arXiv subjects

Chenbo Wang

Publications and source records attributed to Chenbo Wang.

6 recordsLinked to original sources

arXiv2026

FlashClear: Ultra-Fast Image Content Removal via Efficient Step Distillation and Feature Caching

Recently, diffusion-based object removal models have achieved impressive results in eliminating objects and their associated visual effects. However, they indiscriminately denoise all tokens across all timesteps, ignoring that removal usually involves small foreground regions. This strategy introduces substantial computational overhead and prolonged inference times. To overcome this computational burden, we propose a latent discriminator to implement Region-aware Adversarial Distillation (RAD), yielding a highly efficient few-step model named FlashClear. Furthermore, tailored to few-step diffusion models, we propose FPAC (Foreground-Prioritized Asymmetric Attention and Caching), a training-free acceleration strategy. Extensive experiments demonstrate that our framework provides massive acceleration while maintaining or exceeding the performance of our base model, ObjectClear. Notably, on the OBER benchmark, our FlashClear achieves up to 8.26$\times$ and 122$\times$ speedup over ObjectClear and OmniPaint, respectively, while maintaining high visual quality and fidelity.

cs.CV↗

arXiv2025

Challenging the Law of Energy Conservation Through Superposed Waves Based on Spatial Symmetry of Two RF Sources: Theoretical Derivation and Experimental Verification

This study is grounded in the concept of spatial symmetry, which allows two co-phase RF sources to jointly radiate harmonic electromagnetic (EM) waves, even in presence of electromagnetic couplings between them. The superposition law is directly applied to the two waves owing to their sources, including the EM coupling effects. Our research uncovers a conflict with energy conservation law at the following two levels: (1) the total radiative powers as defined by Poynting theorem, and (2) further, the input powers of the sources. To explore this phenomenon, we create a symmetric dipole model to examine the energy behaviors at the sources and the superposed waves, separately. Both of the results reveal that the energy-doubling phenomenon presents when the dipoles are placed in close proximity. As the distance between the two dipoles increases, it is found that the total radiative power fluctuates in a damped manner and ultimately converges to a value required by energy conservation law. The theoretical conclusion of energy doubling is validated by experimental observations, which show a 1.59-fold increase in power within a microwave anechoic chamber. By analyzing the interactions, i.e., the EM coupling, between the two sources, we characterize a complete phenomenon of energy non-conservation.

physics.class-ph↗

arXiv2024

Polarforming for Wireless Communications: Modeling and Performance Analysis

This paper presents, for the first time, the concept of polarforming for wireless communications. Polarforming refers to a novel technique that enables the polarization of an antenna to shape into a desired polarization state for aligning with the polarization of an electromagnetic (EM) wave. It can fully leverage polarization diversity to enhance the performance of wireless communication systems through polarization matching. To implement polarforming, we propose a new paradigm of phase shifter (PS)-based polarization-reconfigurable antennas (PRAs) that can form linear, circular, and general elliptical polarizations by phase shift control. To further demonstrate the benefits of polarforming, we investigate a PRA-aided wireless communication system equipped with tunable polarization of antennas. We characterize the multiple-input multiple-output (MIMO) channel capacity of the considered system as a function of the phase shifts of PS-based PRAs. We also provide a detailed polarforming interpretation under the single-input single-output (SISO) scenario and theoretically show how polarforming differs from the conventional (analog) beamforming based on PSs. Moreover, we develop an alternating optimization approach to maximize the channel capacity for the systems with single-antenna transmitter/receiver. Based on the water-filling principle, we also derive an upper bound on the MIMO channel capacity with PS-based PRAs and then maximize this capacity bound by optimizing the phase shifts through alternating optimization. Finally, comprehensive simulation results are presented, which not only validate the effectiveness of polarforming in combating channel depolarization but also exhibit substantial performance improvements over conventional systems.

eess.SP↗

arXiv2024

Movable Antenna-Enabled Co-Frequency Co-Time Full-Duplex Wireless Communication

Movable antenna (MA) provides an innovative way to arrange antennas that can contribute to improved signal quality and more effective interference management. This technology is especially beneficial for co-frequency co-time full-duplex (CCFD) wireless communication, which struggles with self-interference (SI) that usually overpowers the desired incoming signals. By dynamically repositioning transmit/receive antennas, we can mitigate the SI and enhance the reception of incoming signals. Thus, this paper proposes a novel MA-enabled point-to-point CCFD system and formulates the minimum achievable rate of two CCFD terminals. To maximize the minimum achievable rate and determine the positions of MAs, we introduce a solution based on projected particle swarm optimization (PPSO), which can circumvent common suboptimal positioning issues. Moreover, simulation results reveal that the PPSO method leads to better performance compared to the conventional alternating position optimization (APO). The results also demonstrate that an MA-enabled CCFD system outperforms the one using fixed-position antennas (FPAs).

cs.IT↗

arXiv2024

Secure Full-Duplex Communication via Movable Antennas

This paper investigates physical layer security (PLS) in a movable antenna (MA)-assisted full-duplex (FD) system. In this system, an FD base station (BS) with multiple MAs for transmission and reception provides services for an uplink (UL) user and a downlink (DL) user. Each user operates in half-duplex (HD) mode and is equipped with a single fixed-position antenna (FPA), in the presence of a single-FPA eavesdropper (Eve). To ensure secure communication, artificial noise (AN) is transmitted to obstruct the interception of Eve. The objective of this paper is to maximize the sum secrecy rate (SSR) of the UL and DL users by jointly optimizing the beamformers of the BS and the positions of MAs. This paper also proposes an alternating optimization (AO) method to address the non-convex problem, which decomposes the optimization problem into three subproblems and solves them iteratively. Simulation results demonstrate a significant performance gain in the SSR achieved by the proposed scheme compared to the benchmark schemes.

cs.IT↗

arXiv2023

A Contradiction to the Law of Energy Conservation by Waves Interference in Symmetric/Asymmetric mode

It can be agreed that the linear superposition and energy conservation are two independent physics laws in general. The former allows the energy to be re-distributed over space and the latter restricts the energy in the total amount. However, Levine shows the contradiction of the two laws mentioned above by creating a cleaver model that demonstrates the energy "doubling"- and "missing" phenomenon with the constrictive- and destructive interference at every point of whole space, respectively. While, he presented a wrong explanation by using one of the radiating sources to compare with an isolated source by the compensation of the impedance, where the mistake is simply analyzed in this paper. By setting up a spatial symmetric- and asymmetric-mode, we work upon Poynting theorem from the sources to the waves with the considerations of the superposition. The theoretical results reveal the invalidity of the energy conservation. Moreover, the experiments performed in the microwave anechoic chamber confirm the theoretical conclusion.

physics.gen-ph↗