An Energy-Scalable In-Band Full Duplex Architecture

In-band full duplex (IBFD) is a promising technique that allows to potentially double the achievable bi-directional throughput over a given bandwidth. Moreover, it has been estimated that IBFD-equipped wireless networks can be more energy-efficient than half duplex ones due to the reduced energy cost of packet collisions. However, one key challenge for implementing an energy-efficient IBFD system is the cancellation of the interference produced by the transmitted signal. In fact, existing self-interference cancellation (SIC) techniques are not always energy-efficient, as the effect of the interference reduction might not be able to compensate the additional electronic power consumption introduced by the SIC module. Following this rationale, in this paper we propose and energy-efficient IBFD architecture that adapts the SIC module to the link conditions. By studying a symmetric bi-directional full duplex link, we show that the proposed architecture obtains significant energy savings by using a simple SIC scheme for short-range transmissions. More powerful SIC techniques are shown to be an energy-optimal choice only when transmitting over long link distances.