• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권8호
• /
• pp.3068-3078
• /
• 2015

Although the massive MIMO system supports a high throughput, it requires a lot of channel information for channel compensation. For the reduction of overhead, the massive MIMO system generally uses TDD as duplexing scheme. Therefore, the massive MIMO system is sensitive to rapidly changing fast fading in according to time. For the improvement of reduced SINR by fast fading, the adaptive power control is proposed. Unlike the conventional scheme, the proposed scheme considers mobility of device for adaptive power control. The simulation of the proposed scheme is performed with consideration for mobility of device. The result of the simulation shows that the proposed scheme improves SINR. Since SINR is decreased in according to the number of device in the network by unit of cell, each base station can accommodate more devices by the proposed scheme. Also, because the massive MIMO system with high SINR can use high order modulation scheme, it can support higher throughput.

• 한국통신학회논문지
• /
• 제32권1A호
• /
• pp.34-43
• /
• 2007

In the IEEE 802.15.3 Medium Access Control (MAC) protocol, Simultaneously Operating Piconets (SOPs) are linked by the parent/child (P/C) or parent/neighbor (P/N) configuration, which work on a Time Division Multiple Access (TDMA) basis. This provides interference mitigation but the overall throughput is limited because the SOPs share the channel time exclusively. The protocol is not efficient for SOPs if we focus on the combination of interference mitigation and high throughput maintenance. In this paper Public Channel Time Allocation (Public CTA) is proposed, which is able to greatly reduce the inter-piconet interference (IPI) and achieve greater throughput without much loss of link success probability (LSP) in the SOPs. The simulation results based on the SOPs of Direct Sequence Ultra Wideband (DS-UWB) system demonstrate that the proposed scheme effectively supports the coexistence of SOPs, and it can not only significantly improve the overall throughput of SOPs but also maintain high LSP.

• Journal of Multimedia Information System
• /
• 제5권4호
• /
• pp.273-276
• /
• 2018

In video compression standards, the entropy coding is essential to the high performance compression because redundancy of data symbols is removed. Binary arithmetic coding is one of high performance entropy coding methods. However, the dependency between consecutive binary symbols prevents improving the throughput. For the throughput enhancement, a new probability model is proposed for encoding multi-symbols at one time. In the proposed method, multi-symbol encoder is implemented with only adders and shifters, and the multiplication table for interval subdivision of binary arithmetic coding is removed. Compared to the compression ratio of CABAC of H.264/AVC, the performance degradation on average is only 1.4% which is negligible.

• 대한전자공학회논문지TC
• /
• 제45권9호
• /
• pp.8-12
• /
• 2008

본 논문에서는 AMC(Adaptive Modulation and Coding)기법을 적용한 D-STTD(Double-Space Time Transmit Diversity) 통신 시스템을 제안하고, 모의실험을 통해 그 성능을 분석한다. AMC기법은 채널 응답의 정보를 바탕으로 적절한 채널 코딩율과 변조 기법을 선택하여 신호를 전송하는 기법으로 에러율과 전송률의 적절한 조화를 이끌어내어 전체 시스템의 전송률과 전송품질의 향상을 가져온다. D-STTD기법은 기존의 STTD(Space Time Transmit Diversity)기법을 전송률 측면에서 보완한 기법으로 STTD기법에 비해 약 2배의 전송률 향상을 가져온다. 모의실험 결과, SNR(Signal to Noise Ratio)이 좋아질수록 높은 MCS(Modulation and Coding Scheme)레벨을 선택하는 확률이 높아지는 것을 볼 수 있었으며, AMC기법을 적용한 D-STTD 통신 시스템은 AMC기법을 적용하지 않은 D-STTD 통신 시스템에 비해 전 SNR구간에서 고른 전송률 분포를 나타냈다. 또한 AMC기법을 적용한 D-STTD 통신 시스템은 기존 AMC 통신 시스템, 혹은 AMC기법이 적용된 STTD 통신 시스템보다 2배 높은 최대 전송률을 나타내었다.

• ETRI Journal
• /
• 제38권6호
• /
• pp.1052-1063
• /
• 2016

We propose a millimeter wave (MMW)-based mobile hotspot network (MHN) system for application in high-speed railways that is capable of supporting a peak backhaul link throughput of 1 Gbps per train at 400 km/h. The MHN system can be implemented in subways and high-speed trains to support passengers with smart devices and provide access to the Internet. The proposed system can overcome the inherent high path loss in MMW through system designs and high antenna gains. We present a simulation of the system performance that shows that a fixed beamforming strategy can provide high signal-to-interference-plus-noise-ratio similar to those of an adaptive beamforming strategy, with the exception of 15% of the train path in which the network can use link adaptation with low-order modulation formats or trigger a handover to maintain the connection. We also demonstrate the feasibility of the MHN system using a test bed deployed in Seoul subway line 8. The backhaul link throughput varies instantaneously between 200 Mbps and 500 Mbps depending on the SNR variations while the train is running. During the field trial, the smartphones used could make connections through offloading.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제15권4호
• /
• pp.1342-1359
• /
• 2021

