Quadrature Phase Shift Keying Modulation Research Articles

English

Binary phase shift keying (BPSK) and quadrature phase shift Keying (QPSK)modulation techniques are often proposed for satellite communications and band-limited communication channels; however, both modulations are important in high speed data communications. High speed data communications are implemented on high speed hardware in wireless systems. The paper presents the design of a QPSK and BPSK digital communication modulators and their implementations on high speed field-programmable gate array (FPGA) using Quartus II. Also, for these modulation schemes, resource utilization was introduced. Both modulations were designed in Quartus II using VHDL hardware description language. It was shown that transmission of QPSK modulator is fast than transmission of BPSK modulator at the same bit error performance. According to BPSK, QPSK modulator uses more memory. But other resources equal to for these modulation. Principles of the BPSK modulation and QPSK modulation are illustrated using schematic diagrams. The analysis of theoretical aspects of the BPSK and QPSK modulations are represented. Both modulations waveforms are illustrated using a simulation program. Implementations of the BPSK and QPSK systems on FPGA are shown using algorithms of modulator. Key words: Binary phase shift keying (BPSK), quadrature phase shift Keying (QPSK), field-programmable gate array (FPGA).

Shaped offset quadrature phase shift keying (SOQPSK) modulation scheme and its application in optical wavelength-division multiplexed (DWDM) transmission

This paper presents a new quaternary modulation scheme called SOQPSK. The principle on the optical SOQPSK generation is derived and analyzed, which is implemented by traditional Mach–Zehnder modulators. The performance of the optical SOQPSK modulated system is evaluated and compared with those of quadrature phase shift keying (QPSK) and offset QPSK (OQPSK) modulation systems via simulation, in terms of spectral efficiency, receiver sensitivity and density DWDM transmission performance. Simulations show that the novel modulation scheme improves spectral efficiency for DWDM transmission and provides better transmission performance than QPSK.

Study of QPSK Modulator and Demodulator in Wireless Communication System Using MATLAB

Quadrature Phase-Shift Keying (QPSK) modulation technique is one of the most widely used modulation scheme in modern digital communication system; it provides high performance on bandwidth efficiency. In this paper, the model of QPSK modulator and demodulator has been simulated using MATLAB Simulink.

Flexible high-order QAM transmitter using tandem IQ modulators for generating 16/32/36/64-QAM with balanced complexity in electronics and optics

In order to adapt to the dynamics in the future optical networks, we propose a flexible high-order QAM transmitter using a tandem in-phase/quadrature (IQ) modulators to synthesize different high-order quadrature amplitude modulation (QAM) formats, such as 16QAM, 32 or 36QAM and 64QAM. To generate high-order QAMs, an offset-QAM is firstly generated using an IQ modulator driven by electronics with reduced modulation-level, and then mapped to other quadrants through another following IQ modulator configured as a standard quadrature phase-shift keying (QPSK) modulator. All of the embedded sub-Mach-Zehnder modulators are operated in push-pull configurations to avoid introducing excess phase chirp. In contrast with the schemes based on a single IQ modulator driven by multilevel electronics or a highly-integrated parallel modulator, by deploying commercially-available optical modulators and driving electronics with reduced modulation-level, the transmitter complexity in optics and electronics is well-balanced. In the case of generating optical 64QAM, different from another tandem scheme deploying dual-drive IQ modulator driven by independent four binary streams, less phase chirp is observed in our proposed scheme, and comparable implementation penalty is obtained even without applying additional specific compensation algorithm in the coherent receiver. Moreover, thanks to the tandem structure and the deployment of QPSK modulator, the obtained high-order QAM is naturally differentially coded, which is helpful to solve the phase ambiguity at coherent receiver. We experimentally demonstrate the generations of these high-order QAMs including 16QAM, 32/36QAM and 64QAM, and confirm the error-free operations with comparable BER performance to the "electrical" approach based on a single IQ modulator.

Design and study of high bit-rate free-space optical communication system employing QPSK modulation

We have proposed Free–Space Optics systems (FSO), which are Diffused Link (DL) and Line–of–Sight (LOS) setup using Quadrature Phase Shift Keying (QPSK) technique. The optimized coverage distance, for an input power level of 5 dBm and data rate of 1 Gbps, is found to be 1036.307m and 2388.725km for DL and LOS setup respectively. Also, the proposed system is simulated for 1.25 Gbps, 2.5 Gbps, 10 Gbps, 40 Gbps and 100 Gbps with free–space attenuation of 200 dB/km using Optisystem 9.0 and Matlab 7.9.0. The system will be useful where the coverage area, performance, security and cost–savings are critical factors.

