RF-RBComm: Pilotless Beamforming and Uplink-Downlink Frequency Separation Method

Traditional beamforming technology improves communication efficiency through high directivity, but its complex beam control mechanism increases system latency. Moreover, its reliance on pilot signals transmitted by the target makes it difficult to apply in passive target scenarios. To address these issues, we propose deploying a retrodirective antenna (RDA) array at both the transmitter and receiver. The base station (BS) actively transmits signals, while the user equipment (UE) uses the RDA to reflect the signals back to the BS along the original path, thereby establishing an adaptive communication link. To eliminate echo interference during round-trip transmission, a phase-locked loop (PLL) is introduced to assist the RDA, achieving signal conjugation while simultaneously enabling uplink and downlink frequency conversion. Simulation results confirm that this scheme not only automatically establishes communication links but also achieves high spectral efficiency communication.