Pseudonymetry: Precise, Private Closed Loop Control for Spectrum Reuse with Passive Receivers

Radio astronomy and other passive radio spectrum users have significant challenges avoiding interference from wireless communication systems. Even distant transmitters sometimes interfere with passive users. We propose Pseudonymetry, a system that provides (primary) passive users a means to turn off the transmissions of the particular (secondary) wireless transmitter that interferes with it. By controlling the specific transmitter rather than an entire geographical region, Pseudonymetry could increase the spectrum available for wireless systems while ensuring rapid clearing of interferers as necessary for passive use. Pseudonymetry adds a low rate watermark to the secondary (intended) transmitted signal to carry a random, anonymous pseudonym. We show the ability of a passive receiver to decode the watermark, even from a signal received with very low SNR. The passive receiver posts to a centralized database to provide feedback to the secondary transmitters so that they know to vacate the band. We provide analysis that captures the trade-offs in the design of Pseudonymetry, and show initial evidence that a simple amplitude modulation watermarking scheme could enable reliable detection at a distant passive receiver, while resulting in minimal degradation to the error performance of the intended secondary receiver.