• Journal of Information Technology Applications and Management
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• v.10 no.2
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• pp.61-71
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• 2003

Ad-hoc networks are characterized by multi-hop wireless links, frequently changing network topology and the need for efficient dynamic routing protocols. In an Ad-hoc network, each host assumes the role of a router and relays packets toward final destinations Because a packet is broadcast to all neighboring nodes, the optimality criteria of wireless network routing is different from that of wired network routing. tn this paper 1 point out the more important cost factor than the number of links in the Ad-hoc network. A class routing protocols called on-demand protocols has recently found attention because of their low routing overhead since it performs a blind flooding to look for a path. In this paper, 1 propose the method which reduces overhead by using the information of neighboring nodes and doing a selective flooding. Simulation results demonstrate better reduction of routing overheads with this scheme.

• Broadcasting and Media Magazine
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• v.12 no.3
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• pp.14-36
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• 2007

다양한 무선 통신 서비스의 등장으로 주파수 자원의 수요가 급증하여 스펙트럼 이용 효율을 극대화하기 위한 새로운 기술 개발의 필요성이 대두되고 있으며, 이에 대한 기술로 Cognitive Radio (CR) 기술이 주목받고 있다. CR 기술은 선택된 주파수 대역에 최적의 QoS를 제공하기 위해서는 먼저 주파수 환경에 적응성을 갖는 스펙트럼 센싱 (Spectrum Sensing) 기술이 필요하며, CR 기술이 적용된 무선 브로드밴드 네트워크 (AWBN : Adaptive Wireless Broadband Network) 모듈은 최근 각광받고 있는 방통융합 솔루션의 Hot Issue인 QoS 보장 홈네트워크 기반의 멀티미디어 전송(TV Portal Service)용 네트워크에 최적화된 솔루션으로 활용될 것으로 기대하고 있을 뿐만 아니라, IEEE 802.22 그룹에서 연구되고 있는 비어있는 TV 대역 및 마이크로폰 대역에 활용될 뿐만 아니라, 기존의 Mobile WiMax에 의한 브로드밴드 네트워크에도 활용 가능하다. 본 고에서는 IEEE 802.22/16d 시스템 규격에 의해 개발된 AWBN 시스템 개발 내용을 기술한다.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.121-124
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• 1999

In a packet-switched wireless cellular network, a packet destined to a mobile station is queued at a base station and then broadcast over the base station's cell. When an active mobile station leaves a cell, there re-main packets which are destined to the mobile and not yet delivered to it at the cell's base station. For application which are sensitive to packet losses, such back- logged packets must be forwarded to the new base station. Otherwise, an end-to-end retransmission may be required. However, an increase in packet delay is incurred by employing the packet forward scheme, since a packet may be forwarded many times before it is delivered to the destined mobile station. For an enhanced quality-of-service level, it is preferred to reduce tile packet delay time. In this paper, we develop an analytical approximation method for deriving mean packet delay times. Using the approximation and simulation methods, we investigate the effect of network parameters on the packet delay time.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.253-256
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• 2001

This paper describes a high speed MAC(Media Access Control) function chip for IEEE 802.11 MAC layer protocol. The MAC chip has control registers and interrupt scheme for interface with CPU and deals with transmission/reception of data as a unit of frame. The developed MAC chip is composed of protocol control block, transmission block, and reception block which supports the BCF function in IEEE 802.11 specification. The test suite which is adopted in order to verify operation of the MAC chip includes various functions, such as RTS-CTS frame exchange procedure, correct IFS(Inter Frame Space)timing, access procedure, random backoff procedure, retransmission procedure, fragmented frame transmission/reception procedure, duplicate reception frame detection, NAV(Network Allocation Vector), reception error processing, broadcast frame transmission/reception procedure, beacon frame transmission/reception procedure, and transmission/reception FIEO operation. By using this technique, it is possible to reduce the load of CPU and firmware size in high speed wireless LAN system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1B
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• pp.39-45
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• 2006

