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The growing demand for wireless communication in biomedical engineering has opened new research frontiers. This paper introduces an innovative miniaturized ( $4\times 9$ mm2) multiple-input multiple-output (MIMO) circularly polarized (CP) implantable antenna for a wireless capsule endoscopy (WCE) system. The presented device features two Hilbert curve-shaped meandered resonators. The space-filling characteristic inherent in the Hilbert curve contributes to miniaturization and bandwidth enhancement of up to 250 MHz to cover possible detuning between diverse organs. Simultaneously, employing the curve’s inherent natural symmetry and adopting an orthogonal port arrangement led to a noteworthy improvement in isolation up to 27 dB with an enhanced gain of −27.9 dBi. Comprehensive simulation analysis of antenna-integrated WCE systems in homogeneous and hetrogenous environments is conducted in the stomach, small intestine, and large intestine. Without the need for an external decoupling structure, the system demonstrated good MIMO characteristics with isolation of 27 dB. A fabricated prototype has been tested in a saline solution and minced pork. A good match between the measured and simulated results has been observed. At both ports, the axial ratio (

This paper presents a high-speed V-band on-off keying (OOK) modulator in 65 nm CMOS based on distributed transmission lines architecture. The high-speed operation of the proposed OOK modulator is attained by distributing a single large switching transistor into smaller units. The effects of parasitic capacitances of each small switch are mitigated by series inductors, forming an artificial transmission line. The switch size and the number of stages are optimized for a reasonable balance between insertion loss and isolation. Small signal measurement of the OOK modulator reveals 3.8 dB insertion loss and 20.5 dB isolation at 60 GHz, with <5 dB insertion loss and >16 dB on-off ratio from 50 GHz to 70 GHz. Testing with a modulation setup shows the modulator is fully functional up to 5 Gbps at a 60 GHz carrier. Limitations of the test setup prevent modulation testing at >5 Gbps. The fabricated modulator does not consume any DC power and has an active footprint of 0.025 mm2. [ABSTRACT FROM AUTHOR]

Due to their low energetic photons and lack of ionization damage, terahertz (THz) waves are recognized as suitable for various wireless innovative applications with high-speed data rates. This paper proposes the design and analysis of a microstrip patch antenna based on a dual-ply hexagonal split ring resonator (HSRR). The suggested antenna resonates at 1.9 THz and is suitable for recent advancements in wireless communication. Furthermore, the HSRR structure has been investigated for various spacing Rs values between the rings, and the optimized HSRR structure performance is compared with conventional antennae. The computer simulation technology studio suite was used to model the planned HSRR and to study the antenna properties. The optimized HSRR structure produces − 47.09 dB return loss with a voltage standing wave ratio of 1.008. The structure exhibits a gain of 8.649 dB and a directivity of 8.696 dB at 1.992 THz. THz light's capability to react differently with innocuous and threatening materials as a function of the THz band provides a highly flexible base for spectroscopic THz scanning and security checks. This suggested HSRR antenna is appropriate for all THz applications with high-speed data rates, such as wireless satellite communication, the biomedical detection of malignant tissue, THz imaging, and spectrometers. [ABSTRACT FROM AUTHOR]

Compared with traditional radio frequency communication, petahertz communication (PetaCom) enjoys several distinct advantages including high data rate, low latency and high determinacy, exhibiting essential application potential in industrial internet of things (IIoT).However, IIoT oriented PetaCom suffers issues of link instability and interference in real scenarios.Starting from the basic concepts of IIoT and PetaCom, a comprehensive summary of IIoT oriented PetaCom was presented including channel modeling, physical-layer technologies, user networking, advantages and challenges.The goal is to provide guidance for relevant researches on IIoT oriented PetaCom in the future.

A high-data-rate $D$ -band transmitter (TX) module cointegrating a dual-channel TX integrated circuit (IC) in 45-nm CMOS partially deplated silicon-on-insulator (PDSOI) technology and an antenna is presented. The proposed system-in-package is based on an innovative channel-bonding technique and is fabricated using a low-cost printed circuit board process. The IC consists of two upconversion chains, including on-chip millimeter-wave local oscillator generators. The emitted signal is composed of eight channels, each one having 2.16-GHz bandwidth, organized in two sets of four channels at the intermediate frequency (IF) band (around 61.56 GHz) that are upconverted to two adjacent subbands centered at 148 GHz. Then, the two subband signals are combined off-chip using a substrate integrated waveguide diplexer and radiated by a patch antenna array realized on the same package. The output spans from 139.3 to 156.6 GHz. The total equivalent isotropic radiated power is 8.3 dBm. An 84.48-Gb/s data rate is achieved with 64-QAM. The module consumes 600 mW from a 1-V supply and occupies a compact area of 12 $\times $ 6 mm2. [ABSTRACT FROM AUTHOR]

