Quadrature Phase Shift Keying Modulation Research Articles

Design and Test of Offset Quadrature Phase-Shift Keying Modulator with GF180MCU Open Source Process Design Kit

This article explores the evolution of integrated circuits (ICs), highlighting the fundamental role of open source Electronic Design Automation (EDA) tools in their development. It describes the IC’s design flow, differentiating between Front-end and Back-end design stages, and details the process of implementing the digital stage in offset quadrature phase-shift keying (OQPSK) modulation in an IC, including its hardware description language (HDL), the implementation test in the field-programmable gate array (FPGA), and the physical layout using the first manufactured open source process design kits (PDKs) in Global Foundries’ 180 nm, as well as the use of OpenLane and Caravel. To conclude, the results of the physical tests obtained from the digital modulation are presented, as well as the performance of the raised cosine shaping filter.

A Temporal Methodology for Assessing the Performance of Concatenated Codes in OFDM Systems for 4K-UHD Video Transmission

The communication channel is a critical part of the process of information degradation. In the 4K ultra-resolution video transmission domain, the communication channel is a crucial part where information degradation occurs, inevitably leading to errors during reception. To enhance the transmission process in terms of fidelity, advanced technologies such as digital video broadcasting terrestrial (DVB-T) and its evolutionary successor, digital video broadcasting terrestrial second generation (DVB-T2), are utilized to mitigate the effects of data transmission errors. Within this scenario, this research presents an innovative methodology for the temporal analysis of 4K ultra-resolution video quality under the influence of additive white Gaussian noise (AWGN) and Rayleigh channels. This analytical endeavor is facilitated through the application of concatenated coding schemes, specifically, the Bose–Chaudhuri–Hocquenghem concatenated low-density parity check (BCH-LDPC) and Reed–Solomon concatenated convolutional (RS-CONV) coders. A more comprehensive understanding of video quality can be attained by considering its temporal variations, a crucial aspect of the ongoing evolution of technological paradigms. In this study, the Structural Similarity Index (SSIM) serves as the main metric for quality assessment during simulations. Furthermore, the simulated Peak Signal-to-Noise Ratio (PSNR) values validate these findings, exhibiting consistent alignment with the SSIM-based evaluations. Additionally, the performance of the BCH-LDPC significantly outperforms that of RS-CONV under the 64-QAM modulation scheme, yielding superior video quality levels that approximate or surpass those achieved by RS-CONV under QPSK (Quadrature Phase Shift Keying) modulation, leading to an increase in spectral efficiency. This enhancement is evidenced by SSIM gains exceeding 78% on average. The computation of average gains between distinct technologies in video quality analysis furnishes a robust and comprehensive evaluation framework, empowering stakeholders to make informed decisions within this domain.

All-Optical Modulation Format Conversions from PAM4 to QPSK and 16QAM Using Silicon-Rich Nitride Waveguides

Quadrature phase-shift keying (QPSK) and 16-quadrature amplitude modulation (16QAM) formats are deployed in inter-data center networks where high transmission capacity and spectral efficiency are required. However, in intra-data center networks, a four-level pulse amplitude modulation (PAM4) format is deployed to satisfy the requirements for a simple and low-cost transceiver configuration. For the seamless and effective connection of such heterogeneous networks without an optical-electrical-optical conversion, an all-optical modulation format conversion technique is required. In this paper, we propose all-optical PAM4 to QPSK and 16QAM modulation format conversions using silicon-rich nitride waveguides. The successful conversions from 50-Gbps-class PAM4 signals to 50-Gbps-class QPSK and 100-Gbps-class 16QAM signals are demonstrated via numerical simulations.

