In this paper we derive optimal power allocation scheme that minimizes bit error rate (BER) while satisfying the average power constraint and peak to average power ratio (PAPR) constraint (which translates to minimizing the PAPR). The power allocation is done in space and time for multiple-input single-output (MISO) systems over Rayleigh flat fading channels assuming perfect channel state information (CSI) is available both at the transmitter and receiver. This power allocation achieves exponential diversity while satisfying the PAPR constraint.