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Photonic Generation of a Windowed phase-Coded Microwave Waveform With Suppressed Spectrum Sidelobes

JOURNAL OF LIGHTWAVE TECHNOLOGY 2022年第20期40卷 6813-6822页

作者： Hu, Yang Chan, Erwin H. W. Wang, Xudong Feng, Xinhuan Guan, Bai-Ou Yao, Jianping Jinan Univ Inst Photon Technol Guangdong Prov Key Lab Opt Fiber Sensing & Commun Guangzhou 510632 Peoples R China Charles Darwin Univ Coll Engn IT & Environm Darwin NT 0909 Australia Univ Ottawa Sch Elect Engn & Comp Sci Microwave Photon Res Lab Ottawa ON K1N 6N5 Canada

An approach to photonic generation of a windowed binary phase-coded microwave waveform with suppressed spectrum sidelobes is proposed and demonstrated. An optical double sideband plus carrier signal with the carrier and the two sidebands being orthogonally polarized is generated by a dual-polarization quadrature phase shift keying (DP-QPSK) modulator, with the generated signal sent to a phase modulator (PM) where phase coding is performed. The PM can support phase modulation in two orthogonal polarization directions. The phase-modulated signals are projected to one polarization direction and detected at a photodetector (PD). Switching the polarity of the coding signal, a pi phase shift is introduced. Since the amplitude of the generated signal is dependent on the amplitude of the input coding signal, a windowing function is applied to the generated waveform by using a windowed input phase coding signal, to suppress the sidelobes in the spectrum of the generated microwave waveform. The key features of the proposed waveform generator include all-optical generation without the need of electronic components and optical filters, thus ensuring a wide operating frequency range. The proposed phase-coded microwave waveform generator also has the ability to switch between the fundamental and harmonic carrier frequency by controlling the modulator bias voltages. Experimental results show that, using a windowed 64-bit Gaussian pseudo-random binary sequence coding signal, a phase-coded microwave waveform is generated with the sidelobes of the spectrum largely suppressed by 20 dB and a pulse compression ratio as large as 133. Generation of binary phase-coded microwave waveforms at the 2nd harmonic carrier frequencies is also demonstrated experimentally.

关键词： Radio frequency Microwave photonics Microwave theory and techniques Encoding Microwave filters Microwave communication phase shift keying Frequency multiplication microwave photonics phase coding photonic signal generation pulse compression

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Modified codewords design for space-time block coded spatial modulation

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IET COMMUNICATIONS 2017年第2期11卷 249-257页

作者： Hua, Yuhao Zhao, Guannan Zhao, Wenjing Jin, Minglu Dalian Univ Technol Sch Informat & Commun Engn 2 Linggong Rd Dalian Peoples R China Liaoning Normal Univ Sch Phys & Elect Technol 850 Huanghe Rd Dalian Peoples R China

Two kinds of modified codewords for space-time block coded spatial modulation (STBC-SM) are presented in this study. The first modified codeword introduces a concept of flexible coefficients into the M-ary phase shift keying STBC-SM. A method is proposed to obtain the optimal flexible coefficients. Moreover, the first modified codewords can also be applied to the systems developed from the STBC-SM. In the second provided codewords, super-orthogonal space-time trellis codes are applied in STBC-SM. Therefore, a higher spectral efficiency is obtained compared with the original STBC-SM. Finally, the simulation results and theoretical analysis demonstrate these performance advantages of the two kinds of modified codewords for STBC-SM.

