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Wideband radio frequency (RF) channelization is essential for the reception and detection of cross-band RF signals in various applications, including communications, radar, and spectrum sensing. However, digital channelizers are inefficient at performing RF channelization over a working bandwidth above 10 GHz. Meanwhile, current photonic RF channelizers face challenges in simultaneously considering a wideband, multi-channel, and a high crosstalk suppression ratio. In this work, we proposed and demonstrated a wideband image-reject RF channelization scheme based on integrated dual-soliton microcombs. The dual-soliton microcombs are used for RF spectral copies and heterodyne detection, respectively. Supported by image-reject mixers, the RF channelization is verified with an 8–37 GHz working bandwidth, a 1.2 GHz channel bandwidth, and 25 channels. The image suppression ratio is higher than 34 dB for single-tone signals and 20 dB for wideband signals. Our approach provides an innovative architecture of integrated photonic RF channelizers with high performance, which can benefit a wide range of RF applications by miniaturizing the systems. [ABSTRACT FROM AUTHOR]

Background and Objectives: In this paper, a novel structure as a Folded-Mirror (FM) Trans-impedance Amplifier (TIA) is designed and introduced for the first time based on the combination of the current-mirror and the folded-cascade topologies. The trans-impedance amplifier stage is the most critical building block in a receiver system. This novel proposed topology is based on the combination of the current mirror topology and the folded-cascade topology, which is designed using active elements. The idea is to use a current mirror topology at the input node. In the proposed circuit, unlike many other reported designs, the signal current (and not the voltage) is being amplified till it reaches the output node. The proposed TIA benefits from a low input resistance, due to the use of a diode-connected transistor, as part of the current mirror topology, which helps to isolate the dominant input capacitance. So, as a result, the data rate of 5Gbps is obtained by consuming considerably low power. Also, the designed circuit employs only six active elements, which yields a small occupied chip area, while providing 40.6dBΩ of trans-impedance gain, 3.55GHz frequency bandwidth, and 664nArms input-referred noise by consuming only 315µW power using a 1V supply. Results justify the proper performance of the proposed circuit structure as a low-power TIA stage. Methods: The proposed topology is based on the combination of the current mirror topology and the folded-cascade topology. The circuit performance of the proposed folded-mirror TIA is simulated using 90nm CMOS technology parameters in the Hspice software. Furthermore, the Monte-Carlo analysis over the size of widths and lengths of the transistors is performed for 200runs, to analyze the fabrication process. Results: The proposed FM TIA circuit provides 40.6dBΩ trans-impedance gain and 3.55GHz frequency bandwidth, while, consuming only 315µW power using a 1V supply. Besides, as analyzing the quality of the output signal in the receiver circuits for communication applications is vital, the eye-diagram of the proposed FM TIA for a 50µA input signal is opened about 5mV, while, for a 100µA input signal the eye is opened vertically about 10mV. So, the vertical and horizontal opening of the eye is clearly shown. Furthermore, Monte-Carlo analysis over the trans-impedance gain represents a normal distribution with the mean value of 40.6dBΩ and standard deviation of 0.4dBΩ. Also, the value of the input resistance of the FM TIA is equal to 84.4Ω at low frequencies and reaches the value of 75Ω at -3dB frequency. The analysis of the effect of the feedback network on the value of the input resistance demonstrates the input resistance in the absence of the feedback network reaches up to 1.4MΩ, which yields the importance of the existence of the feedback network to obtain a broadband system. Conclusion: In this paper, a trans-impedance amplifier based on a combination of the current-mirror topology and the folded-cascade topology is presented, which amplifies the current signal and converts it to the voltage at the output node. Due to the existence of a diode-connected transistor at the input node, the input resistance of the TIA is comparatively small. Furthermore, four out of six transistors are PMOS transistors, which represent less thermal noise in comparison with NMOS transistors. Also, the proposed Folded-Mirror topology occupies a relatively small area on-chip, due to the fact that no passive element is used in the feedforward network. Results using 90nm CMOS technology parameters show 40.6dBΩ trans-impedance gain, 3.55GHz frequency bandwidth, 664nArms input-referred noise, and only 315µW power dissipation using a 1volt supply, [ABSTRACT FROM AUTHOR]

In this paper, the method for the design automation of a narrow band-pass amplifier, and hence the amplifier tuned oscillator is discussed. A fixator approach is utilized in this method to design the narrow band-pass amplifiers and a reference circuit is required for this process. The fixator–norator pair helps to generate an extra sub-circuit, generally the feedback network; the addition of this sub-circuit in the actual amplifier circuit will modify the frequency response of the amplifier. The amplifier now behaves like an active narrow band-pass filter, which exactly follows the frequency response of the model circuit. This can be turned into an oscillator by providing positive feedback. Such a circuit possesses independent frequency and amplitude control. Hence, the re-designed circuit can be employed as an active filter or an oscillator at the selected center frequency. In addition to the technical merits, the proposed method has pedagogical importance. Few case studies are worked out in this paper to demonstrate the method. [ABSTRACT FROM AUTHOR]

This paper investigates an optimization of the conventional relay selection for multirelay environments. In contrast with previously reported selection schemes, where a selected relay accesses the channel in a dedicated cooperative slot, the proposed scheme recovers the bandwidth loss of the half-duplex constraint by allowing two relays to simultaneously access the channels. Based on an appropriate dirty-paper coding (DPC) technique among relays, the proposed scheme enables a relay to establish communication with the destination at the same time that another relay forwards the data from the source. It is proven that the interplay between relay selection and the superposition DPC weight factor provides a tradeoff between relaying and new data performance. Hence, an appropriate codesign of the superposition DPC parameter and opportunistic relay selection can achieve efficient communication for the new data without affecting the relaying performance. The proposed scheme is compared with conventional relaying approaches, and its enhancements are provided through theoretical studies and numerical results. [ABSTRACT FROM AUTHOR]

