• Journal of Communications and Networks
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• 제9권3호
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• pp.229-235
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• 2007

This paper analyzes the performance of a Bluetooth piconet in error-prone environments. A statistical characterization of a waiting time, an end-to-end delay, and a goodput are derived analytically in terms of the arrival rates, the number of slaves, and the packet error rate (PER). For simplicity, half-symmetric piconet is assumed in this analysis. Both exhaustive and limited scheduling are considered. The analytic results are validated by simulations.

• ETRI Journal
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• 제29권1호
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• pp.18-26
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• 2007

This paper presents an improved redundant picture coding method that efficiently enhances the error resiliency of H.264. The proposed method applies polyphase downsampling to residual blocks obtained from inter prediction and selectively encodes the rearranged residual blocks in the redundant picture coding process. Moreover, a spatial-temporal sample construction method is developed for the redundant coded picture, which further improves the reconstructed picture quality in error prone environments. Simulations based on JM11.0 were run to verify the proposed method on different test sequences in various error prone environments with average packet loss rates of 3%, 5%, 10%, and 20%. Results of the simulations show that the presented method significantly improves the robustness of H.264 to packet loss by 1.6 dB PSNR on average over the conventional redundant picture coding method.

• 스마트미디어저널
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• 제6권2호
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• pp.9-14
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• 2017

무선 환경에서의 패킷 손실은 비디오 통신과정에서 심각한 비디오 품질 저하를 초래한다. 이 논문에서는 블록의 신뢰도와 블록 경계면 매칭을 기반으로 한 비디오 에러 은닉 기술에 대해서 제안한다. 손실된 블록의 모션 정보를 참조 프레임의 동일한 위치에 존재하는 블록의 모션 정보를 복사하여 사용함으로써 임시로 손실된 블록의 잡음을 은닉하고, 블록의 신뢰도를 기준으로 블록의 신뢰도가 낮은 경우에는 추가적으로 블록의 경계면 매칭을 이용하여 모션 벡터를 재탐색하여 잡음 은닉에 대한 정확도를 높이도록 하였다. 실험을 통해서 제안된 기법이 다양한 패킷 손실 환경에서 우수한 에러 은닉 성능을 보임을 확인하였다.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권8호
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• pp.510-516
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• 2005

Rapid advances in telecommunication make emergency telemedicine possible that specialist offers medical care to an emergency case in moving vehicle. Although there were many telemedicine projects delivering the image or video of patient over several wireless networks, none of them considered effective solutions for optimizing video transmission over error-prone environments, such like wireless links. To alleviate the effect of channel errors on compressed video bit-stream, this paper analyzed the error resilient features of MPEG-4 standard and measured the quality of transmitted MPEG-4 encoded video over commercially available CDMA2000 1xEV-DO networks, transmitting different IP packet sizes and RM positions. we propose an error resilient transmission methods for emergency telemedicine over real 3G network.

• ETRI Journal
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• 제40권2호
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• pp.266-274
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• 2018

In error-prone wireless environments, it is difficult to realize video coding systems that are robust to various types of data loss. In this paper, a novel motion-vector refinement approach is presented for video error concealment. A traditional boundary-matching approach is exploited to reduce blocky effects along the block boundary. More specifically, a downhill simplex approach is combined with a boundary-matching approach to fine-tune the motion vectors, reducing the blocky effects along the prediction unit block boundary, and minimizing the computational cost. Extensive simulations are performed, and the results obtained verify the robustness and effectiveness of the proposed approach.

• 한국정보시스템학회지:정보시스템연구
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• 제14권3호
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• pp.48-52
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• 2005

The Mobile agent-based distributed systems become obtaining significant popularity as a potential vehicle to allow software components to be executed on heterogeneous environments despite mobility of users and computations. However, as these systems generally force mobile agents to use only common functionalities provided in every execution environment, the agents may not access environment-specific resources. In this paper, we propose a new framework using Aspect Oriented Programming technique to accommodate a variety of static resources as well as dynamic ones whose amount is continually changed at runtime even in the same execution environment. Unlike previous works, this framework divides roles of software developers into three groups to relieve application programmers from the complex and error prone parts of implementing dynamic adaptation and allowing each developer to only concentrate on his own part. Also, the framework enables policy decision makers to apply various adaptation policies to dynamically changing environments for adjusting mobile agents to the change of their resources.

