Pub Date : 2006-07-02DOI: 10.1109/SPAWC.2006.346363
Roberto López-Valcarce, C. Masquera
In certain digital communication systems, such as those using Tomlinson-Harashima precoding and signal shaping, the received symbols are not equiprobable; rather, symbols with more energy are less likely. It is shown that in such scenarios the performance of standard carrier phase estimators is severely degraded. Using a discrete Gaussian model for the symbol probability distribution, we present the likelihood function for phase estimation, as well as an approximate maximum likelihood blind phase estimator. Simulation results show that the proposed estimate is much more robust to non-equiprobable symbol distributions than standard ones
{"title":"Blind Carrier Phase Estimation for Non-Equiprobable Constellations","authors":"Roberto López-Valcarce, C. Masquera","doi":"10.1109/SPAWC.2006.346363","DOIUrl":"https://doi.org/10.1109/SPAWC.2006.346363","url":null,"abstract":"In certain digital communication systems, such as those using Tomlinson-Harashima precoding and signal shaping, the received symbols are not equiprobable; rather, symbols with more energy are less likely. It is shown that in such scenarios the performance of standard carrier phase estimators is severely degraded. Using a discrete Gaussian model for the symbol probability distribution, we present the likelihood function for phase estimation, as well as an approximate maximum likelihood blind phase estimator. Simulation results show that the proposed estimate is much more robust to non-equiprobable symbol distributions than standard ones","PeriodicalId":414942,"journal":{"name":"2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129149826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-02DOI: 10.1109/SPAWC.2006.346398
D. Ampeliotis, K. Berberidis
Soft-input soft-output (SISO) equalizers based on linear filters have proven to be good, low complexity, alternatives to trellis-based SISO equalizers. In particular, the soft interference canceller (SIC) has recently received great interest, especially for receivers performing turbo equalization. In this paper, we modify the way in which the SIC incorporates soft information. In existing literature the input to the cancellation filter is the expectation of the symbols based solely on the a-priori probabilities coming from the decoder, whereas here we propose to use the conditional expectation of those symbols, given both the a-priori probabilities and the received sequence. This modification results in performance gains at the expense of increased computational complexity. However, by introducing an approximation to the aforementioned algorithm a linear complexity SISO equalizer can be derived. Simulation results for an 8-PSK constellation and hostile radio channels have shown the effectiveness of the proposed algorithms in mitigating the inter-symbol interference (ISI)
{"title":"A Linear Complexity Turbo Equalizer Based on a Modified Soft Interference Canceller","authors":"D. Ampeliotis, K. Berberidis","doi":"10.1109/SPAWC.2006.346398","DOIUrl":"https://doi.org/10.1109/SPAWC.2006.346398","url":null,"abstract":"Soft-input soft-output (SISO) equalizers based on linear filters have proven to be good, low complexity, alternatives to trellis-based SISO equalizers. In particular, the soft interference canceller (SIC) has recently received great interest, especially for receivers performing turbo equalization. In this paper, we modify the way in which the SIC incorporates soft information. In existing literature the input to the cancellation filter is the expectation of the symbols based solely on the a-priori probabilities coming from the decoder, whereas here we propose to use the conditional expectation of those symbols, given both the a-priori probabilities and the received sequence. This modification results in performance gains at the expense of increased computational complexity. However, by introducing an approximation to the aforementioned algorithm a linear complexity SISO equalizer can be derived. Simulation results for an 8-PSK constellation and hostile radio channels have shown the effectiveness of the proposed algorithms in mitigating the inter-symbol interference (ISI)","PeriodicalId":414942,"journal":{"name":"2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121500395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-02DOI: 10.1109/SPAWC.2006.346466
M. Muck, S. Rouquette-Léveil, M. de Courville
This contribution derives an algorithm for optimizing the mapping of irregular and systematic low density parity check (LDPC) code word bits onto orthogonal frequency division multiplexing (OFDM) carriers in the context of a frequency selective fading channel in both, a single-transmit single-receive (SISO channel) and multiple-transmit multiple-receive (MIMO channel) antennas scenario. The absolute values of the frequency domain channel coefficients are assumed to be known and the LDPC code to be given (contrary to existing proposals where the LDPC code is optimized with respect to a given propagation channel). The proposed solution can alternatively be interpreted as an adaptive interleaver (which is inherently available in software defined radio type of system implementations) optimized for a given channel impulse response. In a typical WLAN (IEEE802.11n) scenario, the proposed mapping technique improves the system performance by up to approx. 0.7 dB compared to a linear (direct) mapping
