• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권11호
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• pp.5276-5298
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• 2019

Internet of Things (IoT) based sensor networks have gained unprecedented popularity in recent years. With the exponential explosion of the objects (sensors and mobiles), the bandwidth and the speed of data transmission are dwarfed by the anticipated emergence of IoT. In this paper, we propose a novel heterogeneous IoT model integrated the power line communication (PLC) and WiFi network to increase the network capacity and cope with the rapid growth of the objects. We firstly propose the mean transmission delay calculation algorithm based the 3D Markov chain according to the multi-priority of the objects. Then, the attractor selection algorithm, which is based on the adaptive behavior of the biological system, is exploited. The combined the 3D Markov chain and the attractor selection model, named MASM, can select the optimal path adaptively in the heterogeneous IoT according to the environment. Furthermore, we verify that the MASM improves the transmission efficiency and reduce the transmission delay effectively. The simulation results show that the MASM is stable to changes in the environment and more applicable for the heterogeneous IoT, compared with the other algorithms.

• 한국통신학회논문지
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• 제37B권12호
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• pp.1102-1112
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• 2012

스마트폰의 급격한 보급에 따른 무선 접속망의 과부하 문제가 네트워크에서 중요한 문제로 부각되고 있다. 이 논문에서는 매크로 셀, 펨토 셀, 와이파이 접속망으로 다양하게 구성되어 있는 현재 이종 네트워크에서 접속망 과부하 문제를 해결하기 위한 최적의 셀 선정 기법과 리소스 할당 기법을 제안한다. 주어진 현재 서비스 부하 상태에서 네트워크가 동시에 추가 수용할 수 있는 사용자 수를 최대화할 수 있는 사용자-셀 간의 선정 기법을 제공한다. 이를 위해 이종 무선 접속망에서의 셀 선정 문제를 이진 정수계획 모형으로 최적화 문제를 수립하고, 이를 최적화 해법 도구를 이용하여 접속망 과부하를 억제할 수 있는 최적의 셀 선정 기법을 도출한다. 네트워크 레벨 시뮬레이션을 통해 이 논문에서 제안된 기법이 현재 무선 접속망에서 주로 사용되고 있는 국소적 셀 선정기법에 비해, 과부하가 걸린 무선 접속망에서 주어진 여러 셀들을 최대한 균등하게 효율적으로 활용함으로써 현저하게 네트워크 접속 장애율을 감소시킬 수 있음을 보인다. 또한 논문에서 사용된 이진 정수계획 모형의 최적화 문제를 푸는 데 소요되는 계산 복잡도에 대한 실험을 통해 제안된 알고리즘의 실용 가능성에 대해서 검증한다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1997년도 Proceedings International Workshop on New Video Media Technology
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• pp.49-54
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• 1997

For the purpose of a flexible coded video transmission over a heterogeneous network, we propose a new packetization method for coded video data. The proposed method achieves small degradation of coded picture quality in case of packet discard at the network node and does not require heavy processing load for bitrate control operation. Computer simulation results show that the bitrate reduction from 384 kb/s to 192 kb/s does not cause severe degradation in picture quality.

• Journal of Mechanical Science and Technology
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• 제19권8호
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• pp.1582-1596
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• 2005

Groundwater flow and behavior have to be investigated based on heterogeneous subsurface formation since the homogeneity assumption of this formation is not valid. Over the past twenty years, stochastic approach and Monte Carlo technique have been utilized very efficiently to understand the groundwater flow behavior. However, these techniques require lots of computational and numerical efforts according to the various researchers' comments. Therefore, utilizing new techniques with much less computational efforts such as Artificial Neural Network (ANN) in the prediction of the stochastic behavior for the groundwater based on heterogeneous subsurface formation is highly appreciated. The current paper introduces the ANN technique to investigate and predict the stochastic behavior of a well draw down in a confined aquifer based on subsurface heterogeneous hydraulic conductivity. Several ANN models are developed in this research to predict the unsteady two dimensional well draw down and its stochastic characteristics in a confined aquifer. The results of this study showed that ANN method with less computational efforts was very efficiently capable of simulating and predicting the stochastic behavior of the well draw down resulted from the continuous constant pumping in the middle of a confined aquifer with subsurface heterogeneous hydraulic conductivity.

• 전자공학회논문지CI
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• 제45권2호
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• pp.33-40
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• 2008

스트리밍 미디어는 유/무선망에서 미디어를 전송하기 위해 주로 이용되는 형태이며, TCP-friendly 비트율 제어 (TFRC)는 바로 이러한 스트리밍 미디어를 전송하기 위한 기술이다. TFRC는 TCP 혼잡상태 응답 기능과 현재의 망 상황정보를 이용하여, 최대 TCP-friendly throughput을 갖도록 전송율을 제어한다. 그러나 TFRC는 서서히 변하는 전송율을 생성하는 어플리케이션을 위하여 설계되었기 때문에 3G 망과 WLAN 등으로 이루어진 이종망 환경에서의 handover가 발생할 경우 매우 느린 전송율 반응을 보인다. 본 논문은 무선 이종망에서 vertical handover 경우를 위한 새로운 TFRC를 소개한다. 제안된 TFRC 방법은 새로운 망으로 handover할 경우 빠른 비트율 적응과 낮은 품질 저하현상을 갖는다. 시뮬레이션 결과를 통해 제안하는 방법이 vertical handover 동안에 전통적인 TFRC 방법보다 더 나은 QoS와 처리율을 제공함을 알 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권10호
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• pp.4662-4677
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• 2018