In modern companies, the functions of divisions, departments and staff are provided by telecommunication transmitting analog and digital unit information via SCS. Such cable system refers to the use of copper or optical cable networks, passive and active switching devices. Structured cabling system or abbreviated SCS is a complex set of cable trunks and switching equipment that provide the transfer of various types of media data (audio, video, computer data) and is the basis for the operation and integration of telephone, local computer networks, security systems and other services. Many modern systems of security or communications today integrate a wide variety of interfaces into their arsenal, greatly expanding their capabilities and performance. In this paper a smart model based on high-speed communication network with the help of structured cabling system (SCS). Here the speed and bandwidth play the major role. The proposed system focused the highspeed communication between sender and receiver with some higher bandwidth optimization. [ABSTRACT FROM AUTHOR]

A wideband Rayleigh fading channel is considered with causal channel state information (CSI) at the transmitter and no receiver CSI. A simple orthogonal code with energy detection rule at the receiver (similar to pulse position modulation in IEEE Trans. Inf. Theory, vol. 46, no. 4, Apr. 2000 and IEEE Trans. Inf. Theory, vol. 52 no. 5, May 2006) is shown to achieve the capacity of this channel in the wideband limit. This strategy transmits energy only when the channel gain exceeds a threshold, hence only needs causal transmitter CSI. In the wideband limit, this capacity without any receiver CSI is the same as the capacity with full receiver CSI, which is proportional to the logarithm of the bandwidth. Similar threshold-based pulse position modulation is shown to achieve the capacity per unit cost of the dirty-tape channel (dirty paper channel with causal transmitter CSI and no receiver CSI), which equals its capacity per unit cost with full receiver CSI. Then, a general discrete channel with i.i.d. states is considered. Each input has an associated cost and a zero cost input “0” exists. The channel state is assumed to be known at the transmitter in a causal manner. Capacity per unit cost is found for this channel and a simple orthogonal code is shown to achieve this capacity. Later, a novel orthogonal coding scheme is proposed for the case of causal transmitter CSI and a condition for equivalence of capacity per unit cost for causal and noncausal transmitter CSI is derived. [ABSTRACT FROM PUBLISHER]

In this paper, a novel stacked wideband differentially feed antenna with dual polarizations is designed for base station. The circular parasitic patch deepens the resonance depth by slotting. Two linear dipoles are placed at ±45 - under the circular parasitic patch to reduce the overall size of the antenna. The antenna introduces a cross-shaped differential feed to achieve high port isolation. Finally, the designed antenna is fabricated and tested. The test results show that the differential reflection coefficient |Sdd11| is more than 15 dB. The antenna achieves a differential impedance bandwidth of 53.1% (1.63 GHz-2.8 GHz). The isolation is greater than 42 dB over the entire operating bandwidth. The antenna also has a stable gain of 8.2 ± 0.4 dBi and a half-power beamwidth of 65° ± 4°. [ABSTRACT FROM AUTHOR]

In the era of DevOps, developing new toolsets and frameworks that leverage DevOps principles is crucial. This paper demonstrates how Ansible's powerful automation capabilities can be harnessed to manage the complexity of Kubernetes environments. This paper evaluates efficiency across various CNI (Container Network Interface) plugins by orchestrating performance analysis tools across multiple power profiles. Our performance evaluations across network interfaces with different theoretical bandwidths gave us a comprehensive understanding of CNI performance and overall efficiency, with performance efficiency coming well below expectations. Our research confirms that certain CNIs are better suited for specific use cases, mainly when tuning our environment for smaller or larger network packets and workload types, but also that there are configuration changes we can make to mitigate that. This paper also provides research into how to use performance tuning to optimize the performance and efficiency of our CNI infrastructure, with practical implications for improving the performance of Kubernetes environments in real-world scenarios, particularly in more demanding scenarios such as High-Performance Computing (HPC) and Artificial Intelligence (AI). [ABSTRACT FROM AUTHOR]

Torsional oscillations bound the velocity loop bandwidth (BW) of industrial drives and servo systems, deteriorating the transient response to commands and disturbances. This is especially harmful in multidrive systems like paper machines that need to run synchronized. This paper presents two methods to dynamically compensate the torsional oscillations produced by the compliant components between the motor and the load: either a notch filter or an acceleration feedback based on the rigid-body Luenberger observer. The evaluation includes the effect of reducer backlash, whereby both time and frequency domain responses are used to compare the benefits of each technique in a typical paper machine section. Results show that both methods, if properly tuned, are effective techniques to reduce torsional oscillations and are robust to parameter variations. [ABSTRACT FROM AUTHOR]

The article offers information on research papers that are published in technical journals and conference proceedings. Topics include maximizing lifetime of multiple data aggregation trees in wireless sensor networks; shallow quantum circuits with uninitialized ancillary qubits; and multiperiod Internet Protocol (IP)-over-elastic network reconfiguration with adaptive bandwidth resizing and modulation.

In the paper, a wideband four-way filtering power divider with arbitrary power division ratio and input absorptive feature is proposed. Two sets of coupled lines (CLs) are used to achieve the wideband performance. To obtain absorptive properties, a set of T-type absorption structure consisting of two isolation resistors and a λ/4 short-circuit stub is connected between the two CLs. Meanwhile, high frequency selectivity and good out-of-band rejection are realized by introducing two stepped-impedance resonators. Besides, output impedance matching, isolation, and unequal power distribution are achieved by the power division section in the second stage. In the analysis, the equations are derived by using the method of even-odd mode decomposition and voltage-current method. For demonstration, a prototype is designed, fabricated, and measured with the power distribution ratio of 2 : 1 : 1 : 2. Measurements show that an allfrequency band absorption of 200% is obtained with the 3-dB passband bandwidth of 78.1% and out-of-band rejection of 14 dB. Besides, it also shows 15-dB isolations within more than 60% FBW and has the feature of small size. [ABSTRACT FROM AUTHOR]

