• Journal of KIISE:Information Networking
• /
• v.28 no.3
• /
• pp.435-446
• /
• 2001

In this paper, a new fairness control method is proposed to distribute DQDB-SR (Distributed-Queue Dual-Bus with Slot Reuse) network bandwidth fairly to all stations on client-server environments. By using an access limit that follows a characteristic of client-sever load patterns and a bandwidth borrowing and returning mechanism, the proposed mechanism imparts fairness bandwidth control capability to DQDB-SR. To implement the proposed mechanism, we find the optimal placement of erasure nodes that maximizes network capacity for DQDB-SR, and calculate the access limit. At overload conditions, simulation results show that the proposed mechanism does not deteriorate network throughput, and outperforms other fairness control mechanisms in a success rate and an average packet transfer delay.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.8
• /
• pp.1683-1690
• /
• 2005

This study examines dynamic flow control method in UDP, analyzes packet loss which is frequently used element in measuring existing dynamic flow control and characteristics of round trip time, and proposes a new method of measurement, RSST. The algorithm that uses the proposed RSST enables accurate measurement of network status by considering both the currently measured network status and the past history of network status in controlling the transmission rate. For comparison study, a network status measurement software program that displays detailed information about volume of transmission generation of network status, and flow pattern of network was developed. The performance test shows that the proposed algorithm can better adjust to network condition in terms of low pack loss rate over existing algorithms.

• The KIPS Transactions:PartC
• /
• v.9C no.1
• /
• pp.45-54
• /
• 2002

MPLS(Multiprotocol Label Switching) is regarded as a core technology for migrating to the next generation Internet. In this paper, we propose an dynamic flow admission control supporting DiffServ(Differentiated Services) to provide QoS in MPLS networks. Our proposed model dynamically adjusts the amount of admissible traffic based on transmittable capacity over one outgoing port. It then transmits the Packets while avoiding congested area resulting traffic loss. Ingress LSRs find out the congested area by collecting network state information at QoS state update for QoS routing table. Our Proposed model manages the resource efficiently by protecting the waste of resources that is a critical Problem of DiffServ and makes much more flows enter the network to be served.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.6
• /
• pp.1327-1332
• /
• 2015

In this paper, we studied several aspects that affect the quality of VoIP using WiFi network. It's clear that the background data traffic within an AP, the end-to-end delay and the traffic loss of TCP/IP network gives serious effects on the voice quality. A kind of access control for the VoIP connection within an AP should be done for the acceptable voice quality.

• Annual Conference of KIPS
• /
• 2003.05b
• /
• pp.1129-1132
• /
• 2003

사용자의 인터넷 서비스 고속화 요구가 증대되면서 스위치나 라우터 보안 장비와 같은 인터네트워킹 장비들의 성능 향상 요구도 커지고 있는데 이는 패킷을 처리하는 양과 속도를 향상시켜야 하다는 것을 의미한다. 스위치와 같은 라인 인터페이스 장치들은 주로 전용 하드웨어로 설계되므로 네트워크의 트래픽 처리 성능을 보장받을 수 있으나, 보안 장비나 네트워크 응용 장비들은 일반 서버 기반에서 트래픽을 처리하는 경우가 많아 시스템적으로 성능 향상에 제약을 받거나 성능 향상을 위해서 높은 비용을 지불해야 한다. 근래의 이러한 통신 관련 장비들에서의 패킷 처리 방식은 단순한 연결 차원을 넘어 패킷을 분석하고 연결을 제어하는 모습을 보이고 있는데 이러한 추가 작업 때문에라도 시스템에 많은 부하가 발생한다. 이러한 트래픽의 분석 처리를 빠르게 하기 위해서는 입력된 데이터와 설정된 규칙간의 비교와 판단이 빨라질 필요가 있는데, 본 논문에서는 이를 위해 기존에 연구된 몇 가지 S/W 적인 해결 방법과 H/W 적인 방법들을 분석하고, 더 나은 검색 성능을 위해 H/W 기반 네트워크 보조 프로세서를 이용한 방식을 제안하고 실험을 통하여 검증하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.10a
• /
• pp.117-120
• /
• 2001

In this paper, a contention-based reservation MAC protocol is proposed for non-real-time bursty traffic services in the wireless ATM networks. In order to reduce the collisions of the reservation request packets, the base station scheduler calculates the transmission probability using the number of RAS minislots and the estimated load of the reservation request packets. And it broadcasts the calculated transmission probability through the downlink control channel. Mobile terminals, which have a traffic burst, select randomly a RAS minislot and transmit the reservation request packet with the received transmission probability. The reservation request packet contains the number of packets in the buffer. The base station allocates slots based on the buffer status of the received reservation request packets.

