• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.66-71
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• 2011

This paper evaluates the performance and effectiveness of a layered coding scheme for an integrated mobile satellite systems, where the main target services are multimedia broadcasting and multicasting services (MBMS). In this integrated system, the satellite and complementary ground components (CGC) cooperate to provide high quality services. A layered coding scheme is a receiver driven adaptive schemes which adapts to the channel condition at the receiver. In this paper, we introduce a layered turbo coding scheme, and evaluates the performance in various scenarios, and discuss its effectiveness. The demonstrated results in the paper can be utilized in order to design an efficient integrated mobile satellite system, in the future.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1998.06b
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• pp.183-188
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• 1998

This paper describes the concept of object-based coding for future broadcasting environments. Digital broadcasting uses the MPEG2 coding scheme which is regarded as a picture-based coding. An object-based coding scheme is a potential candidate for future broadcasting both for studio and distribution uses, and it offers a higher compression more flexible content handling. This paper also describes key technologies that we have been developing for the object-based coding, e.g., image analysis, object extraction and coding of objects.

• Journal of Broadcast Engineering
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• v.9 no.3
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• pp.225-235
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• 2004

In this paper, we propose a new stereoscopic video coding approach for heterogeneous consumer devices by exploiting the concept of spatio-temporal scalability. The proposed method uses MPEG-2 standard for coding the left or main sequence and an enhanced compatible coding scheme for predicting the P- and B-type of frames of the right or auxiliary sequence. The enhanced compatible coding scheme predicts matching block by interpolating both two forward and backward motion predicted macroblocks and disparity predicted macroblock. To provide flexible stereo video service, we define both a temporally scalable layer and a spatially scalable layer for each eye-view. The experimental results show the efficiency of proposed coding scheme by comparison with already known methods and the advantages of disparity estimation in terms of scalability overhead. According to the experimental results, we expect the proposed functionalities will play a key role in establishing highly flexible stereo video service for ubiquitous computing environment where devices and network connections are heterogeneous.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.190-192
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• 2004

In this paper, we propose a low bit-rate embedded video compression scheme with 3-D block partition coding in the wavelet domain. The proposed video compression scheme includes multi-level 3-dimensional dyadic wavelet decomposition, raster scanning within each subband, formation of block, 3-D partitioning of block, and adaptive arithmetic entropy coding. Although the proposed video compression scheme is quit simple, it produces bit-stream with good features, including SNR scalability from the embedded nature. Experimental results demonstrate that the proposed video compression scheme is quit competitive to other good wavelet-based video coders in the literature.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.501-504
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• 2003

This paper presents a new fractal coding scheme to find more optimal transformation by estimation of the optimal attractor. The conventional fractal coding schemes based on the collage theorem obtain the transformation to minimize the distance between an original image and its collage image. Heavy computation is why the schemes widely adopt the theorem. In other words, the optimal transformation can be obtained after the attractors of all the possible transformations are generated and then compared with an original image. It is clear that this process is not practical. Therefore, we introduce a sub-optimal scheme that provides better transformation than the conventional scheme, relieving the complexity problem in the optimal transformation. In a simple case, the optimal transformation can be obtained considering all the attractors and then our scheme is compared with the optimal. In general cases not to be able to find the optimal, our scheme is also evaluated and compared with the conventional schemes.

• ETRI Journal
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• v.42 no.3
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• pp.341-350
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• 2020

In a wireless sensor network (WSN), the data transmission technique based on the cooperative multiple-input multiple-output (CMIMO) scheme reduces the energy consumption of sensor nodes quite effectively by utilizing the space-time block coding scheme. However, in networks with high node density, the scheme is ineffective due to the high degree of correlated data. Therefore, to enhance the energy efficiency in high node density WSNs, we implemented the distributed source coding (DSC) with the virtual multiple-input multiple-output (MIMO) data transmission technique in the WSNs. The DSC-MIMO first compresses redundant source data using the DSC and then sends it to a virtual MIMO link. The results reveal that, in the DSC-MIMO scheme, energy consumption is lower than that in the CMIMO technique; it is also lower in the DSC single-input single-output (SISO) scheme, compared to that in the SISO technique at various code rates, compression rates, and training overhead factors. The results also indicate that the energy consumption per bit is directly proportional to the velocity and training overhead factor in all the energy saving schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.1
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• pp.22-29
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• 1989

