• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.3
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• pp.324-340
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• 2010

Video streaming service over wireless networks is a challenging task because of the changes in the wireless channel conditions that can occur due to interference, fading, and station mobility. To provide an efficient wireless video streaming service, the rate adaptation scheme should improve wireless node performance and channel utilization. Moreover, the quality adaptation scheme should be considered at the streaming application. To meet these requirements, we propose a new cross-layer design for video streaming over wireless networks. This design includes the rate and quality adaptation schemes. The rate adaptation scheme selects the optimal transmission mode and resolves the performance anomaly problem. Based on performance improvement by the proposed rate adaptation scheme, our quality adaptation scheme improves the quality of video streaming. Through performance evaluations, we prove that our cross-layer design improves the wireless channel utilization and the quality of video streaming.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.69-84
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• 2020

Natural shoreline repeats its re-treatment and advance in response to the endlessly varying sea-conditions, and once severely eroded under stormy weather conditions, natural beaches are gradually recovered via a boundary layer streaming when swells are prevailing after storms cease. Our understanding of the boundary layer streaming over surf-zone often falls short despite its great engineering value, and here it should be noted that the most sediments available along the shore are supplied over the surf-zone. In this rationale, numerical simulation was implemented to investigate the hydraulic characteristics of boundary layer streaming over the surf zone in this study. In doing so, comprehensive numerical models made of Spatially filtered Navier-Stokes Eq., LES (Large Eddy Simulation), Dynamic Smagorinsky turbulence closure were used, and the effects of turbulence closure such as Dynamic Smagorinsky in LES and k-ε on the numerically simulated flow field were also investigated. Numerical results show that due to the intrinsic limits of k-ε turbulence model, numerically simulated flow velocity near the bottom based on k-ε model and wall function are over-predicted than the one using Dynamic Smagorinsky in LES. It is also shown that flow velocities near the bottom are faster than the one above the bottom which are relatively free from the presence of the bottom, complying the typical boundary layer streaming by Longuet-Higgins (1957), the spatial scope where boundary layer streaming are occurring is extended well into the surf zone as incoming waves are getting longer. These tendencies are plausible considering that it is the bottom friction that triggers a boundary layer streaming, and longer waves start to feel the bottom much faster than shorter waves.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.352-354
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• 2005

As further Studies on 4th generation mobile telecommunication are progressed, the importance of a Cross-Layer is being increased. However, it has focused on coordination model only between MAC layer and PHY layer. It is necessary to expand into II' layer and upper layers. In this paper, we introduce a Cross-layer optimization which can be used to transmit video data with effect by managing resources among layers. It can gives further more adaptive method to solve QoS model problem than single layer.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.98-100
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• 2005

This paper, proposes concept of personal robot middleware core also called streaming layer. Based on openness and portability, the streaming layer is proposed in order to meet requirements of different kinds of applications. The streaming layer architecture provides effective management of data flows and allows integration of different systems with ease regardless software of hardware platform. With extensibility support additional features can be build in without affect to performance. Therefore, heterogeneous network support, real-time communications, embedded boards support can be easily achieved. In order to achieve high performance together with portability into different platforms, the most functions has to be implemented in C language, while critical parts, such as scheduling, priority assignment has to be made using native functions of tested platforms.

• Journal of Digital Convergence
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• v.11 no.5
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• pp.313-318
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• 2013

QoS in wireless multimedia sensor networks is an important issue to enhance streaming media service. This paper proposes a new 2-layer based QoS evaluation scheme for enhancing the streaming media QoS of wireless multimedia sensor networks. The proposed scheme performs the fuzzy relevance to control the streaming between application layer and network layer, and it performs 2-layer mapping process to enhance the transmission reliability and throughput. The simulation results show that the proposed scheme achieves improved performance in packet control ratio, transmission reliability, and delay overhead ratio compared with those of other existing schemes.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1936-1939
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• 2004

This paper proposes streaming layer for personal robot's middleware. Under assumption that robot has open architecture, i.e. consists of modules created by different vendors and intercommunication between these modules is necessary, we have to consider that there are many different network interfaces. To make communication between modules possible it is necessary to develop new type of middleware. Such middleware has to support different platforms, i.e. OS, network interface, hardware, etc. In addition, it is necessary to implement effective interface between network and application in order to manage inter application communications and use network resources more effectively. Streaming layer is such interface that implements necessary functionality together with simplicity and portability. Streaming layer provides high level of abstraction and makes communication between distributed applications transparent as if are located in same module. With possibility of extension by user defined application interfaces it is suitable for distributed environments, i.e. module based architecture including small-embedded systems like as DSP board. To verify the proposed streaming layer structure it is implemented using C and tested.

