WLAN/WPAN/Coexistence of WLAN and WPAN

WLAN/WPAN/Coexistence of WLAN and WPAN (무선 근거리통신망/무선 개인영역통신망/ WLAN 과 WPAN의 상호공존)

Main Content of WLAN/WPAN/Coexistence of WLAN and WPAN:

• Wireless Local Area Networks (WLAN)

• Ultra Wide Band (UWB) Technology

• Coexistence Problem between WLAN and WPANs

• Ubiquitous Fashionable Computer (UFC) Project

• MAC / Power Management / Mobility Management

WLAN and WPAN communication systems operate in unlicensed ISM (Industrial, Scientific, and Medical) band. These systems interfere with each other because they operate in the same radio frequency band. We have proposed several interference mitigation schemes such as a multi-channel clustering algorithm for ZigBee networks, a Ubiquitous Wearable Computer (UWC)-aided coexistence algorithm for WLAN and ZigBee networks, a near-interference erasure scheme for impulse radio based UWB systems, and a MIMO-based collision resolution scheme in WLANs. The performance of IEEE 802.11 WLAN system has been mathematically analyzed based on a Markov process model.

Research Issues on WLAN

• New WLAN MAC Structure for Supporting Multi-Rates and Fairness (S. J. Kim, Ph.D. Dissertation, 2007)

• Saturation Performance Analysis of IEEE 802.11 WLAN under the Assumption of No Consecutive Transmissions (S. J. Kim, IEICE Trans. Commun., 2007)

• Performance Improvement of Error-Prone Multi-Rate WLANs through Adjustment of Access/Frame Parameters(B. H. Jung, ICC09)

• Enhanced Medium Access Control in QoS Enabled WLANs (H. W. Hwang, Ph.D. Dissertation, 2008)

• Performance Analysis of IEEE 802.11e EDCA with a Virtual Collision Handler (H. W. Hwang, IEEE Trans. VT, 2007)

• Goodput Analysis of a WLAN with Hidden Nodes under a Non-saturated Condition [J. W. Yang, submitted in IEEE Trans. Wireless Comm. 2008]

• Cross-Layer Performance Analysis for CSMA/CA System: Impact of Imperfect Sensing [J. W. Chong, IEEE SPAWC, 2008]

• Analysis of CSMA/CA Systems under Carrier Sensing Errors: Throughput, Delay, and Sensitivity [J. W. Chong, IEEE Globecom, 2008]

• A MIMO-Based Collision Mitigation Scheme in Uplink WLANs (H. Jin, IEEE Comm. Letter, 2008)

• Performance Comparison of Uplink WLANs with Single-User and Multi-User MIMO Schemes (H. Jin, IEEE WCNC08)

WLAN DCF MAC Simulator

WLAN EDCA MAC Simulator 

Advanced  WLAN for QoS Support

Multi-Hop Simulator

CTIA Wireless Communication Exposition, Las Vegas, 2006

Research Issues on UWB(Ultra-Wide Band)

<Multiple Access Control (MAC) for UWB Systems>

• Statistical Multiplexing-Based Hybrid FH-OFDMA System for OFDM-Based UWB Indoor Radio Access Networks (J. W. Chong, IEEE Trans. MTT, 2006)

• Orthogonal Time Hopping Multiple Access (OTHMA) (C. Y. Jung, PH.D. Dissertation, 2008)

• Pre-Arbitrated Slot Allocation (PASA) MAC Protocols (C. Y. Jung, PH.D. Dissertation, 2008)

<Performance Enhancement of TH-PPM UWB System>

• Link Performance Evaluation of a TH-PPM UWB System in the Presence of Multi-User Interference (M. J. Kim, IEEE ICUWB05)

• Performance Enhancement of a TH-PPM UWB System Using a Near-Interference Erasure Scheme in Multi-User Environments [M. J. Kim, IEEE ICUWB06)

• Capacity Analysis of a TH-PPM UWB system using a Near-Interference Erasure Scheme in Multi-User Environment (S. M. Kim, IEEE PIMRC07)

