An Approach of Selection Method In Spectrum Sensing Under Rayleigh Fading

Truc Tran Thanh,Jeong-Beom Ha,Cha-Yeon Won,Hyung-Yun Kong 한국통신학회 2012 한국통신학회 학술대회논문집 Vol.2012 No.2

A Method to Avoid Mutual Interference in a Cooperative Spectrum Sharing System

Tran, Truc Thanh,Kong, Hyung Yun The Korea Institute of Information and Commucation 2014 Journal of communications and networks Vol.16 No.2

This article proposes a spectrum sharing method which can avoid the mutual interference in both primary and secondary systems. The two systems make them a priority to use two single-dimension orthogonal signals, the real and imaginary pulse amplitude modulation signals, if the primary system is not in outage with this use. A secondary transmitter is selected to be the primary relay and the active secondary source to perform this. This allows a simultaneous spectrum access without any mutual interference. Otherwise, the primary system attempts to use a full two-dimensional signal, the quadrature amplitude modulation signal. If there is no outage with respect to this use, the secondary spectrum access is not allowed. When both of the previous attempts fail, the secondary system is allowed to freely use the spectrum two whole time slots. The analysis and simulation are provided to analyze the outage performance and they validate the considerable improvement of the proposed method as compared to the conventional one.

A Method to Avoid Mutual Interference in a Cooperative Spectrum Sharing System

Truc Thanh Tran,공형윤 한국통신학회 2014 Journal of communications and networks Vol.16 No.2

This article proposes a spectrum sharing method whichcan avoid the mutual interference in both primary and secondarysystems. The two systems make them a priority to use two singledimensionorthogonal signals, the real and imaginary pulse amplitudemodulationsignals, if the primary system is not in outage withthis use. A secondary transmitter is selected to be the primary relayand the active secondary source to perform this. This allows a simultaneousspectrumaccess without anymutual interference. Otherwise,the primary system attempts to use a full two-dimensionalsignal, the quadrature amplitude modulation signal. If there is nooutage with respect to this use, the secondary spectrumaccess is notallowed. When both of the previous attempts fail, the secondarysystem is allowed to freely use the spectrum two whole time slots. The analysis and simulation are provided to analyze the outage performanceand they validate the considerable improvement of theproposed method as compared to the conventional one.

Exploitation of Spatial Diversity in a Novel Cooperative Spectrum Sharing Method based on PAM and Modified PAM Modulation

Truc Thanh Tran,공형윤 한국통신학회 2014 Journal of communications and networks Vol.16 No.3

This article presents a novel cooperative spectrum sharing(CSS) scheme. The primary transmitter transmits a complexQuadrature amplitude modulation (QAM) signal in the first phase,and CSS occurs in the second phase. The secondary transmitterwith the largest forwarding channel gain among the nodes that successfullydecode the primary signal in the first phase is selectedfor CSS. This selected node employs a pulse-amplitude modulation(PAM) signal for primary information message (IM) insteadof the QAM signal, and it employs a modified PAM signal for thesecondary IM. The proposed modified PAM signal depends on theamplitude of the primary PAM signal. This method results in nomutual interference and negligible primary interference constraintand allows a higher degree of exploitation of spatial diversity, thusenabling increase in secondary power to improve primary transmission. The outage performance is enhanced in both the primaryand secondary systems. The critical region, in which the primaryoutage performance is enhanced with the proposed CSS scheme,can be adjusted and widened by varying either the modulation cooperationsharing factor or the number of secondary transmitters.

An Algorithm to Reduce the Number of Nodes in Active Spectrum Sensing Via Cooperative Sequential Detection

Tran Thanh Truc,Hyung Yun Kong 한국전자파학회JEES 2012 Journal of Electromagnetic Engineering and Science Vol.12 No.2

In this paper, we propose an algorithm to conserve resources of the common control channel in a cognitive radio network by rejecting the redundant users using cooperative spectrum sensing. The proposed scheme is investigated under the paradigm of active spectrum sensing and a sequential detection technique. The algorithm is based on the J-divergence between the hypotheses of non primary user operation and the otherwise case. We select the most significant eigenvalues, which primarily affect the global statistical test. For the case where interference is from a secondary system transmission, a match filter is first employed to remove the degradation, and then the proposed algorithm is employed to remove the cooperative sensing nodes. Numerical results are provided and compared with conventional cases in order to validate the performance of the proposed algorithm.

