• Title/Summary/Keyword: Sensing

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Microwave Remote Sensing System Development in MACRES

  • Mahmood, K.A.;Ali, A.;Yusof, S.;Ahmad, Z.;Jamil, H.;Ibrahim, N.;Aziz, H.;Abu Bakar, S.B.
    • Proceedings of the KSRS Conference
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    • 2003.11a
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    • pp.1012-1014
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    • 2003
  • Since it's establishment Malaysian Center for Remote Sensing (MACRES) has focused on the measurements from airborne and space borne remote sensors. In the year 1999 MACRES in collaboration with Multimedia University Malaysia (MMU) began developing it's own remote sensing sensors to meet Malaysian Remote Sensing needs. MACRES adopted a very systematic approached to the development of these microwave sensors. Starting from non-imaging ground base microwave remote sensing sensors MACRES is now well into developing it's first Airborne Synthetic Aperture Radar. With the capability of developing it's own sensors MACRES will profit more on the microwave remote sensing application research. This paper will demonstrate MACRES capability in developing Microwave Remote Sensing Sensors to meet Malaysian remote sensing society needs.

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Complexity based Sensing Strategy for Spectrum Sensing in Cognitive Radio Networks

  • Huang, Kewen;Liu, Yimin;Hong, Yuanquan;Mu, Junsheng
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.9
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    • pp.4372-4389
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    • 2019
  • Spectrum sensing has attracted much attention due to its significant contribution to idle spectrum detection in Cognitive Radio Networks. However, specialized discussion is on complexity-based sensing strategy for spectrum sensing seldom considered. Motivated by this, this paper is devoted to complexity-based sensing strategy for spectrum sensing. Firstly, three efficiency functions are defined to estimate sensing efficiency of a spectrum scheme. Then a novel sensing strategy is proposed given sensing performance and computational complexity. After that, the proposed sensing strategy is extended to energy detector, Cyclostationary feature detector, covariance matrix detector and cooperative spectrum detector. The proposed sensing strategy provides a novel insight into sensing performance estimation for its consideration of both sensing capacity and sensing complexity. Simulations analyze three efficiency functions and optimal sensing strategy of energy detector, Cyclostationary feature detector and covariance matrix detector.

Sensing Period Adaptation using the Cost Function in the Cognitive Radio Networks (인지 무선 네트워크에서 시스템 비용함수를 이용한 적응적 센싱주기)

  • Gao, Xiang;Park, Hyung-Kun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.2
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    • pp.321-323
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    • 2012
  • Cognitive radio has been recently proposed to dynamically access unused-spectrum. Since the spectrum availability for opportunistic access is determined by spectrum sensing, sensing is identified as one of the most crucial issues of cognitive radio networks. The PHY-layer sensing, as a part of spectrum sensing in cognitive radio, concerns the sensing mechanism to determine channel to be sensed and to access. One of the important issues in the PHY-layer sensing control is to find an available sensing period and trade-off between spectrum sensing and data transmission. In this paper, we show the relationship between spectrum sensing and data transmission according to the sensing period. We analyze and propose the new scheme to evaluate optimal sensing period.

REMOTE SENSING OF THE CHINA SEAS AT ORSI/OUC

  • HE, Ming-Xia;Zeng, Kan;Chen, Haihua;Zhang, Tinglu;Hu, Lianbo;Liu, Zhishen;Wu, Songhua;Zhao, Chaofang;Guan, Lei;Hu, Chuanmin
    • Proceedings of the KSRS Conference
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    • v.1
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    • pp.11-14
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    • 2006
  • We present an overview on the observation and research for the China seas using both field experiments and multi-sensor satellite data at ORSI/OUC, covering two topics: (1) Spatial and temporal distribution of internal waves in the China Seas and retrieval of internal wave parameters; (2) Retrieval, validation, and cross-comparison of multi-sensor ocean color data as well as ocean optics in situ experiments in the East China Sea. We also present an incoherent Doppler wind lidar, developed by ORSI, and its observation for marine-atmospheric boundary layer.

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Opportunistic Reporting-based Sensing-Reporting-Throughput Optimization Scheme for Cooperative Cognitive Radio Networks

  • So, Jaewoo
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.3
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    • pp.1319-1335
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    • 2017
  • This paper proposes an opportunistic reporting-based sensing-reporting-throughput optimization scheme that maximizes the spectral efficiency of secondary users (SUs) in cooperative cognitive radio networks with a soft combining rule. The performance of cooperative spectrum sensing depends on the sensing time, the reporting time of transmitting sensing results, and the fusion scheme. While longer sensing time and reporting time improve the sensing performance, this shortens the allowable data transmission time, which in turn degrades the spectral efficiency of SUs. The proposed scheme adopts an opportunistic reporting scheme to restrain the reporting overhead and it jointly controls the sensing-reporting overhead in order to increase the spectral efficiency of SUs. We show that there is a trade-off between the spectral efficiency of SUs and the overheads of cooperative spectrum sensing. The numerical results demonstrate that the proposed scheme significantly outperforms the conventional sensing-throughput optimization schemes when there are many SUs. Moreover, the numerical results show that the sensing-reporting time should be jointly optimized in order to maximize the spectral efficiency of SUs.

