Vector Mm-wave Signal Research Articles

Photonic-assisted high-order vector millimeter-wave signal generation enabled by DSM.

We propose an optical dual-single-sideband (dual-SSB) modulated 16384-quadrature amplitude modulation (QAM) photonic vector millimeter-wave (mm-wave) signal generation scheme based on delta-sigma modulation (DSM). With the aid of the DSM, the severe nonlinear distortion of envelope detection for high-order QAM modulation signals in wireless communication can be effectively resolved. For the validation of our proposed scheme, we experimentally demonstrate the generation of a 40 GHz 16384-QAM orthogonal frequency division multiplexing (OFDM) photonic vector mm-wave signal and transmission over a 25-km standard single-mode fiber (SSMF), and a 1-m wireless link with the bit error ratio (BER) reaches the hard-decision forward-error-correction (HD-FEC) threshold of 3.8 × 10-3.

Multifrequency Vector Mm-Wave Signal Generation with No Optical Filtering Based on One Dual-Arm MZM with Phase Factor Optimization

In order to reduce the number of devices in and cost of a multifrequency vector millimeter-wave (mm-wave) signal generation system, we propose a novel scheme for multifrequency vector mm-wave signal generation based on one dual-arm Mach-Zehnder modulator (MZM) without optical filtering. This scheme utilizes the carrier suppression modulation of a single modulator, without the need for optical filtering and combines precoding technology to generate high-frequency QPSK and 16 QAM mm-wave signals. The transmitter is applied with precoding technology to make the frequency multiplying vector mm-wave signal display regular vector modulation at the receiver, and the system is optimized with a phase factor to ensure that the phase distribution of QPSK signal at the receiver is symmetrical. We demonstrated the generation of 4-Gbaud 76 GHz QPSK and 16 QAM vector mm-wave signals through simulation. The simulation results show that, at a fiber transmission distance of 12 km, when the launched optical power of the PD is greater than −20.535 dBm, the bit error ratio (BER) of the QPSK signal is lower than the hard-decision forward error correction (HD-FEC) threshold of 3.8 × 10−3. At a fiber transmission distance of 10 km, when the launched optical power of the PD is greater than −18.637 dBm, the BER of 16 QAM signal is also lower than 3.8 × 10−3.

Photonic filter-free adjustable frequency sextupling scheme for V-band vector mm-wave signal generation based on a DP-MZM with precoding

In this work, a new filter-free adjustable scheme for the generation of frequency sextupling vector millimeter-wave (mm-wave) signal without optical filter which can widen the adjustable frequency range. In the process of vector mm-wave frequency multiplication, the frequency is linearly multiplication and the phase would be simultaneous linearly multiplication, which makes the information carried by the phase distorted. Phase precoding is employed to eliminate constellation overlapping caused by phase multiplication. Simulations are done to generate V-band 60 GHz sextupling phase shift keying (QPSK) modulated vector mm-wave signals using a 10 GHz radio frequency source and the BER performance is analyzed in detail. The results show that BER of the generated 5/10-Gbit/s vector millimeter-wave signal is below 3.8×10−3, when the input optical power for into photo-detector is higher than −20.67 dBm.

Photonics aided vector millimeter-wave signal generation without DAC at W-band

In this paper, a novel scheme to generate a high-order QAM W-band mm-wave signal is proposed, which avoids the usage of expensive and power hungry digital-to-analog converter (DAC). We numerically simulate m2-QAM mm-wave signal generation and investigate the influences of phase shift and SNR on the performance of the generated W-band signals. The numerical result shows that both SNR and the modulation order m are important factors which decide the quality of generated vector mm-wave signals. Besides, we experimentally demonstrate 10 Gb/s @80 GHz QPSK signal generation based on photonic-aided frequency quadrupled generation principle, which handles the phase noise issue effectively. Moreover, 10 Gb/s @80 GHz QPSK signal transmission over 1-km DSF and 1-m wireless link is also achieved. The experiment results indicate that BER can achieve 7% hard-decision forward error correction (HD-FEC) threshold of 3.8 × 10−3 when the optical power is above −5 dBm. Due to avoiding a bandwidth limited DAC, our proposed W-band QAM vector mm-wave signal generation with a simple structure is promising for the future high-speed 5G ROF-based communication application and beyond.

