• IE interfaces
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• v.9 no.3
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• pp.64-71
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• 1996

In the survivability and simplicity aspect, SONET Self-healing Ring(SHR) is one of the most important schemes for the high-speed telecommunication networks. Since the ring capacity requirement is defined by the largest STS-1 cross-section in the ring, load balancing is the key issue in the design of SONET SHR. Recently, most of the research on load balancing problem have been concentrated on the SONET single-ring case. However, in certain applications, multiple-ring configuration is necessary because of the geographical limitations or the need for extra bandwidth. In this paper, the load balancing problem for SONET dual-ring is considered by assuming symmetric inter-ring demands. We present a linear programming based formulation of the problem. Initial solution and improvement procedures are presented, which solves the routing and interconnection between the two rings for each demand. Computational experiments are performed on various size of networks with randomly generated demand sets. Results show that the proposed algorithm is excellent in both the solution quality and the computational time requirement. The average error bound of the solutions obtained is 0.26% of the optimum.

• Journal of IKEEE
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• v.20 no.3
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• pp.241-250
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• 2016

AVM(Around View Monitoring) is a function of ADAS(Advanced Driver Assistance Systems), which provides a bird's eye view of the surroundings of a vehicle to the user. AVM systems require large bandwidth since they are composed of four input images and require real-time processing for vehicle-embedded environments. Also, the memory bandwidth requirement increases greatly when the resolution of the input data is higher. In this paper, we propose four basic hardware models of AVM systems. The models are decided by whether or not there is a valid data extraction module and an image processing purpose LUT generation module. We analyze the required bandwidth and hardware resource for each model. For verification of the proposed models, we implemented an AVM system using XC7Z045 FPGA and DDR3 memory for VGA and FHD resolution. All four of the proposed hardware model is executed below 33ms, which shows that it can operate in real-time.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.121-126
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• 2010

A long range UHF RFID tag with a rectangular metallic cavity structure is proposed for various applications with metallic objects. The proposed tag consists of a rectangular metallic cavity structure and a folded dipole antenna which is located on top of the cavity. The tag is designed for Korean UHF RFID band(910~914 MHz) and the bandwidth, which satisfies the -10 dB input reflection coefficient requirement, is approximately 1.3 %(904~916 MHz). Measurement demonstrates that the proposed tag shows long reading range up to 15 m when it is placed on a metallic plate.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.243-245
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• 2009

In recent years, a development of automotive embedded systems called Intelligent Vehicle are used for control and communication with CAN protocol. But as various devices and protocols are developed for Vehicle communication and control, it becomes difficult to manage the systems that contain limitation of bandwidth and various control requirement. To solve these problems, we introduce a research of automotive embedded systems which is considered the automotive real time operating system, automotive communications, and control systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1C
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• pp.65-73
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• 2006

The purpose of this study is to design and analyze the pre-modulation filter with the variable -3dB cutoff frequency and linear phase response for bandlimiting the allocation of radio frequency bandwidth in PCM/FM transmission system. For the implementation of this required filter, the digital FIR filter, DAC and variable 2nd order LPF have been constructed with the filter block which designed and analyzed by each stage in order to satisfy the attenuation characteristic requirement of the analog 7th order bessel filter. The paper also concerned the linear phase properties for the filter block. Especially we have carried out the linear phase simulation with real parts for variable 2nd order LPF and compared this simulation results with the one of the fixed bandwidth 2nd order bessel filter for validating the linear phase requirement.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.9
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• pp.1-6
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• 2010

H.264 video coding standard is widely used due to the high compression rate and quality. H.264 decoders usually have pipeline architecture by a macroblock or a $4{\times}4$ sub-block. The period of the pipeline is usually fixed to guarantee the operation in the worst case which results in many idle cycles and the requirement of high data bandwidth and high performance processing units. We propose adaptive pipeline architecture for H.264 decoders for efficient decoding and lower the requirement of the bandwidth for the memory bus. Parameters and coefficients are delivered using hand-shaking communication through dedicated interconnections and frame pixel data are transferred using AMBA AHB network. The processing time of each block is variable depending on the characteristics of images, and the processing units start to work whenever they are ready. An H.264 decoder is designed and implemented using the proposed architecture to verify the operation using an FPGA.