• Journal of Digital Contents Society
• /
• v.12 no.3
• /
• pp.299-307
• /
• 2011

The MAC of IEEE 802.11 WLAN to control data transmission uses two control methods called DCF and PCF. The DCF controls the transmission based on CSMA/CA The BEB backoff algorithm of DCF shows relatively excellent performance in situation that the number of competing station is less, but has a problem that performance of throughput and delay is degraded in situation that the number of competing station is increased. This paper mathematically analyzes an MIMD backoff algorithm considering retry limit that increases the CW to doubled after collision and decreases smoothly the CW to halves after successful transmission in order to reduce the collision probability. To prove efficiency of the MIMD backoff algorithm, lots of simulations are conducted and analyzed.

• The KIPS Transactions:PartC
• /
• v.13C no.4 s.107
• /
• pp.447-454
• /
• 2006

An ad-hoc network routing protocol, AODV(Ad-hoc On-demand Distance Vector) initially uses ERS(Expanding Ring Search) algorithm to control the RREQ(Route Request) retransmission in the route discovery process. Because ERS uses the fixed NTT(Node Travesal Time), it does not reflect accurately ad-hoc network environment. In this paper, we propose an improved ERS algorithm which lowers the retransmission rate. It uses RREP(Route Reply) and gives different weights in NTT of each node in accordance with the adjacency to an originating node. To show the effectiveness of the proposed algorithm, we perform a simulation using ns2. The simulation results showed that the proposed algorithm has better performance than existing algorithms.

• Annual Conference of KIPS
• /
• 2009.04a
• /
• pp.195-199
• /
• 2009

NoC 시스템은 기본적으로 서로 다른 클럭 도메인에서 동작하는 여러 버스 시스템들이 NoC를 통해서 연결되는 것으로 간주할 수 있다. NoC에 다른 버스 인터페이스 IP를 부착하려면 별도의 래퍼를 사용해야 하며, 면적과 지연시간이 추가되는 것이 일반적이다. 본 논문에서는, 추가적인 래퍼의 필요성을 제거하기 위하여, 주어진 버스 인터페이스에 맞는 인터페이스 에이전트 또는 네트워크 인터페이스를 자동 생성하는 방법을 제안한다. 이를 위하여, 한가지 NoC 시스템을 위해 표준적인 패킷 포맷을 정의하였으며, 거기에는 패킷에 대한 라우팅 정보 뿐 아니라, 여러 종류의 버스 프로토콜의 데이터, 주소, 제어 정보도 포함될 수 있도록 정의되었다. 그리고, 인터페이스 에이전트는 표준 패킷 포맷과 특정 버스 인터페이스 프로토콜 간의 변환 작업을 수행한다. 실험을 통해서, PVCI, WISHBONE, AHB, OCP와 같은 몇 가지 버스 인터페이스에 대해 자동생성된 네트워크 인터페이스들 간에, 표준 패킷 포맷을 이용한 데이터 통신이 중요 정보의 손실 없이 잘 이루어짐을 보인다.

• Journal of the Korea Convergence Society
• /
• v.7 no.4
• /
• pp.25-32
• /
• 2016

When using reliable multicast protocol over air links, the multicast packets lost in the air link cause the initiation of retransmission request packets and the implosion of retransmission packets, which deteriorate multicast session performance. This paper proposes on the efficient reliable multicast mechanism in wireless networks utilizing the Agents. In this paper we show the design of a retransmission agent which improves the performance of reliable multicast sessions in wireless network. The main idea is to cache reliable multicast packets at the base station and perform local retransmissions across the wireless link. MATLAB has been used to simulate and to get performance results for signaling overhead and processing delay through the comparison of the proposed agent model to the Multicast File Transfer Protocol. It has been proven from the simulation results that the proxy module make pass trials shorter in Multicast File Transfer Protocol.