• 한국통신학회논문지
• /
• 제22권1호
• /
• pp.151-161
• /
• 1997

In this paper we designed a high speed wireless multiple access protocol, which is suitable for future multimedia wireless LAN systems which support high quality video teleconferencing, telephony and graphic databases. In the proposed protocol, Slotted-ALOHA protocol is used for transmitting random data packets and the packet reservation multiple access(PRMA) protocol for transmitting periodic data packets. The use of minislot is introduced for the reservation scheme. In order to measure the performance characteristic of the proposed protocol, a simulator is designed using an object oriented programming language, C++, and an exhaustive simulation study is carried out. From the simulation results, it is observed that the proposed protocol and the existing PRMA protocol have almost the same delay characteristic when network traffic is low. However, the proposed protocol is superior to the PRMA protocol when traffic becomes higher. The proposed protocol and the results can be utilized for the design of the wireless access systems and future broadband wireless LANs.

• 한국정보통신설비학회:학술대회논문집
• /
• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
• /
• pp.208-210
• /
• 2009

Currently, Wireless LAN(WLAN) service is widely deployed to provide high speed wireless Internet access through the mobile stations such as notebook and PDA. To provide enhanced security and user access control in the public WLAN area, WLAN access points should have the capability of IEEE 802.1x-based user authentication and authorization functionality. In this paper, we provide a brief understanding of IEEE 802.1x standards and related protocols like EAPOL(Extended Authentication Protocol Over LAN), EAP, RADIUS and describe how the IEEE 802.1x is designed and implemented in our embedded linux-based WLAN AP which is named i-WiNG. (Intelligent Wireless Internet Gateway). For the network security and user authenti -cation purposes, a supplicant who wants to access Internet should be authorized to access the AP port using the EAPOL.

• 한국항행학회논문지
• /
• 제10권3호
• /
• pp.268-275
• /
• 2006

가정과 사무실 정보 응용 및 서비스의 급격한 확산은 광대역 근거리 멀티미디어 통신을 가능하게 하는 새로운 무선 기술을 필요로 하고 있다. 고품질 미디어와 고속의 무선 연결을 위한 요구에 의하여 IEEE 표준화 그룹은 WPAN을 위한 고속 물리 계층을 고려하고 있다. 협대역의 펄스 전송을 기반으로 하는 UWB 다중 접속 기술은 고속의 서비스 제공, 낮은 전력 소모, 정확한 측위를 제공할 수 있는 응용 중의 하나이다. 본 논문에서는 전력 제어된 UWB 디바이스로 구성된 무선 센서 네트워크에서 페이딩 환경에 대한 UWB의 BER 성능을 평가하기 위한 방법론을 제시한다. 얻어진 결과는 주어진 네트워크 구조에 따른 성능 분석을 위하여 사용될 수 있으며 UWB 홈 센서 네트워크를 위한 유용한 디자인 아이디어를 제공할 수 있다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.778-781
• /
• 2005

In this paper, we describe a development of a Bluetooth Access Point for the WAN connection of home network devices. Especially, users can access the PSTN at home instead of expensive digital cellular network through the AP, using the 'one-phone', which is the Bluetooth enabled cellular phone. The simultaneous benchmark test about telephone service and LAN access service shows the perfect compatibility and reasonable performance of the access point. The one-phone service can become a convergence of wired and wireless communication through the AP.

• 융합보안논문지
• /
• 제4권2호
• /
• pp.53-60
• /
• 2004

본 논문에서는 무선 인터넷 환경에서 CHAP 인증 기법을 이용한 로밍 서비스 지원 방법을 기술한다. 이를 위해 특별히 GPRS 망으로 이동한 이동 ISP 망 가입자가 자신의 홈 ISP 망을 접속하여 인증을 받기 위한 기법을 제시한다 또 이동 ISP 망 가입자의 단말에서 정의되어야 할 인증 메시지 구조와 GPRS 망 게이트웨이에서 구현될 메시지 구조를 제시한다. 아울러 GGSN과 ISP 망간의 인증 메시지 구조를 정의하며 이들 제안된 내용에 대해 시험 환경 구축을 통해 실제 시뮬레이션 결과를 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제12권3호
• /
• pp.1031-1046
• /
• 2018

