| Relay network designs have been widely studied in recent years. It is known that cooperative relay network can achieve cooperative diversity with the help of relays and improve the data rate and/or the reliability of the network. On the other hand, green communication design has also attracted significant attention due to the drastic increase in energy consumption. We are going to investigate green communication designs in relay network in our work.;In this thesis, we adopt a novel efficiency measure, the power-normalized received signal to noise ratio (PN-SNR) in relay network design for several scenarios and analyze the performance of the proposed designs. In single-relay network and multi-relay network with a sum relay power constraint, the PN-SNR maximization problem is formulated and solved. In multi-relay network with individual power constraint on each relay, we investigate both the basic PN-SNR maximization problem and the quality of service (QoS)-constrained PN-SNR maximization problem. Performance of the proposed designs is compared with the fixed relay power scheme and the SNR-maximization scheme analytically and numerically via simulation. Our results show that with the same average relay transmit power, the PN-SNR maximizing scheme is superior to the fixed relay power scheme not only in the PN-SNR but also in the outage probability for both single and multi-relay networks. Compared with SNR-maximizing scheme, it is significantly superior in PN-SNR with moderate degradation in outage probability. Our results reveal the potential of PN-SNR as efficiency measure in relay network design. |
