High-speed Data Communication Research Articles

0.5-Gb/s OFDM-Based Laser Data and Power Transfer Using a GaAs Photovoltaic Cell

In this letter, we demonstrate for the first time the additional capability of high-speed data communication for single-junction photovoltaic (PV) cells. A record 3-dB bandwidth of 24.5 MHz is reported for a gallium arsenide (GaAs) PV cell. The PV cell is shown to achieve a power efficiency of at least 42% when irradiance of 0.46 W/cm2 is received from 847-nm vertical-cavity surface-emitted laser. Optimized bit-and-power-loaded optical orthogonal frequency-division multiplexing (OFDM) is applied to use the communication bandwidth most efficiently. With this, a data rate of 0.5 Gb/s is achieved for a 2-m OFDM-based laser link. To the best of our knowledge, the reported data rates achieved with a GaAs PV cell as the detector are the highest for simultaneous optical wireless information and power transfer.

New control systems at KSTAR compatible with ITER standard technologies

Through the lessons learned during the ITER control, data access and communication (CODAC) tasks and the interaction with various domestic and overseas communities, the KSTAR control system is being improved with new functions. We have adopted ITER synchronous data bus network (SDN) and time communication network (TCN) to increase the flexibility of control system design and improve system performance. Absolute time-based discharge operations and high-speed data communication interfaces are standardized as KSTAR standard software components. We used the reconfigurable I/O (RIO) library provided by CODAC for the renovation of a fast interlock system, and effectively implemented a real-time core structure through ITER for the next generation real-time control systems. A new hardware platform standard has been adopted for system standardization and convenience of maintenance international collaboration.

Dynamic parameter estimation of Analog to Digital Converter with multipoint Interpolation technique

Objectives: The objective of this paper is to estimate the dynamic parameters of Analog to Digital Converter (ADC) with multi frequency sine signal as stimuli. Methods/Statistical Analysis: Traditionally the characteristics of a signal are estimated with its spectrum using Fast Fourier Transform (FFT) algorithm. Interpolated FFT technique gives more accurate results compared to the FFT technique. The signal is weighted with rectangular and Hanning window before the Discrete Fourier Transform (DFT) is calculated, frequency and magnitude of various components of input stimulus are estimated with this technique. Weighted signal is applied to ADC under test and the frequency spectrum of digital output is obtained. Findings: This technique is used to determine the frequency dependent parameters of ADC. The analytical formula for amplitude, frequency and phase estimation is simple to implement. The expression for the accurate estimation of the fractional part between the two largest spectrums of the recorded cycles by IP DFT method is presented. Sampled input signal is weighted with rectangular and tapered window and averaged. A reduction in noise level can be observed in the spectrum. The obtained values of frequency, amplitude and phase which are more accurate as presented in literature. Comparative values of ideal and real ADC dynamic parameters are presented here. The research work carried can contribute significantly to ADC design and testing with multi frequency input signals. The novelty of this approach is that the accurate results for dynamic parameters of ADC can be characterized for a particular bandwidth in a single run. Application/Improvements: An ADC is a vital component in high-speed data communications video and radar systems. The overall accuracy of the system is dependent on the accuracy of the ADC. For such systems, dynamic testing of the device using standard signal is not useful. Therefore dynamic testing of ADC under application conditions is needed. The techniques discussed in the paper are very much useful in testing high-speed ADCs by the manufacturer as well as a circuit designer. Keywords: Analog to Digital Converter, Dynamic Parameters, Multi Frequency Signal, Multipoint Interpolation

A Low-Cost Comparator-Based Method for Accurate Decomposition of Deterministic Jitter in High-Speed Links

Jitter decomposition is a key tool to identify root causes of jitters in a high-speed digital communication system. It is a huge challenge in balancing the test cost and precision for conventional decomposition methods implemented in instruments where the time interval error (TIE) data are necessary. In this paper, we propose a deterministic jitter decomposition method using Boolean output from a network of simple low-cost comparators to identify the deviation of current sampling position from the ideal sampling position instead of TIE data. The new method simultaneously separates intersymbol interference (ISI), periodic jitter (PJ), and duty cycle distortion (DCD). Simulation and measurement results demonstrate that the proposed method can estimate the ISI, PJ, and DCD with sufficient accuracy using significantly fewer data samples than the state-of-the-art instrument test, and thus, reduce test cost greatly. Furthermore, the comparators have extremely relaxed design requirements, offering potential for possible on-chip implementation for built-in self-test or background test.