Vehicular ad hoc network (VANET) is a dedicated network to connect vehicles without any centralized administration or infrastructure. The wireless access in vehicular environments (WAVE) protocol leveraging IEEE 1609/802.11p is widely implemented for VANETs. However, in congested traffic situation, the performance of the WAVE system degrades significantly due to serious collision, especially for safety related broadcast services on the control channel (CCH) interval due to the inherent drawback of its collision avoidance mechanisms called carrier sense multiple access with collision avoidance (CSMA/CA). In this paper, we propose a method that can decrease the number of frame collisions in CCH with a few modifications to the IEEE 802.11p protocol. In the paper, vehicles still employ CSMA/CA to compete for the channel access opportunity. However, by taking advantage of periodicity of synchronization interval, a two-state switching scheme introducing two new inter frame space (IFS) is proposed to reduce the number of competing vehicles substantially and as a result, the collision probability is significantly decreased. The simulation results demonstrate the superiority of the proposed method in packet collision rate.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권5호
• /
• pp.2646-2659
• /
• 2017

Equipped with the advantages of flexible access control and fine-grained authentication, attribute based signcryption is diffusely designed for security preservation in many scenarios. However, realizing efficient key evolution and reducing the calculation costs are two challenges which should be given full consideration in attribute based cryptosystem. In this paper, we present a key-policy attribute based signcryption scheme (KP-ABSC) with delegated computation and efficient key updating. In our scheme, an access structure is embedded into user's private key, while ciphertexts corresponds a target attribute set. Only the two are matched can a user decrypt and verify the ciphertexts. When the access privileges have to be altered or key exposure happens, the system will evolve into the next time slice to preserve the forward security. What's more, data receivers can delegate most of the de-signcryption task to data server, which can reduce the calculation on client's side. By performance analysis, our scheme is shown to be secure and more efficient, which makes it a promising method for data protection in data outsourcing systems.

• ETRI Journal
• /
• 제37권3호
• /
• pp.480-490
• /
• 2015

The reliability of sensor networks is generally dependent on the battery power of the sensor nodes that it employs; hence it is crucial for the sensor nodes to efficiently use their battery resources. This research paper presents a method to increase the reliability of sensor nodes by constructing a connected dominating tree (CDT), which is a subnetwork of wireless sensor networks. It detects the minimum number of dominatees, dominators, forwarder sensor nodes, and aggregates, as well as transmitting data to the sink. A new medium access control (MAC) protocol, called Homogenous Quorum-Based Medium Access Control (HQMAC), is also introduced, which is an adaptive, homogenous, asynchronous quorum-based MAC protocol. In this protocol, certain sensor nodes belonging to a network will be allowed to tune their wake-up and sleep intervals, based on their own traffic load. A new quorum system, named BiQuorum, is used by HQMAC to provide a low duty cycle, low network sensibility, and a high number of rendezvous points when compared with other quorum systems such as grid and dygrid. Both the theoretical results and the simulation results proved that the proposed HQMAC (when applied to a CDT) facilitates low transmission latency, high delivery ratio, and low energy consumption, thus extending the lifetime of the network it serves.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권10호
• /
• pp.3789-3809
• /
• 2015

In this paper, we deal with the problem of M2M gateways' network selection for different types of M2M traffic in heterogeneous wireless networks. Based on the difference in traffic's quality of service (QoS) requirements, the M2M traffic produced by various applications is mainly classified as two categories: flexible traffic and rigid traffic. Then, game theory is adopted to solve the problem of network-channel selection with the coexistence of flexible and rigid traffic, named as flexible network access (FNA). We prove the formulated discrete game is a potential game. The existence and feasibility of the Nash equilibrium (NE) of the proposed game are also analyzed. Then, an iterative algorithm based on optimal reaction criterion and a distributed algorithm with limited feedback based on learning automata are presented to obtain the NE of the proposed game. In simulations, the proposed iterative algorithm can achieve a near optimal sum utility of whole network with low complexity compared to the exhaustive search. In addition, the simulation results show that our proposed algorithms outperform existing methods in terms of sum utility and load balance.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2012년도 추계학술대회
• /
• pp.394-397
• /
• 2012

무선센서네트워크는 각종 센서에서 수집한 현실세계 환경 정보를 무선으로 수집할 수 있도록 구성한 네트워크이다. 현재, 다양한 방법으로 무선센서네트워크에서 수집한 정보가 활용되고 있는데, 본 논문에서는 무선센서네트워크에서 수집된 정보를 증강현실(Augmented Reality)을 사용하여 현실 세계에 데이터를 투영함으로써, 보다 직관적인 정보를 사용자에게 제공하고자 한다. 본 논문에서는 무선센서네트워크에서 수집된 정보를 DB테이블에 저장하고, 센서필드에 배치된 무선LAN(Access Point)과 단말기에 부착된 지자기센서, 가속도 센서를 이용하여 단말기 위치를 보정한 후, 증강현실을 이용하여 DB 테이블에 저장된 데이터를 시각화 하는데 그 목적이 있다.