• Title/Summary/Keyword: Pilot Sensing

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Interference Avoidance through Pilot-Based Spectrum Sensing Algorithm in Overlaid Femtocell Networks

  • Sambanthan, Padmapriya;Muthu, Tamilarasi
    • ETRI Journal
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    • v.38 no.1
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    • pp.30-40
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    • 2016
  • Co-channel interference between macro-femtocell networks is an unresolved problem, due to the frequency reuse phenomenon. To mitigate such interference, a secondary femtocell must acquire channel-state knowledge about a co-channel macrocell user and accordingly condition the maximum transmit power of femtocell user. This paper proposes a pilot-based spectrum sensing (PSS) algorithm for overlaid femtocell networks to sense the presence of a macrocell user over a channel of interest. The PSS algorithm senses the pilot tones in the received signal through the power level and the correlation metric comparisons between the received signal and the local reference pilots. On ensuring the existence of a co-channel macrocell user, the maximum transmit power of the corresponding femtocell user is optimized so as to avoid interference. Time and frequency offsets are carefully handled in our proposal. Simulation results show that the PSS algorithm outperforms existing sensing techniques, even at poor received signal quality. It requires less sensing time and provides better detection probability over existing techniques.

Pilot Tone Design for PAPR Reduction in OFDM Systems Based on Compressed Channel Sensing (압축 채널 센싱 기반 OFDM 시스템에서 PAPR 감소를 위한 파일럿 톤 설계 방법)

  • Jang, Min-Ho;Kim, Kee-Hoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.5
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    • pp.806-808
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    • 2015
  • In this paper, we suggest the method of pilot tone design for a compressed channel sensing in order to decrease the peak to average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems.

Effective Cooperative FFT based pilot Sensing Scheme for Detecting DTV Signals in Cognitive Radio (인지무선 시스템에서 DTV 신호 검출을 위한 FFT 기반의 협력 파일럿 센싱)

  • Lee, So-Young;Kim, Eun-Cheol;Kim, Jin-Young
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.9 no.1
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    • pp.27-33
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    • 2010
  • Cognitive radio (CR), which is proposed as a technology that utilizes the frequency resources effectively, has been studied to relive scarcity of the frequency resources. Also, FCC revises the regulation to reuse the TV white spaces for applying CR system and allows to use the TV white spaces by CR devices and use of CR device may be regularized after conversion by DTV in 2009. In order to reuse the TV bands without harmful interference to primary user, correct spectrum sensing should be needed to detect DTV signals that is the primary user in TV bands. In this paper, we detect the DTV signal using FFT-based pilot sensing and cooperative sensing scheme is applied for the reliability of the sensing performance and the accuracy of the detection probability. Also, in order to make the reliable decision, the majority rule is proposed.

Threshold Determination Methods for Cognitive Radio in Real DTV Bandwidth (실제 DTV 대역에서 인지 무선 시스템 적용을 위한 임계값 결정 방법)

  • Kim, Seung Jong;Lee, Sun Yui;Kim, Jin Young
    • Journal of Satellite, Information and Communications
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    • v.9 no.1
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    • pp.22-27
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    • 2014
  • In this paper, we analyzed performance of FFT based on pilot sensing scheme for DTV signal in fading environments. In order to detect the present and absent for advanced television system committee digital television (ATSC DTV), a pilot detection scheme based on FFT is employed. Also, these signals are applied to each fading environment. For evaluating the spectrum sensing performance, detection probability is derived. When threshold is decided, we refer to constant false alarm rate (CFAR) scheme. From simulation results, it is confirmed that the spectrum sensing performance is improved as increase of the false alarm rate. The result of this paper can be applied to implement the spectrum sensing part of cognitive radio (CR) systems.

Location of pressure sensing holes in MPA flowmeter and discharge coefficients (MPA 유량계 압력감지공의 위치와 유출계수)

  • Kim, Raymond K.;Choi, Sung Kil
    • 유체기계공업학회:학술대회논문집
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    • 2004.12a
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    • pp.160-165
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    • 2004
  • MPA (Multi-Point Averaging) flow element is a new type of differential pressure (DP) flow-sensing device that was developed by Seojin Instech to improve the operating characteristics of the conventional Averaging Pilot Tube (APT) flow elements. Operating characteristics of a flowmeter in general can be defined in terms of measurement accuracy and range. Improvement of accuracy and expanding the range of flow measurement were the two main objectives of the development. To achieve these dual objectives several upstream and downstream pressure-sensing holes were placed in MPA flow element. During the course of the development it was found that certain arrangements of the pressure-sensing holes improved measurement accuracy but did not expand operating flow range of Averaging Pilot Tubes. Development tests were performed with water between Reynolds number of 50,000 and 1,000,000 in the four-inch test line at the Alden Research Laboratory, U.S.A. Purpose of this paper is to present the relationship between the various locations of the pressure-sensing holes and the performance characteristics of MPA flow element. Furthermore, the operating characteristics of the best performing MPA are compared with those of typical orifice and APT.

