• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.10a
• /
• pp.108-111
• /
• 2009

In this paper, the development of unmanned vehicle systems to analysis applicable communications and alternative IEEE 802.11a. IEEE 802.11b/g uses the 2.4GHz. So, using the 5GHz OFDM in IEEE 802.11a interference phenomenon better. IEEE 802.11a has a maximum speed of 54Mbps. Indoors and apartment parking on experiment to soft roaming, hard roaming. Test equipments are AP four units(RSU), reliable results for the AP one unit Bridge, Switch one unit, one server notebook, one notebook(OBU), one car. Use Softwares are Wireshark, Jperf, Ping and million second transfer was used to develop the program. So the actual car was similar to the environment. With the results of the experiment for the unmanned vehicle systems will provide the best method.

• Proceedings of the Korean Information Science Society Conference
• /
• 2003.04d
• /
• pp.316-318
• /
• 2003

본 논문에서는 무선랜 프로토콜 IEEE802.11g에서 사용되는 변조방식인 OFDM (Orthogonal frequency division multiplexing) 방식을 TMX320C6416을 사용하여 구현하였다. 통신 시스템의 발달에 따라 고속으로 데이터를 전송하는 방식이 요구되었고, 유선망 없이 장소에 구애 받지 야고 데이터를 송수신할 수 있는 무선랜 시스템의 필요성이 증가하고 있다. 이러한 필요성에 따라 2002년 6월 현재 발표된 IEEE 802.11g 규격 Draft 2.8은 2.4GHz 주파수 대역에서 기존 IEEE 802.11b규격과 호환성은 유지하며 전송속도를 최소 20Mbps 이상을 목표로 한다. IEEE802.119에 정의된 규정에 따라 OFDM방식의 기저대역 알고리즘을 TMX320C6416 을 사용하여 각 블록별로 C언어로 구현하였고, TMX320C6416에 대한 리니어 어셈블리 언어로 구현하는 최적화 작업을 통해 연산속도를 향상시키는 것을 목적으로 하며, 구현한 알고리즘의 비트 오류 확률을 매트랩 시뮬레이션 결과와 비교해 보도록 한다.

• Journal of Korean Institute of Industrial Engineers
• /
• v.37 no.2
• /
• pp.89-95
• /
• 2011

The distributed coordination function (DCF) and point coordination function (PCF) protocols are the basic MAC protocols for legacy IEEE 802.11, IEEE 802.11a, IEEE 802.11b, IEEE 802.11e, IEEE 802.11g and IEEE 802.11n wireless LANs. When the DCF protocol is used for the various versions of IEEE 802.11 wireless LANs, the MAC performance seriously degrades due to the collisions among the stations (STAs) as more and more STAs attempt to transmit their data frames. On the other hand, the PCF MAC performance becomes poor when many STAs exist in IEEE 802.11 wireless LANs, however, only small number of STAs actually attempt to transmit their data frames. In this paper, we propose the algorithm for improving the MAC performance by selectively using the DCF and PCF protocols according to the state of IEEE 802.11 wireless LANs. Numerical examples are presented to show the MAC performance improvement by the selective use of the DCF and PCF protocols according to the network state.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.12B
• /
• pp.1996-2002
• /
• 2000

This paper investigates a priority scheme for IEEE 802.11 Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol in order to provide short access times for priority frames (e.g. time-deadline traffic) even when the overall traffic on the wireless channel is heavy. Under the compatibility constraint for the IEEE 802.11 wireless LANs, two priority systems are simulated: no priority (current IEEE 802.11 standard) for time-deadline traffics and dynamic time-deadline priority. We evaluate algorithms to improve the time-deadline traffic performance using discrete event simulation (DES)

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.4
• /
• pp.837-846
• /
• 2013

Recently, new technologies based on wireless LAN is being studied because utilization on smart phone using Wi-Fi is increased. 802.11 b/g/a is universalized wireless LAN technologies based on ISM, the standard developed in 11's working group of IEEE 802. standardization about IEEE 802.11ac that overcame limitation on Blue-ray of IEEE 802.11n or uncompressed video transmission and IEEE 802.af's technologies using TVWS is being actively studied. In this paper, ability of transmission considering the security on AP operated by these technologies have measured and done a comparative analysis with existing wireless LAN environment ability of transmission measured when appling security is more stable than existing ability of transmission in an environment with obstacles and shorten of transmission time is confirmed as a result of analysis.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.8
• /
• pp.1613-1621
• /
• 2015