Due to the extensively accessible bandwidth of many tens of GHz, millimeter-wave (mmWave) and sub-terahertz (THz) frequencies are anticipated to play a significant role in 5G and 6G wireless networks and beyond. This paper presents investigations on mmWave bands within the indoor environment based on extensive simulations; the study considers the behavior of the omnidirectional and directional propagation characteristics, including path loss exponents (PLE) delay spread (DS), the number of clusters, and the number of rays per cluster at different frequencies (28 GHz, 39 GHz, 60 GHz and 73 GHz) in both line-of-sight (LOS) and non-LOS (NLOS) propagation scenarios. This study finds that the PLE and DS show dependency on frequency; it was also found that, in NLOS scenarios, the number of clusters follows a Poisson distribution, while, in LOS, it follows a decaying exponential distribution. This study enhances understanding of the indoor channel behavior at different frequency bands within the same environment, as many research papers focus on single or two bands; this paper considers four frequency bands. The simulation is important as it provides insights into omnidirectional channel behavior at different frequencies, essential for indoor channel planning. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present cascaded frequency selective surfaces (FSSs) with matryoshka geometry to increase the effective bandwidth. We carry out an analysis of the influence of the spacing between the surfaces on the FSSs frequency response. The application involves a two-layer cascaded FSS, one as a band-stop filter with a matryoshka geometry and the other as a band-pass filter with inverted or negative matryoshka geometry. With this framework, it is possible to extend an ultra-wideband (UWB) of a bandwidth up to 2 GHz in the 1.8 GHz to 3.8 GHz range with just two layers and an air gap of 12 mm, in addition to a bandwidth of 2 GHz to 3.2 GHz with a smaller 4 mm gap between layers. [ABSTRACT FROM AUTHOR]

This paper describes a 2-stage tactic for achieving an odd-order variable-bandwidth (OO-VBW) filter with absolutely guaranteed stability. The design methodology aims to minimize the p-norm amplitude-response error while maintaining the OO-VBW-filter's stability. In order to tune OO-VBW filter's amplitude response, we utilize a kind of functions of the bandwidth (BW)-tuning parameter to express the filter's coefficients. Because those functions have changeable function values, the designed OO-VBW-filter's amplitude response possesses variability. Another important concern in this paper is the stability issue. When the filter coefficient values expressed as function values are changed, the OO-VBW filter that has feedback structures may become unstable. This necessitates that the OO-VBW-filter's stability must always be preserved during real-time tuning. In order to stabilize such an OO-VBW filter that has feedback structures, a coefficient-conversion (CC) algorithm is adopted, and it is incorporated into the 2-stage methodology for obtaining the OO-VBW filter. To illustrate both the stability and high approximation accuracy, the design of an OO-VBW bandpass filter is simulated. The simulation details verify that both stability and high accuracy can be successfully achieved. [ABSTRACT FROM AUTHOR]

The atmospheric Unified Model (UM) developed at the UK Met Office is used for weather and climate prediction by forecast teams at a number of international meteorological centres and research institutes on a wide variety of hardware and software environments. Over its 25 year history the UM sources have been optimised for a better application performance on a number of HPC systems including NEC SX vector architecture systems and recently the IBM Power6/Power7 platforms. Understanding the influence of the compiler flags, MPI libraries and run configurations is crucial to achieving the shortest elapsed times for a UM application on any particular HPC system. These aspects are very important for applications that must run within operational time frames. Driving the current study is the HPC industry trend since 1980 for processor arithmetic performance to increase at a faster rate than memory bandwidth. This gap has been growing especially fast for multicore processors in the past 10years and it can have significant implication for the performance and performance scaling of memory bandwidth intensive applications, such as the UM. Analysis of partially used nodes on Intel Xeon clusters is provided in this paper for short and medium range weather forecasting systems using global and limited-area configurations. It is shown that on the Intel Xeon based clusters the fastest elapsed times and the most efficient system usage can be achieved using partially committed nodes. [ABSTRACT FROM AUTHOR]

In this paper, a mode control technology of a slotline resonator is proposed and utilized to guide the design of the slotline resonator. With this method, characteristic modes generated by the slotline resonator are more controllable. With characteristic mode analysis, which is the core of this technology, the desired and unwanted modes of the slotline resonator are easy to be analyzed, controlled, and further used to expand the stopband bandwidth. By applying this technology, a multi-mode slotline resonator with a T-shaped coupling structure (MMSR-T) is proposed by modifying a multi-mode slotline resonator (MMSR), and its unwanted modes out of the passband are more controllable without influencing the expected modes in the passband. Based on the proposed MMSR-T, a balanced bandpass filter (BPF) is proposed, which consists of a U-shaped microstrip/slotline transition as the input/output structure, a T-shaped slotline feeding structure as a feeding terminal, and MMSR-T as the filtering unit. Through the mode analysis and design of MMSR-T, ultra-wide differential-mode (DM) stopband, high common-mode (CM) suppression, and high DM selectivity are obtained in this design. The measured results agree well with the theoretical predictions and simulated results. The effects of mode control technology on stopband extension are proven. [ABSTRACT FROM AUTHOR]

PD measurements in dielectric liquids have been normally performed in the past only using conventional narrow bandwidth detectors. The more recent use of ultra-wide bandwidth instruments has permitted to support once again the thesis that the PDs in oils are the consequence of the streamer (vapor phase) formation and its development. In the paper simultaneous PD measurements in insulating liquids using both narrow and ultra-wide bandwidth detectors are presented. Whilst PD detection with narrow bandwidth instruments gives only integrated signals, the use of ultra-wide bandwidth techniques permits to have much more precise information on PD phenomena, which appear to be in the form of pulses (bursts) of ascending magnitude as the bubble within the liquid expands in volume. As reported in the paper, the use of the ultra-wide bandwidth instruments permits also to distinguish the PD pulses occurring in regular voids of oil-paper insulations and PD pulses formed directly in the liquids as consequence of the streamer development. Also in the paper the meaning of the PDIV in oils is discussed, showing its dependence with the definition used, the unpredictable level of the background noise as well as the randomness of the PD initiation process. [ABSTRACT FROM AUTHOR]

A 360° video offers a more immersive experience, gaining increasing popularity among users. However, enhancing the transmission efficiency of 360° videos under limited bandwidth conditions remains a significant challenge. This paper segments the video into three areas: the attention area, the edge area, and the viewpoint-switching transition area. Based on the segmentation of these three distinct video areas, a novel non-uniform coding transmission method for 360° videos is presented, along with mathematical modeling to define the optimization problem. A heuristic algorithm is subsequently introduced, which adaptively determines the optimal number of tiles and allocates the bitrate for each tile in real time to enhance the user's quality of experience (QoE). Finally, a simulation platform has been developed to validate the efficacy of the proposed algorithm by conducting comparative analyses with existing algorithms. [ABSTRACT FROM AUTHOR]

