• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1920-1923
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• 2003

This paper presents compression rate improvement for SPIHT algorithm though redundancy bit removing. Proposed SPIHT algorithm uses a method to select of optimized threshold from feature of wavelet transform coefficients and removes sign bit if coefficient of LL area. Experimental results show that the proposed algorithm achieves more improvement bit rate and more fast progressive transmission with low bit rate.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04b
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• pp.903-906
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• 2001

점진적 전송 방식은 낮은 해상도의 영상에서부터 점진적으로 더 높은 해상도의 영상으로 전송이 진행되는 동안 수신측에서 전송된 저해상도의 영상으로 영상의 가치를 판단하여 나머지 부분의 전송을 진행하거나 취소 할 수 있어 제한된 전송 대역을 효과적으로 이용할 수 있다. 본 논문에서는 영상의 점진적 전송을 실현하기 위하여 영상을 비트플랜으로 분리한 후 각 플랜에 대하여 상보 쿼드트리 구조로 재구성한 후 적절한 순서에 따라 데이터를 전송하여 전송 초기단계에 영상의 내용을 대체적으로 파악할 수 있도록 하였다.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.130-133
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• 2003

본 논문에서는 웨이블렛 압축 기반인 SPIHT 알고리즘의 압축효율을 개선시킬 수 있는 방법을 제안한다. 특히 초기치에서 발생될 수 있는 비트소비를 줄임으로써, 낮은 비트율에서 더욱 빠른 점진적인 전송을 구현하였다. 트리구조에 따르는 최적화 된 임계값 설정과 웨이블렛 변환된 계수들의 계수값을 통해 비트율 향상을 얻을 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.11
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• pp.1618-1625
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• 1993

In the transmission of image using the lossless Laplacian pyramid coding, the image quality of the last hierachy is almost same regardless of the bit rate of each hierachy. However, at the higher hierachy with low resolution, it is varied according to bit rate of each hierachy. In this paper, optimum bit allocation to achieve better image at the higher hierachy and minimize the distortion at the last hierachy was proposed. More efficient progressive transmission was shown to be possible by experimental results of higher PSNR and better image quality at the hierachy with low resolution.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.88-88
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• 2002

Satellite Image archiving system requires large storage and long transmission time. A simple and cheap way of overcoming these limitations is to increase the compression ratio. However this requires a feasibility study for accurate applications. Here, a new still image compression standard is being developed, the JPEG2000. It provides lossless and lossy compression, progressive transmission by pixel accuracy and by resolution, region-of-interest coding, user-defined tiling size, random codestream access and processing etc. In this study, we will briefly introduce the JPEG2000 compression standard which provides a new compression technique based on the wavelet technology and offers better compression ratios, and evaluate the compression ratios of JPEG2000 for satellite image by performing various image quality tests. Also, we will compare brief test result using the commercial remote sensing software.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.8 no.1
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• pp.11-17
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• 2008

Typical wireless sensor networks used in structural monitoring are continuous types wherein data transmission is progressive at all time that may include irrelevant and insignificant data and information. Continuous types of wireless monitoring systems often pose problems of handling large-sized data that may deteriorate the performance of the system. The proposed method is to suggest an event-triggered monitoring system that captures and transmits relevant data only. An error signal generated by the Principal Components Analysis (PCA) is utilized as an index for event detection and selective data transmission. With this new monitoring scheme, the remote server is relieved of unwanted data by receiving only relevant information from the wireless sensor networks. The performance of the proposed scheme was verified with simulation studies.

• ETRI Journal
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• v.33 no.2
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• pp.155-162
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• 2011

The scalable extension of the H.264/AVC video coding standard (SVC) demonstrates superb adaptability in video communications. Joint source and channel coding (JSCC) has been shown to be very effective for such scalable video consisting of parts of different significance. In this paper, a new JSCC scheme for SVC transmission over packet loss channels is proposed which performs two-dimensional optimization on the quality layers of each frame in a rate-distortion (R-D) sense as well as on the temporal hierarchical structure of frames under dependency constraints. To compute the end-to-end R-D points of a frame, a novel reduced trellis algorithm is developed with a significant reduction of complexity from the existing Viterbi-based algorithm. The R-D points of frames are sorted under the hierarchical dependency constraints and optimal JSCC solution is obtained in terms of the best R-D performance. Experimental results show that our scheme outperforms the existing scheme of [13] with average quality gains of 0.26 dB and 0.22 dB for progressive and non-progressive modes respectively.

