• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.754-762
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• 2021

Seamless wireless communication network access technology enables users to guarantee service continuity. Hence, it is necessary for disaster situations in which network service may be interrupted. The Multi-path router is a technology to improve network stability and strengthen field operability, particularly in a disaster environment where network failure can occur by providing high-performance data transmission using multi-communication networks and network security by VPN-based wireless IP. In this paper, a prototype system for an MPR-based wireless communication network was proposed to improve the operation performance for disaster field investigation applications. A comparative experiment was performed on various data transmission performances with the existing single wireless communication network. In addition, another experiment was conducted by measuring the data packet transmission and receiving performance in the existing/new wireless communication system first and then assessing the UDP transmission performance in a single router environment to understand the transmission capability of the new MPR. The experimental results showed that the sending and receiving performance was improved by approximately double that of the existing single wireless communication system. The proposed prototype system is expected to allow users to share and disseminate collected on-site data more quickly and efficiently during a disaster site investigation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4044-4062
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• 2016

We investigate the optimization of energy consumption in Mobile Cloud environment in this paper. In order to optimize the energy consumed by the CPUs in mobile devices, we put forward using the asymptotic time complexity (ATC) method to distinguish the computational complexities of the applications when they are executed in mobile devices. We propose a multi-scale scheme to quantize the channel gain and provide an improved dynamic transmission scheduling algorithm when offloading the applications to the cloud center, which has been proved to be helpful for reducing the mobile devices energy consumption. We give the energy estimation methods in both mobile execution model and cloud execution model. The numerical results suggest that energy consumed by the mobile devices can be remarkably saved with our proposed multi-scale scheme. Moreover, the results can be used as a guideline for the mobile devices to choose whether executing the application locally or offloading it to the cloud center.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.1180-1197
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• 2013

Network coding is one of the most promising techniques to increase the reliability and reduce the energy consumption for wireless sensor networks (WSNs). However, most of the previous works mainly focus on the network coding for multicast or unicast in WSNs, in spite of the fact that the converge-cast is the most common communication style in WSNs. In this paper, we investigate, for the first time as far as we know, the feasibility of acquiring network coding benefits in converge-cast, and we present that with the ubiquitous convergent structures self-organized during converge-casting in the network, the reliability benefits can be obtained by applying linear network coding. We theoretically derive the network coding benefits obtained in a general convergent structure, and simulations are conducted to validate our theoretical analysis. The results reveal that the network coding can improve the network reliability considerably, and hence reduce number of retransmissions and improve energy-efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.1077-1093
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• 2013

This paper proposes a new network coordinator node design to select the most suitable wireless technology for WBANs by using fuzzy logic. Its goal is to select a wireless communication technology available considering the user/application requirements and network conditions. A WBAN is composed of a set of sensors placed in, on, or around human body, which monitors the human body functions and the surrounding environment. In an effort to send sensor readings from human body to medical center or a station, a WBAN needs to stay connected to a local or a wide area network by using various wireless communication technologies. Nowadays, several wireless networking technologies may be utilized in WLANs and/or WANs each of which is capable of sending WBAN sensor readings to the desired destination. Therefore, choosing the best serving wireless communications technology has critical importance to provide quality of service support and cost efficient connections for WBAN users. In this work, we have developed, modeled, and simulated some networking scenarios utilizing our fuzzy logic-based NCN by using OPNET and MATLAB. Besides, we have compared our proposed fuzzy logic based algorithm with widely used RSSI-based AP selection algorithm. The results obtained from the simulations show that the proposed approach provides appropriate outcomes for both the WBAN users and the overall network.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1873-1878
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• 2017

Recently, many researches have been conducted on the aviation industry to replace the wire harness cable between the avionics of the aircraft with the wireless network. In this paper, we present an Event-Based Simulator for Wireless Avionics Intra-Communications (ES-WAIC) that can verify core technologies of wireless networks and efficiently integrate different layers of the network. ES-WAIC is developed to enhance the readability between the real time control application developers of the higher layer and the network layer developers. Specifically, the practical implement relies on an event-based programming concept to increase portability and compatibility that can be applied to the realistic low-power wireless embedded networks. ES-WAIC implements the overall system layers including the wireless channel modeling of the 4.4GHz band, the physical layer, the medium access control, the network, and the application layer of wireless avionics intra-communications.

