• Journal of the Korea Society of Computer and Information
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• v.13 no.5
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• pp.195-202
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• 2008

In this paper, To improve the effectiveness of security enforcement, the first contribution in this work is that we present a clustered heterogeneous WSN(Wareless Sensor Network) architecture, composed of not only resource constrained sensor nodes, but also a number of more powerful high-end devices acting as cluster heads. Compared to sensor nodes, a high-end cluster head has higher computation capability, larger storage, longer power supply, and longer radio transmission range, and it thus does not suffer from the resource scarceness problem as much as a sensor node does. A distinct feature of our heterogeneous architecture is that cluster heads are equipped with TC(trusted computing) technology, and in particular a TCG(Trusted Computing Group) compliant TPM (Trusted Platform Module) is embedded into each cluster head. According the TCG specifications, TPM is a tamper-resistant, self-contained secure coprocessor, capable of performing cryptographic functions. A TPM attached to a host establishes a trusted computing platform that provides sealed storage, and measures and reports the integrity state of the platform.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.7 s.361
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• pp.70-80
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• 2007

For supporting various mobile networks, this paper proposes a framework of distributed connection admission control, named SmartCAC. Especially, intelligent CAC operations are adopted in terms of interoperation between mobile nodes and mobile networks. This scheme does not need to correct information between networks. Basically vertical handover call can use guard channel that was reserved for handoff, because SmartCAC addresses the identification between vertical handover call and new call, delay and reliability as requirement of QoS for efficient connection control. The scheme also uses mobile terminal speed for network filtering. Especially an extended protocol is proposed to give different network states information to mobile nodes because there have been no ways for mobile nodes to compare the states of different networks. Sophisticated simulation study is performed in order to evaluate SmartCAC in terms of signaling cost. As a result, signaling cost of ours is up to 96% better than that of the existing scheme.

• Journal of Information Processing Systems
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• v.17 no.1
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• pp.63-74
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• 2021

According to the double-phase cluster-head election method (DCE), the final cluster heads (CHs) sometimes are located at the edge of cluster. They have a long distance from the base station (BS). Sensor data is directly transmitted to BS by CHs. This makes some nodes consume much energy for transmitting data and die earlier. To address this problem, energy efficient multi-hop cluster-head election strategy (EEMCE) is proposed in this paper. To avoid taking these nodes far from BS as CH, this strategy first introduces the distance from the sensor nodes to the BS into the tentative CH election. Subsequently, in the same cluster, the energy of tentative CH is compared with those of other nodes, and then the node that has more energy than the tentative CH and being nearest the tentative CH are taken as the final CH. Lastly, if the CH is located at the periphery of the network, the multi-hop method will be employed to reduce the energy that is consumed by CHs. The simulation results suggest that the proposed method exhibits higher energy efficiency, longer stability period and better scalability than other protocols.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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• pp.5446-5463
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• 2019

Parallel computing system components should be harmonized, and this harmonization is kept existent using synchronization time. Synchronization time affects the system in two ways. First, if we have too little synchronization time, some tasks face the problem of harmonization, as they need appropriate time to update and synchronize with the system. Second, if we allocate a large amount of time, stall system created. Random allocation of synchronization time for parallel systems slows down not only the booting time of the system but also the execution time of each application involved in the system. This paper presents a simulator used to test and allocate appropriate synchronization time for distributed and parallel heterogeneous systems. The simulator creates the parallel and heterogeneous system to be evaluated, and lets the user vary the synchronization time to optimize the booting time. NS3-cGEM5 simulator in this paper is formed by HLA-RTI federation integration of the two independent architecture and network simulators - NS3 and cGEM5. Therefore, nodes created on these simulators need synchronizations for harmonized system performance. We tested and allocated the appropriate synchronization time for our sample parallel system composed of one x86 server and three ARM clients.

• Journal of Internet Computing and Services
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• v.3 no.6
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• pp.53-61
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• 2002

This paper propose an dynamic load balancing algorithm for heterogeneous distributed systems. The algorithm allows this tasks to be relocated. The key of the algorithm is to transfer a suitable amount of processing demand from senders to receivers. This amount is determined dynamically during sender-receiver negotiations. Factors considered when this amount is determined include processing speeds of different nodes, the current load state of both sender and receiver, and the processing demands of tasks eligible for relocation. This paper also propose a load state measurement scheme which is designed particularly for heterogeneous systems. This results of the study show that the proposed algorithm outperforms the existing algorithms and is stable over a range of system attributes.

