• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.81-88
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• 2012

As the performance of the next-generation broadband wireless networks is dramatically enhanced, various services (i.e., education, Live video streaming, Live video conferencing, online games, etc.) have been provided to users through a smart mobile platform. Those services are usually provided by using the centralized communication server. However, since all multimedia traffic is exchanged through a communication server, it often has the scalability problem with regard to traffic management. Our main purpose is for group smart users to provide scalable live multimedia streaming service based on P2P network. To do this, we have designed an architecture of P2P-based service management for mobile group communication management and service management protocol. In order to verify the performance of the proposed scheme, we have mathematically analyzed the performance in terms of the average transmission delay and bandwid th utilization.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1204-1227
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• 2020

The tradeoff between energy conservation and traffic balancing is a dilemma problem in Wireless Sensor Networks (WSNs). By analyzing the intrinsic relationship between cluster properties and long distance transmission energy consumption, we characterize three node sets of the cluster as a theoretical foundation to enhance high performance of WSNs, and propose optimal solutions by introducing rendezvous and Mobile Elements (MEs) to optimize energy consumption for prolonging the lifetime of WSNs. First, we exploit an approximate method based on the transmission distance from the different node to an ME to select suboptimal Rendezvous Point (RP) on the trajectory for ME to collect data. Then, we define data transmission routing sequence and model rendezvous planning for the cluster. In order to achieve optimization of energy consumption, we specifically apply the economic theory called Diminishing Marginal Utility Rule (DMUR) and create the utility function with regard to energy to develop an adaptive energy consumption optimization framework to achieve energy efficiency for data collection. At last, Rendezvous Transmission Algorithm (RTA) is proposed to better tradeoff between energy conservation and traffic balancing. Furthermore, via collaborations among multiple MEs, we design Two-Orbit Back-Propagation Algorithm (TOBPA) which concurrently handles load imbalance phenomenon to improve the efficiency of data collection. The simulation results show that our solutions can improve energy efficiency of the whole network and reduce the energy consumption of sensor nodes, which in turn prolong the lifetime of WSNs.

• Journal of the Institute of Convergence Signal Processing
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• v.15 no.2
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• pp.64-69
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• 2014

Ultrasound system is one of the complex wireless signal processing systems that are widely used in the fields of modern industry such as medical diagnostics, underwater communications, and sensor-networks. Miniaturization of ultrasound system has been raging recently. In this paper, a hybrid LNA that is suitable for miniaturization and mobile diagnostic ultrasound system has been developed. The proposed LNA has low noise figure of less than 5dB, and the feedback resistor is designed to be electrically adjusted in order to attain the impedance-matching for various ultrasound transducers. It supports the whole ultrasound frequencies from 10KHz to 150MHz frequency band and also provides sleep modes. A gain from -18.8 to -29.5 dB is achieved by adjusting each transducer to fit the system character. Power consumption can be reduced up to 90% in similar performance as compared to the existing LNA.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.3
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• pp.181-185
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• 2009

Recently, much attention to a self-organizing mobile ad-hoc network is escalating along with progressive deployment of wireless networks in our everyday life. Being readily deployable, the MANET (mobile ad hoc network) can find its applications to emergency medical service, customized calling service, group-based communications, and military purposes. In this paper we investigate a time slot exchange problem found in the time slot based MAC, that is designed for IEEE 802.11b interfaces composing a MANET. The paper provides a method to maintain the quality of voice call by providing a new time slot when the channel assigned for that time slot gets noisy with interferences induced from other nodes, which belong to the same and/or other subgroups. In order to assess the performance of the proposed algorithm, a set of simulations using the OPNET modeler has been performed assuming that the IEEE 802.11b interfaces are operating under a modified MAC, which is a time slot based reservation MAC implemented in the PCF part of the superframe. In a real-time voice call service over a MANET of a size 500 ${\times}$ 500 meter squares with the number of nodes up to 100, the simulation results are collected and analyzed with respect to the packet loss rate and packet delay. The results show us that the proposed time slot exchange protocol improves the quality of voice call over that of plain DCF.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.5
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• pp.107-119
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• 2013

This paper reinforced security under the network evaluation of wire wireless integration of NEMO (NEwork MObility) supporting mobility and network-based PMIPv6 (Proxy Mobile IPv6). It also proposes $SK-L^2AS$ (Symmetric Key-Based Local-Lighted Authentication Scheme) based on simple key which reduces code calculation and authentication delay costs. Moreover, fast handover technique was also adopted to reduce handover delay time in PMIPv6 and X-FPMIPv6 (eXtension of Fast Handover for PMIPv6) was used to support global mobility. In addition, AX-FPMIPv6 (Authentication eXtension of Fast Handover for PMIPv6) is proposed which integrated $SK-L^2AS$ and X-FPMIPv6 by applying Piggybacks method to reduce the overhead of authentication and signaling. The AX-FPMIPv6 technique suggested in this paper shows that this technique is better than the existing schemes in authentication and handover delay according to the performance analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7A
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• pp.540-547
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• 2009

In this paper, we work for the efficient use of the initial ranging contention slot in OFDMA based wireless mobile networks. Specially, the collision reduction method using an automatic adaptive optimal algorithm is studied for initial ranging contention slot used at initial connection of the mobile terminals. As a result, we propose the algorithm that achieves the collision minimization and the auto-dynamic slot arrangement of the initial ranging slots. To evaluate the proposed algorithm, we compare the simulation results of IEEE802.16e fixed initial ranging slot allocation method versus the proposed algorithm. The simulator is developed based on the IEEE802.16e standard MAC frame structure and processing procedures. As the simulation results, we can expect the proposed algorithm can be applied for the unmanned coastal base station because the proposed algorithm has the effect of minimizing administration cost for the base station.