Performance Analysis of OFDMA and SC-FDMA

The main challenge in any high-speed digital communication system is how to maximize the data rate with minimizing the bit error rate. Several techniques have been developed to achieve this point. Some of these techniques are orthogonal frequency division multiplexing (OFDM), single-carrier frequency domain equalization (SC-FDE), orthogonal frequency division multiple access (OFDMA), and single-carrier frequency division multiple access (SC-FDMA). These four techniques are described briefly in this paper. Also, the paper measures the performances of OFDMA and SC-FDMA systems over international telecommunication union (ITU) vehicular-A channel using minimum mean square error (MMSE) equalization. Simulation results show that the performances with interleaved mapping outperform that with localized mapping. Also, the performances with quadrature phase shift keying(QPSK) are better than that with 16-ary quadrature amplitude modulation (16QAM). In addition, the performance of SC-FDMA is better than that of OFDMA, when QPSK is used, but the latter is little bit better than that of SC-FDMA when 16QAM is used

Performance analysis of OFDMA and SC-FDMA

The main challenge in any high-speed digital communication system is how to maximize the data rate with minimizing the bit error rate. Several techniques have been developed to achieve this point. Some of these techniques are orthogonal frequency division multiplexing (OFDM), single-carrier frequency domain equalization (SC-FDE), orthogonal frequency division multiple access (OFDMA), and single-carrier frequency division multiple access (SC-FDMA). These four techniques are described briefly in this paper. Also, the paper measures the performances of OFDMA and SC-FDMA systems over international telecommunication union (ITU) vehicular-A channel using minimum mean square error (MMSE) equalization. Simulation results show that the performances with interleaved mapping outperform that with localized mapping. Also, the performances with quadrature phase shift keying (QPSK) are better than that with 16-ary quadrature amplitude modulation (16QAM). In addition, the performance of SC-FDMA is better than that of OFDMA, when QPSK is used, but the latter is little bit better than that of SC-FDMA when 16QAM is used.

Realization of all-optical NAND and NOR logic functions with photonic crystal based NOT, OR and AND gates using De Morgan’s theorem

In this article, we propose the realization of photonic crystal based all-optical universal logic gates, NAND and NOR with basic logic gates viz. NOT, AND and OR in two level logic using De Morgan’s theorem. As per the theorem, NAND or NOR gate can be designed with two NOT gates in first level, cascaded to a second level OR gate or AND gate, respectively. Initially, the basic logic gates are designed and optimized such that their implementation in the design of NAND and NOR gates cannot degrade the threshold value of logic levels. Length of the input waveguides in each design is kept common so as to have a change in the interference of the input signals with a phase difference of 0° and 180°. The proposed basic logic gates are resulted with a contrast ratio of 11.04, 8.24, and 5.18 dB, respectively. While the calculated values of contrast ratio of NAND and NOR gates are 5.81 and 4.02 dB, respectively. Moreover, the bit rate of the proposed designs is above 7.485 Tbps which shows their inevitable usage in high speed data communication networking.

A potent approach for the development of FPGA based DAQ system for HEP experiments

With ever increasing particle beam energies and interaction rates in modern High Energy Physics (HEP) experiments in the present and future accelerator facilities, there has always been the demand for robust Data Acquisition (DAQ) schemes which perform in the harsh radiation environment and handle high data volume. The scheme is required to be flexible enough to adapt to the demands of future detector and electronics upgrades, and at the same time keeping the cost factor in mind. To address these challenges, in the present work, we discuss an efficient DAQ scheme for error resilient, high speed data communication on commercially available state-of-the-art FPGA with optical links. The scheme utilises GigaBit Transceiver (GBT) protocol to establish radiation tolerant communication link between on-detector front-end electronics situated in harsh radiation environment to the back-end Data Processing Unit (DPU) placed in a low radiation zone. The acquired data are reconstructed in DPU which reduces the data volume significantly, and then transmitted to the computing farms through high speed optical links using 10 Gigabit Ethernet (10GbE). In this study, we focus on implementation and testing of GBT protocol and 10GbE links on an Intel FPGA. Results of the measurements of resource utilisation, critical path delays, signal integrity, eye diagram and Bit Error Rate (BER) are presented, which are the indicators for efficient system performance.