• Journal of Communications and Networks
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• v.2 no.1
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• pp.5-17
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• 2000

cdma2000 offers several enhancement as compared to TIA/EIA-95, although it remains fully compatible with TIA/EIA-95 systems and allows for a smooth migration from one to the other-Major new capability include:1)connectivity to GSM-MAP in addition to IP and IS-41 networks; 2) new layering with new LAC and MAC architectures for improved service multiplexing and QoS management and efficient use of radio resource ;3) new bands and band widths of operation in support of various operator need and constraints, as well as desire for a smooth and progressive migration to cdma 2000; and 4) flexible channel structure in support of multiple services with various QoS and variable transmission rates at up to 1 Mbps per channel and 2 Mbps per user. Given the phenomenal success of wireless services and desire for higher rate wireless services. improved spectrum efficiency was a major design goal in the elaboration of cdma2000. Major capacity enhancing features include; 1) turbo coding for data transmission: 2)fast forward link power control :3) forward link transmit diversity; 4) support of directive antenna transmission techniques; 5) coherent reverse link structure; and 6) enhanced access channel operation. As users increasingly rely on their cell phone at work and at home for voice and data exchange, the stand-by time and operation-time are essential parameters that can influence customer's satisfaction and service utilization. Another major goal of cdma2000 was therefore to enable manufacturers to further optimize power utilization in the terminal. Major battery life enhancing features include; 1) improved reverse link performance (i.e., reduced transmit power per information bit; 2) new common channel structure and operation ;3) quick paging channel operation; 4) reverse link gated transmission ; and 5) new MAC stated for efficient and ubiquitous idle time idle time operation. this article provides additional details on those enhancements. The intent is not to duplicate the detailed cdma2000 radio access network specification, but rather to provide some background on the new features of cdma2000 and on the qualitative improvements as compared to the TIA/EIA-95 based systems. The article is focused on the physical layer structure and associated procedures. It therefore does not cover the MAC, LAC, radio resource management [1], or any other signaling protocols in any detail. We assume some familiarity with the basic CDMA concepts used in TIA/EIA-95.

• Proceedings of the IEEK Conference
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• 2001.06d
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• pp.179-182
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• 2001

This paper has been studied a wavelet based still image transmission over the wireless channel. EZW(Embedded Zerotree Wavelet) is an efficient and scalable wavelet based image coding technique, which provides progressive transfer of signal resulted in multi-resolution representation. It reduces therefore the reduce cost of storage media. Although EZW has many advantages, it is very sensitive on error. Because coding are performed in subband by subband, and it uses arithmetic coding which is a kind of variable length coding. Therefore only 1∼2bit error may degrade quality of the entire image. So study of error localization and recovery are required. This paper investigates the use of reversible variable length codes(RVLC) and data partitioning. RVLC are known to have a superior error recovery property due to their two-way decoding capability and data partitioning is essential to applying RVLC. In this work, we show that appropriate data partitioning length for each SNR(Signal-to-Noise Power Ratio) and error localization in wireless channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2C
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• pp.324-332
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• 2004

In image communications related to web browsing, image database, and telemedicine, image data processing on the region of interest (ROI) for providing the primary information is needed in the view of saying search time and bandwidth. In this paper, an enhanced algorithm for processing image data that involves multiple ROIs is presented in order to increase PSNR vs. compression ratio performance above the previous JPEG2000 Part1 Maxshift method. Since the wavelet transform enables us to a progressive transmission mechanism, Multiple-ROI coding is possible to compress, transmit, and reconstruct the image data with a better quality than those of non-ROI method while the required transmission bandwidth is kept relatively low.