• Journal of Korea Multimedia Society
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• v.18 no.7
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• pp.853-863
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• 2015

In this paper, we proposed cross-layered approach of video codec and communication system for the efficient video streaming service. Conventional video streaming is served by divided system which consist of video codec layer and communication layer. Its disintegration causes the limitation of the performance of video streaming service. With the cross-layered design, each layer could share the information and the service is able to enhance the performance. And we proposed the selective retransmission method in communication system based on the cross-layered system that reflect the information of encoded video data. Selective retransmission method which consider the characteristics of video data improves the performance of video streaming services. We verified the proposed method with raw format full HD test sequence with H.264/AVC codec and MATLAB simulation. The simulation results show that the proposed method improves about 10% PSNR performance.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.55-68
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• 2020

In order to investigate the hydraulic characteristics of a boundary layer streaming over the beach cusps appeared in swells prevailing mild seas, we numerically simulated the shoaling process of Edge waves over the beach cusp. Synchronous Edge waves known to sustain the beach cusps could successfully be duplicated by generating two obliquely colliding Edge waves in front of beach cusps. The amplitude A_B and length L_B of Beach Cusp were elected to be 1.25 m and 18 m, respectively based on the measured data along the Mang-Bang beach. Numerical results show that boundary layer streaming was formed at every phase of shoaling process without exception, and the maximum boundary layer streaming was observed to occur at the crest of sand bar. In RUN 1 where the shortest waves were deployed, the maximum boundary layer streaming was observed to be around 0.32 m/s, which far exceeds the amplitude of free stream by two times. It is also noted that the maximum boundary layer streaming mentioned above greatly differs from the analytical solution by Longuet-Higgins (1957) based on wave Reynolds stress. In doing so, we also identify the recovery procedure of natural beaches in swells prevailing mild seas, which can be summarized such as: as the infra-gravity waves formed in swells by the resonance wave-wave interaction arrives near the breaking line, the sediments ascending near the free surface by the Phase II waves orbital motion were carried toward the pinnacle of foreshore by the shoreward flow commenced at the steep front of breaking waves, and were deposited near the pinnacle of foreshore due to the infiltration.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.95-98
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• 2003

To provide high-quality media streaming service over the best-effort Internet, an efficient streaming system with a network-adaptive transport is essential. By adopting FEC-based adaptive transport and by matching it to the priority of media packets, in this paper, an enhanced MPEG-4 streaming system is implemented. The implemented adaptive transport can complement the existing MPEG-4 streaming server with components such as elementary stream provider, sync layer and DMIF layer. Sync layer packets of each MPEG-4 elementary stream are prioritized and then selectively dropped at the sender to match the currently available bandwidth. Also, with the proposed adaptive transport module, the level of FEC protection is dynamically adjusted based on the underlying network condition. With preliminary verification over the emulated network testbed, it is shown that the proposed implementation can mitigate the impact of network fluctuation and thus improve the quality of streaming.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3775-3788
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• 2014

With the increasing number of the wireless and mobile networks, the way that people use the Internet has changed substantively. Wireless multimedia services, such as wireless video streaming, mobile video game, and mobile voice over IP, will become the main applications of the future wireless Internet. To accommodate the growing volume of wireless data traffic and multimedia services, cognitive radio (CR) and Information-Centric Network (ICN) have been proposed to maximize the utilization of wireless spectrum and improve the network performance. Although CR and ICN have high potential significance for the future wireless Internet, few studies have been conducted on collaborative operations of CR and ICN. Due to the lack of infrastructure support in multi-hop ad hoc CR networks, the problem is more challenging for video streaming services. In this paper, we propose a Cross-layer Video Streaming Mechanism (CLISM) for Cognitive Radio Ad Hoc Information Centric Networks (CRAH-ICNs). The CLISM included two distributed schemes which are designed for the forwarding nodes and receiving nodes in CRAH-ICNs. With the cross-layer approach, the CLISM is able to self-adapt the variation of the link conditions without the central network controller. Experimental results demonstrate that the proposed CLISM efficiently adjust video transmission policy under various network conditions.