• Journal of Korea Multimedia Society
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• v.21 no.6
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• pp.667-677
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• 2018

Since sensor networks consist of sensor nodes with limited energy resources, so efficient energy use of sensor nodes is very important in the design of sensor networks. Sensor nodes consume a lot of energy for data transmission. Clustering technique is used to efficiently use energy in data transmission. Recently, mobile sink techniques have been proposed to reduce the energy load concentrated on the cluster header near a sink node. The CMS(Cluster-based Mobile sink) technique minimizes the generation of control messages by creating a data transmission path while creating clusters, and supports the inter-cluster one-hop transmission. But, there is a case where there is no connectivity between neighbor clusters, it causes a problem of having a long hop data transmission path regardless of local distance. In this paper, we propose a SCBC(Strong connection balancing cluster) to support the path of the minimum number of hops. The proposed scheme minimizes the number of hops in the data transmission path and supports efficient use of energy in the cluster header. This also minimizes a number of hops in data transmission paths even when the sink moves and establishes a new path, and it supports the effect of extending the life cycle of the entire sensor network.

• Journal of Korea Multimedia Society
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• v.20 no.4
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• pp.640-648
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• 2017

Sensors have limited resources in sensor networks, so efficient use of energy is important. In order to use the energy of the sensor node efficiently, researches applying mobile sink to the sensor network have been actively carried out. The sink node moves the sensor network, collects data from each sensor node, which spread the energy concentrated around the sink node, thereby extending the entire life cycle of the network. But, when the sink node moves, it requires a reset of the data transmission path, which causes a lot of control messages and delays. In this paper, we propose a CMS(Cluster-based Mobile Sink) method to support the movement of mobile sink in a cluster sensor environment. The proposed scheme minimizes an amount of control messages without resetting the routing paths of entire sensor networks by supporting the sink mobility path using the neighbor cluster list. And, it simplifies the routing path setup process by setting a single hop path between clusters without a gateway. The experiment results show that the proposed scheme has superior energy efficiency in processing and network structure, compared with existing clustering and mesh routing protocols.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.6
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• pp.1133-1151
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• 2010

Energy balanced consumption routing is based on assumption that the nodes consume energy both in transmitting and receiving. Lopsided energy consumption is an intrinsic problem in low-cost sensor networks characterized by multihop routing and in many traffic overhead pattern networks, and this irregular energy dissipation can significantly reduce network lifetime. In this paper, we study the problem of maximizing network lifetime through balancing energy consumption for uniformly deployed low-cost sensor networks. We formulate the energy consumption balancing problem as an optimal balancing data transmitting problem by combining the ideas of corona cluster based network division and optimized transmitting state routing strategy together with data transmission. We propose a localized cluster based routing scheme that guarantees balanced energy consumption among clusters within each corona. We develop a new energy cluster based routing protocol called "OECR". We design an offline centralized algorithm with time complexity O (log n) (n is the number of clusters) to solve the transmitting data distribution problem aimed at energy balancing consumption among nodes in different cluster. An approach for computing the optimal number of clusters to maximize the network lifetime is also presented. Based on the mathematical model, an optimized energy cluster routing (OECR) is designed and the solution for extending OEDR to low-cost sensor networks is also presented. Simulation results demonstrate that the proposed routing scheme significantly outperforms conventional energy routing schemes in terms of network lifetime.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.11
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• pp.5322-5342
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• 2016

In vehicle-to-vehicle (V2V) networks, where selfishness degrades node activity, countermeasures for collaboration enforcement must be provided to enable application of a sage and efficient network environment. Because vehicular networks feature both high mobility and various topologies, selfish behavior judgment and establishment of a stable routing protocol become intensely challenging. In this paper, a two-phase-based generous cooperative routing protocol (called GEC) is presented for V2V networks to provide resistance to selfishness. To detect selfish behaving vehicles, a packet forwarding watchdog and an average connection rate based on the multipath weight method are used, where evidence is gathered from different watchdogs. Then, multihop relay decisions are made using a generous cooperative algorithm based on game theory. Finally, through buffering of the multiple end-to-end paths and judicious choice of optimal cooperative routes, route maintenance phase is capable of dealing with congestion and rapidly exchanging traffic. Specifically, it is proved that the GEC is theoretically subgame perfect. Simulation results show that for V2V networks with inherently selfish nodes, the proposed method isolates uncooperative vehicles and is capable of accommodating both the mobility and congestion circumstances by facilitating information dissemination and reducing end-to-end delay.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.574-592
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• 2016

