Opportunistic Relaying with Partial CSI and Dynamic Resource Allocation

In this paper, we consider the problem of minimizing the source node average power required to achieve a certain transmission rate in the existence of a relay node. Some works have considered this problem with the assumption of perfect channel state information (CSI) at the source node. We consider more practical scenarios where the source does not know the channel between the relay and the destination, but receives one-bit feedback on the state of that channel and where a maximum power constraint exists at each transmitting node. We consider two relaying protocols, namely, the Multi-Hop (MH) and the Opportunistic Decode and Forward (ODF) protocols. We derive closed form expressions for the average power required under each protocol and compare their performances with the system that assumes perfect relay-destination channel knowledge at the source node. We find that the performance is close, indicating that one-bit feedback is very useful. We also derive an upper bound on the average power required by the MH protocol, and derive the outage probability expressions for the two protocols.