Adaptive optimal transmit power allocation for two-hop non-regenerative wireless relaying system

In order to combat fading in wireless networks and increase the capacity of a system, cooperation is allowed among the terminals in a network. The adaptive optimal power allocation (PA) scheme, based on a certain system performance, is an important issue for relaying routing and network operation. The paper analyzes the two-hop non-regenerative (NR) relaying channel with and without diversity, and investigates the optimal PA scheme between the source terminal (Tx) and the relaying terminal (RS) under power constraints. Since, in real relaying environments, the transmitter usually knows the instantaneous channel state information (ICSI) of the 1st hop and the statistical channel state information (SCSI) of the 2nd hop, the proposed PA schemes are based on two-hop ICSI and two-hop mixed channel state information (MCSI) respectively. With the adaptive scheme, the system performance not only outperforms that of the direct transmission system, but also obtains the maximum channel capacity or SNR of the relaying system.