Taeyun Ha
  Chihyun Song
  Donghyeon Hur
Deep Space Networks
  A deep space network is a network with a high error rate based on a high round trip time (RTT). Supplementable using FSO communication, which uses light propagating in free space to wirelessly transmit data for communication or computer networking. However, FSO communication is a technology that can help develop space exploration missions, but is heavily influenced by solar and stellar influences (such as corona turbulence) or radio distances. We would like to solve this problem through the following research.
Intellectual Merits and Broader Impacts
  (1) A Study on Reliability in Bits
  (2) A Study on Deep Space Bundle Protocol
  (3) A Study on Advanced Deep Space Communication Techniques
  (4) Broader Impact
 (1) A Study on Reliability in Bits
  Deep space communication is characterized by very high transmission delay and unstable. Communicating with the lunar probe takes several seconds, but communicating with the Pluto probe takes several hours, delays vary greatly depending on the situation, and the possible communication time may be less than the signal transmission time.
Multilink Deep space HARQ(DS-HARQ)
  Due to the nature of multi-modal multilink, the same data can be transmitted over multiple paths. If an error occurs due to HARQ on all intermediate relay nodes, automatic retransmission requests can cause severe overhead, and handling redundant data over multiple links as separate data can be very inefficient and wasteful. Therefore, this study conducted a study on DS-HARQ and error recovery applying the characteristics of the deep space environment.
 (2) A Study on Deep Space Bundle Protocol
  Deep space communication is also characterized by long distance and high signal attenuation. The average distance from Earth to the moon is about 380,000 km, and the distance from Pluto is 4.4 billion to 7.4 billion km. This long-distance transmission causes great attenuation during transmission, and the SNR of the received signal is very low.
Multilink Bundle Protocol based on Multi-Modal
  Multi-Modal-based Multilink Bundle Protocol supports multiple wireless interfaces unlike BP, which uses only a single link, connecting with multiple DTN nodes around it and transmitting them to the appropriate link according to the current link or channel state (RTT, throughput), and studies an algorithm to determine the size of Bundle or block. This is similar to the congestion control algorithm of IP-based TCP, which controls and schedules the size of blocks or bundles depending on the status of the currently connected link.
 (3) A Study on Advanced Deep Space Communication Techniques
  Based on the above studies, the throughput can be better than the existing single link. However, despite the advantages of these multi-links, we face a variety of challenges that can degrade performance, which we summarize into two in total in this study.
Development of Integrated Communication Simulation based on Space Environment and
Advanced Development of Deep Space Communication Techniques
  First, despite the development of communication environment and communication technology, data allocation methods (such as Round Robin) using fixed control policies do not respond appropriately to all events such as link errors and disconnects, resulting in a significant decrease in overall performance.
  The second is the head-of-line (HoL) blocking problem, and HoL blocking is a problem in which data transmitted through multiple paths is transmitted in a disorderly manner, ignoring data transmitted beyond the queue of the receiving end.If it is sent randomly at this time, the reception queue becomes full because the receiving node does not receive the data in order, and in the case of a general drop tail queue, it causes head-of-line (HoL) blocking that drops the received data later. Therefore, scheduling techniques for which links to allocate data are inevitable.
 (4) Broader Impact
  The project is expected to pave the way for DTN-based Multi-Modal Multilink Bundle Protocol (hereinafter referred to as Space Communication Technology) that can be used to develop mutually beneficial space and strengthen domestic space technology capabilities. The developed space communication technology can transmit control signals to probes/landers, receive lunar data, etc., and develop communication modules using domestic satellites and provide high-capacity satellite services through space communication.
스페이스 캐싱 서비스 지원 Terrestrial-CubeSat 핵심 통신 기술 연구 (Research on Core Technologies of Terrestrial-CubeSat Communication for Space Caching Service), NRF, 2023.03.01~2027.02.28
T. Ha, A. Masood, W. Na, and S. Cho, "Intelligent Multi-Path TCP Congestion Control for video streaming in Internet of Deep Space Things communication," to appear in Elsevier ICT Express, 2023. [PDF]
A. Masood, T. Ha, D. S. Lakew, N.-N. Dao, and S. Cho, "Intelligent TCP Congestion Control Scheme in Internet of Deep Space Things Communication," to appear in IEEE Transactions on Network Science and Engineering, 2023. [PDF]
A. Masood, T. Ha, D. S. Lakew, N.-N. Dao, D. T. Hua, G. Woraphonbenjakul and S. Cho, "A Review on Congestion Control for Internet of Deep Space Things Communication" in Proc. of ICOIN, Bangkok, Thailand, January, 2023. [PDF]
T. Ha, D. Lee, J. Oh, Y. Jeon, C. Lee, and S. Cho, "DTN-based Multi-link Bundle Protocol Architecture for Deep Space Communications," in Proc. of ICTC,Jeju, Korea, October, 2022. [PDF]