• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.6
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• pp.520-527
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• 2015

The key exchange protocols are very crucial tools to provide the secure communication in the broadband satellite access network. They should be required to satisfy various requirements such as security, key confirmation, and key freshness. In this paper, we present the security functions in ETSI(European Telecommunications Standards Institute), and analyze the specification of the security primitives and the key exchange protocols for the authenticated key agreement between RCST(Return Channel Satellite Terminal) and NCC(Network Control Centre). ETSI key exchange protocols consists of Main Key Exchange, Quick Key Exchange, and Explicit Key Exchange. We analyse the pros and cons of key exchange protocols based on performance analysis and performance evaluation.

• Journal of IKEEE
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• v.2 no.1 s.2
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• pp.122-133
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• 1998

The CL network fer CBDS(Connectionless Broadband Data Service) defined by ITU-(International Telecommunication Union-Telecommunication) consists of CL(ConnectionLess) servers which route frames and links which connect between CL user and CL server or between CL servers[1][2]. In this configuration, two kinds of congestion, CL link congestion and CL server congestion may occur. Therefore this paper has proposed the scheme that can deal with the above congestion state of LAN traffic efficiently in interworking LANs in ATM network. Proposed schemes ale link-by-link scheme and hybrid scheme. Link-by-link scheme uses the ABR feedback loops of AIM layer between CL user and CL server or between CL servers, and the header translation table carrying out the routing function of frame. And hybrid scheme is the scheme that adds end-to-end loop to link-by-link scheme and then uses RM message using CLNAP-PDU(ConnectionLess Network Access Protocol - Protocol Data Units) of CL layer. These schemes can be implemented easily because of using the ABR loop of ATM layer, end-to-end loop of CL layer, and the routing function of CL server. In this paper the characteristic and effects of two schemes in CL server bas been compared and analyzed.

• The Transactions of the Korea Information Processing Society
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• v.4 no.2
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• pp.531-542
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• 1997

In this paper,we propose applicable methodology using simple scenarios for the architecture and its procedure of sibnalling at the NNI for B-ISDN in Korea.By the recent technologies,the flexible and intergrated networks of the future are designed, and the infrastructure hardware and software of those networks are sdsigned based on the modular concepts.Also the ATM-based B-ISDN must be able to support the broadband transmission function for providing various services with diverse bandwidths such as multimedia serivce and the function for controlling services and bandwidth is necessaty.Currently,the trquirements at the NNI for B-ISDN in korea atr based on the network mode connection type which is connection setup strucuture.They must show the upper/lower layer conformance to have the flexibility in new services and guarantee the interoperability between the network functions.But,network functions and protocol specifications described in this paper are limity to the first stage target system in korea.Therefore,we present the modular architecture which is corresponding to the B-ISUP of HAN/B-ISDN with those characteristics.Currently applicable architecture and procedure for B-ISUP and the functions of expandable modular architecture are also proposed.

• ETRI Journal
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• v.26 no.4
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• pp.321-331
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• 2004

In this paper, we propose a new dynamic bandwidth allocation (DBA) algorithm for multimedia services over Ethernet PONs (passive optical networks). The proposed algorithm is composed of a low-level scheduler in the optical network unit (ONU) and a high-level scheduler in the optical line terminal (OLT). The hierarchical DBA algorithm can provide expansibility and efficient resource allocation in an Ethernet PON system in which the packet scheduler is separated from the queues. In the proposed DBA algorithm, the OLT allocates bandwidth to the ONUs in proportion to the weight associated with their class and queue length, while the ONU preferentially allocates its bandwidth to queues with a static priority order. The proposed algorithm provides an efficient resource utilization by reducing the unused remaining bandwidth caused by the variable length of the packets. We also define the service classes and present control message formats conforming to the multi-point control protocol (MPCP) over an Ethernet PON. In order to evaluate the performance, we designed an Ethernet PON system on the basis of IEEE 802.3ah "Ethernet in the first mile" (EFM) using OPNET and carried out simulations. The results are analyzed in terms of the channel utilization, queuing delay, and ratio of the unused remaining bandwidth.