关键词： space-time block codes phase shift keying phase coding orthogonal codes trellis coded modulation spectral efficiency super-orthogonal space-time trellis code STBC-SM M-ary phase shift keying space-time block coded spatial modulation modified codeword design

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Multi-phase initial ranging process for OFDMA systems: improved dynamic threshold-based multi-user detection approach

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IET COMMUNICATIONS 2020年第13期14卷 2130-2140页

作者： Naveen, Kolihalli Narasaiah Ramesha, Kenchappa Dr Ambedkar Inst Technol Dept Elect & Commun Engn Bengaluru Karnataka India Dr Ambedkar Inst Technol Dept Elect & Instrumentat Engn Bengaluru Karnataka India

Initial ranging (IR) is a process of performing power adjustment, timing offset estimation, and synchronisation between the base station (BS) and all users. It plays a vital role in mobile WiMAX standard, which establishes a communication link between BS and ranging subscriber stations (RSSs). Since RSS is located far away from the BS and uplink signal is corrupted by noise, the IR process becomes inferior. Thus, the authors propose an improved dynamic threshold-based IR method comprising three phases: (i) code detection phase, (ii) filtering phase, and (iii) parameter estimation phase. In the first two phases, the received signal is pre-processed to eliminate noise and unselected codes from the codeset by employing adaptive filter and weight-based code detection method. Then, the noise-free signal is considered for the final phase, which improves accuracy. The iterative expectation maximisation algorithm is involved in the estimation of channel coefficient and timing offset. All possible active paths are detected by setting a dynamic threshold value for each channel by the enhanced dynamic threshold method. For all active channels, round trip delay, and power level are estimated by considering particular channel coefficient and timing offset. Extensive simulation of proposed work shows considerable improvements in performance.

关键词： multiuser detection frequency division multiple access adaptive filters expectation-maximisation algorithm OFDM modulation parameter estimation phase coding signal denoising channel estimation OFDMA systems base station mobile WiMAX standard ranging subscriber stations filtering phase parameter estimation phase received signal noise-free signal weight-based code detection method enhanced dynamic threshold method channel coefficient unselected code detection phase multiphase initial ranging process RSS timing offset estimation synchronisation communication link iterative expectation maximisation algorithm dynamic threshold-based IR method dynamic threshold-based multiuser detection approach

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Design and analysis of a spread-spectrum communication system with chaos-based variation of both phase-coded carrier and spreading factor

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IET COMMUNICATIONS 2015年第12期9卷 1466-1473页

作者： Quyen, Nguyen Xuan Van Yem, Vu Duong, Trung Q. Hanoi Univ Sci & Technol Sch Elect & Telecommun Hanoi Vietnam Queens Univ Belfast Belfast Antrim North Ireland Duy Tan Univ Da Nang Vietnam

This study designs and analyses a new phase-coded spread-spectrum communication system where both phase-coded carrier and spreading factor are varied based on a chaotic behaviour in the communication process. This design aims to reduce the probability of interception of the considered system. Discrete values generated by a chaotic map are exploited to create a non-return-to-zero (NRZ)-chaos sequence and simultaneously make bit duration variable. The NRZ-chaos sequence is then modulated by binary phase-shift keying technique to produce the phased-coded carrier. Owing to chip duration being constant, the variation of bit duration also leads to the variation of spreading factor. Spectrum spreading in the transmitter is performed by multiplying directly the variable-duration bits with the phase-coded carrier. A coherent receiver relying on a direct correlator is used for recovering the data. Design of the transmitter and receiver as well as analysis of bit error probability for the proposed system in cases of single-user and multi-user under additive white Gaussian noise channel is presented. Simulation results are shown to confirm the operation of the designed structures and the obtained analytical performance.

关键词： spread spectrum communication phase coding error statistics Gaussian channels spread spectrum communication system chaos based variation phase coded carrier spreading factor phase coded spread spectrum communication system chaotic behaviour communication process discrete values chaotic map non-return-to-zero NRZ chaos sequence binary phase shift keying technique phased coded carrier chip duration bit duration variation spectrum spreading direct correlator bit error probability Gaussian noise channel

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Optimal design of anti-interrupted sampling repeater jamming waveform for missile-borne radar based on an improved genetic algorithm

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IET SIGNAL PROCESSING 2021年第9期15卷 622-632页

