Dr. Seohyang Kim

Post-doctoral research associate

Seoul National University

Dr. Seohyang Kim received her Ph.D. degree in Electrical Engineering and Computer Science from Seoul National University, Seoul, Republic of Korea, in August 2019. She received her B.S. degree in Computer Science Engineering from Sejong University, Seoul, Republic of Korea, in February 2013. During her doctoral programme, advertised by professor Chongkwon Kim, she studied wireless communications and explored two research themes - (1) wireless video streaming and (2) wireless multi-hop communication - and has made substantial research achievements in each (20+ papers, 6 granted patents, and 3 IETF Internet-Drafts, etc.). Currently, she is focusing on building reliable and efficient multi-hop communication techniques using Time Slotted Channel Hopping (TSCH) and the Routing Protocol for Low power and lossy network (RPL). On ACM/IEEE IPSN 2019, her recent work ALICE (Autonomous Link-based Cell Scheduling method for TSCH) was introduced. In continuation of this work, she is designing autonomous and real-time traffic load –based TSCH cell scheduling method that can be used as an independent module for any autonomous TSCH schedulers. Currently, she is interested in autonomous and reliable IoT systems based on the analysis of the collected data.

Wireless Communication techniques for multimedia streaming and multi-hop networks

Wireless video streaming is her initial research interest and she studied energy- and data- efficient video segment download scheduling methods (buffering strategy). By considering audience viewing statistics, she proposed the method that decides the amount of video segment to download at a time in the application buffer. She also studied rate adaptation technique. When multiple wireless clients share a bottleneck link, they underestimate or overestimate the available bandwidth due to on-off downloading patterns. She proposed XMAS, that is, client-side TCP acknowledgement regulation –based video rate adaptation technique. Here, by regulating TCP ACK transmission, a client makes a streaming server throttle the transmission speed, thereby each client removes on-off video segment downloading patterns using a wireless channel continuously. With the proposed method, each client using the same bottleneck link could achieve higher quality of service showing high stability, fairness and average video quality.

An autonomous and reliable multi-hop communication system is her another research interest. She focused on Time Slotted Channel Hopping (TSCH) and the Routing Protocol for Low power and lossy network (RPL). There are various scheduling methods with centralized or distributed approaches, which generate a lot of overhead for scheduling. She proposed an autonomous and link-based TSCH scheduling method. Here, each node schedules its own schedule table by hashing directional link ID and time information together. She evaluated her proposed scheme on a large public testbed and achieved performance improvement in terms of packet delivery ratio, end to end latency, and radio duty cycle. As well as TSCH, she also studied RPL routing tree construction methods by considering residual energy, traffic load and the link quality. Recently, she is designing autonomous and real-time traffic load –based TSCH cell scheduling method that can be used as an independent module for any autonomous TSCH schedulers. She is also analyzing the performance of different TSCH schedulers mathematically.