Based on Orthogonal Chaotic Vector Shift Keying (OCVSK) system and Multilevel Code-Shifted Differential Chaos Shift Keying (MCS-DCSK) system, a new Multilevel Code-Shifted Differential Chaos Shift Keying (OMCS-DCSK) modulation system is proposed and designed in this paper. New orthogonal chaotic signal sets are generated using Gram-Schmidt algorithm and Walsh code function then these signals are used for bearing information bits to achieve higher data rate and better bandwidth efficiency compared with the conventional DCSK communication system. The bit error rate (BER) analysis of the OMCS-DCSK system over additive white Gaussian noise (AWGN) and multipath Rayleigh fading channel is derived and compared with the simulation results. Also, the spectral and complexity analysis of the system are presented and compared with the conventional DCSK systems. The results show that the proposed system outperforms OCVSK and MCS-DCSK in BER performance and spectral efficiency

This paper presents a novel, digitally configurable, switching oscillator-based impulse radio ultra-wideband (IR-UWB) transmitter that is robust to process variations. The pulse width and pulse position properties of the output waveform are configurable to ensure operation for the desired bandwidth and output pulse energy values. The architecture is based on a cross-coupled LC voltage-controlled oscillator (LC VCO) implemented with a custom-designed on-chip balun at a center frequency of 2.4 GHz. With the usage of this on-chip balun, the need for an extra buffer stage is eliminated, and the highest possible efficiency is achieved with the proper turns ratio selected. The generated digital control pulse signals are also used to ensure fast start-up and UWB operation while maintaining low power consumption with an implemented on/off tail switching scheme. The presented IR-UWB transmitter that occupies a total area of 0.35 mm2 is fabricated in the United Microelectronics Corporation (UMC) 180-nm mixed-mode/radio frequency (RF) CMOS process. The measured output voltage swing of the fabricated transmitter is 0.812 V on a 50- Ω load for the 200 Mb/s data rate, and the bandwidth is measured as 902 MHz. The achieved frequency tuning range is 1 GHz and the fabricated transmitter can drive 50 Ω , 75 Ω and 100 Ω loads with measured efficiency values 4.16%, 5.76%, and 4.05%, respectively. Compared to other works in the literature, this design achieves a higher output pulse energy at a higher data rate while maintaining low power consumption and, thus, high efficiency. • IR-UWB transmitter that features configurable pulse width, pulse position, and center frequency settings, designed to withstand PVT variations. • A custom-designed balun designed for maximum efficiency, eliminating the necessity for an output stage to drive a 50- Ω , 75- Ω , or 100- Ω loads. • Achieving high efficiency through the combination of high data rate and large output voltage swing while maintaining low power consumption. • Fast start-up and shutdown using configurable charge injection and charge removal from the output of the oscillator circuit. [ABSTRACT FROM AUTHOR]

The carrier index differential chaos shift keying (CI-DCSK) modulation scheme transmits one reference and a single data-bearing wavelet over different subcarriers within one symbol duration, resulting in a limited bit rate and low spectral efficiency. In this brief, a novel CI-DCSK modulation scheme is proposed by transmitting multiple data-bearing wavelets together with one reference in a parallel way. Different Walsh codes are applied to separate these data-bearing wavelets so that they can share some subcarriers for index modulation and wavelet transmission. By removing or adding some data-bearing wavelets, the proposed scheme can achieve a high and adaptive data rate with better spectral and energy efficiencies. Furthermore, redundancies in the structure of transmitted signals can be exploited for noise reduction. Analytical bit error rate expressions of the proposed system are derived over the AWGN and the multipath Rayleigh fading channels, respectively. Finally, relevant simulations are performed for verification. [ABSTRACT FROM AUTHOR]

In this paper multiple papers and the various characteristics of extremely wide band antennas and the applications of the same are analysed and compared. With a view to identify the benefits of usage of Extremely wideband antennas for high data rate application, this paper considers various studies that have been meticulously carried out in this area and summarizes for researchers to get a comprehensive view on various extremely wideband antennas and the design aspects. [ABSTRACT FROM AUTHOR]

