  In this paper, the paradigm of thermal noise communication (TherCom) is put
forward for future wired/wireless networks with extremely low power
consumption. Taking backscatter communication (BackCom) and reconfigurable
intelligent surface (RIS)-based radio frequency chain-free transmitters one
step further, a thermal noise-driven transmitter might enable zero-signal-power
transmission by simply indexing resistors or other noise sources according to
information bits. This preliminary paper aims to shed light on the theoretical
foundations, transceiver designs, and error performance derivations as well as
optimizations of two emerging TherCom solutions: Kirchhoff-law-Johnson-noise
(KLJN) secure bit exchange and wireless thermal noise modulation (TherMod)
schemes. Our theoretical and computer simulation findings reveal that noise
variance detection, supported by sample variance estimation with carefully
optimized decision thresholds, is a reliable way of extracting the embedded
information from noise modulated signals, even with limited number of noise
samples.