This paper analyzes the rate adaptation scheme and suggests applicable strategy of the MCS(Modulation and Coding Scheme) for improving DCF throughput in the IEEE 802.11ad and 802.11ad wireless LAN. IEEE 802.11ac and 802.11ad wireless LAN provide MCS technique that dynamically adjusts modulation level and code rate to the time-varying channel conditions in order to obtain considerably high data rates. But these standards did not provide rate adaptation algorithm, so this paper surveyes rate adaptation algorithm and suggests MCS scheme applied to IEEE 802.11ac and 802.11ad wireless LAN. Specially A MAC(Medium Access Control) layer throughput is evaluated over error-prone channel in the IEEE 802.11ac-based wireless LAN. In this evaluation, DCF (Distributed Coordination Function) protocol and A-MPDU (MAC Protocol Data Unit Aggregation) scheme are used. Using theoretical analysis method, the MAC saturation throughput is evaluated with the PER (Packet Error Rate) on the condition that the number of station, transmission probability, the number of parallel beams and the number of frames in each A-MPDU are variables.

• Proceedings of the IEEK Conference
• /
• 2003.11c
• /
• pp.187-190
• /
• 2003

최근 IEEE에서 WLAN을 표준으로 하는 802.11g가 확정되면서 이를 지원하는 AP가 출시되었다. AP에서 사용되는 OS는 POSIX를 기반으로 된 Linux 같은 OS를 통하여 구현되고 있 다. 이 논문에서는 가장 범용으로 사용되고 있는 Rad Hat을 기반으로 한 embeded linux를 만들어본다. 이와 함께 embeded linux를 가지고서 Network 기능을 추가하고, AP 하드웨어 드라이버 및 AP 모듈을 올려서 구연한다. 여기에 추가적으로 DHCP나 Web UI기능 등의 부가 기능을 추가하여 AP를 구현하는데 목적이 있다.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.42 no.3 s.333
• /
• pp.39-44
• /
• 2005

The OFDM modulation and transmission block have been modeled in order to analyse the relationship between the 2.4GHz power amplifier distortion and output ACPR for the IEEE 802.11g wireless LAN. The nonlinear characteristic of the power amplifier has been modeled as AM-to-AM and AM-to-PM using the behavioral model, and the output spectrum is analysed with the phase distortion variation. Also, amplifier back-off value from P1dB to satisfy the required IEEE 802.11g standard spectrum mask s been simulated with modeled phase distortion, and the simulation data have been compared to the measured result by using the pre-distortion technique.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2023.01a
• /
• pp.423-424
• /
• 2023

4차 산업 시대로 진화하면서 스마트 홈 솔루션 개발이 활발히 진행 중이며 스마트 벽스위치에 대한 적용 사례가 증가하고 있다. 가격 경쟁력을 통해 시장을 선점하고 있는 중국 제품은 대부분 블루투스와 지그비 통신 방식의 스위치를 사용하고 있다. 하지만, 지그비 통신은 저전력인데 반해 블루투스보다 통신속도가 늦고 별도의 허브를 통한 네트워크 구성이 추가적으로 요구되는 단점이 있다. 블루투스 방식은 와이파이 통신에 비해 통신 범위와 속도가 낮고 통신 대기시간이 비교적 길며 보안성이 취약한 것이 문제점이다. 본 연구에서는 와이파이 통신 기술을 적용한 IEEE 802.11b/g/n 스마트 벽스위치를 개발하였다. 연구의 결과물은 기존 벽스위치에 비해 30%이상 저렴하여 기술 경쟁력뿐만 아니라 가격 경쟁력에서도 시장을 선점할 수 있을 것으로 판단한다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.8B
• /
• pp.954-961
• /
• 2011

To apply Wi-Fi technique to the Broadcast field, we have to study features of IEEE 802.11 Broadcast packet. IEEE 802.11 Broadcast technique cannot guarantee successful packet delivery than IEEE 802.11 Unicast. A promising solution to this problem is the use of FEC(Forward Error Correction) mechanisms. However, the adjustment of the FEC redundancy rate is not a trivial issue due to the dynamic wireless environment. In order to explore the above issues we conducted an experimental study of the packet loss behavior of the IEEE 802.11g protocol. In order to study, we implemented a broadcast test bed. Based on the experimental results, we provide guidelines on wireless lan parameters(packet size, transmission rate(11g), background traffic). From this experimental study, we provide FEC redundancy rate.