Performance analysis of atomic magnetometer and bandwidth‐extended loop antenna in resonant phase‐modulated magnetic field communication system

AbstractTelecommunications through an electrically conductive medium require the use of carrier bands with very‐low and ultralow frequencies to establish radiofrequency links in harsh environments. Recent advances in atomic magnetometers operating at very‐low frequencies have facilitated the reception of digitally modulated signals. We demonstrate the transmission and reception of quadrature phase‐shift keying (QPSK) signals using a multi‐resonant loop antenna and atomic magnetometer, respectively. We report the measured error vector magnitude according to the symbol rate for QPSK modulation and analyze the bandwidth of a receiver based on the atomic magnetometer. The multi‐resonant loop antenna noticeably enhances the bandwidth by over 70% compared with a single‐loop antenna. QPSK modulation for a carrier frequency of 20 kHz and symbol rate of 150 symbols per second verifies the feasibility of demodulation, and the measured error vector magnitude and signal‐to‐noise ratio are 7.29% and 30.9 dB, respectively.

Image transmission performance analysis through free space optical communication link using coherent QPSK modulation under various environmental conditions

AbstractFree space optics (FSO) technology has been used recently in many applications due to its various advantages such as high bandwidth, easy deployment, high security, free installation license and immunity to electromagnetic interference. However, this type of communication is vulnerable to meteorological conditions such as rain, haze and fog which significantly degrade the system's efficiency. To enhance the effectiveness of the FSO systems, Quadrature Phase Shift Keying (QPSK) modulation based on coherent detection constitutes a promising technique for achieving high spectral efficiency and long‐distance FSO links with the characteristics of low‐cost implementation and simple design. This work aims to investigate the performance of FSO communication links on image transmission under the presence of atmospheric attenuations. A comparative study has been made using QPSK modulation scheme and on–off‐keying (OOK) modulation scheme to estimate the maximum range that was used to recover an RGB transmitted image over an FSO link under different meteorological weathers. The obtained results clearly show that the quality of the received image has degraded significantly during transmission through free space yielding to limit the propagation range. Moreover, the proposed FSO communication system performs well when using QPSK modulation rather than OOK modulation in different environmental conditions. Thus, to improve the quality of the received image under adverse fog weather condition, high power and small beam divergence angle have been suggested to increase system's performance. The proposed solution increases the communication range of the FSO link by 230 m and 100 m for moderate and heavy fog, respectively.

All-optical matching structure for multi-order modulation formats

With the development and popularity of the Internet, network security has become a popular topic. The traditional solution for screening the security of network information is to convert the signal transmitted in the optical fiber into an electrical signal through an optical conversion. Then we perform symbol matching within the electronic firewall to determine whether the signal is a risk. However, due to the limitation of carrier recovery time in the semiconductor, the photoelectric converter cannot handle signals with too high rate, and it also causes a large power consumption. To improve the efficiency and scalability of signal matching, we propose an all-optical matching structure. This structure can identify the position of the target sequence in the input data sequence in the all-optical environment, and the structure is suitable for any amplitude and phase modulation format. The matching result of each bit of the target sequence and input data sequence is obtained by phase delay and interference. Then the matching result of each bit of the target sequence and input data sequence is integrated by logic AND gate, regenerator, and delay line. Finally, the matching result between the whole target sequence and the input data sequence is obtained. This structure can avoid photoelectric transformation and processes the signal directly at the optical domain, which greatly reduces the consumption of time and energy. We use VPItransmissionMaker software to simulate and verify the structure. The length of the input signal during the simulation is 8 bits, the length of the target signal is 4 bits, and the transmission rate of the signal is 100 GBaud. We simulated the binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), 8-phase shift keying (8PSK), and 16 quadrature amplitude modulation (16QAM) modulation formats and analyzed the noise performance of the system. The results show that the structure can achieve all-optical matching of high-speed optical signals in BPSK, QPSK, 8PSK, and 16QAM modulation formats and has good anti-noise performance.