• Journal of KIISE:Information Networking
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• v.36 no.5
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• pp.405-412
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• 2009

Mobile ad hoc networks (MANETs) allow mobile nodes to communicate among themselves via wireless multiple hops without the help of the wired infrastructure. In the MANET, it is required not only a route setup mechanism that makes nodes not within each other's transmission range communicate but also mechanism in order for a node to auto-configure a unique address. In this paper, we propose an address auto-configuration mechanism when MANET is connected to the Internet via several Internet Gateways and all gateways advertise the same network prefix. By using the proposed mechanism, once a node configures an Internet topologically correct and globally unique IP address, then the node can utilize the configured address even though the node moves within the MANET. Through the simulations, we analyze the performance of our proposed mechanism and, from the simulation results, we show that out proposed mechanism outperforms the existing mechanism.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1214-1221
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• 2007

Ad-hoc network is soft wireless communication network that is consisted of mobile node and clusters without helping of infrastructure. We propose a new ad hoc multicast routing protocol for based on the ontology scheme called inference network. Ontology knowledge-based is one of the structure of context-aware. Proposed structure is consisted of context awareness parameters as like distance between each nodes. The proposed architecture performs two types of routing discovery. One is Flooding Discovery Routing(FDR) for comparing analysis step and Local Discovery Routing(LDR) to compose path of node forecast(preservation) step from node's state value. The inference network structure of proposed RODMRP(Resilient Ontology-based Dynamic Multicast Routing Protocol) adopts a tree structure to enhance an efficient packet in various environment between mobile node. We will have developed an algorithm that will desist multi-hierarchy Layered networks to simulate a desired system.

• Smart Media Journal
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• v.8 no.3
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• pp.88-94
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• 2019

Livestock disease is a very important issue in the livestock industry because if livestock disease is not responded quickly enough, its damage can be devastating. To solve the issues involving the occurrence of livestock disease, it is necessary to diagnose in advance the status of livestock disease and develop systematic and scientific livestock feeding technologies. However, there is a lack of domestic studies on such technologies in Korea. This paper, therefore, proposes Livestock Disease Forecasting and Livestock Farm Integrated Control System using Cloud Computing to quickly manage livestock disease. The proposed system collects a variety of livestock data from wireless sensor networks and application. Moreover, it saves and manages the data with the use of the column-oriented database Hadoop HBase, a column-oriented database management system. This provides livestock disease forecasting and livestock farm integrated controlling service through MapReduce Model-based parallel data processing. Lastly, it also provides REST-based web service so that users can receive the service on various platforms, such as PCs or mobile devices.

• International journal of advanced smart convergence
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• v.8 no.2
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• pp.109-115
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• 2019

Currently, LPWA(Low Power Wide Area) communication technology is widely used due to the development of IoT(Internet of Things) technology. Among the LPWA technologies, LoRaWAN(Long Range Wide Area Network) is widely used in many fields due to its wide coverage, stable communication speed, and low-cost modem module prices. In particular, LoRa(Long Range) can easily construct LoRaWAN with a dedicated gateway. So many organizations are building their own LoRaWAN-based networks. The LoRaWAN Gateway receives the LoRa packet transmitted from an End-device installed in the adjacent location, converts it into the Internet protocol, and sends the packet to the final destination server. Current LoRa Gateway uses a single-hop method, and each gateway must include a communication network capable of the Internet. If it is the mobile communication(i.e., WCDMA, LTE, etc.) network, it is required to pay the internet usage fee which is installed in each gateway. If the LoRa communication is frequent, the user has to spend a lot of money. We propose an idea on how to design a multi-hop protocol which enables packet routing between gateways by analyzing the LoRaWAN communication method implemented in its existing single-hop way in this paper. For this purpose, this paper provides an analysis of the standard specification of LoRaWAN and explains what was considered when such protocol was designed. In this paper, two gateways have been placed based on the functional role so as to make the multi-hop protocol realized: (i) hopping gateway which receives packets from the end-device and forwards them to another gateway; and (ii) main gateway which finally transmits packets forwarded from the hopping gateway to the server via internet. Moreover, taking into account that LoRaWAN is wireless mobile communication, a level-based routing method is also included. If the protocol proposed by this paper is applied to the LoRaWAN network, the monthly internet fee incurred for the gateway will be reduced and the reliability of data transmission will be increased.