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무선 네트워크에서 Snoop 프로토콜을 적용한 TCP성능 향상
문일영 한국기술교육대학교 2006 論文集 Vol.12 No.1
TCP performs at an acceptable efficiency over the traditional wired networks where packet losses are usually caused by network congestion. However, in networks with wireless links in addition to wired segments this assumption would be insufficient, as the high wireless bit error rate could become the dominant cause of packet loss and thus TCP performs sub-optimum under these new conditions. As the main reason of this poor performance for TCP we may raise the fact that TCP cannot distinguish between packet losses due to wireless errors from those due to congestion. In this paper, based on the existing Snoop protocol, we evaluate performance improvement of TCP at the base station and throughput performance of a new protocol named AT(Adaptive-Timer) Snoop Protocol at the base station with multiple mobile host. Simulation results show that the proposed scheme improves the throughput performance of TCP in wireless environment significantly.
문일영 한국기술교육대학교 2006 論文集 Vol.13 No.1
In this paper, robust digital watermarking scheme to transmit effectively the compressed medical image in mobile Internet. First, we compressed image using fixed length code (FLC) which can be classified by significance. Second, we add the error correction code to watermark data for robust transmission. Third, in order to maintain image quality, we embed with watermark bits in the least significant bits of the host image. And we transmit the watermarked image on a Orthogonal Frequency Division Multiplexing/16 Quadrature Amplitude Modulation (OFDM/16QAM) and confirm its performance by the computer simulation. Last, we compare the Peak Signal-to-Noise Ratio (PSNR) performance of watermarked image and the Mean Square Error (MSE) performance of watermarking data which is corrected or is not corrected.