed humidity sensors might be developed by exploiting the BFS dependence on water absorption in POFs. [ABSTRACT FROM AUTHOR]

Bilayer microcantilevers are normally curved because of fabrication-induced stresses. When used in biological/chemical sensing applications, the absorption of target agents onto the functionalized surface of the microcantilever creates a surface stress that shifts its resonance frequency. Despite numerous efforts, the mechanisms of surface stress-induced shift in the resonance frequency of microcantilevers remain elusive. To address this problem, this work presents a detailed analysis of the frequency response of microcantilevers, with different width-to-thickness ratios and curvature levels, using classical lamination theory and the Rayleigh-Ritz method. Based on the results of this analysis, a new relationship between resonance frequency shift and curvature variation due to differential surface stress loading is established. By comparing the strain energies associated with the in-plane and out-of-plane displacements of the microcantilever at different curvature levels, a new implicit model for surface stress-induced resonance frequency shift in microcantilevers is presented. Verified against the results of experiments carried out on gold/polysilicon microcantilevers, the new model is expected to provide a better understanding of surface stress-microcantilever resonator interaction, which is critical to systematic optimization of resonance-based micro sensors. [ABSTRACT FROM AUTHOR]

Due to the severe impact of dynamic plasma sheath on electromagnetic (EM) waves, the communication quality of hypersonic vehicles deteriorates, even resulting in communication blackouts during the reentry process. In this article, the hypersonic vehicle downlink integrated channels that cascade the plasma sheath channel and Rice fading channel, i.e., the downlink telemetry channels, are first established, and then the demodulation method and performance of typical telemetry modulations including the M-ary phase shift keying (MPSK), M-ary amplitude shift keying (MASK), and M-ary frequency shift keying (MFSK) are studied. Considering the high dynamics of the plasma sheath, the pilot signals are used to detect the signal correctly for MPSK, and the non-coherent demodulation is adopted for MASK and MFSK. Especially, an adaptive maximum likelihood (ML) receiver for ASK is proposed based on a reduced reversible jump Markov chain Monte Carlo (RRJ-MCMC) algorithm to estimate the probability density function (pdf) of the received signal. The simulation results show that the communication performance of PSK and ASK is improved with the modulation order $M$ decreasing; the performance of non-coherent FSK is improved with the modulation order $M$ increasing. Meanwhile, the performance follows the order of NC-MFSK (M ≥ 8) > BPSK > NC-4FSK > NC-2FSK > 2ASK. For NC-8FSK, when the electron density peak value ${Ne}_{\mathrm {peak}}$ = {2, 4, 6, 8, 10} $\times 10^{18}\,\,\text{m}^{-3}$ , the signal to noise ratio (SNR) required to reduce the bit error rate (BER) to 10−6 are 17, 18, 19, 21, and 34 dB, respectively. [ABSTRACT FROM AUTHOR]

This article presents a simultaneous wireless power and data transfer (SWPDT) system based on double-sided inductor–capacitor–capacitor compensation topology and frequency-shift keying. A simplified method to analyze the power transfer, data transfer, and interference between them is proposed. To obtain higher data transfer gain and lower bit error rate, the data injection and extraction transformers are optimized. A laboratory prototype was built to verify the correctness of the analysis and the methodology. The proposed SWPDT system is less susceptible to interference between the power and data transfer. This is experimentally proven by high signal-to-noise ratio of 47 dB in the worst case. The power transfer efficiency is 90.5% under nominal conditions, and the data rate is 150 kb/s. The proposed system is robust against coupling variations, with effective data transfer even though the coupling coefficient is decreased by 95.3%. [ABSTRACT FROM AUTHOR]

For generating digital codes based on the frequency of input signal we need frequency shift keying demodulators. Optical demodulators are required for optical communication networks. In this paper we are going to design and propose a new structure for implementing all optical frequency shift keying demodulator. The proposed structure was designed using four resonant rings. Finite difference time domain method was used for simulating the propose structure. The simulation results show that when the frequency of input signal is 193.5 THz, 194 THz, 194.5 THz and 195 THz the proposed structure can generate 00, 01, 10 and 11 code at the output ports respectively. The maximum delay time of the proposed structure is 2 ps. [ABSTRACT FROM AUTHOR]

A wireless frequency shift keying (FSK) transceiver that can simultaneously transmit and receive over the same radio channel using a novel complex baseband technique is introduced. The proposed design combines a traditional FSK modulator with a new frame-based demodulation technique able to recover data without using traditional cancellation techniques. Self Interference (SI) level has no impact on demodulation and can be ignored. The mathematical equations are detailed and validated by simulation. The implementation through software defined radio (SDR) using Ettus B210 USRP and GNU Radio proves that the system works properly and enables the In-Band Full-Duplex (IBFD) for FSK. An example of one single hope real-world IBFD communication is presented. Energy efficiency and System performances have been also evaluated using the bit error rate (BER) curve and discussed. The proposed technique enhances the spectral efficiency by factor 2 and seems very useful for low-rate applications such many internet of things (IoT) devices. [ABSTRACT FROM AUTHOR]

