Line Code Research Articles

A Six-Port Transceiver for Frequency-Division Duplex Systems

In this letter, a six-port transceiver for frequency-division duplex (FDD) systems is proposed and experimentally demonstrated. The proposed transceiver that consists of a single six-port correlator and four Schottky diodes can realize both modulation and demodulation simultaneously at different frequencies. To verify the proposed architecture, the six-port transceiver system prototypes are developed, and modulation and demodulation performances are evaluated by using quadrature amplitude modulation signals at 2.9 and 2.68 GHz, respectively. Moreover, the heterodyne demodulation for a six-port transceiver is proposed to mitigate the interferences from baseband modulation signals. The error vector magnitudes of FDD systems based on the proposed transceiver are found below 2%.

Improving Error Correction Codes for Multiple-Cell Upsets in Space Applications

Currently, faults suffered by SRAM memory systems have increased due to the aggressive CMOS integration density. Thus, the probability of occurrence of single-cell upsets (SCUs) or multiple-cell upsets (MCUs) augments. One of the main causes of MCUs in space applications is cosmic radiation. A common solution is the use of error correction codes (ECCs). Nevertheless, when using ECCs in space applications, they must achieve a good balance between error coverage and redundancy, and their encoding/decoding circuits must be efficient in terms of area, power, and delay. Different codes have been proposed to tolerate MCUs. For instance, Matrix codes use Hamming codes and parity checks in a bi-dimensional layout to correct and detect some patterns of MCUs. Recently presented, column–line–code (CLC) has been designed to tolerate MCUs in space applications. CLC is a modified Matrix code, based on extended Hamming codes and parity checks. Nevertheless, a common property of these codes is the high redundancy introduced. In this paper, we present a series of new low-redundant ECCs able to correct MCUs with reduced area, power, and delay overheads. Also, these new codes maintain, or even improve, memory error coverage with respect to Matrix and CLC codes.

Breeding Miniature <i>Phalaenopsis</i> Cultivar ‘Blanc Rouse’ with White-Colored and Purple-Violet Lip Flowers

The Phalaenopsis cultivar ‘Blanc Rouse’ was bred by the National Institute of Horticultural and Herbal Science (Wanju-gun, Korea) in 2013. The ‘Blanc Rouse’ cultivar was derived from a cross between the miniature cultivar P. ‘KV 600’ and P. ‘Kang 1’ in 2007. In total, 182 seedlings were planted and cultivated in a greenhouse. In 2010, one line was selected on the basis of performance for traits such as flower color, plant height, leaf shape, flower stalk length, and vigorous growth; this line was given the line code “07-003-164.” A second set of analyses was carried out on the selected line with respect to cultivation characteristics and uniformity tests at farms at three different sites in Korea. This hybrid had white-colored petals (WN155A), a purple-violet lip (PVN80B), and small-sized flowers. ‘Blanc Rouse’ produces approximately 39.4 flowers per flower stalk and two flower stalks per plant. The average flower stalk length is 43.5 cm. The general impression of the petals and sepals is that they exhibit a flat shape. It has an early-blooming habit that starts in late November under optimal culture conditions. The leaves of ‘Blanc Rouse’ grow horizontally and are approximately 17.3 cm in length and 6.2 cm in width. This cultivar possesses no genetic variation and is amenable to fast in vitro propagation and easy cultivation management because of its vigorous habit and diseases resistance.

Gate and Bulk-Driven Four-Quadrant CMOS Analog Multiplier

This work presents and validates the design of a four-quadrant analog multiplier based on the bulk-driven technique. Using the source–gate as well as the bulk–source voltages of a PMOS transistor as input ports, the multiplication task can be achieved. The AC signals are injected into the bulk terminals by means of a very-low-frequency programmable high-pass RC network which also serves to set its proper DC operation point. Although two RC networks are required, this multiplication cell is composed of only seven PMOS transistors and two coupling capacitors which makes it a very compact circuit. Furthermore, no preprocessed signals like the sum of $$\pm \,v_x \pm \,v_y$$ are required at the input ports. The implemented circuit shows a bandwidth of 50 MHz for an output capacitance of 40 pF and a THD lower than 1 $$\%$$ for gate/bulk input amplitudes below 0.2 Vp. The power consumption of the multiplication core is 660 $$\upmu $$ W and 2.6 mW including output buffers. In order to simulate and fabricate this circuit, an ON Semi 0.50 $$\upmu $$ m CMOS standard technology is used, showing a silicon area consumption of $$280\,\upmu \hbox {m} \times 400\,\upmu $$ m including output buffers. The proposed multiplier is suitable for biomedical, AM modulation, base-band modulation and analog computation.

