The CBS methodology has been utilized in order to make a rapid broadcast of emergency alert based on cellular systems. We present a synchronous cooperative communication method for the CBS. Especially, we suggest a synchronization scheme and a data recovery approach for high-rate cooperative communications. For the high-rate transfer of emergency alert, the cyclic prefix is added to the preamble for the synchronization. For the data recovery, the Alamouti technique is utilized on frequency domain, which is similar to SC-FDE. The simulation results confirm that our proposed scheme is very suitable for the CBS.