2G/3G/4G/5G Celluar Systems (2G/3G/4G/5G 셀룰러 시스템)

2G/3G/4G/5G Cellular Systems (2G/3G/4G/5G 셀룰러 시스템)

We had extensive studies on 2G/3G/4G/5G cellular systems with the following technical issues:

• Call admission control

• Capacity estimation

• Handoff/CDMA soft handoff

• Power control

• 2D/3D mobility modeling

• Mobility management in mobile networks

• Cognotive radio/multiuser diversity

• Cooperative communications/Cooperative relay networks

• Scheduling

• Medium access control (MAC) protocols

• Resource management

• Multi-hop radio systems

• Link- level/System-level simulators for 2G/3G/4G, etc. 

As the CDMA cellular system was developed in Korea at the first time in the world in 1996, we shifted our research interests to CDMA cellular systems, even further to 3G, 4G, and 5G systems. We have carried out our extensive studies on radio resource management issues including capacity estimation, soft handoff, mobility modeling and management, power control, scheduling, MIMO, cognitive radio, cooperative communications, WLAN/WPAN and cross-layer problems. We contributed to enhancing the 3G system performance by developing system-level simulators to evaluate the system performance of the Korean commercial IMT-2000 system with base stations, GPRS packet networks, radio network controllers, and mobile switching system, which was demonstrated for the first time in the world during the World-cup Soccer Game period, and transferred them to a Korean company.  We also developed various link-level/system-level simulators for 3G/3.5G/4G systems including WCDMA, 1xEVDO, CDMA-TDD, HSDPA, HSUPA, and LTE-adv systems and transferred them to Korean and US companies. The unique attribute of our contributions is that our research work has been directly linked to the world’s first CDMA cellular system developed by ETRI, 3G/3.5G systems world-firstly deployed in Korea, the world’s first Mobile WiMaX system, and even 4G and beyond 4G systems, while at the same time providing theoretical foundations on radio resource management issues.

 We have performed several projects including 4th Generation mobile communication system, Digital Multimedia Broadcast (DMB), High Speed Uplink Packet Access (HSUPA), and MIMO scheduling systems.  In the 4G project, we developed an OFDMA-based multi-hop system-level simulator for a speed/channel/media adaptive WiBro system using OPNET and proposed a spatial multiplexing and inter-cell interference mitigation scheme using the radio channel information of base station and relay station. The system-level simulator is used to evaluate the performance of the OFDMA-based multi-hop systems in terms of throughput and packet delay, and the proposed scheme enhances the system throughput through simultaneous transmissions of relay stations.

Digital Multimedia Broadcasting (DMB) is a digital radio transmission system for sending multimedia to mobile devices. This T-DMB project was a joint project of over 10 LABs and led by the Mobile Multimedia Platform Center (MMPC) which was funded from IITA and TI. The objective of the T-DMB project was to develop a DMB receiver using a TI’s DSP chip solution. We implemented the protocol part of the DMB receiver.

In the HSUPA project, we developed a link/system level simulator to evaluate the performance of HSUPA of 3GPP. The HSUPA stands for the High Speed Uplink Packet Access. The entire physical functional blocks in the HSUPA are implemented in the link level simulator. Moreover, it is possible to evaluate the link performance under various radio channels. The system level simulator is used to evaluate the performance of the system. Our system level simulator includes various types of traffic model and user distributions to analyze the system performance for varying system parameters.

In the joint research project with Intel Korea R&D Center, we have investigated efficient MIMO scheduling algorithms with medium access control and radio resource management in multi-dimensional radio resource environments. We have proposed a two-dimensional channel estimation scheme for classifying the each user's channel status in the respect of geometry and mobility and also proposed adaptive MIMO transmission schemes that dynamically select an appropriate MIMO mode according to varying channel status. Furthermore, we have extended to apply the geometry and mobility information to the design of an optimal dynamic scheduler in multi-user MIMO systems. Link/system level simulators developed by our lab were exhibited at the CTIA-Wireless Exhibition 2006 held at Las Vegas, USA. The CTIA-Wireless Exhibition is the most popular exhibition about wireless communications in USA. Our simulator models demonstrated at the exhibition include link/system level simulator of High Speed Downlink Packet Access (HSPDA) of 3GPP, and WLAN MAC simulators.

