• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3B
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• pp.144-151
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• 2008

In this paper, we propose a video streaming server that guarantees a certain level of quality when a server should serve video streaming service to multiple heterogenous clients simultaneously with TCP transport. If each heterogeneous client requests video streaming service in according to its own requirement such as bitrate of content and these requests are accepted by a server, then TCP flows for each video streaming session fairly share limited uplink bandwidth of the server. At this time, because TCP's bandwidth fair-share characteristics can result in bandwidth shrinkage of higher bitrate video streaming session, the client of higher bitrate video may suffer sluggish playback which is related with streaming QoS degradation. To tackle this problem, our proposed server system uses multiple TCP connections adaptively for each video streaming session depending on the anticipated status of the client playout buffer. Simulation results show that our proposed algorithm can successfully reduce the occurrence of playout buffer underrun and enhance streaming quality for whole video clients.

• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.57-66
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• 2012

LTE-Advanced network will form the high-speed IP backbone in collaboration with heterogeneous radio access networks for dynamic optimized resource utilization. In order to implement more innovative and attractive services such as U-Cloud streaming, LBS and mobile smart TV, a mobile terminal needs to support multiple sessions simultaneously. Efficient resource allocation schemes are necessary to maintain QoS of multiple sessions because service continuity may be defected by delay and information loss during handover. This paper proposes a resource allocation scheme to accommodate multiple sessions in a mobile terminal on handover period based on session priority mechanism. Simulation is focused on the forced termination probability of handover sessions. Simulation results show that our proposed method provides a better performance than the conventional method.

• Management & Information Systems Review
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• v.32 no.3
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• pp.247-261
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• 2013

Recently, the smart phone, a carrying along terminal connection technology such as Galaxytap/iPad etc. evolves, and supply is increasing rapidly, is included for smart phone because various sensor technologies are developed and service application that is acted in terminal with this is accompanied and grow. Continuously 4 generation to 3 Gs, Wibro Wireless network technology of communications a LTE technology from that is constructed, environment for Ubiquitous realization is being constructed fast. Therefore, in this paper it can inquire state of electronic, furniture devices through apartment complex web server and gear that control groove network at smart phone, and control, and confirms home state prevention of crimes state, and video inquiry of position that CCTV is placed in apartment complex was available. And it proposed integrated smart apartment with parking system and medical system using RFID system in ubiquitous environment.

• Journal of Broadcast Engineering
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• v.15 no.5
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• pp.632-641
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• 2010

This paper shows the research about the personalized broadcasting system. The personalized broadcasting is the service that users only show the programs which they want to watch when they want to watch these. The purpose of the bi-directional broadcasting service is supporting more satisfied and more personalized services by permitting the bi-directional data transformation. This research also develops the user profiling system for the bi-directional and personalized broadcasting service. This system applied the TV-Anytime metadata specifications which is the standard for the personalized broadcasting services, the system supports the various functions for the bi-directionl and personalized broadcasting such as the user profiling, contents metadata and targeting advertisement services. The bi-directional and personalized broadcasting system increases the users' satisfaction with the recommendation and management of the personally favorite broadcasting contents and advertisements, the trial run results show that the services raise the users' satisfaction with the intelligent and discriminating broadcasting services.

• The Journal of the Korea Contents Association
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• v.8 no.4
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• pp.71-78
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• 2008

We propose the scheme that supports continuously service when a user tries to contact new target network in broadband convergence network even though the network resource for the service is not enough. The proposed scheme transforms original service capacity into suitable QoS for the target network using the scalable service techniques in the oncoding/decoding and supports handover for the user. We analyzed the handover blocking probability of two schemes using queueing system to show the improvement of performance by the proposed scheme. Subsequently, we showed that the handover blocking probability in the proposed scheme is lower than that in the existing scheme.

• Journal of Internet Computing and Services
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• v.11 no.1
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• pp.35-48
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• 2010

For the next generation mobile communication system, diverse wireless network techniques such as beyond 3G LTE, WiMAX/WiBro, and next generation WLAN etc. are proceeding to the form integrated into the All-IP core network. According to this development, Beyond 3G integrated into heterogeneous wireless access technologies must support the vertical handover and network to be used of several radio networks. However, unified management of each network is demanded since it is individually serviced. Therefore, in order to solve this problem this study is introducing the theory of Common Radio Resource Management (CRRM) based on Generic Link Layer (GLL). This study designs the structure and functions to support the vertical handover and propose the vertical handover algorithm of which policy-based and MCDM are composed between LTE and WLAN systems using GLL and CRRM. Finally, simulation results are presented to show the improved performance over the data throughput, handover success rate and the system service cost.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12C
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• pp.1020-1028
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• 2010

Relay has attracted great attention due to its inherent capability to extend the service coverage and combat shadowing in next generation mobile communication systems. So far, most relay technologies have been developed under the half-duplex (HD) constraint that prevents relays from transmitting and receiving at the same time. Although half-duplex relay (HDR) is easy to implement, it requires partitioning of resource for transmission and reception, reducing the whole system capacity. In this paper, we propose a multinser precoding and power control scheme with sum rate matching for a full-duplex (FD) multiple-input multiple-output (MIMO) relay. Full-duplex relay (FDR) can overcome the drawback of HDR by transmitting and receiving on the same frequency at the same time, while it is crucial to reduce the effect of self-interference that is caused by its own transmitter to its own receiver. The proposed precoding scheme cancels the self-interference of the FDR as well as to support multiuser MIMO. Moreover, we suggest a power allocation scheme for FD MIMO relay with the constraint that the sum rate of the relay's received data streams is equal to that of the relay's transmit data streams.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11A
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• pp.1051-1058
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• 2010

Mobile IP (MIP) and SIP are considered as important technologies to provide the macro mobility in the next generation mobile convergence networks which have heterogeneous access networks. Typically, MIP and SIP are more suitable for the non-real-time TCP connections and the real-time RTP/UDP sessions respectively, hence a handset which uses both of these sessions should simultaneously apply MIP and SIP to perform the efficient mobility management. Existing multi-layered mobility management schemes focus on the signalling order of each protocol. However, simple combining of two protocols cannot provide the performance enhancement of the mobility management. In this paper, a novel multi-layered mobility management algorithm using the combination of SIP and fast MIPv6 (FMIPv6) is proposed. FMIPv6 and SIP mobility is simultaneously performed to reduce the service interrupt time and to guarantee QoS requirement. The delay model is defined to analysis the performance of the algorithm and the simulation results show the performance of the proposed algorithm.