• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.5
• /
• pp.207-215
• /
• 2014

In this paper, we propose a Micro Real-Time Control System (MRTCS) for decreasing the delay during interrupts processing and data transfer on sensor nodes. The MRTCS consists of a control, sensor nodes based on Controller Area Network (CAN) device. The control node was designed with Real Time Operating System (RTOS) on top of the small Micro Control Unit (sMCU). Sensor nodes have the CAN device without sMCU, which have multiple Digital Inputs, Outputs (DI/DO) and the CAN controller. We have evaluated with OCTAVE v3.6.4 from open source for system performance. Simulation results show that the system performance was increased through the delay reducing for interrupt processing and internal data transfer. We verify that a proposed MRTCS approach will be adapted to various real-time control system.

• The Journal of the Korea Contents Association
• /
• v.12 no.7
• /
• pp.21-28
• /
• 2012

The data centric storage (DCS) scheme is one of representative methods to efficiently store and maintain data generated in wireless sensor networks. In the DCS schemes, each node has the specified data range for storing data. This feature is highly vulnerable to the faults of nodes. In this paper, we propose a new recovery scheme for the lost data caused by the faults of nodes in DCS environments. The proposed scheme improves the accuracy of query results by recovering the lost data using the spatial continuity of physical data. To show the superiority of our proposed scheme, we simulate it in the DCS environments with the faults of nodes. In the result, our proposed scheme improves the accuracy by about 28% through about 2.5% additional energy consumption over the existing scheme.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.10B
• /
• pp.955-963
• /
• 2009

In this paper, we propose a medium access control(MAC) protocol for reducing the energy efficiency and for improving the transmission efficiency in underwater acoustic sensor networks. In underwater environment, the transmission delay is longer and bandwidth is smaller than terrestrial environment. Considering these points, we propose a new MAC protocol to enhance throughput and to manage efficiently the energy of nodes. The proposed protocol operates as a channel reservation scheme to decrease data collisions, and uses a mechanism to control the hidden node problem and the exposed node problem occurred in ad hoc networks. The proposed protocol consists of the slotted based transmission frame and reduces data collisions between nodes by putting separately the reservation period in the transmission frame. In addition, it is able to solve the hidden node problem and the exposed node problem by reservation information between nodes. We carry out the simulation to evaluate the proposed protocol in terms of the average energy consumption, the ratio of collision, throughput, and the average transmission delay, and compare the proposed protocol to a traditional MAC protocol in the underwater environment. The simulation results show that the proposed protocol outperforms the traditional protocol under a various of network parameters.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.14 no.6
• /
• pp.125-132
• /
• 2015

This paper presents an event data delivery scheme for wireless sensor networks that use a GTS-based channel allocation scheme. Many sensor nodes can share a GTS channel for sending their normal data to the sink node. When there is an event at a node, the node makes a temporal route to the sink node and the nodes of the route can use the GTS channel in a privileged access. This scheme controls the backoff number effectively so the data delivery priority is given to the nodes of that route. Simulation results show that the event data delivery of the proposed scheme outperforms at the end-to-end transfer delay and jitter characteristics. The proposed scheme can effectively gather the event data using the guaranteed GTS channel of the route in proposed scheme.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.397-400
• /
• 2015

In this paper a solar energy harvesting system with low-cost MPPT control for low duty-cycled sensor nodes is proposed. The targeted applications are environment, structure monitoring sensor nodes that are not required successively to operate, and MPPT(Maximum Power point Tracking) control using simple circuits is low-cost differently than existing MPPT control. The proposed MPPT control is implemented using linear relationship between the open-circuit voltage of a solar cell. The designed MPPT circuit traces the maximum power point by sampling periodically the open circuit voltage of the solar cell and delivers the maximum available power to the load. The proposed circuit is designed in 0.35um CMOS process. The designed chip area is $975um{\times}1025um$ including pads. Measured results show that the designed system can track the MPP voltage by sampling periodically the open circuit voltage of solar cell.

