  We consider the problem of secret key agreement in Gaussian Maurer's Model.
In Gaussian Maurer's model, legitimate receivers, Alice and Bob, and a
wire-tapper, Eve, receive signals randomly generated by a satellite through
three independent memoryless Gaussian channels respectively. Then Alice and Bob
generate a common secret key from their received signals. In this model, we
propose a protocol for generating a common secret key by using the result of
soft-decision of Alice and Bob's received signals. Then, we calculate a lower
bound on the secret key rate in our proposed protocol. As a result of
comparison with the protocol that only uses hard-decision, we found that the
higher rate is obtained by using our protocol.
