For mobile users without antenna arrays, transmission diversity can be achieved with cooperative space-time encoded transmissions. This paper present a channel and delay estimation algorithm for asynchronous cooperative diversity in Rayleigh Block-Flat-Fading channel. We present a precoding frame-based scheme with packet-wise encoding. This precoding is based on the addition of a cyclic prefix which is implemented as a training sequence. This scheme offers us additional known symbols and we show that it enables best synchronization and channel estimation which reaches the Cramer-Rao Bound. We derive the performance analysis for equal and unequal channel gains. The BER performances corroborate with the analytical expressions and the full diversity order is achieved. In addition, the FER performances are depicted.