The Full-duplex Wireless: From Integrated Circuits to Networks (FlexICoN) project is motivated by the exponential growth of wireless traffic that calls for the design of spectrum-efficient methods.
Existing wireless systems are half-duplex, where the separation of a users’ transmitted and received signal in either frequency or time causes inefficient utilization of the limited spectrum. An emerging technology that can substantially improve spectrum efficiency is Full-Duplex (FD) communication, namely, simultaneous transmission and reception on the same frequency channel. FD operation, however, requires the cancellation of extremely powerful transmitter Self-Interference (SI) in FD receivers. Despite recent progress in the development of laboratory bench-top FD transceiver implementations, these designs mostly utilize off-the-shelf components and are not suitable for compact Integrated Circuit (IC) implementations necessary for commercial small-form-factor mobile applications. Moreover, fully utilizing the benefits of FD communication calls for a careful joint redesign of the Physical and the Medium Access Control (MAC) layers while taking into account the FD IC characteristics.
The FlexICoN interdisciplinary project directly addresses the important cross-layer challenges stemming from the need to design compact ICs and to jointly design the MAC and PHY layers. It will provide develop (i) novel antenna interfaces, (ii) circuit, architecture and system concepts for fully-integrated full-duplex transceivers, and (iii) a fundamental understanding of the impact of FD IC transceivers, designed for small form factor nodes, on algorithm and MAC layer design, and network capacity.
In order to allow the broader community to experiment with FD wireless, we integrated two generations of FlexICoN FD radios in the open-access ORBIT and COSMOS wireless testbeds. Since interfacing an RFIC canceller with a software-defined radio (SDR) presents numerous technical challenges, we implemented the RF cancellers on printed circuit boards (PCBs) to facilitate cross- layered experiments with an SDR platform. We first integrated an improved version of the FlexICoN Gen-1 RF canceller with a USRP N210 SDR in the ORBIT testbed. We then followed a similar design and integrated two FlexICoN Gen-2 RF cancellers with USRP2 SDRs in the COSMOS testbed.