Pub Date : 2013-06-18DOI: 10.1109/CWIT.2013.6621594
S. Asoodeh, F. Alajaji, T. Linder
The lossy source coding problem with feed-forward link was recently introduced in [1] and the corresponding rate-distortion function was derived in [2] and [3] for stationary and ergodic sources and for arbitrary sources with memory, respectively. The achievability schemes of [2] and [3] are mainly based on codetrees. In this work, we give an alternative proof of achievability for binary asymmetric Markov sources via a simple coding scheme that utilizes optimal lossy coding for Bernoulli sources. We then generalize this coding scheme for m-ary Markov sources and show its optimality for the distortion region where the Shannon lower bound is tight.
{"title":"An achievability proof for the lossy coding of Markov sources with feed-forward","authors":"S. Asoodeh, F. Alajaji, T. Linder","doi":"10.1109/CWIT.2013.6621594","DOIUrl":"https://doi.org/10.1109/CWIT.2013.6621594","url":null,"abstract":"The lossy source coding problem with feed-forward link was recently introduced in [1] and the corresponding rate-distortion function was derived in [2] and [3] for stationary and ergodic sources and for arbitrary sources with memory, respectively. The achievability schemes of [2] and [3] are mainly based on codetrees. In this work, we give an alternative proof of achievability for binary asymmetric Markov sources via a simple coding scheme that utilizes optimal lossy coding for Bernoulli sources. We then generalize this coding scheme for m-ary Markov sources and show its optimality for the distortion region where the Shannon lower bound is tight.","PeriodicalId":398936,"journal":{"name":"2013 13th Canadian Workshop on Information Theory","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115360548","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 : 2013-06-18DOI: 10.1109/CWIT.2013.6621598
Ahmed Medra, T. Davidson
We consider the three-cell MIMO interfering broadcast channel (IBC) with K users assigned to each base station. Each base station has M = 2K + 1 antennas and each user has N antennas. We propose two different linear precoding schemes to achieve the optimal degrees of freedom (DoF) for the case in which each user receives only one data stream. The first scheme finds the transmit precoders and receive beamformers using a sequence of closed-form steps that is initiated by the solution of an optimization problem on the Grassmannian manifold. One advantage of this scheme is the ability to achieve the optimal DoF with the minimum possible number of transmit and receive antennas. In the second scheme, the users in one cell will have additional K - 1 antennas, but we have been able a closed-form solution for each step of the generation of the transmit precoders and receive beamformers.
{"title":"On the achievability of the degrees of freedom for the three-cell MIMO interfering broadcast channel with minimum spatial dimensions","authors":"Ahmed Medra, T. Davidson","doi":"10.1109/CWIT.2013.6621598","DOIUrl":"https://doi.org/10.1109/CWIT.2013.6621598","url":null,"abstract":"We consider the three-cell MIMO interfering broadcast channel (IBC) with K users assigned to each base station. Each base station has M = 2K + 1 antennas and each user has N antennas. We propose two different linear precoding schemes to achieve the optimal degrees of freedom (DoF) for the case in which each user receives only one data stream. The first scheme finds the transmit precoders and receive beamformers using a sequence of closed-form steps that is initiated by the solution of an optimization problem on the Grassmannian manifold. One advantage of this scheme is the ability to achieve the optimal DoF with the minimum possible number of transmit and receive antennas. In the second scheme, the users in one cell will have additional K - 1 antennas, but we have been able a closed-form solution for each step of the generation of the transmit precoders and receive beamformers.","PeriodicalId":398936,"journal":{"name":"2013 13th Canadian Workshop on Information Theory","volume":"36 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114281135","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 : 2013-06-18DOI: 10.1109/CWIT.2013.6621606
H. E. Saffar, M. B. Khuzani, P. Mitran
We consider the problem of two-way lossy communication in an amplify-and-forward (AF) relay channel. Particularly, we study the problem in the case of communication between users with correlated Gaussian sources. First, we prove necessary conditions for achievability of a distortion tuple under a two-phase communication protocol. Then we study achievable schemes thorough separate source-channel coding and uncoded transmission. We derive the achievable distortion region and show that the separation scheme is optimal. In contrast to point-to-point communication where both schemes are optimal, here we further show that uncoded transmission fails to be optimal for correlated sources. However, for the special case of independent sources, uncoded transmission is also optimal. Eventually, we establish similar results for achievability of a distortion tuple in a three-phase communication protocol.
