• Journal of KIISE:Information Networking
• /
• v.32 no.2
• /
• pp.254-260
• /
• 2005

In the guaranteed service, a real-time scheduling algorithm must achieve both high level of network utilization and scalable implementation. Here, network utilization indicates the number of admitted real-time sessions. Unfortunately, existing scheduling algorithms either are lack of scalable implementation or can achieve low network utilization. For example, scheduling algorithms based on time-stamps have the problem of O(log N) scheduling complexity where N is the number of sessions. On the contrary, round-robin algorithms require O(1) complexity. but can achieve just a low level of network utilization. In this paper, we propose a scheduling algorithm that can achieve high network utilization without losing scalability. The proposed algorithm is a Hierarchical Round-Robin (H-RR) algorithm that utilizes multiple rounds with different interval sizes. It provides latency bounds similar to those by Packet-by-Packet Generalized Processor Sharing (PGPS) algorithm using a sorted-Priority queue. However, H-RR requires a constant time for implementation.

• Journal of KIISE:Information Networking
• /
• v.30 no.3
• /
• pp.307-315
• /
• 2003

This paper proposes a Multicast Tree Extension (MTE) scheme for multicast in IP-based wireless networks. If a group receiver Joins a multicast group in a visited foreign network, multicast service may be disrupted when the foreign network does not have a multicast router. To avoid disruption, our scheme creates a bi-directional tunnel between the previous foreign agent (FA) and new foreign agent, if a mobile node (MN) moves from a foreign network with multicast capability to another foreign network with non-multicast capability. The MN thus continues to receive the multicast packets through the tunnel from the previous FA. Our scheme can avoid a long latency due to a long tunneling for group membership as well as multicast service disruption, even if the MN enters foreign networks with non-multicast capability. Simulation results show that our scheme offers lower costs for multicast delivery, tunneling and handoff latency than the existing scheme.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.48 no.1
• /
• pp.84-91
• /
• 2011

To develop the new network, the future network architecture is studied. Since the mobile devices are also advanced, they need for the mobility protocols. The one of the protocols, Fast handovers for proxy MIPv6(PFMIPv6) has studied by the Internet Engineering Task Force(IETF). Since PFMIPv6 adopts the entities and the concepts of fast handovers for MIPv6(FMIPv6) in proxy MIPv6(PMIPv6), it reduces the packet loss. Although the conventional scheme has proposed that it cooperated with an Authentication, Authorization and Accounting (AAA) infrastructure for authentication of a mobile node in PFMIPv6, it has the drawbacks such as high signaling cost and long handover latency. To reduce the signaling cost and the handover latency, we propose an enhanced authentication scheme in Fast handover for Proxy MIPv6. The proposed scheme reduces the handover latency and the signaling cost because the registration procedure and the authentication procedure are simultaneously performed. We also compare the proposed scheme with the conventional scheme in terms of the signaling cost and the handover latency.

• Proceedings of the IEEK Conference
• /
• 2004.06a
• /
• pp.253-256
• /
• 2004

A new multicast scheme for mobile nodes is proposed to support real-time communication in a more efficient way. In the proposed multicast scheme, the Explicit multicast (Xcast) is integrated with the Session Initiation Protocol (SIP). The proposed scheme reduces unnecessary network traffic and achieves low latency of packets in the network.

• Proceedings of the KAIS Fall Conference
• /
• 2011.12b
• /
• pp.668-670
• /
• 2011

본 논문에서는 고속 무선 데이터 전송을 위하여 멀티버스 구조 및 유연적인 데이터 버퍼시스템을 갖는 향상된 바이너리 CDMA에 시스템 설계에 관한 것이다. 개선된 바이너리 CDMA 시스템 구조는 제한된 리소스에서 시스템 버스의 Latency를 최대한 줄이고 고속 무선 데이터 전송을 위하여 버퍼접근구조를 변경하여 데이터 throughput을 향상하였다.

• Proceedings of the IEEK Conference
• /
• 2001.06a
• /
• pp.249-252
• /
• 2001

This paper focuses on the consideration of not only QoS parameters in wired network, but also QoS parameters in wireless network that supported for the Efficient QoS in the Al1 Service Levels. So, We supposed the "Efficient QoS Model" that guaranteed the QoS parameters "Loss Profile" , "Service Degradation" , "Latency and Jittering" , "Mobility of Mobile User" , "Probability of seamless communication" in wired-wireless networks. And the Method of Efficient QoS support that we supposed consists of "Multicast Routing-RSVP Protocol architecture based on Mobile IP" and "Protocols internetworking model ".

• Proceedings of the IEEK Conference
• /
• 2000.07b
• /
• pp.600-603
• /
• 2000

In this paper, we propose the design method of distributed control system using Controller Area Network (CAN). CAN is an advanced serial communication protocol for distributed real-time control systems. It is a contention-based multi-master network whose timeliness properties come from its collision resolution algorithm which gives a high schedulable utilization and guaranteed bus access latency. With proposed method using CAN, we apply to robot controller. The effectiveness of proposed method is demonstrated by the simulation and experiment.

• Journal of KIISE:Information Networking
• /
• v.35 no.4
• /
• pp.301-310
• /
• 2008

In the existing literature, the handover process reveals numerous problems manifested by high movement detection latency. FMIPv6 can reduce packet loss using a tunnel-based handover mechanism. However, this mechanism may cause performance degradation due to the out-of-sequence packets. Recently. Proxy Mobile IPv6 is proposed for network-based mobility management to reduce overhead in mobile node. PMIPv6 can decrease handover latency which related overhead in MN by using network agent. In this paper, we proposed optimized fast handover scheme called Fast Proxy Mobile IPv6 (EF-PMIPv6). The proposed EF-PMIPv6 can support fast handover using fast IAPP and ND schemes. Further, a mathematical analysis is provided to show the benefits of our scheme. In the analysis, various parameters are used to compare our scheme with the current procedures, while our approach focuses on the reduction of handover latency.

• Journal of KIISE:Information Networking
• /
• v.31 no.6
• /
• pp.620-632
• /
• 2004

IP is not suitable for mobile nodes by network-based routing because mobile nodes are dynamically change their network attachment point. Mobile-IP is an IETF standard providing continuous access to the Internet for mobile nodes, but it has the triangle routing problem. Also it has a performance degradation problem by massive packet loss during layer 3 handoff of mobile nodes. Especially, two IETF multicast support schemes for Mobile-IP do not guarantee the quality of realtime multimedia services because they have several problems such as long routing path, packet duplication(hi-directional tunneling) and massive packet loss(remote subscription). In this paper, we propose a lossless remote subscription scheme that guarantees the quality of realtime multimedia services over Mobile-IP. From the result of simulation, we verified that the proposed scheme in this paper can reduce the delay time of remote subscription by the effect of the low latency handoff scheme that is extended to apply to the multicast group management and it requires only 0.58% buffer spaces of the previously proposed lossless remote subscription scheme.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.2
• /
• pp.37-41
• /
• 2018

As individuals generate and share various content anytime and anywhere, new networking architectures, such as content-centric networking (CCN) using the content name as a packet identifier, have been in the spotlight recently. However, the current CCN hardly takes into account node mobility problems, especially the mobility of content sources. The movement of content sources causes long delivery latency and long service disruptions. To solve that, the tunneling-based redirection scheme was proposed. However, the tunneling-based scheme requires a location-update procedure whenever the network changes, which creates many control messages and causes long latency. So, this paper presents hierarchical mobility management of mobile CCN to reduce the number of control messages and handoff latency. Performance evaluation shows that the proposed scheme can provide low control overhead, which results in network scalability.