• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.55-58
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• 2007

An adaptive subcarrier allocation scheme based on comparative superiority of opportunity cost between groups is proposed for the enhancement of system capacity and its simple implementation at the base station of a multiuser OFDM system. The proposed algorithm is similar to the blockwise or the decentralized subcarrier allocation algorithm proposed by Xiaowen et al and Alen et al, respectively. In the proposed algorithm, however, all subcarriers are grouped according to the coherence bandwidth and the comparative superiority concept, which swaps the groups between users if the system capacity is increased, is adopted for the enhancement of system capacity. In addition, the proposed algorithm provides a simple solution for the conflict problem among users by reallocating only the conflicted groups and unassigned groups instead of reallocating entire groups. Simulation results demonstrate that the proposed algorithm increases the system capacity effectively over a static, an adaptive blockwise, and a decentralized subcarrier allocation algorithms.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.406-408
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• 2005

A passive Optical Network (PON) is famous for the most cost-efficient solution among the optical networks. This is because there is no active device between a central office and subscribers. A wavelength division multiplexing (WDM) offers each subscriber to feel unlimited bandwidth. A WDM-PON, however, has a cost problem that WDM-PON is used commercially. To solve this trouble, it is surveyed that a Sub-Carrier Multiplexing (SCM) used in a WDM-PON increases the number of subscribers. The performance of WDM/SCM-PON varies with various noises. The several FEC Codes can reduce the effects of noise and improve the performance of the system. Thus, Choosing a suitable FEC code is important work. This paper describes that a Reed-Solomon (RS) code is the most suitable code for WDM/SCM-PON at the object of 100 Mbps and $10^{-9}$ BER

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.6
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• pp.1147-1165
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• 2011

We present a simple and cost effective rate control scheme for streaming video over a wireless channel by using the information of mobile devices' buffer level. To prevent buffer fullness and emptiness at receivers, the server should be able to adjust sending rate according to receivers' buffer status. We propose methods to adjust sending rate based on the buffer level and discrete derivative of the buffer occupancy. To be compatible with existing network protocols, we provide methods to adjust sending rate by changing the inter-packet delay (IPD) at the server side. At every round-trip time, adjustments of sending rate are made in order to achieve responsiveness to sudden changes of buffer availabilities. A series of simulations and the prototype system showed that the proposed methods did not cause buffer overflows and it can maintain smoother rate control and react to bandwidth changes promptly.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.45-48
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• 2003

We can easily buy network system for high performance micro-processor, progress computer architecture is caused of high bandwidth and low delay time. Coupling PC-based commodity technology with distributed computing methodologies provides an important advance in the development of single-user dedicated systems. Lately Network is joined PC or workstation by computers of high performance and low cost. Than it make intensive that Cluster system is resembled supercomputer. Unix, Linux, BSD, NT(Windows series) can use Cluster system OS(operating system). I'm chosen linux gain low cost, high performance and open technical documentation. This paper is benchmark performance of Beowulf clustering by UltraSPARC-1K(64bit-RISC processor). Benchmark tools use MPI(Message Passing Interface) and NetPIPE. Beowulf is a class of experimental parallel workstations developed to evaluate and characterize the design space of this new operating point in price-performance.

• ETRI Journal
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• v.37 no.4
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• pp.685-695
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• 2015

This paper proposes a novel video delivery scheme that reduces the bandwidth consumption cost from a video server to terminals in Long-Term Evolution networks. This proposed scheme combines optimized hybrid multicast with a segment-based caching strategy for use in environments where the maximum number of multicast channels is limited. The optimized hybrid multicast, allocation of multicast channels, and cache allocation are determined on the basis of a video's request rate, the related video's length, and the variable cost per unit size of a segment belonging to the related video. Performance evaluation results show that the proposed scheme reduces a video's delivery costs. This work is applicable to on-demand TV services that feature asynchronous video content requests.