This paper explores the potential of an Integrated Sensing and Communication (ISAC) system to enhance search-and-rescue operations. While prior research has explored ISAC capabilities in Unmanned Aerial Vehicles (UAVs), our study focuses on addressing the specific challenges posed by modern communication standards (e.g., power, frequency, and bandwidth limitations) in the context of search-and-rescue missions. The paper details effective methods for processing echoed signals generated by downlink transmissions and evaluates key performance indicators, including Noise Equivalent Sigma Zero (NESZ) and channel capacity. Additionally, we utilize synchronization uplink signals transmitted by User Equipment (UE) to improve target detection and classification of possible victims by fusing SAR imagery with triangulation results from uplink signals. An experimental campaign validates the proposed setup by integrating SAR images of the environment with active localization results, both produced by a UAV equipped with a Software Defined Radio (SDR) payload. Our results demonstrate the system's capability to detect and localize buried targets in avalanche scenarios, with localization errors ranging from centimeters to 10 m depending on environmental conditions. This successful integration highlights the practical applicability of our approach in challenging search-and-rescue missions. [ABSTRACT FROM AUTHOR]

In order to solve the requirements of multi-channel communication applications, this paper proposes a miniaturized dualpassband substrate integrated waveguide filter with asymmetric passband response. The design uses a half-mode substrate integrated waveguide (HMSIW) cavity, which is loaded with a back-to-back complementary open resonant ring (CSRR) according to the vanishing mode propagation theory to generate a passband response lower than the HMSIW basic mode TE101, further reducing the cavity size. In addition, the band-resistive characteristics of the single-ring structure of the CSRR resonator are analyzed, and a C-slot is added at the feeder to improve the out-of-band characteristics of the second passband. Through simulation optimization and testing, the center frequency of the dual-passband filter is 4.05 GHz/8.64 GHz; the relative bandwidth is 16%/44%, the insertion loss of both passbands is better than 0.8 dB; the physical test results are consistent with the simulation ones; and the size of the filter is only 0.42λg × 0.14λg. It shows that the proposed filter has the characteristics of small size and low loss, and can be widely used in multi-channel RF front-end systems in the field of wireless communication. [ABSTRACT FROM AUTHOR]

GPUs are commonly used to accelerate the execution of applications in domains such as deep learning. Deep learning applications are applied to an increasing variety of scenarios, with edge computing being one of them. However, edge devices present severe computing power and energy limitations. In this context, the use of remote GPU virtualization solutions is an efficient way to address these concerns. Nevertheless, the limited network bandwidth might be an issue. This limitation can be alleviated by leveraging on-the-fly compression within the communication layer of remote GPU virtualization solutions. In this way, data exchanged with the remote GPU is transparently compressed before being transmitted, thus increasing network bandwidth in practice. In this paper, we present the implementation of a parallel compression pipeline designed to be used within remote GPU virtualization solutions. A thorough performance analysis shows that network bandwidth can be increased by a factor of up to 2×. [ABSTRACT FROM AUTHOR]

The paper proposes an ultra-wideband frequency selective rasorber (FSR) with low infrared emissivity for the composite detection threat of both radars and infrared sensors. Firstly, the equivalent circuit (EC) method based on transmission line (TL) theory is utilized to analyze the absorption/transmission conditions. Then, based on the analysis above, sinusoidal microstrip lines with non-frequency-varying characteristics are adopted in the design, which significantly enhances the transmission bandwidth of FSR. The FSR demonstrates an absorption band ranging from 2.65 GHz to 8.80 GHz and a transmission band ranging from 9.15 GHz to 17.71 GHz. Furthermore, an infrared shielding layer (IRSL) exhibiting low emissivity in the infrared band and high transmittance in the microwave band is applied to the FSR. The simulation and experiment results verify that the IRSL-FSR demonstrates an ultra-wide transmission band ranging from 9.16 GHz to 17.94 GHz and an ultra-wide absorption band ranging from 2.66 GHz to 8.01 GHz. Additionally, it exhibits a low emissivity value (0.23) in 8–14 μm, providing a viable solution to the formidable challenge of radar-infrared bistealth for satellites and other communication-enabled flying platforms. [ABSTRACT FROM AUTHOR]

This paper presents a fully integrated stacked architecture to address the challenges of 6G application using CMOS analog pre-distortion and tunable neutralization techniques. By using this method for the stacked power amplifier design, a baseband and passband impedance transformation is achieved, that combined with the stacked power amplifier architecture allows for high efficiency in deep back off, with a reduced load modulation for high bandwidth. This project designs an efficient Stacked Power Amplifier (PA) for 6G. The power amplifier is implemented in 180nm CMOS technology using Cadence and ADS tool. The usage of a diode pre-distorter for analog pre-distortion is investigated for the stacked power amplifier design. It is shown that the linearity of the stacked power amplifier has been significantly improved compared to a bipolar transistor at almost no additional layout size. This research work presents design of a Ka band power amplifier for sixth generation (6G) mobile communication in CMOS design. The stacked power amplifier consists of two different stages of architecture. With 5-volt supply, the stacked power amplifier achieves a small-signal gain of 16 dB, saturated output power (Psat) of 18 dBm, and achieves the maximum power added efficiency of 34.79%. The amplifier has been designed in 180-nm CMOS technology. [ABSTRACT FROM AUTHOR]

