A method for carrier frequency and phase synchronization of two autonomous cooperative transmitters

Cooperative communication protocols in which two or more sources transmit simultaneously in a single subchannel offer the potential for increased power efficiency and achievable rate with respect to orthogonal transmit cooperation. These protocols are, however, complicated by the fact that they require strict transmitter synchronization in order for the carrier signals from each source to arrive in phase and constructively combine at the intended destination. This paper develops an explicit method for synchronizing the carriers of two sources in a cooperative communication system with one destination. Unlike the prior work in this area, the approach described in this paper allows for source and/or destination mobility. The performance of the proposed carrier synchronization system is investigated for several channel models and practical design considerations are also discussed.