Designing prefix code to save energy for wirelessly powered wireless sensor networks

In the Internet of Things, wireless sensor networks (WSNs) are widely deployed. In recent years, wirelessly powered WSNs or battery-free WSNs (BF-WSNs), in which the nodes harvest energy from radio signals in the environment, have been emerging to support sustainable operation for WSNs. It is significant to design an energy-efficient data delivery scheme for the BF-WSNs. In this study, the authors propose the prefix code based scheme (PCBS) to save energy in data delivery by making use of the energy consumption disparity (ECD) between transmitting/receiving bit 0 and bit 1 in the existing non-modulation baseband transmission or carrier-modulation based passband transmission. The authors formulate an optimisation problem and use genetic algorithm to find its solution so that the energy-efficient prefix codebook is obtained. The codebook dilutes the ECD by containing the energy-consuming bit as few as possible, and the PCBS maps each m-bit data block into a prefix codeword in the codebook to conduct energy-efficient transmission at the transmitter and vice versa at the receiver. Both the experiments on wireless identification sensing platform and the simulations demonstrate that the proposed PCBS outperforms the existing schemes in terms of energy saving.

Vector multi-rogue waves for the three-coupled fourth-order nonlinear Schrödinger equations in an alpha helical protein

In this paper, we investigate the vector multi-rogue waves for the three-coupled fourth-order nonlinear Schrödinger equations, which describe the dynamics of an alpha helical protein with the nearest and next-nearest neighbor interactions and interspine coupling. Via the Darboux-dressing transformation, the vector multi-rogue-wave solutions are derived. Based on such solutions, we present the single vector rogue wave, vector rogue wave pair and triple vector rogue wave graphically. We show that a four-petaled rogue wave with two humps and two valleys appears in two components, while the other component has an eye-shaped rogue wave. Existing time of the rogue wave decreases with the strength of higher-order linear and nonlinear effects in the alpha helical protein. We also obtain the separated and interacting vector rogue wave pairs, as well as the triple vector rogue waves. Moreover, we verify the baseband modulation instability through the linear stability analysis.

Mitigation of RB noise in bidirectional fiber transmission systems based on different OFDM SSB techniques

The interferometric beat noise due to the reflections (RE) from passive devices and the Rayleigh backscattering (RB) in wavelength reuse bidirectional fiber optic transmission systems leads to degradation of the system if not employed with a suitable RB mitigation technique. These noises can be reduced by implementation of the modulation schemes which reduce the spectral overlap between the data signal and RB-RE signals. In this paper, a bidirectional architecture to reduce RB-RE noise in wavelength reused bidirectional Radio over Fiber (RoF) is proposed. Optical Orthogonal Frequency Division Multiplexing (OFDM) Single Sideband (SSB) techniques are used for upstream and downstream transmission. Two SSB millimeter wave signals viz. conventional SSB and modified SSB are generated by the MZM employing a hybrid coupler to generate different phase shifts (90° & 120°) of the RF signal applied to its electrodes. In our architecture, the spectral overlap between the data signal and RB-RE signals is reduced by transmitting the downstream and upstream signals on the higher and lower first order optical sidebands of the SSB signal respectively. A mathematical model is developed to analyze the transmission performance of the two SSB techniques based on RB-RE interferences. An m-QAM optical OFDM baseband modulation scheme is used to transmit 10 Gbps data over 75 km fiber using the two SSB modulation schemes. Our results show that the modified SSB eliminates 2nd order RB-RE harmonics reduces RB-RE crosstalk against the conventional SSB.

Maintaining Architecture-Implementation Conformance to Support Architecture Centrality

Architecture-centric development addresses the increasing complexity and variability of software systems by focusing on architectural models, which are generally easier to understand and manipulate than source code. It requires a mechanism that can maintain architecture-implementation conformance during architectural development and evolution. The challenge is twofold. There is an abstraction gap between software architecture and implementation, and both may evolve. Existing approaches are deficient in support for both change mapping and product line architecture. This article presents a novel approach named 1.x-way mapping and its extension, 1.x-line mapping to support architecture-implementation mapping in single system development and in product line development, respectively. They specifically address mapping architecture changes to code, maintaining variability conformance between product line architecture and code, and tracing architectural implementation. We built software tools named xMapper and xLineMapper to realize the two approaches, and conducted case studies with two existing open-source systems to evaluate the approaches. The result shows that our approaches are applicable to the implementation of a real software system and are capable of maintaining architecture-implementation conformance during system evolution.

