• Journal of Korea Multimedia Society
• /
• v.10 no.7
• /
• pp.893-901
• /
• 2007

Since real-time multimedia applications requiring duality-of-service guarantees are spreading over mobile and wireless networks, energy efficiency in wireless channels is becoming more important. Energy consumption in the channels can be reduced with decreasing the rate of scheduler's outgoing link by means of Dynamic Modulation Scaling (DMS). This paper proposes a fair queuing algorithm, termed Rate Efficient Fair Queuing (REFQ), in order to reduce the outgoing link's rate, which is based on the Latency-Optimized Fair Queuing algorithm developed to enhance Weighted Fair Queuing (WFQ). The performance evaluation result shows that REFQ does decrease the link rate by up to 35% in comparison with that in WFQ, which results in reducing the energy consumption by up to 90% when applied to the DMS based radio modem.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.10
• /
• pp.2205-2218
• /
• 1997

We implement the CARMA-M (Collision Avoidance Radio Multiple Access-Mobile) protocol and DMP (Data-radio Multiplex Protocol) with a client/server architecture for a wireless communication netowrk. These protocols support a data transfer function between a remote computer and a mobile portable computer with a wireless modem which are proposed by dataradio in U.S.A. With the review and analysis of the proposed protocol, the impelementation methods of DMP, CARMA-M and LLC to interface the protocols are presented. Moreover the FEC technique is added to find and correct the errors generated in communication. The simulation method of a wireless network using wires is also shown to verify the implemented protocols.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.158-158
• /
• 2008

In general, a wireless communication device has employed a whip antenna or a stubby antenna. Recently, wireless communication device is increasingly employing an embedded antenna, Intenna, for the sake of miniaturization. Further, it may employ both external and embedded antennas. Examples of the embedded antenna include a multi-band monopole antenna, which radiates uniformly in all directions when viewed from above, and a planar inverted F antenna (PIFA), which is a variation of the monopole antenna. However, since the conventional antenna is mounted in a finished state on the mobile communication terminal, there is a limitation of space required for providing the antenna. According to the present study, there is provided an Intenna that is deposited on a front or back case of the mobile communication terminal by a sputtering method. Accordingly, it is possible to overcome a limitation of space required for providing the Intenna and to improve the performance of the Intenna formed on the front or back case of the mobile communication terminal.

• Proceedings of the IEEK Conference
• /
• 2000.09a
• /
• pp.585-588
• /
• 2000

광대역 무선 서비스에 대한 수요가 증가함에 따라 이미 제정되었거나 현재 제정중인 무선 LAN 표준안으로는 ETSI BRAN의 HIPERLAN, IEEE 802.11, MMAC-PC등이 있다 이러한 표준안들은 상위계층은 서로 다른 반면, 5 GHz 대역에서 OFDM 방식을 사용하는 공통된 물리계층을 정의하고 있다. 본 논문에서는 이중 HIPERLAN/2 물리계층의 구조 및 파라미터를 설명하고 그 성능을 분석한다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2002.04a
• /
• pp.469-471
• /
• 2002

시스템의 복잡성, 고 비용, 표준의 미비 등 여러 요인으로 인해 가전 기기간의 데이터 통신 및 제어 정보 전송의 효율성을 만족시키지 못하고 있다. 디지털 정보 가전 간 원활한 통신을 위해 보다 안정적이고 정확한 정보 전달이 가능한 방법이 우선 보장되어야 하고, 그러기 위해서는 시스템 간의 연결을 가능하게 하는 인터페이스에 대한 분석과 연구가 선행되어야 한다. 본 논문에서는 일반적인 컴퓨터 시스템을 이용해 실제 정보 가전 제어에 적용 가능한 무선 통신 모뎀을 제시하고자 한다.

• Proceedings of the KAIS Fall Conference
• /
• 2010.11a
• /
• pp.434-437
• /
• 2010

본 논문에서는 현재 연구 개발이 활발히 진행되고 있는 공공 무선망 서비스 제공을 위한 Binary CDMA기술이 적용된 Guardian 모뎀 칩셋에 대하여 알아 본 후, 무선 데이터 전송 시험을 통해 데이터 율과 SNR, BER, PER에 대한 성능을 분석한다.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2003.10a
• /
• pp.491-494
• /
• 2003

An Automatic Water Level Measurement System has been developed in this study. It has the characteristics that it use lower power and solar power and it has the ability of sending data and remote-controlled by wireless MODEM this system was set up in the experimental site and was tested. Also, the management system for the water level data has been developed and will be used by instruments administrating reservoirs.

• Proceedings of the IEEK Conference
• /
• 2003.07a
• /
• pp.517-520
• /
• 2003

Orthogonal Frequency Division Multiplexing (OFDM) is a promising technology for high speed multimedia communication in a frequency selective multipath channel. In this paper, Software IPs for the synchronizer of IEEE 802.11a Wireless LAN system are designed and optimized for TI's TMS320C6201 fixed point DSP. As a result of the execution cycles of the target DSP for each functions of the system, an efficient HW/SW partitioning method can be considered.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.2A
• /
• pp.128-137
• /
• 2006

In this paper, we propose a wireless network discovery scheme which support effective device power management by employing battery efficient network scanning procedure. Multi-mode terminals need to discover other wireless systems, above all, to execute an inter-system handover in the environment of heterogeneous wireless networks. The existing methods introduced in some recent research reports have certain shortcomings, such as battery power consumption increased by frequent modem activation, or the multi-mode terminal's inability to promptly discover wireless system. We Propose a scheme in which multi-mode terminals more quickly and accurately discover other wireless systems than previous schemes, while consuming minimum power. It also proves that the scheme has better performance by comparing it with the existing schemes.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2001.10b
• /
• pp.935-938
• /
• 2001

휴대용 컴퓨터의 폭넓은 보급으로 인해 사용자의 이동성을 살린 무선 정보망의 실현 수단으로서 무선 LAN 에 대한 관심이 급증하고 있다. 무선 LAN 이 향후 정보 통신 기반구조로 자리하기 위해서는 사용자의 이동성을 보장하기 위한 효과적인 로밍 기술이 절대적이다. 본 논문에서는 현재 표준화가 진행중인 IEEE 802.1X를 기반으로 하여 무선 LAN 환경에서 사용자의 안전한 이동성 보장을 위한 서로 다른 도메인 간의 단말 이동을 지원하는 로밍 보안 방법론을 제안한다. 인증 및 키교환 메커니즘은 EAP-TLS 를 기준으로 하며, 로밍이 발생할 때 TLS 의 핸드쉐이크 과정을 단순화하는 접근을 사용한다.