Custom RF Hardware for Large-Scale Wireless Networking Testbeds Enabling Emerging Wireless Communication Paradigm Reseach

Harish Krishnaswamy, Gil Zussman and Peter Kinget, Columbia University

Next generation (“5G”) wireless communication networks are targeting extreme (1000x) increases in data capacity in order to serve society’s ever-increasing demand for wireless data and to power the Internet of Things. Such an increase necessitates the exploration and deployment of new wireless communication paradigms, such as full-duplex wireless, millimeter-waves and massive MIMO.

A large-scale wireless networking testbed that would enable to the academic community to perform research on these emerging paradigms cannot uniquely rely on off-the-shelf commodity hardware such as USRPs (Universal Software Radio Platforms) as they typically do not include the analog and RF circuitry required. For instance,

• full-duplex wireless requires self-interference cancellation in the antenna, RF and analog domains, necessitating custom designs that can interface with USRPs,

• USRPs that can operate in the millimeter-wave frequency range (30GHz and beyond) fundamentally do not exist, and the usage of laboratory benchtop equipment from vendors such as Keysight proves prohibitively expensive, particularly for large-scale testbeds, and

• while massive MIMO testbeds based on USRPs have been explored, a significant challenge is the absence of RF/analog spatial interference mitigation, limiting the signal processing techniques considered to digital and stressing the dynamic range requirements of the RF and analog circuitry.

 Figure 1. (a) A 4-node Energy Harvesting Active Networked Tags (ENHANTs) testbed with a software-based light control system, and (b) a USRP-based full-duplex wireless node using a custom-designed RF self-interference canceller and an off-the-shelf circulator.

The Columbia high-Speed and Millimeter-wave IC (CoSMIC) Lab, led by Prof. Harish Krishnaswamy, the Wireless and Mobile Networking (WiMNet) lab, led by Prof. Gil Zussman and the Analog and RF IC Design Research group, led by Prof. Peter Kinget, have a long track record of

• RF and millimeter-wave IC design research for full-duplex [1],[3], millimeter-waves [1], massive MIMO [1] and low-power transceivers for the Internet of Things [5],[4],

• the deployment of testbeds based on custom RF and millimeter-wave ICs [3],[4] , and • wireless networking research for emerging communication paradigms based on the constraints

imposed by realistic IC-based hardware [2],[3],[4]. Prof. Harish Krishnaswamy would like to represent Columbia University at the “Communities of Practice” workshop to share our experiences in (i) designing custom analog and RF hardware for these extremely-challenging wireless paradigms, (ii) interfacing such hardware with commodity USRPs, and (iii) providing abstracted interfaces to the hardware to enable network-layer research.

References

[1] http://cosmic.ee.columbia.edu/publications.html [2] http://wimnet.ee.columbia.edu/publications/ [3] http://flexicon.ee.columbia.edu/publications [4] http://enhants.ee.columbia.edu/publications [5] http://www.cisl.columbia.edu/kinget_group/publications.html