• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.700-702
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• 2001

As computers and networks become popular, distributing information on the Interment is common in our daily life. Also, the explosion of the Internet, of wireless digital communication and data exchange on Internet has rapidly changed the way we connect with other people. But secure mall is gamins popularity abroad and domestically because of their nature of prodding security. That is. it has been used a variety of fields such as general mail and e-mail for advertisement But, As the data transmitted on network can be easily opened or forged with simple operations. Most of existing e-mall system don't have any security on the transmitted information. Thus, security mail system need to provide security including message encryption, content integrity, message origin authentication, and non-repudiation. In this paper, we design implement secure mall system with non-repudiation service and encryption capability to provide services for certification of delivery and certification of content as well as the basic security services.

• Journal of KIISE:Information Networking
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• v.36 no.4
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• pp.330-338
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• 2009

Various applications based on the location information of things are developed as entering by the ubiquitous computing age. Wireless sensor networks are suitable to indoor location-based service because of the important features such as low-power consumption, low-cost, easy deployment, etc. To recognize the distance between nodes, the indoor location-based system transmits both ultrasound signal and radio signal periodically. However, increment of the number of deployed sensor nodes make lots of collision and interference among the signals and it can degrade the accuracy of location-based system. In this paper, we propose a beacon management mechanism to increase the probability of transmission chance to the nearest beacon from the listener. It can minimize collision and interference and reduce the error probability due to the characteristics of ultrasound.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.438-440
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• 2010

As market expansion and demand for smart phone have increased, the wireless data trafic is rapidly growing now. To solve this problem, common carriers in Korea distribute the trafic over Wi-Fi. Smart phones have multi interfaces such as 3G radio, Wi-Fi, Bluetooth, and etc and can utilize them. However these interfaces support seamless handover between not different interfaces but same interfaces, so that users couldn't be supported continuity for handover. In this paper, we describe the Media Independent Handover(MIH) services that is proposed by IEEE 802.21. The standard enhance the handovers across heterogeneous access networks and to optimize the service continuity during handovers.

• Electronics and Telecommunications Trends
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• v.34 no.6
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• pp.51-60
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• 2019

As a way to further expand and enable the 5G ecosystem, the $3^{rd}$ Generation Partnership Project (3GPP) is considering the development of a 5G new radio (NR)-based non-terrestrial network (NTN). These NTNs are expected to provide ubiquitous 5G services to user's equipment (especially, in Internet of Things/machine-type communications (IoT/MTC) public safety, and critical communications) by extending service coverage to areas not covered by 5G terrestrial networks. To this end, this NTN is developing scenarios to provide 5G services using spaceborne vehicles, such as geosynchronous and low-Earth orbit satellites, and airborne vehicles, such as unmanned aircraft systems, including high-altitude pseudo-satellites. In addition, various technologies are being studied to satisfy new requirements not considered in 5G NR, such as long propagation delay time, large cell coverage, large Doppler effect, and base station movement. In this paper, we present the scenarios, requirements, technical issues and solutions, and standardization planning for NR-based NTN in 3GPP.

• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.271-280
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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. Finally, simulation results are presented to show the improved performance over the data throughput, handover success rate, the system service cost and handover attempt number.

• The Transactions of the Korea Information Processing Society
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• v.4 no.7
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• pp.1804-1820
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• 1997

In this paper, an efficient call control procedure is presented for next generation wireless ATM networks and its performance is mathematically analyzed using the open queueing network. This procedure is based on a new scheme called as the cell clustering. When we use the cell clustering scheme, at the time that a mobile connection is admitted to the network, a virtual cell is constructed by choosing a group of neighboring base stations to which the call may probabilistically hand over and by assigning to the call a collection of virtual paths between the base stations. Within a microcell/picocell environment, it is seen that the cell clustering can support effectively a very high rate of handovers, provides very high system capacity, and guarantees a high degree of frequency reuse over the same geographical region without requiring the intervention of the network call control processor each time a handover occurs. But since mobiles, once admitted, are free to roam within the virtual cell, overload condition occurs in which the number of calls to be handled by one base station to exceed that cell site's capacity of radio channel. When an overload condition happens, the quality of service is abruptly degraded. We refer to this as the overload state and in order to quantify the degree of degradation we define two metrics, the probability of overload and the normalized average time spent in the overload state. By using the open network queueing model, we derive closed form expressions for the maximum number of calls that can be admitted into the virtual cell such that the two defined metrics are used as the acceptance criteria for call admission control.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2507-2517
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• 2015