作者： Cao, Fei Chen, Zi-han Feng, Xiao-wei He, Chuan Xu, Jian-feng PLA Rocket Force Univ Engn Xian 710025 Peoples R China

The optimal design of transmitted waveforms to improve the performance of missile-borne radar in suppressing interrupted sampling repeater jamming (ISRJ) is studied here. The waveform diversity property requires that the waveform group has excellent orthogonality (good auto- and cross-correlation properties), which is an effective waveform optimisation design method for missile-borne radar electronic counter-countermeasures. The principle of orthogonal phase coding waveform against ISRJ is studied and the use of chaotic sequences is proposed to initialise the population, as well as a simulated annealing selection operator, which improves the convergence speed of the improved genetic algorithm (IGA) and enhances the global optimisation ability. The IGA improves the shortcomings of GA, that is, easily falling into a local optimum and slow search speed, and can realise a global search for longer orthogonal polyphase coding sequence sets. The simulation examples demonstrate the good jamming suppression performance of the proposed method.

关键词： electronic countermeasures genetic algorithms jamming missiles optimisation phase coding radar signal processing search problems simulated annealing

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ON THE PERFORMANCE OF A HYBRID FREQUENCY AND phase-SHIFT KEYING MODULATION TECHNIQUE

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IEEE TRANSACTIONS ON COMMUNICATIONS 1993年第5期41卷 655-659页

作者： KHALONA, RA ATKIN, GE LOCICERO, JL IIT DEPT ELECT & COMP ENGN CHICAGO IL 60616 USA

In this paper, we present the performance of a hybrid modulation technique derived from binary frequency shift keying. In the hybrid scheme, each frequency is allowed to be phase modulated with any of p discrete, equally spaced phase shifts. The spectral separation between frequencies, DELTAf, is chosen to make the carriers orthogonal, thus generating a multi-dimensional modulation scheme. The performance of complete and expurgated phase codes is examined for the Gaussian and Rayleigh fading channels, and their spectral characteristics are determined.

关键词： Raleigh fading channels phase shift hybrid modulation Gauss binary frequency shift keying spectral characteristic spectral separation phase coding

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Photonic generation of phase-coded millimeter-wave signal using a polarization modulator

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IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS 2008年第5期18卷 371-373页

作者： Chi, Hao Yao, Jianping Zhejiang Univ Dept Informat & Elect Engn Hangzhou 310027 Peoples R China Univ Ottawa Microwave Photon Res Lab Sch Informat Technol & Engn Ottawa ON K1N 6N5 Canada

A novel approach to generating phase-coded millimeter-wave (mm-wave) signal in the optical domain is proposed. In the proposed system, a radio frequency signal is applied to a Mach-Zehnder modulator that is biased at the minimum transmission point to generate two optical sidebands with suppressed carrier. A differential group delay device is utilized to rotate the polarization states of the optical sidebands to ensure they are orthogonally polarized. The two sidebands are then sent to a polarization modulator (PoIM), with their polarization directions aligned with the two principal axes of the PoIM, to achieve phase coding. A 33-GHz mm-wave signal that is phase coded by an 8.28 Gb/s digital sequence is experimentally demonstrated. The approach has potential applications in mm-wave pulse compression radar and wireless communications.

关键词： millimeter-wave (mm-wave) signal generation phase coding phase modulation pulse compressed radar

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Optimal Code Set Selection and Security Issues in Spectral phase-Encoded Time Spreading (SPECTS) OCDMA Systems

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2012年第12期30卷 1882-1890页

作者： Bertarini, Pedro L. L. Sanches, Anderson L. Borges, Ben-Hur V. Univ Sao Paulo Dept Elect Engn Sao Carlos Sch Engn BR-13566590 Sao Carlos SP Brazil