■System Level Simulators for Performance Evaluation

• IMT-2000 mobile switching center

• CDMA-TDD simulator

• 3G mobile communication systems

• WCDMA

• 1xEV-DO Rel.0/Rev.A 

• HSDPA 

• HSUPA

• WiBro systems

• IMT-2000 GPRS network simulator

• 3GPP LTE(Long-Term Evolution)

3GPP LTE Simulators 

HSDPA Link Level Simulator

HSDPA System Level Simulator 

HSUPA Simulator

CTIA Exhibition at Las Vegas, 2006

Major achievements are summarized as follows:

•   Many pioneering studies on capacity estimation and call admission control in 2G/3G CDMA systems  including interference-based channel assignment, capacity estimation in multi-class, single- and multi-code, and multiple-chip-rate CDMA systems

•   Pioneering theoretical work on CDMA soft handoff issues including mathematical modeling, characterization, and channel allocation for soft handoff problems

•   Extensive work on mobility modeling and management,  a pioneer to first analyze the 3-D mobility modeling and traffic analysis in three-dimensional indoor buildings

•  Development of system level simulators for evaluating the performance of the Korean IMT -2000 system with base stations, radio network controllers, GPRS packet networks, and mobile switching center, which was demonstrated for the first time in the world during World-cup period (2002) and verification of the required specifications of the IMT-2000 system.

•  Development and technology  transfer of link-level/system-level simulators for WCDMA, 1xEVDO, CDMA-TDD, HSDPA, HSUPA, LTE, LTE-Adv, and WLAN MAC systems  to Samsung, SKT, ETRI, and Intel

•     101 international journal papers and 157 international conference papers in radio resource management area

•   134 domestic or international patents  in radio resource management area

•   28 Ph.D degrees with dissertations in this area

(1) Selected Papers

   <Call Admission Control>

• • J.W.Chang, J.H. Chung, D.K.Sung, “Admission Control Scheme for Soft Handoff in DS-CDMA Cellular Systems Supporting Voice and Stream-Type Data Services,” IEEE Trans. on Vehicular Technology, vol. 51, no. 6, pp.1445-1459, Nov. 2002.

  •  S.M.Shin, D.K.Sung, “Adaptive Channel Assignment for Different Types of Traffic in DS-CDMA Cellular Systems,” Telecommunication Systems, Vol.14, pp.141-162, Aug. 2000.

  •  S.M.Shin and D.K.Sung, “Interference-Based Channel Assignment for DS-CDMA Cellular Systems,” IEEE Trans. on Vehicular Technology, vol.48, no.1, pp.233-239,1999.

  •  S.M.Shin, D.K.Sung, "DS-CDMA Reverse Link Channel Assignment Based on Interference Measurements,” Electronics Letters, vol. 31, no. 22, pp.1897-1899, 1995, etc.

           <  Capacity Estimation >

•  D.K.Kim, D.K.Sung, “Capacity Estimation for a Multicode CDMA System with SIR-Based Power Control,” IEEE Trans. on Vehicular Technology, vol .50, no .3, pp.701-710, May 2001

• D.K.Kim, D.K.Sung, “Capacity Estimation for an SIR-based Power-Controlled CDMA System Supporting ON-OFF Traffic,” IEEE Trans. on Vehicular Technology, vol.49, no.4, pp.1094-1101, July 2000.

• S.J.Lee, H.W.Lee, D.K.Sung, “Capacities of Single-Code and Multi-code DS-CDMA Systems Accommodating Multiclass Services,” IEEE Trans. on Vehicular Technology, vol.48, no.2, pp.376-384, March, 1999.

• S.J.Lee, D.K.Sung, "Capacity Evaluation for DS-CDMA Systems with Multi-Class On/Off Traffic,” IEEE Communications Letters, vol. 2, no.6, pp. 153-155, June 1998, etc.

 <  Handoff / CDMA Soft Handoff >

• J.W.Chang, J.H. Chung, D.K.Sung, “Admission Control Scheme for Soft Handoff in DS-CDMA Cellular Systems Supporting Voice and Stream-Type Data Services,” IEEE Trans. on Vehicular Technology, vol. 51, no. 6, pp.1445-1459, Nov. 2002.