Performance analysis of wireless transmission of compressed images using DCT‐OFDMA system with different compression schemes

AbstractTransmitting images over an Orthogonal Frequency Division Multiplexing Access (OFDMA) system poses a significant challenge. The process entails sending a substantial amount of data, which consumes a significant amount of bandwidth. Consequently, compressing the transmitted image becomes essential to reduce the required bandwidth. The aim of this paper is to examine and analyse the wireless transmission of a compressed image via Discrete Cosine Transform (DCT‐OFDMA). A comparison is made with Discrete Fourier Transform (DFT‐OFDMA), across various subcarrier mapping schemes (localized and inter‐leaved), and different modulation schemes (16 Quadrature Amplitude Modulation (16QAM) and Quadrature Phase Shift Keying (QPSK)) using vehicular A, Stanford University Interim (SUI3), and uniform channel models. To evaluate the performance of the system, the minimum Signal‐to‐Noise Ratio (SNR) necessary to recover the transmitted compressed image is calculated. This work considers nine standard compression techniques. The results are carried out using the MATLAB simulator. According to the simulation results, the minimum SNR required to recover the transmitted compressed image was found to be 19 dB. This result was achieved when using Discrete Cosine Transform‐Loaclized‐Orthogonal Frequency Division Multiplexing Access (DCT‐LOFDMA) with QPSK modulation and set partitioning in hierarchical trees (SPIHT) compression method over the SUI3 channel model. Moreover, it was observed that the DCT‐LOFDMA and DFT‐IOFDMA systems attained equal SNR while utilizing the SPIHT_3D compression technique and QPSK modulation on the SUI3 channel model. Overall, the results suggest that the performance of DCT‐based localized OFDMA is somewhat superior to DFT‐based localized OFDMA, particularly when utilizing the SUI3 channel model and the QPSK modulation scheme. Therefore, it is feasible to transmit and receive a compressed image effectively over an OFDMA system with DCT.

Quadrature Phase-Shift Keying Modulation With Random Coding Pulse for Long-Range ϕ-OTDR

Transient effect in erbium-doped fiber amplifier (EDFA) restricts the application of the phase-sensitive optical time-domain reflectometry (ϕ-OTDR) system with coding probe pulse (CPP) in long-distance vibration sensing. In this paper, a CPP modulation scheme based on phase coding is proposed to suppress the amplitude distortion after optical amplification. Quadrature phase-shift keying (QPSK), which has a high spectrum utilization efficiency, is designed on a I/Q modulator. The random sequence CPP is used in this system, because of the single coding sequence, the signal-to-noise ratio (SNR) can be improved without loss of the sensing bandwidth. Experimental results prove the effectiveness of the scheme. Compared to the conventional modulation scheme at a 50 mW pump power, the distortion coefficient of the CPP after amplification decreases from 57.67% to 9.23%, and the signal-to-interference ratio (SIR) increases from 13.89 dB to16.67 dB. Without distributed amplification, the proposed system successfully located the vibration at 85.652 km under the carrier period of 40 ns, and the SNR of the demodulated signal is up to 21.99 dB.

Frequency-Doubled Triangular Pulse Signal Generation with Variable Symmetry Based on a Dual-Polarization Quadrature Phase-Shift Keying Modulator

Frequency-Doubled Triangular Pulse Signal Generation with Variable Symmetry Based on a Dual-Polarization Quadrature Phase-Shift Keying Modulator

ФОРМИРОВАНИЕ ОДНОПОЛОСНОЙ КВАДРАТУРНОЙ ФАЗОВОЙ МАНИПУЛЯЦИИ РАДИОСИГНАЛОВ НА ПОДНЕСУЩИХ ЧАСТОТАХ В КОГЕРЕНТНОЙ ОПТИЧЕСКОЙ СИСТЕМЕ КОММУНИКАЦИИ

