PPM Channel Parameter Estimation based on Photon Detection.

In the Pulse Position Modulation (PPM) space optical communication channel estimation based on photon detection, two schemes for the estimation of signal photon average and background photon average are proposed. Scheme 1 is based on the characteristic of M order PPM, where only one of the M soots has a sggnal optical slot. The sggnal photon average and the back-ground photon average are roughly estimated by comparing the number of photons rn each soot rn each symbol counted by the photon detector and by counting the total number of photons in each soot in the error correction frame. The proposed method rn scheme 2 js based on that n scheme 1. The sggnal optical soot poston js re-determined by dedsion feedback n the Serially Con-catenated Pulse Poston Modu!ation (SCPPM) system. Since the exsstence of SCPPM accumulator leads to error propagation, the soft information output by decoding ss irst nntereeaved, and then mapped from btt to PPM symbol after hard deiion and accumu!ation. Frnally, the poston of sggnal optical soot is re-determined to obtarn more accurate sggnal photon average and background photon average. [ABSTRACT FROM AUTHOR]