The paper “Sensing-Throughput Tradeoff for Cognitive Radio Networks” by A*STAR’s Institute for Infocomm Research (I2R) won the prestigious IEEE Communications Society Award for Advances in Communication this year.
This award recognises high quality papers that open new lines of work, envision bold approaches to communication and formulate new problems to solve in the field of communications engineering. Only 1 paper is awarded annually. In some years, no award was given when the papers are deemed to be less qualified.
The winning paper was cited over 3400 times and ranked as the 3rd most cited paper in Web of Science among over 9590 papers published in the IEEE Transactions on Wireless Communications journal. A trailblazer in the early days of cognitive radio, the winning paper was the first to establish the mathematical model to jointly optimise both spectrum sensing and communication time for optimum bandwidth use in wireless communication systems, paving the way for faster connections.
We interviewed two authors of this paper from the I2R team, who shared with us how they conceived this award-winning paper and its subsequent impact on global research in the communications field.
What inspired you to work on this research?
Dr Zeng:
With the rapid development of wireless technologies coupled with the increased proliferation of wireless networks, radio spectrum becomes limited as primary users take up these bandwidths.
As more applications are developed, it soon became apparent that solutions are needed to allow sharing of these channels (spectrum reuse). Many thus explored cognitive radio as it improves spectrum efficiency by enabling secondary users to temporarily utilise the unused license spectrum of primary users. To support this spectrum reuse functionality, it is critical to effectively switch from secondary users to primary users once they are active to protect their right of use.
We discovered this fundamental design problem and started the research to derive the optimum time needed for spectrum sensing to ensure adequate protection of the primary user while optimising usage for other applications (spectrum exploitation).
What was the key discovery?
Dr Hoang:
For cognitive radio networks, the more time you spent on sensing, the better the protection for the primary users. However, it results in less time for the secondary users to utilise the channel.
These are fundamental trade-offs which no one has pointed out during those days. Most people are researching on either spectrum sensing or spectrum exploitation.
We are the first to point out the correlation of these two and how it is closely related to the efficiency of these channels. Through our novel mathematical model, we derived on the optimal percentage of time needed for sensing to protect primary user while enhancing use of channel for the secondary users. This optimised the use of the available spectrum.
How did it impact future technologies after the discovery?Dr Zeng:
There are many new technologies that explores the optimum use of these unused or underutilised spectrum eg: TV Whitespaces. It was through this discovery that many researchers started to realise the need to derive the optimal time needed for sensing to optimise the use of their solutions.
Dr Hoang:
There is a constant shortage of radio spectrums, while wireless applications are increasing. There will always be a group of users or applications of higher priority than others.
It is key to be mindful in the development of new technologies and systems where there is a fundamental trade-off which they can calculate to help in the prioritising of users in their solutions.
“Sensing-Throughput Tradeoff for Cognitive Radio Networks”, Ying-Chang Liang, Yonghong Zeng, Edward C.Y. Peh, and Anh Tuan Hoang; IEEE Transactions on Wireless Communications, vol. 7, no. 4, pp. 1326–1337, April 2008.