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Shu Feng

Publications and source records attributed to Shu Feng.

3 recordsLinked to original sources

Super-Resolution Coherent Diffractive Imaging via Titled-Incidence Multi-Rotation-Angle Fusion Ptychography

Coherent diffractive imaging (CDI) enables lensless imaging with experimental simplicity and a flexible field of view, yet its resolution is fundamentally constrained by the Abbe diffraction limit. To overcome this limitation, we introduce a novel Tilted-Incidence Multi-Rotation-Angle Fusion Ptychography technique. This approach leverages a tilted-incidence geometry to extend the collection angle beyond the Abbe limit, achieving up to a -fold resolution enhancement. By acquiring diffraction patterns at multiple sample rotation angles, we capture complementary spatial frequency information. A tilted-incidence multi-rotation-angle fusion ptychographic iterative engine (tmf-PIE) algorithm is then employed to integrate these datasets, enabling super-resolution image reconstruction. Additionally, this method mitigates the anisotropic resolution artifacts inherent to tilted CDI geometries. Our technique represents a novel advancement in super-resolution imaging, providing a novel alternative alongside established methods such as STED, SIM, and SMLM.

physics.optics

Probability density derivation and analysis of SINR in massive MIMO systems with MF beamformer

In massive MIMO systems, the matched filter (MF) beamforming is attractive technique due to its extremely low complexity of implementation compared to those high-complexity decomposition-based beamforming techniques such as zero-forcing, and minimum mean square error. A specific problem in applying these techniques is how to qualify and quantify the relationship between the transmitted signal, channel noise and interference. This paper presents detailed procedure of deriving an approximate formula for probability density function (PDF) of the signal-to-interference-and-noise ratio (SINR) at user terminal when multiple antennas and MF beamformer are used at the base station. It is shown how the derived density function of SINR can be used to calculate the symbol error rate of massive MIMO downlink. It is confirmed by simulation that the derived approximate expression for PDF is consistent with the simulated PDF in medium-scale and large-scale MIMO systems.

cs.NI

A Frequency-domain Compensation Scheme for IQ-Imbalance in OFDM Receivers

A pilot pattern across two OFDM symbols with special structure is devised for channel estimation in OFDM systems with IQ imbalance at receiver. Based on this pilot pattern, a high-efficiency time-domain (TD) least square (LS) channel estimator is proposed to significantly suppress channel noise by a factor N/(L+1) in comparison with the frequency-domain LS one in [1] where N and L+1 are the total number of subcarriers and the length of cyclic prefix, respectively. Following this, a low-complexity frequency-domain (FD) Gaussian elimination (GE) equalizer is proposed to eliminate IQ distortion by using only 2N complex multiplications per OFDM symbol. From simulation, the proposed scheme TD-LS/FD-GE using only two pilot OFDM symbols achieves the same bit error rate (BER) performance under ideal channel knowledge and no IQ imbalances at low and medium signal-to-noise ratio (SNR) regions whereas these compensation schemes including FD-LS/Post-FFT LS, FD-LS/Pre-FFT Corr, and SPP/Pre-FFT Corr in [1] require about twenty OFDM training symbols to reach the same performance where A/B denotes compensation scheme with A being channel estimator and B being equalizer.

cs.NI