• 대한전자공학회논문지SP
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• 제39권6호
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• pp.591-601
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• 2002

동영상 압축에서 움직임 보상은 뛰어난 압축 효율을 보이는 반면에 어느 한 시점에서 오류가 발생할 경우 그 시점 이후로 계속해서 오류가 확산된다는 단점이 있다. 인트라 업데이트 방법은 이러한 오류의 확산을 차단하는 방법이다. 그러나 인트라 업데이트 방법은 압축의 효율을 떨어뜨린다는 단점이 있다. 본 논문에서는 오류의 영향과 비트율 제어를 함께 고려하여 인트라 업데이트를 할 수 있는 방법을 제안한다. 제안된 방법은 비트율과 왜곡의 값을 추정하고 라그랑지안 최적화를 통해 부호화 모드와 양자화 파라메터를 선택하는 방법으로 MPEG-4 코덱에 적용하여 실험하였다. 실험 결과는 제안된 방법이 기존의 방법보다 패킷 손실과 같은 오류 환경에서 더 좋은 화질을 나타내는 것을 보여준다.

• Journal of information and communication convergence engineering
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• 제14권4호
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• pp.240-245
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• 2016

Scalable video streaming over wireless networks has many challenges. The most significant challenge is related to packet loss. To overcome this problem, in this paper, we propose an unequal loss protection (ULP) method using a new forward error correction (FEC) mechanism for robust scalable video streaming over wireless networks. For an efficient FEC assignment considering video quality, we first introduce a simple and efficient performance metric, the layer-based recovery rate (LRR), for quantifying the unequal error propagation effects of the temporal and quality layers on the basis of packet losses. LRR is based on the unequal importance in both the temporal and the quality layers of a hierarchical scalable video coding structure. Then, the proposed ULP-LRR method assigns an appropriate number of FEC packets on the basis of the LRR to protect the video layers against packet lossy network environments. Compared with conventional ULP algorithms, the proposed ULP-LRR algorithm demonstrates a higher performance for various error-prone wireless channel statuses.

• The Journal of the Acoustical Society of Korea
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• 제28권2E호
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• pp.35-42
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• 2009

In this paper, we present criteria of objective measurement of speech quality to provide the mobile-VoIP services efficiently over wireless mobile internet. The mobile-VoIP service, which is based on mobility and is error-prone compared to conventional VoIP over wired network, is about to be launched, but there have not been adequate quality indexes and the Quality of Service (QoS) standards for evaluating speech quality of Mobile-VoIP. In addition, there are many factors influencing on the speech quality in packet network of which packet loss contribute directly to the overall voice communication quality. For this reason, we adopt the Gilbert-Elliot Channel Model for modeling packet network based on IP and assess the voice quality through the objective speech method of ITU-T P. 862 PESQ and ITU-T P. 862.1 MOS-LQO under various packet loss rates in the transmission channel environments. Our simulation results address the specific criteria and QoS for the mobile-VoIP services in terms of the various packet loss environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1141-1163
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• 2019

In an effort to minimize operational expenses and supply users with more scalable services, distributed applications are actually going towards the Cloud. These applications, sent out over multiple environments and machines, are composed by inter-connecting independently developed services and components. The implementation of such programs on the Cloud is difficult and generally carried out either by hand or perhaps by composing personalized scripts. This is extremely error prone plus it has been found that misconfiguration may be the root of huge mistakes. We introduce AutoBot, a flexible platform for modeling, installing and (re)configuring complex distributed cloud-based applications which evolve dynamically in time. AutoBot includes three modules: A simple and new model describing the configuration properties and interdependencies of components; a dynamic protocol for the deployment and configuration ensuring appropriate resolution of these interdependencies; a runtime system that guarantee the proper configuration of the program on many virtual machines and, if necessary, the reconfiguration of the deployed system. This reduces the manual application deployment process that is monotonous and prone to errors. Some validation experiments were conducted on AutoBot in order to ensure that the proposed system works as expected. We also discuss the opportunity of reusing the platform in the transition of applications from Cloud to Fog computing.