Research and Analysis of Digital Baseband Transmission System Based on MATLAB

This paper mainly studies the basic concept of baseband transmission of digital signal and the transmission processof digital signal baseband transmission and how to design digital baseband transmission system with MATLABsoftware simulation. This paper fi rst introduces the theoretical basis of this subject, including digital communication,the composition of digital baseband transmission system and digital baseband signal transmission process. Then thepaper introduced the characteristics of digital baseband transmission system, including digital PAM signal powerdensity and common line pattern, and by comparing choosing the fi nal bipolar zero return code. Then we introducedthe MATLAB simulation software. The conditions of the best reception of the digital baseband signal are describedand how the waveform of the baseband signal is observed by an oscilloscope. Finally, according to the basic stepsof simulation process, the simulation process of digital baseband transmission system is realized by MATLABsimulation tool, and the system is analyzed.

A Performance Enhancement and High Speed Spectrum Sliced Free Space Optical System

A cost effective Kerr nonlinearity based spectrum sliced (SS) WDM free space optical communication system is demonstrated under different weather instabilities. The investigated supercontinuum spectrum sliced WDM FSO system is evaluated at 2.5 Gbps up to 5 km of link distance. A highly nonlinear fiber is a channel for the generation of high power broad spectrum for spectrum slicing. A dense SS-WDM is investigated at 75 GHz channel spacing among 4 channels to make system bandwidth efficient. The system is investigated for different line coding (return to zero, non return to zero) and advanced modulation format such as compressed spectrum return to zero. A major degrading factor in free space communication i.e. beam divergence is also analyzed for investigated work. Antenna diameters of receiver and transmitter play a vital role in FSO, thus various diameters performances are also studied. The approach is to cater the high-speed data demands and thus system deliberated and demonstrated from 2.5 to 10 Gbps. To strengthen the signal in this FSO system, three optical amplifiers are scrutinized such as erbium doped fiber amplifier (EDFA), semiconductor optical amplifier (SOA) and Raman amplifier in terms of bit error rate and quality factor. Results revealed that EDFA is the best amplifier in investigated SS-WDM-FSO system.

Encoding Scheme to Reduce Energy Consumption of Delivering Data in Radio Frequency Powered Battery-Free Wireless Sensor Networks

Wireless sensor networks (WSNs) have been widely deployed in intelligent transportation systems. Battery-free WSN (BF-WSN) scavenges energy from the environment. In the BF-WSN, whose nodes harvest radio frequency (RF) energy, delivering data with low energy consumption is important for the BF-WSN nodes to have a longer runtime. Some existing baseband encoding or carrier-modulation schemes exhibit the energy consumption disparity (ECD) between transmitting bit 0 and bit 1. An example is FM0 (bi-phase space) baseband encoding, which is widely applied in the backscattering communications in radio frequency identification systems and wireless identification sensing platform. With FM0, transmitting bit 0 consumes much greater energy than bit 1. To achieve energy-saving in delivering data with the ECD, we, in this paper, formulate the optimization problem (OP) that maximizes percentage of energy saving. The solution of the OP leads to the optimal energy-efficient codebook. Based on the derived codebook, we present the energy-efficient data delivery scheme (EEDDS), with which the sender transmits the codewords in the codebook and the receiver recovers the corresponding original data blocks using the codebook. Simulation results show that the proposed EEDDS outperforms the traditional data delivery scheme in terms of energy consumption in the case when the applied baseband encoding or carrier-modulation schemes occupy the ECD.

Performance Characterization of Spatial Diversity Based Optical Wireless Communication over Atmospheric Turbulence Channels

