• The Journal of the Korea Contents Association
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• v.6 no.11
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• pp.295-301
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• 2006

The scope ID field of IPv6 multicast address indicates the zone of the destination for which a multicast traffic is intended. Without any further examination on the header field, the scope ID enables a router to determine whether the traffic will be forwarded to a subnet or not. For the graceful migration from IPv4 networks to IPv6 networks, various IPv6 applications working through IPv4 networks are indispensable during the migration period. This paper describes development of an interactive remote lecture system providing service integration on voice, image, and data of teaching materials. Access right to the network for dialog among multicast group members is controlled via additional TCP (Transmission Control Protocol) session. A jitter buffer algorithm was implemented to improve the voice communication jitters.

• Journal of the Korea Society of Computer and Information
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• v.10 no.4 s.36
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• pp.249-257
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• 2005

A Markov model for the IEEE 802.11 standard which is the most widely deployed wireless LAN protocol, is designed and the channel throughput is evaluated. The DCF of 802.11, which is based on CSMA/CA protocol, coordinates transmissions onto the shared communication channel. In this paper, under a finite load traffic condition and the assumption of packet loss after the final backoff stage. We present an algorithm to find the transmission probability and derive the formula for the channel throughput. The proposed model is validated through simulation and is compared with the case without packet losses.

• The KIPS Transactions:PartC
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• v.12C no.3 s.99
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• pp.387-394
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• 2005

Every MAC (Medium Access Control) sub-layers of IEEE 802.11x, including IEEE 802.11e, defines Connection-based and CF (Contention Free)-based service functions in common. In this paper, a New-CF method is proposed. In the proposed method, conventional Round Robin method, which is used as a polling method by IEEE 802.11x PCF (Point Coordination Function) or IEE 802.11e HCCA, is modified to give weights to channels with heavier traffic load and to provide those weighted channels with more services. Based on NS-2 simulations, it is verified the proposed method shows better throughput in general, particularly under unbalanced traffic load conditions.

• Journal of Korea Multimedia Society
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• v.10 no.4
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• pp.462-469
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• 2007

ATM protocol has the techniques such as cell discarding priority, traffic shaping and traffic policing. ATM based MPLS(Multiprotocol Label Switching) is discussed for its provisioning QoS commitment capabilities, traffic engineering and smooth migration for BcN using conventional ATM infra in Korea. This paper proposes preventive congestion control mechanism for detecting HTR(Hard To Reach) LSP(Label Switched Path) in ATM based MPLS systems. In particular, we decide HTR LSP using real time signaling information(etc., PTI,AIS/RDI) for applying HTR concept in circuit switching to ATM based MPLS systems and use those session gap and percentage based control algorithm that were used in conventional PSTN call controls. We concluded that it maximized the efficiency of network resources by restricting ineffective machine attempts. Proposed control can handle 208% call processing and more than 147% success call, than those without control. It can handle 187% BHCA(Busy Hour Call Attempts) with 100 times less than use of exchange memory.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.5
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• pp.555-564
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• 2016

This paper proposes a time slot allocation scheme for military patrol environments. This proposal comes from analysis of traffic properties in a military patrol environment. In the near future, robots are expected to explore enemy grounds and measure threat, taking the place of human patrol. In order to control such robots, control messages must be extremely accurate. One mistake from the control center could cause a tragedy. Thus, high reliability must be guaranteed. Another goal is to maintain a continual flow of multimedia data sent from patrol robots. That is, QoS (Quality of Service) must be guaranteed. In order to transmit data while fulfilling both attributes, the per-path based centralized TDMA slot allocation scheme is recommended. The control center allocates slots to robots allowing synchronization among robots. Slot allocation collisions can also be avoided. The proposed scheme was verified through the ns-3 simulator. The scheme showed a higher packet delivery ratio than the algorithm in comparison. It also performed with shorter delay time in the downlink traffic transmission scenario than the algorithm in comparison.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.1
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• pp.191-197
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• 2012

In this paper we propose the FQSM(Fairness and QoS Supporting MAC) protocol that supports fairness and Quality of Service(QoS). The received or measured data traffics will be assigned a priority level according to its transmission urgency in the FQSM. And the load prediction algorithm is used to support the fairness between different priority traffics. For this, the buffer length values of the nodes are continuously monitored for a some period. Based on the buffer length variations for this period, the order of transmission is determined. FQSM also adapts cross-layer concept to rearrange the data transmission order in each sensor node's buffer, saves energy consumption by allowing few nodes in data transmission, and prolongs the network lifetime.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.5
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• pp.133-142
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• 2004

