Pub Date : 2011-05-17DOI: 10.1109/CWIT.2011.5872136
S. M. Aghajanzadeh, M. Uysal
In this paper, we investigate the diversity-multiplexing tradeoff (DMT) of a multi-hop coherent free-space optical (FSO) system over atmospheric channels. We consider a relay-assisted FSO system with decode-and-forward relay nodes and multiple heterodyne receivers with modal compensation. Based on a recently introduced statistical characterization for the combined effects of turbulence-induced amplitude fluctuations and phase aberrations, we quantify the potential performance improvements through the derivation of DMT. Our results demonstrate significant performance gains that can be achieved by multi-hop transmission in coherent FSO systems.
{"title":"DMT analysis of multi-hop coherent FSO communication over atmospheric channels","authors":"S. M. Aghajanzadeh, M. Uysal","doi":"10.1109/CWIT.2011.5872136","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872136","url":null,"abstract":"In this paper, we investigate the diversity-multiplexing tradeoff (DMT) of a multi-hop coherent free-space optical (FSO) system over atmospheric channels. We consider a relay-assisted FSO system with decode-and-forward relay nodes and multiple heterodyne receivers with modal compensation. Based on a recently introduced statistical characterization for the combined effects of turbulence-induced amplitude fluctuations and phase aberrations, we quantify the potential performance improvements through the derivation of DMT. Our results demonstrate significant performance gains that can be achieved by multi-hop transmission in coherent FSO systems.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115360811","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872133
Mansoor I. Yousefi, F. Kschischang
The capacity of the channel defined by the stochastic nonlinear Schrödinger equation, which includes the effects of the Kerr nonlinearity and amplified spontaneous emission noise, is considered in the case of zero dispersion. For the first time, the exact capacity subject to peak and average power constraints is numerically quantified using dense multiple ring modulation formats. It is shown that, for a fixed noise power, the per-sample capacity grows unbounded with input signal power. A distribution with a half-Gaussian profile on amplitude and uniform phase is shown to provide a lower bound to the capacity which is simple and asymptotically optimal at high SNRs.
{"title":"The per-sample capacity of zero-dispersion optical fibers","authors":"Mansoor I. Yousefi, F. Kschischang","doi":"10.1109/CWIT.2011.5872133","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872133","url":null,"abstract":"The capacity of the channel defined by the stochastic nonlinear Schrödinger equation, which includes the effects of the Kerr nonlinearity and amplified spontaneous emission noise, is considered in the case of zero dispersion. For the first time, the exact capacity subject to peak and average power constraints is numerically quantified using dense multiple ring modulation formats. It is shown that, for a fixed noise power, the per-sample capacity grows unbounded with input signal power. A distribution with a half-Gaussian profile on amplitude and uniform phase is shown to provide a lower bound to the capacity which is simple and asymptotically optimal at high SNRs.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128101528","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872157
D. W. K. Ng, R. Schober
In this paper, we formulate an optimization problem for resource allocation and scheduling in orthogonal frequency division multiple access (OFDMA) half-duplex decode-and-forward (DF) relay assisted networks. Our problem formulation takes into account artificial noise generation to combat a multiple antenna eavesdropper. The secrecy data rate, power, and sub-carrier allocation policies are optimized to maximize the average secrecy outage capacity (bit/s/Hz securely delivered to the users via relays). The optimization problem is solved by dual decomposition which results in an efficient iterative algorithm. Simulation results illustrate that the proposed iterative algorithm converges in a small number of iterations and guarantees a non-zero secrecy date rate for a given target secrecy outage probability.
