Vector Signal Generator Research Articles

Error estimation of discrete formation method for optimal FTN signals

One of the branches of Faster than Nyquist (FTN) signaling providing transmission at the rate higher than “Nyquist limit” with insignificant energy losses includes optimal FTN pulses. These pulses have controllable level of intersymbol interference (ISI) and given time and spectral parameters. The efficiency of practical usage of these pulses depends on the errors of discrete formation method. In this work a guidance for estimating the minimum number of samples needed to meet the requirements for spectral and energy characteristics of optimal FTN signals is proposed. Simulation modeling and experiments with the help of vector signal generator have been held. It was found that to form optimal FTN pulse with duration Ts=2T not more than 16 samples are needed. In this case, energy losses relatively to continuous optimal FTN pulse are about 0.2 dB.

WmA-MiFN: A Weighted Majority and Auction Game Based Green Ultra-Dense Micro-Femtocell Network System

Power optimization and interference management in ultra-dense small cell based fifth-generation mobile networks are critical issues. This paper proposes a two-tier micro-femtocell based heterogeneous ultra-dense cellular network system, where femtocell allocation takes place inside the microcell based on user density. The femtocells form groups according to the adjacency and the leader selection of each group is performed using weighted majority game. Dedicated frequency allocation is performed for micro- and femtocell users though the leader of each femtocell group allocates frequencies to its follower femtocells based on auction game. Agilent EXG vector signal generator N5172B, EXA vector signal analyzer 9010A, and Agilent signal studio software are used for experimental purpose for performance evaluation of the proposed network. According to the simulation results, the proposed network decreases power transmission by 23%–41%, improves signal-to-interference-plus-noise ratio by 12%–39% and spectral efficiency by 10%–37% than the existing competing heterogeneous cellular network systems.

Experiment and Analysis for Air-to-Ground Channel in 400 MHz Band

Background/ Objectives: Recently, air-to-ground wireless communication systems have been used in various equipment such as unmanned aerial vehicle (UAV). In this paper, we analyze the air-to-ground channel in 400 MHz band with experiment using light aircraft. Methods/ Statistical analysis: The characteristics of the air-to-ground channel are analyzed as follows. We generate and store a pilot signal in commercial vector signal generator and an aircraft equipped with the signal generator takes off. As a pilot signal, Zadoff-Chu sequence is used for its good autocorrelation characteristics. In the ground station, the received waveform is stored by using spectrum analyzer. When an airplane approaches near the ground station, airplane transmits the pilot signal and the ground station begins to store the received signals. After completing the signal storing, air-to-ground channel analysis is performed. Findings: From the experiments, we obtained several hundreds of received waveforms, and those waveforms are used for statistical air-to-ground channel analysis. According to the analysis results, most of the measurement channels are single path or line of sight channels. However, in a certain measurement, multiple paths or non-line of sight channels are observed. Those results confirm that multipath environments exist at certain air-to-ground condition. The maximum number of multipath components is 4 and the maximum delay spread is 0.4 μsec. Therefore, when designing a wireless communication system considering air-to-ground environments, the design should consider 4-path fading channels and maximum delay spread over 0.4 μsec. When designing air-to-ground wireless communication systems such as aircraft and drone systems, the experimental and analyzed channels in this paper might be useful. Improvements/ Applications: In this paper, we analyze the air-to-ground channel characteristics of a mountainous area in Korea with field experiment using light aircraft. The analyzed channel characteristics are helpful to those who want to design wireless communication systems between aircraft to ground or UAV to ground. In addition, the analyzed channel can be used for verification of compatibility for the existing communication systems to air-to-ground applications.

Deep learning based EVM correction for RF receiver of vector signal analyser

This Letter presents a novel deep learning approach for optimising the receiver performance with respect to the error vector magnitude (EVM) metric, which was verified and evaluated by applying it to a self-developed proprietary vector signal analyser (VSA). A four-layer neural network was built and trained to estimate and correct the systematic error of the VSA receiver by using a calibrated commercially available vector signal generator as the training source. Experimental results show that the EVM performance of the self-developed VSA is improved and approaches that of a state-of-the-art VSA.

