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Kyujin Lee,HyoDuck Seo,Kyesan Lee 중소기업융합학회 2015 중소기업융합학회 국제학술대회논문집 Vol.2 No.1
In this paper, we propose the using Flexible Delivery Channel Selection (FDCS) to improve the QoS for MPEG4/SVC signal in MIMO-OFDM system. When we transmit the SVC signal, it has to consider the priority layer as base layer, and enhanced layer using adaptive channel selection. Especially, base layer has the higher priority, which takes through a good channel. In other hands, the enhanced layer has the lower priority, which takes through a worse channel. Because the priority of both layers are different, which are affected the video quality.
다중경로 레일리 페이딩 채널에서의 부분블록 MC-CDMA의 성능 분석
이규진,이계산 경희-다반 ASIC 설계교육센터 2006 경희-다반 ASIC센터 논문집 Vol.7 No.-
We proposed a new modulation and multiplexing technique named Partial Block MC-CDMA. PB/MC-CDMA might be an efficient system which is more robust against multi-path fading channel. In conventional MC-CDMA system, all users use whole transmitting bandwidth. So it causes performance degradation by interference from all users. Furthermore, capacity of multiple-access is not good compared to proposed system and performance is exponentially degraded because of inter-code interference when uses are increased inner cell. Reversely In PB/MC-CDMA, each block is divided by number of carriers and spreading factor. And users are divided by blocks and in each block, spreading code is reused. By reusing spreading code, proposed scheme accommodate more users than MC-CDMA. Moreover desired signal is interfered not by whole user just as MC-CDMA but by user in block, so it decreases the quantity of interference and increase the performance. Therefore, the perfomuance of the proposed system is better than the conventional MC-CDMA.
PAPR에 의한 영향을 최소화하기 위한 확산코드 선택 부분블록 MC-CDMA
이동준,이계산 경희-다반 ASIC 설계교육센터 2006 경희-다반 ASIC센터 논문집 Vol.7 No.-
Pertial Block MC-CDMA(PB/MC-CDMA) is complemented system of conventional MC-CDMA. Even though MC-CDMA is candidate of 4G communication, it has some limitation. And PB/MC-CDMA is very good system to overcome that limitation and it is shown by paper. Nevertheless, we can not consider PB/MC-CDMA is suitable for 4G communication. Because it has PAPR problem just as other multi-carrier system. In this paper, we proposed the novel peak power reduction technique for PB/MC-CDMA by selecting spreading code. Constant number of spreading code sets are assigned to each user from randomly generated Walsh-Hadamard(WH) code. we called those code as 'pre-assigned code'. After IFFT, PAPR values according to pre-assigned code are calculated to see which spreading code set generates the minimum peak power. Using selected code generated minimum peak power, data are transmitted to minimize the output peak power. By computer simulation, we can certify that BER performance is improved by proposed technique and it represent that proposed method can reduce the error produced by PAPR.