112-Gb/s monolithic PDM-QPSK modulator in silicon

We present a monolithic dual-polarization quadrature phase-shift keying (QPSK) modulator based on a silicon photonic integrated circuit (PIC). This PIC consists of four high-speed silicon modulators, a polarization rotator, and a polarization beam combiner. A 112-Gb/s polarization-division-multiplexed (PDM) QPSK modulation is successfully demonstrated.

Inter-satellite optical wireless communication system design and simulation

An ultra-high bit-rate inter-satellite optical wireless communication (IsOWC) system is proposed in thisstudy. The system is designed and simulated up to the bit-rate of 400 Gbps. The proposed system is a non-diffused link or line-of-sight setup, which uses coherent optical quadrature phase-shift keying (QPSK) modulation technique. The performance of the system is analysed in terms of Q -factor, bit-error rate, eye opening and so on. The coverage distance observed with an input power level of 30 dBm for a bit-rate of 400, 160 and 100 Gbps are 4767, 7542 and 9532 km, respectively. Finally, the maximum bit-rate that can be communicated, for inter-satellite link at different orbits such as low-Earth orbit, medium-Earth orbit and geostationary Earth orbit are presented. To the best of the authors knowledge for the first time they have proposed a novel QPSK modulation technique for the design of IsOWC system for achieving higher coverage distance and data rate, which was not been addressed in any current or earlier publications.

All-Optical OOK to 16-QAM Modulation Format Conversion Employing Nonlinear Optical Loop Mirror

This paper proposes and numerically demonstrates an all-optical on-off keying (OOK) to 16 quadrature amplitude modulation (QAM) format conversion using nonlinear optical loop mirror (NOLM) based on cross-phase modulation (XPM) and parametric amplification in optical fibers. The 16-QAM signal is generated by the superposition of two quadrature phase shift keying (QPSK) signals with different amplitudes. OOK to QPSK modulation format conversion is achieved by XPM in one highly nonlinear fiber (HNLF). The amplitude ratio 2:1 of two QPSK signals can be realized by parametric amplification. The feasibility of OOK to 16-QAM modulation format conversion is confirmed at the symbol rate of 10 Gs/s by numerical simulation with the length of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$2^{7}-1$</tex></formula> pseudo random binary sequence (PRBS) input OOK signals. The tolerance of power deviation of the converter is also analytically evaluated.

저전력 수중음향통신을 위한 등화기에 관한 연구

이 논문에서는 저전력 수중음향통신을 위해 PSSK(Phase Silence Shift Keying) 기법이 적용되었을 때 심볼 간 간섭을 최소화하기 위한 등화기를 제안하였다. PSSK 방식은 QPSK(Quadrature Phase Shift Keying) 변조와 PPM(Pulse Position Modulation) 기법이 서로 혼합된 형태이며, 저전력 통신을 위해 제안된 기법이다. 하지만 이는 수중 채널의 지연 확산 특성으로 인해 성능이 저하되는 문제점을 갖고 있다. 이에 이 논문에서는 PSSK 수신단에서 오차를 최소화하기 위한 결정 궤환 등화기를 제안하였으며, 제안한 방법의 성능을 입증하기 위해 해상시험을 수행하였다. 실험 결과 등화기를 적용하지 않은 PSSK 전송의 경우는 오차율이 <TEX>$4.36{\times}10^{-2}$</TEX> 이었지만, 제안한 등화기를 적용한 경우 <TEX>$3.95{\times}10^{-4}$</TEX> 으로 나타났다. In this paper, we propose an equalizer to minimize the inter-symbol interference when PSSK(Phase Silence Shift Keying) technique is applied to the low power underwater acoustic communication. PSSK is a QPSK(Quadrature Phase Shift Keying) modulation combined with PPM(Pulse Position Modulation), and it was proposed for low power communication. However, it has poor performance due to delay spread of underwater channel. In this paper, we propose a decision feedback equalizer to minimize the error in PSSK receiver. The sea trial was performed to evaluate the performance of the proposed method. In the result, the BER of PSSK was <TEX>$4.36{\times}10^{-2}$</TEX> before the equalizer was applied, but the BER of PSSK was <TEX>$3.95{\times}10^{-4}$</TEX> after the proposed equalizer was applied.