Validation of Potential Effects on Human Health of in Vivo Experimental Models Studied in Rats Exposed to Sub-Thermal Radiofrequency. Possible Health Risks Due to the Interaction of Electromagnetic Pollution and Environmental Particles

Studies are based on the exposure of Sprague-Dawley rats (250 male and 250 female rats) to electromagnetic fields (EMF) at different frequencies in standing and travelling wave chambers. Values of specific absortion rate (SAR) for all of these experiments were obtained from commercially available FDTD-based simulation software based on numerical phantom animals. An experimental radiation system was developed with a standing-wave cavity which keeps electromagnetic parameters constant while facilitating stress-free exposure of animals to non-thermal radiation. This makes it possible to directly measure the power absorbed by the animal and determine whole-body mean SAR according to weight. All studies using this setup were performed with global system for mobile communication (GSM) radiation at 900 MHz. The simple picrotoxin model made allow to identify morphological signs of neurotoxicity in rat brain tissue. Experiments involving travelling waves were done in a commercial Gigahertz Transverse ElectroMagnetic (GTEM) chamber connected to one or two vector signal generators (to carry single or multiple EMF exposure frequencies). In the diathermy model, rat thyroid and thymus exposed to 2.45 GHz radiation showed visible morphological and immune effects. Cellular stress in the cerebral cortex, the cerebellum or both seems to be more associated with the type of signal than with additive effects of combined frequencies. Finally, some hypothesis related with the future models about the ElectroMagnetic (EM) pollution are established. In an urban environmental that combines the electromagnetic and chemical pollution of environmental particles, cortical excitability, inflammatory response, and cell injury can be modified.

W-Band 8QAM Vector Millimeter-Wave Signal Generation Based on Tripling of Frequency Without Phase Pre-Coding

In this paper, we propose a W-band 8-quadrature-amplitude-modulation (8QAM) frequency tripling photonic vector millimeter-wave (mm-wave) signal generation method by using a phase modulator (PM) with only amplitude pre-coding. The PM is driven by 2-Gbaud 8QAM-modulated amplitude precoded signal at 25 GHz. Instead of phase pre-coding, we only need to reverse the real part of the signal at the receiver after photo detector (PD). The structure of the transmitter and the structure of the receiver are simple. The frequency tripling scheme is completed by numerical simulation, the output optical spectrum is consistent with the theoretical analysis, and bit-error-ratio (BER) curves indicate that the put forward 75 GHz 8QAM vector signal generation technique has good performance. The BER of 6 Gbit/s 75 GHz 8QAM vector mm-wave signal is below $3.8 \times 10^{-3}$ after 12 km optical fiber transmission. For all we know, it is the first time to report on the generation of high-order QAM photonic mm-wave signal with odd times of RF frequency by using a single external modulator.

QPSK Vector Millimeter-Wave Signal Generation Based on Odd Times of Frequency Without Precoding

In this paper, we propose a novel quadrature phase-shift keying (QPSK) vector millimeter-wave (mm-wave) signal generation based on odd times of frequency without precoding. The radio frequency (RF) vector signal generation module is universal for the generation of millimeter-wave signal with any odd frequency multiplication. Instead of phase precoding, the phases of electrical mm-wave signal are multiplied by the frequency multiplication number at the receiver after carrier phase estimation. The frequency tripling, quintupling, and septupling schemes are achieved by simulation, and bit-error-ratio curves demonstrate that the proposed QPSK vector mm-wave signal generation scheme works well.

Flexible photonic generation of frequency multiplication millimeter-wave vector signal based on dynamic pre-coding algorithm with dispersion compensation