Resonance-free optical response of a vertical cavity transistor laser

Optical resonance in a semiconductor laser is a major limitation in high speed data communications, resulting in bit error rate degradation and requiring additional power consuming error-correction circuits to counter these effects. In this work, we report the microwave bandwidth measurement of a vertical cavity transistor laser with an oxide-confined aperture of 4.7 × 5.4 μm2 and demonstrate a 3 dB bandwidth of 11 GHz resonance-free optical response via base-current or collector-voltage modulation. The emission spectra exhibit single-mode operation around 970 nm with a narrow linewidth of Δλ ∼ 0.23 Å (cavity Q of 42 216). The resonance-free optical response is explained by the absence of carrier “accumulating” due to the fast base electron-hole recombination lifetimes and a gradient in the minority carrier charge in the transistor active mode.

Pea-Sized mmW Transceivers: QFN-?Based Packaging Concepts for Millimeter-Wave Transceivers

Enormous technological progress accomplished over the last several decades has facilitated the use of millimeter-wave (mmW) frequencies for mass-produced products such as automotive radars, industrial sensors, highspeed data communication links, and medical devices. The main enablers are new semiconductor technologies, with constantly improving cut-off frequencies reaching several hundred gigahertz. However, the dominant limiting factor for the mass production of low-cost mmW systems above 100 GHz is that suitable packaging technologies are not yet available. Still, a dramatic increase in research and development is taking place in the area of mmW packaging. The goal of this article is to provide a short overview of the topic and then present one particular approach in detail: the idea of integrating a complete mmW front end, including the antenna, into one small solderable surfacemount device (SMD).

Nanopatterned luminescent concentrators for visible light communications

Visible light communication (VLC) is a promising candidate for high-speed wireless communication with numerous unlicensed spectrum. To achieve high-speed data communication, it requires intense light signals concentrated on a tiny fast photodiode. The common way of using focusing optics reduces the field of view (FoV) of the photodiode due to the conservation of étendue. Luminescent solar concentrators (LSC) provide a solution to enhance the signals without affecting the FoV. In this paper we demonstrate nanopatterned LSCs fabricated on flexible plastics that achieve a doubling of optical gain compared to its traditional rectangular counterparts. These LSCs can free VLC detectors from complex active pointing and tracking systems, making them compatible with smart mobile terminals in a simple fashion.

Low-Power Wideband Analog Channelization Filter Bank Using Passive Polyphase-FFT Techniques

Polyphase-FFT (P-FFT) techniques allow for low power implementations of high performance multi-channel filter banks by utilizing computation sharing like a standard fast Fourier transform (FFT). Additionally, it enables a longer “effective window length” than is possible in a standard FFT. This characteristic breaks the trade-off between the main-lobe width and the side-lobe amplitudes in normal finite impulse response filters. Thus, P-FFT techniques have been employed for the channelization of wideband input signals in high speed digital communication receivers. In this paper, we present a prototype analog P-FFT based filter bank in discrete time that is used to channelize wideband input signals so as to reduce the speed and dynamic range requirement of the ADCs. The four-channel I/Q prototype is implemented using TSMC’s 65 nm GP technology. Based on passive switches, the design operates at high speed, consumes low power, and offers high linearity performance. The measured transfer function shows >38 dB side-lobe suppression at 1 GS/s operation. The average measured IIP3 is +25 dBm differential power and the total integrated output noise is 208 $\mu V_{\mathrm{ rms}}$ . The total power consumption for the P-FFT filter bank (eight-channels total) is 34.6 mW (34.6 pJ/conv).

Tailoring optical orbital angular momentum spectrum with spiral complex field modulation.