• J.W.Chang, D.K.Sung, “Adaptive Channel Reservation Scheme for Soft Handoff in DS-CDMA Cellular Systems,” IEEE Trans. on Vehicular Technology, vol. 50, no.2, pp.341-353, March 2001

• D.K.Kim, D.K.Sung, “Traffic Management in a Multicode CDMA System Supporting Soft Handoffs,” IEEE Trans. on Vehicular Technology, Vol.51, No.1, pp.52-62, Jan. 2002.

• D.K.Kim, D.K.Sung, “Characterization of Soft Handoff in CDMA Systems,” IEEE Trans. on Vehicular Technology, vol.48, no.4, pp.1195-1202, July, 1999.

• J.K.Kwon, D.K.Sung, “Soft Handoff Modeling in CDMA Cellular Systems,” IEEE VTC '97, pp.1548-1551, 1997.

• S. Park, H.S. Cho, D.K. Sung, “Modeling and Analysis of CDMA Soft Handoff,” Proc. of IEEE VTC '96, pp.1525-1529, 1996

•  S.M.Shin, H.Lee, D.K.Sung, “CDMA Reverse Link Capacity Estimation Considering Handoff Effects,” Int. Workshop on Multi-dimensional Mobile Communications, MDMC '94, serial 1, 1994, etc.

  < Power Control >

• • • •  S.J.Kwon, Y.W. Chung, D.K.Sung, “Queueing Model of Sleep Mode Operation in Cellular Digital Packet Data,” IEEE Trans. on Vehicular Technology, vol. 52, no. 4, pp.1158-1162, July 2003

      • J.H.Kim, D.K.Sung, “Performance of Single-Bit Adaptive Step-Size Closed-Loop Power Control Scheme in DS-CDMA Systems,” IEICE Trans. on Communications, E81-B, no. 7, pp.1548-1552, July, 1998, etc. 

 < 3D Mobility Modeling/Mobility Management >

• • •  T.S.Kim, J.K.Kwon, D.K.Sung, “Mobility Modeling and Traffic Analysis in Three-Dimensional High-Rise-Building Environments,” IEEE Trans. on Vehicular Technology, vol.49, no.5, pp.1633-1640, Sep. 2000.

    • T.S.Kim, M.Y.Chung, D.K.Sung and M. Sengoku,"Mobility Modeling & Traffic Analysis in 3-Dimensional Indoor Environments,” IEEE Trans. on Vehicular Technology, vol.47, no.2, pp.546-557, 1998.

    • T.S.Kim, M.Y.Chung, D.K.Sung, "Mobility and Traffic Analyses in 3-Dimensional PCS Environments,” IEEE Trans. on Vehicular Technology, vol. 47, no.2, pp.537-545, 1998, etc.

             <Mobility Management in IP & Mobile Networks>

• S.J.Kwon, S.Y. Nam, H.Y. Hwang, D.K.Sung,“Analysis of a Mobility Management Scheme Considering Battery Power Conservation in IP-Based Mobile Networks,” S.J.Kwon, S.Y. Nam, H.Y. Hwang, D.K.Sung, IEEE Trans. on Vehicular Technology, vol. 53, no.6, pp.1882-1890, Nov. 2004.

• Y.W. Chung, S.J. Kwon, D.K. Sung,“An Enhanced Scheme for Combined Mobility Management Based on a New Mobile Station State Model in GPRS,” IEICE Trans. on Communications, vol.87E-B, no.7, pp.1746-1749, June 2004.

• Y.W.Chung, M.Y.Chung, D.K.Sung,“Effect of Personal Mobility Management in Mobile Communication Networks,” IEEE Trans. on Vehicular Technology, Vol. 52, No. 5, pp.1254-1269, Sep. 2003. 

• Y.W. Chung, D.K. Sung,“Delayed Group Registration Scheme in Group Location Tracking,” IEE Electronics Letters, Vol. 39, No. 17, pp. 1274-1275, Aug. 2003.

• Y.W.Chung, D.K.Sung, A.H.Aghvami,“Steady State Analysis of P-MIP Mobility Management,” IEEE Communications Letters, Vol. 7, No. 6, pp.278-280, June 2003.