The paper analyzes the effect of structure inherent to optoelectronic radiotransmitting modules of a phased array antenna (PAA) on the noise characteristics in the millimeter range (MMR) of waves. Considered are promising structures of MMR modules for generating radiation with a phased array for communication systems based on optoelectronic technologies. The promising types of photodiodes that are used to form MMR radio signals as well as the distance and physical limitations for photodetectors associated with a limited bandwidth and nonlinear response characteristics have been analyzed. Mathematical modeling of the oscillation of the output current after the optoelectronic conversion of the signal and noise characteristics of the radio-transmitting modules capable to form MMR radiation in PAA has been carried out. The analysis of the nonlinearity of the sensitivity of photodiodes in the high-frequency regions of formation of radio signals has been carried out. The necessity to structurally optimize optoelectronic components in the MMR transmission module has been shown depending on the noise characteristics of the output signal. It has been shown that fundamental studies of nonlinear characteristics and factors limiting the band of photodetectors are important tasks for further developing MMR telecommunications of the next generations. [ABSTRACT FROM AUTHOR]

In this article, a body channel communication (BCC) transceiver (TRX) and low-power receiver (RX) that can cover wide applications are proposed. The IEEE 802.15.6 human body communication (HBC) physical layer (PHY) standard and high-speed data transmission are supported simultaneously with a single chip. First, the sinusoidal-modulated transmitter is proposed for the standard mode TRX, and it can reduce filtering power overhead 35%. Second, high-speed TRX is proposed that can support dual-band QPSK modulation to increase system data rate and bandwidth efficiency. Third, on-chip RC duplexer is proposed for full-duplex function in communication. Also, for the low-power RX, a wireless power transfer (WPT)-based wake-up receiver (WuRX) and a higher energy efficiency main RX is integrated into RX chip. The main HBC RX demodulates both ASK and frequency-shift keying (FSK) information with a sharing oscillator (OSC) with 31- $\mu \text{W}$ low-power consumption. The TRX and RX are implemented in 65-nm CMOS process. [ABSTRACT FROM AUTHOR]

Altimetry data of two and a half years (June 2016–November 2018) of Sentinel-3A SRAL (S3A-SRAL) were validated at the sampling frequency of 80 Hz. The data were obtained from the European Space Agency (ESA) Grid Processing On Demand (GPOD) service over three coastal sites in Spain: Huelva (HU) (Gulf of Cádiz), Barcelona (BA) (Western Mediterranean Sea), and Bilbao (BI) (Bay of Biscay). Two tracks were selected in each site: one ascending and one descending. Data were validated using in situ tide gauge (TG) data provided by the Spanish Puertos del Estado. The altimetry sea level anomaly time series were obtained using the corrections available in GPOD with the exception of the sea state bias (SSB) correction, not available at 80 Hz. Hence, the SSB was approximated to 5% of the significant wave height (SWH). The validation was performed using two statistical parameters, the Pearson correlation coefficient (r) and the root mean square error (rmse). In the 5–20-km segment with respect to the coastline, the results were 6–8 cm (rmse) and 0.7–0.8 (r) for all the tracks. The 0–5-km segment was also analyzed in detail to study the land effect on the altimetry data quality. The results showed that the track orientation, the angle of intersection with the coast, and the land topography concur to determine the nearest distance to the coast at which the data retain a similar level of accuracy than in the 5–20-km segment. This “distance of good quality” to shore reaches a minimum of 3 km for the tracks at HU and the descending track at BA. [ABSTRACT FROM AUTHOR]

In this paper, we present a high data rate implementation of a digital predistortion (DPD) algorithm on a modern mobile multicore CPU containing an on-chip GPU. The proposed implementation is capable of running in real-time, thanks to the execution of the predistortion stage inside the GPU, and the execution of the learning stage on a separate CPU core. This configuration, combined with the low complexity DPD design, allows for more than 400 Msamples/s sample rates. This is sufficient for satisfying 5G new radio (NR) base station radio transmission specifications in the sub-6 GHz bands, where signal bandwidths up to 100 MHz are specified. The linearization performance is validated with RF measurements on two base station power amplifiers at 3.7 GHz, showing that the 5G NR downlink emission requirements are satisfied. [ABSTRACT FROM AUTHOR]