The flexible photonic generation of millimeter-wave (mm-wave) vector signal adopting frequency multiplication enabled by two paralleled phase modulators and pre-coded radio frequency (RF) signals based on dynamic pre-coding algorithm is proposed and demonstrated. One driving signal has the original phase information and a phase deviation for dispersion compensation while the other signal has an opposite phase information and the same compensation phase. The amplitude depends on that of the regular vector symbol and the ratio of driving voltage to half-wave voltage of the phase modulator (PM). Two RF signals modulate the identical light waves from one laser via phase modulators respectively. The light waves are then transmitted over a fiber link after the selection of proper orders of harmonics by the wavelength selective switch (WSS). At the receiver, the optical signal is applied directly to a photodetector (PD) to generate the mm-wave vector signal at the desired frequency. The simulation of proposed scheme with radio over fiber (RoF) link transmission has been build. The result shows that the error vector magnitude (EVM) of generated 60 GHz, 100 GHz, and 140 GHz 16 quadrature-amplitude-modulation (QAM) signals of 1 Gb/s is no more than 20% after 80 km fiber transmission when the power into PD is no less than −10 dBm under ideal condition.

Implementation of a Multi-Gbit/s and GFDM-based Optical-Wireless 5G Network

We report the implementation of an optical-wireless 5G network based on generalized frequency division multiplexing (GFDM) and multi-Gbit/s communication. Dual-drive Mach-Zehnder modulator was employed, enabling simultaneously RF signals transport using two 5G candidate bands, namely: 26 GHz band for providing a femtocell with 2 Gbit/s throughput; 700 MHz band for enabling rural access applying a supercell. A vector signal generator provides the broadband 26 GHz signal. The Brazilian GFDM-based 5G transceiver generates the lower-frequency signal, with the advantage of low out-of-band emission. An experimental digital performance analysis illustrates the suitability of the proposed solution to address 5G requirements.

Photonic Vector Signal Generation Based on OEO and Optical Coherent QPSK Modulation

A novel scheme for photonic vector signal generation based on a self-starting optoelectronic oscillator (OEO) and optical coherent quadrature phase-shift keying (QPSK) modulation is proposed and experimentally demonstrated. The optical output sidebands of the OEO are employed for optical heterodyne mixing, where one first-order sideband is modulated by QPSK baseband data using a dual-parallel Mach–Zehnder modulator, followed by coherent detection so as to directly generate frequency-doubled K-band vector signals. In the experiment, a 19.9 GHz QPSK modulated vector signal with a bit rate of 100 Mb/s is generated when the OEO operates at 9.95 GHz. The generated signal is back demodulated with error vector magnitude (EVM) less than 7%.

Focus on test, measurement, software, and instrumentation

Focus on test, measurement, software, and instrumentation

Emulation of 3GPP SCME power‐delay profiles for characterisation of multiple‐input–multiple‐output antenna in reverberation chamber

A simple yet effective technique for emulating third generation partnership project spatial channel model extended (3GPP SCME) power-delay profiles in a reverberation chamber is investigated. Through use of a conventional vector signal generator and oscilloscope, urban macro- and micro-environments containing several strong reflections are replicated with <;4% error. The generation of the input power delay profiles, the measurement set-ups in the reverberation chamber and the emulation optimisation process are described rigorously. In experiment, it is demonstrated that the averaging procedure is essential for acquisition of optimum results in the reverberation chamber. The radiation efficiency and correlation coefficient of a multiple-input-multiple-output (MIMO) antenna are also defined for different emulated multipath channels. The calculated results verify the efficacy of the proposed emulation method for MIMO antenna characterisation.

Photonic generation of frequency-quadrupling millimeter-wave vector signal based on balanced detection without precoding

Photonic frequency-quadrupling millimeter-wave (mm-wave) vector signal generation is proposed by balanced detection without precoding. A dual-polarization quadrature phase shift keying (DP-QPSK) modulator is the main component of the scheme. In the DP-QPSK modulator, An optical carrier and ± 4st-order optical sidebands can be obtained in one QPSK modulator, while the other QPSK modulator driven by 16QAM baseband electrical I/Q data. After balanced detection, a 16QAM vector signal can be obtained by frequency-quadrupling. The proposed scheme can reduce the complexity of transmitter digital signal processing. By adjusting the sub modulators of the DP-QPSK modulator, a 4 Gbaud baseband 16QAM vector signal can be generated at 40 GHz by frequency-quadrupling. In addition, after 20 km single-mode fiber (SMF) transmission, the constellation, eye diagrams and the BER curves of the frequency-quadrupling mm-wave vector signal perform well.