In this research, we aim to analyze the trend of Huawei's PCT patent applications. As a result of analyzing Huawei's PCT patents by dividing temporal spans into three periods - the early 2000s, the late 2000s, and the early 2010s -, the following characteristics have been observed. First, the number of PCT patent applications has conspicuously increased from the early 2000s to the late 2000s and this trend has continued during the early 2010s. Second, in terms of a core technological field, whereas Huawei focused on the development of technologies in the 'H04L: transmission of digital information' sector during the early/late 2000s, it changed this field to the 'H04W: wireless communication networks' sector during the early 2010s. Lastly, in the case of the patent maps, it was found that while general communications technologies, as expressed with such keywords as 'user' and 'network,' were actively developed during the early/late 2000s, mobile phone-related technologies grasped this leading position, as shown with the keywords including 'user equipment,' 'base station,' and 'MME,' during the early 2010s. It was also noticeable that Huawei filed LTE-related patent applications more actively than Apple and Samsung Electronics, which implies that it will presumably pioneer the global market more aggressively than its competitors in the future.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.12
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• pp.45-51
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• 2010

The main issue in mobile cloud computing is how to support a seamless service to a mobile mode. Mobile IPv6 (MIPv6) is a mobility supporting protocol which is standardized by the Internet Engineering Task Force (IETF). Mobile IPv6 fast handovers (FMIPv6) is the extension of MIPv6 which is proposed to overcome shortcomings of MIPv6. Recently, fast handovers for Mobile IPv6 over IEEE 802.16e which is one of broadband wireless access systems has been proposed by the IETF. It was designed for supporting cross-layer fast handover. In this paper, we propose an enhanced cross-layering mobile IPv6 fast handover over IEEE 802.16e networks. In our scheme, a new access router generates a new address for the mobile node by using a layer 2 trigger. We utilize a layer 2 message which is sent from a new base station to the new access router in order to inform the new access router of information of the mobile node. A previous access router sends a binding update message to the mobile node's home agent when it acquires the new address of the mobile node. We evaluate the performance of the proposed scheme compared with the existing schemes in terms of the signaling cost and the handover latency. From the results, we observe that the proposed scheme can support fast handover effectively over IEEE 802.16e networks than existing schemes.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.18-26
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• 2012

As the performance of the next-generation broadband wireless networks is dramatically enhanced, various services (i.e., education, video conferencing, online games, etc.) have been provided to users through a smart mobile platform. Since those services are usually provided by using the centralized architecture, it is difficult for a lot of users to provide the scalable communication service with regard to traffic management. To solve these problems, we have proposed an architecture of P2P-based group communication management scheme using smart mobile device. More specifically, we design the group management protocol and algorithm for the group member management and the traffic management. By using these methods, the mobile multimedia streaming service can be provided with scalability. In order to verify the performance of the proposed scheme, we have mathematically analyzed the performance in terms of the average transmission delay and bandwidth utilization.

• The KIPS Transactions:PartC
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• v.14C no.3 s.113
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• pp.255-266
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• 2007

RSVP (Resource reSerVation Protocol) is the Internet standard protocol for supporting QoS (Quality of Service) requirements by reserving network resources between the sender and the receiver. Several problems, such as common path identification and resource pre-reservation, should be solved to apply RSVP in wireless mobile environments. To resolve these problems, this paper proposes DBRA (Dynamic Branch Router Approach) based on two designated entities, candidate access routers and a branch router. While several RSVP sessions between a branch router and candidate routers are managed, DBRA makes use of only one RSVP session between the sender and a branch router. Based on a network simulation, the proposed scheme has been compared with MRSVP (Mobile RSVP) and HMRSVP (Hierarchical MRSVP) in terms of the average packet transmission rate, bandwidth utilization and RSVP session failure rate.