{"title":"Reconfigurable Low Density Parity Check (LDPC) Code Interleaving for SIO and MIMO OFDM Systems","authors":"M. Muck, S. Rouquette-Léveil, M. de Courville","doi":"10.1109/SPAWC.2006.346466","DOIUrl":"https://doi.org/10.1109/SPAWC.2006.346466","url":null,"abstract":"This contribution derives an algorithm for optimizing the mapping of irregular and systematic low density parity check (LDPC) code word bits onto orthogonal frequency division multiplexing (OFDM) carriers in the context of a frequency selective fading channel in both, a single-transmit single-receive (SISO channel) and multiple-transmit multiple-receive (MIMO channel) antennas scenario. The absolute values of the frequency domain channel coefficients are assumed to be known and the LDPC code to be given (contrary to existing proposals where the LDPC code is optimized with respect to a given propagation channel). The proposed solution can alternatively be interpreted as an adaptive interleaver (which is inherently available in software defined radio type of system implementations) optimized for a given channel impulse response. In a typical WLAN (IEEE802.11n) scenario, the proposed mapping technique improves the system performance by up to approx. 0.7 dB compared to a linear (direct) mapping","PeriodicalId":414942,"journal":{"name":"2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127704094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-02DOI: 10.1109/SPAWC.2006.346355
R. Gaudel, F. Bonnet, J.B. Domelevo-Entfellner, A. Roumy
In the context of synchronous random DS-CDMA (direct sequence code division multiple access) communications over a mobile network, the receiver that minimizes the per-user bit error rate (BER) is the symbol maximum a posteriori (MAP) detector. This receiver is derived under the hypothesis of perfect channel state information at the receiver. In this paper we consider the case where the channel noise variance is estimated and analyze the effect of this mismatch. We show that the bit error rate (BER) is piecewise monotonic wrt. the estimated noise variance, reaching its minimum for the true channel variance. We also provide an upper bound of the individually optimum receiver performance under noise variance mismatch. Thus we give a theoretical justification for the usual bias towards noise variance underestimation adopted by the community
{"title":"Noise Variance Estimation in DS-CDMA and its Effects on the Individually Optimum Receiver","authors":"R. Gaudel, F. Bonnet, J.B. Domelevo-Entfellner, A. Roumy","doi":"10.1109/SPAWC.2006.346355","DOIUrl":"https://doi.org/10.1109/SPAWC.2006.346355","url":null,"abstract":"In the context of synchronous random DS-CDMA (direct sequence code division multiple access) communications over a mobile network, the receiver that minimizes the per-user bit error rate (BER) is the symbol maximum a posteriori (MAP) detector. This receiver is derived under the hypothesis of perfect channel state information at the receiver. In this paper we consider the case where the channel noise variance is estimated and analyze the effect of this mismatch. We show that the bit error rate (BER) is piecewise monotonic wrt. the estimated noise variance, reaching its minimum for the true channel variance. We also provide an upper bound of the individually optimum receiver performance under noise variance mismatch. Thus we give a theoretical justification for the usual bias towards noise variance underestimation adopted by the community","PeriodicalId":414942,"journal":{"name":"2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications","volume":"325 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132419776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-02DOI: 10.1109/SPAWC.2006.346361
N. Jam, S. Khorsandi, M. Dehghan
The uncertainty principle says that when elementary quantum systems like photons are used for information transmission, it is impossible in principle to eavesdrop on this media without a high probability of disturbing the transmission in such a way as to be detected. By this way we can make an absolutely secure communication link which can not be threaten by any kind of cheating by an opponent with unlimited computing power. Until now quantum transmission of digital information has been implemented using polarized photon transmission over dark fibers or optical wireless links mainly for random key distribution. In this paper we will use the same idea of uncertainty principle to show the possibility of generating weak photons in the microwave and RF range in such a way that it is impossible to measure the waveform generated by these photons without altering the waveform. The inherent problems of optical quantum systems show the advantages of this technique that includes: less range limitation, lower influence of environment and whether on the link, fast deployment and lower cost of equipments
{"title":"Wireless Qunatum-Key Distribution in RF and Microwave Frequencies","authors":"N. Jam, S. Khorsandi, M. Dehghan","doi":"10.1109/SPAWC.2006.346361","DOIUrl":"https://doi.org/10.1109/SPAWC.2006.346361","url":null,"abstract":"The uncertainty principle says that when elementary quantum systems like photons are used for information transmission, it is impossible in principle to eavesdrop on this media without a high probability of disturbing the transmission in such a way as to be detected. By this way we can make an absolutely secure communication link which can not be threaten by any kind of cheating by an opponent with unlimited computing power. Until now quantum transmission of digital information has been implemented using polarized photon transmission over dark fibers or optical wireless links mainly for random key distribution. In this paper we will use the same idea of uncertainty principle to show the possibility of generating weak photons in the microwave and RF range in such a way that it is impossible to measure the waveform generated by these photons without altering the waveform. The inherent problems of optical quantum systems show the advantages of this technique that includes: less range limitation, lower influence of environment and whether on the link, fast deployment and lower cost of equipments","PeriodicalId":414942,"journal":{"name":"2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130285345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-02DOI: 10.1109/SPAWC.2006.346440
