Determine average probability of error for the system

Question

Solve the following problem:

Consider an (N_T , N_R) = (2, 1) MIMO system that employs the Alamouti code to transmit a binary sequence using binary PSK modulation. The channel is Rayleigh fading characterized by the channel vector

h = [h11 h12]^t

with E|h11|² = E|h12|² = 1. The additive noise is zero-mean Gaussian. Determine the average probability of error for the system.