Aiming at the uplink of laser communication between airplane and satellite

the factors including the ambient light

the loss of laser propagating in atmosphere

the receiving efficiency of receiver and the laser intensity fluctuation

which all can affect the link performance

were theoretically modeled and analyzed. On the basis of the modeling and analyzing

a link bit error rate （BER） model was proposed by considering on-off-keying （OOK） modulation and di- rect-detection combined with the Webb-Gaussian approximation of avalanche photodiode detector （APD）. A numerical simulation was performed and the relationship between BER and signal laser power incident on APD was got. It shows that BER decreases while the laser power increases and an approximately log-linear relationship between decreasing speed of BER and laser power can be obtained. Finally

the minimal transmitting power

0.873W

at transmitter was computed as link could achieve 10-7 BER.