• Journal of Korea Society of Industrial Information Systems
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• v.13 no.1
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• pp.46-56
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• 2008

Double Patching is a multicasting technique for a VoD system which has been proposed to provide a true VoD service by making clients share a long patching stream as well as a regular stream For subsequent short patching streams, the technique always makes the long patching stream have extra data that will be played back during a double period of a patching window. In this paper, we propose a technique, using the start time of the latest short patching stream, optimizes Double Patching by deleting the useless data included in the long patching stream when the patching window of the long patching stream closes. The mean requirement for the server's bandwidth to provide the true VoD service is used as a performance metric, and the effect of the request inter-arrival time, the size of the client's local buffer and the video length on the mean bandwidth requirement is evaluated. Performance evaluation result shows that the proposed technique optimizes Double Patching in all cases.

• The KIPS Transactions:PartC
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• v.16C no.4
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• pp.487-494
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• 2009

VOD(Video On Demand) that provides streaming service according to the user's requirement in real time, consists of the video streaming server and the client system. Since it is very hard to apply the traditional server-client model that a server communicates with many clients through 1:1 connection to VOD system because it requires very high network bandwidth, many researches have been done to address this problem. Batching technique is one of VOD system based on Multicast that requires very small network bandwidth. However, the batching based VOD system has a limitation that it is very hard to provide VCR(Video Cassette Recorder) ability. In this paper, we propose a technique that reduces the required network bandwidth to provide VCR function by using the characteristic of MPEG, one of international video compression standard. In the proposed technique, a new video stream for VCR function is constructed with I pictures that is able to be decoded independently. The new video stream for VCR function is transmitted with the video stream for normal play together in Batching manner. The performance evaluation result shows that the proposed technique not only reduces the required network bandwidth and memory usage but also decreases the CPU usages.

• The KIPS Transactions:PartB
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• v.15B no.5
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• pp.413-420
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• 2008

Network bandwidth is one of the major factors that impact the cost of a video service. In this paper we propose approaches to reducing the bandwidth requirement for transporting MPEG-4 video traffic over wireless LANs while guaranteeing a required level of quality of service(QoS). To support high quality video playbacks, video frames must be transported to the client prior to their playback times. A real-time transmission scheduling is used for this purpose, which transmits each frame assigned with a priority according to its importance. It addresses the challenge for a scheduling algorithm that efficiently handles the changing workloads of MPEG-4 video traffic. The goal of our research is to maximize the number of frames that are transported within their deadlines while minimizing the tardiness of frames that missed their deadlines. The performance of the proposed method is compared with that of similar service mechanisms through extensive simulation experiments.

• Journal of Ubiquitous Convergence Technology
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• v.2 no.2
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• pp.88-96
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• 2008

IPTV Content delivery systems over wired networks confront scalability problems due to their high network bandwidth requirement for real-time services. Especially, VoD service provides Trick Mode features such as pause, fast forward and similar operations. However, Trick Mode services are delivered by the method of unicast only for controlling of the stream. With a point of views, this paper propose a new real-time multimedia streaming architecture over IP Networks, which tries to achieve bandwidth efficiency and supporting for mass clients better than traditional unicast services. The proposed methods divide the Transport Stream into a series of segments. After that, this divided partial Transport Stream makes multicast streaming periodically. Meanwhile Set-top Box of a client makes a rearrangement orderly by using Presentation Time Stamp field from the served Transport Stream packets. While the current Transport Stream segment is playing, it should be guaranteed that the next segment is downloaded on time. Consequently, the original video content can be played out continuously. The detail introduction of a new real-time multimedia streaming system with analysis and simulation follows as below.