The main research topics of network laboratory are wireless networks, wireless MAC, IP Qos and network security.
* Wireless Network : Various data services are at close hand owing to the growth of Internet and the evolution of wireless techniques. Nowadays we use wireless Internet by notebooks, PDAs, and cellular phones through the cellular data networks such as WiBro (IEEE 802.16). Some service providers are expected to deploy the fourth generation wireless systems integrating voice and data services above 20Mbps rate. The fourth generation systems have already drown the attention of many researchers. The wireless system has very limited resources such as power, bandwidth and processing power, which necessitates managing them efficiently to provide the acceptable QoS and fairness. Therefore, we focus on resource management, mobility management, integrated-network management and so on.
* Wireless MAC : Different from the wired environment, wireless medium is shared to all the devices in the network. For example, in the wired network, if one node transmits a signal to the wire, only the nodes connected to the wire can detect the signal. On the other hand, in the wireless network, if one node transmits a signal to the wireless medium, every nodes in the network can detect the signal. Moreover, the transmitted signal can interfere in the communication of other nodes. The wireless medium access control (MAC) prevents these collisions and make wireless nodes share limited wireless resources fairly. Good wireless MAC protocol can improve the throughput in addition to the fairness. Therefore, we focus on improving many wireless protocols such as wireless LAN, sensor network, adhoc network and power line communications.
* IP Qos : We are interested in promoting protocol of each layer in order to enhance overall network performance. In theoretical study, we perform analysis the network protocols and modify them. The modification based on the analysis is evaluated through simulation. In experimental study, we implement both the existing network protocol and our proposal, and compare their performance through laboratory tests.
* Security : The rate of DoS attack is increasing for that the DoS attack is easy to launch without any efforts to penentrate into the system but it's difficult to prevent and to do the forensic analysis to find the right attacker.
So the Internet service providers are forced to develop and provide some effective methodology to prevent this kinds of DoS attacks.
Therefore we do research to find a way to secure the victim's system from DoS attacks fundamentally and to detect possible attacks effectively by monitoring some abnomal traffic patterns.
Research Interests & Projects
Journals & Patents
 Sangkyu Park, Chan-Byoung Chae, and Saewoong Bahk,
"Large-scale Antenna Operation in Heterogeneous Cloud Radio Access Networks: A Partial Centralization Approach,"
IEEE Wireless Communications Magazine, vol. 22, issue. 3, pp. 32-40, June 2015
 Changwon Nam, Changhee Joo, and Saewoong Bahk,
“Joint Subcarrier Assignment and Power Allocation in Full-Duplex OFDMA Networks,”
IEEE Transactions on Wireless Communications, vol. 14, issue. 6, pp. 3108-3119, June 2015
 Seowoo Jang and Saewoong Bahk,
“A Channel Allocation Algorithm for Reducing the Channel Sensing/Reserving Asymmetry in 802.11ac Networks,”
IEEE Transactions on Mobile Computing, vol. 14, issue. 3, pp. 458-472, Mar. 2015
 Taeseop Lee, Sangkyu Park, Hyung-Sin Kim and Saewoong Bahk,
“Sounding resource management for QoS support in massive MIMO systems,”
Computer Networks, vol. 70, pp. 142-153, Sep. 2014
 Daeho Kang, Sangkyu Park, Changhee Joo, and Saewoong Bahk,
“Address-Free Contention in Wireless Access Networks with Common Control Channel for Throughput Improvement,”
Computer Networks, vol. 64, pp. 112-124, May 2014
 Sunheui Ryoo, Changhee Joo, Saewoong Bahk,
"Location-based Spectrum Allocation and Partitioning Scheme for Cross-tier Interference Mitigation in Macro-Femtocell Networks,"
Computer Networks, vol. 57, issue. 15, pp. 2869-2879, Oct. 2013
 Jongwook Lee and Saewoong Bahk,
"On the MDP-based Cost Minimization for Video-on-Demand Services in a Heterogeneous Wireless Network with Multi-Homed Terminals,"
IEEE Transactions on Mobile Computing, vol. 12, issue. 9, pp. 1737-1749, Sep. 2013