• Journal of Communications and Networks
• /
• v.11 no.4
• /
• pp.337-349
• /
• 2009

In this paper, we introduce a novel mobility model for mobile sinks in which the sinks move towards randomly distributed destinations, where each destination is associated with a mission. The novel mobility model is termed the random mobility with destinations. There have been many studies on mobile sinks; however, they merely support two extreme cases of sink mobility. The first case features the most common and general mobility, with the sinks moving randomly, unpredictably, and inartificially. The other case takes into account mobility only along predefined or determined paths such that the sinks can gather data from sensor nodes with minimum overhead. Unfortunately, these studies for the common mobility and predefined path mobility might not suit for supporting the random mobility with destinations. In order to support random mobility with destination, we propose a new protocol, in which the source nodes send their data to the next movement path of a mobile sink. To implement the proposed protocol, we first present a mechanism for predicting the next movement path of a mobile sink based on its previous movement path. With the information about predicted movement path included in a query packet, we further present a mechanism that source nodes send energy-efficiently their data along the next movement path before arriving of the mobile sink. Last, we present mechanisms for compensating the difference between the predicted movement path and the real movement path and for relaying the delayed data after arriving of the mobile sink on the next movement path, respectively. Simulation results show that the proposed protocol achieves better performance than the existing protocols.

• The Journal of the Acoustical Society of Korea
• /
• v.31 no.8
• /
• pp.542-550
• /
• 2012

In this paper, an adaptive scheme for network topology configuration is proposed to save the overall energy consumption in underwater acoustic sensor network. The proposed scheme employs a self-organized networking methodology where network topology is locally optimized by exchanging the energy-related information between neighboring nodes such as the remaining energy of each node, in a way that the network life time can be augmented without any centralized control function. Computer simulation is used to evaluate the proposed scheme comparing with LEACH in terms of the number of alive nodes after a given time, the deviation of individual nodes' residual energy and the energy consumption at the initialization and coordination stages.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.3
• /
• pp.251-260
• /
• 2011

In this paper, we proposed a scheme that it safely exchanges encrypted keys without Trust Third Party (TTP) and Pre-distributing keys in multi-hop clustering sensor networks. Existing research assume that it exists a TTP or already it was pre-distributed a encrypted key between nodes. However, existing methods are not sufficient for USN environment without infrastructure. Some existing studies using a random number Diffie-Hellman algorithm to solve the problem. but the method was vulnerable to Replay and Man-in-the-middle attack from the malicious nodes. Therefore, authentication problem between nodes is solved by adding a ��TESLA. In this paper, we propose a modified Diffie-Hellman algorithm that it is safe, lightweight, and robust pair-wise agreement algorithm by adding One Time Password (OTP) with timestamp. Lastly, authentication, confidentiality, integrity, non-impersonation, backward secrecy, and forward secrecy to verify that it is safe.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.3A
• /
• pp.304-310
• /
• 2006

This paper evaluates the performance of three types of data delivery mechanisms in clustered sensor networks, as a basic research to develop an energy efficient topology management scheme. In the first mechanism, one node per cluster(clusterhead) turns on its radio(or wakes up) to transmit and receive RTS/CTS/DATA/ACK messages, but in the second one, k nodes per cluster wake up and participate in the message exchange. In the last mechanism, clusterheads turn on the radio to exchange RTS/CTS messages, and if a clusterhead receives RTS containing its cluster m as a destination, it makes k nodes in the cluster hun on the radio to receive DATA and transmit ACK. Through simulation, we show the energy consumption of the three types of data delivery mechanisms as functions of the number of active nodes per cluster, offered load, and packet loss probability.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.8
• /
• pp.1505-1510
• /
• 2008

In large-scale wireless sensor networks, the deployed nodes cannot be replaced or recharged after first deployment. Also, dead nodes maγ lead to the partition of whole networks. While performing data dissemination under a battery power constraint, energy efficiency is a key design factor of routing protocol. As a solution for the efficient data dissemination, in this paper, we propose a protocol namely Hierarchical Data Dissemination (HDD) which provides scalable and efficient data delivery to multiple sources and mobile sinks. HDD uses the facts that sink nodes are central gathering Points and source-centric data forwarding paths are constructed and it is maintained with two-tier communications. The performance of HDD is compared with TTDD about the energy consumption, data delivery time and data success ration. The extensive simulation results show that HDD Routing Protocol outperforms TIDD by more than $1.5{\sim}3times$ on energy consumption.