Recently, the growth of Internet and a variety of multimedia services through Internet increasingly demands high-speed packet transmission, the new routing function, and QoS guarantee on conventional routers. Thus, a new switching mechanical called the MPLS(Multi-Protocol Label Switching), was proposed by IETF(Internet Engineering Task Force) as a solution to meet these demands. In addition the deployment of MPLS network supporting Differentiated Services is required. In this paper, we propose the architecture of the MPLS switch supporting Differentiated Services in the MPLS-based network. The traffic conditioner consists of a classifier, a meter, and a marker. The VOQ-PHB module, which combines input Queue with each PHB queue, is implemented to utilize the resources efficiently. It employs the Priority-iSLIP scheduling algorithm to support high-speed switching. We have designed and verified the new and fast hardware architecture of VOQ-PHB and the traffic conditioner for QoS and high-speed switching using NS-2 simulator. In addition, the proposed architecture is modeled in VHDL, synthesized and verified by the VSS analyzer from SYNOPSYS. Finally, to justify the validity of the hardware architecture, the proposed architecture is placed and routed using Apollo tool.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12A
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• pp.964-974
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• 2003

With increasing use of a personal mobile computer. the Mobile IPv6 is one of the main protocols that support mobility and complies with IPv6 specification. Similar to the mobile IPv6, the mobile IPv6 also has limitations on fast moving condition. The Hierarchical Mobile IPv6 is a solution that overcomes these limitations. The Hierarchical Mobile IPv6 is a micro mobility protocol that supports fast mobile IP handover and reduces signaling overhead with Mobility Anchor Point(MAP). But until now no paging method is applied to the Hierarchical Mobile IPv6 to reduce unnecessary signaling overhead and power consumption of mobile nodes. So, the paging mechanism for the Hierarchical Mobile IPv6 is proposed in this paper. the mechanism is implemented by making use of the destination option header and extension function and the last location algorithm. The results show that the Hierarchical Mobile IPv6 with the paging ability reduces the traffic of mobile networks by removing unnecessary binding update packet generated whenever handover takes place. Also, the larger the paging size is. the less the number of BU(Binding Update) massage generated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4C
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• pp.343-355
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• 2003

Fair bandwidth allocations at routers protect adaptive flows from non-adaptive ones and may simplify end-to end congestion control. However, traditional fair bandwidth allocation mechanisms, like Weighted Fair Queueing and Flow Random Early Drop, maintain state, manage buffera and perform packet scheduling on a per-flow basis. These mechanisms are more complex and less scalable than simple FIFO queueing when they are used in the interi or of a high-speed network. Recently, to overcome the implementation complexity problem and address the scalability and robustness, several fair bandwidth allocation mechanisms without per-flow state in the interior routers are proposed. Core-Stateless Fair Queueing and Rainbow Fair Queuing are approximates fair queueing in the core-stateless networks. In this paper, we proposed simple Layered Fair Queueing (SLFQ), another core-stateless mechanism to approximate fair bandwidth allocation without per-flow state. SLFQ use simple layered scheme for packet labeling and has simpler packet dropping algorithm than other core-stateless fair bandwidth allocation mechanisms. We presente simulations and evaluated the performance of SLFQ in comparison to other schemes. We also discussed other are as to which SLFQ is applicable.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.9
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• pp.35-46
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• 2011

Future Internet should support more efficient mobility management, flexible traffic engineering and various emerging new services. So, lots of traffic engineering techniques have been suggested and developed, but it's impossible to apply them on the current running commercial Internet. To overcome this problem, OpenFlow protocol was proposed as a technique to control network equipments using network controller with various networking applications. It is a software defined network, so researchers can verify their own traffic engineering techniques by applying them on the controller. In addition, for high-speed packet processing in the OpenFlow network, programmable NetFPGA card with four 1G-interfaces and commercial Procurve OpenFlow switches can be used. In this paper, we implement an OpenFlow test-bed using hardware-accelerated NetFPGA cards and Procurve switches on the KREONET, and implement CSPF (Constraint-based Shortest Path First) algorithm, which is one of popular QoS routing algorithms, and apply it on the large-scale testbed to verify performance and efficiency of multimedia traffic engineering scheme in Future Internet.