Amplify-and-Forward Relaying with Ring-TCM Codes

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 and path loss. Since cooperative users utilize some degree of their transmission freedom for relaying other user’s data, cooperative transmission results in lowering each user’s spectral efficiency. Therefore, a coding scheme with both high spectral efficiency and optimized performance in fading channel would be desirable for a cooperative network. RingTrellis Coded Modulation (TCM) codes is the one of the most suitable schemes to be chosen. Two Ring-TCM coded AF cooperative systems achieving 1 bits / symbol and 1.5 bits / symbol for each user are presented. Our simulation results show that based on achieving the same spectral efficiency, the Ring-TCM codes can achieve a better diversity gain than simply combining a convolutional code with the high order modulation schemes in a cooperative AF scenario.