Cooperative Spectrum Sensing Via Sequential Detection

Truc Tran Thanh,Hyung Yun Kong 한국전자파학회JEES 2012 Journal of Electromagnetic Engineering and Science Vol.12 No.3

Spectrum sensing is one of the most important functions in cognitive radio systems. In this paper, we focus on reducing the sensing time in a cooperative spectrum sensing paradigm. In the proposed scheme, a sequential detection technique is employed to provide a robust and quick detection system. Each of the secondary users measures the log-likelihood probability of the received signals and then sequentially reports to the base station. Here, the maximum ratio combining (MRC) technique is employed to reduce the average sample number (ASN) in order to reduce the sensing time. This proposed scheme is analyzed and simulated to illustrate the performance in comparison with the other given methods. Analysis and simulation are provided to validate the proposed method.

Block-Time of Arrival/Leaving Estimation to Enhance Local Spectrum Sensing under the Practical Traffic of Primary User

Truc Thanh Tran,공형윤 한국통신학회 2013 Journal of communications and networks Vol.15 No.5

With a long sensing period, the inter-frame spectrumsensing in IEEE 802.22 standard is vulnerable to the effect of thetraffic of the primary user (PU). In this article, we address the twodegrading factors that affect the inter-frame sensing performancewith respect to the random arrival/leaving of the PU traffic. Theyare the noise-only samples under the random arrival traffic, andthe PU-signal-contained samples under the random leaving traffic. We propose the model in which the intra-frame sensing cooperateswith the inter-frame one, and the inter-frame sensing uses the timeof-arrival (ToA), and time-of-leave (ToL) detectors to reduce thetwo degrading factors in the inter-frame sensing time. These ToAand ToL detectors are used to search for the sample which containseither the ToA or ToL of the PU traffic, respectively, whichallows the partial cancelation of the unnecessary samples. At thefinal stage, the remaining samples are input into a primary userdetector, which is based on the energy detection scheme, to determinethe status of PU traffic in the inter-frame sensing time. Theanalysis and the simulation results show that the proposed schemeenhances the spectrum-sensing performance compared to the conventionalcounter-part.

A Method Enabling Exploitation of Spatial Diversity and Physical Layer Security in an Extreme Case of Source-Wiretapping without a Jamming Beamformer

Truc Thanh Tran,공형윤 한국통신학회 2015 Journal of communications and networks Vol.17 No.5

This article exploits spatial diversity for jamming to prevent wiretapping in the extreme case in which an eavesdropper is located near the source and a common jamming signal is unavailable. To address this challenge, the jamming signal is allowed to carry a random binary message. Then, it is proposed that the active intermediate node transmits this jamming signal and the decoding of this signal at both source and destination is physically secured as result of using the physical-layer security method. If the source and the destination securely and correctly decode this jamming message, the source transmits another message which is created from combining its information message and the decoded message using the network-coding method. Therefore, this method prevents the transmissions from being eavesdropped upon by the source-wiretapping.

An Analysis of Combining Methods in Cooperative Spectrum Sensing over Rayleigh Fading Channel

Tran Thanh Truc,Hyung-Yun Kong 한국전자파학회JEES 2010 Journal of Electromagnetic Engineering and Science Vol.10 No.3

This paper evaluates the performance of two methods of spectrum sensing: the linear combining method and the selection combining method which is based on maximum SNR of sensing channel. We proposed a rule for global detection for the purpose of combating hidden terminal problems in spectrum sensing. Our analysis considers a situation when sensing channels experience the non-identically, independently distributed(n.i.d) Rayleigh fading. The average probabilities of global detection in these methods are derived and compared. In the scope of this paper, the reporting channels are assumed to be the AWGN channel with invariant and identical gain during the system’s operation.

Block-Time of Arrival/Leaving Estimation to Enhance Local Spectrum Sensing under the Practical Traffic of Primary User

Tran, Truc Thanh,Kong, Hyung Yun The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.5

With a long sensing period, the inter-frame spectrum sensing in IEEE 802.22 standard is vulnerable to the effect of the traffic of the primary user (PU). In this article, we address the two degrading factors that affect the inter-frame sensing performance with respect to the random arrival/leaving of the PU traffic. They are the noise-only samples under the random arrival traffic, and the PU-signal-contained samples under the random leaving traffic. We propose the model in which the intra-frame sensing cooperates with the inter-frame one, and the inter-frame sensing uses the time-of-arrival (ToA), and time-of-leave (ToL) detectors to reduce the two degrading factors in the inter-frame sensing time. These ToA and ToL detectors are used to search for the sample which contains either the ToA or ToL of the PU traffic, respectively, which allows the partial cancelation of the unnecessary samples. At the final stage, the remaining samples are input into a primary user detector, which is based on the energy detection scheme, to determine the status of PU traffic in the inter-frame sensing time. The analysis and the simulation results show that the proposed scheme enhances the spectrum-sensing performance compared to the conventional counter-part.