Blind detection of on-off keying for free-space optical communications

We investigate blind detection, i.e. detection assuming the absence of instantaneous channel state information (CSI) and a statistical channel description at the receiver, of on-off keying (OOK) in a free-space optical (FSO) system. Using an observation window encompassing many consecutive independent bits, our blind detector capitalizes on the fact that the atmospheric turbulence is constant over the observation window and that the expected number of transmitted 1s and 0 s are equal. To improve receiver performance beyond that of the initial blind detector, we also consider the use of decision-aided threshold estimation and a second detection stage, respectively. Provided that a sufficiently large observation window is employed, simulation results indicate that the proposed receiver can attain performance comparable to that of the lower performance bound given by detection with CSI.