Optimal Sensing Time for Maximizing the Throughput of Cognitive Radio Using Superposition Cooperative Spectrum Sensing

  • Vu-Van, Hiep;Koo, Insoo
    • Journal of information and communication convergence engineering
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    • v.13 no.4
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    • pp.221-227
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    • 2015
  • Spectrum sensing plays an essential role in a cognitive radio network, which enables opportunistic access to an underutilized licensed spectrum. In conventional cooperative spectrum sensing (CSS), all cognitive users (CUs) in the network spend the same amount of time on spectrum sensing and waste time in remaining silent when other CUs report their sensing results to the fusion center. This problem is solved by the superposition cooperative spectrum sensing (SPCSS) scheme, where the sensing time of a CU is extended to the reporting time of the other CUs. Subsequently, SPCSS assigns the CUs different sensing times and thus affects both the sensing performance and the throughput of the system. In this paper, we propose an algorithm to determine the optimal sensing time of each CU for SPCSS that maximizes the achieved system throughput. The simulation results prove that the proposed scheme can significantly improve the throughput of the cognitive radio network compared with the conventional CSS.

Design Issues of Spectrum Sensing in Cognitive Radio Networks

  • Kang, Bub-Joo
    • Journal of information and communication convergence engineering
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    • v.9 no.2
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    • pp.166-171
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    • 2011
  • This paper investigates the design issues of spectrum sensing in the cognitive radio (CR) networks of opportunistic unlicensed spectrum access. The cognitive radios can perform a communication using the incumbent user spectrum band without the interference caused by the cognitive radio users. In this case, the cognitive radios must know the real-time radio environments of the incumbent user spectrum band using the spectrum sensing, beacon signal, and geo-location database access. Then in this paper, we are going to provide spectrum sensing issues which include the sensing techniques, the regulatory requirements, the analysis of DTV detection threshold, and main considerations associated with the spectrum sensing design in cognitive radio systems. Also, this paper introduces design trade-offs in order to optimize the sensing parameters such as sensing time and sensing complexity.

A Proactive Dynamic Spectrum Access Method against both Erroneous Spectrum Sensing and Asynchronous Inter-Channel Spectrum Sensing

  • Gu, Junrong;Jang, Sung-Jeen;Kim, Jae-Moung
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.6 no.1
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    • pp.361-378
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    • 2012
  • Most of the current frequency hopping (FH) based dynamic spectrum access (DSA) methods concern a reactive channel access scheme with synchronous inter-channel spectrum sensing, i.e., FH is reactively triggered by the primary user (PU)'s return reported by spectrum sensing, and the PU channel to be switched to is assumed precisely just sensed or ready to be sensed, as if the inter-channel spectrum sensing moments are synchronous. However, the inter-channel spectrum sensing moments are more likely to be asynchronous, which risks PU suffering more interference. Moreover, the spectrum sensing is usually erroneous, which renders the problem more complex. To address this problem, we propose a proactive FH based DSA method against both erroneous spectrum sensing and asynchronous inter-channel spectrum sensing (moments). We term it as proactive DSA. The optimal FH sequence is obtained by dynamic programming. The complexity is also analyzed. Finally, the simulation results confirm the effectiveness of the proposed method.

A Study on Performance Evaluation of Energy-Constrained Open-Loop Cooperative Sensing in Cognitive Radios (인지 무선 통신 시스템에서 에너지 제한적 개방 루프 협력 센싱 기법에 대한 연구)

  • Noh, Gosan;Lim, Sungmook;Wang, Hanho
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.63 no.1
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    • pp.34-39
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    • 2014
  • In cognitive radios, secondary users can use the spectrum exclusively allocated to a primary wireless system if the secondary users detect the spectrum in idle states. Because the secondary users can utilize the idle state of the spectrum, the utilization rate of the spectrum can be improved. The idle states can be detected by using secondary users' sensing schemes. However, the wireless channel environment where secondary users perform the spectrum sensing is not very friendly to secondary users because the signal-to-noise ratio of the received primary signal is very low. Hence, cooperative sensing scheme where more than one secondary user take part in the spectrum sensing is generally used in cognitive radios. In this paper, we investigate the cooperative sensing performance for machine-to-machine communication devices operated by batteries with limited energy. In general, the energy consumed for the spectrum sensing increases as the length of the sensing period and the number of cooperative sensing nodes. Accordingly, even though the total amount of the consumed energy is the same, an energy allocation methodology how to distribute the energy to the sensing period and sensing nodes can achieve the optimum sensing performance, which is numerically analyzed.