A decode-and-forward relaying protocol with partial CSIT and optimal time allocation

In this paper, we investigate a decode-and-forward (DF) relaying protocol for a three-node half-duplex single-antenna network, consisting of a single source-destination pair and a relay. The proposed relaying protocol, called DF with time allocation (DF-TA), can switch its transmission mode according to the partial channel state information at the transmitter (CSIT), which is obtained through a one bit feedback from the destination. We derive the diversity multiplexing tradeoff (DMT) of DF-TA in a closed-form, and develop an adaptive time allocation strategy to achieve its optimal DMT. We show that the DF-TA significantly improves the DMT of existing time allocation schemes with or without CSIT in DF relaying channel. Moreover, in contrast to the power control schemes based on CSIT, which are performed with the assumption of long-term power constraint, the DF-TA can be generalized to the practical scenarios where a strict short-term power constraint is imposed on, due to the environmental safety and interference prevention.