QAM Vector mm-Wave Signal Generation Based on Optical Orthogonal Polarization SSB Scheme By a Single Modulator

Millimeter-wave (mm-wave) has become an attractive technique in the fifth generation (5G) because it meets the demand of explosive increase in data traffic. In this study, we propose and demonstrate the generation of quadrature amplitude modulated (QAM) vector mm-wave signal employing optical orthogonal polarization single sideband (SSB) modulation, which employs a single polarization-division multiplexing MachZehnder modulator (PDM-MZM). Based on our scheme, there is no inter-band crosstalk and inter-polarization signal-signal beat interference (SSBI). In our scheme, the two sub-modulators in PDM-MZM both work within their linear modulation range. After PDM-MZM, the two optical SSB signals are orthogonally polarized. By using an interleaver (IL), the low sideband (LSB) and upper sideband (USB) optical signals in the two polarization directions are extracted respectively. In addition, IL also suppresses the unwanted components of the opposite orthogonally polarized signal. We demonstrate the generation of two independent 28 GHz 12 Gbaud quadrature-phase-shift-keying (QPSK) and 6 Gbaud 16-ary quadrature amplitude modulation (16-QAM) signals. 65 km single-mode fiber (SMF) transmission is achieved with the bit-error-rate (BER) below 20% forward-error-correction (FEC) soft-decision threshold of 2.4 102 without dispersion compensation. We also demonstrate the generation of two independent 28GHz 1 Gbaud 64-QAM signals and transmission SMF over 10-km with the BER below 20% FEC soft-decision threshold of 2.4 102. Since the LSB and USB signals are on opposite polarization sides, the inter-band crosstalk and the inter-polarization SSBI can be significantly reduced. Because SSB modulation scheme is deployed, our proposed QAM vector signal generation system is robust to fiber dispersion.

W-band Millimeter-Wave Signal Generation Based on Frequency Quadrupling and Nonlinearities Tolerant Modulation

In this article, we present a W-band (3, 1) millimeter-wave vector signal generation based on frequency-quadrupled modulation and nonlinearities tolerant modulation by one Mach–Zehnder modulator (MZM). Despite the phase changes, the constellation and sequence of the received (3, 1) signal is consistent with the original regular signal after the detection of the photo-detector (PD). The obtained (3, 1) constellation has better performance compared to pre-coded quadrature phase shift keying (QPSK) constellation at the receiver end, and effectively reduces system complexity and cost. The frequency-quadrupled scheme is experimentally completed with different date rates at 2 and 4-Gbaud. The bit-error-ratios (BERs) results show that the BER performance of (3, 1) signal is superior to the pre-coded QPSK, and it is below the 7% hard-decision forward-error-correction (HD-FEC) threshold of 3.8 × 10−3 over 5 and 10 km single-mode-fiber (SMF) transmission , which demonstrates that the generation of (3, 1) vector mm-wave signal based on proposed frequency-quadrupled scheme and nonlinearities tolerant modulation can be used in our system.

A scheme to generate 16QAM-OFDM vector mm-wave signal based on a single MZM without optical filter and precoding

In this paper, a novel and relatively simple scheme for generation of high-quality 16QAM-modulated multi-carrier vector millimeter-wave (mm-wave) was proposed, which was only based on a single Mach–Zehnder modulator (MZM), while the precoding technique and optical filter were not needed. At the transmitter, electrical dual single sideband (SSB) signals were generated by a digital signal processing (DSP) module, in which the frequency of modulated signals could be adjusted flexibly. Employing the generated dual-SSB signal to drive a push–pull MZM biased at Quad point, optical dual-SSB 16-QAM OFDM signals were obtained. After a photodiode, higher frequency OFDM vector mm-wave signals were achieved by beating. Based on the proposed method, a simulation platform of generating 30 GHz 16QAM OFDM vector mm-wave signals was set up and the performance of the generated OFDM vector mm-wave was analyzed. The results show that the bit-error ratio of the transmission system were less than hard decision forward-error correction threshold of 3.8×10−3, which demonstrates that the generation of OFDM vector signal can work well.

