Energy efficient power allocation approach to asymmetric analogue network coding with rate-dependent circuit power

Energy efficiency (EE) plays an indispensable role in the battery constrained systems. In this study, the EE optimisation problem for asymmetric analogue network coding (ANC) protocol is analysed in a two-way relaying network, where the two sources have different transmission rate requirements. A generalised power consumption model is applied consisting of not only the transmit power and fixed circuit power, but also the most general rate-dependent dynamic circuit power, with which a power allocation problem is formulated to achieve the maximal EE constrained by the rate requirements as well as the total transmit power budget. By exploiting the two-layer optimisation method and non-linear fractional programming theorem, the original EE maximisation problem is solved in an efficient way. Specially, when the rate-dependent circuit power is modelled as the linear function of transmission rate, a closed-form solution is obtained. Through simulations, the proposed power allocation algorithm is verified and the impacts of some system parameters such as relay location, transmit power and transmission rate asymmetry are also provided to gain useful insights, which facilitates the energy-efficient design for the practical asymmetric ANC protocol.