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Researchers develop novel full-duplex transceiver architecture

20 May 2015

A team from the University of Bristol has developed a technique that allows a radio device to transmit and receive on the same channel at the same time.

The full-duplex transceiver under test (photo: Sam Duckerin/courtesy of the University of Bristol)

This would enable two-way communication using just one channel, and therefore half as much wireless spectrum compared with the current technology.

The novel full-duplex transceiver architecture combines electrical balance isolation and active radio frequency cancellation. The prototype can suppress interference by a factor of over 100 million and uses low-cost, small form factor technologies, making it suitable for use in mobile devices such as smartphones and tablets.

This important change in radio design could offer a range of benefits. In Wi-Fi systems this would double the capacity of a Wi-Fi access point, allowing more users and higher data rates. For cellular systems, full-duplex operation would also deliver increased capacity and data rates, or alternatively the network operators could provide the same total network capacity with fewer base station sites, giving obvious benefits in the cost and environmental impact of running the network.

“Until now there has been a fundamental unsolved problem with radio communication," says Leo Laughlin, a PhD student from the University’s EPSRC Centre for Doctoral Training (CDT) in Communications. "Since the radio spectrum is a limited resource, and with network operators paying billions of pounds to access the spectrum, solving this problem would bring us one step closer to the faster, cheaper and greener devices of our connected future.”

As well as being part of the evolution to 5G mobile, this research is also relevant to the design of the radio circuitry in current 3G and 4G cellular mobile devices. In today’s mobile devices, a separate filtering component is required for each frequency band, and because of this, current mobile phones do not support all of the frequency channels in use across the world.

Different devices are manufactured for different regions of the world, and there are currently no 4G phones capable of unrestricted global roaming. Replacing these filters with the research team’s duplexer circuit would create smaller and cheaper devices, and would allow manufacturers to produce a single model for the entire world. This would enable global roaming on 4G and would further decrease cost through greater economies of scale.

The team (Leo Laughlin, a PhD student from the University’s EPSRC Centre for Doctoral Training (CDT) in Communications, together with MSc student Chunqing Zhang, supervisors Professor Mark Beach and Dr Kevin Morris, and industrial mentor, Dr John Haine at u-blox) have published papers about their research in the IEEE Journal on Selected Areas in Communications special issue on full duplex radio, and in this month’s issue of the IEEE Communications Magazine. Patents have been filed to protect the novel duplexer design.


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