A new multicarrier $M$ -ary orthogonal chaotic vector shift keying with index modulation (MC-MOCVSK-IM) is presented in this paper. In this design, information bits are conveyed not only by the multiple groups of $M$ -ary information bearing signals, but also by the specific indices of the selected reference signals which depend on the incoming mapped bits. Benefiting from the favorable features of multicarrier modulation, $M$ -ary modulation and index modulation, MC-MOCVSK-IM system is capable to offer higher energy efficiency and spectral efficiency at some expense of hardware complexity. In addition, the analytical bit error rate (BER) expressions of MC-MOCVSK-IM system are derived over additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels. The BER performance comparison between MC-MOCVSK-IM system and other non-coherent chaotic communication systems is carried out to highlight the superiority of MC-MOCVSK-IM system in terms of BER performance. Considering the dramatically increased demand for high-data-rate transmission and the harsh environment of future wireless communication, MC-MOCVSK-IM system shows strong robustness and offers competitive solutions for high-data-rate non-coherent chaotic communication systems. [ABSTRACT FROM AUTHOR]

A new $M$ -ary differential chaos shift keying with index modulation (IM-MDCSK), which has the advantages of high data rate and low energy consumption, is proposed in this paper. In the proposed scheme, each data frame is divided into several time slots where the reference signal is placed in the first time slot and the rest time slots with specific indices are provided for information bearing signals. More exactly, the information bearing signals with active indices are modulated by $M$ -ary DCSK symbols, and the active indices are determined by mapped bits via the combination number mapping method. At the receiver, the absolute values of decision variables in all branches are used to find the indices of active time slots, while $M$ -ary DCSK demodulation is applied to recover the modulated bits. Moreover, we derive the analytical bit-error-rate (BER) expressions for the proposed scheme over additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels, and then simulation results verify our theoretical derivations. Finally, the performance of IM-MDCSK scheme is compared with $M$ -ary DCSK and other up-to-date chaotic modulation schemes based on index modulation (IM). IM-MDCSK scheme is proved to be competitive and preeminent. [ABSTRACT FROM AUTHOR]

This paper proposes a variable gain amplifier (VGA) with reconfigurable DC-offset cancellation (DCOC) for multi-standard applications. In this design, a cell-based design method and some bandwidth extension technologies are adopted to achieve a high data rate and a wide gain control range simultaneously. In addition, the DCOC having a tunable lower-cutoff frequency can make an optimum compromise between BER and SNR according to the specified baseband standard. The measurements show that the VGA achieves a gain control range from -6 dB to 60 dB, a bandwidth beyond 3 GHz, and a tunable lower-cutoff frequency from 0 to 300 kHz. When entering a 223-1 pseudo-random bit sequence signal at 5 Gb/s, the VGA consumes 17 mW from a 1.2-V supply and the output data peak-to-peak jitter is less than 40 ps. The VGA is fabricated in a 90-nm CMOS process with a chip size (including all pads) of 0.52 × 0.5 mm2.

In this paper, a new multicarrier based DCSK system that is combined a wavelet packet modulation (WPM) with differential chaos shift keying (DCSK) and named WPM–DCSK is proposed. WPM–DCSK system is an extension of orthogonal frequency division multiplexing OFDM–DCSK system that aims to replace the fast Fourier transform in OFDM system with wavelet packet transform and improves the spectral efficiency by removing the cyclic prefix and reduced the complexity by using real operation instead of complex operation. WPM–DCSK system has all the benefit of OFDM–DCSK and furthermore improves the limitations and drawbacks of it. The data rate improvement, the energy saving improvement and data-energy- to-bit-energy-ratio factors are derived and compared with DCSK and OFDM–DCSK systems. The validity of the derived analytic expression of the bit error rate of the proposed system is confirmed by the simulation under an additive white Gaussian noise channel. [ABSTRACT FROM AUTHOR]