Range-free localization algorithm computes a normal node's position by estimating the distance to anchors which know their actual position. In recent years, reliable anchor selection research has been gained a lot of attention because this approach improves localization accuracy by selecting the only subset of anchors called reliable anchor. The distance estimation accuracy and the geometric shape formed by anchors are the two important factors which need to be considered when selecting the reliable anchors. In this paper, we study the relationship between a relative position of three anchors and localization error. From this study, under ideal condition, which is with zero localization error, we find two conditions for anchor selection, thereby proposing a novel anchor selection algorithm that selects three anchors matched most closely to the two conditions, and the validities of the conditions are proved using two theorems. By further employing the conditions, we finally propose a novel range-free localization algorithm. Simulation results show that the proposed algorithm shows considerably improved performance as compared to other existing works.

• Journal of Communications and Networks
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• v.15 no.3
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• pp.266-275
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• 2013

The exact closed-form expressions for outage probability and bit error rate of spectrum sharing-based multi-hop decode-and-forward (DF) relay networks in non-identical Rayleigh fading channels are derived. We also provide the approximate closed-form expression for the system ergodic capacity. Utilizing these tractable analytical formulas, we can study the impact of key network parameters on the performance of cognitive multi-hop relay networks under interference constraints. Using a linear network model, we derive an optimum relay position scheme by numerically solving an optimization problem of balancing average signal-to-noise ratio (SNR) of each hop. The numerical results show that the optimal scheme leads to SNR performance gains of more than 1 dB. All the analytical expressions are verified by Monte-Carlo simulations confirming the advantage of multihop DF relaying networks in cognitive environments.

• Journal of Communications and Networks
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• v.16 no.4
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• pp.371-377
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• 2014

Localized topology control is attractive for obtaining reduced network graphs with desirable features such as sparser connectivity and reduced transmit powers. In this paper, we focus on studying how to prolong network lifetime in the context of localized topology control for wireless multi-hop networks. For this purpose, we propose an energy efficient localized topology control algorithm. In our algorithm, each node is required to maintain its one-hop neighborhood topology. In order to achieve long network lifetime, we introduce a new metric for characterizing the energy criticality status of each link in the network. Each node independently builds a local energy-efficient spanning tree for finding a reduced neighbor set while maximally avoiding using energy-critical links in its neighborhood for the local spanning tree construction. We present the detailed design description of our algorithm. The computational complexity of the proposed algorithm is deduced to be O(mlog n), where m and n represent the number of links and nodes in a node's one-hop neighborhood, respectively. Simulation results show that our algorithm significantly outperforms existing work in terms of network lifetime.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.1049-1052
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• 2009

This paper develop a intelligent personal emergency call system using the wireless sensor network to resolve that a portable problem of established emergency call system. The proposed system is composed of a transmitter nodes for individuals, routing nodes for multihop communications, and a server part. The transmitters for patients are monitored for both low battery and operational status. The transmitters provide location of the person activating an emergency call using RSSI. The efficacy of the proposed system is verified by means of experiments. Experimental results are presented that show the effectiveness.

• Journal of KIISE:Information Networking
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• v.34 no.5
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• pp.328-339
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• 2007

Conventional topology-based routing protocols are not suitable for inter-vehicular communication, where frequent route updates are necessary due to continuous and abrupt changes in network topology Position-based routing protocols are widely accepted to better serve their purpose in such a scenario as they do not require path discovery or maintenance. However they have to deal with the overhead of the location service and inaccurate position information. This paper proposes the MMFP (Multi-hop MAC Forwarding Protocol) for inter-vehicle communication that relies on reachability information collected from received packets in making a forwarding decision without path discovery. The MMFP is designed as an extension to the IEEE 802.11 MAC layer to ensure accuracy in its time-critical operations. This paper also presents some simulation results that demonstrate the superior performance of the MMFP over AODV in a realistic inter-vehicular communication.

• Journal of IKEEE
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• v.18 no.3
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• pp.427-434
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• 2014

The Multihop Routing of vehicle communication environment is difficult to maintain due to heavy fluctuation of network topology and routing channel according to the movement of the vehicle, road property, vehicle distribution. We implemented GeoNetworking on the basis of ETSI(European Telecommunication Standard Institute) to maintain the vehicle safety service. GeoNetworking has its own way that delivers the data through the Unicast and Broadcast. In this paper, we compared performance index such as packet delivery ratio, end-to-end delay about GeoNetworking using the QualNet Network Simulator. Previous research assessed performance of GeoUnicast. This research has been additionally performed about GeoBroadcast, and we progressed algorithm performance through the comparison of CBF(Contention based Forwarding) of GeoUnicast with Greedy forwarding of GeoBroadcast.