Photonic filterless scheme to generate V-band OFDM vector mm-wave signal without precoding

A novel and relatively simple scheme for the generation of high-quality V-band (50–75 GHz) OFDM vector millimeter-wave (mm-wave) is presented, which is only enabled by a dual-parallel Mach–Zehnder modulator (DP-MZM). In this scheme, precoding technique and optical filter are not needed. At the transmitter, electrical dual single sideband (SSB) signals are generated by a digital signal processing (DSP) module, in which the frequency of modulated signals could be adjusted flexibly. The two push–pull sub-MZMs are biased at quadrature transmission points to generate dual optical single sideband (OSSB) signals. The DP-MZM is biased at null transmission point to suppress the center optical carrier and an asymmetrical OSSB signal can be obtained. Then, a higher frequency OFDM vector mm-wave signal is generated after the beating of the asymmetrical OSSB signal at the photodiode. Theoretical analysis is given out in the paper, and V-band OFDM vector mm-wave at the frequency of 65 GHz is generated in the simulation. The results show that the bit-error ratio (BER) of the transmission system is smaller than forward-error correction (FEC) threshold of 3.8×10−3, when the optical power into photodiode (PD) of 10/20/30 Gbaud cases are not less than −19.13 dB, −17.81 dB, −16.50 dB respectively after 50km single model fiber transmission.

A New Scheme to Generate Multi-Frequency Mm-Wave Signals Based on Cascaded Phase Modulator and I/Q Modulator

We propose a new scheme to generate multi-frequency vector mm-wave signals based on cascaded phase modulator and I/Q modulator by adopting independent-sideband (ISB) modulation scheme. Driven by a single frequency RF (Radio frequency) source, the phase modulator (PM) generates multi-frequency optical carriers with a constant frequency interval, which is used as the optical input of the I/Q modulator. The electrical signal driving the I/Q modulator is composed of two parts, one vector-modulated single side-band (SSB) QAM signal and one unmodulated SSB RF signal, and the two signals locate at different sides of zero frequency. The output of I/Q modulator contains of several multi-frequency optical side-bands and suppressed optical carriers. The optical carriers are effectively suppressed by using the ISB modulation scheme. Two optical sidebands at different frequencies are selected by a wavelength select switch (WSS) and beaten in the photodetector (PD), then multi-frequency vector mm-wave signals are generated with high flexibility, and the frequency can be up to 400GHz. We experimentally demonstrate 133GHz D-band multi-frequency vector mm-wave signal over 80-km SMF-28 wireline transmission and 10-m wireless delivery with bit rate up 18.4x2=36.8Gb/s.

80-GHz RoF Based on Push–Pull Modulator

A novel push-pull modulator based scheme to generate W-band millimeter-wave (mm-wave) vector signal was proposed and experimentally demonstrated. Related to an I/Q modulator, push-pull modulator has the advantages of simple architecture, small insertion loss and low cost. Through combining one 40 GHz upper sideband (USB) using a quadrature-phase-shift-keying (QPSK) modulation with a −40 GHz unmodulated lower sideband (LSB), a QPSK modulated 4 G-Baud 80 GHz single sideband vector mm-wave signal was successfully generated.

Photonic vector mm-wave signal generation by optical dual-SSB modulation and a single push-pull MZM.

We propose and experimentally demonstrate single-sideband (SSB) photonic vector millimeter-wave (mm-wave) signal generation enabled by optical dual-SSB modulation and a single push-pull Mach-Zehnder modulator (MZM). We use software-based digital signal processing to generate the dual-SSB driving signal for the push-pull MZM. The dual-SSB driving signal has a vector-modulated sideband and an unmodulated sideband, which are spaced by our desired mm-wave carrier frequency. After linear modulation of the push-pull MZM, optical filtering, and single-ended photodiode detection, we can get an electrical mm-wave signal displaying the same vector modulation as the aforementioned vector-modulated sideband. Based on our proposed scheme, we experimentally demonstrate the generation and transmission of a 40GHz mm-wave signal carrying 1Gbaud 16-ary quadrature-amplitude-modulation or 4Gbaud quadrature-phase-shift-keying transmitter data over a 10km single-mode fiber-28 and 0.5m air-space link, with a bit-error-ratio less than the hard-decision forward-error-correction threshold.