The coherent optical communication technology allows to create a transmission system overlong distances with high bandwidth. Higher order modulation formats such as Quadrature PhaseShift Keying (QPSK) provide high data rates in a simple, reliable and cost-effective manner. Thesemulti-bit modulation methods are transmitted as a symbol implementing simple in-phase andquadrature (IQ) modulation formats. To increase throughput in coherent optical systems, opticalsubcarrier multiplexing is used, when several radio signals are multiplexed on one optical carrier.This multiplexing is limited by double sideband, resulting in reduced received subcarrier powerand degraded carrier-to-noise ratio. To accumulate these effects, many ways of implementingoptical single sideband (OSSB) are proposed. The paper proposes an analysis of a coherent opticaltransmission system for generating single-sideband QPSK modulation using an optical I/Qmodulator and M-ary RF pulse shaping. The pseudo-random bit sequence generator generates a10 Gb/s modulation baseband signal. Each bit sequence is converted into an M-ary sequence ofsymbols from binary signals using phase shift keying (PSK). The M-ary pulse generator generatesa multi-level pulse shaping according to the sequence of M-ary input symbols. Electrical pulsesare applied to the electrodes of the electro-optical modulator according to the Mach–Zehnderinterferometer (MZM) scheme. The I/Q modulator operated at the quadrature operating point inboth the in-phase and quadrature branches, with an extinction ratio 60 dB and 3 V switching voltage.The light wave is emitted by a CW laser with a wavelength of 1550 nm.

Distortion Analysis of RF Power Amplifier Using Probability Density of Input Signal and AM-AM Characteristics

When confirming the ACLR (adjacent channel leakage power ratio), which are representative indicators of distortion in the design of PA (power amplifier), it is well known how to calculate the AM-AM/PM characteristics of PA, input time series data of modulated signals, and analyze the output by Fourier analysis. In 5G (5th generation) mobile phones, not only QPSK (quadrature phase shift keying) modulation but also 16QAM (quadrature modulation), 64QAM, and 256QAM are becoming more multivalued as modulation signals. In addition, the modulation band may exceed 100MHz, and the amount of time series data increases, and the increase in calculation time becomes a problem. In order to shorten the calculation time, calculating the total amount of distortion generated by PA from the probability density of the modulation signal and the AM (amplitude modulation)-AM/PM (phase modulation) characteristics of PA is considered. For the AM-AM characteristics of PA, in this paper, IMD3 (inter modulation distortion 3) obtained from probability density and IMD3 by Fourier analysis, which are often used so long, are compared. As a result, it was confirmed that the result of probability density analysis is similar to that of Fourier analysis, when the nonlinearity is somewhat small. In addition, the agreement between the proposed method and the conventional method was confirmed with an error of about 2.0dB of ACLR using the modulation waves with a bandwidth of 5MHz, RB (resource block) being 25, and QPSK modulation.

A 4 × 210 Gbps high-speed optical wireless system in medium earth orbit (MEO) using matched filters and digital signal processing

Abstract In this work, a high-speed optical wireless system is realized to cater to the bandwidth demands of data services in inter-satellite by using 4 × 210 Gbps capacity enabled by dual-polarization (DP) 128-Quadrature amplitude modulation (QAM) at 25 GHz channel spacing and artificial intelligence (AI). For nonlinear compensation, equalization, normalization, and interference reduction, digital signal processing (DSP), and matched filters are included in the receiver. Results are analyzed by considering error vector magnitude (EVM), Q-factor, and BER at different link lengths. Moreover, two polarizations such as horizontal and vertical polarizations are investigated separately to find out optimal polarization state. Further comparison of the proposed DP-128 QAM is performed with quadrature phase-shift keying (QPSK)and results revealed that the QAM system carrying different states of polarization (SOPs) successfully covered 17,500 km at 125 Gbps and offered enhanced performance as compared to the conventional QPSK and QAM modulations due to narrow carrier spectrum (27 symbols).

Performance analysis of physical-layer network coding with QPSK modulation in wireless IoT networks

In this paper, we mathematically analyze bit-error rate (BER) and diversity order of physical-layer network coding (PNC) scheme in the two-way relay channel (TWRC) under the assumption of multiple antennas at relay node. We assume the quadrature phase shift keying (QPSK) modulation for simple data transmission in IoT applications, and max–min transmit antenna selection (TAS) scheme in the broadcast (BC) phase for achieving full diversity gain. In particular, we obtain the upper bound of BER at the multiple access (MA) phase, while deriving the exact BER performance at the BC phase. To the best our knowledge, the mathematical analysis in this paper is the first analytical results in the literature. Through computer simulations, the analytical results are validated.

