Yuchul Kim

yuchul.kim@gmail.com

Education

Ph.D. in Electrical Engineering, The University of Texas at Austin

M.S. in Electrical Engineering, KAIST

B.E. in Electrical Engineering, Korea University

Research Interests

Wireless systems, wireless networks, 3G/4G/5G/6G cellular networks, IEEE WiFi, backscatter communicaiton system, PHY/MAC protocols, HW, RF, IoT, AI/ML for connected systems, LLM

Work/Research/Project Experiences

@Qualcomm

Extended reality (XR) - power and capacity (Rel-17)

Research/standardize UE power saving techniques for XR.
- It is quite challenging to support XR traffic with pseudo periodic packet arrival, high bit rate, and low latency requirement with regular CDRX like mechanism. Enhanced CDRX mechanism w/ non-uniform periodicity, L1-based sleep indication, jitter handling with fast WUS, retransmission-less UL transmission schemes were designed showing UE power saving gain of up to 40%.

Performance evaluation of XR capacity
- Based on split rendering based architecture in sub-6G with potential enhancements including CG/SPS enhancements, delay aware scheduling, etc
External publications
- “UE Power Saving Techniques for Extended Reality (XR) Services in 5G NR Systems”, IEEE PIMRC, 2021
- “Performance Evaluation of Extended Reality Applications in 5G NR System”, IEEE PIMRC, 2021

PDCCH skipping

Low Power Wakup Signal (Rel-18+)

Internal research and standardization
- Companion receiver monitoring low power wake-up signal (LP-WUS) with very low power while main radio is in sleep mode. Detection of WUS triggers main radio wake-up from sleep state achieving significant reduction of UE energy consumption.
- Coverage of WUS, power budget analysis, receiver architectures, waveform for LP-WUS (OOK4 - DFT-s-OFDM) and low power synchronization signal (LP-SS).
- RRM offloading to LP-WUR from main radio to reduce main radio wake ups.
- Power saving gain > 70% is achieved in Idle mode w/ sparse paging arrival.

Ambient IoT (Net-zero Energy Cellular-based IoT for 5G)

Energy harvesting based low complexity / low power 5G IoT device to address indoor/outdoor inventory/sensor/command use cases.
Feasibility study
- Use case analysis (Rel-18 SA1), link budget analysis for indoor/outdoor (Rel-18, RAN)
- Power budget/consumption analysis for low complexity/power device (Rel-19 SI, RAN1)
- Device types/architecture study for passive(backscatter) and active radio (feasibility of RF filtering, clocks (LO), transmitter, receiver architecture, RF envelop detector, mixer, modulation scheme), device/deployment cost analysis, system architecture analysis, comparison study with competing technologies (Rel-19 SI, RAN1)
System designs for passive device for indoor with external CW node (Rel-19 WI, RAN1)
- Waveform/modulation/coding: DFT-s-OFDM based OOK, square-wave based FDM in D2R link, FEC, etc
- Physical channels/signals: PRDCH/PDRCH, preamble, midamble, postamble for SFO estimation
- Procedures including 4-step random access for inventory process, duty cycled operation
System designs for active devices for outdoor
- Waveform/modulation/coding enhancements
- Physical channels/signals enhancement for CFO estimation/compensation
- Procedures for duty cycled operation to support active device with device power saving
External activities
- Leading the discussion in 5G America for debriefing paper "Evolving Devices for 5G adoption briefing paper" (link)
- NGA 6G Technologies White papers (2022, 2023) on zero energy communication (link)
- 3GPP RAN1 Feature leads for Device architecture agenda (Rel-19 SI) and D2R link enhancements (Rel-20 SI)
- Guest editors for IEEE Communication Standard Magazine
  - Guest editorial (link)
  - Review/promoting "Low-Complex Waveform, Modulation, and Coding Designs for 3GPP Ambient IoT" (link)
  - Review/promoting "Fast inventory for 3GPP Ambient IoT considering Device unavailibility due to Energy harvesting" (link)
External publications
- “Challenges and Advances in Ambient IoT within 3GPP”, IEEE Comm. Magazine, vol 64, 2026 (link)
- “Improving Query-Response Performance of Ambient IoT with CDM”, IEEE Globecom, 2025