Indoor wideband directional millimeter wave channel measurements and analysis at 26 GHz, 32 GHz, and 39 GHz

AbstractThis paper presents details of the wideband directional propagation measurements of millimeter‐wave (mmWave) channels in the 26 GHz, 32 GHz, and 39 GHz frequency bands in an indoor typical office environment. More than 14 400 power delay profiles (PDPs) were measured across the 26 GHz band and over 9000 power delay profiles have been recorded for the 32 GHz and 39 GHz bands at each measurement point. A mmWave wideband channel sounder has been used, where signal analyzer and vector signal generator were employed. Measurements have been conducted for both co and cross‐antenna polarization. The setup provided 2 GHz bandwidth and the mechanically steerable directional horn antenna with 8 degrees beamwidth provides 8 degrees of directional resolution over the azimuth for 32 GHz and 39 GHz, whereas 26 GHz measurement setup provides the angular resolution of 5 degrees. Measurements provide path loss, delay, and spatial spread of the channel. Large‐scale fading characteristics, RMS delay spread, RMS angular spread, and angular and delay dispersion are presented for 3 mmWave bands for the line‐of‐sight scenario.

Integration of a GFDM-Based 5G Transceiver in a GPON Using Radio Over Fiber Technology

This paper reports the integration and experimental performance analysis of a GFDM-based 5G transceiver in a gigabit passive optical network (GPON), using radio over fiber technology. The proposed architecture enables to simultaneously transport two 5G candidates RF signals through an active GPON under real channel conditions. One signal is generated by a GFDMbased 5G prototype transceiver at 735 MHz, whereas the second one is synthetized by a vector signal generator at 26 GHz. A dualdrive Mach-Zehnder modulator has been utilized in the optical line terminal to modulate both signals, with the purpose of mitigating the interference between them. Particularly for the GFDM-based 735 MHz signal, a modulation error ratio (MER) of 40 dB has been obtained at RF-driven signal up to -9 dBm. Furthermore, the use of a digital predistortion scheme has been efficiently employed to reduce the impact of the nonlinear distortions and enhance MER. The 26-GHz RF signal, aimed for the 5G millimeter wave band, has been investigated as a function of error vector magnitude (EVM) for bitrates up to 1 Gbit/s. EVMRMS of 2.18% and 5.70% have been obtained for 100 Mbit/s and 1 Gbit/s, respectively. Finally, the latency and throughput measurements of the baseband signal originally running over GPON have shown no significant penalties.

Comparison of a genetic programming approach with ANFIS for power amplifier behavioral modeling and FPGA implementation

Accurate modeling of power amplifiers (PA) is of upmost importance in the design process of wireless communication systems where a high linearity and efficiency is required. To deal with the nonlinear behavior of PAs effectively a linearization stage is applied to minimize the distortions of in-band and adjacent transmission channels, which translate to an improvement of the signal integrity and the operation cost of the transmitter system. This paper presents a method based on genetic programming with a local search heuristic (GP-LS) to emulate the electrical memory effects by using the characteristic conversion curves of the radio frequency (RF) PA NXP Semiconductor of 10 W GaN HEMT working at 2.34 GHz. This method is compared with an Adaptive Neuro-Fuzzy Inference Systems (ANFIS) through several performance metrics (NMSE, MAE and correlation coefficient), with GP-LS achieving a better modeling accuracy. Moreover, the models produced by GP-LS permit a reduction in the required hardware resources, when it is implemented on a Field-Programmable Gate Array through the DSP Builder tool. The models are derived using a data-driven approach, posed in two different ways. Firstly, experiments are performed using a testbed Arria V GX for a flexible vector signal generation that provides the raw data of the PA characterization using an LTE-Advanced signal with 10-MHz bandwidth. Secondly, the modeling is derived from a filtered version of the data and then adding a high-frequency signal as a post processing step to approximate the true behavior of the system. In both cases, the models are generated with ANFIS and GP-LS, performing extensive logic-based simulations and implementing the models on a Cyclone III development board. Both approaches are compared based on accuracy and required hardware resources, with GP-LS substantially outperforming ANFIS. These results suggest that the GP-LS models can be implemented in a digital predistortion chain and used in the linearization stage for a RF-PA.