• ETRI Journal
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• v.41 no.2
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• pp.262-269
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• 2019

This paper introduces a low-cost, high-performance mmWave antenna array module at 77 GHz. Conventional waveguide transitions have been replaced by 3D CPW-microstrip transitions which are much simpler to realize. They are compatible with low-cost substrate fabrication processes, allowing easy integration of ICs in 3D multi-chip modules. An antenna array is designed and implemented using multilayer coupled-fed patch antenna technology. The proposed $16{\times}16$ array antenna has a fractional bandwidth of 8.4% (6.5 GHz) and a 23.6-dBi realized gain at 77 GHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3468-3473
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• 2013

Conditions that overlay multicast tree must satisfy for the real-time application system of a video-conference, an internet broadcasting is two things. First, the degree of nodes in a tree must be proper value. Second, the diameter of the multicast tree, distance between longest two users should be short. If the path between two users in the tree is long, the delay time in data transmission between two users great. So, it is not suitable to the application system such as video-conferences. In this paper, the cost of the dijkstra algorithm calculate with proposed score-function through checking the extra bandwidth, the delay and the requested bandwidth. It is composed the tree through the dijkstra algorithm.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.37 no.6
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• pp.1-9
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• 2000

This paper presents a Cluster Oriented Multistage Interconnection Network called COMR. COMR can be constructed suitable for the parallel application with localized communication by providing the shortcut path inside the processor-memory cluster which has frequent data communication. We evaluate the performance of COMR with respect to probability of acceptance, bandwidth, cost-effectiveness and average distance under varying degrees of localized communication. According to the result of analysis for performance evaluation, COMR shows higher performance than the regular MINs of the same network size in the highly localized communication. In the worst case, the diameter of an N$\times$N COMR is only n+1 which has only one stage more as compared the MIN with the same network size. Therefore COMR can be used as an attractive interconnection network for parallel applications with not only the localized communication distribution but also the uniform distribution in shared-memory multiprocessor system.

• Asia Pacific Journal of Business Review
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• v.1 no.1
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• pp.67-88
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• 2016

This study aims to help address concerns about the growing demand of wider bandwidth Internet connection in the Philippines. Using articles and research of international organizations and content from official websites of the Philippine government, this paper has carefully examined the slow Internet connectivity and the high cost that the end-users pay for it. This paper suggests that this inefficiency hampers the motivation of users to innovate in a way that could contribute to inclusive growth and the development of an inclusive information society. Through a comparison of the current global ICT situation with the current situation in the Philippines, this paper shows that the country's Internet infrastructure lags behind among those of contemporary developing countries in Asia, particularly in terms of Internet connectivity. In 2015, Thailand had an average Internet speed of 7.4 Mbps, Sri Lanka 7.4, and Malaysia 4.3. Meanwhile, the Philippines had a meager average Internet speed of 2.8 Mbps, placing the country at 104 among 160 countries, with developed countries in Asia such as South Korea (23.6 Mbps) and Singapore (12.9 Mbps) ranking 1 and 12, respectively. Findings show that the lack of competition in the Internet connectivity market, among other reasons, is at the root of the dilemma of slow and costly Internet connection. Assessing the accomplishments of the Republic of Korea and other broadband-leading countries has provided practical insights and recommendations that can promote competitiveness. Furthermore, related literature argues how ISP practices may affect Internet speed and cost. This study offers an approach in improving Internet connectivity in the Philippines by bridging the gap between the Internet infrastructure market and government policies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4B
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• pp.183-190
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• 2007

The cdma2000 mobile network covers a wide area but its characteristics are high cost and low bandwidth. On the other hand, WLAN covers a small area like a hot spot area but its characteristics are large bandwidth and low cost. Thus we can provide efficient services when we employ an integration network between WLAN and cdma2000 mobile networks. In this paper, we propose an integration scheme between WLAN and cdma2000 mobile networks. In addition, we design and implement the dual mode terminal which receives seamless data services in the integrated network. The proposed dual mode terminal manages connections by monitoring the signal strength of WLAN and selecting a proper network. We validate the functions through the implementation of VOD and show the effectiveness through the performance measurement.