Auto Bias Control Technique Based on Asymmetric Bias Dithering for Optical QPSK Modulation

This paper describes a simple and highly sensitive auto bias control (ABC) technique based on asymmetric bias dithering for optical quadrature phase shift keying (QPSK) modulation and QPSK variants. Using our asymmetric bias dithering proposal, the required bandwidth of the ABC circuit is only dc ~ 2fd, where fd is the frequency of dithering, fd <; 1 kHz. Thus, the circuit can be constructed without using high-speed components, and bias control performance is not limited by the signal bit rate. In this paper, we detail the concept of asymmetric bias dithering. We describe experiments that confirm bias monitoring and ABC operation, using a 20-64 Gbit/s optical QPSK signal. Its typical penalty is 0.1 dB, and Q factor fluctuation is negligible over 6 h of operation.

Comparative Study of BPSK and QPSK for Wireless Networks over NS2

Modulation plays an important role in transmission of single from transmitter to receiver in all communication systems. But it is vital in wireless communication and a lot of communication features including (data rate, error rate, symbol rate, bandwidth etc) depends upon it. In NS2 wireless network simulation BPSK is used for digital encoding and modulation of data [1,2]. The BPSK method is used by wireless/phy object that is inherited by Modulation Class. In this paper QPSK is used in place of BPSK and analyzed in terms of data rate, error rate and power consumption in NS 2 simulation. Also the proposed code for QPSK modulation is given in this paper. General Terms BPSK (Binary Phase Shift Keying), QPSK (Quadrature phase shift keying), Nb (Spectral noise of a single bit), Eb (Bit Energy during transmission), Sb (bit state representation), Pb (Bit Error Rate), φ(t) (signal space).

Experimental demonstration of microring quadrature phase-shift keying modulators

Advanced optical modulation formats are a key technology to increase the capacity of optical communication networks. Mach-Zehnder modulators are typically used to generate various modulation formats. Here, we report the first experimental demonstration of quadrature phase-shift keying (QPSK) modulation using compact microring modulators. Generation of 20 Gb/s QPSK signals is demonstrated with 30 μm radius silicon ring modulators with drive voltages of ~6 V. These compact QPSK modulators may be used in miniature optical transponders for high-capacity optical data links.

Direct quadrature phase shift keying modulation using compact wideband six-port networks

In this study, the operation of a compact six-port network operating as a quadrature phase shift keying (QPSK) modulator with a wide operational bandwidth is presented. The modulation has been accomplished using two types of single-layer six-port networks. The first six-port network uses a novel architecture that is newly introduced herein for use as a QPSK modulator, and employs broadband components previously developed by the same authors. The second six-port network employs the same types of broadband components in a conventional six-port architecture for comparison. The performance of the modulator using both six-port networks is tested using agilent&apos;s advanced design system and its wideband operation is verified with measured results. It is shown that the proposed six-port modulator offers accurate QPSK symbol modulation at a symbol rate of 400 Msymbols/s across an octave bandwidth from 4.5 to 9 GHz (66% operational bandwidth).

Performance of Free Space Optical Communication System with BPSK and QPSK Modulation

---Free Space Optics is the technology which implies the line-of-sight link for the transfer of data between two distant points. The beam of light is used to provide optical connection that can transmit and receive data. The performance of the modulation techniquesBinary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK) are studied in the Nakagami channel and the Rician Channel. The QPSK modulation provides double data rate than the BPSK modulation technique. The certain impairments associated with the FSO system are also studied in this work. The effect of scintillation index and Free Space Path Loss (FSPL) are also considered in this work.

Ambiguity function and Cramér–Rao bounds for universal mobile telecommunications system-based passive coherent location systems

The concerns are with the calculation of monostatic and bistatic ambiguity function (AF) of a quadrature phase shift keying (QPSK) signal where the pulses are shaped with a root raised cosine (RRC) filter. The monostatic and bistatic modified Cramér–Rao lower bounds (MCRLBs) for the estimation of target range and velocity are also derived and analysed. The QPSK modulation is used in the downlink of a universal mobile telecommunications system (UMTS) base station, hence the results of our analysis provide a useful tool to asses the performance of a passive coherent location (PCL) system where the non-co-operative transmitter of opportunity is a UMTS base station. The actual growing coverage of UMTS signals on the international territory makes multistatic radar configuration feasible, therefore these results can also be exploited for the dynamical selection of the transmitter in a multistatic radar system where multiple UMTS base stations are used.

