• IEMEK Journal of Embedded Systems and Applications
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• v.8 no.2
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• pp.69-78
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• 2013

As vehicles become more intelligent for safety and convenience of drivers, in-vehicle networking systems such as controller are network (CAN) have been widely used due to increasing number of electronic control unit (ECU). Recently, FlexRay was developed to replace CAN protocol in chassis networking systems, to remedy the shortage of transmission capacity and unsatisfactory real-time transmission delay of conventional CAN. However, it is difficult for vehicle network designers to calculate platform configuration registers (PCR) and determine a base cycle or slot length of FlexRay. To assist vehicle network designers for designing FlexRay cluster, this paper presents automatic field bus exchange format (FIBEX) generation algorithm from CANdb information, which is de-facto standard database format for CAN. To design this program, structures of FIBEX, CANdb and relationship among PCR variables are analyzed.

• Journal of Sensor Science and Technology
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• v.18 no.6
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• pp.409-416
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• 2009

A lot of valuable-piece of information are acquisited through ubiquitous sensor network(USN) system composed of man-made sensors. The telemetry system used for communicating to access informations between nature and human-beings monitors and estimates the status of infrastructure, utilities and natural environments to prevent hidden disasters, improving quality of life and productivity in multi-directional views. That would be the reason of USN subsistence. This paper will be a review on how to build long-term USN system. Therefore, this paper focuses on reviewing the sensor interface and the sensor network interface and its significance as the foundation stone for varying USN service profiles and showing its development example, and finally proposing a few of things to set up future-oriented USN open system.

• Journal of Information Processing Systems
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• v.11 no.4
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• pp.616-629
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• 2015

A mobile terminal will expect a number of handoffs within its call duration. In the event of a mobile call, when a mobile node moves from one cell to another, it should connect to another access point within its range. In case there is a lack of support of its own network, it must changeover to another base station. In the event of moving on to another network, quality of service parameters need to be considered. In our study we have used the Markov decision process approach for a seamless handoff as it gives the optimum results for selecting a network when compared to other multiple attribute decision making processes. We have used the network cost function for selecting the network for handoff and the connection reward function, which is based on the values of the quality of service parameters. We have also examined the constant bit rate and transmission control protocol packet delivery ratio. We used the policy iteration algorithm for determining the optimal policy. Our enhanced handoff algorithm outperforms other previous multiple attribute decision making methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1498-1505
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• 2009

In centralized control sensor network, tree-based multi-channel communication overcomes the recurrent channel switching and makes possible to transfer data simultaneously from different sources. In our paper, we propose a greedy algorithm named as NIT (Non-Intersecting Tree) that the trees can avoid inter-tree interference. We also propose channel switching technique by which trees can avoid link failure or area blocking due to external interference locally without rerunningthe algorithm and without interrupting the whole network. At first we applied our algorithm for a random topology and then we evaluate the performance of the network using NS-2 simulator. The results show that with the increasing of channel the throughputand delivery ratio are increased significantly. We got better performance than a using a recent proposed Tree-based Multi-Channel Protocol (TMCP).

• Journal of IKEEE
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• v.23 no.3
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• pp.1096-1099
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• 2019

In this paper, we propose the protocol for construction of smart factory. The proposed protocol for construction of smart factory consists of an OPC UA Server/Client, a technology of TSN realtime communication, a NTP & PTP time synchronization protocol, a FieldBus protocol and conversion module, a technology of saving data for data transmit latency and synchronization protocol. OPC UA server/client is a system integration protocol which makes interface industrial hardware device and supports standardization which allows in all around area and also in not independent from any platform. A technology of TSN realtime communication provides an high sensitive time management and control technology in a way of sharing specific time between devices in the field of high speed network. NTP & PTP time synchronization protocol supports IEEE1588 standardization. A fieldbus protocol and conversion module provide an extendable connectivity by converting industrial protocol to OPC. A technology of saving data for data transmit latency and synchronization protocol provide a resolution function for a loss and latency of data. Results from testing agencies to assess the performance of proposed protocol for construction of smart factory, response time was 0.1367ms, synchronization time was 0.404ms, quantity of concurrent access was 100ea, quantity of interacting protocol was 5ea, data saving and synchronization was 1,000 nodes. It produced the same result as the world's highest level.

