• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3711-3730
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• 2014

Cognitive radio networks (CRNs) have emerged as a promising solution to enhance spectrum utilization by using unused or less used spectrum in radio environments. The basic idea of CRNs is to allow secondary users (SUs) access to licensed spectrum, under the condition that the interference perceived by the primary users (PUs) is minimal. In CRNs, the channel availability is uncertainty due to the existence of PUs, resulting in intermittent communication. Transmission control protocol (TCP) performance may significantly degrade in such conditions. To address the challenges, some transport protocols have been proposed for reliable transmission in CRNs. In this paper we survey the state-of-the-art transport protocols for CRNs. We firstly highlight the unique aspects of CRNs, and describe the challenges of transport protocols in terms of PU behavior, spectrum sensing, spectrum changing and TCP mechanism itself over CRNs. Then, we provide a summary and comparison of existing transport protocols for CRNs. Finally, we discuss several open issues and research challenges. To the best of our knowledge, our work is the first survey on transport protocols for CRNs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.5
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• pp.1514-1531
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• 2014

Femtocell provides better coverage and higher spectrum efficiency in areas rarely covered by macrocells. However, serious two-tier interference emerging from randomly deploying femtocells may create dead zones where the service is unavailable for macro-users. In this paper, we present adopting cognitive radio spectrum overlay to avoid intra-tier interference and incorporating spectrum underlay and overlay to coordinate cross-tier interference. It is a novel centralized control strategy appropriate for both uplink and downlink transmission. We introduce the application of proper spectrum sharing strategy plus optimal power allocation to address the issue of OFDM-based femtocells interference-limited downlink transmission, along with, a low-complexity suboptimal solution proposed. Simulation results illustrate the proposed optimal scheme achieves the highest transmission rate on successfully avoiding two-tier interference, and outperforms the traditional spectrum underlay or spectrum overlay, via maximizing the opportunity to transmit. Moreover, the strength of our proposed schemes is further demonstrated by comparison with previous classic power allocation methods, in terms of transmission rate, computational complexity and signal peak-to-average power ratio.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.73-76
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• 2015

In this paper, we propose energy harvesting apply to spectrum sensing. In this case, we can be spectrum sensing without consume energy. Algorithms of sensing and harvesting are determine active or idle of primary network, Compares with the threshold energy and the amount of energy that is harvested by energy harvesting scheme. If the secondary network want to send a message while the primary network is active, secondary users will change frequency to use the spectrum. Further, if the secondary network has not message, it will continues harvest energy. Therefore, spectrum sensing applied the energy harvesting method, energy of secondary network is remove waste and charge energy. So, efficiency and utilization of cognitive network can be increase.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.13 no.4
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• pp.315-323
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• 2013

Vessel Traffic Service (VTS) is being used at ports and in coastal areas of the world for preventing accidents and improving efficiency of the vessels at sea on the basis of "IMO RESOLUTION A.857 (20) on Guidelines for Vessel Traffic Services". Currently, VTS plays an important role in the prevention of maritime accidents, as ships are required to participate in the system. Ships are diversified and traffic situations in ports and coastal areas have become more complicated than before. The role of VTS operator (VTSO) has been enlarged because of these reasons, and VTSO is required to be clearly aware of maritime situations and take decisions in emergency situations. In this paper, we propose a prediction table to improve the work of VTSO through the Cognitive Work Analysis (CWA), which analyzes the VTS work very systematically. The required data were collected through interviews and observations of 14 VTSOs. The prediction tool supports decision-making in terms of a proactive measure for the prevention of maritime accidents.

• Journal of the Ergonomics Society of Korea
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• v.32 no.4
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• pp.363-370
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• 2013

Objective: This study investigates the influences of vibrations on hedonic satisfaction based on four kinds of perceptions (perceived ease of use, perceived usefulness, perceived enjoyment, cognitive concentration) when mobile gaming. Background: As mobile gaming is becoming more and more popular for smartphone users, they might want to have more hedonic satisfaction instead of focusing on traditional usability criteria such as efficiency, effectiveness, and satisfaction. Method: We conducted a human-factors experiment with 35 male subjects to evaluate hedonic satisfaction in the mobile game configured by 7 vibration types having different levels of intensity and length. Results: The results revealed that the use of vibration significantly increases the perceived ease of use, perceived usefulness, and cognitive concentration. In addition, the intensity of vibration makes differences of perceived usefulness and cognitive concentration. Conclusion: Vibration can be effectively used to improve hedonic satisfaction of smartphone users in mobile gaming when they are not allowed to turn the sound effects on. Application: This study helps game designers effectively provide vibration feedback of mobile games for smartphone users.

