• Title, Summary, Keyword: mobility spectrum

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Mobility-Spectrum Analysis of an Anisotropic Material System with a Single-Valley Indirect-Band-Gap Semiconductor Quantum-Well

  • Joung, Hodoug;Ahn, Il-Ho;Yang, Woochul;Kim, Deuk Young
    • Electronic Materials Letters
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    • v.14 no.6
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    • pp.774-783
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    • 2018
  • Full maximum-entropy mobility-spectrum analysis (FMEMSA) is the best algorithm among mobility spectrum analyses by which we can obtain a set of partial-conductivities associated with mobility values (mobility spectrum) by analyzing magnetic-field-dependent conductivity-tensors. However, it is restricted to a direct band-gap semiconductor and should be modified for materials with other band structures. We developed the modified version of FMEMSA which is appropriate for a material with a single anisotropic valley, or an indirect-band-gap semiconductor quantum-well with a single non-degenerate conduction-band valley e.g., (110)-oriented AlAs quantum wells with a single anisotropic valley. To demonstrate the reliability of the modified version, we applied it to several sets of synthetic measurement datasets. The results demonstrated that, unlike existing FMEMSA, the modified version could produce accurate mobility spectra of materials with a single anisotropic valley.

Efficient Spectrum Allocation Method for Cognitive Radio in IEEE 802.22 WRAN (IEEE 802.22 WRAN에서 Cognitive Radio를 위한 효율적인 Spectrum 할당 기법)

  • Kim, Joo-Seok;Kim, Kyung-Seok;Park, Woo-Goo;Kim, Jin-Up
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.12B
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    • pp.1068-1075
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    • 2006
  • Frequency resource value is growing bigger more with the development of the wireless communication. But Frequency shortage phenomenon is risen seriously because the need of Frequency resource is very many compared with the supply in an information society of the future. So we need Cognitive technique Radio which is taking the attention recently to use Frequency resource not to be not using efficiently. We propose efficient Dynamic Spectrum Allocation method in IEEE a 802.22 WRAN environment of CR foundation in this paper. To share spectrum more efficiently, we presented some Dynamic Spectrum Allocation technique to apply the Variable bandwidth, Mobility and verified this through the result of the simulations.

A Novel Prediction-based Spectrum Allocation Mechanism for Mobile Cognitive Radio Networks

  • Wang, Yao;Zhang, Zhongzhao;Yu, Qiyue;Chen, Jiamei
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.7 no.9
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    • pp.2101-2119
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    • 2013
  • The spectrum allocation is an attractive issue for mobile cognitive radio (CR) network. However, the time-varying characteristic of the spectrum allocation is not fully investigated. Thus, this paper originally deduces the probabilities of spectrum availability and interference constrain in theory under the mobile environment. Then, we propose a prediction mechanism of the time-varying available spectrum lists and the dynamic interference topologies. By considering the node mobility and primary users' (PUs') activity, the mechanism is capable of overcoming the static shortcomings of traditional model. Based on the mechanism, two prediction-based spectrum allocation algorithms, prediction greedy algorithm (PGA) and prediction fairness algorithm (PFA), are presented to enhance the spectrum utilization and improve the fairness. Moreover, new utility functions are redefined to measure the effectiveness of different schemes in the mobile CR network. Simulation results show that PGA gets more average effective spectrums than the traditional schemes, when the mean idle time of PUs is high. And PFA could achieve good system fairness performance, especially when the speeds of cognitive nodes are high.

Channel Allocation Using Mobile Mobility and Neural Net Spectrum Hole Prediction in Cellular-Based Wireless Cognitive Radio Networks (셀룰러 기반 무선 인지망에서 모바일 이동성과 신경망 스펙트럼 홀 예측에 의한 채널할당)

  • Lee, Jin-yi
    • The Journal of Advanced Navigation Technology
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    • v.21 no.4
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    • pp.347-352
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    • 2017
  • In this paper, we propose a method that reduces mobile user's handover call dropping probability by using cognitive radio technology(CR) in cellular - based wireless cognitive radio networks. The proposed method predicts a cell to visit by Ziv-Lempel algorithm, and then supports mobile user with prediction of spectrum holes based on CR technology when allocated channels are short in the cell. We make neural network predict spectrum hole resources, and make handover calls use the resources before initial calls. Simulation results show CR technology has the capability to reduce mobile user handover call dropping probability in cellular mobile communication networks.

Priority-based Differentiated Service in Spectrum Mobility Game

  • Lu, Bingxian;Qin, Zhenquan;Wang, Lei;Sun, Liang;Zhu, Ming;Shu, Lei
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.4
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    • pp.1324-1343
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    • 2014
  • In recent years, the problem of spectrum mobility in Cognitive Radio (CR) Networks has been widely investigated. In order to utilize spectrum resources completely, many spectrum handoff techniques based on game theory have been proposed, but most studies only concern that users how to achieve better payoffs, without much attention to the diverse needs of users. In this paper, we propose a new channel-switching model based on game theory, using a prioritized approach to meet the diverse needs of users in two different modes (CQ and PS). At the same time, this paper proposes some acceleration techniques to reach the Nash equilibrium more efficiently. We evaluate the performance of the proposed schemes depending on priority using real channel availability measurements, and conclude that the channel quality function (CQ) mode provide better service for priority user but the plan-sorting (PS) mode can be more suitable in multiple priority users exist scene.