Coexistence Problems in the 2.4GHz ISM Band Using WLAN/WPAN Protocols

<Interference measurements and analysis>

• Experiments on Interference and Coexistence between ZigBee and WLAN Devices Operating in the 2.4 GHz ISM Band (S. M. Kim, NGPC05)

• Analysis of Throughput in a ZigBee Network under the Presence of WLAN Interference (J. W. Chong, IEEE ISCIT07)

• Analysis of Throughput and Energy Consumption in a ZigBee Network under the Presence of Bluetooth Interference (J. W. Chong, IEEE Globecom07)

<Node-centric interference mediation scheme>

• Ubiquitous Wearable Computer (UWC)-Aided Coexistence Algorithm in an Overlaid Network Environment of WLAN and ZigBee Networks (B. H. Jung, IEEE ISWPC07)

<Network-centric interference mediation schemes>

A ZigBee piconet can operate the interference mediation scheme to guarantee data transmission of ZigBee network using a supporting node to control the WLAN network. In addition, both WLAN and ZigBee networks can secure some proper data communication time and throughput.

• Adaptive Interference-Aware Multi-Channel Clustering Algorithm in a ZigBee Network in the Presence of WLAN Interference (M. S. Kang, IEEE ISWPC07)

• Interference Mediation Schemes for IEEE 802.11 WLAN and IEEE 802.15.4 ZigBee Networks (B. H. Jung, IEEE PIMRC08)

      <Power Saving Scheme for Terminal with Multiple Radio Interfaces>

• Energy-aware communication module selection through ZigBee paging for ubiquitous wearable computers with multiple radio interfaces (S. M. Kim, IEEE ISWPC07)

Ubiquitous Fashionable Computer (UFC) Project

• Overall Goal: Development of Ubiquitous Wearable Computer Technology

• Communication Team's Research Issues

  • Efficient multimode communications

    • Interference-aware multimode communications --> Improvement of communication quality is achieved through an intereference avoidance algorithm.

    • Energy-aware multimode communications --> Battery lifetime can be extended through energy-aware power saving slgorithm.

  • Interoperable seamless communications

    • Auto-configuration algorithm --> Auto-configuration recognizes heterogeneous networks. Its functions include interference awareness, coordination, management and display between multiple communication interfaces. It has a GUI tool to manage communication devices of UFC.

    • Vertical handoff algorithm between WLAN and WPANs --> Interoperable seamless communication is achieved through vertical handover between WLAN and WPANs.

We have carried out a research project including Ubiquitous Fashionable Computer (UFC).   In the UFC project, we have developed a fashionable, suitable, flexible, functional, and social wearable ubiquitous terminal in next generation ubiquitous computing environments. The UFC project was funded from IITA and 14 LABs and 2 companies are participated in this project. We demonstrated and exhibited our results to the public at the KINTEX Exhibition Hall. Low-interference and Low-power consumption multimode communication algorithms have been proposed and implemented to efficiently communicate with in the ubiquitous environments.

UFCs developed through the UFC project have been demonstrated on the Next Generation Computing Industrial Exhibition 2006 at KINTEX in Korea. In this exhibition, we demonstrated our UFC on the fashion-show and exhibited it to the public through a booth demonstration. The catchphrase of our UFC team was ‘Throw Information! Ubiquitous Fashionable Computer!’.

A ZigBee sensor network testbed has been established in CHIPS building. We have performed experiments on the operations of the ZigBee communication system and the effect of interference between WLAN and WPAN systems. Research on localization and location tracking using this testbed has been performed by undergraduate students. They received an excellence award through this research supported by URP (Undergraduate Research Program).

Figure 1  Ubiquitous Fashionable Computer

Publicity & Exhibition for the UFC Project

• NGC(Next Generatio Computer) Exhibition & Fashion Show, COEX, Nov. 2005.

• KAIST VIP Demonstration, Nov. 2006.

• NGC Exhibition & Fashion Show, KINTEX, Nov. 2006.

• MBC 9 o'clock News Broadcast, Nov. 2006.

• KBS Morning Talk Show Broadcast, Nov. 2006.

• Demonstration for ITIR (Taiwan) Visitors, May 2007.