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Performance of Spectrum Sensing for ATSC DTV Signals (ATSC DTV 신호 검출 성능)

  • Lee, So-Young;Kim, Eun-Cheol;Kim, Jin-Young
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.10 no.3
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    • pp.167-172
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    • 2010
  • In this paper, we analyze and simulate the performance of a pilot signal detection algorithm based on fast Fourier transform (FFT) for several system parameters in order to detect advanced television system committee digital television (ATSC DTV) signals. Requirements for detecting DTV signals are analyzed. And the detection performance is compared according to sensing frequency and time. Form the simulation results, it is confirmed that the signal detection performance increases as the sensing frequency rises. The results of this paper can be applied for implementing cognitive radio (CR) systems in the frequency band of DTV signals.

Massive MIMO Channel Estimation Algorithm Based on Weighted Compressed Sensing

  • Lv, Zhiguo;Wang, Weijing
    • Journal of Information Processing Systems
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    • v.17 no.6
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    • pp.1083-1096
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    • 2021
  • Compressed sensing-based matching pursuit algorithms can estimate the sparse channel of massive multiple input multiple-output systems with short pilot sequences. Although they have the advantages of low computational complexity and low pilot overhead, their accuracy remains insufficient. Simply multiplying the weight value and the estimated channel obtained in different iterations can only improve the accuracy of channel estimation under conditions of low signal-to-noise ratio (SNR), whereas it degrades accuracy under conditions of high SNR. To address this issue, an improved weighted matching pursuit algorithm is proposed, which obtains a suitable weight value uop by training the channel data. The step of the weight value increasing with successive iterations is calculated according to the sparsity of the channel and uop. Adjusting the weight value adaptively over the iterations can further improve the accuracy of estimation. The results of simulations conducted to evaluate the proposed algorithm show that it exhibits improved performance in terms of accuracy compared to previous methods under conditions of both high and low SNR.

ONE BIG STEP FORWARD IN THE TELEMATICS REVOLUTION : JEJU TELEMATICS PILOT PROJECT

  • Jang In-Sung;Ryu Jae-Jun;Choi Wan-Sik;Park Jong-Hyn
    • Proceedings of the KSRS Conference
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    • 2005.10a
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    • pp.579-581
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    • 2005
  • One of the latest wonders brought to us by ICT(Information and Communication Technology) is telematics turning automobiles, not long ago a mere means of transportation, into a whole-new digital living space. Telematics is indeed fast becoming a household word, and countries around the globe are giving spur to research and development of core technologies to acquire competitiveness in related IT sectors. This paper discusses the telematics pilot project launched in Jeju to promote the development of telematics technology and stimulate related industries. The objective of the pilot project is to give impetus to research in related technologies and a head-start to Korea in the global race in this technology field. The pilot deployment, covering 6 services, promising to be most demanded in Korea's telematics environment, is sure to make a sizeable contribution toward familiarizing the public with the new technology.

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ATSC Digital Television Signal Detection with Spectral Correlation Density

  • Yoo, Do-Sik;Lim, Jongtae;Kang, Min-Hong
    • Journal of Communications and Networks
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    • v.16 no.6
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    • pp.600-612
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    • 2014
  • In this paper, we consider the problem of spectrum sensing for advanced television systems committee (ATSC) digital television (DTV) signal detection. To exploit the cyclostationarity of the ATSC DTV signals, we employ spectral correlation density (SCD) as the decision statistic and propose an optimal detection algorithm. The major difficulty is in obtaining the probability distribution functions of the SCD. To overcome the difficulty, we probabilistically model the pilot frequency location and employ Gaussian approximation for the SCD distribution. Then, we obtain a practically implementable detection algorithm that outperforms the industry leading systems by 2-3 dB. We also propose various techniques that greatly reduce the system complexity with performance degradation by only a few tenths of decibels. Finally, we show how robust the system is to the estimation errors of the noise power spectral density level and the probability distribution of the pilot frequency location.