A 50-Mb/s CMOS QPSK/O-QPSK Transmitter Employing Injection Locking for Direct Modulation

A 50-Mb/s quadrature phase-shift keying (QPSK)/offset quadrature phase-shift keying (O-QPSK) transmitter suitable for biomedical high-quality imaging application is presented. Centered at 915 MHz, the phase modulation is achieved by directly modifying the self-resonant frequency of an LC voltage-controlled oscillator through capacitor bank switching. By eliminating many unnecessary building blocks in the conventional QPSK/O-QPSK transmitter, significant power and area savings are achieved. Implemented in 0.18- μm CMOS technology, it occupies an active core area of 0.28 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . With 305-MHz injection frequency and consuming 5.6 mW under 1.4-V supply, the transmitter achieves error vector magnitude (EVM) of 11.4%/5.97% for O-QPSK/QPSK modulation while delivering output power of -3 dBm at 50 Mb/s. By lowering the injection frequency to 101.67 MHz, it consumes 5.88 mW under the same supply voltages while delivering an output power of -3.3 dBm. The transmitter achieves measured EVM of 6.4% at 50 Mb/s under QPSK modulation.

Asymmetric dithering technique for bias condition monitoring in optical QPSK modulator

A simple and highly sensitive bias condition monitoring circuit is presented for optical quadrature phase shift keying (QPSK) modulators. The proposed asymmetric dithering technique is shown to be capable of monitoring three bias states simultaneously. The dithering penalty is shown to be less than 0.2 dB.

Performance Analysis of Serial and Parallel Six-Port Modulators

We have derived the transfer functions for two types of six-port quadrature phase-shift keying (QPSK) modulators and investigated their performances in terms of carrier leakage, Gray mapping, and conversion efficiencies. Our result shows that the carrier leakage is minimized when Gamma <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> = -Gamma <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> . In addition, our analysis reveals here that only the parallel six-port QPSK modulator demonstrates a Gray mapping feature. Our analysis further proves that the serial and parallel modulator give a maximum conversion efficiency of 100% and 50%, respectively, but the efficiency of the serial modulator deteriorates faster than the parallel modulator when the terminations are not ideal. We have also shown that the serial modulator requires tighter design tolerances due to its cascaded topology. Our theoretical and measured results show good agreements with the six-port modulators developed for 4.2 GHz.

Symmetric Complex-Valued RBF Receiver for Multiple-Antenna-Aided Wireless Systems

A nonlinear beamforming assisted detector is proposed for multiple-antenna-aided wireless systems employing complex-valued quadrature phase shift-keying modulation. By exploiting the inherent symmetry of the optimal Bayesian detection solution, a novel complex-valued symmetric radial basis function (SRBF)-network-based detector is developed, which is capable of approaching the optimal Bayesian performance using channel-impaired training data. In the uplink case, adaptive nonlinear beamforming can be efficiently implemented by estimating the system's channel matrix based on the least squares channel estimate. Adaptive implementation of nonlinear beamforming in the downlink case by contrast is much more challenging, and we adopt a cluster-variation enhanced clustering algorithm to directly identify the SRBF center vectors required for realizing the optimal Bayesian detector. A simulation example is included to demonstrate the achievable performance improvement by the proposed adaptive nonlinear beamforming solution over the theoretical linear minimum bit error rate beamforming benchmark.

Performance comparison of low density parity check codes using square root Kalman equalisation and orthogonal frequency division multiplexing techniques for broadband fixed wireless access systems

Broadband fixed wireless access (BFWA) systems enable services such as high-speed data communication, high quality voice/video conferencing and high-speed internet access in areas where a wired link is not possible. However, the BFWA channel is a slow-fading channel having deep frequency-selective fading caused by clusters of scatterers in the environment that introduce inter-symbol interference (ISI) at the receiver. Low density parity check (LDPC) codes, optimised for the single-input single-output BFWA channel, are designed using the structured balance incomplete block design method. The use of both quadrature phase shift keying (QPSK) and 16-quadrature amplitude modulation (16-QAM) are investigated theoretically. To help overcome the ISI effects of the channel, equalisation techniques are employed separately with LDPC decoding for a system employing QPSK and 16-QAM modulation schemes. The equaliser single carrier approach is then replaced with orthogonal frequency division multiplexing (OFDM) and the performance of these two approaches is evaluated in terms of bit-error rate. The simulation results show that equalisation with LDPC coding has a measurable performance gain over LDPC coding with OFDM.