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Researchers Mix Full and Half Duplex Wireless to Enhance Spectral Efficiency

June 13, 2016 By Molly White in

Researchers at New York University’s (NYU) Tandon School of Engineering and Trinity College in Dublin, Ireland have come up with a new way to enhance spectral efficiency of wireless networks, enhance network reliability and speed up the rate at which data can be downloaded – at least theoretically.

The research team’s method entails installing a mix of full- and half-duplex radios in cell base stations. The details are set out in a white paper entitled, ¨Throughput and Coverage for a Mixed Full and Half Duplex Small Cell Network,” which recently won first prize at the IEEE International Conference on Communications in Kuala Lumpur, Malaysia, Science Daily reports. 

Mix Full and Half Duplex Wireless

Able to transmit and receive digital signals simultaneously over the same frequency channel, full duplex radios can double the spectral efficiency of wireless networks. What has prevented them from being adopted widely is that interference doubles as well.

Half-duplex radios can send and transmit digital data over the same frequency channel as well, but only alternately, as in ¨push to talk¨ telecommunications and walkie-talkies. On the plus side, interference is reduced and coverage area is larger for half-duplex radios.

Led by NYU Tandon Professor of electrical and computer engineering Shivendra Panwar and Ph.D. student Sanjay Goyal along with Trinity College Assistant Professor Nicola Marchetti and doctoral student Carlo Galiotto, the research team created a mathematical model and ran simulations that optimize a mix of full- and half-duplex radios according to various cell network configurations and traffic conditions.

Panwar likened the use of full-duplex radios in cell base stations to being at a lively party. “Even if you were capable of speaking and listening at the same time, everyone around you would be doing the same thing,’ he was quoted as saying. “It would be impossible to tune out that extra noise, and the same is true in a full duplex system. There are many more outages and dropped calls due to the high level of interference.”

Enhance Spectral Efficiency

Download volumes greatly exceed upload volumes on digital networks. In their paper, the team showed that wireless network operators could speed up downloads at the expense of upload speeds, which customers would be less likely to notice.

“The beauty of this system is that it’s tunable and would allow providers to adjust the mix of cells based on the needs of a region,” Goyal explained. “If you’re designing an urban network, the demand for bandwidth is much greater than the need for wide-area coverage. More full duplex cells would provide that bandwidth, even at the cost of a few more dropped calls,” he explained. The reverse is true in less dense areas, where spectral efficiency is less crucial.¨