Opportunistic nonorthogonal cooperative communications through decode-and-forward relaying

Cooperative Communication is a wireless communication scheme, which gains signal transmission diversity through user cooperation. In cooperative communications, the existing relaying strategies include amplify-and-forward (AF) and decode-and-forward (DF). Moreover, cooperative communications through opportunistic relay selection and nonorthogonal signal transmission can further improve the system performance. In order to improve the cooperative outage probability performance, this paper proposes an advanced scheme called the opportunistic nonorthogonal DF (ONDF) scheme. It integrates the advanced cooperative features of opportunistic relaying and nonorthogonal transmission. The system model of the ONDF scheme is presented, based on which the scheme´s outage probability is analyzed. The relay selection criterion is then proposed. By analyzing the diversity-multiplexing tradeoff (DMT) performance of the proposed scheme, it is shown that the ONDF scheme has a superior DMT characteristics compared to the existing cooperative schemes. Finally, the outage probability performance of the scheme is obtained to validate the DMT analysis, showing sizeable performance gain over the existing schemes.