To enhance the reduction of radar cross section (RCS) and improve stealth performance, a phase cancellation and absorbing metasurface (PCAM) is designed in this paper. The PCAM is composed of a chessboard layout of circular units and square units, and it not only converts absorbed incident electromagnetic waves into heat to reduce the intensity of reflected electromagnetic waves but also simultaneously controls the phase of the reflected electromagnetic waves, achieving phase cancellation. This enables the metasurface to be exhibited with ultralow backscatter. After simulation verification, the metasurface can achieve RCS reduction of over 15 dB in the 4.3-11 GHz range for vertical incidence, with a fractional bandwidth of approximately 87.6% and over 15 dB in the 5.4-11.2 GHz range for a 30° oblique incidence, demonstrating good stability for oblique angles. The metasurface has increased the reduction level from over 10 dB to over 15 dB, significantly enhancing the RCS reduction. Additionally, in the co-planar state with a central curvature of 90°, it can also achieve RCS reduction of over 10 dB in the 3.2-9.9 GHz range, showing significant potential for practical applications. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a scenario in which protected and unprotected services coexist in an elastic optical network under dynamic traffic. In the investigated scenario, unprotected services can reuse the reserved idle bandwidth to provide protection to the protected services. Under this scenario, we propose a new heuristic algorithm that enables such reuse as well as define and introduce a new assignment problem in elastic optical networks, named a Transmission Spectrum Assignment (T-SA) problem. In this paper, we consider a scenario in which services may be routed using the multipath routing approach. Additionally, protection using bandwidth squeezing is also considered. We assess our proposal through simulations on three different network topologies and compare our proposal against the classical protection approach, in which bandwidth reuse is not allowed. For the simulated range of network loads, the maximum (minimum) blocking probability reduction obtained by our proposal is approximately 48% (10%) in the European topology, 46% (7%) in the NSFNET topology, and 32% (6%) in the German topology. [ABSTRACT FROM AUTHOR]

This paper proposes a core and spectrum allocation algorithm for elastic optical networks based on multi-core fibers. In this context, the fragmentation and crosstalk mitigation algorithm (FraCA) is proposed. FraCA implements mechanisms to reduce spectral fragmentation and inter-core crosstalk in the network, proving efficient when compared with six other algorithms reported in the literature. The numerical results show that when compared with the most competitive of the six algorithms, FraCA achieves a gain of request blocking probability of at least 16.87%, a gain of bandwidth blocking probability of at least 43.95%, and a mean increase in spectral utilization of at least 4.36%. [ABSTRACT FROM AUTHOR]

We have developed a fast, spatially direct scanning tunable diode laser absorption spectrometer (dTDLAS) that combines four polygon-mirror based scanning units with low-cost retro-reflective foils. With this instrument, tomographic measurements of absolute 2-D water vapour concentration profiles are possible without any calibration using a reference gas. A spatial area of 0.8m×0.8m was covered, which allows for application in soil physics, where greenhouse gas emission from certain soil structures shall be monitored. The whole concentration field was measured with up to 2.5 Hz. In this paper, we present the setup and spectroscopic performance of the instrument regarding the influence of the polygon rotation speed and mode on the absorption signal. Homogeneous H2O distributions were measured and compared to a single channel, bi-static reference TDLAS spectrometer for validation of the instrument. Good accuracy and precision with errors of less than 6% of the absolute concentration and length and bandwidth normalized detection limits of up to 1.1 ppmv .m. √Hz-1 were achieved. The spectrometer is a robust and easy to set up instrument for tomographic reconstructions of 2-D-concentration fields that can be considered a good basis for future field measurements in environmental research. [ABSTRACT FROM AUTHOR]

The R-Test measures the three-dimensional displacement of a tool center point with respect to a work table in five-axis machine tool, as linear axes are driven synchronously with a rotary axis. This paper experimentally compares the measuring performance of the R-Test instruments with (1) tactile linear displacement sensors, (2) laser displacement sensors based on the refraction in a glass ball lens (Laser R-Test), and (3) laser interferometers, in dynamic tests described in ISO 10791-6:2014. A tactile displacement sensor pushes its measuring contact to the target surface by a spring, and its stiffness can limit the measurement bandwidth. This paper experimentally investigates this influence in the measurement of dynamic synchronization error of rotary and linear axes particularly near the reversal point in the present tests. This paper also presents a test to measure the bandwidth of a tactile displacement sensor. [ABSTRACT FROM AUTHOR]

This paper presents a flexible and wearable textile array antenna designed to generate Orbital Angular Momentum (OAM) waves with Mode +2 at 3.5 GHz (3.4 to 3.6 GHz) of the sub-6 GHz fifth-generation (5G) New Radio (NR) band. The proposed antenna is based on a uniform circular array of eight microstrip patch antennas on a felt textile substrate. In contrast to previous works involving the use of rigid substrates to generate OAM waves, this work explored the use of flexible substrates to generate OAM waves for the first time. Other than that, the proposed antenna was simulated, analyzed, fabricated, and tested to confirm the generation of OAMMode +2. With the same design, OAM Mode -2 can be generated readily simply by mirror imaging the feed network. Note that the proposed antenna operated at the desired frequency of 3.5 GHz with an overall bandwidth of 400 MHz in free space. Moreover, mode purity analysis is carried out to verify the generation of OAM Mode +2, and the purity obtained was 41.78% at free space flat condition. Furthermore, the effect of antenna bending on the purity of the generated OAM mode is also investigated. Lastly, the influence of textile properties on OAM modes is examined to assist future researchers in choosing suitable fabrics to design flexible OAM-based antennas. After a comprehensive analysis considering different factors related to wearable applications, this paper demonstrates the feasibility of generating OAMwaves using textile antennas. Furthermore, as per the obtained Specific Absorption Rate (SAR), it is found that the proposed antenna is safe to be deployed. The findings of this work have a significant implication for body-centric communications. [ABSTRACT FROM AUTHOR]

This paper presents the design of a frequency-tunable substrate-integrated waveguide (SIW) band-reject filter, specifically for spectrum underlay cognitive radio operation. The proposed filter has a simple tuning circuit but provides a wide frequency tuning range from 2.9 to 4.4 GHz (41%). The second resonant mode has been suppressed using a simple quadrature coupling; hence, the fundamental mode bandwidth of the filter has been increased from 2.08 GHz to 3.36 GHz. Due to its wide tuning range, simple tuning circuit, and increased fundamental mode bandwidth, the proposed filter is greatly important in underlay cognitive radio construction. The second-order filter has also been developed, and its performance is analyzed with both simulation and measurement. It gives a tunable bandwidth of 41%, an insertion loss of more than 10 dB, and a fundamental mode bandwidth of 3.36 GHz. The filter performance is also analyzed after connecting it to the standard horn antenna. Finally, from the total efficiency plots, it has been concluded that the proposed filter achieves all the above advantages with a low-lossy nature. [ABSTRACT FROM AUTHOR]

