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Underwater acoustic communications (UAC) feature frequency-dependent signal attenuation, long propagation delay and doubly-selective fading. Thus the design of reliable UAC protocols is challenging. On the other hand, cooperative relay communications, which have been extensively studied in terrestrial environments, are promising paradigms for reliable communications. However, their application ...

—In cognitive radio network the primary channel information is beneficial. But it can not be obtained by direct channel estimation in cognitive system as pervious methods. And only one possible way is the primary receiver broadcasts the primary channel information to the cognitive users, but it would require the modification of the primary receiver and additional precious spectrum resource. Coo...

In this letter, power allocation methods are devised for Amplify-and-Forward (AF) opportunistic relaying systems aiming at minimizing the outage probability. First, we extend the result on outage probability in [8] and develop an approximate expression to simplify the power allocation problem. A corresponding optimization problem is constructed and proved to be convex. Then an iterative numeric...

This paper proposes the Ring-TCM coded Amplifyand-Forward (AF) cooperative system, achieving both high spectral efficiency and optimized performance. In a cooperative communication network, individual users are encouraged not only to transmit their own data, but also relay other user’s data. This relaying transmission creates spatial diversity to combat the effect of individual severe fading an...