http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Block Coding Techniques with Cyclic Delay Diversity for OFDM Systems
두정,회빙,장경희,Du, Ting,Hui, Bing,Chang, Kyung-Hi The Korea Institute of Information and Commucation 2008 韓國通信學會論文誌 Vol.33 No.9a
Cyclic delay diversity (CDD) is considered as a simple approach to exploit the frequency diversity in OFDM system. In this paper, we apply CDD to the conventional STBC/SFBC/STFBC-OFDM transmit diversity schemes for Rayleigh fading channels. We compare the performances of STBC/SFBC/STFBC with and without CDD schemes. Simulation results show that the combination of block coding with CDD works well when using the ITU-R M. 1225 channel for both Pedestrian A (Ped A) channel with the mobility of 3 km/h, and Vehicular A (Veh A) channel with the mobility of 120km/h. For a BER of $10^{-3}$, compared to the conventional block coding schemes, a gain of 2dB, 4dB, and 5dB is obtained under the Ped A channel environment by STBC-OFDM, SFBC-OFDM and STFBC-OFDM with CDD, respectively Under the Veh A channel. gains by the combined schemes are 6dB, 2dB, and 4dB, respectivcly.
VHF 대역 선박 간 애드혹 네트워크에서 실측 해상채널에 기반한 채널 보상과 채널 부호화 기법의 성능분석
전광현(KwangHyun Jeon),회빙(Bing Hui),장경희(KyungHi Chang),김승근(SeungGeun Kim),김시문(SeaMoon Kim),임용곤(YongKon Lim) 한국통신학회 2011 韓國通信學會論文誌 Vol.36 No.3
본 논문에서는 차세대 해상 통신 시스템인 SANET (Ship Ad-hoc NETwork)의 무선 전송 규격 파라미터를 설정하고, VHF 대역의 실측 해상 채널을 분석하여 SANET 채널 모델링을 수행한다. 또한, 프리앰블, guard time, 파일롯을 포함한 단일 및 다중 반송파 시스템을 위한 프레임 구조를 제안하며, 제안된 프레임 구조 하에서 채널보상과 채널 부호화 기법에 의한 SANET 시스템의 BER (Bit Error Rate) 성능을 평가 및 분석한다. 결과로 π/4-DQPSK와 π/8-D8PSK를 적용한 단일 반송파 SANET의 경우, differential 변조방식 채택에 의하여 별도의 채널보상을 하지 않으며, 부호화 이득을 얻을 수 있는 컨볼루션 부호화를 적용하기로 한다. 다중 반송파 SANET의 경우에는 해상환경, 파도에 의한 선박의 움직임 등에 의한 K값의 변화를 고려하여 시스템의 성능을 최대화 하도록 채널 보상 기법과 컨볼루션 부호화를 적용한다. In this paper, the parameters of the RTT (Radio Transmisson Techniques) for SANET (Ship Ad-hoc NETwork), which is considered for the next generation maritime communication systems, are set up. A channel model has been analyzed based on the practical measured maritime wireless channel in VHF (Very-High Frequency) for SANET system. Also, by considering the frame structure including preamble, guard time and pilots for both single and multi-carrier systems, the BER (Bit Error Rate) performances are evaluated and analyzed in the aspects of channel compensation and channel coding techniques. Based on the simulation results, optimal modulation & coding schemes are suggested for SANET. That is, in single-carrier system by using differential modulation schemes, channel compensation is not necessary. However, channel coding is helpful to achieve additional gain. On the other hand, when 16-QAM modulation is employed in multi-carrier system, the implementation of both channel compensation and channel coding techniques show huge performance gain for various of K values, which are related to different maritime environments, and the rolling effects of wave.
Block Coding Techniques with Cyclic Delay Diversity for OFDM Systems
Ting Du(두정),Bing Hui(회빙),KyungHi Chang(장경희) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.9A
Cyclic delay diversity (CDD) is considered as a simple approach to exploit the frequency diversity in OFDM system. In this paper, we apply CDD to the conventional STBC/SFBC/STFBC-OFDM transmit diversity schemes for Rayleigh fading channels. We compare the performances of STBC/SFBC/STFBC with and without CDD schemes. Simulation results show that the combination of block coding with CDD works well when using the ITU-R M. 1225 channel for both Pedestrian A (Ped A) channel with the mobility of 3 ㎞/h, and Vehicular A (Veh A) channel with the mobility of 120 ㎞/h. For a BER of 10-3, compared to the conventional block coding schemes, a gain of 2 ㏈, 4 ㏈, and 5 ㏈ is obtained under the Ped A channel environment by STBC-OFDM, SFBC-OFDM and STFBC-OFDM with CDD, respectively. Under the Veh A channel, gains by the combined schemes are 6 ㏈, 2 ㏈, and 4 ㏈, respectively.