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Burst-Mode Synchronization for SOQPSK
摘要： We consider a comprehensive synchronization strategy for burst-mode transmission of shaped-offset quadrature phase-shift keying (SOQPSK) signals over the additive white Gaussian noise (AWGN) channel. Due to the similarities between SOQPSK and continuous phase modulation (CPM), we make use of recent results for synchronization of burst-mode CPMs. We first derive a training sequence that is optimal in the sense that it jointly minimizes the Cramér–Rao bounds (CRBs) for frequency offset, phase offset, and timing offset estimation. Additionally, we develop a maximum likelihood (ML) data-aided (DA) algorithm for joint estimation of the synchronization parameters for SOQPSK signals. We show that the proposed algorithm for the optimal training sequence can be adapted to work with the suboptimal training sequence that is being considered for use in burst-mode network enhanced telemetry (iNET). This demonstrates an immediate practical application for our approach. We present numerical results on the mean-squared error (MSE) performance of the proposed algorithm for both training sequences and for different versions of SOQPSK. The numerical results show that our joint estimation algorithm yields performance that is very close to the CRBs for all three synchronization variables. Finally, we compare the overall performance of our proposed training sequence and synchronization algorithm for different sequence lengths by simulating a burst-mode SOQPSK receiver. This allows us to employ the right training sequence length based on the desired complexity and bit error rate (BER) performance.
关键词： Shaped-offset quadrature phase-shift keying (SOQPSK),synchronization,phase offset,timing offset,frequency offset,burst-mode transmission
更新于2025-09-19 17:15:36
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - An Improved FPGA Parallel Design of Frequency Offset Estimation
摘要： In coherent optical communication QPSK system, an improved FPGA parallel design of frequency offset estimation with low complexity is proposed. The BER simulation results compared with serial scheme verify the feasibility of the parallel design.
关键词： coherent optical communication,QPSK,parallel design,low complexity,FPGA,frequency offset estimation
更新于2025-09-16 10:30:52
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Carrier Frequency Offset Estimation for BPSK Signals in Coherent Optical Communications
摘要： In this paper, a algorithm which is used for carrier frequency offset (CFO) estimation is proposed in coherent optical communications system with binary phase-shift keying (BPSK) modulation. The proposed algorithm utilizes the frequency divider to broaden the range of the estimation algorithm. In a 5-GBaud coherent BPSK system, simulation results show that when 12dB signal-to-noise ratio (SNR) and 512 samples are utilized, a 8 frequency divider can expand the range of the frequency offset estimation from [-0.5GHz, +0.5GHz] to [-4GHz, +4GHz] and the CFO estimation error can be obtained less than 5MHz. The paper presents a novel algorithm that features the large estimation range for carrier frequency offset while estimation error is not enlarged. The experimental results verified the effectiveness of the proposed algorithm.
关键词： costas optical phase-locked loop,BPSK modulation,carrier frequency offset estimation,frequency divider,Coherent optical communication
更新于2025-09-12 10:27:22
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Blind Carrier Frequency Offset Estimation in Coherent Optical Communication Systems with Probabilistically Shaped M-QAM
摘要： We find that the conventional 4th power and circular harmonic expansion (CHE) algorithms, which are originally devised for blind frequency offset estimation (FOE) in the uniform M-quadrature amplitude modulation (MQAM) systems, cannot work properly for probabilistically shaped (PS)-MQAM under moderate or strong shaping. To solve this issue, two novel blind FOE algorithms, namely the radius directed (RD)-4th power algorithm and the generalized circular harmonic expansion (GCHE) algorithm, are proposed. The former one adopts QPSK-selection based on a radius threshold optimized for a specific constellation entropy; while the later one conducts maximum likelihood (ML) estimation with a theoretically derived nonlinear radius transfer function in the GCHE.
