• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.257-264
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• 2012

In this paper, we propose a Route Stability-based Direction Guided Routing protocol(RSDGR) in mobile ad-hoc wireless networks. The main features and contributions of the proposed routing protocol are as follows. First, it can calculate link stability between two nodes as well as route stability of multi hop quantitatively by using nodes' mobility. And this protocol can establish the most stable path between a source node and a destination node. Second, according to the route stability between a source node and a destination node, it can control and optimize the direction guided region dynamically for route setup. Third, we suggest theoretical model for quantitative calculation of link stability between two nodes and route stability of multi hop path. The performance evaluation of the proposed routing protocol is performed by simulation using OPNET(Optimized Network Engineering Tool) and theoretical analysis. The results of performance evaluation show that the patterns of PDR are similar in simulation and analysis according to route stability. The faster mobile nodes' velocity and the smaller source node's direct guided reigion, the lower route stability and PDR and the higher delay and control overhead related to this.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.5
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• pp.137-142
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• 2016

A two-step open system(TOS) was proposed to relay between a healing platform and a repository of personal health documents. TOS was designed by taking into consideration the pubsub service based on large scale connections to monitor a provider's access/request process for health documents in real time. TOS, however, uses WebSocket as a communication protocol in case of pubsub. Given the operational environment of low quality wireless networks for mobile devices that are user terminals in a healing platform, there is a need to add a messaging protocol to support QoS as well as a transmission protocol. As a light messaging protocol optimized for mobile devices, MQTT defines reliable messaging QoS to consider a wireless network situation of low speed/low quality. This study designed an MQTT protocol-based message broker to support QoS in case of large scale connections and pubsub by taking into consideration mobile devices that are user terminals in a healing platform. After designing a model between TOS and MQTT message broker, the study implemented a prototype based on the proposed design and compared it with its counterparts from previous studies based on the performance indicators in a load-test with the MQTT client tool.

• Journal of Advanced Navigation Technology
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• v.13 no.3
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• pp.327-336
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• 2009

This paper analysis the STDMA protocol in aviation wireless data communications and carry out the performance analysis with simulation. The STDMA protocol that is currently being used in VDL Mode-4 has TDMA system characteristics, which provides time-division into several slots per one frame. The results of modeled STDMA protocol's data channel analysis show approximate 0.7 channel throughput at the transmission probabilities 0.045, 0.2, and 0.3 in the aspects of channel throughput. The delay time are 2.32434sec, 2.0293sec, and 2.12128sec respectively. These results shows the good stability in spite of variable transmission probabilities. Consequently, it is expected that STDMA protocol would be used properly for domestic communication demands and supervision system improvement by means of applying this to point-to-point communication and data/location broadcasting as a fundamental technology in CNS/ATM.

• 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.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.5
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• pp.1-6
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• 2009

MANET(Mobile Ad-hoc NETwork), a network characterized that its moving nodes freely constructs Network topology, has other different characteristics. Because Policy based Network Management in MANET guarantees QoS between nodes, it is essential in applied areas like VANET which targets safety and convenience. In this paper, we use COPS-PR which is appropriate Policy Exchange Protocol for MANET, and implement DiffServ-based QoS in the real networks and experiment its capability.

• Journal of Korea Multimedia Society
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• v.10 no.12
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• pp.1645-1654
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• 2007

In this paper, we study the problem of load balancing routing in clustered-based wireless mesh network in order to enhance the overall network throughput. We first address the problems of cluster allocation in wireless mesh network to achieve load-balancing state. Due to the complexity of the problem, we proposed a simplified algorithm using gradient load-balancing model. This method searches for a localized optimal solution of cluster allocation instead of solving the optimal solution for overall network. To support for load-balancing algorithm and reduce complexity of topology control, we also introduce limited broadcasting between two clusters. This mechanism maintain shortest path between two nodes in adjacent clusters while minimizing the topology broadcasting complexity. The simulation experiments demonstrate that our proposed model achieve performance improvement in terms of network throughput in comparison with other clustering methods.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.93-99
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• 2013

The proposed protocol is to get better performance compared to the existing method, also it can save the node number. There is needed a lot of secondary user for cooperative spectrum detection in Rayleigh fading channel. In this proposal, we suggest the new cooperative spectrum detector which can choose one secondary user with high power, while other SUs can be used as relays.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.121-129
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• 2010

In this paper, we analyze effects of positions of relays on the performance of cooperative communication networks. From this, the best relays are chosen to assist transmitting the signal to the destination or to replace the source to retransmit the signal to the destination whenever the destination incorrectly receives the signal from the source. As the results, we show the significant improvement on performance of schemes choosing best relays, which is compared to the performance of other cooperative schemes. Moreover, the simulation results that match exactly with the theoretical results prove the correctness of the analysis.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.1
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• pp.23-29
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• 2015

Energy constraints of wireless sensor networks are an important challenge. Data Transmission requires energy. Distance between origin and destination has an important role in energy consumption. In addition, the location of base station has a large impact on energy consumption and a specific method not proposed for it. In addition, a obtain model for location of base station proposed. Also a model for distributed clustering is presented by cluster heads. Eventually, a combination of discussed ideas is proposed to improve the energy consumption. The proposed ideas have been implemented over the LEACH-C protocol. Evaluation results show that the proposed methods have a better performance in energy consumption and lifetime of the network in comparison with similar methods.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.125-128
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• 2008

In this paper, the Transport Protocol Experts Group(TPEG) transmission and reception system based on Digital Radio Mondiale(DRM) is implemented for traffic information services. DRM stands for the European radio broadcasting standard to bring AM radio into digital radio, designed to work at frequencies below 30MHz. DRM can offer various data services such as text messages and a slide show service as well as audio services. In spite of low datarate, the TPEG system on DRM has an advantage that the traffic information service system for whole country can be established because DRM can offer wider service ranges than terrestrial-digital multimedia broadcasting(T-DMB) and simply archive a single frequency network.