On the design of space-time code for fast fading channels

In this paper, a new criterion of space-time code (STC) for fast fading channels is proposed minimizing the first-event error probability based on the probabilities of first-event errors with different lengths. Some new QPSK STCs are designed according to the new criterion. Simulation results show that these codes outperform the existing codes. This criterion can be suitably applied to more complex codes as well.