• ETRI Journal
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• v.34 no.6
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• pp.827-837
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• 2012

We propose a flow admission control (FAC) for setting up a wire-speed connection for new flows based on their negotiated bandwidth. It also terminates a flow that does not have a packet transmitted within a certain period determined by the users. The FAC can be used to provide a reliable transmission of user datagram and transmission control protocol applications. If the period of flows can be set to a short time period, we can monitor active flows that carry a packet over networks during the flow period. Such powerful flow management can also be applied to security systems to detect a denial-of-service attack. We implement a network processor called a flow management network processor (FMNP), which is the second generation of the device that supports FAC. It has forty reduced instruction set computer core processors optimized for packet processing. It is fabricated in 65-nm CMOS technology and has a 40-Gbps process performance. We prove that a flow router equipped with an FMNP is better than legacy systems in terms of throughput and packet loss.

• The Journal of the Korea Contents Association
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• v.8 no.1
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• pp.177-185
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• 2008

Research on media access control (MAC) scheme for Wireless Sensor Network (WSN) has been mainly focused on energy efficiency improvement, while interest on latency is relatively weak. However, end-to-end latency could be a critical limitation specifically in the multi-hop network such as wireless multimedia sensor networks. In this paper we propose a media access control scheme with distributed transmission power control to Improve end-to-end transmission latency as well as reduce power consumption in multi-hop wireless sensor networks. According to the simulation results, the proposed scheme is turned out to be an energy efficient scheme with improved end-to-end transmission latency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.18-25
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• 2020

With the development of water internet technology, data communication between objects is expanding. Research related to data communication technology between vehicles that incorporates related technologies into vehicles has been actively conducted. For data communication between mobile terminals, data stability, reliability, and real-time performance must be guaranteed. The 5 GHz Wi-Fi band, which is advantageous in bandwidth, communications speed, and wireless saturation of the wireless network, was selected as the data communications network between vehicles. This study analyzes how to design and implement a 5 GHz Wi-Fi network in a vehicle network. Considering the characteristics of the mobile communication terminal device, a continuous variable communications structure is proposed to enable high-speed data switching. We simplify the access point access procedure to reduce the latency between wireless terminals. By limiting the Transmission Control Protocol Internet Protocol (TCP/IP)-based Dynamic Host Configuration Protocol (DHCP) server function and implementing it in a broadcast transmission protocol method, communication delay between terminal devices is improved. Compared to the general commercial Wi-Fi communication method, the connection operation and response speed have been improved by five seconds or more. Utilizing this method can be applied to various types of event data communication between vehicles. It can also be extended to wireless data-based intelligent road networks and systems for autonomous driving.

• Journal of Advanced Navigation Technology
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• v.15 no.1
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• pp.54-60
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• 2011

The development of wireless sensor networks (WSN) can be motivated by several types of applications. However, these applications demand an energy-efficient WSN that can prolong the network lifetime and can provide high throughput, low latency and delay. Designing wireless sensor networks with the capability of prolonging network lifetime catch the attention of many researchers in wireless system and network field. Contrasts with Mobile Ad Hoc Network system, Wireless Sensor Networks designs focused more on survivability of each node in the network instead of maximizing data throughput or minimizing end-to-end delay. In this paper, we will study part of data link layer in Open Systems Interconnection (OSI) model, called medium access control (MAC) layer. Since the MAC development of energy aware MAC Protocol for wireless sensor layer controls the physical radio part, it has a large impact on the overall energy consumption and the lifetime of a node. This paper proposes a analytical approach that tries to reduce idle energy consumption, and shows the increasement of network end-to-end arrival rate due to efficiency in energy consumption from time slot management.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10B
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• pp.899-915
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• 2003

Delivering rich and continuous media contents robustly over a wide range of network conditions of the wired/wireless Internet is a highly challenging task. To address this challenges, the continuous media applications at the edge of network has become more and more adaptive while the best-effort Internet is slowly progressing towards improved networking services. That is, the role of network adaptive media delivery, which dynamically links the quality demand of application contents to the underlying networking services, has become more crucial. In this paper, we will first review the required network adaptation functionalities seen from the application side: congestion control / rate control, error control, and synchronization / adaptive playout. Then, we start the coverage of networking support issues that helps the realization of network adaptive media streaming - from network support and protocol support toward consolidated support via middleware. Finally, we propose a dynamic network adaptation framework that efficiently leverages its awareness of both media application (including contents) and underlying networking support.