Active sensing for dynamic spectrum access

An apparatus, comprising:

• at least one memory including computer program code;
• and
• at least one processor,
• wherein the at least one memory and computer program code are configured to, with the at least one processor, cause the apparatus at least to
• obtain an original signal to be transmitted to at least one receiver;
• watermark the original signal with at least one of authentication data or ancillary data to provide an enhanced signal, wherein watermarking the original signal comprises applying a physical layer watermark, wherein the physical layer watermark is configured to emulate at least one a channel effect or a receiver distortion;
• and
• transmit the enhanced signal to the at least one receiver.

A non-transitory computer-readable medium, encoded with instructions that, when executed in hardware, perform a process, the process comprising:

• obtaining an original signal to be transmitted to at least one receiver;
• watermarking the original signal with at least one of authentication data or ancillary data to provide an enhanced signal, wherein the watermarking comprises a physical layer watermark, wherein the physical layer watermark is configured to emulate at least one a channel effect or a receiver distortion;
• and
• transmitting the enhanced signal to at least one receiver.