Figure 5  Exhibition at COEX (2005), KINTEX (2006) and KAIST for the UFC Project

(1) Journal Papers

•    J.Y. Kim, H. Jin, J.B. Seo, S.H. Kim, and D.K. Sung, “Adaptive Transmission Control for Uplink/Downlink Fairness in Unsaturated CSMA Networks,” IEEE Communications Letters, vol. 23, no. 10, pp. 1879-1882, Oct. 2019.

• J.Y. Kim, S.H. Kim, and D.K. Sung, “Hybrid ARQ-based Uplink/Downlink Fairness Enhancement in WLAN,” IEEE Trans. On Vehicular Technology, vol. 67, no. 10, pp. 10107-10111, Oct. 2018.

• J.Y. Kim, S.H. Kim, D.K. Sung, “Hybrid ARQ-based Fairness Enhancement in Uplink WLAN,” IEEE Trans. On Wireless Communications, vol. 17, no. 7, pp.4362-4373, July 2018.

• J.Y. Kim, H. Jin, S.H. Kim, and D.K. Sung, “Backlog Estimation for Uplink/Downlink Fairness in Unsaturated Bidirectional CSMA Networks,” IEEE Communications Letters, vol. 21, no. 12, pp.2702-2705, December 2017.

• J.Y. Cha, H. Jin, and D.K. Sung, “Fair Channel Access in Uplink WLANs Supporting Multi-Packet Reception with Multi-User MIMO,” IEEE Communications Letters, vol. 20, no. 10, pp. 2075-2078, Oct. 2016.    

•  J.W. Chong, C.H. Cho, H.Y. Hwang, and D.K. Sung, “An Adaptive WLAN Interference Mitigation Scheme for ZigBee Sensor Networks,” International Journal of Distributed Sensor Networks (IJDSN) (Hindawi), vol. 2015 (2015), Article ID 851289, 16 pages, 2015. August 2015.(Invited Paper)

• H. Jin, J.B. Seo, and D.K. Sung, “Stability Analysis of p-Persistent Slotted CSMA Systems with Finite Population, “IEEE Trans. On Communications, vol. 62, no. 12, pp.4373-4386, Dec. 2014.

• J.W. Chong, H.Y. Hwang, D.K. Sung, and Y. Nam, “A Comprehensive Analysis of Association Process for IEEE 802.15.4 Wireless Networks,” Int. Journal of Ad Hoc and Ubiquitous Computing, vol. 16, no. 1, pp.70-77, June 2014. https://doi.org/10.1504/IJAHUC.2014.062491

• B.H. Jung, N. Song, and D.K. Sung, “A Network-assisted User-Centric WiFi-Offloading Model for Maximizing Per-User Throughput in an Overlay Network,” IEEE Transaction on Vehicular Technology, vol. 63, no.4, pp.1940, 1945, May 2014.

• H.Y. Hwang, S.J. Kim, B.S. Kim, D.K. Sung, S. Park, and Y.U. Chung, “Modeling and Analysis of  Wireless LANs with a Backoff  Freezing  Mechanism,” Information, vol. 15, no. 3, pp.1081-1094,  March, 2012.

• Ho Young Hwang, Sun-Jong Kwon, Yun Won Chung, Dan Keun Sung, and Suwon Park, "Modeling and Analysis of an Energy Efficient Mobility Management Scheme in IP-Based Wireless Networks," Sensors, vol. 11, no. 12, pp.11273-11294, Dec. 2011.

• H. Jin, B.C. Jung, and D.K. Sung, “A Tradeoff between Single-User and Multi-User MIMO Schemes in Multi-Rate Uplink WLANs,” IEEE Trans. On Wireless Communications, vol. 10, no. 10, pp.3332-3342, Oct. 2011.

•  J.W. Chong, Y. Sung, D.K. Sung, “Cross-Layer Performance Analysis for CSMA/CA Protocols: Impact of Imperfect Sensing,” IEEE Trans. On Vehicular Technology, Vol. 59, No. 3, pp. 1100-1108, March 2010.

•  J.W. Yang, J.K. Kwon, H.Y. Hwang, D.K. Sung, “Goodput Analysis of a WLAN with Hidden Nodes under a Non-Saturated Condition,” IEEE Trans. On Wireless Communications, Vol. 8, No. 5, pp.2259-2264, May 2009.