关键词： Carrier frequency offset estimation,coherent optical communication,probabilistically shaped (PS) M-quadrature amplitude modulation (MQAM)
更新于2025-09-11 14:15:04
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[IEEE 2019 14th IEEE Conference on Industrial Electronics and Applications (ICIEA) - Xi'an, China (2019.6.19-2019.6.21)] 2019 14th IEEE Conference on Industrial Electronics and Applications (ICIEA) - Channel Tracking and Hybrid Energy Beamforming for WPT Enabled IoT System with Mobile mMIMO BS
摘要： In this paper, we consider the channel tracking and energy hybrid beamforming for the wireless power transfer (WPT) enabled Internet of Things (IoT) system, where the mobile base station (MBS) serves a set of half-duplex (HD) sensors that are uniformly distributed within its coverage area. A linear Kalman filter based multipath channel tracking and hybrid energy beamforming scheme is proposed by investigating the temporal and spatial properties of channel. Firstly, the Doppler frequency offset (DFO) is compensated through beam alignment and capturing the precise angular information from signals. Then, the multipath channel is tracked during the angle of arrival time (AOAT). Finally, the hybrid beamforming is applied to realize downlink WPT and uplink data transmission. The superiority of the proposed scheme is evaluated through simulations.
关键词： angle of arrival time (AOAT),mobile base station (MBS),wireless power transfer (WPT),hybrid energy beamforming,Kalman filter,Internet of Things (IoT),Channel tracking,Doppler frequency offset (DFO)
更新于2025-09-11 14:15:04
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Impact of the Coulomb Potential and the Electrostatic Potential on the Eigen-Frequencies of the Coupled Plasmons
摘要： In this paper, a coupled oscillator model is employed to describe the eigen-frequencies of the coupled plasmons, which are dominated by the coupled coefficient and the frequency offset defined by us. From this, we present a novel physical model to describe the influence of the Coulomb potential and the electrostatic potential (CPEP) on the coupled coefficient and the frequency offset. Based on the finite element method, we simulate numerically the evolution of the absorption spectra of the microstructure unit composed of a simply metal nanostructure. The simulated results show that two resonant absorption peaks are asymmetrical with the change of the coupling distance between the nano-elements. With the CPEP model, we not only explain successfully the asymmetrical behaviors of the peaks values of the absorption spectra with the change of the coupling distance but also obtain the resonant frequencies for different plasmons. The absorption spectra are simulated by the harmonic oscillator model, in which their calculated parameters originate from the CPEP model, and the results are very well association with those of the numerical simulation.
关键词： Eigen-frequencies,Harmonic oscillator model,Frequency offset,Coulomb potential and electrostatic potential
更新于2025-09-11 14:15:04
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Symbol Error Probability Analysis of DFrFT-based OFDM Systems with CFO and STO in Frequency Selective Rayleigh Fading Channels
摘要： In this article we derive exact symbol error probability (SEP) expressions for orthogonal frequency-division multiplexing (OFDM) based on discrete fractional Fourier transform (DFrFT) when symbol timing offset (STO) and carrier frequency offset (CFO) are present together. Closed form expressions are derived for binary phase shift keying, quadrature phase shift keying, and 16-ary quadrature amplitude modulation in the case of transmission over a frequency selective Rayleigh fading channel. As is well known, in OFDM the presence of CFO destroys the orthogonality between the sub-carriers, generating inter-carrier interference (ICI), while the presence of STO introduces intersymbol interference, between successive symbols, and phase rotations in frequency domain, within the same symbol. It is well recognized that an OFDM system based on DFrFT is more robust to ICI introduced by CFO than that based on discrete Fourier transform (DFT). Motivated by this, the combined effect of CFO and STO on the SEP of a DFrFT-based OFDM system is analyzed. Our results show that the DFrFT-based OFDM system outperforms that based on the DFT for different values of the DFrFT ‘angle parameter’. Monte Carlo simulations are used to demonstrate the correctness of the derived analytical expressions.
关键词： sampling-type FrFT,frequency selective fading,carrier frequency offset.,orthogonal frequency-division multiplexing (OFDM),Error rate analysis,symbol timing offset
更新于2025-09-10 09:29:36