An Alamouti coded OFDM transmission for cooperative systems robust to both timing errors and frequency offsets

In this letter, we propose an Alamouti coded orthogonal frequency-division multiplexing (OFDM) scheme for a cooperative communication system robust to both timing errors and frequency offsets. OFDM with cyclic prefix (CP) is used to combat timing errors. In order to mitigate the intercarrier interference (ICI) caused by multiple frequency offsets in the cooperative system, an ICI-self cancellation scheme is constructed, which can suppress ICI effectively. Moreover, in the proposed scheme, if the channels are real-valued fading channels, the received signals at the destination node have the Alamouti code structure on each subcarrier and thus it has the fast symbol-wise ML decoding and when frequency offsets are not large, the new scheme can achieve diversity order 2.