I2SR: Immediate Interrupt Service Routine on RISC-V MCU to Control mmWave RF Transceivers

In 5G technology, millimeter Wave (mmWave), known as Frequency Range 2 (FR2), is one of the candidates for next-generation mobile communications. However, the adoption of mmWave technology in transceiver systems faces challenges in terms of strict latency requirements, due to the significantly increased number of control and compensation tasks. In this paper, we propose a novel interrupt architecture, Immediate Interrupt Service Routine (I
²
SR) on a RISC-V MCU, enabling zero-latency context switching. Applied to the mmWave transceiver, our I
²
SR MCU efficiently handles the mmWave tasks by removing context switching overhead. In our experiment, I
²
SR architecture reduces the overall MCU utilization by 30.6% compared to the baseline MCU, thereby demonstrating that I
²
SR architecture satisfies the strict latency requirements essential for mmWave applications.