• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.706-715
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• 2001

TCP typically offers reasonable end-to-end performance to users regardless of the bandwidth and error characteristics of particular network technology, The robustness of TCP has contributed to its success in the internet environment. The role of communications is already well established in the office environment. With the advent of cheap, affordable broadband communications and the increasing complexity of consumer goods, it seems natural to extend the network into homes. In-home networking means a high-speed communication among the digital appliances within a home. Introduction of application over high-speed home network using TCP/IP protocol is increasing. The integrated environment of internet and home network is demanding as well. We have validated TCP model over high speed home network environment, investigated the throughput behavior of TCP over IEEE 1399 home networks, and evaluated a potential solution for high performance of TCP over IEEE 139t home networks. The simulation model has produced several interesting results in the performance of TCP over IEEE 1394 home network.

• Journal of KIISE:Information Networking
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• v.36 no.4
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• pp.360-368
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• 2009

Recently, broadband access networks have been competitively deployed all over the world with the development of various multimedia services for such a network. ETRI(Electronics and Telecommunications Research Institute) built the FTTH(Fiber-To-the-Home) service center to develop a next-generation equipment and a high-quality service/platform as well as to promote domestic industry in the field of optical communication. The FTTH service center has a variety of test equipments such as FTTH standard testbed for a BMT(bench mark test), a network operation center, and IPTV service equipments. Also, ETRI deployed a new type of commercial optical access networks cooperating with ISP(Internet Service Provider). This paper presents the performance evaluation of FTTH E-PON(Ethernet Passive Optical Network) system as a platform for TPS(Triple Play Service) based on QoS(Quality of Service) and QoE(Quality of Expericence) issues. This FTTH E-PON system is successfully demonstrated as an optical access network system by commercial network service provider and the FTTH service center of ETRI.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.7
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• pp.680-695
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• 1991

In this paper, the conditions on the number of required copies of a self-routing network with and without extra stages in back-to-back manner are presented respectively for a nonblocking $Multi-Log_2N$ multiconnection network. Actually the obained results hold regardless of connection patterns, i.e., whether a network deploys on-to-one connections or multiconnections. Thus open problems on the nonblocking condition for a multi $Multi-Log_2N$ multiconnection network are solved. Interestingly some of the given formulas comprise the Benes network and the Canto network as a special case repectively. A novel switching system architecture deploying a distributed calls-distribution algorithm is provided to design a nonblocking $Multi-Log_2N$ photonic switching network using a directional coupler. And a directional couplex based call holding demultiplexer is introduced to hold a call until blocking disappears in a switching network and let it enter to a network, provided that the number of switching networks is less than that of required switching networks for a nonblocking $Multi-Log_2N$ network.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.7
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• pp.930-939
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• 2021

In recent years, the use of broadband bandwidth and redundant links for stable transmission in networks has resulted in excessive energy consumption and reduced transmission efficiency. In this paper, we propose an optimization algorithm that reduces the number of transmission links and minimizes transmission energy by removing redundant traffic in networks where traffic redundancy is allowed. The optimization algorithm proposed in this paper uses the meta-heuristic method using Tabu search algorithm. The proposed optimization algorithm minimizes transmission energy by designing a neighborhood generation method that efficiently routes overlapping traffic. The performance evaluation of the proposed optimization algorithm was performed in terms of the number of links used to transmit all traffic generated in the network and the transmission energy consumed. From the performance evaluation results, it was confirmed that the proposed algorithm is superior to other algorithms previously proposed.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.4
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• pp.87-93
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• 2009

Wireless mesh networks (WMNs) are emerging technologies that provide ubiquitous environments and wireless broadband access. The aggregate capacity of WMNs can be improved by minimizing the effect of channel interference. The IEEE 802.11b/g standard which is mainly used for the network interface technology in WMNs provides 3 multiple channels. We must consider the channel scanning delay and the channel dependency problem to effectively assign channels in like these multi-channel WMNs. This paper proposes a cluster-based channel assignment (CB-CA) algorithm for multi-channel WMNs to solve such problems. The CB-CA does not perform the channel scanning and the channel switching through assigning co-channel to the inter-cluster head (CH) links. In the CB-CA, the communication between the CH and cluster member (CM) nodes uses a channel has no effect on channels being used by the inter-CH links. Therefore, the CB-CA can minimize the interference within multi-channel environments. Our simulation results show that CB-CA can improve the performance of WMNs.

• 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.

• ETRI Journal
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• v.36 no.5
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• pp.791-798
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• 2014

As a new hybrid broadcasting service, augmented broadcasting shows enhanced broadcasting content on a large TV screen, while augmented reality (AR) on a mobile device augments additional graphical content onto an input image from the device's own camera to provide useful and convenient information for users. A one-sided broadcasting service using AR has already been attempted in virtual advertisements during sport broadcasts. However, because its augmentation is preprocessed before the video image is transmitted, the viewer at home may have no influence on this formation; and no interaction for the user is possible unless the viewer has a direct connection to the content provider. Augmented broadcasting technology enables viewers to watch mixed broadcasting content only when they want such service and to watch original broadcasting content when they do not. To realize an augmented broadcasting service, the most important issue is to resolve the hybrid content synchronization over heterogeneous broadcast and broadband networks. This paper proposes a novel hybrid content synchronization scheme for an augmented broadcasting service and presents its implementation and results in a terrestrial DTV environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.1945-1956
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• 1994

In this paper, a multiaccess network protocol for high-speed communication is proposed, which enables multimedia sevices with integrating the existing networks. We examine the traffic control mechanisms and configurations for the network architecture and compare with various protocols which are suitable to high speed LAN/MAN and propose an adaptive access control mechanism. ATMR has low channel utilization due to window size reset time, and that MetaRing is very sensitive over the change of traffic load. This suggested protocol, however, has quite a good performance for that situation by adding adaptive parameter condition. This mechanism may introduce a model of small-scaled Broadband Integrated Service Network and be used as an internetworking system for the ATM network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.11
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• pp.2215-2227
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• 1994

A multicast switch, which can provide a single uniform switching function for vastly different classes of traffic, is crucial for the successful deployment of intergrated broadband networks. In this paper, we study the call blocking probability of heterogeneous circuit emulated traffic in a multicast switch. A previous work on the analysis of homogeneous traffic, where all calls have the same fan-out, show the performance showed that the call blocking probability increases rapidly as fan out increases. We study the performance of heterogeneous traffic, which consists of calls of different fan out, and show the performance gaps between larger fan-out traffic and smaller fan-out traffic are larger than those of homogeneous traffic these results indicate the necessity of efficient resource allocation policies to improve the performance of multicast calls. We conclude the paper introducing several methods to improve the performance of multicast traffic.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.12
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• pp.553-558
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• 2002

In this paper, an integrated balun using bondwire transformer is fabricated and measured. The bondwire transformer has 1ow conductor and substrate loss and kas high resonance frequency. So it is available to implement low loss broadband balun. From the measured results, 0.7 dB amplitude imbalance and about 2.5 $^{\circ}$ phase imbalance was achieved from 8.15 to 16.18 GHz. It is expected that the proposed balun can improve the performance of mixers, amplifiers and matching networks of antennas. It can also be integrated with other components due to its easier fabrication and smaller size than spiral transformer balun.