• J.W. Chong, Y. Sung, D.K. Sung, “RawPEACH: Multi-Band CSMA/CA-Based Cognitive Radio Networks,” JCN Special Issues in Cognitive Radio, Vol. 11, No. 2, pp.174-185, April 2009.

•  C.Y. Jung, H.Y. Hwang, D.K. Sung, G.U. Hwang, “Enhanced Markov Chain Model and Throughput Analysis of the Slotted CSMA/CA of the IEEE 802.15.4 under an Unsaturated Traffic Condition,” IEEE Trans. On Vehicular Technology, Vol. 58, No. 1, pp.473-478, Jan. 2009.

• Y.W. Chung, M.Y. Chung, D.K. Sung, “Modeling and Analysis of Mobile Terminal Power On/Off State Management Considering User Behavior,” IEEE Trans. on Vehicular Technology, Vol. 57, No.6, pp.3708-3722, Nov. 2008.

• H. Jin, B.C. Jung, H.Y. Hwang, D.K. Sung, “A MIMO-Based Collision Mitigation Scheme in Uplink WLANs,” IEEE Communications Letters, vol. 12, No.6, pp.417-419, June 2008.

• H.Y. Hwang, S.J. Kim, D.K. Sung, N.O. Song, “Performance Analysis of IEEE 802.11e EDCA with a Virtual Collision Handler,” IEEE Trans. On Vehicular Technology, Vol. 57, No. 2, pp.1293-1297, March 2008.

• S.J. Kim, H.Y. Hwang, J.K. Kwon, D.K. Sung, “Saturation Performance Analysis of IEEE 802.11 WLAN under the Assumption of No Consecutive Transmissions,” IEICE Trans. On Communications, Vol. E90-B, No. 3, pp.700-703, March 2007.

(2) Conference Papers

• B.H. Jung, N.O. Song, and D.K. Sung, “An Energy-efficient WiFi Offloading Model in a Heterogeneous Network,” IEEE Online GreenCom 2014, Nov. 13, 2014.

• J.Y. Kim, N.O. Song, B.H. Jung, H.S. Leem, and D.K. Sung, “Placement of WiFi Access Points for Efficient Offloading in an Overlay Network,” IEEE PIMRC 2013, Sep. 2013.

• B.H. Jung, H. Jin, and D.K. Sung, “Adaptive Transmission Control and Rate Selection Scheme for Maximizing Energy Efficiency of IEEE 802.11 Stations,” IEEE PIMRC 2012, Sep. 2012.

• B.H. Jung, A. Usman, D.K. Sung, “Throughput, Energy Consumption, and Energy Efficiency of IEEE 802.15.6 Body Area Network (BAN) MAC Protocol,” IEEE PIMRC 2012, Sep. 2012.

• J. Cha, H. Jin, B.C. Jung, and D.K. Sung, “Performance Comparison of Downlink User Multiplexing Schemes in IEEE 802.11ac: Multi-user MIMO vs. Frame Aggregation,” IEEE WCNC 2012, April, 2012.

• H. Jin, J.Y. Cha, and D.K. Sung, “A Downlink and Uplink Collision Mitigation Scheme for Multi-User MIMO-Based WLANs Through Relaying,” Int. ICST Conference on Communications and Networking in China (CHINACOM 2011), Aug. 2011.

• J. Cha, H. Jin, and D.K. Sung, “Multi-channel CSMA/CA Based Smart Utility Networks,” 6th Int. ICST Conference on Communications and Networking in China (CHINACOM 2011), Aug. 2011.

• H.Y. Hwang, S.J. Kim, B.S. Kim, D.K. Sung, and S. Park, “Performance Analysis of Wireless LANs with a Backoff Freezing Mechanism,” Advanced Communication and Networking (ACN) 2011, vol. 199, pp.312-320, Aug. 2011.

• Ho Young Hwang, Sun-Jong Kwon, Yun Won Chung, Dan Keun Sung, and Suwon Park, "Steady State Analysis of an Energy Efficient Mobility Management Scheme in IP-Based Wireless Networks," FGIT 2010 (Future Generation Information Technology 2010), Dec. 2010.