The dynamic opportunistic device-to-device (DO-D2D) network will frequently emerge in the fifth generation (5G) wireless communication due to high-density and fast-moving mobile devices. In order to improve the Quality of Experience (QoE) of users with different computing capacity devices in the DO-D2D network, in this paper, we focus on the study of how to reduce the packets retransmission delay and satisfy heterogeneous devices. To select as many devices as possible to transmit simultaneously without interference, the concurrent transmitters-selecting algorithm is firstly put forward. It jointly considers the number of packets successfully received by each device and the device's connectivity. Then, to satisfy different devices' demands while primarily ensuring the base-layer packets successfully received by all the devices, the layer-cooperation instantly decodable network coding is presented, which is used to select transmission packets combination for each transmitter. Simulation results illustrate that there is an appreciable retransmission delay gain especially in the poor channel quality network compared to the traditional base-station (BS) retransmission algorithm. In addition, our proposed algorithms perform well to satisfy the different demands of users with heterogeneous devices.

• 디지털콘텐츠학회 논문지
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• 제18권5호
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• pp.983-987
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• 2017

다중 홈 이동 라우터(multi-homing mobile router)는 사용자 디바이스 접속을 위한 네트워크와 인터넷에 접속하는 네트워크를 분리하고 인터넷 접속을 위한 다양한 인터페이스를 가지게 된다. 본 논문에서는 이기종 네트워크 인터페이스를 가지는 이동 라우터에서 IP 기반 이동성을 지원하며 각 인터페이스 간의 부하 분산을 위한 메트릭을 제안한다. 제안한 이동 라우터의 부하 균등 메트릭을 한국과 홍콩의 실제 상용 망에 적용하여 성능을 측정하였다.

• ETRI Journal
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• 제42권5호
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• pp.686-699
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• 2020

In this paper, we propose a supervised-learning-based spatial performance prediction (SLPP) framework for next-generation heterogeneous communication networks (HCNs). Adaptive asset placement, dynamic resource allocation, and load balancing are critical network functions in an HCN to ensure seamless network management and enhance service quality. Although many existing systems use measurement data to react to network performance changes, it is highly beneficial to perform accurate performance prediction for different systems to support various network functions. Recent advancements in complex statistical algorithms and computational efficiency have made machine-learning ubiquitous for accurate data-based prediction. A robust network performance prediction framework for optimizing performance and resource utilization through a linear discriminant analysis-based prediction approach has been proposed in this paper. Comparison results with different machine-learning techniques on real-world data demonstrate that SLPP provides superior accuracy and computational efficiency for both stationary and mobile user conditions.

• Journal of Communications and Networks
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• 제18권1호
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• pp.112-122
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• 2016

Cognitive radio (CR) is considered an attractive technology to deal with the spectrum scarcity problem. Multi-radio access technology (multi-RAT) can improve network capacity because data are transmitted by multiple RANs (radio access networks) concurrently. Thus, multi-RAT embedded in a cognitive radio network (CRN) is a promising paradigm for developing spectrum efficiency and network capacity in future wireless networks. In this study, we consider a new CRN model in which the primary user networks consist of heterogeneous primary users (PUs). Specifically, we focus on the energy-efficient resource allocation (EERA) problem for CR users with a special location coverage overlapping region in which heterogeneous PUs operate simultaneously via multi-RAT. We propose a two-tier crossover genetic algorithm-based search scheme to obtain an optimal solution in terms of the power and bandwidth. In addition, we introduce a radio environment map to manage the resource allocation and network synchronization. The simulation results show the proposed algorithm is stable and has faster convergence. Our proposal can significantly increase the energy efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.3789-3809
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• 2015

In this paper, we deal with the problem of M2M gateways' network selection for different types of M2M traffic in heterogeneous wireless networks. Based on the difference in traffic's quality of service (QoS) requirements, the M2M traffic produced by various applications is mainly classified as two categories: flexible traffic and rigid traffic. Then, game theory is adopted to solve the problem of network-channel selection with the coexistence of flexible and rigid traffic, named as flexible network access (FNA). We prove the formulated discrete game is a potential game. The existence and feasibility of the Nash equilibrium (NE) of the proposed game are also analyzed. Then, an iterative algorithm based on optimal reaction criterion and a distributed algorithm with limited feedback based on learning automata are presented to obtain the NE of the proposed game. In simulations, the proposed iterative algorithm can achieve a near optimal sum utility of whole network with low complexity compared to the exhaustive search. In addition, the simulation results show that our proposed algorithms outperform existing methods in terms of sum utility and load balance.