• Journal of Communications and Networks
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• v.13 no.4
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• pp.367-376
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• 2011

In this paper, we propose self-organizing schemes for the initial configuration of the neighbor cell list (NCL), maintenance of the NCL, and physical cell identifier (PCI) allocation in heterogeneous networks such as long term evolution systems where lower transmission power nodes are additionally deployed in macrocell networks. Accurate NCL maintenance is required for efficient PCI allocation and for avoiding handover delay and redundantly increased system overhead. Proposed self-organizing schemes for the initial NCL configuration and PCI allocation are based on evolved universal terrestrial radio access network NodeB (eNB) scanning that measures reference signal to interference and noise ratio and reference symbol received power, respectively, transmitted from adjacent eNBs. On the other hand, the maintenance of the NCL is managed by adding or removing cells based on periodic user equipment measurements. We provide performance analysis of the proposed schemes under various scenarios in the respects of NCL detection probability, NCL false alarm rate, handover delay area ratio, PCI conflict ratio, etc.

• Journal of Korea Multimedia Society
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• v.20 no.11
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• pp.1776-1784
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• 2017

There are two types of WSN(wireless sensor networks) in terms of sensor node's capability, that is, homogeneous or heterogeneous WSN. Even though the latter has better performance than the former, it requires some overhead for deploying nodes or clustering the network. In this paper, we propose a new scheme, called VHS(Virtual Heterogenous Sensor-Network), which uses a homogeneous WSN regarding energy in a heterogeneous way. The proposed scheme's performance has been evaluated and compared with other homogeneous schemes by simulation. The results are shown to be better than the other existing homogeneous schemes used in a sample sensor network application.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4451-4466
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• 2014

We present joint radio selection and relay scheme that delivers data from a source to a sink in heterogeneous stationary sensor networks consisting of various radio interfaces. The proposed scheme finds the optimal relay nodes and their corresponding radio interfaces that minimize energy consumption throughout the network while satisfying the end-to-end packet deadline requirement. We formulate the problem of routing through radio interface selection into binary integer programs, and obtain the optimal solution by solving with an optimization solver. We examine a trade-off relationship between energy consumption and packet delay based on network level simulations. We show that given the end-to-end deadline requirement, our routing algorithm finds the most energy-efficient routing path and radio interface across mesh hops. We demonstrate that the proposed routing scheme exploits the given packet delivery time to turn into network benefit of reducing energy consumption compared to routing based on single radio interface.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.147-161
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• 2012

In recent years, machine-to-machine (M2M) communications are under rapid development to meet the fast-increasing requirements of multi-type wireless services and applications. In order to satisfy M2M communications requirements, heterogeneous networks convergence appears in many areas, i.e., mobile cellular networks (MCNs) and wireless sensor networks (WSNs) are evolving from heterogeneous to converged. In this paper, we introduce the system architecture and application requirement for converged MCN and WSN, where mobile terminals in MCN are acting as both sensor nodes and gateways for WSN. And then, we discuss the joint optimization of converged networks for M2M communications. Finally, we discuss the technical challenges in the converged process of MCN and WSN.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.367-370
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• 2017

This paper proposes a method for selecting efficient relay nodes in stochastic DTN model. Delay Tolerant Network (DTN) uses the Carry and Forward method, which creates a bundle layer for efficient communication, selects relay nodes between different networks and heterogeneous networks, and forwards messages. DTN is basically composed of mobile nodes so DTN has no fixed routing route and it has long latency due to intermittent connection. Therefore, the nodes constituting the DTN necessarily have the characteristics to store the messages, and the capacity of the stored messages and nodes affects the performance of the network. Stochastic DTN model proposed a Markov model that changes randomly over time to analyze the performance of DTN. In this paper, we use stochastic message distribution and node contact probabilities using contact time analyzed through message generation and extinction in order to select efficient relay nodes in stochastic DTN model.