• J.W. Chong, Y. Sung, D.K. Sung, “Multi-band CSMA/CA-Based Cognitive Radio Networks,” International Wireless Communications and Mobile Computing (IWCMC) Conference, June 2009.

• B.H. Jung, S.J. Kim, H.Y. Hwang, J.W. Chong, D.K. Sung, “Performance Improvement of Error-Prone Multi-Rate WLANs through Adjustment of Access/Frame Parameters,” IEEE ICC 2009, June 2009.

• J. Hu, B.C. Jung, H.Y. Hwang, D.K. Sung, “A Throughput Balancing Problem between Uplink and Downlink in Multi-User MIMO-based WLAN Systems,” IEEE WCNC 2009, April 2009.

• J.W. Chong, Y. Sung, D.K. Sung, “Analysis of CSMA/CA Systems under Carrier Sensing Errors: Throughput, Delay, and Sensitivity,” IEEE Globecom 2008, Dec. 2008.

• D.N. Ko, J.W. Chong, B.H. Jung, D.K. Sung, “Dynamic Clustering Schemes of ZigBee Networks in the Presence of WLAN Interference,” IEEE Milcom 2008, Nov. 2008.

• B.H. Jung, J.W. Chong, C.Y. Jung, S.M. Kim, D.K. Sung, “Interference Mediation for Coexistence of WLAN and ZigBee Networks, IEEE PIMRC, Sep. 2008.

• J.W. Chong, Y. Sung, D.K. Sung, “Cross-Layer Performance Analysis for CSMA/CA System: Impact of Imperfect Sensing,” IEEE Workshop on Signal Processing Advances for Wireless Communications, July 2008.

• H. Jin, B.C. Jung, H.Y. Hwang, D.K. Sung, “Performance Comparison of Uplink WLANs with Single-User and Multi-User MIMO Schemes,” IEEE WCNC 2008, March 2008.

• B.S. Kim, H.Y. Hwang, D.K. Sung, “Effect of Frame Aggregation on the Throughput Performance of IEEE 802.11n,” IEEE WCNC 2008, March 2008.

• J.W. Chong, H.Y. Hwang, C.Y. Jung, D.K. Sung, “Analysis of Throughput and Energy Consumption of a Zigbee Network in the Presence of Bluetooth Interference,” IEEE Globecom 2007, Dec. 2007.

• J.W. Chong, H.Y. Hwang, C.Y. Jung, D.K. Sung, “Analysis of Throughput in a Zigbee Network under the Presence of WLAN Interference,” 7th Int. Symposium on Communications and Information Technologies, Oct. 2007.

• S.M. Kim, J.W. Chong, B.H. Jung, M.S. Kang, D.K. Sung, “Energy-aware Communication Module Selection through Zigbee Paging for Ubiquitous Wearable Computers with Multiple Radio Interfaces,” Int. Symposium on Wireless Pervasive Computing 2007, Feb. 2007.

• B.H. Jung, J.W. Chong, S.H. Jeong, H.Y. Hwang, S.M. Kim, M.S. Kang, D.K. Sung, “Ubiquitous Wearable Computer (UWC)- Aided Coexistence Algorithm in an Overlaid Network Environment of WLAN and Zigbee Networks,”  Int. Symposium on Wireless Pervasive Computing 2007, Feb. 2007.

• M.S. Kang, J.W. Chong, H. Hyun, S.M. Kim, B.H. Jung, D.K. Sung, “Adaptive Interference-Aware Multi-Channel Clustering Algorithm in a Zigbee Network in the Presence of WLAN Interference,” Int. Symposium on Wireless Pervasive Computing 2007, Feb. 2007.

• S.M, Kim, J.W. Chong, B.H. Jung, M.S. Kang, and D.K. Sung, “Energy-Efficient module selection through Zigbee Paging for Ubiquitous Wearable Computers with Multiple Radio Interfaces,” Int. Symposium on Wireless Pervasive Computing 2007, Feb. 2007.

• M.J. Kim, B.C. Jung, J.W. Chong, D.K. Sung, “Performance Enhancement of a TH-PPM UWB System Using a Near-Interference Erasure Scheme in Multi-User Environments,” IEEE Int. Conference on UWB, September 2006.