Photonics-assisted joint communication-radar system based on a QPSK-sliced linearly frequency-modulated signal.

A photonics-assisted joint communication-radar system is proposed by introducing a quadrature phase-shift keying (QPSK)-sliced linearly frequency-modulated (LFM) signal. An LFM signal is carrier-suppressed single-sideband modulated onto the optical carrier in one dual-parallel Mach-Zehnder modulator (DPMZM) of a dual-polarization dual-parallel Mach-Zehnder modulator (DPol-DPMZM). The other DPMZM is biased as an IQ modulator to implement QPSK modulation on the optical carrier. The polarization orthogonal optical signals from the DPol-DPMZM are further combined and detected in a photodetector to generate the QPSK-sliced LFM signal. The QPSK-sliced LFM signal is used to realize efficient data transmission and high-performance radar functions including ranging and imaging. An experiment is performed. Radar range detection with an error of less than 4 cm, inverse synthetic aperture radar imaging with a resolution of 14.99cm×3.25cm, and communication with a data rate of 105.26 or 210.52 Mbit/s are successfully verified.

Reconfigurable photonics-based millimeter wave signal aggregation for non-orthogonal multiple access.

A reconfigurable optical-to-electrical signal aggregation is proposed, for the first time, using optical signal processing and photo-mixing technology. Two optically modulated quadrature phase-shift keying (QPSK) signals are aggregated into a single 16-quadrature amplitude modulation (16-QAM) signal and, simultaneously, carried over a 28-GHz millimeter wave (MMW) carrier using an optimized heterodyne beating process through a single photodiode. To demonstrate the system reconfigurability, aggregation of two optical binary phase-shift keying signals is mapped into MMW QPSK or four-level pulse amplitude modulation signals by controlling the relative phases and amplitudes, respectively, of the input signals. In addition, the aggregation of two 16-QAM signals into a 256-QAM signal and the aggregation of three QPSK signals into a 64-QAM format are achieved. Besides, we report the effect of laser phase noise on signal aggregation performance. The de-aggregation of the aggregated MMW signals is performed electrically using a successive interference cancellation algorithm. Moreover, a proof-of-concept experiment is conducted to validate the numerical simulations. Two 1-Gbaud BPSK (1 Gbps) and QPSK (2 Gbps) optical signals are optically transmitted over a 20-km single-mode fiber as MMW over fiber signals. Then, the signals are aggregated into QPSK (2 Gbps) and 16-QAM (4 Gbps) 28-GHz MMW signals, respectively. The aggregated signal is further transmitted over a 1-m wireless channel. The performance of the proposed system is evaluated using bit error rate and error vector magnitude metrics.

Photonic Generation and Antidispersion Transmission of Background-Free Multiband Arbitrarily Phase-Coded Microwave Signals

A novel type of photonic background-free multiband arbitrarily phase-coded microwave signal generator with power fading elimination capability is reported. An <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x$ </tex-math></inline-formula> -polarized phase modulated optical signal and a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$y$ </tex-math></inline-formula> -polarized radio frequency (RF) modulated harmonic single-sideband (HSSB) optical signal are produced based on a dual-polarization quadrature phase shift-keying modulator (DP-QPSKM). After polarization modulation to intensity modulation conversion, a microwave signal with arbitrarily phase encoding in multiple frequency bands is generated. Benefiting from the phase modulation state of the driven electrical coded signal, the generated arbitrarily phase-coded signal has no baseband components. Moreover, the equivalent HSSB modulation ensures the system can realize antidispersion transmission of one-to-multi base stations (BSs). The main distinct highlights of our generator are multifunction. The proposed single-modulator-based photonic scheme can achieve phase encoding in arbitrary format over multiple frequency bands and transmit over long-distance single-mode fiber with the elimination of power fading simultaneously. This work is pretty promising in multiband radar systems for one-to-multi BSs transmission and can increase the detection range, range resolution, Doppler tolerance, and sensitivity of objective recognition of radars.