{"title":"Resource allocation for secure OFDMA decode-and-forward relay networks","authors":"D. W. K. Ng, R. Schober","doi":"10.1109/CWIT.2011.5872157","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872157","url":null,"abstract":"In this paper, we formulate an optimization problem for resource allocation and scheduling in orthogonal frequency division multiple access (OFDMA) half-duplex decode-and-forward (DF) relay assisted networks. Our problem formulation takes into account artificial noise generation to combat a multiple antenna eavesdropper. The secrecy data rate, power, and sub-carrier allocation policies are optimized to maximize the average secrecy outage capacity (bit/s/Hz securely delivered to the users via relays). The optimization problem is solved by dual decomposition which results in an efficient iterative algorithm. Simulation results illustrate that the proposed iterative algorithm converges in a small number of iterations and guarantees a non-zero secrecy date rate for a given target secrecy outage probability.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132510207","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872160
R. Devarajan, S. C. Jha, Umesh Phuyal, V. Bhargava
Energy consumption in wireless communication system is rapidly increasing due to the growth in wireless multimedia access. Combating the adverse effects of excessive energy consumption demands for energy-aware system design called green communication, which has become the major focus of many researchers recently. In this paper, we propose user selection and power allocation schemes for a multi-user multi-relay cooperative cellular system in order to minimize the cost of transmission. In the proposed schemes, the cost function is first formulated with the objective of optimizing the sum power consumption. Then it is extended to a more general multi-objective optimization scheme which jointly optimizes the sum power and throughput. The former scheme makes the system energy efficient, while the latter scheme keeps a balance between energy efficiency and throughput. In both of the schemes, quality-of-service is guaranteed in terms of end-to-end signal-to-noise ratio. Numerical results are also presented to confirm the system performance enhancement with the proposed schemes.
{"title":"Energy-aware user selection and power allocation for cooperative communication system with guaranteed quality-of-service","authors":"R. Devarajan, S. C. Jha, Umesh Phuyal, V. Bhargava","doi":"10.1109/CWIT.2011.5872160","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872160","url":null,"abstract":"Energy consumption in wireless communication system is rapidly increasing due to the growth in wireless multimedia access. Combating the adverse effects of excessive energy consumption demands for energy-aware system design called green communication, which has become the major focus of many researchers recently. In this paper, we propose user selection and power allocation schemes for a multi-user multi-relay cooperative cellular system in order to minimize the cost of transmission. In the proposed schemes, the cost function is first formulated with the objective of optimizing the sum power consumption. Then it is extended to a more general multi-objective optimization scheme which jointly optimizes the sum power and throughput. The former scheme makes the system energy efficient, while the latter scheme keeps a balance between energy efficiency and throughput. In both of the schemes, quality-of-service is guaranteed in terms of end-to-end signal-to-noise ratio. Numerical results are also presented to confirm the system performance enhancement with the proposed schemes.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132652121","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872130
Andrew Liau, S. Yousefi, Il Kim
For the binary erasure channel, Luby Transform (LT) and Raptors codes have been shown to achieve capacity by carefully designed degree distributions for multicasting scenarios. Generalizing fountain codes to multihop networks requires transport nodes to perform network coding (NC). However, if intermediate nodes perform decentralized NC blindly, the statistical properties imposed by the fountain code are lost, and thus, a Gaussian elimination decoder must be used at the sink at the cost of significant increase in complexity compared to a belief propagation (BP) decoder. Addressing this problem, in this paper, we propose a new protocol, namely Soliton-like rateless coding (SLRC), by exploiting the benefits of fountain coding and NC coding over a Y-network. Ensuring key properties of the fountain code are preserved, BP can be effectively applied when transport nodes perform NC. The SLRC scheme is evaluated against buffer-and-forwarding, and other state of the art schemes; SLRC exhibits a 5% reduction in overhead at high decoding success rates. Simulations show that the proposed scheme preserves the benefits of NC and fountain coding.
{"title":"Soliton-like network coding for a single relay","authors":"Andrew Liau, S. Yousefi, Il Kim","doi":"10.1109/CWIT.2011.5872130","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872130","url":null,"abstract":"For the binary erasure channel, Luby Transform (LT) and Raptors codes have been shown to achieve capacity by carefully designed degree distributions for multicasting scenarios. Generalizing fountain codes to multihop networks requires transport nodes to perform network coding (NC). However, if intermediate nodes perform decentralized NC blindly, the statistical properties imposed by the fountain code are lost, and thus, a Gaussian elimination decoder must be used at the sink at the cost of significant increase in complexity compared to a belief propagation (BP) decoder. Addressing this problem, in this paper, we propose a new protocol, namely Soliton-like rateless coding (SLRC), by exploiting the benefits of fountain coding and NC coding over a Y-network. Ensuring key properties of the fountain code are preserved, BP can be effectively applied when transport nodes perform NC. The SLRC scheme is evaluated against buffer-and-forwarding, and other state of the art schemes; SLRC exhibits a 5% reduction in overhead at high decoding success rates. Simulations show that the proposed scheme preserves the benefits of NC and fountain coding.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129846931","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872126
A. Saleh, F. Alajaji, W. Chan
We consider the problem of bandwidth expansion for lossy joint source-channel coding over a memoryless Gaussian channel. A low delay 1∶3 bandwidth expansion hybrid digital-analog coding system, which combines a scalar quantizer and a 1∶2 nonlinear analog coder, is proposed. It is shown that our proposed system outperforms the 1∶3 generalized hybrid scalar quantizer linear coder in terms of signal-to-distortion ratio (SDR). A lower bound on the system SDR is also derived.
