Real-time RF Emulator Simulates Channel Interactions among 256 Wireless Devices

Over the past three years, DARPA’s Spectrum Collaboration Challenge (SC2) has relied on a custom-built virtual testbed called the Colosseum to host thousands of competitive matches and scrimmages, which will include the final match to determine the winner of the $2 million grand prize. The SC2 is a first-of-its-kind collaborative machine-learning competition, where competitors have been challenged to reimagine new spectrum access strategies in which radio networks autonomously collaborate to dynamically determine how the radio frequency (RF) spectrum should be used moment to moment, avoiding interference and jointly exploiting opportunities. SC2 teams have been working onsolutions by taking advantage of recent advances in artificial intelligence (AI) and machine learning, and the expanding capacities of software-defined radios.

Working with engineers at John Hopkins University Applied Physics Lab (JHU APL) and National Instruments (NI), DARPA constructed a 256-by-256 RF channel emulator that can calculate and simulate in real-time more than 65,000 channel interactions among 256 wireless devices. This massive emulator is at a scale never before realized – 20x more total RF bandwidth than currently available in commercial systems. To replicate an array of complex RF environments – from open fields to dense cities – that put the competitors’ radio designs through their paces, the Colosseum relies on 128 two-antenna software-defined radios and 64 field programmable gate arrays (FPGAs).

Residing in a 30-foot by 20-foot server room on the campus of JHU APL in Laurel, Maryland, the Colosseum first opened its virtual doors in April 2017. Now in its final year of competition, SC2 is set to host its championship event at MWC19 Los Angeles on October 23. During the event, attendees will have an opportunity to see the Colosseum up close in the MWC19 Los Angeles exhibit hall. The emulator will travel from Laurel to Los Angeles for the three-day event to run the final competitive matches of the competition from the show floor.

Following SC2’s finale, the Colosseum’s work as a research and development testbed will continue under new management. This unique system will transition to its new home at Northeastern University, through the National Science Foundation’s (NSF) Platforms for Advanced Wireless Research (PAWR) program. The PAWR program enables experimental exploration of robust new wireless devices that seek to revolutionize the nation’s wireless ecosystem while sustaining U.S. leadership and economic competitiveness for decades to come.

The transition of the Colosseum to the PAWR program is part of NSF's ongoing investment in wireless research, including EARS (Enhancing Access to the Radio Spectrum) and, more recently, SpecEES (Spectrum Efficiency, Energy Efficiency, and Security: Enabling Spectrum for All). Over the last decade, NSF has cumulatively invested more than $150 million in this area.

This transition will serve as a key stepping stone for an experimenter to gain confidence in their spectrum usage prior to open testing outdoors using the PAWR platforms. In its new home as part of the PAWR family at Northeastern University, the Colosseum will significantly augment NSF's ongoing investments to stimulate spectrum research, providing an important resource for the broader wireless research community.

Click here, for more information on DARPA’s Spectrum Collaboration Challenge and the Colosseum.