K. J. Ray Liu (Chinese: 劉國瑞; pinyin: Liú Guó Ruì; Pe̍h-ōe-jī: Lâu Kok-sūi; born February 11, 1961, Taiwan) is an American scientist, engineer, educator, and entrepreneur.
[1][19] Verizon Fios launched Home Awareness and Signify, formerly known as Philips Lighting, did SpaceSense in 2022 enabled by Origin's wireless AI technology.
In the recent decade, his focus has been on the development of AI analytics for wireless sensing and indoor tracking using ambient radio signals.
Liu was the first to bring time-reversal to the practice and use of our daily life by leveraging radio-frequency multipaths in indoor or multipath-rich environments and prove that it can work effectively.
[44] He further showed that when there is a large enough number of multipath signals (such as indoor environments), the time-reversal focusing spot exhibits a stationary behavior in its energy distribution.
Specifically, in the limit of large time-resolved multipath signals, the time-reversal spot has a spatially independent structure that follows a Bessel function power distribution.
This is an unprecedented discovery in that one can now accurately/reliably estimate/detect the speed of a moving object indoors without line-of-sight; the more multipaths, the better the performance, defying and contrary to any prior scientific beliefs.
Not only did it enable accurate tracking of an unlimited number of subjects, indoors, and without costly infrastructure or a priori measurements, it also served as the theoretical foundation for accurate/reliable wireless sensing by simply using ambient radio waves, including Wi-Fi.
From now on, wireless sensing is becoming an integrated part of the technology infrastructure, especially for 5G/6G when bandwidth is large enough to harness more multipaths and most IoT devices are connected to deliver smart home/office/city.
[44][19][49] Liu also pioneered cross-layer design using antenna arrays for wireless communications in 1997 by first introducing the seminal concept of duality between uplink and downlink for joint transmit beamforming and power control to increase the number of users in a cellular network by 100x.
This work provides a seminal first step toward achieving full-diversity in multiple-input multiple-output (MIMO) broadband OFDM systems that are commonly used in modern wireless communications standards such as 4G/WiFi and beyond.
He showed the endless possibilities of cooperation in a series of seminal works to establish cooperation as a communication paradigm that can improve communication performance, expand transmission coverage area; improve energy efficiency and extend network lifetime; and increase throughput and stability region for multiple access schemes.
[55][44] Liu was among the first to employ game theory to devise optimal solutions and strategies in cognitive radio for dynamic spectrum access, allocation, sharing, sensing, security, and anti-jamming.
[56][44] His pioneering works created the game-theoretic foundation for cognitive networking by developing new framework of joint learning and decision making such as Chinese Restaurant Games.
DataPort received the 2023 ASAE Power of Associations Summit Award, ASAE’s highest honor for the association community, conferred for its work to bring a valuable data platform to the global community and is helping achieve the mission of the IEEE by "fostering technological innovation and excellence for the benefit of humanity”.