• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.7A
• /
• pp.755-761
• /
• 2007

In this paper the uplink single carrier scheme is proposed for wireless Internet application and its performance is evaluated in terms of PAPR (peak to average power ratio) and ABR (achievable bit rate) compared with the uplink OFDM scheme. There exist constraints regarding the signal amplification because the non-linear amplifier should be exploited instead of the linear amplifier due to its high cost of linear amplifier and power inefficiency at the WiBro terminal. Therefore characteristics in the uplink scheme design are discussed in order to maximize ABR and relieve the requirements for the amplifier specifications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2008.05a
• /
• pp.921-924
• /
• 2008

Recently, ultra-wideband(UWB) technology based on the transmission of short duration pulses has gained much interest for its application to wireless communications. Various wireless communication and wireless broadcast will require more efficient use of frequency. Cognitive radio technology is an intelligent technology which can sense the spectrum environment and adaptively adjust the parameters for wireless transmission. In this paper, by using Cognitive UWB, the spectrum efficiency of the transmission channels is largely improved, and the interference between the other systems can be effectively avoided.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.6A
• /
• pp.894-904
• /
• 1999

In this paper, a synchronized stream cryptosystem for secure communication in radio channel is designed and its security level is analyzed. The main parts of the proposed cryptosystem consist of synchronization pattern generator, session key generator, and key stream generator. The system performance is evaluated by analyzing the security level depending on the randomness, period, linear complexity, and correlation immunity. Experimental results with image data signal in the 10-1 and 10-2 channel error environment demonstrate the proper operation of the implemented crypto system.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.2 no.1 s.2
• /
• pp.93-100
• /
• 2003

In this farer, An ADSRC(Advanced Dedicated Short Range Communication) packet communication system developed by ETRI is introduced. The ADSRC system has been developed to provide high-speed, short-range wireless racket communication in roadside environment for mobile office services. The requirements of the ADSRC system for mobile office services and the system design specification to meet them with regard to mobile of nce environment are discussed. The ADSRC packet communication systems consist of the MAC(Medium Access Control) Processor block the OFDM() modem block and the RF block. The MAC processor block handles medium access control. The OFDM modem transmits data packets at up to 24Mbps adaptively and recovers the data from RF block. The ADSRC packet communication system architecture is described.

• The Journal of the Korea Contents Association
• /
• v.4 no.4
• /
• pp.71-78
• /
• 2004

Dedicated Short Range Communications(DSRC) as a prominent communications candidate for Intelligent Transportation Systems(ITS) have been developed to support ITS applications such as value-added information service, e-commerce, electronic toll payment, etc. These various applications associated with electronic payment through unsecure communication channel of DSRC suffer from security threats. To ensure secure payment, we have adopted appropriate cryptographic mechanisms including encipherment, authentication exchange and digital signature. The cryptographic mechanisms require to use cryptographic keys established between two communication entities. In this paper, we propose a secure electronic payment system which is designed to have some functions for strong authentication, encryption, key agreement, etc. Especially, we adopt domestic developed cryptographic algorithms such as EC-KCDSA and SEED for digital signature and block cipher, respectively. We can show those mechanisms are appropriate for the secure electronic payment system for ITS services under the DSRC wireless environment in aspects of constrained computational resource use and processing speed.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.9B
• /
• pp.1381-1389
• /
• 2010

The smart grid technology is expected to significantly improve energy efficiency by dynamic power supply. One of its application is the Vehicle-to-Grid(V2G) that utilizes an electric vehicle's battery as a household storage battery. Meanwhile, a lot of researches are recently investigated in the area of wireless energy transfer technology because of its convenience and safety in charging a battery. With the wireless energy transfer infrastructure a wireless magnetic induction communication technique can help the dynamic power supply of the smart grid more efficient. In this paper, we propose a wireless magnetic induction communication sion cowhich includes data transmission and location-aware functions. We expect the sion cohelp the smart grid to control power supply more efficiently. We also developed its test-bed and evaluated the performance.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.23 no.3
• /
• pp.326-332
• /
• 2019

Recently, the deep learning technology has gained lots of attention which leads to its application to various fields. Especially, there are recent attempts to overcome the limit of wireless communications systems through the use of the deep learning. In this paper, we have verified the performance of deep learning based transmit power control scheme. Unlike previous transmit power control schemes where the optimal transmit power is derived by solving the optimization problem explicitly, in the deep learning based transmit power control, the general solver for the optimization problem is derived through the deep neural network (DNN). Especially, by using the spectral efficiency as the loss function of DNN, the training can be performed without needing labels. Through simulation based on Tensorflow, we confirm that the transmit power control based on deep learning can achieve the optimal performance while reducing the computational complexity by 1/200.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.9
• /
• pp.1633-1637
• /
• 2008

A protocol is proposed to control the rate of each subcarrier in OFDM-based wireless network systems. The proposed protocol adds an OFDM symbol in CTS frame defined in IEEE 802.11 standard. A receiver determines the rate of its subcarrier after it receives the RTS frame. The determined rate is added to OFDM symbol in CTS frame. In order to synchronize the rate information between the sender and the receiver, error recovery process is proposed. The performance improvement of the proposed method is shown by numerical results.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.10
• /
• pp.2239-2244
• /
• 2013

Industrial machines have constraints on movement due to its wire for power supply. Recently, the research on wireless power supply for industrial machine which is required to move freely is receiving a lot of attention. In this paper, we suggest a magnetic induction system which can charge a equipment's battery with wireless at a close range. The system was designed to operate at 13.56 MHz and a distance of 20~30 mm between the transmitting and the receiving power module. From experiment, it was found that it takes about 135 minutes for charging the battery with about 15 V using the proposed system.

• 한국ITS학회지
• /
• v.1 no.1
• /
• pp.28-32
• /
• 2003

가속화된 자동차의 대중화로 차량증가에 따른 도로의 확장 및 신설에만 의존해오던 기존의 틀을 벗어나 첨단정보통신기술을 이용하여 도로교통 정보를 신속히 수집하고 교통정보 이용자에게 실시간으로 분배함으로써 효율적인 교통관리가 가능한 지능형 교통시스템의 도입이 시작하였다. 최근, 공중 무선 통신망과 달리 도로상에서 고속 주행중인 차량을 대상으로 하여 도로변에 비교적 간단한 기지국 시스탬을 설치하고 저가의 통신단말기로서 사용자에게 값싼 서비스를 제공할 수 있는 장점을 가지고 있을 뿐 만 아니라 적은 비용으로 교통정보수집 및 제공뿐만 아니라, 인터넷 접속, e-mail 송수신 디지털 음성 및 비디오 파일 다운로드가 가능한 텔레메틱스 서비스가 급속도로 가속화하고 있다. 본 고에서는 텔레메틱스 서비스가 차량과 접목된 이동 무선 데이터 통신 기술과 함께 발전 될 전망으로 요소기술을 살펴보았다.