Optical wireless communication is regarded as the next-generation high-speed technology. It has demonstrated its capability to deliver data faster than any other state-of-the-art wireless communication technique. This technology has drawn attention as a means of implementing reliable high capacity outdoor systems that cannot be implemented by conventional fiber optics. It has emerged recently as an efficient solution to match the larger bandwidth and high data rates requirement of the upcoming wireless communication systems. However, although FSO (free space optics) system has many appealing features, it has rather disappointing performance for long links due to the degrading effects of atmospheric turbulence-induced fading. In the presence of such type of performance impairments, the received signal exhibits random intensity fluctuations, which increase the BER (bit error-rate), where the severe weather conditions can have a detrimental impact on the performance, which may result in an inadequate availability. The MIMO wireless optical procedure, in which the spatial dimensions are used to improve the reliability and spectral efficiency of point-to-point links, provides a promising approach to mitigate turbulence effects due to its powerful performance enhancing capabilities. In this paper, we investigate a terrestrial atmospheric FSO communication system operating under the influence of strong atmospheric turbulences. Additionally, the MIMO technique with equal gain combining (EGC) is used in this work to enhance the data rate of the proposed system. Atmospheric turbulence impacts are modeled as a lognormal channel with due regard for geometric losses. With the use of NRZ line coding, an FSO highly sensitive receiver using either avalanche photodetector (APD) or PIN is designed and simulated for best system performance. The preference is achieved by using Bessel and Gaussian filters. It has been found that APD receiver using Gaussian filter is suitable for long-range links with APD gain value of 3. Also, the selection of APD gain is critical to the system performance. In addition, the optimal value of APD gain required for best system performance decreases as the size of the MIMO technique increases. The achievable performance improvements including received power levels, BER and Q-factor are also discussed. The results show that the system with optical amplifier at the transmitter gives an optimum performance. In addition the system performance is enhanced in most weather conditions by using an amplified 2×2 MIMO-FSO system with booster amplifier.

GAME: GAlaxy Machine learning for Emission lines

We present an updated, optimized version of GAME (GAlaxy Machine learning for Emission lines), a code designed to infer key interstellar medium physical properties from emission line intensities of UV/optical/far infrared galaxy spectra. The improvements concern: (a) an enlarged spectral library including Pop III stars; (b) the inclusion of spectral noise in the training procedure, and (c) an accurate evaluation of uncertainties. We extensively validate the optimized code and compare its performance against empirical methods and other available emission line codes (PYQZ and HII-CHI-MISTRY) on a sample of 62 SDSS stacked galaxy spectra and 75 observed HII regions. Very good agreement is found for metallicity. However, ionization parameters derived by GAME tend to be higher. We show that this is due to the use of too limited libraries in the other codes. The main advantages of GAME are the simultaneous use of all the measured spectral lines, and the extremely short computational times. We finally discuss the code potential and limitations.

An Experimental Study of a Micro-Projection Enabled Optical Terminal for Short-Range Bidirectional Multi-Wavelength Visible Light Communications.

A micro-projection enabled short-range communication (SRC) approach using red-, green- and blue-based light-emitting diodes (RGB-LEDs) has experimentally demonstrated recently that micro-projection and high-speed data transmission can be performed simultaneously. In this research, a reconfigurable design of a polarization modulated image system based on the use of a Liquid Crystal on Silicon based Spatial Light Modulator (LCoS-based SLM) serving as a portable optical terminal capable of micro-projection and bidirectional multi-wavelength communications is proposed and experimentally demonstrated. For the proof of concept, the system performance was evaluated through a bidirectional communication link at a transmission distance over 0.65 m. In order to make the proposed communication system architecture compatible with the data modulation format of future possible wireless communication system, baseband modulation scheme, i.e., Non-Return-to-Zero On-Off-Keying (NRZ_OOK), M-ary Phase Shift Keying (M-PSK) and M-ary Quadrature Amplitude Modulation (M-QAM) were used to investigate the system transmission performance. The experimental results shown that an acceptable BER (satisfying the limitation of Forward Error Correction, FEC standard) and crosstalk can all be achieved in the bidirectional multi-wavelength communication scenario.

An Anti-Collision Algorithm for RFID Based on an Array and Encoding Scheme

In order to solve the problem of tag collision in Radio Frequency Identification (RFID) system, the paper proposes a Multi-Bit Identification Collision Tree (MICT) algorithm based on a collision tree. The algorithm uses an array scheme to mark the collision bits in the identification process, and determines the collision information according to the first few bits of the tag, which can effectively reduce the number of recognitions and the amount of communication data. The testing results show that the proposed algorithm reduces the time complexity by about 38% and the communication complexity by about 27% compared to existing collision-tree-based algorithms. Through theoretical analysis and experimental evaluation, the MICT algorithm has obvious advantages in terms of time and communication complexity compared to the other typical algorithms. The algorithm can be applied to the field of RFID-related systems to significantly improve the system efficiency.

