Communication systems have accelerated over a thousandfold in the past 20 years, increasing opportunities for users to utilize communication services exceeding gigabit speeds. However, TCP, the transmission control protocol for end-hosts has often failed to keep pace, resulting in more instances where sufficient data transfer speeds cannot be achieved. Particularly, situations where TCP data transfer performance degrades when communication lines experience delay and errors have become more pronounced.

The awardees pioneered the development of ultra-high-speed TCP technology (TCP-FSO), achieving a thousand-fold increase in data transfer speed through an innovative new concept (Figure 1)[1]. This ultra-high-speed TCP technology maintains compatibility with the widely adopted TCP while achieving dramatic performance improvements through cross-layer congestion control, which synchronizes TCP and IP/Ethernet flow control, and delay-based acknowledgment rate control, which drastically reduces the amount of acknowledgment packets. In 2009, the awardees conducted tests emulating international communication environments on a 13,600 km 10Gbps cable with a packet loss rate of 0.2%. They demonstrated that the ultra-high-speed TCP achieved 7.89 Gbps, 665 times faster than the 11.5 Mbps effective performance of conventional high-speed TCP (Figure 2). Furthermore, in 2011, the awardees pioneered the demonstration that Ultra-High-Speed TCP could achieve a maximum data transfer rate of 10 Gbps in mobile communications using optical spatial communication, a technology anticipated for future ultra-high-speed wireless communications (Figure 3). Furthermore, the awardees demonstrated that in space networks utilizing optical spatial communication satellite constellations, ultra-high-speed TCP achieves file transfer performance exceeding 720 Mbps—over a thousand times faster than conventional methods—under simulated conditions with a 30% bit error rate and 0.5-second round-trip delay.

In 2012, the awardees commercialized a device called the TCP-Booster, equipped with ultra-high-speed TCP technology. The TCP-Booster is widely utilized by broadcasters, telecommunications carriers, and research institutions, generating cumulative business results exceeding 25 billion yen (Figure 4) [2]. Specifically, broadcasters have introduced TCP-Boosters at 50 stations nationwide, enabling the faster production of high-definition video programming. Telecommunications carriers have also achieved high-speed data transfer with minimal distance dependence on a wide-area virtual network connecting the East Coast of North America and Japan.

Looking ahead to the future, ultra-high-speed TCP technology is also expected to contribute to realizing energy-efficient network systems. For example, analytical evaluations confirmed that leveraging the error resilience of ultra-high-speed TCP technology in high-efficiency communication line design can increase the communication capacity of trans-Pacific submarine cables from 100 Tbps to 160 Tbps without requiring additional power supply to the cable (Figure 5) [3]. Furthermore, for mobile communications where radio wave utilization is rapidly advancing, a backhaul has been proposed, using optical spatial communication, which avoids radio wave interference. It has been confirmed that ultra-high-speed TCP technology is effective for enhancing the speed and reliability of this backhaul [4].

These research achievements have been highly acclaimed both domestically and internationally. The awardees have received the IEEE ICC2024 Best Paper Award, IEEE ICC2020 Best Paper Award, Kanto Regional Invention Encouragement Award (2017), Electrical Science and Technology Encouragement Award (2015), AIAA ICSSC 2011 Excellent Paper Award, the Photonics Network Research Award from this Society (2020), and the Internet Architecture Research Award from this Society (2017).

As described above, this achievement is outstanding in both academic and industrial aspects and is worthy of this Society's Achievement Award.

References

1. Y. Hasegawa, J. Katto, "A Transmission Control Protocol for Long Distance High-Speed Wireless Communications", IEICE Trans. on Commu., vol.E101.B, no.4, 2018.
2. Y. Hasegawa, J. Katto, “Development of TCP/IP Data Transfer Throughput Enhancement System,” IEICE Trans. on Commu. Japanese edition, Vol.J101-B, No.10, OCT 2018.
3. Y. Hasegawa, et. al., “Optical Communication Capacity and Quality to Maximize End-user TCP/IP Throughput,” IEEE ICC, 2020.
4. Y. Hasegawa, et. al., “Free-Space Optical Communication System with Wide-Steering Beam for Terrestrial Access Networks,” IEEE ICC, 2024.