In this paper, a 3-bit circularly polarized reconfigurable reflectarray is proposed. The array consists of 64 units in an 8 × 8 configuration, with each unit containing a circular metal patch loaded with phase-delay lines and eight PIN diodes. To independently control each unit, a corresponding DC control circuit was designed and tested with the array. In the bandwidth of 3.43–3.71 GHz, the circularly polarized reconfigurable reflectarray achieved a gain of 16 dB, an aperture efficiency of 27%, an axial ratio of ≤3 dB, an operating bandwidth of 8%, and a beam scanning range of ±60°. The circularly polarized reconfigurable reflectarray can also achieve a good dual-beam radiation performance after testing. The 3-bit circularly polarized reconfigurable reflectarray proposed in this paper offers several advantages, including low loss, high aperture efficiency, a wide beam scanning range, and excellent stability in wide-angle oblique incidence. It has potential applications in low-cost phased array, satellite communications, and deep space exploration. [ABSTRACT FROM AUTHOR]

Microwave hyperspectral instruments represent one of the main atmospheric sounders of China's next-generation Fengyun meteorological satellites. In order to better apply microwave hyperspectral observations in the fields of atmospheric parameter retrieval and data assimilation, this paper analyzes the sensitivity of trace gases to five selected bandwidth channels using a radiative transfer model based on the simulated data of microwave hyperspectral radiances at 50–60 GHz. This method uses information entropy and a weighting function to select channels and analyze the impact of this on the retrieval accuracy of atmospheric profiles before and after channel selection. The experimental results show that channel selection can reduce the number of channels by approximately 74.05% while maintaining a large amount of information content, and this retrieval effect is significantly better than that of MWTS-III. After channel selection, the 10 MHz, 30 MHz, and 50 MHz bandwidths have the best retrieval results in the stratosphere, whole atmosphere, and troposphere, respectively. When considering the number of channels, computational scale, and retrieval results comprehensively, the channel selection method is effective. [ABSTRACT FROM AUTHOR]

Path hopping serves as an active defense mechanism in network security, yet it encounters challenges like a restricted path switching space, the recurrent use of similar paths and vital nodes, a singular triggering mechanism for path switching, and fixed hopping intervals. This paper introduces an active defense method employing multiple constraints and strategies for path hopping. A depth-first search (DFS) traversal is utilized to compute all possible paths between nodes, thereby broadening the path switching space while simplifying path generation complexity. Subsequently, constraints are imposed on residual bandwidth, selection periods, path similitude, and critical nodes to reduce the likelihood of reusing similar paths and crucial nodes. Moreover, two path switching strategies are formulated based on the weights of residual bandwidth and critical nodes, along with the calculation of path switching periods. This facilitates adaptive switching of path hopping paths and intervals, contingent on the network's residual bandwidth threshold, in response to diverse attack scenarios. Simulation outcomes illustrate that this method, while maintaining normal communication performance, expands the path switching space effectively, safeguards against eavesdropping and link-flooding attacks, enhances path switching diversity and unpredictability, and fortifies the network's resilience against malicious attacks. [ABSTRACT FROM AUTHOR]

This paper presents a computer-simulation-based design of an in-line, coaxial-to-circular waveguide adapter for converting the coaxial transverse electromagnetic (TEM) mode to the circular waveguide TE11 mode over more than a one-octave bandwidth. The proposed adapter consists of a coaxial-to-rectangular waveguide transformer employing a stepped-ridge converter and a rectangular-to-circular waveguide transformer employing a curved transition. The proposed adapter has been optimized using a commercial simulation tool. The dimensions of the designed adapter are given so that it can be verified by anyone who is interested. The designed adapter operates from 8.00 GHz to 22.95 GHz (2.87:1 bandwidth) with a reflection coefficient of less than −20 dB and a higher-order mode level of less than −25.0 dB. [ABSTRACT FROM AUTHOR]

Coplanar monopole antennas printed using copper oxide nanoparticles on flexible substrates are characterized in order to study the effect of the ink drop spacing on the antenna parameters. Polyethylene Terephthalate and Epson paper were the chosen flexible substrates, and the antennas were designed to operate at 20GHz. A maximum conductivity of 2.8 × 107 Ω-1m-1 was obtained for the films printed on Polyethylene Terephthalate using a drop spacing of 20 μm. The corresponding antenna achieved a gain and an efficiency of 1.82 dB and 97.6%, respectively. Experiments showed that smaller drop spacings lead to bulging of the printed lines while the antenna performance worsens for longer ones. At the same drop spacing, antennas printed on Epson paper substrate showed a -10 dB return loss bandwidth which extended from 17.9GHz to 23.3GHz, leading to a fractional bandwidth of 26.0%. [ABSTRACT FROM AUTHOR]

Modern data centers use erasure codes to provide high storage efficiency and fault tolerance. Reed–Solomon code is commonly deployed in large-scale distributed storage systems due to its ease of implementation, but it consumes massive bandwidth during node repair. Minimum storage regenerating (MSR) codes is a class of maximum distance separable (MDS) codes that achieve the lower bound on repair bandwidth. However, an exponential sub-packetization level is inevitable for MSR codes, resulting in massive disk I/O consumption during node repair. Disk I/O is becoming the bottleneck of the performance in data centers where the storage system needs to frequently provide high-speed data access to clients. In this paper, we consider disk I/O as an important metric to evaluate the performance of a code and construct MDS array codes with efficient repair under small sub-packetization level. Specifically, two explicit families of MDS codes with efficient repair are proposed at the sub-packetization level of O (r) , where r denotes the number of parities. The first family of codes are constructed over a finite field F q m where q ≥ n is a prime power, m > r (l - 1) + 1 , n and l denote the code length and sub-packetization level, respectively. The second family of codes are built upon a special binary polynomial ring where the computation operations during node repair and file reconstruction are only XORs and cyclic shifts, avoiding complex multiplications and divisions over large finite fields. [ABSTRACT FROM AUTHOR]