• Journal of Communications and Networks
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• v.18 no.4
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• pp.610-618
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• 2016

A green cognitive radio network (CRN), characterized by base stations (BSs) that conserve energy during sleep periods, is a promising candidate for realizing more efficient spectrum allocation. To improve the spectrum efficiency and achieve greener communication in wireless applications, we consider CRNs with an long term evolution advanced (LTE-A) structure and propose a novel energy-saving strategy. By establishing a type of preemptive priority queueing model with a single vacation, we capture the stochastic behavior of the proposed strategy. Using the method of matrix geometric solutions, we derive the performance measures in terms of the average latency of secondary user (SU) packets and the energy-saving degree of BSs. Furthermore, we provide numerical results to demonstrate the influence of the sleeping parameter on the system performance. Finally, we compare the Nash equilibrium behavior and social optimization behavior of the proposed strategy to present a pricing policy for SU packets.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.3810-3830
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• 2015

In this paper, we investigate the differential game theoretic approach for distributed dynamic cooperative power control in cognitive radio ad hoc networks (CRANETs). First, a payoff function is defined by taking into consideration the tradeoff between the stock of accumulated power interference to the primary networks and the dynamic regulation of the transmit power of secondary users (SUs). Specifically, the payoff function not only reflects the tradeoff between the requirement for quickly finding the stable available spectrum opportunities and the need for better channel conditions, but also reveals the impact of the differentiated types of data traffic on the demand of transmission quality. Then the dynamic power control problem is modeled as a differential game model. Moreover, we convert the differential game model into a dynamic programming problem to obtain a set of optimal strategies of SUs under the condition of the grand coalition. A distributed dynamic cooperative power control algorithm is developed to dynamically adjust the transmit power of SUs under grand coalition. Finally, numerical results are presented to demonstrate the effectiveness of the proposed algorithm for efficient power control in CRANETs.

• Convergence Security Journal
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• v.4 no.3
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• pp.91-99
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• 2004

Nowadays, Providing lunch for schoolchildren was carried out from elementary school to high school in order to plot sound mind and body of students and improve eating habits of people and lighten packing lunch-basket of parents. In this paper, It manage burdensome affairs of user who engaged in work of providing lunch for school children, easily and quickly. Also implement system based on cognitive science through the reuseability, simplicity of use and a design paid attention to efficiency.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1753-1758
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• 2005

Human Adaptive Mechatronics (HAM), which is a system concept to adapt human characteristics, has been proposed. As the HAM application, this paper addresses an information emphasis scheme to alert some hazards which are undetectable by a human operator. The emphasis scheme employs cognitive psychological approach to human discrimination characteristics because excess or deficient emphasis may disturb the operation. One of advantages of teleoperation system is able to include human valuable abilities as global environment recognition, planning, prediction and so on. To implement these abilities to mechanical system is difficult because of not enough intelligence. Proposed teleoperation system is designed to progress the human abilities, and moreover, to not disturb the abilities. In this paper, we consider that the discrimination characteristics depend on window positions on GUI display and operator's individuality. Finally, the efficiency of the alert scheme is verified by some experiments.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.3
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• pp.163-171
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• 2013

Various web browsers offer mouse gesture functions because they are convenient input methods. Mouse gestures enable users to move to the previous page or tab without clicking its relevant icon or menu of the web browser. To maximize the efficiency of mouse gestures, they should be designed to match users' mental models. Mental models of human beings are used to make accurate predictions and reactions when certain information has been recognized by humans. This means providing users with appropriate information about mental models will lead to fast understanding and response. A cognitive response test was performed in order to evaluate whether the mouse gestures easily associate with their respective functional meanings or not. After extracting mouse gestures which needed improvement, those were redesigned to reduce cognitive load via sketch maps. The methods presented in this study will be of help for evaluating and designing mouse gestures.