• Y.W.Chung, D.K.Sung, A.H.Aghvami,“Effect of Uncertainty of the Position of Mobile Terminals on the Paging Cost of an Improved Movement-Based Registration,” IEICE Trans. on Communications, Vol.E86-B, No.2, pp.859-861, Feb. 2003.

• Y.W.Chung, M.Y.Chung, D.K.Sung,“Adaptive Algorithm for Mobile Terminal Power ON/OFF State Management,” Computer Communications, vol. 24, pp.1411-1424, 2001.

             < Cognitive Radio/ Multi-user Diversity >

• • • T.W. Ban, W. Choi, D.K. Sung, “Capacity and Energy Efficiency of Multi-User Spectrum Sharing Systems with Opportunistic Scheduling,” IEEE Trans. On Wireless Communications, vol. 8, no. 6, pp. 2836-2841, June 2009.

    • T.W. Ban, W. Choi, B.C. Jung, D.K. Sung, “Multi-User Diversity in a Spectrum Sharing System,” IEEE Trans. On Wireless Communications, vol. 8, no. 1, pp.102-106, Jan. 2009.

    • M.S. Kang, B.C. Jung, D.K. Sung, W. Choi, “Pre-whitening Scheme in MIMO Spectrum-Sharing Environment,” IEEE Communications Letters, vol. 12, no.11, pp.831-833, 2008, etc.

 < Cooperative Communications >

• J. Kim, S.H. Moon, D.K. Sung, “Hybrid Scheduling Scheme for a Cooperative Relay System in Heterogeneous Traffic Environments,” IEEE Trans. on Wireless Communications, vol. 8, no. 7, pp.3868-3877, July 2009.

• T.W. Ban, W. Choi, B.C. Jung, D.K. Sung, “A Cooperative Phase Steering Scheme in Multi-Relay Node Environments,” IEEE Trans. On Wireless Communications, vol. 8, no. 1, pp.72-77, Jan. 2009

• M.S. Kang, B.C. Jung, D.K. Sung, “Effect of Cooperative and Selection Relaying Schemes on Multiuser Diversity in Downlink Cellular Systems with Relays,” JCN, vol. 10, no. 2, pp.175-185, June 2008, etc.

   < Scheduling >

•  Y.J. Hong, J. Kim, D.K. Sung, “Two-dimensional Channel Estimation and Prediction for Scheduling in Cellular Networks,” IEEE Trans. On Vehicular Technology, vol. 58, no. 6, pp.2727-2740, July 2009.

• S.Y. Baek, Y.J. Hong, D.K. Sung, “Adaptive Transmission Scheme for Mixed Multicast and Unicast Traffic in Cellular Systems,” IEEE Trans. On Vehicular Technology, vol. 58, no. 6, pp.2899-2908, July 2009, etc.

  <Resource Management>

• S.M. Kim, B.C. Jung, W. Choi, and D.K. Sung, “Effects of Heterogeneous Mobility on Rate Adaptation and User Scheduling in Cellular Networks with HARQ,” IEEE Trans. On Vehicular Technology, vol. 62, no. 6, pp.2735-2748, 2013. 

• Y.I. Seo and D.K. Sung, “Adaptive Real-Time Polling Service for On-Line Gaming Traffic in IEEE 802.16e/m System,” IEEE Communications Letters, Vol. 14, No. 10, pp.987-999, Oct. 2010.

• Y.W.Kim, D.K.Kim, J.H.Kim, S.M.Shin, D.K.Sung, “Radio Resource Management in Multiple-Chip-Rate DS/CDMA Systems Supporting Multi-Class Services,” IEEE Trans. on Vehicular Technology, Vol .50, No. 3, pp.723-736, May 2001.

•  H.S.Cho, J.K.Kwon, D.K.Sung, “High Reuse Efficiency of Radio Resources in Urban Microcellular Systems,” IEEE Trans. on Vehicular Technology, Vol.49, No.5, pp.1669-1677, Sep. 2000.

 (2) System Simulators

Various types of link-level simulators and system-level simulators were developed  as follws:

•    A System-level Simulator for IMT-2000, including RNC, MSC, Packet Networks for verifying the performance of the world-first IMT-2000 system during the World-Cup Soccer Game, LG, 2002.