{"title":"Two-way lossy communication of correlated Gaussian sources with amplify-and-forward relaying","authors":"H. E. Saffar, M. B. Khuzani, P. Mitran","doi":"10.1109/CWIT.2013.6621606","DOIUrl":"https://doi.org/10.1109/CWIT.2013.6621606","url":null,"abstract":"We consider the problem of two-way lossy communication in an amplify-and-forward (AF) relay channel. Particularly, we study the problem in the case of communication between users with correlated Gaussian sources. First, we prove necessary conditions for achievability of a distortion tuple under a two-phase communication protocol. Then we study achievable schemes thorough separate source-channel coding and uncoded transmission. We derive the achievable distortion region and show that the separation scheme is optimal. In contrast to point-to-point communication where both schemes are optimal, here we further show that uncoded transmission fails to be optimal for correlated sources. However, for the special case of independent sources, uncoded transmission is also optimal. Eventually, we establish similar results for achievability of a distortion tuple in a three-phase communication protocol.","PeriodicalId":398936,"journal":{"name":"2013 13th Canadian Workshop on Information Theory","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121371967","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 : 2013-06-18DOI: 10.1109/CWIT.2013.6621602
G. Sridharan, Wei Yu
This paper investigates the significance of decomposition-based schemes in achieving the optimal degrees of freedom (DoF) of multiple-input multiple-output (MIMO) cellular networks. We consider MIMO cellular networks with G cells, K users/cell with M antennas at each user, and N antennas at each base-station (BS). We assume all channels to be generic and time varying. We show that KMN over KM + N DoF/cell can be achieved through one-sided decomposition of a MIMO cellular network (on the user side), followed by the use of an asymptotic interference alignment scheme. We then prove that such an approach achieves the optimal DoF whenever M over N = 1 over q, where equation. The optimality is proved using a new set of outer bounds on the DoF of a MIMO cellular network. Finally, we comment on the DoF achieved using two-sided decomposition, and the optimal DoF of cellular networks with single-antenna users and cellular networks with two cells.
本文研究了基于分解的方案在实现多输入多输出(MIMO)蜂窝网络的最优自由度(DoF)中的意义。我们考虑具有G个小区的MIMO蜂窝网络，每个小区有K个用户，每个用户有M个天线，每个基站(BS)有N个天线。我们假设所有的通道都是通用的和时变的。我们表明，通过对MIMO蜂窝网络(在用户侧)进行单边分解，然后使用渐近干扰对准方案，可以实现KM + N DoF/cell的KMN。然后，我们证明了当M / N = 1 / q时，这种方法达到了最优自由度，其中式。利用一组新的蜂窝MIMO网络的DoF外边界证明了该算法的最优性。最后，我们评论了使用双边分解获得的DoF，以及单天线用户蜂窝网络和双蜂窝网络的最优DoF。
{"title":"On achieving optimal degrees of freedom of MIMO cellular networks using decomposition","authors":"G. Sridharan, Wei Yu","doi":"10.1109/CWIT.2013.6621602","DOIUrl":"https://doi.org/10.1109/CWIT.2013.6621602","url":null,"abstract":"This paper investigates the significance of decomposition-based schemes in achieving the optimal degrees of freedom (DoF) of multiple-input multiple-output (MIMO) cellular networks. We consider MIMO cellular networks with G cells, K users/cell with M antennas at each user, and N antennas at each base-station (BS). We assume all channels to be generic and time varying. We show that KMN over KM + N DoF/cell can be achieved through one-sided decomposition of a MIMO cellular network (on the user side), followed by the use of an asymptotic interference alignment scheme. We then prove that such an approach achieves the optimal DoF whenever M over N = 1 over q, where equation. The optimality is proved using a new set of outer bounds on the DoF of a MIMO cellular network. Finally, we comment on the DoF achieved using two-sided decomposition, and the optimal DoF of cellular networks with single-antenna users and cellular networks with two cells.","PeriodicalId":398936,"journal":{"name":"2013 13th Canadian Workshop on Information Theory","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125810608","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 : 2013-06-18DOI: 10.1109/CWIT.2013.6621623
Hao Li, Xianbin Wang, Weikun Hou
