• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.3
• /
• pp.161-168
• /
• 2011

This paper provides the performance measurement and analysis of Wireless LAN IEEE 802.11 in a mobile environment. The performances of IEEE802.11b/g and IEEE802.11p designed for Vehicle-to-Vehicle(V2V) communication are measured and analyzed. Diameter of communication and link access time are compared under variation of speed of the vehicle.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.63 no.3
• /
• pp.195-199
• /
• 2014

Various M2M applications have different quality-of-service(QoS) requirements to be implemented practically. QoS requirements are normally data rate and delay constraint. However, there are limited number of wireless communication chip solutions which cannot support QoS requirements for all M2M application. Hence, aggregated usage of plural wireless communication chip solutions should be needed to implement M2M applications. In this paper, we consider the case that two wireless communication chips using random access protocol work together to transmit data of an M2M application. In such case, data rate and delay performance are mathematically analyzed. In our results, practical data rate can be improved from 2.5 to 7 times while delay constraints are satisfied if we simply use two wireless communication chips together.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.10A
• /
• pp.816-822
• /
• 2011

This paper provides the performance measurement and analysis of Wireless LAN IEEE 802.11 in a mobile environment. The performance of IEEE802.11b/g and IEEE802.11p that is designed for Vehicle-to-Vehicle(V2V) communication is measured and analyzed. Diameter of communication, link access time and delay are measured as vehicle's speed varies. Also, the performance is checked in a situation that the load to network varies. In conclusion, the futher research topics are discussed.

• ETRI Journal
• /
• v.31 no.5
• /
• pp.601-603
• /
• 2009

This letter presents a high performance 2.4 GHz two-stage power amplifier (PA) operating in the temperature range from $-30^{\circ}C$ to $+85^{\circ}C$ for IEEE 802.11g, wireless local area network application. It is implemented in InGaP/GaAs hetero-junction bipolar transistor technology and has a bias circuit employing a temperature compensation technique for error vector magnitude (EVM) performance. The technique uses a resistor made with a base layer of HBT. The design improves EVM performance in cold temperatures by increasing current. The implemented PA has a dynamic EVM of less than 4%, a gain of over 26 dB, and a current less than 130 mA below the output power of 19 dBm across the temperature range from $-30^{\circ}C$ to $+85^{\circ}C$.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.4
• /
• pp.923-948
• /
• 2013

The main concern in mobile peer-to-peer (P2P) networks is security because jamming or eavesdropping on a wireless link is much easier than on a wired one and such damage can be incurred without physical access or contact. In particular, authentication has increasingly become a requirement in mobile P2P environments. This paper presents a new mutual authentication mechanism which requires less storage space and maintains a high level of security in mobile P2P networks. The proposed mechanism improves efficiency by avoiding the use of centralized entities and is designed to be agile in terms of both reliability and low-cost implementation. The mechanism suggested in the simulation evaluates the function costs occurring in authentication between the devices under mobile P2P network environment comparing to existing method in terms of basic operation costs, traffic costs, communications costs, storage costs and scalability. The simulation results show that the proposed mechanism provides high authentication with low cryptography processing overhead.

• Smart Structures and Systems
• /
• v.7 no.2
• /
• pp.83-102
• /
• 2011

As a testbed for various structural health monitoring (SHM) technologies, a super-tall structure - the 610 m-tall Guangzhou Television and Sightseeing Tower (GTST) in southern China - is currently under construction. This study aims to explore state-of-the-art wireless sensing technologies for monitoring the ambient vibration of such a super-tall structure during construction. The very nature of wireless sensing frees the system from the need for extensive cabling and renders the system suitable for use on construction sites where conditions continuously change. On the other hand, unique technical hurdles exist when deploying wireless sensors in real-life structural monitoring applications. For example, the low-frequency and low-amplitude ambient vibration of the GTST poses significant challenges to sensor signal conditioning and digitization. Reliable wireless transmission over long distances is another technical challenge when utilized in such a super-tall structure. In this study, wireless sensing measurements are conducted at multiple heights of the GTST tower. Data transmission between a wireless sensing device installed at the upper levels of the tower and a base station located at the ground level (a distance that exceeds 443 m) is implemented. To verify the quality of the wireless measurements, the wireless data is compared with data collected by a conventional cable-based monitoring system. This preliminary study demonstrates that wireless sensing technologies have the capability of monitoring the low-amplitude and low-frequency ambient vibration of a super-tall and slender structure like the GTST.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.8 s.350
• /
• pp.91-96
• /
• 2006

