On the Capacity of Free-Space Optical Communication Channel

• Main Authors: Ding-Jie Lin, 林鼎傑
• Other Authors: Stefan M.Moser
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/24408848306419905690

碩士 === 國立交通大學 === 電信工程系所 === 96 === In this thesis we study the free-space optical communication channeld. This channel is characterized by inputs that are nonnegative representing transmitted optical intensity, and by outputs that are corrupted by additive white Gaussian noise, because in free space the disturbances arise from many independent sources. Due to battery and safety reasons the inputs are simultaneously constrained on both their average and peak power. Our task is trying to find upper and lower bounds on the capacity of this channel. We use a numerical approach to compute the channel capacity and compare it with previous bounds. Based on the result of this comparison, we try to derive improved analytical lower bounds on capacity. Our numerical lower bounds are very close to previous upper bounds in lower SNR region (below 5 dB) with improving performance if we loosen the average-power constraint. Our analytical lower bounds are good in medium SNR region (between 5 dB and 15 dB).