• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1162-1169
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• 2012

One of the important operational requirements for mission critical Ethernet networked system is having the fault tolerant capability. Such capability can be obtained by equipping multiport Network Interface Card (NIC) in each node in the system. Conventional NIC uses two or more Media Access Controls (MACs) and a co-processor for the MAC switching whenever an active port fails. Since firmware is needed for the co-processor, longer fail-over switching and degraded throughput can be generally expected. Furthermore the system upgrading requiring the firmware revision in each tactical node demands high cost. In this paper we propose a novel single MAC based NIC that does not use a co-processor, but just use general discrete building blocks such as MAC chip and switching chip, which results in better performances than conventional method. Experimental results validate our scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.529-540
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• 2015

The NGN should support an ubiquitous environment in which users can use multiple devices. Especially, services should be provided to users in a seamless manner across multiple devices which are dynamically found in users' vicinity. Therefore, supporting service continuity is essential in the NGN. Currently the IMS, which is a session control layer for the NGN, deals with session control procedures in detail for service continuity. However, the IMS provides limited methods how users can find target terminals for transferring the session. The target terminals tend to be located near in user's physical location, and could be shared among different users. For providing better service experience in the NGN, The NGN needs to encompass methods to enable for users to use the dynamically-found terminals in users' vicinity seamlessly. In this paper, we introduce a novel registration method based on virtual ISIM by which the target terminals in user's vicinity can register themselves to the IMS, and also we discuss how service continuity is supported.

• Journal of Software Engineering Society
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• v.25 no.2
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• pp.35-47
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• 2012

Variable Message Format(VMF) is a communications protocol that allows computers to exchange tactical military information over low-data-rate bearers. VMF is designed to define message length and structure variably in order to allow the user to transmit only the relevant information by using indicators. However, flexibility of messages makes it difficult to analyze messages structure and figure out meanings. Furthermore, whenever messages are added or modified, message processing software should be updated and distributed to systems. In this paper, we propose a systematic approach to defining VMF messages that uses the international standard notation ASN.1. By describing VMF messages in ASN.1, protocol architects can deal with VMF messages accurately and conveniently, and use various ASN.1 tool. This paper develops ASN.1 description templates for VMF message segments, and presents an approach to describing VMF messages in ASN.1 by combining the templates.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.7
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• pp.851-856
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• 2013

Recently, as the tactical environment has changedto one of network-centric warfare, where all components are connected through a network, much emphasis has been placed on the use of an artificial satellite for achieving high communication speeds. To provide a high-quality artificial satellite link, stabilization is very important in a platform. Previous stabilization control techniques used PI control, which is commonly used for vessels. However, for ground terminals that require a higher communication speed, the antenna should move faster to track an artificial satellite within a short period of time. Moreover, the terminals must be equipped with proper sensors and algorithms so that they can detect and compensate for external disturbances while tracking the artificial satellite. In this study, through the analysis of the dynamic model of an antenna system, a stabilization algorithm for ground terminals was proposed;this algorithm shows high isolation performance in the low-frequency range and includes $PI^2$ control.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.12
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• pp.2261-2269
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• 2017

The current LTE network system provides service by locally allocating eNodeB to the EPC(Evolved Packet Core). However, it is not suitable for inter-node communication based on the distributed network environment. In this paper, we propose an integrated system by configuring E-UTRAN and EPC as All-In-One type to enable service in each distributed node. M2M UE is mounted on a each node for wireless In-band backhaul link. The integrated node provides inter-node communication over the wireless in-band backhaul link. If a normal UE moves and an access node changes in the system all entities of LTE integrated into one, it is necessary to change the P-GW which is IP anchor. In order to support the inter-node mobility even if P-GW is changed, We defined UPFE(User Packet Forwarding Extension) scheme and implemented the handover procedure of EPC. Also, we analyze the cell range of the integrated LTE system with the addition of the node and compare the handover delay with the current system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.1
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• pp.110-121
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• 2016

Link-16 is a representative TDL operated by US air force and NATO and supports structure of Multi-net. Under Multi-net, military operation can be conducted effectively since terminal nodes in Link-16 hop over total frequency band simultaneously. As air traffic is rapidly increasing, new aeronautical system is introduced or existing system should be expanded to accommodate increasing air traffic and frequency band assigned for operating this system is scarce. It is scheduled to implement frequency remapping to solve frequency scarcity. With limited frequency band for operating Link-16, as frequency remapping is implemented, degradation of Multi-net performance can happen since multiple access interference in Link-16 is increasing so it is difficult to conduct multiple military operations. Thus, Group-based frequency hopping scheme is proposed to solve this problem. We verified the performance of the proposed scheme is improved.

• Spatial Information Research
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• v.22 no.1
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• pp.19-26
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• 2014

Recently, ICT environments have been increasingly developed and the pattern of the war also has been changed to NCW. The development of communication and network technology, for example, C4I and TDL(Tactical Data Link), has been prosperous and rapid. But the geospatial intelligence field which is the basis of the network frames relatively has not been developed. The purpose of this paper is to foster the geospatial governance in terms of the defense perspective. In order to do that, this paper deals with the U.S. Intelligence Community(IC) and the U.S. Army Global Information Grid(GIG), LandWarNet and those could be good examples of roles and statuses of geospatial intelligence. IC has been produced essential intelligence which is required for policymakers and military leaders. IC has several stove-piped intelligence process systems which have been separately developed and competed. And so as to complete GIG, the U.S. Army adopted LandWarNet. The U.S. Corps of Engineers organized the Army Geospatial Center(AGC) on 1 October 2009 to support LandWarNet. In order to develop NCW, we should recognize geospatial intelligence as the basis of network framework and make a central leading organization of defense geospatial intelligence. The mission of Korea Defense Geospatial-Intelligence Agency should be changed from producing GEOINT to a strategic GEOINT agency. The Army should organize a laboratory of geospatial intelligence field. The mission of producing GEOINT should be transferred to a geospatial intelligence battalion which is newly organized.