A cooperative jamming system is investigated to enhance security of wireless communications in the presence of eavesdroppers. Different from traditional wireless security strategies that maximize secrecy capacity, a novel strategy based on the minimization of compromised secrecy region (CSR) is proposed. The secrecy region with a given secrecy outage probability is derived by considering path-loss and fading channel effects. Through numerical approximation of the outage probability, the optimal location and allocated power of the jammer are calculated to minimize the CSR which exhibits high secrecy outage probability. Without knowing the exact location of the randomly-distributed eavesdropper, our proposed scheme provides a new optimization criterion based on this compromised area minimization, thereby increasing the security level in cooperative jamming systems. Numerical results further validate the proposed CSR minimization scheme for cooperative jamming.
{"title":"Security enhancement in cooperative jamming using compromised secrecy region minimization","authors":"Hao Li, Xianbin Wang, Weikun Hou","doi":"10.1109/CWIT.2013.6621623","DOIUrl":"https://doi.org/10.1109/CWIT.2013.6621623","url":null,"abstract":"A cooperative jamming system is investigated to enhance security of wireless communications in the presence of eavesdroppers. Different from traditional wireless security strategies that maximize secrecy capacity, a novel strategy based on the minimization of compromised secrecy region (CSR) is proposed. The secrecy region with a given secrecy outage probability is derived by considering path-loss and fading channel effects. Through numerical approximation of the outage probability, the optimal location and allocated power of the jammer are calculated to minimize the CSR which exhibits high secrecy outage probability. Without knowing the exact location of the randomly-distributed eavesdropper, our proposed scheme provides a new optimization criterion based on this compromised area minimization, thereby increasing the security level in cooperative jamming systems. Numerical results further validate the proposed CSR minimization scheme for cooperative jamming.","PeriodicalId":398936,"journal":{"name":"2013 13th Canadian Workshop on Information Theory","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130264546","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 : 2013-06-18DOI: 10.1109/CWIT.2013.6621584
Ghady Azar, F. Alajaji
We study optimal maximum likelihood block decoding of binary codes sent over binary contagion channels with infinite and finite memory. We derive conditions on the codes and channels parameters under which maximum likelihood and minimum Hamming distance are equivalent. We also note that under these conditions, minimum distance decoding can perform better without the use of channel interleaving.
{"title":"When are maximum likelihood and minimum distance decoding equivalent for binary contagion channels?","authors":"Ghady Azar, F. Alajaji","doi":"10.1109/CWIT.2013.6621584","DOIUrl":"https://doi.org/10.1109/CWIT.2013.6621584","url":null,"abstract":"We study optimal maximum likelihood block decoding of binary codes sent over binary contagion channels with infinite and finite memory. We derive conditions on the codes and channels parameters under which maximum likelihood and minimum Hamming distance are equivalent. We also note that under these conditions, minimum distance decoding can perform better without the use of channel interleaving.","PeriodicalId":398936,"journal":{"name":"2013 13th Canadian Workshop on Information Theory","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130449877","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 : 2013-06-18DOI: 10.1109/CWIT.2013.6621605
R. Devarajan, Shankhanaad Mallick, V. Bhargava
We consider an interference limited heterogeneous cellular network, where co-channel macro and femto cells coexist. We focus on the downlink transmission, where a macro base station (MBS) communicates with a macro user equipment (MUE) via a macro relay station (MRS), whereas femto base stations (FBS) communicate with femto user equipments (FUE) directly. We propose centralized power allocation schemes to optimally allocate power among the MBS, MRS and FBSs. The power allocation schemes consider the difference in the significance of macro and femto networks by assigning different importance levels. Then, we discuss a distributed approach, where each cell can independently and separately optimize its own downlink transmission power. Numerical results indicate the effectiveness and performance of our schemes.