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.

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.

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.

W-Band Vector Millimeter-Wave Signal Generation Based on Phase Modulator With Photonic Frequency Quadrupling and Precoding

We experimentally demonstrate W-band vector millimeter-wave (mm-wave) signal generation and its air space transmission, from constant-modulus quadrature phase shift keying modulation to multimodulus 8-ary quadrature amplitude modulation/16-ary quadrature amplitude modulation (8QAM/16QAM) modulation, employing a photonic frequency-quadrupling scheme enabled by a single phase modulator and precoding technique. As far as we know, it is the first time to realize W-band 8QAM/16QAM vector mm-wave signal generation based on a single phase modulator with photonic frequency multiplication. We also investigate by numerical simulation and experiment the effect of the radio-frequency (RF) driving peak-to-peak voltage of the phase modulator on the performance of the generated vector mm-wave signal, and find that there exists an optimal RF driving peak-to-peak voltage for the best performance of the generated vector mm-wave signal, which agrees well with our theoretical analysis.

Probabilistic shaping for ROF system with heterodyne coherent detection

We investigate and compare the performance of normal and probabilistic shaping (PS) 16-ary quadrature amplitude modulation (16QAM) in a photonic vector millimeter-wave (mm-wave) signal generation system adopting heterodyne coherent detection. And we obtain a better bit-error ratio (BER) performance in the PS 16QAM scheme compared to the normal 16QAM scheme in the simulation. We also for the first time experimentally demonstrate the feasibility of PS-polarization-division-multiplexing 16QAM in a photonic vector mm-wave signal generation system employing heterodyne coherent detection. We obtain the same BER in PS and normal schemes with the PS scheme providing a higher bit rate. Then we experimentally carry out the performance investigation of PS in a 16QAM-modulated radio over fiber system with 40 m wireless transmission.

Phase Factor Optimization for QPSK Signals Generated from MZM Based on Optical Carrier Suppression

We propose and experimentally demonstrate one novel scheme to improve the performance of the vector millimeter-wave (mm-wave) signal generated by intensity modulator based on optical carrier suppression. The phase distribution of the vector mm-wave signal after one square-law photodiode detection becomes nonuniform. We optimize the phase factor at the transmitter side and make the phase distribution of the quadrature phase-shift keying signal to be symmetrical at the receiver.

Generation and Heterodyne Detection of >100-Gb/s $Q$ -Band PDM-64QAM mm-Wave Signal

We experimentally demonstrate a hardware- and spectral-efficient large-capacity single-carrier radio-over-fiber system at $Q$ -band (33–50 GHz), employing high-level polarization-division-multiplexing 64-ary quadrature-amplitude-modulation (PDM-64QAM) modulation and heterodyne coherent detection. In our demonstrated system, up to 10-GBd (120-Gb/s) PDM-64QAM vector millimeter-wave (mm-wave) signal at 37.5 GHz can be generated and delivered over 1-m wireless distance, with a bit-error ratio (BER) less than the hard-decision forward-error-correction (FEC) threshold of $3.8\times 10^{\mathrm {-3}}$ . Our demonstrated system can also generate up to 16-GBd (192-Gb/s) PDM-64QAM vector mm-wave signal at 37.5 GHz, with a BER less than the soft-decision FEC threshold of $1\times 10^{\mathrm {-2}}$ . During the receiver digital signal processing, the employment of large-tap decision-directed least-mean-square equalization after carrier recovery significantly improves the system performance. To the best of our knowledge, this is the first time to demonstrate single-carrier PDM-64QAM modulated wireless mm-wave signal delivery.