On the Throughput-Reliability Tradeoff Analysis in Amplify-and-Forward Cooperative Channels

Cooperative transmission protocols are always designed to reach the largest diversity gain and the largest network capacity simultaneously. The concept of diversity-multiplexing tradeoff (DMT) in MIMO systems put forward by Zheng and Tse has been extended to this field. In fact, many works that follow from this famous rule have been done to achieve more perfect tradeoff curves. However, the concept of multiplexing gain in DMT constrains a better understanding of the asymptotic interplay between transmission rate, frame error probability (FEP) and signal-to-noise ratio (SNR), and also fails to predict FEP curves accurately. Another formulation called the throughput- reliability tradeoff (TRT) was then proposed to avoid such limitation. Under this new rule, Azarian and Gamal well elucidated the asymptotic trends exhibited by the FEP curves in block-fading MIMO channels. Meanwhile they doubted whether the new rule can be used in more general channels and protocols. In this paper, we will prove that it does hold true in amplify-and-forward (AF) cooperative protocols. We propose a symbol based slotted amplify-and-forward (SSAF) protocol as the infrastructure to deduce the relationship between DMT and TRT. Furthermore, we derive the theoretical FEP curves predicted by TRT. We show that the FEP curves by simulation will asymptotically overlap with the theoretical curves predicted by TRT under some circumstance.