• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.175-176
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• 2007

In this paper, we introduce Satellite Digital Multimedia Broadcasting(S-DMB) system and show the method increasing the channel capacity. To reduce the burden that has to change the existing system, the system has to be offered the Backward-compatibility. This paper show the method using hierarchical 16APSK modulation. And to obtain the reasonable BER performance between existing path(we call high priority) and additional path(we call low priority).

• Journal of Communications and Networks
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• v.12 no.6
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• pp.568-576
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• 2010

The paper presents a control architecture aimed at implementing bandwidth optimization combined with call admission control (CAC) over a digital video broadcasting (DVB) return channel satellite terminal (RCST) under quality of service (QoS) constraints. The approach can be applied in all cases where traffic flows, coming from a terrestrial portion of the network, are merged together within a single DVB flow, which is then forwarded over the satellite channel. The paper introduces the architecture of data and control plane of the RCST at layer 2. The data plane is composed of a set of traffic buffers served with a given bandwidth. The control plane proposed in this paper includes a layer 2 resource manager (L2RM), which is structured into decision makers (DM), one for each traffic buffer of the data plane. Each DM contains a virtual queue, which exactly duplicates the corresponding traffic buffer and performs the actions to compute the minimum bandwidth need to assure the QoS constraints. After computing the minimum bandwidth through a given algorithm (in this view the paper reports some schemes taken in the literature which may be applied), each DM communicates this bandwidth value to the L2RM, which allocates bandwidth to traffic buffers at the data plane. Real bandwidth allocations are driven by the information provided by the DMs. Bandwidth control is linked to a CAC scheme, which uses current bandwidth allocations and peak bandwidth of the call entering the network to decide admission. The performance evaluation is dedicated to show the efficiency of the proposed combined bandwidth allocation and CAC.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.107-112
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• 2015

A smart phone and the number of wireless terminals are mobile-to the nature of the AP mobility are many call transfer between wireless terminals and AP (Access Point). Each wireless terminal that is the call processing process for each is relatively large to cause the wireless traffic, and a factor that inhibits the efficient use of the radio band on the AP. In this paper, we use the power intensity threshold and threshold timer of the AP received by the mobile station to reduce the amount of switching traffic between the AP's cause and traffic generation factors between the wireless device and the AP that can effectively utilize the radio traffic from the AP the measures proposed. The proposed method and the conventional method is improved by simulation to handle the amount of radio traffic from the AP it was confirmed that it is possible to effectively utilize the whole of the radio band.

• Journal of Advanced Navigation Technology
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• v.13 no.2
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• pp.208-213
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• 2009

This paper presents an adaptive call admission control(CAC) algorithm based on a target handoff call dropping probability in mobile wireless environments. This method uses a neural network for predicting and reserving the bandwidth demands for handoff calls and new calls. The amount of bandwidth to be reserved is adaptively adjusted by a target value of handoff call dropping probability(CDP). That is, if the handoff CDP exceeds the a target CDP value, the bandwidth to be reserved should be increased to reduce the handoff dropping probability below a target value. The proposed method is intended to prevent from increasing handoff call dropping probability when bandwidth to be reserved is not enough for handoff calls due to an uncertain prediction. Our simulations compare the handoff CDP in proposed CAC with that of an existing CAC. Results show that the proposed method sustains handoff call dropping probability below our target value.

• International journal of advanced smart convergence
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• v.8 no.3
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• pp.69-77
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• 2019

Today, most of elevators have an emergency call facility for emergency situations. However, if the network installed in the elevator is also out of power, it cannot be used for the elevator remote monitoring and management. So, we develop an integrated and unified emergency call system, which can transmit not only telephone call but also data signals using PSTN(Public Switched Telephone Network) in order to remote monitoring and management of elevators, even though a power outage occurs. The proposed integrated emergency call system to process multiple data such as voice and operational information is a multi-channel board system which is composed of an emergency phone signal processing module and an operational information processing module in the control box of elevator. In addition, the RMS(remote management server) systems based on the Web consist of a dial-up server and a remote monitoring server where manages the elevator's operating information, status records, and operational faults received via the proposed integrated and unified emergency call system in real time. So even if there's a catastrophic emergency, the proposed RMS systems shall ensure and maintain the safety of passengers inside the elevator. Also, remote control of the elevator by this system should be more efficient and secure. In near future, all elevator emergency call system need to support multifunctional capabilities to transmit operational data as well as phone calls for the safety of passengers. In addition, for safer elevators, it is necessary to improve them more efficiently by combining them with high-tech technologies such as the Internet of Things and artificial intelligence.