Comparative analysis of underwater wireless optical communication system

The performance of an underwater wireless optical communication (UWOC) system is affected by many factors, such as channel conditions, modulation and detection techniques, type of optical source, etc. The UWOC system performance was investigated in the presence of weak and strong turbulence. Pure sea was the water type used for the performance analysis. Binary phase shift keying, quadrature phase shift keying (QPSK), 16-quadrature amplitude modulation, and non-return to zero-on–off keying were used for comparison. Further, a continuous wave laser was used as the optical source, and photodetectors are at the receiver. The performance of the UWOC system was analyzed in terms of the bit error rate (BER). The BER performance was evaluated using the log-normal probability density function (PDF) in weak turbulence and the gamma-gamma PDF in strong turbulence. In all modulation techniques, QPSK had the best BER performance. The BER was reduced further using avalanche photodiode (APD) as the photodetector instead of positive-intrinsic-negative diode for the same transmitter power and channel conditions. In weak turbulence, a BER of 10 − 8 was achieved at a transmitter power of 12.5 dBm using the QPSK modulation technique and APD as the photodetector. For the same conditions, a BER of 9 × 10 − 7 was achieved in strong turbulence. The multiplication gain, dark current, and carrier ionisation ratio of the photodetector were optimized for better BER performance in the UWOC system.

Robust interference cancellation for differential quadrature phase-shift keying modulation with band limiting and adaptive filter

Differential quadrature phase-shift keying (DQPSK) modulation techniques and their variants are widely applied in digital communication, such as for high-speed optical fiber, bluetooth, or satellite communication. In its implementation, DQPSK cannot be separated from the potential harmful interference. In this research, a system model has been made for observation and analysis of the interference cancellation process. Discrete finite-duration impulse response (FIR) filters for band limiting and adaptive filter are the key components of the supporting block for this system model. Robust Simulink results have shown a significant increase in system performance in the existence of these key components. The indication has been shown by the best bit error rate (BER) of 3.3e-05. Constellation and eye pattern diagrams have supported the BER.

Adaptive filter and pulse-shaping for interference cancellation of differential quadrature phase-shift keying modulation

Differential quadrature phase-shift keying (DQPSK) modulation methods and variations are commonly used in wireless communication, including high-speed optical fiber, Bluetooth, and satellite communication. DQPSK cannot be isolated from possible interference with its present application. The interference cancellation process has been observed and analyzed using a device model built in this study. The core components of the supporting block for this device model have raised cosine filters for pulse shaping and adaptive filters. The presence of these core components has resulted in a dramatic improvement in device efficiency, according to robust Simulink data. The best bit error rate (BER) of 5.7e-03 provides evidence of this.

Graphene-based BPSK and QPSK modulators working at a very high bit rate (up Tbps range)

We are presenting graphene-based Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK) modulators, which can operate in the range from the TeraHertz up to the infrared. It is noteworthy that these devices have huge advantages over the silicon Mach–Zehnder optical modulators (MZMs) with lateral PN-junction rib-waveguide phase shifters. Among the countless advantages, we can mention, for example, that these modulators consist of only one waveguide and have a much simpler application system of the modulator signal (gate voltage) than in silicon-based MZMs. Other huge advantages are greater efficiency, and yet, they are cheaper and have shorter lengths [and consequently, greater integration in photonic integrated circuit (PIC)]. The first step to present these modulators was to detail the graphene theory that is involved in this device. After this step, we show the project, numerical simulations, and analyses related to our graphene-based BPSK and QPSK modulators. We believe that these modulators will contribute to the generation of new devices made up of 2D materials, which should revolutionize this area of science.