• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.713-716
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• 1998

We propose the dejittering method against the jitter originated from the cell losses in ATM network when CBR traffic is transfereed on AAL5. Cell numbering algong with maintaining a timer at receier side introduces 0.669 times peak-to-peak PDV of the AAL5 PDU to that in ITU-T AAL5 standard, and the AAL5 user-HDTV decoder-receives the same or more error-free transport packets in the proposed algorithm than those in the ITU-T AAL5 standard for the same network simulation environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3B
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• pp.85-94
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• 2005

In this paper, we propose a reliable high-speed UDP-based media transport with an adaptive error control. The proposed adaptive transport scheme controls the amount of redundancy by monitoring the network in order to adapt to network fluctuations efficiently. The feedback of receiver enables the sender to be aware of current reception status (i.e., rate and type of packet loss) and to estimate the expected network status. Based on this, the proposed transport attempts to enable reliable transport by adaptively controlling the amount of both whole sending rate and the ratio for adaptive FEC code. Experiment with high-speed network has been conducted to verify the performance of the proposed system that demonstrates the enhanced reliability of the proposed transport at the speed of up to several hundred Mbps.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.4
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• pp.216-223
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• 2013

As the fast growth of using Internet, the requests of clients having different types and pressing loads on the server have been increased in World Wide Web. Thus the interesting issue is how to measure the real capacity of a Web Server. There have been much recent studies about measuring the capacity of web server. But the cause of Server response time delay is not just server itself but also network packet loss. To measure the practical capacity of web server, we generate scalable clients using Posix Thread, transport packets which were generated by scalable clients to the server using UDP and receive the packets which were the remain packet from network packet loss using TCP. In this paper, we propose a method to measure the practical capacity of a web server using the Scalable Clients based on Posix Thread and the transport on Application level.

• ETRI Journal
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• v.30 no.2
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• pp.216-226
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• 2008

This paper proposes a novel transport network architecture for the next generation network (NGN) based on the optical burst switching technology. The proposed architecture aims to provide efficient delivery of various types of network traffic by satisfying their quality-of-service constraints. To this end, we have developed a soft-state bandwidth reservation mechanism, which enables NGN transport nodes to dynamically reserve bandwidth needed for active data burst flows. The performance of the proposed mechanism is evaluated by means of numerical analysis and NS2 simulation. Our results show that the packet delay is kept within the constraint for each traffic flow and the burst loss rate is remarkably improved.

• ETRI Journal
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• v.32 no.2
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• pp.241-247
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• 2010

We propose and experimentally demonstrate a service-aware optical transport system. The proposed service-aware optical transport system makes a flow based on service type and priority of traffic. The generated flow is mapped to a corresponding sub-${\lambda}$ for transport over an optical network. Using sub-${\lambda}$ provided by the centralized control plane, we could effectively provide quality-of-service guaranteed Ethernet service and best-effort service simultaneously in a single link. The committed information rate (CIR) traffic and best-effort traffic are assigned to different sub-${\lambda}s$. The bandwidth of the CIR traffic is guaranteed without being affected by violation traffic because the bandwidth is managed per each sub-${\lambda}$. The failure detection time and restoration time from a link failure is measured to be about 60 ${\mu}s$ and 22 ms, respectively, in the ring network. The measured restoration time is much smaller than the 50 ms industry requirement for real-time services. The fast restoration time allows the proposed service-aware optical transport system to offer high availability and reliability which is a requirement for transport networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.11
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• pp.975-983
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• 2012

Multi network interface has become common phenomenon for mobile devices such as smart phone which has 3G, LTE-advanced, WiFi. Consequently, there are researches for a transmission strategies using multiple paths below on end-to-end connection. MPTCP which is proposed and being standardized by the IETF as a new transport protocol can perform concurrent multipath transfer using multiple network interfaces. However, current MPTCP has performance degradation when it use heterogeneous networks which have quite different network characteristics. Therefore, this paper proposes the packet scheduling scheme and receiver-based recovery scheme to reduce the performance degradation due to reordering problem. Also, simulation results show that the proposed scheme can improve throughput and retransmission performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.648-652
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• 2003

In the GPRS(General Packet Radio Service) network, the transport layer between SGSN(Serving GPRS Support Node) and GGSN (Gateway GPRS Support Node) is based on IP-Over ATM Network. which means that the connectionless IP traffic is transmitted through connection oriented ATM transport layer. Efficient resource management is needed to perform connection and disconnection of the pertinent VC because of the connectionless IP traffic being passed through ATM transport layer In this paper, Internet Web service traffic model in the GPRS network is applied to the various VC holding Cost Pricing Model. each method is compared through analyzing each VC utilization and setup rate.

• Journal of Broadcast Engineering
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• v.23 no.5
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• pp.682-692
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• 2018

In this paper, we propose an ARQ packet error control scheme using multiple threads in delivering massive capacity of multimedia based on MMT(MPEG Media Transport) protocol. On the sending side, each frame that constitutes an image is packetized into MMT packets based on MMT protocol. The header of the packet stores the sequence number of the frames contained in the packet and the time of presentation information. The payload of the packet stores the direct information that comprises the frame. The generated MMT packet is transmitted to the IP network. The receiving side checks if any error has occurred in the received packet. For any identified error, it controls the error through ARQ error control scheme and reconfigure the frame according to the information stored in the header of the received packet. At this point, a multi-threading based transport design is constructed so that each thread takes over a single frame, which increases the transmission efficiency of massive capacity multimedia. The efficiency of the multi-threading transport method is verified by solving the problems that might arise when using a single-thread approach if packets with errors are retransmitted.

• ETRI Journal
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• v.38 no.1
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• pp.18-29
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• 2016

In this paper, we discuss the issues of providing protection for point-to-multipoint connections in both Ethernet and MPLS-TP-based packet transport networks. We introduce two types of per-leaf protection-linear and ring. Neither of the two types requires that modifications to existing standards be made. Their performances can be improved by a collective signal fail mechanism proposed in this paper. In addition, two schemes - tree protection and hybrid protection - are newly proposed to reduce the service recovery time when a single failure leads to multiple signal fail events, which in turn places a significant amount of processing burden upon a root node. The behavior of the tree protection protocol is designed with minimal modifications to existing standards. The hybrid protection scheme is devised to maximize the benefits of per-leaf protection and tree protection. To observe how well each scheme achieves an efficient traffic recovery, we evaluate their performances using a test bed as well as computer simulation based on the formulae found in this paper.

• Journal of Communications and Networks
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• v.4 no.2
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• pp.108-117
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• 2002

TCP, which was developed on the basis of wired links, supposes that packet losses are caused by network congestion. In a wireless network, however, packet losses due to data corruption occur frequently. Since TCP does not distinguish loss types, it applies its congestion control mechanism to non-congestion losses as well as congestion losses. As a result, the throughput of TCP is degraded. To solve this problem of TCP over wireless links, previous researches, such as split-connection and end-to-end schemes, tried to distinguish the loss types and applied the congestion control to only congestion losses; yet they do nothing for non-congestion losses. We propose a novel transport protocol for wireless networks. The protocol called VS-TCP (Variable Segment size Transmission Control Protocol) has a reaction mechanism for a non-congestion loss. VS-TCP varies a segment size according to a non-congestion loss rate, and therefore enhances the performance. If packet losses due to data corruption occur frequently, VS-TCP decreases a segment size in order to reduce both the retransmission overhead and packet corruption probability. If packets are rarely lost, it increases the size so as to lower the header overhead. Via simulations, we compared VS-TCP and other schemes. Our results show that the segment-size variation mechanism of VS-TCP achieves a substantial performance enhancement.