• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.1
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• pp.58-73
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• 2014

As is well known, cooperative sensing can significantly improve the sensing accuracy as compared to local sensing in cognitive radio networks (CRNs). However, a large number of cooperative secondary users (SUs) reporting their local detection results to the fusion center (FC) would cause much overhead, such as sensing delay and energy consumption. In this paper, we propose a fast cooperative sensing scheme, called double threshold fusion (DTF), to reduce the sensing overhead while satisfying a given sensing accuracy requirement. In DTF, FC respectively compares the number of successfully received local decisions and that of failed receptions with two different thresholds to make a final decision in each reporting sub-slot during a sensing process, where cooperative SUs sequentially report their local decisions in a selective fashion to reduce the reporting overhead. By jointly considering sequential detection and selective reporting techniques in DTF, the overhead of cooperative sensing can be significantly reduced. Besides, we study the performance optimization problems with different objectives for DTF and develop three optimum fusion rules accordingly. Simulation results reveal that DTF shows evident performance gains over an existing scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.2
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• pp.550-565
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• 2018

Cognitive radio technology is still the key technology of future mobile communication systems. Previous studies have focused on improving spectrum utilization and less energy consumption. In this paper, we propose an Overhead Reduced Scheme (ORS) for green cooperative spectrum sensing. Compared to traditional cooperative sensing scheme, ORS scheme divides the sensing time into three time slots and selects the best multi-mode user to report decisions. In consideration of reporting channel deviation, we derive closed-form expressions for detection probability and false alarm probability of ORS scheme based on Rayleigh fading channel. Simulation results show that ORS scheme can improve the perception accuracy while reducing the perceived delay and energy consumption in the process of perception, so as to realize the green communication.

• Journal of Broadcast Engineering
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• v.22 no.6
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• pp.744-754
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• 2017

This paper compares transport overhead of MPEG-2 TS, MMT and ROUTE in order to compare transport efficiency between the DTV and UHDTV. The MPEG-2 TS standard, widely used, was established for multiplexing and synchronizing encoded audio and video, additional information. In recent years, MMT and ROUTE was established as a next generation multimedia transport standard for the new broadcasting communication environment. In this paper, we compare and analyze transport overhead about three protocol. In order to analysis, we captured the UHD A/V stream in real-time broadcasting service using ROUTE and MMT, and we calculated and analyzed transport overhead using the overhead analysis program which was developed in our laboratory. Furthermore, for comparison under the same conditions, we assumed the MPEG-2 TS stream by extracting ES of UHD A/V stream based on the DTV standard. In this paper, we show the results of protocol transport efficiency in case of basic A/V stream except for additional services. And result show that MMT and ROUTE have similar overhead and MPEG-2 TS is relatively small overhead. However, since MPEG-2 TS result does not consider null packets, it is expected that the relative overhead difference will be reduced.

• ETRI Journal
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• v.31 no.1
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• pp.83-85
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• 2009

Compared with unicast, multicast over wireless ad-hoc networks do not support reliability due to their inability to exchange request-to-send/clear-to-send (RTS/CTS) and ACK packets with multiple recipients. Although several media access control (MAC) layer protocols have been proposed to provide reliable multicast, these introduce additional overhead, which degrades system performance. A novel MAC protocol for reliable wireless multicast is proposed in this paper. By adapting orthogonal frequency division multiple access characteristics in CTS and ACK packets, the protocol achieves reliability over wireless multicast with minimized overhead.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.5-6
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• 2007

Routing protocol based on multi-rate previously Proposed has a advantage that it efficiently uses channel, but it has a disadvantage that it has a overhead that it increases control packets for route set up. Therefore, this paper propose a mechanism that decreases control packet overhead and simulates this mechanism using NS-2.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.3
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• pp.55-70
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• 2016

The most critical research issue in MANET environment is on supporting reliable communication between various devices. Various Multi-Hop Routing Protocol studies have proceeded. However, some problems you might have found when you use the existing link state routing technique are that it increases Control Message Overhead and it is unstable when node moves in CR circumstance which has transformation of using channel and MIMC circumstance which uses a number of interfaces. This essay offers a technique which is based on On-Demand Hello and the other technique which used Broadcast Interface of optimization as a solution to decrease Control Message Overhead. Also it proposes Quick Route Restoration technique which is utilized by GPS and MPR Selection technique which consider mobility as a solution of stable communication when node moves. Those offered Routing Protocol and OPNET based simulator result will be expected to be an excellent comparison in related research fields.