{"title":"Hybrid digital-analog source-channel coding with one-to-three bandwidth expansion","authors":"A. Saleh, F. Alajaji, W. Chan","doi":"10.1109/CWIT.2011.5872126","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872126","url":null,"abstract":"We consider the problem of bandwidth expansion for lossy joint source-channel coding over a memoryless Gaussian channel. A low delay 1∶3 bandwidth expansion hybrid digital-analog coding system, which combines a scalar quantizer and a 1∶2 nonlinear analog coder, is proposed. It is shown that our proposed system outperforms the 1∶3 generalized hybrid scalar quantizer linear coder in terms of signal-to-distortion ratio (SDR). A lower bound on the system SDR is also derived.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127083429","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872118
M. Mirmohseni, Bahareh Akhbari, M. Aref
In this paper, we consider a three-user cognitive radio network with two primary users and one cognitive radio. We concentrate on a three-user Interference Channel (IFC) where one of the transmitters has cognitive capabilities and non-causally knows the messages of the other two transmitters. Moreover, we assume that the cognitive transmitter does not cause any interference at the receivers of the primary users and we introduce three-user Cognitive Z-Interference Channel (C-ZIFC). We first obtain an inner bound on the capacity region of three-user C-ZIFC, where our coding scheme makes use of collaborative strategy by rate splitting and cooperative strategy by superposition coding. Moreover, the cognitive user uses Gel'fand-Pinsker binning in order to reduce the interference at its own receiver. We also provide an outer bound on the capacity region of this channel and show that characterizing the capacity region of a three-user C-ZIFC is non-trivial based on the two-user case; the reason lies in the fact that the three-user setup captures the specifications of the IFC like independent channel inputs. We also consider the Gaussian case and find an achievable rate region for the Gaussian C-ZIFC.
{"title":"Capacity bounds for the three-user Cognitive Z-Interference Channel","authors":"M. Mirmohseni, Bahareh Akhbari, M. Aref","doi":"10.1109/CWIT.2011.5872118","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872118","url":null,"abstract":"In this paper, we consider a three-user cognitive radio network with two primary users and one cognitive radio. We concentrate on a three-user Interference Channel (IFC) where one of the transmitters has cognitive capabilities and non-causally knows the messages of the other two transmitters. Moreover, we assume that the cognitive transmitter does not cause any interference at the receivers of the primary users and we introduce three-user Cognitive Z-Interference Channel (C-ZIFC). We first obtain an inner bound on the capacity region of three-user C-ZIFC, where our coding scheme makes use of collaborative strategy by rate splitting and cooperative strategy by superposition coding. Moreover, the cognitive user uses Gel'fand-Pinsker binning in order to reduce the interference at its own receiver. We also provide an outer bound on the capacity region of this channel and show that characterizing the capacity region of a three-user C-ZIFC is non-trivial based on the two-user case; the reason lies in the fact that the three-user setup captures the specifications of the IFC like independent channel inputs. We also consider the Gaussian case and find an achievable rate region for the Gaussian C-ZIFC.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121995973","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872147
S. Dhakal, A. Bayesteh
Sparse space codes (SSC) are proposed as a novel transmission scheme for an under-determined MIMO channel. Each SSC codeword is a sparse vector of the size of the number of transmit antennas. The information is imparted through: (i) uncertainty in the positions of non-zero elements, and (ii) uncertainty in the symbol-space of non-zero elements. Basis-pursuit (BPD) and LASSO detectors are used with knowledge of code sparsity to detect SSC. However, their performance is found to be degraded compared to the Maximum Likelihood Detector (MLD). A runner-up basis pursuit algorithm is proposed that provides MLD-like performance with a small increment in complexity over BPD. Analytical and simulation results show that SSC outperforms orthogonal space time block codes in terms of word error rate at varying SNR ranges.