@Apple

3GPP 5G Standard Research (Rel-16)

RAN1 delegate for following topics / internal research / feature designs / evaluation
- PDCCH monitoring skipping mechanism, search space-set switching
- Dynamic MIMO layer indication
- UE-preferred information feedback
- Cross-slot scheduling
- Dynamic TDD / GC-PDCCH / Slot Format Information
- CBG-based (re)transmission scheme
- Control channel design
- BWP

4G/5G link-level Simulator Development

Led a group of people in FW team to build simulation framework for technology evaluation in standardization and product development
Built scalable simulation framework pipeline for cloud server farms / storage farms
Built entire framework from extensible structure, parameter configuration, data collection, parallelization(multi-core, server farm), logging, job submission, performance calibration, etc for efficient and fast development

Modem Algorithm Design and Analysis

Proprietary algorithms for cellular modem (implemented in firmware)
Designed adaptive receive/transmit antenna switching mechanism for GPRS / LOG analysis (built in-house log processing tool)
HARQ algorithm design/evaluation for Wi-Fi
Designed dynamic packet error rate estimation algorithm for Wi-Fi
Designed throughput estimation algorithm for Wi-Fi
Designed low power on-demand discovery mechanism
Designed low power HARQ buffer management mechanism for LTE

Wi-Fi System Research and Development

Developed object oriented event-driven system simulation framework (with CSMA MAC protocols, PHY abstraction, Packet scheduling, Traffic models, etc) for simulating multiple interacting STAs and APs for algorithm evaluation and product development
Research IEEE 802.11ax systems and simulator development (Tx/Rx/Channel Modeling/ OFDMA /QAM/ DCM/ Preambles/ channel estimation/ interleaver/etc.)
Support WiFi standard team
IOT test with product team

@Samsung

3GPP2 standardization

Upper layer signaling

Link-level/System-level Simulator Development

Developed and maintained system/link-level simulator (using C/C++) to evaluate the performance of H-ARQ schemes, AMC schemes, and VoIP support mechanism

PUBLICATIONS

THESIS

“Spatial Spectrum Reuse in Wireless Networks Design and Performance”, Ph.D Thesis, The University of

Texas at Austin, May 2011 (link)

“Consideration of spurious timeout in proxy for improving the performance of wireless TCP”, MS Thesis,