Jun Liu, Xiangqian Liu
Recently an eigenvector-based algorithm has been developed for multidimensional frequency estimation. Unlike most existing algebraic approaches that estimate frequencies from eigenvalues, the eigenvector-based algorithm can achieve automatic frequency pairing without joint diagonalization of multiple matrices, but it is not applicable if there exist identical frequencies in certain dimensions. In this paper, we propose to use weighting factors to extend the eigenvector-based algorithm to handle identical frequencies in one or more dimensions. The weighting factors are optimized by minimizing the error variance. Simulation results demonstrate the effectiveness of the proposed approach
{"title":"Optimizing Eigenvector-Based Frequency Estimation in the Presence of Identical Frequencies in Multiple Dimensions","authors":"Jun Liu, Xiangqian Liu","doi":"10.1109/SPAWC.2006.346440","DOIUrl":"https://doi.org/10.1109/SPAWC.2006.346440","url":null,"abstract":"Recently an eigenvector-based algorithm has been developed for multidimensional frequency estimation. Unlike most existing algebraic approaches that estimate frequencies from eigenvalues, the eigenvector-based algorithm can achieve automatic frequency pairing without joint diagonalization of multiple matrices, but it is not applicable if there exist identical frequencies in certain dimensions. In this paper, we propose to use weighting factors to extend the eigenvector-based algorithm to handle identical frequencies in one or more dimensions. The weighting factors are optimized by minimizing the error variance. Simulation results demonstrate the effectiveness of the proposed approach","PeriodicalId":414942,"journal":{"name":"2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134253303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-02DOI: 10.1109/SPAWC.2006.346428
G. Mohammad-Khani, S. Lasaulce, J. Dumont
This paper describes a way of implementing DPC in a Gaussian MIMO broadcast channel. The outer encoder is based on a vector TCQ designed to possess certain "good properties". Simpler schemes such as the Tomlinson Harashima or scalar Costa's scheme are also considered by a way of comparison. The inner encoder is implemented through a vector version of the ZF-DPC and the MMSE-DPC. The BER performance of the DPC schemes is evaluated and compared to that of conventional interference cancellers (pre-ZF, pre-MMSE). From simulation results the choices of the inner encoder, the outer encoder (THS/SCS/TCQ) and the interference cancellation technique (conventional or DPC) are discussed
{"title":"About the Performance of Practical Dirty Paper Coding Schemes in Gaussian MIMO Broadcast Channels","authors":"G. Mohammad-Khani, S. Lasaulce, J. Dumont","doi":"10.1109/SPAWC.2006.346428","DOIUrl":"https://doi.org/10.1109/SPAWC.2006.346428","url":null,"abstract":"This paper describes a way of implementing DPC in a Gaussian MIMO broadcast channel. The outer encoder is based on a vector TCQ designed to possess certain \"good properties\". Simpler schemes such as the Tomlinson Harashima or scalar Costa's scheme are also considered by a way of comparison. The inner encoder is implemented through a vector version of the ZF-DPC and the MMSE-DPC. The BER performance of the DPC schemes is evaluated and compared to that of conventional interference cancellers (pre-ZF, pre-MMSE). From simulation results the choices of the inner encoder, the outer encoder (THS/SCS/TCQ) and the interference cancellation technique (conventional or DPC) are discussed","PeriodicalId":414942,"journal":{"name":"2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133977185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-02DOI: 10.1109/SPAWC.2006.346444
Á. Bravo, Antonio Artés-Rodríguez, P. Djurić
We present and analyze a packet combining strategy for wireless networks with slow Rayleigh fading. The scheme is based on adding the current signal-to-noise ratio (SNR) as an overhead to the packet and packet combining using the maximum a posteriori (MAP) criterion. We consider single and multiple wireless hops, and we perform comparisons against the optimum case, the maximum ratio combiner (MRC). For the single wireless hop, we show that the error probability curve is very close to the optimum. In addition, we study the effect of selection and an alternative based on averaging over the channel statistics that has poorer error performance, but needs less processing and overhead. In multiple wireless hops, some nodes act as relays and the error probability increases. However, combining several branches, each with two hops, allows for diversity order equal to the number of branches. We demonstrate the performance of the proposed strategy by computer simulations. The fusing packet scheme that is presented in this paper is adequate for sensor networks
