Asynchronous Full Rate Cooperative Transmission for Underwater Acoustic Communication

Cooperative communication can realize spatial diversity advantages in a distributed manner and has been successfully applied to underwater acoustic communication recently. However, the conventional synchronous two-stage cooperative modes are less efficient in underwater environments due to the long synchronization time and intermittent data transmission. In this paper, an asynchronous full-rate underwater cooperative communication scheme is proposed to reduce the cooperative delay and improve the transmission rate. In the proposed scheme, the source node transmits data packets successively and two relays retransmit the even and odd frames respectively without synchronizing with other nodes. The experimental results show that the proposed scheme outperforms the direct transmission and several conventional cooperative transmission schemes in underwater environments.