In this paper, we perform a thorough analysis of a spectral phase-encoded time spreading optical code division multiple access (SPECTS-OCDMA) system based on Walsh-Hadamard (W-H) codes aiming not only at finding optimal code-set selections but also at assessing its loss of security due to crosstalk. We prove that an inadequate choice of codes can make the crosstalk between active users to become large enough so as to cause the data from the user of interest to be detected by other user. The proposed algorithm for code optimization targets code sets that produce minimum bit error rate (BER) among all codes for a specific number of simultaneous users. This methodology allows us to find optimal code sets for any OCDMA system, regardless the code family used and the number of active users. This procedure is crucial for circumventing the unexpected lack of security due to crosstalk. We also show that a SPECTS-OCDMA system based on W-H 32(64) fundamentally limits the number of simultaneous users to 4(8) with no security violation due to crosstalk. More importantly, we prove that only a small fraction of the available code sets is actually immune to crosstalk with acceptable BER (<10(-9)) i.e., approximately 0.5% for W-H 32 with four simultaneous users, and about 1 x 10(-4)% for W-H 64 with eight simultaneous users.

关键词： Optical code division multiple access optical fiber communications multiple access interference (MAI) phase coding

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Simultaneous Multi-Frequency phase-Coded Microwave Signal Generation at Six Different Frequencies Using a DP-BPSK Modulator

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2019年第10期37卷 2293-2299页

作者： Chen, Yang Yao, Jianping East China Normal Univ Shanghai Key Lab Multidimens Informat Proc Shanghai 200241 Peoples R China Univ Ottawa Sch Elect Engn & Comp Sci Microwave Photon Res Lab Ottawa ON K1N 6N5 Canada

An approach to the generation of a multi-frequency phase-coded microwave signal at six different microwave carrier frequencies using a laser diode and a dual-polarization binary phase-shift keying (DP-BPSK) modulator is proposed and experimentally demonstrated. The key component in the proposed system is the DP-BPSK modulator, which consists of two dual-drive Mach-Zehnder modulators (DD-MZMs) that are driven by a binary coding signal and a microwave reference signal. By controlling the bias points of the DD-MZMs, and the power of the coding signal and the microwave reference signal, phase-coded microwave signals at six different frequencies are generated at the output of a photodetector. An experiment is performed. A multi-frequency phase-coded microwave signal at six different carrier frequencies in a frequency range from 1 to 19.5 GHz is generated. The performance in terms of phase recovery accuracy and pulse compression capability is evaluated. The interferences between different channels are also evaluated and no significant interferences are observed.

关键词： Microwave photonics multiband radar phase coding photonic signal generation pulse compression

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Successive QCQP Refinement for MIMO Radar Waveform Design Under Practical Constraints

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2016年第14期64卷 3760-3774页

作者： Aldayel, Omar Monga, Vishal Rangaswamy, Muralidhar Penn State Univ Dept Elect Engn University Pk PA 16802 USA US Air Force Res Lab RF Exploitat Branch Dayton OH USA

The authors address the problem of designing a waveform for multiple-input multiple-output (MIMO) radar under the important practical constraints of constant modulus and waveform similarity. Incorporating these constraints in an analytically tractable manner is a longstanding open challenge. This is due to the fact that the optimization problem that results from signal-to-interference-plus-noise ratio (SINR) maximization subject to these constraints is a hard non-convex problem. The authors develop a new analytical approach that involves solving a sequence of convex quadratically constrained quadratic programing (QCQP) problems, which they prove converges to a sub-optimal solution. Because an improvement in SINR results via solving each problem in the sequence, they call the method Successive QCQP Refinement (SQR). Furthermore, the proposed SQR method can be easily extended to incorporate emerging requirements of spectral coexistence, as shown briefly in this paper. The authors evaluate SQR against other candidate techniques with respect to SINR performance, beam pattern, and pulse compression properties in a variety of scenarios. Results show that SQR outperforms state-of-the-art methods that also employ constant modulus and/or similarity constraints while being computationally less burdensome.

关键词： MIMO radar waveform design constant modulus similarity constraint successive algorithm phase coding SQR interference constraint cognitive radar

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