Capacity study of on-off keying in the low SNR regime

This paper describes capacity results obtained on on-off keying (OOK) signaling schemes with Gaussian background noise in the low signal-to-noise ratio (SNR) regime based on latest relevant studies. Coherent and noncoherent detection of OOK signals with soft and hard decisions are all treated to perform a complete investigation. By evaluating the capacity per unit cost and the wideband slope to study the capacity behaviors at low SNR, it is shown that the Shannon limit can be achieved by both coherent and noncoherent OOK although a significant loss in spectral efficiency is unavoidable. In addition, the capacity study is also extended with the presence of Rayleigh fading.