We report the generation of prescribed optical orbital angular momentum (OAM) spectrum with spiral complex field modulation. Both symmetric and asymmetric OAM spectrums are generated with a vector beam generator and measured with a hybrid conformal mapper. Three methods for OAM spectrum generation ranging from the pure spiral phase modulation, the spiral amplitude and phase modulation, to the spiral phase and polarization modulation are demonstrated. The OAM spectrum generation with spiral complex field modulation may find applications in optical trapping and high-speed data communication.

QoE-Driven Cross-Layer Downlink Scheduling for Heterogeneous Traffics Over 4G Networks

With the soaring demands for high speed data communication, as well as transmission of various types of services with different requirements over cellular networks, having a decent radio resource management is considered vital in Long Term Evolution (LTE) system. In particular, satisfying the quality of service (QoS) requirements of different applications is one of the key challenges of radio resource management that needs to be dealt by the LTE system. In this paper, we propose a cross-layer design scheme that jointly optimizes three different layers of wireless protocol stack, namely application, Medium Access Control, and physical layer. The cross-layer optimization framework provides efficient allocation of wireless resources across different types of applications (i.e., real-time and non real-time) run by different users to maximize network resource utilization and user-perceived QoS, or also known as Quality of Experience (QoE). Here, Mean Opinion Score is used as a unified QoE metric that indicates the user-perceived quality for real-time or multimedia services notably video applications. Along with multimedia services, the proposed framework also takes care of non-real-time traffic by ensuring certain level of fairness. Our simulation, applied to scenarios where users simultaneously run different types of applications, confirms that the proposed QoE-oriented cross-layer framework leads to significant improvement in terms of maximizing user-perceived quality as well as maintaining fairness among users.

Multi-level quantization and blind equalization based direct transmission method of digital baseband signal

The direct transmission of digital baseband signals has practical significance in the field of Ethernet terminal connection, high-speed digital communication, data transmission of various types of information peripherals. The signal amplitude gradually decays while the transmission distance increases. Also the attenuation is proportional to the signal frequency, resulting in signal distortion and receiving error. It is a common method for digital baseband signal transmission to use pre-emphasis chip and equalizer chip to improve the transmission quality with a wide range of mature applications. This paper describes a new type of digital signal transmission method, as the receiver using analog-to-digital converter, instead of equalizer chip, to achieve the multi-level quantization of receiving time-domain data waveform. The waveform of the transmitted digital high and low level signal is sampled into multi-bit values. Then, the paper realizes adaptive frequency domain equalization based on soft threshold and makes use of multi-level quantization soft information for error correction. Error correcting code is mainly used to correct the error caused by the channel bandwidth limit, external noise or interference in the process of data transmission, so as to improve the stability and reliability of the transmission. The paper uses the two-stage error correcting codec system based on both Turbo and BCH coding, to achieve the high performance of Turbo code, and good characters of respond time and complexity. The transmitter outputs 12.5 MHz pseudo-random sequence through a 199.93 meter unshielded balanced twisted pair transmission medium. And the receiver circuit using a 62.5MSPS analog-to-digital converter over-samples the waveform to 8-level quantity. The output error of a 65536 bit pseudo-random sequence is less than 8 bits, and the error correction can be further improved by 8b-10b codec. Compared with the traditional pre-emphasis and balanced interface ICs connection, the method described in this article has the advantages of longer transmission distance, better flexibility and wider scope of use.

Wind Driven Optimization Technique for Equalization of Non-Minimum Phase Channel

Background/Objectives: We propose Wind Driven Optimization (WDO) algorithm as a novel technique to equalize the effects of non-minimum phase FIR channel in band limited high speed digital communication receivers. Methods/Statistical Analysis: This work aims at investigating the performance of WDO based channel equalizer in combating linear and nonlinear distortions caused due to Inter-Symbol Interference (ISI), Additive White Gaussian Noise (AWGN), multipath propagation etc. Findings: The non minimum phase channel is also equalized using Particle Swarm Optimization (PSO) and Genetic Algorithm (GA), which is similar class of populations based iterative soft computing optimization algorithms aiming to achieve global solution. Application/Improvements: In the end, performance comparison is done and simulation results illustrate that WDO algorithm improves the reliability of channels equalization and is more robust to various channel conditions.