• Journal of Digital Convergence
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• v.13 no.5
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• pp.245-250
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• 2015

The P2P technology is becoming a technology for receiving a service, such as the latest YouTube and Facebook. P2P technology can be easily downloaded to a large amount of multimedia content over a distributed environment. However, pictures, music, a large amount of multimedia content such as videos each user is unable to manage the content management operating smoothly because, Song communication processing overhead caused when the reception is likely to remain the problem. In this paper, we propose a convergence content management technique that provides a low communication overhead of the frequency of use of the convergence content when trying to provide a large amount of convergence content to users in a distributed environment. Our method can be used to select the appropriate frequency is high among the shared content on the P2P multimedia environments that are distributed across a frequency of use of the convergence content and provides the service. Experimental evaluation proposed method, the convergence content browsing speed than conventional techniques improved communication about 13.3% and reduced overhead to about 9.5%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.10
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• pp.670-675
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• 2015

Degradation diagnosis of cable is one of major issues for operation and maintenance in overhead distribution power lines. The diagnostic system for overhead power lines is composed of three parts in functional aspect - a travelling unit, a sensing unit and a communication unit. Among them, sensor detects the defects such as corrosion and disconnecting of power lines. Performance of sensor is very important, and besides, the size and structure of sensor is restricted for installation to small and lightweight diagnostic system. This paper suggests an optimal eddy current sensor best suit for small and lightweight diagnostic system in consideration of detecting performance, size and ease of installation and so on. Proposed sensor has been designed by Drum core structure and can be applied to the all domestic overhead power lines regardless of the cross-sectional areas. Also, it is showed that results of mock environmental test are satisfied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1380-1386
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• 2011

The request of interrupt accompanies a context switching. If the interrupt is frequently requested, this overhead of context switching can reduce seriously the performance of embedded systems. In order to reduce processing overhead due to frequently requested communication interrupts at Asynchronous Serial Communication, this paper introduces the method of Expanded Asynchronous Serial Communication with the Interrupt Coalescence(IC) that accumulates a fixed number of interrupts and processes them in one time. we implement the existing Asynchronous Serial Communication that requests communication interrupts by one byte at an LN2440SBC embedded board with a uC/OS-II and compare interrupt processing time for the performance evaluation about proposed method. As a result, the communication interrupt processing time of proposed method appears in case of low speed(9,600 bps), the decline of an average 25.18% at transmission, the decline of an average 41.47% at reception. and in case of hight speed(115,200 bps), the decline of an average 16.67% at transmission, the decline of an average 25.61% at reception.

• The KIPS Transactions:PartA
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• v.14A no.4
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• pp.215-226
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• 2007

For past years, many distributed virtual shared-memory(DVSM) systems have been studied in order to develop a low-cost shared memory system with a fast interconnection network. But the DVSM needs a lot of data and control communication between distributed processing nodes in order to provide memory consistency in software, and this communication overhead significantly dominates the overall performance. In general, the communication overhead also increases as the number of processing nodes increase, so communication overhead is a very important performance factor for developing a large-scale DVSM system. In this paper, we study the performance scalability quantitatively and qualitatively for developing a large-scale DVSM system based on the next generation interconnection network, called the InfiniBand. Based on the study, we analyze a performance requirement of the next-coming interconnection network to be used for developing a performance-scalable DVSM system in the future.