In this paper, a dual-mode differential chaos shift keying with index modulation (DM-DCSK-IM) is proposed. In the proposed system, the bit stream is partitioned into two subblocks, where the first subblock is the mapped bits used to select the active time slot, which presents the time slot’s constellation mode, and the second subblcok is the modulated bits, which are further divided into two groups and modulated by a pair of distinguishable modem-mode constellations, respectively. Unlike the recently proposed pulse-position-modulation differential chaos shift keying (PPM-DCSK), since both the active and inactive time slots are applied to convey the information bits, the data rate of the proposed system can be promoted significantly. In order to detect the active time slots and recover the mapped bits as well as modulated bits correctly, we propose an effective detection algorithm for the proposed system. Furthermore, the theoretical bit error rate (BER) expressions are derived over additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels, and the simulation results validate the accuracy of our derivations. Finally, the BER performance of the proposed system is compared with the other non-coherent chaotic communication systems, and the results indicate that the proposed system can offer competitive and satisfactory BER performance. [ABSTRACT FROM AUTHOR]

In this brief, a multilevel code shifted differential chaos shift keying system with ${M}$ -ary modulation (MCS-MDCSK) is proposed, which is a hybrid of the ${M}$ -ary modulation and multilevel code shifted differential chaos shift keying. In the proposed system, since the reference signal and a number of different information bearing signals which can carry ${M}$ -ary constellation symbols are transmitted in the same slot, the spectral efficiency of MCS-MDCSK system is enhanced significantly. By combining with ${M}$ -ary modulation, MCS-MDCSK system makes great progress in pursuit of higher data rate. Moreover, we derive the analytical bit-error-rate (BER) for the proposed system over the additive white Gaussian noise and multipath Rayleigh fading channels, and we verify our theoretical derivations by simulations. Finally, the BER performance of the proposed system is compared with other non-coherent chaotic modulation systems and MCS-MDCSK system is found to be superior and competitive. [ABSTRACT FROM AUTHOR]

To solve the problems of space modulation antenna utilization and generalized spatial modulation transmission rate are low. This paper proposed a generalized space code joint index modulation, which combined generalized spatial modulation and code index modulation. It respectively mapped information bits into a (pseudo noise) PN code index, an antenna index and a modulation symbols after series-to-parallel conversion at the transmitting end. The real and imaginary parts of the modulation symbols respectively selected the activated pseudorandom code to spread spectrum, and transmitted the signals through an activated antenna combination. The combination of generalized spatial modulation and code index modulation improved the transmission rate of the system and the utilization of the antenna. In addition, it significantly enhanced the antijamming performance. The analysis and simulation results show that GSCJIM saves index resource more than generalized space modulation at the same transmission rate, and it has the performance advantage of 5 dB when bit error rate is 10-3. [ABSTRACT FROM AUTHOR]

To deal with the problem that CIM should consume a lot of pseudo noise (PN) code resources when it increased the information transmission rate by increasing the number of mapping bits. This paper proposed a novel generalized code index modulation (GCIM). It divided the information bits of the transmitter into mapped bits and modulation bits and mapping modulation bits and mapped bits into modulation symbol and the indexes of the PN code groups respectively. The in-phase part and the orthogonal part of the modulation symbol spread spectrum by selecting activate PN code group respectively. What’s more, by increasing the number of the activate PN code of per transmission slot, which could increase the number of mapped bits and improved the spectral efficiency and energy efficiency of the system. The simulation results show that it is not better than CIM about 2 dB in the additive white Gaussian noise channel and about 1 dB in the Rayleigh fading channel at the same spectral efficiency. Nevertheless, compared with CIM, GCIM consumes significantly less PN code resources. [ABSTRACT FROM AUTHOR]

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A small form-factor, lightweight wireless capsule endoscope (WCE) system with body channel communication (BCC) transceiver ICs is proposed for VGA-resolution image transferring and capsule localization. The transceiver ICs are composed of capsule chip and receiver chip, implemented in a 65-nm CMOS process. In the capsule side, the proposed system provides 360° image capturing through four-camera integration to reduce the miss rate. Also, a dual-band pulse-shaping BCC transmitter is proposed to enable low-power (<1 mW), high-speed (80 Mb/s) image transmission. In the receiver side, contact attenuation compensated-received signal strength indicator (CAC-RSSI) is proposed to increase the capsule localization accuracy. The external system is composed of eight-receiver nodes that allow signal demodulation and localization of the capsule. To reduce transceiver payload and system power consumption, image encoder is implemented in the capsule. The transceiver IC is integrated into the capsule system and verified with body mimicking phantom. The proposed system satisfies compatibility with medical grade diagnosis by operating longer than 8 h with 4 fps and 12 h with 2 fps with conventional two silver oxide 55-mA · h coin batteries. The tested localization accuracy shows less than sub-centimeter range. [ABSTRACT FROM AUTHOR]