The new or future communication systems require much higher flexibility and scalability to support diverse scenarios. In this paper, a high-throughput low-density parity-check (LDPC) decoder on graphics processing unit is presented to meet the flexible and scalable requirements. A memory-reduced forward/backward approach for the check node update is proposed. Moreover, elaborate on-chip memory allocations are conducted to improve memory bandwidth. The proposed (26112, 8448) 5G LDPC decoder on RTX4090 achieves 27.6 Gbps decoding throughput with five layered iterations, while the latency is less than 1 ms. Compared with related works, the throughput speedups obtained by the presented LDPC decoder are from 1.18 × to 12.4 × . [ABSTRACT FROM AUTHOR]

This paper considers UAVs as edge computing nodes and investigates a novel network resource allocation method for federated learning within a three-layer wireless network architecture containing cloud, edges (UAVs), and clients. To address the issue of fair bandwidth resource allocation among clients participating in federated learning, a contribution calculation strategy based on the Shapley value (SV) used as the weight for model aggregation is proposed. On this basis, a client selection and wireless resource allocation method based on model contribution is further designed. By reducing the training and aggregation frequency of the low-contribution clients during the asynchronous aggregation phase, the limited bandwidth resources are allocated to high-contribution clients, thus improving the convergence speed and accuracy of the global model. Simulation experiments demonstrate that the proposed method can significantly reduce the system delay and total energy consumption with gains between 15% and 50% while also improving the final accuracy of the global model by 0.3% and 2% on both short-term and long-term perspectives, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a planar, bow-tie antenna with an enhanced bandwidth and a bi-directional radiation pattern is proposed. The concept of multi-resonance is applied by implementing the superposition of three different bow-tie components with various radii and flare angles in an overlapped fashion into a single element, resulting in a significant increase in bandwidth. The antenna has an electrical size, kr, of 1.10, calculated at the lowest frequency of operation. The proposed antenna is simulated, and a prototype is fabricated for verification by measurement. The result is a wide −10 dB bandwidth of 80.3% (1.23–2.88 GHz) from the measurements. The antenna also maintains a bi-directional radiation pattern, with a negligible difference between the forward and backward realized gains, within the entire −10 dB bandwidth. The measured realized gain values in the forward and backward directions are between 1.5 dBi and 3.7 dBi over the −10 dB bandwidth. The comparison of the measurement and simulation results shows good agreement. [ABSTRACT FROM AUTHOR]

The range resolution of FMCW radar is critical for accurately distinguishing between multiple objects. Higher range resolution allows for better object separation and more precise location determination. While increasing the bandwidth can improve range resolution, it also raises costs and may be subject to regulatory constraints on the available frequency spectrum. This paper proposes an approach to enhance range resolution by increasing the effective bandwidth through signal processing, specifically by introducing the Estimated Signal Padding (ESP) method. ESP extends the bandwidth by lengthening the signal in the time domain, creating a synthesized signal for each target. The proposed algorithm can improve range resolution by a factor of at least 2.25. Unlike existing methods such as Zero Padding and Neural Network Padding, the proposed algorithm can distinguish targets of varying sizes rather than only targets of the same size. The performance of the algorithm has been validated through MATLAB simulations and FMCW radar experiments. [ABSTRACT FROM AUTHOR]

A unified-mode analysis method for modeling symmetric networks is proposed in this paper. Adjusting to the characteristics of Marchand balun circuits, a unified-mode circuit model is constructed by introducing virtual impedance. The tenable condition of a Marchand balun with connecting segments is then derived. The parameter constraint of Marchand balun's input matching is given in a quarter-saddle diagram. Simulated results under different parameter conditions verify the validity of the derived formulas. Based on the derived formulas, the traditional isolation circuit and impedance matching circuit are merged with a Marchand balun to achieve matching for all ports and full-frequency isolation between output ports. A microstrip balun with input and output impedance values of 50 Ω, operating at 1.5 GHz, is simulated, fabricated, and measured. The simulated and measured results of the microstrip balun are in good agreement. When the core parameters remain unchanged, an impedance transformer is inserted in front of the input port of the balun to realize a balun with a topology characterized by flexible impedance transformation. A balun with an input impedance of 35 Ω and different output impedances of 50 Ω and 75 Ω is simulated and fabricated to verify the design concept. Measured results show that an amplitude balance of less than 0.4 dB and a phase balance of less than 3° for a fractional bandwidth of 50%. It should be mentioned that all design equations are closed-form and can be readily employed to design symmetric networks. [ABSTRACT FROM AUTHOR]

Battery-powered Internet-of-Things applications require high-resolution, energy-efficient analog-to-digital converters (ADCs). There are still limited works on sub-MHz-bandwidth ADC designs. This paper presents a sturdy multi-stage shaping (SMASH) discrete-time (DT) delta-sigma modulator (DSM) structure using a self-cascoded floating-inverter-based dynamic amplifier (FIA). The proposed structure removes the explicit quantization error extraction of the first loop and all the feedback DACs in the cascaded loop, decreasing the design complexity of the circuit. This enables the proposed DT DSM to operate at a higher speed, which is suitable for achieving high-order noise at a low oversampling ratio (OSR). The proposed self-cascoded FIA is more power-efficient and can acquire more than 45 dB DC gain under a 1.2 V supply. The DT DSM implemented in a piece of 55 nm CMOS technology measures an 88.0 dB peak signal-to-noise-and-distortion ratio (SNDR) in a 100 kHz bandwidth (BW) and an 85.3 dB dynamic range (DR), consuming 249.1 μW from a 1.2 V supply at 10 MS/s. The obtained 174.0 dB SNDR-based Schreier figure-of-merit (FoMs) is competitive within state-of-art high-resolution (SNDR > 85 dB) and general-purpose (sub-MHz-bandwidth) ΔΣ ADCs. [ABSTRACT FROM AUTHOR]