Spectrum Management Models for Cognitive Radios

  • Kaur, Prabhjot;Khosla, Arun;Uddin, Moin
    • Journal of Communications and Networks
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    • v.15 no.2
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    • pp.222-227
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    • 2013
  • This paper presents an analytical framework for dynamic spectrum allocation in cognitive radio networks. We propose a distributed queuing based Markovian model each for single channel and multiple channels access for a contending user. Knowledge about spectrum mobility is one of the most challenging problems in both these setups. To solve this, we consider probabilistic channel availability in case of licensed channel detection for single channel allocation, while variable data rates are considered using channel aggregation technique in the multiple channel access model. These models are designed for a centralized architecture to enable dynamic spectrum allocation and are compared on the basis of access latency and service duration.

Mobile IP User Mobility Model for Effective Mobility Management Accommodating Heterogeneous Networks under Cognitive Networking Environments (이종 네트워크간의 효과적 이동성 수용을 위한 이동 IP 네트워크 사용자 이동성 모델)

  • Cheon, Eun-Ji;Kim, Jeong-Ho
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.49 no.6
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    • pp.90-97
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    • 2012
  • In this paper, the new user mobility model which can be utilized to register user's location for interworking with heterogeneous overlay convergent networks under the time-varying radio propagation environment has been proposed. Thus the user mobility model is considered in order to evaluate the behaviors of users in the overlay convergent networks. This Mobile IP user mobility model will be very useful to model the user mobility behaviors and can be used to estimate the signaling traffic and frequency spectrum demands for massive data transfer for the heterogeneous overlay convergent networks.

Theoretical Calculation on Alpha Track Density by Using an Electrostatic Ion Spectrometer (정전기분광분석방법에 의한 알파입자비적밀도의 이론적 계산연구)

  • Yoon, Suk-Chul;Ha, Chung-Woo
    • Journal of Radiation Protection and Research
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    • v.18 no.1
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    • pp.25-35
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    • 1993
  • To develop a technique of theoretical alpha track density calculation for comparison with measured track density, an electrostatic ion spectrometer was specially designed and fabricated. The mobility spectrum of first radon daughter(Po-218) in the range of $0.07{\sim}5.0cm^2/V\;s$ from the radon chamber was measured using-the electrostatic ion spectrometer. Measurement was taken in a radon chamber operated using dry particle free air passed through silica gel, activated charcoal and molecular sieve filters. The mobility of a new-born Po-218 ion measured by the electrostatic ion spectrometer was determined to be $1.92cm^2/V\;s$. A comparison of the theoretical and measured alpha track densities was completed and uncertainties concerning the shape of the spectrum were analyzed. It was found that the discrepancies in track densities are primarily Que to the neglect of wall loss of ions in the theoretical track density calculation.

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User Mobility Management Scheme for Effective Inter-working with Overlay Convergent Networks (중첩 융합 네트워크에서 효과적 연동을 위한 위치정보 관리방법)

  • Choi, Yu-Mi;Kim, Jeong-Ho
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.49 no.6
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    • pp.83-89
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    • 2012
  • In this paper, the new user mobility management scheme which can be utilized to register user's location for interworking with heterogeneous overlay convergent networks under the time-varying radio propagation environment has been proposed. Thus the user mobility management can be considered in order to model and to evaluate the behaviors of users in the overlay convergent networks. This mobility management scheme will be very useful in characterizing the user mobility behaviors and can be used to estimate the signaling traffic and frequency spectrum demands for massive data transfer for the heterogeneous overlay convergent networks.

Survey of Artificial Intelligence Approaches in Cognitive Radio Networks

  • Morabit, Yasmina EL;Mrabti, Fatiha;Abarkan, El Houssein
    • Journal of information and communication convergence engineering
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    • v.17 no.1
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    • pp.21-40
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    • 2019
  • This paper presents a comprehensive survey of various artificial intelligence (AI) techniques implemented in cognitive radio engine to improve cognition capability in cognitive radio networks (CRNs). AI enables systems to solve problems by emulating human biological processes such as learning, reasoning, decision making, self-adaptation, self-organization, and self-stability. The use of AI techniques is studied in applications related to the major tasks of cognitive radio including spectrum sensing, spectrum sharing, spectrum mobility, and decision making regarding dynamic spectrum access, resource allocation, parameter adaptation, and optimization problem. The aim is to provide a single source as a survey paper to help researchers better understand the various implementations of AI approaches to different cognitive radio designs, as well as to refer interested readers to the recent AI research works done in CRNs.