In this paper, existing technology that uses broadcasting and multicasting IP addrsses at the wireless access network, based on Internet as a core network, is upgraded. By employing broadcasting service request by receivers, convergence of multicasting and broadcasting, and lower level filtering of broadcast data, the load and traffic of network, server, base station, and receiver is substantially reduced. The technology proposed in this paper could be useful for general broadcasting services, and especially optimum for LBS and Telematics services.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.799-801
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• 2012

Wireless Mesh Network (WMN) can be defined as a communication network consisting of radio nodes organized in a mesh topology, which has been attracting much attention due to its promising technology. This paper addressed the factors on how to design routing protocols for WMN. 2 examples of designing routing metric and routing algorithm are given for case study. With consideration of those factors such as wireless broadcast advantage (WBA)/channel assignment (CA) or intra-flow/inter-flow interference high throughput is achieved.

• International journal of advanced smart convergence
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• v.12 no.1
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• pp.1-8
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• 2023

Smart IoT over high speed network and high performance smart devices explodes the ubiquitous services and applications. Nearest Neighbor(NN) query is one of the important type of queries that have to be supported for ubiquitous information services. In order to process efficiently NN queries in the wireless broadcast environment, it is important that the clients determine quickly the search space and filter out NN from the candidates containing the search space. In this paper, we propose a hybrid index of Voronoi and grid partition to provide quick search space decision and rapid filtering out NN from the candidates. Grid partition plays the role of helping quick search space decision and Voronoi partition providing the rapid filtering. We show the effectiveness of the proposed index by comparing the existing indexing schemes in the access time and tuning time. The evaluation shows the proposed index scheme makes the two performance parameters improved than the existing schemes.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.700-702
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• 2003

무선 ad­hoc 네트워크에서는 기존의 유선 네트워크와 달리 기반 시설 없이 휴대용 기기들만으로 네트워크가 형성된다. 휴대용 기기들은 배터리를 에너지원으로 사용하므로 효율적인 에너지 자원 관리가 중요한 고려 대상이 된다. 본 논문에서는 ad­hoc 무선 네트워크에서 전체 에너지를 적게 사용하는 브로드캐스트 라우팅 트리를 형성하는 알고리즘을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.11a
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• pp.11-14
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• 2004

기존의 다양한 무선인터넷 플랫폼이 WIPI(Wireless Internet Platform for Interoperability)라는 무선인터넷 플랫폼으로 표준화되면서 플랫폼 간 컨텐츠 호환성을 보장하고, 플랫폼의 이식의 용이성을 제공하여 다양하고 풍부한 컨텐츠들이 개발되고 있다. 본 논문에서는 다양한 어플리케이션간에 데이터를 교환하고 공유하기 편리한 XML 데이터를 생성하고, 실시간으로 야구 중계 서비스를 제공하는 시스템을 설계 및 구현하였다. 이러한 데이터서비스 교환에 XML을 적용함으로써 클라이언트와 서버 사이의 통신을 표준화하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.11 s.353
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• pp.118-127
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• 2006

The wireless transmission medium inherently broadcasts a signal to all neighbor nodes in the transmission range. Existing asynchronous MAC protocols do not provide a concrete solution for reliable broadcast in link layer. This mainly comes from that an omnidirectional broadcasting causes to reduce the network performance due to the explosive collisions and contentions. This paper proposes a directional broadcast protocol by using neighborhood information in the link layer based o,1 directional antennas, named MNDB (MAC protocol with Neighborhood for reliable Directional Broadcast). This protocol makes use of neighborhood information and DMACA (Directional Multiple Access and Collision Avoidance) scheme through 4-way handshake to support a reliable directional broadcast. To analyze its performance, MNDB protocol si compared with $RMDB^{[1]}$, the protocol 2 of reference [3], and IEEE 802.11 $protocol^{[9]}$, in terms of the number of collisions, the number of dropped packets, the number of redundant packets, and broadcast delay.