This paper presents the theory, design, and application of a dual-branch series-diode analog pre-distortion (APD) linearizer to improve the linearity and efficiency of a K-band high-power amplifier (HPA). A first-of-its-kind, frequency-dependent large-signal APD model is presented. This model is used to evaluate different phase relationships between the linear and nonlinear branches, suggesting independent gain and phase expansion characteristics with this topology. This model is used to assess the impact of diode resistance, capacitance, and ideality factors on the APD characteristics. This feature is showcased with two similar GaAs diodes to find the best fit for the considered HPA. The selected diode is characterized and modeled between 1 and 26.5 GHz. A comprehensive APD design and simulation workflow is reported. Before fabrication, the simulated APD is evaluated with the measured HPA to verify linearity improvements. The APD prototype achieves a large-signal bandwidth of 6 GHz with 3 dB gain expansion and 8° phase rotation. This linearizer is demonstrated with a 17–21 GHz GaN HPA with 41 dBm output power and 35% efficiency. Using a wideband 750 MHz signal, this APD improves the noise–power ratio (NPR) by 6.5–8.2 dB over the whole HPA bandwidth. Next, the HPA output power is swept to compare APD vs. power backoff for the same NPR. APD improves the HPA output power by 1–2 W and efficiency by approximately 5–9% at 19 GHz. This efficiency improvement decreases by only 1–2% when including the APD post-amplifier consumption, thus suggesting overall efficiency and output power improvements with APD at K-band frequencies. [ABSTRACT FROM AUTHOR]

Website Fingerprinting (WF) attacks enable a local eavesdropper to use metadata of packet flow, such as size, timing, and direction, to infer the websites a user is visiting. This can damage the user privacy provided by anonymity systems such as Tor. Tor has implemented the WF defense called Circuit Padding Framework, which provides an interface for developers to implement their own defenses. However, these defenses in the framework were overcome by the Deep Fingerprinting (DF) attack. In this paper, we propose a novel defense approach called break burst padding (Break-Pad), which injects a random number of padding packets into an incoming burst once the number of consecutive incoming packets exceeds a set number. We integrated Break-Pad into the existing Circuit Padding Framework. In addition, we have implemented two padding machines named August and October in the new framework and conducted experiments to evaluate these machines. In the open-world setting, our results show that August, with 29% bandwidth overhead, reduces Tik-Tok's TPR by 14.48% and DF's TPR by 22%. October outperforms the best padding machine, RBB. With 36% bandwidth overhead, it drops Tik-Tok's TPR to 74.24% and DF's TPR to 65.36%. In the one-page setting, October further reduces the bandwidth overhead by 11% while achieving similar performance to RBB. In the information leak analysis, for the burst sequence feature of the traffic, October leaks at 2.453 bits, while the best comparable padding machine Interspace leaks at 2.629 bits. [ABSTRACT FROM AUTHOR]

This paper presents a trajectory tracking control scheme for underactuated surface vessels (USVs) with input delay. Firstly, the underactuated surface vessel system is transformed into a fully actuated system using differential flatness theory. To estimate the unknown nonlinear terms introduced in the transformation process, a fuzzy neural network (FNN) is employed. Secondly, to conserve control resources and communication bandwidth, the controller of the system under prescribed performance is designed using the backstepping method. This method updates the controller according to an event-triggered condition that is designed using a Lyapunov function. Finally, theoretical proof and simulation experiments are conducted to demonstrate the convergence and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents a compact V-band low-noise amplifier (LNA) featuring temperature compensation, implemented in a 130 nm SiGe BiCMOS process. A negative temperature coefficient bias circuit generates an adaptive current for temperature compensation, enhancing the LNA's temperature robustness. A T-type inductive network is employed to establish two dominant poles at different frequencies, significantly broadening the amplifier's bandwidth. Over the wide temperature range of −55 °C to 85 °C, the LNA prototype exhibits a gain variation of less than 1.5 dB at test frequencies from 40 GHz to 65 GHz, corresponding to a temperature coefficient of 0.01 dB/°C. At −55 °C, 25 °C, and 85 °C, the measured peak gains are 25.5 dB, 25 dB, and 24.4 dB, respectively, with minimum noise figures (NF) of 3.0 dB, 3.5 dB, and 4.2 dB, and DC power consumptions of 22.3 mW, 27.6 mW, and 34.4 mW. Moreover, the total silicon area of the LNA chip is 0.37 mm2, including all test pads, while the core area is only 0.09 mm2. [ABSTRACT FROM AUTHOR]

A novel bandpass-to-all-stop switchable absorptive filter with an ultra-wideband reflectionless range is proposed in this paper. The bandpass section of the filter consists of a dual-mode resonator and two L-shaped feeding lines. The dual-port reflectionless characteristic is achieved by loading absorption networks at the end of the open stubs of the feeding lines, which are composed of two parallel coupled lines and absorption resistors. The switching of the reflectionless bandpass filter (RBPF) to the all-stop filter (ASF) is realized by controlling the on/off behavior of the PIN diode through the bias voltage. Measurements show that the filter prototype at the center frequency of 2.43 GHz with the 3-dB fractional bandwidth (FBW) is 8.23%. For the RBPF state, the filter has an ultra-wideband reflectionless FBW of 214% and upper stopband rejection better than 33 dB up to 6 GHz. Besides, the rejection is better than 30 dB from 0 to 5.32 GHz in the ASF state. [ABSTRACT FROM AUTHOR]

In this paper, a wideband wide-beam circularly polarized (CP) antenna excited by sequential rotation feeding technology is proposed. The antenna is primarily constituted of a loop radiating element and a reactive impedance structure (RIS) cavity. The loop radiator is stimulated by a curved feeding line through six slots etched on the ground, thereby enabling the antenna to achieve broadband performance. In order to achieve a wide 3-dB axial-ratio beamwidth (ARBW), as well as exhibit less effect on the half-power beamwidth (HPBW), a RIS cavity is introduced beneath the loop radiator. To validate the proposed structure, a prototype was constructed and subjected to a series of tests. The results indicate that the bandwidth of the antenna is 187.5% (0.11 ∼ 3.41 GHz) under a 10-dB return loss. In the frequency band spanning from 1.07 GHz to 2.1 GHz, the AR is less than 3 dB, yielding a bandwidth of 64.98%. Furthermore, at the frequencies of 1.2 GHz, 1.5 GHz, and 1.8 GHz, the proposed antenna demonstrates wide beam characteristics, with the HPBW exceeding 90◦, and the 3-dB ARBW within 162◦ 224◦ . In addition, since no extra feeding network is utilized, the antenna is compact in size. [ABSTRACT FROM AUTHOR]