• S.M. Kim, D.K. Sung, et al., “Experiments on Interference and Coexistence between Zigbee and WLAN Devices Operating in the 2.4GHz Band," Next Generation PC 2005 International Conference, Nov. 2005

• C.Y. Jung, Y.J. Hong, B.C. Jung, D.K. Sung, “Orthogonal Time Hopping Multiple Access for UWB Impulse Radio Communications,” APCC 2005, Oct. 2005.

• J.W. Chong, B.C. Jung, J.H. Chung, D.K. Sung, “Statistical Multiplexing Based Hybrid FH-OFDMA System for OFDM-Based UWB Indoor Radio Access Networks,” IEEE Int. Conference on Ultra-Wideband, Sep. 2005. 

• M.J. Kim, J.H. Chung, C.Y. Jung, J.W. Chong, D.K. Sung, “Link Performance Evaluation of a TH-PPM UWB System in the Presence of Multi-User Interference,” IEEE Int. Conference on Ultra-Wideband, Sep. 2005.  

• H.Y. Hwang, N.O. Song, D.K. Sung, N. Moayeri, “Effect of Carrier Sensing Range in a Network Architecture with a Multi-Sector Antenna Based Access Point and Omni-Directional Mobile Nodes,” APCC/MDMC 2004, Aug. 2004.

• H.Y. Hwang, N. Song, D.K. Sung, N. Moayeri, “Performance Evaluation of a Multi-Sector Antenna Based Access Point Network Architecture,” PIMRC 2003, Sep. 2003.

• Y.W. Chung and D.K. Sung, “Effect of Personal Mobility Management in Mobile Communication Networks,” IEEE VTC Fall, Sep. 2003.

• H.Y. Hwang, S.J. Kwon, Y.W. Chung, D.K. Sung, “A Mobility Management Scheme for Reducing Power Consumption in Wireless IP-Based Networks,” IEEE Globecom 2002, pp.2979-2983, Nov. 2002.

• S.M. Lee, H.Y. Hwang, D.K. Sung, “Group Mobility Management in Mobile Ipv6 Networks,” APCC 2002, pp.133-136, Sep. 2002.

• S.J. Kwon, S.Y. Nam, H.Y. Hwang, D.K. Sung, “Analysis of a Mobility Considering Battery Power Conservation in IP-Based Mobile Networks,” APCC 2002, pp.1-4, Sep. 2002.

• Y.W. Chung, M.Y. Chung, D.K. Sung, “Adaptive Management Scheme of Mobile Terminal State Information,” ICC2001, Vol. 9, pp.2814-2818, May 2001.

(3) Patents 

• D.K. Sung, B.H. Jung, and N.O. Song, “Method and Apparatus of Efficient Cellular Traffic Offloading through WLAN (무선랜 망을 이용한 효율적인 셀룰러 부하분산 (오프로딩)을 위한 장치 및 단말),” 10-1551563, Korea,  (10-2014-0015964, Korea, Feb. 12, 2014). Sep. 2, 2015.

• D.K. Sung, J.Y. Kim, N. Song, B.H. Jung, and H.S. Leem, “Method and System of Operating Multi-cell WiFi and WiFi Offloading for Solving Both the Hidden node Problem and Exposed Node Problem (은닉 노드 문제 및 노출 노드 문제를 해결한 다중 셀 와이파이 운용 및 와이파이 오프로딩 방법 및 시스템),” 10-1458299, Korea, ( 10-2013-0022280, Feb. 28, 2013), Oct. 29, 2014. 

• D.K. Sung, B.H. Jung, N. Song, “Method and Apparatus for WiFi Offloading Using WiFi Network in a Cellular and WiFi Overlay Network and Device Enabling the Method (무선랜 망을 이용한 셀룰러 부하 분산 방법 및 장치 및 이를 이용한 단말),” 10-1447354, Korea, (10-2013-0022276, Feb. 28, 2013), Sep. 26, 2014.

