• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4B
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• pp.245-257
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• 2012

As one of the most challenging tasks in designing the Internet routers, packet classification is required to achieve the wire-speed processing for every incoming packet. Packet classification algorithm which applies binary search on trie levels to the area-based quad-trie is an efficient algorithm. However, it has a problem of unnecessary access to a hash table, even when there is no node in the corresponding level of the trie. In order to avoid the unnecessary off-chip memory access, we proposed an algorithm using Bloom filters along with the binary search on levels to multiple disjoint tries. For ACL, FW, IPC sets with about 1000, 5000, and 10000 rules, performance evaluation result shows that the search performance is improved by 21 to 33 percent by adding Bloom filters.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1754-1766
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• 2015

Packet classification carried out in Internet routers is one of the challenging tasks, because it has to be performed at wire-speed using five header fields at the same time. In this paper, we propose a leaf-pushed AQT bitmap trie. The proposed architecture applies the leaf-pushing to an area-based quad-trie (AQT) to reduce unnecessary off-chip memory accesses. The proposed architecture also applies a bitmap trie, which is a kind of multi-bit tries, to improve search performance and scalability. For performance evaluation, simulations are conducted by using rule sets ACL, FW, and IPC, with the sizes of 1k, 5k, and 10k. Simulation results show that the number of off-chip memory accesses is less than one regardless of set types or set sizes. Additionally, since the proposed architecture applies a bitmap trie, the required number of on-chip memory accesses is the 50% of the leaf-pushed AQT trie. In addition, our proposed architecture shows good scalability in the required on-chip memory size, where the scalability is identified by the stable change in the required memory sizes, as the size of rule sets increases.

• Journal of Internet Computing and Services
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• v.10 no.2
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• pp.15-28
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• 2009

This paper proposes HWbF(Hit and WLC based Firewall) design which consists of an PFS(Packet Filter Station) and APS(Application Proxy Station). PFS is designed to reduce bottleneck and to prevent the transmission delay of them by distributing packets with PLB(Packet Load Balancing) module, and APS is designed to manage a proxy cash server by using PCSLB(Proxy Cash Server Load Balancing) module and to detect a DoS attack with packet traffic quantity. Therefore, the proposed HWbF in this paper prevents packet transmission delay that was a drawback in an existing Firewall, diminishes bottleneck, and then increases the processing speed of the packet. Also, as HWbF reduce the 50% and 25% of the respective DoS attack error detection rate(TCP) about average value and the fixed critical value to 38% and 17%. with the proposed expression by manipulating the critical value according to the packet traffic quantity, it not only improve the detection of DoS attack traffic but also diminishes the overload of a proxy cash server.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2263-2268
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• 2015

This paper describes packet scheduling techniques that can be used to alleviate the impact of interference. The mechanism is consisted of interference estimation and master delay police. Proposed scheduling police is effective in reducing packet loss and delay. Another advantage worth mentioning, are the additional saving s in the transmitter power since packet are not transmitted when channel is bad. This paper gives that scheduling policy works only with data traffic since voice packets need to be sent at fixed intervals. However, if the delay variance is constant and the delay can be limited to a slot, it may be worthwhile to use DM packet for voice.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05b
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• pp.1369-1372
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• 2003

가까운 장래에 싼 가격의 블루투스가 여러 가지 이동, 휴대 장치에 내장되어 다양한 응용서비스를 제공할 것이다. 본 논문에서는 공항이나 쇼핑몰 등 사람들이 많이 몰리는 공공장소와 같은 핫스팟(hot spot) 지역에서 블루투스 기지국을 통한 음성서비스 제공을 위하여 다수의 기지국을 유서 LAN으로 협동시켜 각각 기지국별로 따로 제공되던 음성 채널들을 집합화(aggregation) 함으로써 보다 많은 음성 서비스 채널들을 동시에 수용할 수 있는 방법을 제시하고 성능을 분석하였다. 단독으로 동작하는 기지국은 ACL채널을 사용하는 경우 7개까지의 채널 수용이 가능하므로 이상적인 경우에서도 오버랩 영역의 기지국의 개수가 n이면 7n 만큼 채널의 증가가 가능한 반면 협동으로 동작하면 블록킹 율도 개선되면서 집합화된 채널들을 보간(interpolation) 기법을 통한 통계적 사용으로 음성 패킷의 허용 손실 범위 내에서 음성채널의 수를 약 14n 정도까지 확장할 수 있다. 또한 음성전송과 데이터 전송이 혼합 서비스 될 때 수용하는 음성 채널의 수에 따른 데이터 전송지연시간 특성을 분석하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3B
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• pp.112-122
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• 2008

Basing on Piconet, The Bluetooth System forms network and transmits data. There is one Master and maximum 7 Slave bluetooth devices in one piconet. A job scheduler performed by Master bluetooth device, gives the chance of data transmission to Slave bluetooth devices, which connected to Master, using polling method in piconet. The maximum data rate is 723.2 kb/s when it uses ACL link with DH5 packet type in a piconet which is constructed by two bluetooth devices. However, if there are one master and two slave devices in a piconet, then the maximum data rate is reduced to a half(361.6kb/s), because a master device has to support same data rate for all connected devices. And, there is the defect in scatternet when data transmission rate becomes low(Maximum rate: 302.2kb/s). This paper proposals the new ad-hoc network topology called "DoublePico"for overcome the low data transmission in scatternet which is constructed by piconets. The method of doublepico that represented in this paper makes high data transfer rate(Maximum rate: 457.57kb/s) in bluetooth ad-hoc networks.