Kwang-Ryul Jung

Machine-Type-Communication (MTC) Device Grouping Algorithm for Congestion Avoidance of MTC Oriented LTE Network

Machine-Type-Communication (MTC) is a new paradigm in mobile wireless network domains such as Mobile WiMAX (IEEE 802.16e) and 3GPP LTE (3rd Generation Partnership Project Long Term Evolution). We explain the background for MTC environments, and its key issues. Then we focus on the uplink traffic aggressiveness characteristics in major applications such as Smart Grid. Then, we propose a new congestion avoidance algorithm to reduce the congestion of the uplink intensive applications.

Consideration of UMTS-WLAN seamless handover

By mutual complemented reason of wide coverage and high data transmission, the integration and handover of SG network and WLAN is regarded as an important function for 3G beyond (B3G) mobile communication systems. The seamless mobility is one of the basic requirements for handover between these heterogeneous networks. In this paper, we present a seamless handover mechanism for UMTS and WLAN within the framework of handover architecture, IP mobility and authentication mechanism. Firstly, we review the 3GPP-specific integration architecture of UMTS and WLAN, WLAN UE-initiated tunnel mechanism, IP mobility and authentication mechanisms of both networks. Then we propose the configuration of mobile IPv6 based UMTS-WLAN overlay network and the security mechanism for reducing the handover delay. Lastly we show the operation of seamless handover in our proposed network model.

Design of Session and Bearer Control Signaling in 3GPP LTE System

3GPP long term evolution (LTE) system targets a packet optimized system which provides higher data rate and lower delay with improved coverage and spectrum efficiency. The LTE system requires optimized signaling as well as optimized radio transmission and radio access network. Key LTE system features related to signaling optimization have been proposed in 3GPP and these should be considered in designing the LTE signaling protocols. In this paper, we propose an LTE radio interface signaling for session and bearer control, which adopts key LTE features agreed in 3GPP such as network-controlled service, QoS aggregation, and default IP access service. We analyze the session setup delay with the proposed signaling. The session setup delay is much reduced when compared to the pre-LTE signaling.

Development of device-to-device communication in LTE-Advanced system

Device-to-Device communication in 3GPP LTE-Advanced cellular network has been proposed as a means to provide high data rate, low delay, and low power consumption for mobile consumer equipments. In this paper, we propose an enhanced LTE-advanced system which incorporates the D2D communication, and describe the experimental result to show the feasibility of the D2D technology.

Design and implementation of a radio resource control protocol in WCDMA using SDL

In wideband code division multiple access (WCDMA), most of the control signalling between mobile terminal (ie, user equipment) and base station (ie, radio network controller) is made up of messages of the radio resource control (RRC) protocol. The Specification and Description Language (SDL) development of a WCDMA RRC protocol is presented. SDL is a high abstraction level system design language with a clear graphic notation.

Definitive Link Layer Triggers for Predictive Handover Optimization

Main idea of Fast MIPv6 (FMIPv6) is the new address pre-configuration on the link of the current access router by the aid of predictive link layer triggers. If the link layer triggers are not available prior to the link layer handover, the FMIPv6 reverts to the reactive mode. In this case, the MN performs the address configuration after connecting to the new access router. It causes additional packet loss and signaling overhead. Also, too early link layer triggers increase the service delay time and the buffer space. In this paper, we propose the definitive link layer triggering criterion to support the predictive handover in FMIPv6. We consider the handover scenario from WLAN to a cellular network which is most common access networks in wireless worlds. To provide the best time on which the link layer triggers initiate, we introduce a remaining link lifetime which considers the received signal strength variation rate. The performance evaluation shows that the proposed algorithm substantially reduces the handover latency with guaranteeing the predictive mode FMIPv6.

Sink-Independent Model in Wireless Sensor Networks

Wireless sensor networks generally support users that send queries and receive data via the sinks. The user and the sinks are mostly connected to each other by infrastructure networks. The users, however, should receive the data from the sinks through multi-hop communications between disseminating sensor nodes if such users move into the sensor networks without infrastructure networks. To support mobile users, previous work has studied various user mobility models. Nevertheless, such approaches are not compatible with the existing routing algorithms, and it is difficult for the mobile users to gather data efficiently due to their mobility. To improve the shortcomings, we propose a view of mobility for wireless sensor networks and propose a model to support a user mobility that is independent of sinks.