• The Journal of Information Systems
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• v.8 no.1
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• pp.109-129
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• 1999

This study deals with the problem of information dissemination in a communication network, which is defined to be the process whereby a set of messages, generated by an originator, is transmitted to all the members within the network. Since this type of message generally includes control data to manage the network or global information that all members should know, it is to be required to transmit it to all the members as soon as possible. In this study, it is assumed that a member can either transmit or receive a message and an informed member can transmit it to only one of its neighbors at time. This type of transmission is called 'local broadcasting' Several schemes of call sequencing are designed for a general-type network with nonuniform edge transmission times, and then computer simulations are performed. Some heuristics for information dissemination are proposed and tested. For this, optimal call sequence in a tree-type network, sequencing theory and graph theory are applied. The result shows that call sequencing based on the shortest path tree is the most desirable.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.2
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• pp.61-66
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• 2020

The purpose of this study is to identify and manage the problem of components discontinuity in the future based on the implementation of information systems to solve the problem of discontinuance of militaries parts, so as to solve the problem of discontinuance of components in the operation of the weapon systems and reduce excessive expenditure due to aging of the weapon system. The purpose is to prevent the discontinuance of components in the future by up-dating the production phenomena of parts manufactures periodically. Defense industries and R&D perood can expand users convenience by supporting selection of more efficient parts in weapon systems development and information of vast components information systems.

• Journal of the Korea Convergence Society
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• v.10 no.8
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• pp.9-14
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• 2019

Currently, with the success of 5G commercialization, a server system that integrates various Internet public safety services should be developed. In this paper, we developed a public safety integrated server, which is an IoT platform connecting IoT device and IoT gateway based on IP PBX. This server is based on embedded OS and various IoT services are executed in one system and call processing / broadcasting server function that processes emergency call and emergency broadcasting in public places is built in. This system collects IoT sensor data and emergency bell information and automatically sends out emergency alarms, emergency evacuation broadcasts, etc. at an accident site in an emergency situation, and transmits the daily information to the upper IoT service server, Provide public safety management services.

• Journal of Advanced Navigation Technology
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• v.12 no.1
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• pp.22-27
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• 2008

This paper presents adaptive-MMOSPRED method for prediction of resource demands requested by multimedia calls, and shows the performance of the call admission control based on proposed resource prediction method in multimedia wireless networks. The proposed method determines (I-CDP) random variables of the standard normal distribution by using LMS algorithm that minimize errors of prediction in resource demands, while parameters in an existing method are constant all through the prediction time. Our simulation results show that prediction error in adaptive-MMOSPRED method is much smaller than in fixed-MMOSPRED method. Also we can see via simulation the CAC performance based on the proposed method improves the new call blocking performance compared with the existing method under the desired handoff dropping probability.

• International journal of advanced smart convergence
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• v.1 no.1
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• pp.19-26
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• 2012

The deployment of mobile femtocellular networks can enhance the service quality for the users inside the vehicles. The deployment of mobile femtocells generates a lot of handover calls. Also, numbers of group handover scenarios are found in mobile femtocellular network deployment. The ability to seamlessly switch between the femtocells and the macrocell networks is a key concern for femtocell network deployment. However, until now there is no effective and complete handover scheme for the mobile femtocell network deployment. Also handover between the backhaul networks is a major concern for the mobile femtocellular network deployment. In this paper, we propose handover control between the access networks for the individual handover cases. Call flows for the handover between the backhaul networks of the macrocell-to-macrocell case are proposed in this paper. We also propose the link switching for the FSO based backhaul networks. The proposed resource allocation scheme ensures the negligible handover call dropping probability as well as higher bandwidth utilization.