methods and systems are proposed for transmitting data from a source to a destination via a relay station having multiple antennae . the relay station receives from the source a message containing the data and a first cyclic prefix . it does this using each of its antennae , so producing multiple respective received signals . in certain embodiments , the relay station removes the first cyclic prefix from the received signals , replacing it with a new one . in other embodiments , the relay station removes only a portion of the first cyclic prefix . in either case , the relay station may apply space - time coding to generate second signals , which it transmits to the destination , which extracts the data . methods are also proposed for estimating parameters of the channel , to enable the destination to decode the data .