High efficiency switching mode circuits such as class I amplifiers have been well known in the MHz frequency range. The class E amplifier is a type of switching mode amplifier offering very high efficiency approaching 100%. In this paper, the class E amplifier has been designed by using the harmonic balance method of circuit simulator. The designed amplifier is realized by using pHEMT and microstrip line, shows 66% power added efficiency (PAE) at 2.4GHz with 17.6dBm output power. With -3dBm input power of wireless LAN, measured output spec01m can meet the required IEEE 802.11g standard spectrum mask. That means the required amplifier back off of 9dB from $P_{ldB}$ to satisfy the required wireless LAN spectrum mask.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.7
• /
• pp.1407-1411
• /
• 2005

Tn these server oriented network forms, users allowed to approach the a certain server only in slave and passive way, and are limited in sharing informations, and internet choose from a method of traditional centralized web server until now, so we pay a lot of money and have a problem of maintenance management. The P2P is the new solution of these limitations, but there is no verification about the possibility and validity of p2p as the business model. This parer offering to some solution for those problems using the JXTA technique and P2P compution. We will apply the JXTA platform that wireless environment as mobile environment. The JXTA technique can be interoperability between third-party. This paper is implementation of P2P communication system on mobile environment. It's implementation used by JXTA technique, J2ME and XML.

• Proceedings of the Korean Information Science Society Conference
• /
• 2007.10d
• /
• pp.312-316
• /
• 2007

정보통신 기술의 전으로 디지털 콘텐츠분야는 혐의의 문화산업에서 벗어나 범 산업에 공통되는 요소로써 자리매김하고 있다. 디지털 콘텐츠의 급속한 양적 팽창은 콘텐츠의 저작권 보호 문제와 직접적인 충돌을 야기하고 있다. 특히, 저장된 MP3 음악 파일 재생하는 MP3 플레이어가 확산되면서 MP3 음악 파일의 무단 복제로 인한 저작권 침해 문제는 매우 심각하다. 본 논문에서는 이러한 문제를 해결하고 유비쿼터스 환경에 적합한 응용 기기로써 실시간 멀티미디어 재생기, SMP(Streaming Multimedia Player)를 설계한다. SMP는 WiBro 망을 통해 스트리밍 방식으로 음악을 전송받아 재생하는 휴대용 MP3 플레이어로써 저렴한 월정액의 저작권 및 통신요금으로 언제 어디서나 원하는 음악을 서비스 받을 수 있는 유비쿼터스 단말이다. 본 논문에서는 SMP 단말을 설계하고 WiBro 망과 P2P 통신을 이용한 서비스 연결 방식과 콘텐츠 제공 방식을 제안하고 분석한다.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.49 no.12
• /
• pp.81-88
• /
• 2012

As the performance of the next-generation broadband wireless networks is dramatically enhanced, various services (i.e., education, Live video streaming, Live video conferencing, online games, etc.) have been provided to users through a smart mobile platform. Those services are usually provided by using the centralized communication server. However, since all multimedia traffic is exchanged through a communication server, it often has the scalability problem with regard to traffic management. Our main purpose is for group smart users to provide scalable live multimedia streaming service based on P2P network. To do this, we have designed an architecture of P2P-based service management for mobile group communication management and service management protocol. In order to verify the performance of the proposed scheme, we have mathematically analyzed the performance in terms of the average transmission delay and bandwid th utilization.