• D.K. Sung, B.H. Jung, J.W. Chong, S.M. Kim, D.N. Ko, C.K. Cho, “Method of Avoiding Collision between Zigbee Communication System and Other Communication System (지그비 통신에서 통신 시스템간 충돌 회피 방법 및 장치),” 10-1427980, Korea, (1020080017761 (2008.02.27)), Aug. 1, 2014.

• D.K. Sung, B.C. Jung, H. Jin, H.Y. Hwang, “Scheduler and Scheduling Method for Transmitting Data in MIMO Based Wireless LAN Systems,” US2014 0161109 A1, USA (US 14/179,976, Feb. 13, 2014), June 12, 2014. 

• D.K. Sung, B.C. Jung, H. Jin, H.Y. Hwang, “Scheduler and Scheduling Method for Transmitting Data in MIMO Based Wireless LAN Systems,” US8675510 B2, USA, ( US 12/582,164, USA, Oct. 2009) March 18, 2014, 

• D.K. Sung, B.H. Jung, H. Jin, “Method of Operating Terminals and Access Point to Maximize Energy Efficiency of Wireless Local Area Network (무선 로컬 영역 네트워크의 에너지 효율을 극대화하는 단말 및 액세스 포인트의 동작 방법),” 10-1341669, Korea, (1020120042643 (2012.04.24)), Dec. 9, 2013. 

• D.K. Sung, B.C. Jung, “Method of Selecting Antennas and Transmitting Data in Multi-Input Multi-Output Wireless Local Area Network Environments,” US8279744 B2, USA, (US 12/599,463, May 9, 2008), Oct. 2, 2012. 

• D.K. Sung, J.W. Yang, B.H. Jung, “Wireless Communication Method and Apparatus for Mitigating a Hidden Node Problem (히든 노드 문제를 완화시키기 위한 무선 통신 방법 및 장치),” 10-1062340, Korea, (1020090049305 (2009.06.04)), Aug. 30, 2011. 

• M. Park, D.K. Sung, B.C. Jung, H. Jin, H.Y. Hwang, “Scheduler and Scheduling Method for Transmitting Data in MIMO Based Wireless LAN Systems (다중 사용자 다중 입출력 기반의 무선랜 시스템에서 데이터전송 스케줄러 및 데이터 전송 스케줄링 방법),”1041681, Korea, (1020080104313 (2008.10.23) ),  Jun. 8, 2011 

• D.K. Sung, Y. Sung, J.W. Chong, “Wireless Network Systems with Priority Class Based Medium Access Control (우선순위 기반의 매체접속방식의 무선 네트워크 시스템, 무선 네트워크 통신 방법),” 10-1040290, Korea, (1020080122361 (2008.12.04)), Jun. 2, 2011. 

• D.K. Sung, D.N. Ko, J.W. Chong, “Method of Configuring Clustered Wireless Sensor Networks and Clustered Wireless Networks (클러스터 센서 네트워크의 클러스터 구성방법 및 상기 방법이 적용된 센서 네트워크),” 10-1024038, Korea, (1020080106345 (2008.10.29)), March 15, 2011.

• D.K. Sung, D.N. Ko, J.W. Chong, “Method of Avoiding Interference and Reclustering Method of Clustered Wireless Sensor Networks and Wireless Sensor Communication Apparatus Applied Thereto (클러스터 구조의 센서 네트워크의 간섭 회피 방법, 클러스터 재구성 방법 및 상기 방법이 적용된 센서 네트워크 통신장치),” 10-0999046, Korea, (1020080106344 (2008.10.29)), Dec. 1, 2010. 

• D.K. Sung, B.C. Jung, H. Jin, H.Y. Hwang, “Apparatus and Method for Determining Minimum Contention Window Size in Multi-User MIMO WLAN Systems, (다중 사용자 다중 입출력 기반의 무선랜 시스템에서 경쟁 시간 구간의 최소값을 결정하는 장치 및 방법)” 10-0988145, Korea, (1020080104314 (2008.10.23)), Oct. 8, 2010. 

• D.K. Sung, B.C. Jung, H. Jin, H.Y. Hwang, “Apparatus and Method for Determining Minimum Contention Window Size in Multi-User MIMO Based WLAN Systems,” US2010 0103913 A1, USA, (US 12/582,190, Oct. 20, 2009), April 29, 2010. 

