Chunip: Charging-Uninterrupted In-Band Parallel Communication for Magnetic MIMO Wireless Power Transfer System

As magnetic resonant coupling (MRC)-based wireless power transfer (WPT) systems continue to evolve, in-band receiver (RX) feedback communication becomes essential for achieving tighter integration, adaptive power control, and reliable system coordination. However, existing on-off keying-based in-band communication inherently interrupts the charging process, leading to reduced charging efficiency and rendering it unsuitable for the frequent feedback required by mainstream standards. In this paper, we propose Chunip, a charging-uninterrupted in-band parallel feedback communication mechanism for MIMO MRC-WPT systems, achieved by integrating resistive load modulation with channel matrix matching. To address the exponential growth of the channel states and dynamic channel variations, we introduce a three-mode RX modulation scheme and a hypothesis-testing-inspired method for efficient channel matrix collection. Moreover, we employ a performance-guided online update strategy that adaptively reuses stable historical information to preserve accurate channel matching despite load fluctuations and RX movements. We develop a Chunip prototype and conduct comprehensive evaluations. Experimental results demonstrate that our system achieves over 95% communication accuracy when serving 12 RXs simultaneously and delivers 27.69% more power than existing state-of-the-art solutions.