Gyusun Yi’s scientific contributions

In this paper, we suggest about MIH (Media Independent Handover) supporting fully distributed handover in heterogeneous network based on Open vSwitch and OpenFlow. Although, personal mobile devices which are released recently have more than 2 mobile network interfaces, there is a small chance to utilize them simultaneously. To do this, MIH is suggested to guarantee the quality of application service when terminals of service users move to the other feature of wireless network in heterogeneous wireless network environment. Also, Open vSwitch of software type of various factors in SDN (Software Defined Network) and OpenFlow which has a control function by interacting with Data Path on network switch have arisen as a proposal to utilize wireless interfaces. Thus, in this paper, we experimented changes in packet flow of wireless interfaces. Moreover, we suggest a method of MIH based on SDN to guarantee communication quality of devices which uses more than 2 wireless interfaces.

Google proposed the new application-layer protocol named SPDY with the purpose of complementing problems of HTTP/1.1 to improve web speed. In this paper we evaluate the SPDY protocol’s performance in a variety ofmobile environment to examine the characteristics of the SPDY protocol and compare the differences between the existing protocol and SPDY protocol. Also through this performance evaluation, we analyze the problem of SPDY and propose directions for improvement of this protocol.

IEEE 802.11 WLAN is being considered to handle rapidly growing mobile data requirements. IEEE 802.11 WLAN providing faster data rates than cellular, but mobility is not considered. In this paper, I propose that based on received from Around AP network information, selects candidate access AP networks and make-before-break handover WiMAX. Proposed scheme was evaluated in real environment which consists of WLAN Aps, Mobile WiMAX, and the performance of TCP throughput by moving devices to over time. The average TCP throughput of the proposed measures is 6.49 Mbps, and it showed approximate 40 % improvement by comparing conventional measures TCP throughput 9.04 Mbps.