• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권12호
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• pp.5191-5211
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• 2016

It is essential to satisfy class-specific QoS constraints to provide broadband services for new generation networks. The present study proposes a QoS-driven multicast scheme for wireless networks in which the transmission rate and end-to-end delay are assumed to be bounded during a multiple multicast session. A distributed algorithm was used to identify a cost-efficient sub-graph between the source and destination which can satisfy QoS constraints of a multicast session. The model was then modified as to be applied for wireless networks in which satisfying interference constraints is the main challenge. A discrete power control scheme was also applied for the QoS-aware multicast model to accommodate the effect of transmission power level based on link capacity requirements. We also proposed random power allocation (RPA) and gradient power allocation (GPA) algorithms to efficient resource distribution each of which has different time complexity and optimality levels. Experimental results confirm that the proposed power allocation techniques decrease the number of unavailable links between intermediate nodes in the sub-graph and considerably increase the chance of finding an optimal solution.

• 한국콘텐츠학회논문지
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• 제18권3호
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• pp.611-625
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• 2018

최근 무선 통신 기술의 혁신적인 발전에 따라 에너지 하베스팅을 통해 네트워크 수명을 영구적으로 연장하기 위한 네트워크 자원 최적화, QoS 보장 전송 기법, 에너지 지능적 라우팅 등의 연구가 활발히 진행되고 있다. 잘 알려진 바와 같이 다중-홉 RF 에너지 하베스팅 무선 네트워크에서는 수확되는 에너지양의 불확실성 때문에 종단간 네트워크 전송 지연 시간을 보장하기 어려운 문제가 발생한다. 본 논문에서는 다중 홉 에너지 하베스팅 무선 네트워크에서 종단간 지연 시간을 최소화하기 위하여 상호채널 간섭(co-channel interference)으로 인한 지연, 에너지 하베스팅 시간으로 인한 지연 그리고 중계 노드에서의 큐잉 지연을 종합적으로 고려한 간섭 인지 기반의 에너지 효율적인 라우팅 메트릭과 프로토콜을 제안한다. 제안된 기법은 부하 불균형을 유발하는 패킷 혼잡을 회피하고 에너지 고갈로 인한 노드의 대기 시간을 줄이며 링크 간의 간섭으로 지연시간이 증가되지 않도록 함으로써 종단간 처리량을 최대화한다. 마지막으로 ns-3 시뮬레이터를 이용하여 처리율, 종단간 지연시간, 에너지 소비량 등의 측면에서 제안된 기법의 성능을 측정하여 기존에 제안된 기법보다 성능이 우수함을 증명한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권3호
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• pp.945-964
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• 2014

In this paper, we investigate the performance of Signal to Leakage and Noise Radio (SLNR) based user scheduling in uplink of multi-cell with large-scale antenna system. Large antenna array is desired to improve the performance in future system by providing better beamforming capability. However, some studies have found that the signal channel is 'hardened' (becomes invariant) when the antenna number goes extremely large, which implies that the signal channel aware user scheduling may have no gain at all. With the mathematic tool of order statistics, we analyzed the signal and interference terms of SLNR in a homogeneous multicell network. The derived distribution function of signal and interference shows that the leakage channel's variance is much more influential than the signal channel's variance in large-scale antenna regime. So even though the signal channel is hardened, the SLNR-based scheduling can achieve remarkable multiuser diversity (MUD) gain due to the fluctuation of the uplink leakage channel. By providing the final SINR distribution, we verify that the SLNR-based scheduling can leverage MUD in a better way than the signal channel based scheduling. The Monte Carlo simulations show that the throughput gain of SLNR-based scheduling over signal channel based scheduling is significant.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권2호
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• pp.1057-1069
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• 2017

The applications of Wireless Sensor Networks (WSN) are progressively adopting for various smart home services such as home automation, controlling smart home household appliances, constrained application services in a smart home, etc. However, enabling a seamless and ubiquitous WSN communication between the smart home appliances is still a challenging job. Therefore, in this paper, we propose a smart home control system using an Actuator based ZigBee networking (AZNET). The working of the proposed system is further divided into three phases, 1) an interference avoidance system is adopted to mitigate the effect of interference caused due to the co-existence of IEEE 802.11x based wireless local area networks (WLAN) and WSN, 2) a sensor-based smart light control system is used to fulfill the light requirement in the smart home using the sunlight with light source, and 3) an autonomous home management system is used to regulate the usage time of the electronic appliances in the smart home. The smart is tested in real time environment to use the sunlight with light sources in a various time of the day. Similarly, the performance of the proposed smart home is verified through simulation using C# programming language. The results and analysis revealed that the proposed smart home is less affected by the interference and efficient in reducing the energy consumption of the appliances available in the smart home scenario.