The data deduplication technique identifies the duplicates and minimizes the redundant storage data in the backup server. The chunk level deduplication plays a significant role in detecting the appropriate chunk boundaries, which solves the challenges such as minimum throughput and maximum chunk size variance in the data stream. To provide the solution, we propose a new chunking algorithm called Dynamic Prime Chunking (DPC). The main goal of DPC is to dynamically change the window size within the prime value based on the minimum and maximum chunk size. According to the result, DPC provides high throughput and avoid significant chunk variance in the deduplication system. The implementation and experimental evaluation have been performed on the multimedia and operating system datasets. DPC has been compared with existing algorithms such as Rabin, TTTD, MAXP, and AE. Chunk Count, Chunking time, throughput, processing time, Bytes Saved per Second (BSPS) and Deduplication Elimination Ratio (DER) are the performance metrics analyzed in our work. Based on the analysis of the results, it is found that throughput and BSPS have improved. Firstly, DPC quantitatively improves throughput performance by more than 21% than AE. Secondly, BSPS increases a maximum of 11% than the existing AE algorithm. Due to the above reason, our algorithm minimizes the total processing time and achieves higher deduplication efficiency compared with the existing Content Defined Chunking (CDC) algorithms.

• 한국콘텐츠학회논문지
• /
• 제9권7호
• /
• pp.67-75
• /
• 2009

최근 무선 인터넷 수요의 증가와 더불어 IEEE 802.11 WLAN의 표준화 작업도 활발히 진행 중이다. 고속처리량을 위한 IEEE 802.11n의 연구 동향은 크게 두 가지로 MAC 계층에서 패킷 간의 Aggregation을 통하여 시스템 처리량을 높인 결과와PHY 계층에서 MIMO 시스템을 적용하여 데이터 전송속도를 높인 결과로 정리될 수 있다. 그러나 아직까지 MAC 계층과 PHY 계층의 연동을 고려하여 IEEE 802.11n의 성능 분석을 보인 결과는 발표되지 않았다. 본 논문에서는 IEEE 802.11n 시스템에서 MAC 계층과 PHY 계층의 연동을 고려하여 성능을 분석한다. MAC 계층에서의 A-MPDU 기법과 PGY 계층에서 MIMO 방식을 적용한다. 결과적으로 기존의 방식에 비해 데이터 전송속도의 증가와 처리량이 향상되었음을 보인다. 또한, MAC과 PRY의 연동을 고려하여 현실성 있는 시뮬레이터인 NS-2를 사용하기로 한다.

• Nuclear Engineering and Technology
• /
• 제52권5호
• /
• pp.1008-1012
• /
• 2020

In order to make reasonable design for the improvement of comprehensive mechanical properties of RAFM steels, the design system with both machine learning and high-throughput optimization algorithm was established. As the basis of the design system, a dataset of RAFM steels was compiled from previous literatures. Then, feature engineering guided random forests regressors were trained by the dataset and NSGA II algorithm were used for the selection of the optimal solutions from the large-scale solution set with nine composition features and two treatment processing features. The selected optimal solutions by this design system showed prospective mechanical properties, which was also consistent with the physical metallurgy theory. This efficiency design mode could give the enlightenment for the design of other metal structural materials with the requirement of multi-properties.

• 생명과학회지
• /
• 제18권9호
• /
• pp.1312-1315
• /
• 2008

DAPI 염색을 이용하여 세포사멸 유도물질의 초고속스크리닝에 적합한 protocol을 제작하였다. Liquid handler에서 dispensing과 multilabel counter에서의 상대적인 fluorescent intensity를 측정하는 과정을 자동화한 protocol을 제작하였고, 이의 과정은 매우 효율적으로 가동되었음을 확인하였다. DAPI에 binding된 DNA의 intensity를 측정하는 조건검토에서 가장자리의 36개를 reading하지 않는 것이 edge effect를 줄일수 있는 것을 확인하였고, 0.1 sec reading으로 시간을 절약할 수 있었다. 이의 결과를 효과적으로 이용할 경우, 세포사멸 유도물질의 초고속스크리닝 또는 이에 적합한 스크리닝이 가능함을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제6권12호
• /
• pp.3237-3256
• /
• 2012

In the context of effective usage of a scarce spectrum resource, emerging wireless communication standards will demand spectrum sharing with existing systems as well as multiple access with higher spectral efficiency. We mathematically analyze the sum throughput of a spectrum sharing space-division multiple access (SDMA) system, which forms a transmit null in the direction of other coexisting systems while satisfying orthogonal beamforming constraints. For a large number of users N, the SDMA throughput scales as log N at high signal-to-noise ratio (SNR) ((J-1) loglog N at normal SNR), where J is the number of transmit antennas. This indicates that multiplexing gain of the spectrum sharing SDMA is $\frac{J-1}{J}$ times less than that of the non-spectrum sharing SDMA only using orthogonal beamforming, whereas no loss in multiuser diversity gain. Although the spectrum sharing SDMA always has lower throughput compared to the non-spectrum sharing SDMA in the non-coexistence scenario, it offers an intriguing opportunity to reuse spectrum already allocated to other coexisting systems.