{"title":"Sparse space codes for multi-antenna systems","authors":"S. Dhakal, A. Bayesteh","doi":"10.1109/CWIT.2011.5872147","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872147","url":null,"abstract":"Sparse space codes (SSC) are proposed as a novel transmission scheme for an under-determined MIMO channel. Each SSC codeword is a sparse vector of the size of the number of transmit antennas. The information is imparted through: (i) uncertainty in the positions of non-zero elements, and (ii) uncertainty in the symbol-space of non-zero elements. Basis-pursuit (BPD) and LASSO detectors are used with knowledge of code sparsity to detect SSC. However, their performance is found to be degraded compared to the Maximum Likelihood Detector (MLD). A runner-up basis pursuit algorithm is proposed that provides MLD-like performance with a small increment in complexity over BPD. Analytical and simulation results show that SSC outperforms orthogonal space time block codes in terms of word error rate at varying SNR ranges.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114080542","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872142
Todd D. Mateer
Dornstetter, Heydtmann, and Jensen have previously demonstrated that the Extended Euclidean algorithm and the Berlekamp-Massey algorithm are two equivalent methods used for solving the so-called Key Equation in BCH and Reed-Solomon decoding. This paper presents a new algorithm which makes this correspondence more explicit and is an improvement over each of the two algorithms.
{"title":"On the equivalence of the Berlekamp-Massey and the euclidean algorithms for algebraic decoding","authors":"Todd D. Mateer","doi":"10.1109/CWIT.2011.5872142","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872142","url":null,"abstract":"Dornstetter, Heydtmann, and Jensen have previously demonstrated that the Extended Euclidean algorithm and the Berlekamp-Massey algorithm are two equivalent methods used for solving the so-called Key Equation in BCH and Reed-Solomon decoding. This paper presents a new algorithm which makes this correspondence more explicit and is an improvement over each of the two algorithms.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116944209","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 : 2011-04-04DOI: 10.1109/CWIT.2011.5872121
C. Senger, V. Sidorenko, Steffen Schober, M. Bossert, V. Zyablov
Algebraic decoding algorithms are commonly applied for the decoding of Reed-Solomon codes. Their main advantages are low computational complexity and predictable decoding capabilities. Many algorithms can be extended for correction of both errors and erasures. This enables the decoder to exploit binary quantized reliability information obtained from the transmission channel: Received symbols with high reliability are forwarded to the decoding algorithm while symbols with low reliability are erased. In this paper we investigate adaptive single-trial error/erasure decoding of Reed-Solomon codes, i.e. we derive an adaptive erasing strategy which minimizes the residual codeword error probability after decoding. Our result is applicable to any error/erasure decoding algorithm as long as its decoding capabilities can be expressed by a decoder capability function. Examples are Bounded Minimum Distance decoding with the Berlekamp-Massey- or the Sugiyama algorithms and the Guruswami-Sudan list decoder.
{"title":"Adaptive single-trial error/erasure decoding of Reed-Solomon codes","authors":"C. Senger, V. Sidorenko, Steffen Schober, M. Bossert, V. Zyablov","doi":"10.1109/CWIT.2011.5872121","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872121","url":null,"abstract":"Algebraic decoding algorithms are commonly applied for the decoding of Reed-Solomon codes. Their main advantages are low computational complexity and predictable decoding capabilities. Many algorithms can be extended for correction of both errors and erasures. This enables the decoder to exploit binary quantized reliability information obtained from the transmission channel: Received symbols with high reliability are forwarded to the decoding algorithm while symbols with low reliability are erased. In this paper we investigate adaptive single-trial error/erasure decoding of Reed-Solomon codes, i.e. we derive an adaptive erasing strategy which minimizes the residual codeword error probability after decoding. Our result is applicable to any error/erasure decoding algorithm as long as its decoding capabilities can be expressed by a decoder capability function. Examples are Bounded Minimum Distance decoding with the Berlekamp-Massey- or the Sugiyama algorithms and the Guruswami-Sudan list decoder.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121973924","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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