KAIST, Feb, 2003

JOURNAL

Yuchul Kim, Le Liu, Kazuki Takeda, Bin Han, Ville Vintola, Chao Wei, Piyush Gupta, Chengjin Zhang, Zhifei Fan, Kiran Mukkavilli, Peter Gaal, Juan Montojo, Tingfang Ji, “Challenges and Advances in Ambient IoT within 3GPP”, IEEE Comm. Magazine, vol 64, 2026
Sandeep Narayanan Kadan Veedu, Yuchul Kim, Thiemo Voigt, Guest Editorial for “Ambient Internet of Things”, IEEE Comm. Standards Magazine, 2025
Wanshi Chen, Juan Montojo, Juho Lee, Mansoor Shafi, Yuchul Kim, “The Standardization of 5G-Advanced in 3GPP”, IEEE Comm. Magazine, vol 60, 2022
Yuchul Kim, Francois Baccelli, Gustavo de Veciana, “Spatial Reuse and Fairness of Mobile Ad-Hoc Networks with Channel-Aware CSMA Protocols,” IEEE Trans. Information Theory, vol 60, issue 7, pp. 4139 - 4157, July, 2014.
Yuchul Kim, Gustavo de Veciana, “Joint Network Capacity Region for Cognitive Networks: Heterogeneous Environments and RF- environment Awareness,” IEEE Jour. Select. Areas in Comm., vol. 29, pp. 407-420, Feb 2011.
Yuchul Kim, Gustavo de Veciana, “Is Rate Adaptation Beneficial for Inter-session Network Coding?,” IEEE Jour. Select. Areas in Comm., vol. 27, pp. 635-646, June 2009.
Yuchul Kim, Jeongsoo Jung, Beomsik Bae, Daegyun Kim, P. R. Rajkotia, Youngkyun Kim, “Upper layer enhancements for fast call setup in cdma2000 revision D,” IEEE Comm. Magazine, pp. 57-64, Apr 2005.
Yuchul Kim, Dongho Cho, “Considering Spurious Timeout in Proxy for Improving TCP Performance in Wireless Networks,” Elsevier Computer Networks, vol. 44, pp. 599-616, Apr 2004.
Yuchul Kim, Dongho Cho, “Considering Spurious Timeout in Proxy for Improving TCP Performance in Wireless Networks,” IEEE Comm. Letter, vol 8, pp. 30-32, Jan 2004.

CONFERENCE

Patchava Raviteja and Piyush Gupta, Xiaoxia Zhang and Junyi Li, Zhifei Fan, Kazuki Takeda,Yuchul Kim, “Improving Query-Response Performance of Ambient IoT with CDM”, IEEE Globecom 2025
Yuchul Kim, Hwan-Joon Kwon, Olufunmilola Awoniyi-Oteri, Prashanth Hande, Jay Kumar Sundararajan, Yeliz Tokgoz, Tao Luo, Kiran Mukkavilli, Tingfang J, “UE Power Saving Techniques for Extended Reality (XR) Services in 5G NR Systems”, IEEE PIMRC, 2021
Jay Kumar Sundararajan, Hwan-Joon Kwon, Olufunmilola Awoniyi-Oteri, Yuchul Kim, Chih-Ping Li, Jelena Damnjanovic, Shanyu Zhou, Ruifeng Ma, Yeliz Tokgoz, “Performance Evaluation of Extended Reality Applications in 5G NR System”, IEEE PIMRC, 2021
Yuchul Kim, F. Baccelli, G. de Veciana, “Spatial reuse and fairness of mobile ad-hoc networks with channel-aware CSMA protocols,” Seventh Workshop on Spatial Stochastic Models for Wireless Networks (SpaSWiN), pp, 360 - 365, May 2011.
Yuchul Kim, G. de Veciana, “Understanding the Design Space for Cognitive Networks,” Sixth Workshop on Spatial Stochastic Models for Wireless Networks (SpaSWiN), pp, 418-423, May 2010.
Yuchul Kim, G. de Veciana, “Is Rate Adaptation Beneficial for Inter-session Network Coding?,” MILCOM, Nov 2008.
J. Cho, Y. Chang, Yuchul Kim and J. Chon, “Analytic Optimization of H-ARQ Throughput in Wireless Packet Data Systems,” IEEE Globecom, Nov 2006.
Yuchul Kim, J. Jung, B. Bae, D. Kim, “The Enhanced Slotted Mode Operation Considering Call Interarrival Time Distribution in cdma2000 Networks,” IEEE Vehicular Tech. Conf., vol 2, pp 683-687, May 2006.
Yuchul Kim, D. Cho, “Considering Spurious Timeout in Proxy for Improving TCP Performance in Wireless Networks,” IEEE Globecom 2003, vol. 22, pp. 3673-3677, Dec 2003.
Yuchul Kim, J. Kwan, M. In, Y. Kim, D. Cho, “Effective way to improve the response time of short term bursty TCP traffic,” IEEE Vehicular Tech. Conf., vol 2, pp. 889-893, May 2002.

PATENT

>500 patents filed and/or granted (link)