• Journal of Information Processing Systems
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• 제12권2호
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• pp.295-309
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• 2016

Spectrum sensing is an essential function that enables cognitive radio technology to explore spectral holes and resourcefully access them without any harmful interference to the licenses user. Spectrum sensing done by a single node is highly affected by fading and shadowing. Thus, to overcome this, cooperative spectrum sensing was introduced. Currently, the advancements in multiple antennas have given a new dimension to cognitive radio research. In this paper, we propose a multiple energy detector for cooperative spectrum sensing schemes based on the evidence theory. Also, we propose a reporting mechanism for multiple energy detectors. With our proposed system, we show that a multiple energy detector using a cooperative spectrum sensing scheme based on evidence theory increases the reliability of the system, which ultimately increases the spectrum sensing and reduces the reporting time. Also in simulation results, we show the probability of error for the proposed system. Our simulation results show that our proposed system outperforms the conventional energy detector system.

• 전기학회논문지
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• 제63권9호
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• pp.1273-1280
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• 2014

This paper considers a GPS anti-spoofing problem. Spoofing is an intentional interference that mislead the GNSS receiver. The spoofing attack is very significant since the target receiver is not aware of being attacked from spoofing. Accelerometers can be used to detect the spoofing signal by being compared with the acceleration obtained from GPS information using Kalman filter. In this paper we propose an N by N-point average and M-point window algorithm to detect GPS spoofing by using accelerometers and GPS outputs. The performance of the proposed algorithm is analyzed using actual vehicle trajectory and spoofing trajectory generated from INS and GPS toolbox for simulation.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2013년도 하계학술대회
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• pp.27-28
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• 2013

본 논문에서는 간섭 제한 적인 상황에서 지정된 채널을 추정해야 하는 실제적인 무선 애드혹 네트워크에서 비모수 선형 MMSE 필터 기반의 간섭 제어 채널 추정 기법을 사용하여 네트워크 성능을 개선시키는 새로운 기법을 제안한다. 제안하는 채널 추정 기법은 간섭의 정도에 따라 노드를 활성화 시키고 지정된 채널 추정을 한다. 실제적인 무선 애드혹 네트워크 모의실험을 통해 제안된 기법이 기존의 채널 추정 기법에 비해 상당한 전송 캐패시티 이득을 얻을 수 있음을 확인할 수 있다.

• Journal of Computing Science and Engineering
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• 제6권4호
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• pp.257-266
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• 2012

This paper overviews clock design problems related to the circuit reliability in deep submicron design technology. The topics include the clock polarity assignment problem for reducing peak power/ground noise, clock mesh network design problem for tolerating clock delay variation, electromagnetic interference aware clock optimization problem, adjustable delay buffer allocation and assignment problem to support multiple voltage mode designs, and the state encoding problem for reducing peak current in sequential elements. The last topic belongs to finite state machine (FSM) design and is not directly related to the clock design, but it can be viewed that reducing noise at the sequential elements driven by clock signal is contained in the spectrum of reliable circuit design from the clock source down to sequential elements.

• 한국IT서비스학회:학술대회논문집
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• 한국IT서비스학회 2010년도 춘계학술대회
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• pp.207-210
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• 2010

무선 센서 네트워크 시스템을 이용한 많은 응용 시스템이 연구되고 있는 가운데, 최근 무선 센서 네트워크 시스템의 신뢰성 확보에 대한 문제점이 대두되었다. 이러한 문제점을 해결하기 위하여 영상 데이터를 전송함으로써 보다 신뢰성 있는 정보를 제공할 수 있는 멀티미디어 센서 네트워크에 대한 연구가 활발히 진행되고 있다. 그러나 영상 데이터를 저속의 멀티 홉 무선 센서 네트워크 환경에서 효율적으로 전송하는 프로토콜에 관련된 연구는 비교적 많지 않다. 지금까지의 통신 프로토콜들은 비교적 단순한 센싱 데이터를 전송할 수 있도록 설계되었으며, 새로운 응용들을 지원하기 위해서는 새로운 통신 프로토콜이 필요하다. 따라서 본 논문에서는 연속적인 영상 데이터를 멀티 홉 환경에서 효율적으로 전송할 수 있는 다중 경로 간 간섭이 없는 간섭 회피 다중 경로 설정 기법을 제안한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.57-58
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• 2006

Ad hoc MAC protocols using directional antennas can be used to improve the network capacity by improving spatial reuse. But, the directional MAC protocols have the problem of deafness and have a poor throughput performance. The dual-channel DMAC protocol has been proposed to mitigate deafness and improve spatial reuse. In this paper, we propose a dual-channel DMAC protocol using the omnidirectional antenna for an out-of-band tone and directional antennas for control/data channels. In the proposed MAC protocol, an omnidirectional out-of-band tone mitigates deafness and directional antennas used in control/data channels improve spatial reuse and reduce interference packets. The throughput performance of the proposed MAC protocol is confirmed by computer simulations using Qualnet ver. 3.8 simulator.