An efficient fixed rate adaptive transform coding is described. Adaptivity is provided by assigning more bits to high ac energy blocks and less bits to low ac energy blocks. Practical and relatively simple adaptation scheme is developed. Overall complexity of our scheme is comparable to the Chen and Smith's scheme. The rate will be adjusted in the same manner as in fixed transform coding. Good performance of the proposed scheme is presented in terms of signal to noise ratio compared with the well known Chen&Smith's scheme. Subjective tests are also presented.

• International journal of advanced smart convergence
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• v.10 no.3
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• pp.17-25
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• 2021

As a new paradigm in non-orthogonal multiple access (NOMA), correlated superposition coding (CSC) has gained an attention in the literature of NOMA, in contrast to standard independent superposition coding (ISC). In the conventional 3-user CSC scheme, it has been reported that the average allocated power can be reduced, owing to an introduced correlation between transmitted signals. Thus, this paper proposes a 3-user cross CSC scheme with purely-imaginary correlation coefficients. First, we derive the achievable data rates of the proposed 3-user cross CSC scheme, for each of the three users. Then, simulations demonstrate that for the proposed 3-user cross CSC scheme, the achievable data rates of the first and second users increase greatly and slightly, respectively, whereas the achievable data rate of the third user decreases little, compared to those of the conventional 3-user CSC scheme. In addition, we also show that the sum rate of the three users of the proposed 3-user cross CSC scheme is much larger than that of the three users of the conventional 3-user CSC scheme. As a result, the proposed 3-user cross CSC scheme could be a solution to the problem of the reduction of the average allocated total power in the conventional 3-user CSC scheme toward the fifth-generation (5G) NOMA mobile networks.

• Journal of Broadcast Engineering
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• v.14 no.5
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• pp.601-615
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• 2009

This paper proposes an efficient depth-map coding method for generating virtual-view images in 3D-Video. Virtual-view images can be generated by the view-interpolation based on the depth-map of the image. A conventional video coding method such as H.264 has been used. However, a conventional video coding method does not consider the image characteristics of the depth-map. Therefore, this paper proposes an adaptive depth-map coding method that can select between the H.264/AVC coding scheme and the proposed gray-coded bit plane-based coding scheme in a unit of block. This improves the coding efficiency of the depth-map data. Simulation results show that the proposed method, in comparison with the H.264/AVC coding scheme, improves the average BD-rate savings by 7.43% and the average BD-PSNR gains by 0.5dB. It also improves the subjective picture quality of synthesized virtual-view images using decoded depth-maps.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.4
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• pp.295-302
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• 2013

In the network coding, throughput can be increased by allowing the transformation of the received data at the intermediate nodes. However, the adversary can obtain more information at the intermediate nodes and make troubles for decoding of transmitted data at the sink nodes by modifying transmitted data at the compromised nodes. In order to resist the adversary activities, various information theoretic or cryptographic secure network coding schemes are proposed. Recently, a secure network coding based on the cryptographic hash function can be used at the random network coding. However, because of the computational resource requirement for cryptographic hash functions, networks with limited computational resources such as sensor nodes have difficulties to use the cryptographic solution. In this paper, we propose a new secure network coding scheme which uses linear transformations and table lookup and safely transmits n-1 packets at the random network coding under the assumption that the adversary can eavesdrop at most n-1 nodes. It is shown that the proposed scheme is an all-or-nothing transform (AONT) and weakly secure network coding in the information theory.