Open-Access Full-Duplex Wireless

Full-duplex (FD) wireless – simultaneous transmission and reception at the same frequency – has the potential to double network capacity at the PHY layer and to provide other benefits at higher layers. Despite extensive research, there is no open-access wireless testbed with FD-capable nodes, which is crucial for experimental evaluations of FD-related algorithms at the higher layers. To allow the broader community to experiment with FD, we developed and integrated an open-access 1st-generation narrowband RF canceller with a USRP N210 SDR in the ORBIT testbed [4]. We also developed a 2nd-generation wideband FD radio that achieves improved performance and bandwidth of RF self-interference cancellation through the technique of frequency-domain equalization (FDE) [2, 3]. We are now integrating this wideband FD radio in the COSMOS testbed [1] and provide more advanced example experiments at different layers of the network stacks (PHY, Link, and above). Detailed tutorials and demos can be found here.

Figure 1. (a) The implemented Gen-2 RF canceller consisting of a wideband frequency-domain equalization (FDE) path and a narrowband path, (b) the measured TX/RX isolation of the Gen-2 RF canceller without turning on the canceller, and with the narrowband (Gen-1)/wideband (FDE) path on, when the circulator antenna port is terminated by 50 ohm (left) and connected to an antenna (right), and (c) the implemented open-access Gen-2 canceller box and wideband FD radios integrated in the COSMOS sandbox.
Figure 2. The Gen-1 narrowband RF canceller and the open-access FD-capable node installed in the ORBIT wireless testbed.

[1] T. Chen, J. Welles, M. Kohli, M. Baraani Dastjerdi, J. Kolodziejski, M. Sherman, I. Seskar, H. Krishnaswamy, and G. Zussman, “Experimentation with full-duplex wireless in the COSMOS testbed,” in Proc. IEEE ICNP’19 Workshop Midscale Education and Research Infrastructure and Tools (MERIT), 2019. [download] [presentation]

[2] T. Chen, M. Baraani Dastjerdi, J. Zhou, H. Krishnaswamy, and G. Zussman, “Wideband full-duplex wireless via frequency-domain equalization: Design and experimentation,” in Proc. ACM MobiCom’19 , 2019. [download] [presentation]

[3] T. Chen, M. Baraani Dastjerdi, J. Welles, J. Zhou, H. Krishnaswamy, and G. Zussman, “Poster: Enabling wideband full-duplex wireless via frequency-domain equalization,” in Poster description in Proc. ACM MobiCom’19, 2019. [download] ACM MobiCom Student Research Competition (SRC) Winner – First Place

[4] T. Chen, M. Baraani Dastjerdi, G. Farkash, J. Zhou, H. Krishnaswamy, and G. Zussman, “Open-access full-duplex wireless in the ORBIT testbed,” arXiv:1801.03069v2 [cs.NI], May 2018. [download]

[5] The Columbia FlexICoN project

[6] Full-duplex experiments instructions

[7] Source code (GitHub)