• H. Jin, H.Y. Hwang, B.C. Jung, D.K. Sung, “Scheduling for a MIMO Wireless LAN System.” EP2180628 A2, EU, (EP20090173781, Oct. 22, 2009), April 28, 2010. 

• D.K. Sung, B.C. Jung, H. Jin, H.Y. Hwang, “Method for Transmitting and Receiving Data in Multiple-Input-Multiple-Output Wireless Local Area Network Environment, a System and Apparatus for Performing the Method,” EP2104292 A1, EU, (EP20080153091,  08153091.7-2415(pending), EP, March 20, 2008), Sep. 23, 2009. 

• D.K. Sung, B.C. Jung, Jin Hu, H.Y. Hwang, “Method of Transmitting and Receiving Data in Multi-Input Multi-Output Wireless Local Area Network Environment, and a System and Apparatus for Performing the Method,” US2009 0225876, USA, (US 12/043,354,  March 6, 2008)  Sep. 10, 2009. 

• D.K. Sung, S.J. Kim, and H.Y. Hwang, “Wireless LAN Apparatus Based on Multiple MAC Entities (다중 ＭＡＣ실체 기반의 무선 랜 장치),” 10-0896064, Korea, (1020070059503 (2007.06.18) ), April 27, 2009.

• D.K. Sung, B.C. Jung, “Method of Selecting Antennas and Transmitting Data in Multi-Input Multi-Output Wireless Local Area Network Environment (다중입력 다중출력 무선 랜 환경에서 안테나를 선택하여 데이터를 전송하는 방법) ,” 10-0895576, Korea, (1020070045848 (2007.05.11) ), April 22, 2009. 

• D.K. Sung, H.Y. Hwang, S.J. Kim, B.C. Jung, H. Jin, “Wireless LAN Apparatus Based on Multiple Queues (다중 큐 기반의 무선 랜 장치),” 10-0853695, Korea, (1020070039300 (2007.04.23)), Aug. 18, 2008.

• D.K. Sung, B.C. Jung, Jin Hu, H.Y. Hwang, “Method of Transmitting and Receiving Data in Multi-Input Multi-Output Wireless Local Area Network Environment (다중입력 다중출력 무선 랜 환경에서 데이터를 송수신하는 방법),” 10-0818630, Korea, (1020060097537 (2006.10.04)), March 26, 2008. 

• D.K. Sung, M.S. Kang, J.W. Chong, B.H. Jung, S.M. Kim, C.Y. Jung, “Method of Avoiding Interference for Zigbee Network and Zigbee Communication Apparatus Applied Thereto (지그비 네트워크의 간섭 회피 방법 및 상기 방법이 적용된 지그비 통신 장치),” #10-0767332, Korea,  (1020060133034 (2006.12.22) ), Oct. 9, 2007.

• D.K. Sung, M.S. Kang, J.W. Chong, B.H. Jung, S.M. Kim, C.Y. Jung, “Method of Avoiding Interference for Zigbee Network and Zigbee Communication Apparatus Applied Thereto (지그비 네트워크의 간섭 회피 방법 및 상기 방법이 적용된 지그비 통신 장치),” #10-0767332, Korea,  (1020060133034 (2006.12.22)), Oct. 9, 2007. 

• D.K. Sung, M.J. Kim, C.Y. Jung, J.W. Chung, S.H. Jeong, S.M. Kim, Y.J. Kang, “Association Method for Multiple Devices in Wireless Personal Area Networks 무선 개인지역망에서 다수 디바이스의 피코넷 등록 방법 )(,” 10-0758828, Korea, (1020050135174 (2005.12.30) ), Sep. 10, 2007.

• D.K. Sung, S.M. Kim, J.W. Chung, C.Y. Jung, M.J. Kim, Y.J. Kang, S.H. Jeong, “Apparatus and Method for Determining and Avoiding Co-Channel Interference in Wireless Personal Area Networks(무선개인지역망에서 같은 대역을 사용하는 이종통신시스템의 공존을 위한 간섭 판단 및 회피 방법 및 장치),” 10-0728356, Korea, (1020050135144 (2005.12.30)), June 7, 2007.