•   A System-level Simulator for the HSDPA and WiBRo that were deployed first in the World, SKT, 2005

•   A System-level Simulator for the world-first HSUPA, SKT, 2006

•   System-level Simulators for cdma 1xEVDO, WCDMA, and HSDPA transferred to Intel, 2005

The related projects are listed as follows: 

• IMT-2000 Network Protocol Architecture (1999)

• System Simulator of IMT-2000 Radio Network Controller System (1999-2000)

• System Simulator for IMT-2000 Mobile Switching System (2001)

• System Simulator for IMT-2000 Packet Networks (2001)

• Development of link-level/system level simulators for CDMA-TDD (2001)

• Development of link-level/system level simulators for WCDMA (2005)

• Development of link-level/system level simulators for HSDPA (2005)

• Development of link-level/system level simulators for 1x EVDO (2005)

• Development of Simulators for the EDCA MAC of IEEE 802.11b, a, g, e WLAN Systems (2005)

• Development of link-level/system level simulators for HSUPA (2006)

• Development of link-level simulator for 3GPP LTE (long term evolution) and LTE-Advanced System (2009), etc.

 (3)    Book Chapters in Cellular & Wireless Networks

•  D.K. Sung, J. Kim, Book Chapter 10: Performance Evaluation of HSDPA/HSUPA Systems, pp.357-378, HSDPA/HSUPA Handbook, Edited by Borko Furht and Syed Ahson, CRC Press, Oct., 2010.

• D.K. Sung, J.W. Chong, S.M. Kim, “Coexistence Issues between Zigbee and Other Networks in 2.4GHz Band,” Zigbee Network Protocols and Applications, edited by Chonggang Wang, Tao Jiang, and Qian Zhang, Auerbach Publication, August, 2010.

       (4)  Research Projects

• Beyond 4G System Technologies, 2011-2015.

• Beyond 4G and Cognitive Radio Systems, 2009-2010.

• Performance Analysis a Satellite -based IMT-Advanced System, 2008-2009.

• Cooperative Communications, 2008.

• Mobile Broadband Communications Based on OFDM, 2006-2008

• Hybrid Multiple Access Scheme for Next Generation Mobile Communication Systems, 2007

• Scheduler Design of MIMO-OFDM Systems, 2006-2007

• Performance Analysis of the HSUPA System, 2006.

• Development of DMB Receiver, 2006

• Cross-Layer Problems in 4G & WiBro Evolution Systems, 2005-2006

• Traffic Modeling and Scheduling Schemes, 2004-2005

• Performance Evaluation of Orthogonal Frequency and Orthogonal Code Hopping Multiplexing, 2004-2005

• System Level Simulators of 3G Mobile Communication Systems, 2004-2005.

• Performance Evaluation of HSDPA and WiBro Systems, 2004-2005.

• Efficient Resource Management Based on Statistical Multiplexing for the WiBro System, 2004.

• Radio Resource Allocation and Multiplexing Schemes in 4G Mobile Communication Systems, 2003-2004

• Performance Evaluation of Statistical Orthogonal Code Hopping Multiplexing, 2002.

• Core Technology in System beyond IMT-2000, 2001-2002.

• Development of a CDMA-TDD Simulator, 2001.

• Core Technology in 4G Mobile Communication Systems, 2000-2001.

• LEO Mobile Satellite Communication Network Architecture, 2000.

• QoS Control in IMT-2000 Systems. 2000.

• Capacity Expansion of W-CDMA Mobile Communication Systems, 2000.

• Microcell Configuration and Radio Resource Management in Urban Microcellular Systems, 1998.

• Evolution Strategy of IMT-2000 Network, 1998.

• AIN-Based IMT-2000 Network, 1997-1998.

• Fast Handoff Scheme in Wireless ATM Networks, 1997.

• Study on FPLMTS Network Architecture, 1997.

• Multimedia Soft Handoff, 1997.

• Basic Studies on Broadband Personal Communication Networks, 1996-1997.

• Study on PCS Network Architecture, 1995.

• Study on Broadband Personal Communication Networks, 1995.

• Feasibility Study on PCN, 1993, etc.