The Arctic Ocean and its various shallow passages are rapidly changing due to global warming. The development of a large-scale wireless network that collects and distributes oceanographic data remotely would be an extremely valuable asset to researchers. This concept, however, is completely dependent upon the ability to acoustically transmit digital information under water over long ranges, which is not currently available. In this work, we investigate the performance of four transceivers that are based on frequency-hopping binary frequency-shift keying and multilevel phase-shift keying (M-PSK) signaling in the 300 $-$ 400-Hz acoustic band. The transceivers use low-rate coding that provides bit rates from 1.8 to 13.3 b/s (bits per second). Their bit error rates are computed based on real data recorded in Barrow Strait (NU). During the 2019 experimental activities, the transmitter was towed by a supporting vessel at an average speed of 4 kn. The receiver, a vertical hydrophone array, was at distance between 14 and 33 km. Additionally, the received signals experienced extended multipath propagation and strong in-band impulsive interferences. For a single-hydrophone receiver, our postprocessing analysis shows reliable bit rates up to 6.7 b/s. When processing uses the array and performs multichannel decision feedback equalization (DFE), the maximum designed rate, i.e., 13.3 b/s, is confirmed. Further analysis reveals that the experimental links could support higher data rates. Our results demonstrate that 2-PSK signaling combined with single-channel DFE and 4-PSK signaling combined with multichannel DFE could reliably achieve 100 and 200 b/s, respectively. [ABSTRACT FROM AUTHOR]

A 900-MHz high-sensitivity split-channel binary frequency-shift keying (SC-BFSK) reconfigurable data/wake-up receiver (RX) for low-power wide-area networks (LPWANs) is presented. In the data mode, the proposed RX demodulates data through the RF/analog front end (RXFE), the analog-to-digital converter (ADC), and the modulator–demodulator (MODEM). The MODEM implemented in the external microcontroller unit (MCU) applies additional digital signal processing to improve about 17-dB sensitivity. In the wake-up mode, the proposed RX saves the power dissipation by turning off all blocks except for the RXFE and wake-up preamble detector (WuPD). The WuPD following the RXFE provides a 17-dB sensitivity improvement in place of the MODEM of the data RX. Adopting the proposed SC-BFSK, in which other channels are inter-allocated between the BFSK tones of one channel, increases the number of channels while taking advantage of wide tone spacing, which improves the bit error rate (BER) in a multipath fading channel. To implement the ultra-low-power (ULP) SC-BFSK RX, the RXFE employs the 2:1 LO sliding-IF architecture and a band-pass filter (BPF)-based frequency-to-energy detection baseband demodulator. Implemented in 55-nm CMOS, the proposed RX, including both data and wake-up RXs, exhibits −123-dBm sensitivity with 0.39-kbps data rate and 81.92-ms wake-up latency, while the RX chip dissipates 0.88 mW. [ABSTRACT FROM AUTHOR]

The noise immunity of receiving signals with pseudorandom tuning of the operating frequency in low-speed radio communication systems under the influence of jamming in a part of the band is considered. The dependences of the error probability of signal reception on the signal-to-noise ratio and on the frequency parameters of the interference for various algorithms for receiving signals of frequency shift keying with intrasymbol pseudorandom tuning of the operating frequency are obtained. The effectiveness of the considered reception methods is estimated. [ABSTRACT FROM AUTHOR]

The reflectarray antenna is typically used in wireless communication systems to extend the communication range. In this work, we adapted a reflectarray antenna to inexpensive radar transceivers, thereby increasing the range of the radar without modifying the electronic circuits. The reflectarray antenna is designed for battery-operated portable devices, therefore the dimension (30 x 20 cm) and weight (~1/4 kg) were minimized as much as possible. The detailed design process of the reflectarray antenna and performance improvements, including the range increase of a human target, are presented. The feeders of the reflectarray radar system tested in this study are off-the-shelf, low-profile 24 GHz traffic monitoring radar transceivers with the gain of the antenna at around 10.71 dBi. The demonstrated reflectarray antenna has a gain of 21.18 dB, resulting in a combined total gain of 31.89 dBi. The performance of the radar system with the designed reflectarray antenna was evaluated using frequency modulated continuous wave (FMCW) and frequency shift keying (FSK) modulations. The range and speed measurements of a human target using both techniques revealed that the reflectarray antenna does not degrade the accuracy of the speed while increasing the range three-fold. Compared with conventional antenna gain boost methods, the reflectarray provides a simple, lightweight, inexpensive and flexible option for increasing the range of the radars. [ABSTRACT FROM AUTHOR]

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We propose a new transmit diversity technique for frequency shift keying (FSK). The main idea behind our proposed scheme is to exploit the orthogonality between FSK carriers in order to render signals transmitted from different antennas orthogonal at the receiver, which results in full diversity. Since the proposed scheme achieves antenna orthogonality within one time unit while the well-known Alamouti space-time block code (STBC) needs two time units, it succeeds to be more robust against time-selectivity of the channels than the STBC without deteriorating peak-to-average power ratio (PAPR) of the signal. Simulation demonstrates that the proposed scheme has an error floor that is ten times lower than the STBC over time-selective channels. [ABSTRACT FROM AUTHOR]

Manipulation of quantum optical pulses, such as single photons or entangled photon pairs, enables numerous applications, from quantum communications and networking to enhanced sensing. Common methods to shape laser pulses based upon filtering or amplification cannot be employed with quantum light pulses as these approaches introduce detrimental loss and noise to the system. Here, methods to control and measure quantum light pulses based upon deterministic application of targeted phases in time and frequency domains are reviewed, along with recent demonstrations of quantum applications. [ABSTRACT FROM AUTHOR]