• Journal of Korea Multimedia Society
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• v.21 no.5
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• pp.592-598
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• 2018

In wireless sensor networks where there is no centralized base station, each node has limited transmission range and the multi-hop routing for transmitting data to the destination is the one of the important technical issues. In particular, the wireless sensor network is not powered by external power source but operates by its own battery, so it is required to maximize the network life through efficient use of energy. To balance the power consumption, the residual power based adaptive power control is required in routing protocol. In this paper, we propose a routing protocol that prolongs the network lifetime by balancing the power consumption among the nodes by controlling the transmit power according to the residual power. We evaluate the proposed routing protocol using extensive simulation, and the results show that the proposed routing scheme can balance the power consumption and prolong network lifetime.

• Journal of the Society of Disaster Information
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• v.1 no.1
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• pp.91-119
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• 2005

When the national disaster accident is occurred, it is difficult to maintain the mutual cooperation systems. In order to solve the problems, the construction of the national unified command wireless network is necessary. In this paper, the specified state of the characteristic frequency of the digital TRS wireless network constructed recently is investigated and analyzed. Through the analysis, the problems of the construction of the national unified command wireless network are grasped. To solve the problem, it is proposed that the digital TRS wireless network is connected with the satellite communication network, and connected with the existing wireless network, LMR. In the concretely it is proposed that the natural unified wireless network should be proceeded step by step. At first, for 2 years the existing networks of the Fire Fighting Agency, the Police, the Forest Service and so on must be utilized and prepared to link with TRS. The second, for 2 years it is carried forward a scheme to maintain the properties of the agencies concerned. Further, it must be prepared to connect with satellite network. At third, for 2 years all agencies concerned with the fire fighting and the disaster prevention must be unified, and the systems have to be promoted for the p1an of linkage of TRS network and the existing network. Next the agencies concerned have to be unified and the authority has to be intensified. When a disaster is occurred, the National Emergency Management Agency has to play a central role. In a local area it has to be given the Fire Fighting Agency an authority and a duty to get ready for each emergency situation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.6
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• pp.2680-2696
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• 2018

The collaborative content caching system is an effective solution developed in recent years to reduce transmission delay and network traffic. In order to decrease the service end-to-end transmission delay for future 5G ultra-dense networks (UDN), this paper proposes a novel service migration method that can guarantee the continuity of service and simultaneously reduce the traffic flow in the network. In this paper, we propose a service migration optimization model that minimizes the cumulative transmission delay within the constraints of quality of service (QoS) guarantee and network condition. Subsequently, we propose an improved firefly algorithm to solve this optimization problem. Simulation results show that compared to traditional collaborative content caching schemes, the proposed algorithm can significantly decrease transmission delay and network traffic flow.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.1
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• pp.87-94
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• 2019

A wireless sensor network is emerging technology and intelligent wireless communication paradigm that is dynamically aware of its surrounding environment. It is also able to respond to it in order to achieve reliable and efficient communication. The dynamical cognition capability and environmental adaptability rely on organizing dynamical networks effectively. However, optimally clustering the cognitive wireless sensor networks is an NP-complete problem. The objective of this paper is to develop an optimal sensor network design for maximizing the performance. This proposed Ranking Artificial Bee Colony (RABC) is developed based on Artificial Bee Colony (ABC) with ranking strategy. The ranking strategy can make the much better solutions by combining the best solutions so far and add these solutions in the solution population when applying ABC. RABC is designed to adapt to topological changes to any network graph in a time. We can minimize the total energy dissipation of sensors to prolong the lifetime of a network to balance the energy consumption of all nodes with robust optimal solution. Simulation results show that the performance of our proposed RABC is better than those of previous methods (LEACH, LEACH-C, and etc.) in wireless sensor networks. Our proposed method is the best for the 100 node-network example when the Sink node is centrally located.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.6
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• pp.43-48
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• 2009

Wireless mesh networks, unlike Ad-hoc network, has low mobility and multi-path communication between terminals and other networks because it has the backbone structures. Most studies are advanced on finding the optimal routing path in multi-hop wireless mesh network environment. Various routing metric, minimum number of hops(Hop_count) and ETX, ETT metric, are proposed to wireless mesh networks. However, most metrics cannot identify the high throughput routing paths because this metric uses a different measurement parameters in each direction. So actual delivery rate does not provide to this metric. This paper describes the metric and implementation of IETC as a metric. This paper shows the improvement in performance.