Pre-coding assisted generation of a frequency quadrupled optical vector D-band millimeter wave with one Mach-Zehnder modulator.

We propose QPSK millimeter-wave (mm-wave) vector signal generation for D-band based on balanced precoding-assisted photonic frequency quadrupling technology employing a single intensity modulator without an optical filter. The intensity MZM is driven by a balanced pre-coding 37-GHz QPSK RF signal. The modulated optical subcarriers are directly sent into the single ended photodiode to generate 148-GHz QPSK vector signal. We experimentally demonstrate 1-Gbaud 148-GHz QPSK mm-wave vector signal generation, and investigate the bit-error-rate (BER) performance of the vector signals at 148-GHz. The experimental results show that the BER value can be achieved as low as 1.448 × 10-3 when the optical power into photodiode is 8.8dBm. To the best of our knowledge, it is the first time to realize the frequency-quadrupling vector mm-wave signal generation at D-band based on only one MZM without an optical filter.

EXTRAPOLATION METHOD FOR MAXIMAL AND 24-H AVERAGE LTE TDD EXPOSURE ESTIMATION.

The Long-Term Evolution (LTE) system represents the evolution of the Universal Mobile Telecommunication System technology. This technology introduces two duplex modes: Frequency Division Duplex and Time Division Duplex (TDD). Despite having experienced a limited expansion in the European countries since the debut of the LTE technology, a renewed commercial interest for LTE TDD technology has recently been shown. Therefore, the development of extrapolation procedures optimised for TDD systems becomes crucial, especially for the regulatory authorities. This article presents an extrapolation method aimed to assess the exposure to LTE TDD sources, based on the detection of the Cell-Specific Reference Signal power level. The method introduces a βTDD parameter intended to quantify the fraction of the LTE TDD frame duration reserved for downlink transmission. The method has been validated by experimental measurements performed on signals generated by both a vector signal generator and a test Base Transceiver Station installed at Linkem S.p.A facility in Rome.

Digital dispersion pre‐compensation based on intensity modulator and phase modulator for PAM‐4 in short‐reach fibre communications

High-speed PAM-4 is a promising way for future low-cost short-reach fibre communications. However, for 1550 nm transmission with the lowest attenuation for standard single-mode fibre (SSMF), the fibre dispersion-induced inter-symbol interference (ISI) becomes non-linear in direct detection. Dispersion pre-compensation at the transmitter side is necessary to avoid such non-linear ISI. Different from previous methods to generate the vector signal from dispersion pre-compensation using IQ modulators, in this study a digital dispersion pre-compensation (DDPC) scheme based on an intensity modulator (IM) plus a phase modulator (PM) is studied. Taking into account the digital-to-analogue converter (DAC) bandwidth limit on the vector signal generation, anti-aliasing filtering on both the magnitude signal and the phase signal should be applied. The error rate performance of the IM-PM based DDPC scheme is analysed in detail using numerical simulations. For 50 Gb/s PAM-4 transmission at 1550 nm over SSMF, over 50 km fibre transmission can be supported if the two DACs have enough bandwidth larger than 17.5 GHz. If the DAC bandwidth is limited to 15 GHz, it is also possible to transmit over 20 km SSMF. Meanwhile, it is verified that practical 5-bit DAC resolution is enough for the IM-PM based DDPC scheme to work for a wide range of SSMF lengths.

Optimization of Precoding Phase Distribution for Frequency-Multiplication Vector Signal Generation

Generation of optical vector millimeter-wave (mm-wave) signal based on Mach–Zehnder intensity modulator with frequency multiplication can reduce bandwidth requirement of optical and electrical components. A phase precoding scheme with constellation optimization is experimentally demonstrated in one 144-GHz mm-wave signal generation system with frequency sextupling. The bit-error-ratio (BER) performance at one BER of 3.8 × 10–3, hard-decision forward-error-correction threshold, is improved by over 3 dB using this novel scheme for 4-Gbaud quadrature-phase-shift-keying signal at D-band (110–170 GHz).