On the energy-bandwidth tradeoff for AWGN relay channels

This paper investigates the energy-bandwidth trade-off of various relaying strategies over the AWGN channel. The total energy consumption per information bit includes the receiver circuit processing energy at the relay and destination as well as the transmitted energy. With the cooperation of the source and relay, the end-to-end bandwidth efficiency can be improved at the cost of receiver processing energy. We consider both decode-and-forward and amplify-and-forward strategies. Energy-bandwidth tradeoffs for the decode-and-forward and amplify-and-forward relaying strategies are compared. It is shown that for low rates, the case without cooperation outperforms the case with cooperation for both strategies. However when the energy required for processing at the receiver is ignored, it is helpful to cooperate for the amplify-and-forward scheme while the result depends on the desired rate for the decode-and-forward scheme. It is also shown that the amplify-and-forward scheme does not achieve the minimum energy per bit at low SNR due to its noise propagation characteristic. Bounds on the minimum total energy consumption are derived and compared with the result without cooperation.