We develop a new construction criterion for BSPK space-time codes which simultaneously reflects both "coding" and "diversity" advantage. Furthermore, we propose a new method of improving the performance of space-time codes, naemly bit interleaving. Subsequently we provide a computationally effective, iterative way of decoding bit interleaved space-time codes. At the end we note the 2dB gain due to the new approach. We note the sixteen state code which operates close to 3dB from the outage probability.