{"title":"Packet Combining Over Rayleigh Channels using Signal-to-Noise Ratio Information and Detection by the Maximum A-Posteriori Criterion","authors":"Á. Bravo, Antonio Artés-Rodríguez, P. Djurić","doi":"10.1109/SPAWC.2006.346444","DOIUrl":"https://doi.org/10.1109/SPAWC.2006.346444","url":null,"abstract":"We present and analyze a packet combining strategy for wireless networks with slow Rayleigh fading. The scheme is based on adding the current signal-to-noise ratio (SNR) as an overhead to the packet and packet combining using the maximum a posteriori (MAP) criterion. We consider single and multiple wireless hops, and we perform comparisons against the optimum case, the maximum ratio combiner (MRC). For the single wireless hop, we show that the error probability curve is very close to the optimum. In addition, we study the effect of selection and an alternative based on averaging over the channel statistics that has poorer error performance, but needs less processing and overhead. In multiple wireless hops, some nodes act as relays and the error probability increases. However, combining several branches, each with two hops, allows for diversity order equal to the number of branches. We demonstrate the performance of the proposed strategy by computer simulations. The fusing packet scheme that is presented in this paper is adequate for sensor networks","PeriodicalId":414942,"journal":{"name":"2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications","volume":"202 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130725027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-02DOI: 10.1109/SPAWC.2006.346339
M. Khalighi, J. Hélard, S. Bourennane
We consider the use of MIMO structures in the fourth generation of cellular networks. We contrast the performances of the two general categories of orthogonal and non-orthogonal space-time schemes while considering a relatively simple iterative detector for the latter case. We show that with perfect channel knowledge, a substantial gain is obtained by using appropriate non-orthogonal schemes, which justifies the increased receiver complexity. The gain is more considerable for a larger number of transmit antennas. This conclusion remains true when channel estimation at receiver is not perfect
{"title":"Choice of Appropriate Space-Time Coding Scheme for MIMO Systems Employing Channel Coding under BICM","authors":"M. Khalighi, J. Hélard, S. Bourennane","doi":"10.1109/SPAWC.2006.346339","DOIUrl":"https://doi.org/10.1109/SPAWC.2006.346339","url":null,"abstract":"We consider the use of MIMO structures in the fourth generation of cellular networks. We contrast the performances of the two general categories of orthogonal and non-orthogonal space-time schemes while considering a relatively simple iterative detector for the latter case. We show that with perfect channel knowledge, a substantial gain is obtained by using appropriate non-orthogonal schemes, which justifies the increased receiver complexity. The gain is more considerable for a larger number of transmit antennas. This conclusion remains true when channel estimation at receiver is not perfect","PeriodicalId":414942,"journal":{"name":"2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134465384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-02DOI: 10.1109/SPAWC.2006.346492
P. Zhan, K. Yu, A. Swindlehurst
Herein, we investigate the optimal deployment of an unmanned aerial vehicle (UAV) in a wireless relay communication system. The optimal UAV position is found by maximizing the average data rate, while at the same time keeping the symbol error rate (SER) below a certain threshold. We derive a closed-form expression for the average data rate in a fixed wireless link using adaptive modulation. By using the alternate definite integral form for the Gaussian Q-function, the symbol error rate (SER) of the system in the link level is evaluated. An upper bound on the SER is also derived using the improved exponential bounds for the Q-function. It is shown that the derived SER expression matches the simulation results very well and the derived upper bound is tight for a wide range of SNRs. Simulation results also show that the system data rate matches the derived closed-form expression
{"title":"Wireless Relay Communications using ann Unmanned Aerial Vehicle","authors":"P. Zhan, K. Yu, A. Swindlehurst","doi":"10.1109/SPAWC.2006.346492","DOIUrl":"https://doi.org/10.1109/SPAWC.2006.346492","url":null,"abstract":"Herein, we investigate the optimal deployment of an unmanned aerial vehicle (UAV) in a wireless relay communication system. The optimal UAV position is found by maximizing the average data rate, while at the same time keeping the symbol error rate (SER) below a certain threshold. We derive a closed-form expression for the average data rate in a fixed wireless link using adaptive modulation. By using the alternate definite integral form for the Gaussian Q-function, the symbol error rate (SER) of the system in the link level is evaluated. An upper bound on the SER is also derived using the improved exponential bounds for the Q-function. It is shown that the derived SER expression matches the simulation results very well and the derived upper bound is tight for a wide range of SNRs. Simulation results also show that the system data rate matches the derived closed-form expression","PeriodicalId":414942,"journal":{"name":"2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114727125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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