Polarization of K-shell Dielectronic Recombination Satellite Lines of Fe xix–xxv and Its Application for Diagnostics of Anisotropies of Hot Plasmas

We present a systematic measurement of the X-ray emission asymmetries in the K-shell dielectronic, trielectronic, and quadruelectronic recombination of free electrons into highly charged ions. Iron ions in He-like through O-like charge states were produced in an electron beam ion trap, and the electron-ion collision energy was scanned over the recombination resonances. Two identical X-ray detectors mounted head-on and side-on with respect to the electron beam propagation recorded X-rays emitted in the decay of resonantly populated states. The degrees of linear polarization of X-rays inferred from observed emission asymmetries benchmark distorted-wave predictions of the Flexible Atomic Code (FAC) for several dielectronic recombination satellite lines. The present method also demonstrates its applicability for diagnostics of energy and direction of electron beams inside hot anisotropic plasmas. Both experimental and theoretical data can be used for modeling of hot astrophysical and fusion plasmas.

Extension of NVNA Baseband Measurement for PA Characterization Under Complex Modulation

We investigated the measurement techniques of the nonlinear vector network analyzer (NVNA) test bench, to fully characterize the nonlinear behavior of radio frequency (RF) power amplifiers (PAs) driven by complex modulated signals. In order to extend the baseband measurements, two kinds of NVNA phase reference approaches are developed as alternative solutions, so that the baseband phase measurements can be achieved with those of modulated components at multiharmonic RF bands. In the first approach, a modulated baseband signal is combined with another modulated RF one to become the desired NVNA phase reference. While as an alternative solution, the second phase reference design is based on a “stepped” multisine, which is stepped through the baseband and each harmonic following the NVNA swept measurements, to achieve stable phase measurements. To validate these proposed NVNA test bench designs, an RF PA, driven by a large-signal long-term evolution-like multisine, was tested and compared with digital real-time oscilloscope measurements.

A New Quantum Gray-Scale Image Encoding Scheme**Supported by Kermanshah Branch, Islamic Azad University, Kermanshah, IRAN

In this paper, a new quantum images encoding scheme is proposed. The proposed scheme mainly consists of four different encoding algorithms. The idea behind of the scheme is a binary key generated randomly for each pixel of the original image. Afterwards, the employed encoding algorithm is selected corresponding to the qubit pair of the generated randomized binary key. The security analysis of the proposed scheme proved its enhancement through both randomization of the generated binary image key and altering the gray-scale value of the image pixels using the qubits of randomized binary key. The simulation of the proposed scheme assures that the final encoded image could not be recognized visually. Moreover, the histogram diagram of encoded image is flatter than the original one. The Shannon entropies of the final encoded images are significantly higher than the original one, which indicates that the attacker can not gain any information about the encoded images.

Design of Low Power VLSI Architecture of Line Coding Schemes

Line coding is used to tune the wave form based on the properties of the physical channel. The wave form is tuned in voltage or current or photon levels for the proper digital data transport. Bi-Phase Mark Coding (BMC), Bi-Phase Space Coding (BPSC) and Phase Coding (PC) are used as Line coding techniques. Most of the existing systems discuss about any one of the coding techniques among BPSC and PC. Limited number of systems discusses about BPSC and PC generation and degeneration operations together. The first objective of the proposed work is to design BMC, BPSC and PC techniques Generation and Degeneration operation in a single system. The second objective is to reduce the area and power consumption by modifying the number of MOS devices used for the system design and by adjusting the width of the MOS devices. The system is designed using Cadence® Virtuoso Schematic Editor at 180 nm technology. Simulation is done using Cadence® Virtuoso ADE and the Layout is designed using Cadence® Virtuoso Layout Suite XL. The proposed system requires 59 transistors and occupies 1632.88 µm2. Required power can be reduced up to 33% by using any one of the suitable coding among BMC, BPSC and PC based on the properties of the input data signal. If the input data is having equal possibility of high and low level signals, PC technique will be suitable for power reduction. If the high level beats the low level, BPSC technique will be suitable. If the low level beats the high level, BMC technique will be suitable.

Beating the classical limits of information transmission using a quantum decoder

Encoding schemes and error-correcting codes are widely used in information technology to improve the reliability of data transmission over real-world communication channels. Quantum information protocols can further enhance the performance in data transmission by encoding a message in quantum states, however, most proposals to date have focused on the regime of a large number of uses of the noisy channel, which is unfeasible with current quantum technology. We experimentally demonstrate quantum enhanced communication over an amplitude damping noisy channel with only two uses of the channel per bit and a single entangling gate at the decoder. By simulating the channel using a photonic interferometric setup, we experimentally increase the reliability of transmitting a data bit by greater than 20% for a certain damping range over classically sending the message twice. We show how our methodology can be extended to larger systems by simulating the transmission of a single bit with up to eight uses of the channel and a two-bit message with three uses of the channel, predicting a quantum enhancement in all cases.