A team of researchers from Columbia Engineering, have invented a technology - full-duplex radio integrated circuits (ICs) - that can be implemented in nanoscale CMOS to enable simultaneous transmission and reception at the same frequency in a wireless radio. Till now, this has been thought to be impossible as transmitters and receivers either work at different times or at the same time but at different frequencies. This Columbia team, led by Electrical Engineering Associate Professor Harish Krishnaswamy, is the first to demonstrate an IC that can accomplish this. They presented their work at the International Solid-State Circuits Conference (ISSCC) in San Francisco on February 25.
In the era of Big Data, the current frequency spectrum crisis is one of the biggest challenges researchers are grappling with and it is clear that today's wireless networks will not be able to support tomorrow's data deluge. Today's standards, such as 4G/LTE, already support 40 different frequency bands, and there is no space left for future expansion. At the same time, the grand challenge of the next-generation 5G networks is to increase the data capacity by 1,000 times. The ability to have a transmitter and receiver re-use the same frequency has the potential to immediately double the data capacity of today's networks.
The biggest challenge they faced with full duplex was canceling the transmitter's echo. Imagine that you are trying to listen to someone whisper from far away while at the same time someone else is yelling while standing next to you. If you can cancel the echo of the person yelling, you can hear the other person whispering.
This is the first solution that demonstrates an IC that that can receive and transmit simultaneously. Creating this technology in an IC is critical to bring this functionality to handheld devices such as cellular handsets, mobile devices such as tablets for WiFi, and in cellular and WiFi base stations to support full duplex communications.
This work was funded by the DARPA RF-FPGA program.