• Journal of Korea Multimedia Society
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• v.2 no.2
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• pp.176-183
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• 1999

Using Asynchronous Transfer Mode(ATM) which is a high-bandwidth, low-delay, cell switching and multiplexing technology, Broadband-Integrated Services Digital Network (B-ISDN) can support communication services of all kinds. To evaluate the performance of ATM networks, traffic source models to meet the requirements are demanded. We can obtain random traffic distribution for ATM networks by using the Cellular Automata (CA) which have effective random pattern generation capability. In this paper we propose an algorithm using 2-D LHCA to generate more effective random patterns with good random characteristics. And we show that the randomness by 2-D LHCA is better than that of the randomness by 1-D LHCA.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.14-26
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• 2008

IP over Ethernet technology widely used as Internet access uses the ARP(Address Resolution Protocol) that translates an ip address to the corresponding MAC address. recently, there are ARP security attacks that intentionally modify the IP address and its corresponding MAC address, utilizing various tools like "snoopspy". Since ARP attacks can redirect packets to different MAC address other than destination, attackers can eavesdrop packets, change their contents, or hijack the connection. Because the ARP attack is performed at data link layer, it can not be protected by security mechanisms such as Secure Shell(SSH) or Secure Sockets Layer(SSL). Thus, in this paper, we classify the ARP attack into downstream ARP spoofing attack and upstream ARP redirection attack, and propose a new security mechanism using DHCP information for acquisition of IP address. We propose a "DHCP snoop mechanism" or "DHCP sniffing/inspection mechanism" for ARP spoofing attack, and a "static binding mechanism" for ARP redirection attack. The proposed security mechanisms for ARP attacks can be widely used to reinforce the security of the next generation internet access networks including BcN.

• ETRI Journal
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• v.27 no.1
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• pp.89-94
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• 2005

This paper describes a low-loss, compact, 40-channel arrayed waveguide grating (AWG) which utilizes a monolithically integrated spot-size converter (SSC) for lowering the coupling loss between silica waveguides and standard single-mode fibers. The SSC is a simple waveguide structure that is tapered in both the vertical and horizontal directions. The vertically tapered structure was realized using a shadow-mask etching technique. By employing this technique, the fabricated, 40-channel, 100 GHz-spaced AWG with silica waveguides of 1.5% relative index-contrast showed an insertion-loss figure of 2.8 dB without degrading other optical performance.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.478-483
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• 2003

In this paper, in order to fabricate the circularly polarized diversity system which will mitigate multipath fading, 5.8GHz band microstrip array antenna were designed and fabricated. These antenna were designed using Ensemble 6.0 program and the fabricated antenna were vertical and horizontal polarized antenna, left-handed circularly polarized antenna, and right-handed circularly polarized antenna. The designed antenna parameters included S11 and impedance characteristics of fabricated antenna were measured using Network Analyzer(8753ES). From the measurement results, the S11 for each polarization antenna at resonance frequency of 5.8GHz band was showed -38dB, -44dB, and -50dB respectively and it was similar to the simulation result, and also the impedance can be matched at $50{\Omega}$. In order to compare polarization characteristics, broadband measurement was also conducted in this paper.

• Journal of Communications and Networks
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• v.9 no.4
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• pp.446-456
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• 2007

Increased access to broadband networks has led to a fast-growing demand for voice and video over IP(VVoIP) applications such as Internet telephony(VoIP), videoconferencing, and IP television(IPTV). For pro-active troubleshooting of VVoIP performance bottlenecks that manifest to end-users as performance impairments such as video frame freezing and voice dropouts, network operators cannot rely on actual end-users to report their subjective quality of experience(QoE). Hence, automated and objective techniques that provide real-time or online VVoIP QoE estimates are vital. Objective techniques developed to-date estimate VVoIP QoE by performing frame-to-frame peak-signal-to-noise ratio(PSNR) comparisons of the original video sequence and the reconstructed video sequence obtained from the sender-side and receiver-side, respectively. Since processing such video sequences is time consuming and computationally intensive, existing objective techniques cannot provide online VVoIP QoE. In this paper, we present a novel framework that can provide online estimates of VVoIP QoE on network paths without end-user involvement and without requiring any video sequences. The framework features the "GAP-model", which is an offline model of QoE expressed as a function of measurable network factors such as bandwidth, delay, jitter, and loss. Using the GAP-model, our online framework can produce VVoIP QoE estimates in terms of "Good", "Acceptable", or "Poor"(GAP) grades of perceptual quality solely from the online measured network conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3B
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• pp.288-303
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• 2009

In the near future it is foreseen that a genuine multimedia service over the WiMAX system is provided in a worldwide manner by exploiting the QoS technologies introduced in the wireless and wired broadband network. In this work we propose a pricing scheme for the multimedia service over the generic WiMAX system that supports a full QoS functionality. We assume real-time services such as the voice and video as well as the nonreal-time service such as the conventional high-speed data, and we propose a pricing and charging scheme for those services by investigating the inherent characteristics of those services and the multiple-class of QoS-service provided to them. After that we propose a method to compute expected revenue that is obtained from the WiMAX system by using an analytic method to estimate the usage of the bandwidth resources for the different class of services. Via numerical experiment, we verify the implication of the work.