Modified Wideband Bowtie Antenna for WLAN and High Speed Data Communication Applications

A simple method is proposed for enhancement in bandwidth and gain of the self complementary Bowtie antenna. This method overcomes the use of complicated fractal structures to increase the bandwidth and gain of the Bowtie antenna. Using this simple method, by making variation of the single dimension of the antenna structure, the bandwidth is improved by 21% and return loss S11 is also improved of whole of the band of interest. The major importance of this simple technique is that it can be applied to any rectangular microstrip antenna. The resonance frequencies and bandwidths can also be steered within the limited ranges also.

Frequency synthesis of forced opto-electronic oscillators at the X-band

Ultra-low phase noise performance is required for frequency agile local oscillators, which are the core for high resolution imagers, spectrum analyzers, and high speed data communications. A forced opto-electronic oscillator (OEO) benefits from frequency stabilization techniques for realizing a clean and low phase noise source at microwave and millimeter wave frequencies. Forced oscillation techniques of self-injection locking and self-phase lock loop are combined to provide an ultra-low oscillator phase noise both close-in and far-away from the carrier frequency, while a tunable yttrium iron garnet microwave filter combined with a wavelength tuned transversal filter are employed to implement both coarse and fine frequency tuning for a tunable X-band OEO. A phase noise of −137 dBc/Hz at an offset frequency of 10 kHz is achieved covering the frequencies of 9 to 11 GHz with a fine frequency tuning resolution of 44 Hz/pm and coarse tuning of 25 MHz/mA. Moreover, the long term stability of the output signal is tested, and a maximum frequency drift of 2 kHz is measured within 60 min for the X-band synthesizer.

Plasmonic Organic Hybrid Modulators—Scaling Highest Speed Photonics to the Microscale

Complementing plasmonic slot waveguides with highly nonlinear organic materials has rendered a new generation of ultracompact active nanophotonic components that are redefining the state of the art. In this paper, we review the fundamentals of this so-called plasmonic- organic-hybrid (POH) platform. Starting from simple phase shifters to the most compact IQ modulators, we introduce key devices of high-speed data communications. For instance, all-plasmonic Mach-Zehnder modulators (MZMs) are reviewed and long-term prospects are discussed. This kind of modulator already features unique properties such as a small footprint (<; 20 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), a large electro-optic bandwidth (> 110 GHz), a small energy consumption (~25 fJ/b), a large extinction ratio (> 25 dB) in combination with a record small voltage-length product of 40 Vμm. Finally, as an example for seamless integration we introduce novel plasmonic IQ modulators. With such modulators we show the generation of advanced modulation formats (QPSK, 16-QAM) on footprints as small as 10 μm × 75 μm. This demonstration ultimately shows how plasmonics can be used to control both phase and amplitude of an optical carrier on the microscale with reasonably low losses.

Study of Slotted Array Waveguide with High Peak Gain Antenna for Data Communication

Objectives: This article manifests a study of high peak gain of a slotted array waveguide antenna. At first, two similar slot lengths 2-elements shunt slotted array antenna structures (i.e. Case-1) and two dissimilar slot lengths 2-elements shunt slotted array antenna structures (i.e. Case-2) are designed one by one. Methods/Statistical Analysis: The Multiple Cavity Modeling Technique (MCMT) has been applied in both cases of structural antennas. The scattering parameters (i.e. |S11| and |S21|) data have been computed for both cases of 2-element shunt slotted array antenna. The MCMT |S11| and |S21| data graphs have been compared with Ansoft High Frequency Structure Simulator (HFSS) simulated data graphs. Comparison results signify that a slight difference between computed and simulated data. Findings: Subsequently, the HFSS simulated gains total of the both cases of design structures antenna are obtained. The outcome found in 2-element shunt slotted array with similar slot length gains higher total rather than dissimilar slot length 2-element shunt slotted array antenna. In order to achieve further increases in gain a 2-elements lotted array antenna up to optimal point was extended up to seven slots. Analysis was done to compare the results with theoretical and simulated HFSS results. Application /Improvement: The antenna finds its application in high speed data communication system in the area of aircraft.