{"title":"Power allocation schemes for relay-based heterogeneous networks","authors":"R. Devarajan, Shankhanaad Mallick, V. Bhargava","doi":"10.1109/CWIT.2013.6621605","DOIUrl":"https://doi.org/10.1109/CWIT.2013.6621605","url":null,"abstract":"We consider an interference limited heterogeneous cellular network, where co-channel macro and femto cells coexist. We focus on the downlink transmission, where a macro base station (MBS) communicates with a macro user equipment (MUE) via a macro relay station (MRS), whereas femto base stations (FBS) communicate with femto user equipments (FUE) directly. We propose centralized power allocation schemes to optimally allocate power among the MBS, MRS and FBSs. The power allocation schemes consider the difference in the significance of macro and femto networks by assigning different importance levels. Then, we discuss a distributed approach, where each cell can independently and separately optimize its own downlink transmission power. Numerical results indicate the effectiveness and performance of our schemes.","PeriodicalId":398936,"journal":{"name":"2013 13th Canadian Workshop on Information Theory","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117262011","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}
We investigate a constant-power, variable-rate multiple-input multiple-output adaptive subcarrier intensity modulation employing rectangular quadrature amplitude modulation for optical wireless communication over the Gamma-Gamma turbulence channels. The adaptive scheme is implemented by adapting the modulation order according to the received signal-to-noise ratio and a pre-defined target bit-error rate requirement. Novel closed-form expressions for the achievable spectral efficiency, average bit-error rate, and outage probability are presented in terms of a fast convergent infinite series. In addition, asymptotic bit-error rate and outage probability analyses are presented. Our asymptotic analysis reveals that the diversity order of the considered multiple-input multiple-output system depends on the number of transmit and receive apertures, and on the smaller channel parameter of the Gamma-Gamma turbulence.
{"title":"Performance of MIMO adaptive subcarrier QAM intensity modulation in Gamma-Gamma turbulence","authors":"Md. Zoheb Hassan, Md. Jahangir Hossain, Julian Cheng","doi":"10.1109/CWIT.2013.6621619","DOIUrl":"https://doi.org/10.1109/CWIT.2013.6621619","url":null,"abstract":"We investigate a constant-power, variable-rate multiple-input multiple-output adaptive subcarrier intensity modulation employing rectangular quadrature amplitude modulation for optical wireless communication over the Gamma-Gamma turbulence channels. The adaptive scheme is implemented by adapting the modulation order according to the received signal-to-noise ratio and a pre-defined target bit-error rate requirement. Novel closed-form expressions for the achievable spectral efficiency, average bit-error rate, and outage probability are presented in terms of a fast convergent infinite series. In addition, asymptotic bit-error rate and outage probability analyses are presented. Our asymptotic analysis reveals that the diversity order of the considered multiple-input multiple-output system depends on the number of transmit and receive apertures, and on the smaller channel parameter of the Gamma-Gamma turbulence.","PeriodicalId":398936,"journal":{"name":"2013 13th Canadian Workshop on Information Theory","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115440182","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 : 2013-06-18DOI: 10.1109/CWIT.2013.6621592
Yinghan Wan, S. Dumitrescu
This work is concerned with increasing the error resilience of two description scalar quantizers by applying a permutation to the index of each description, for an m-diagonal initial index assignment. First we address the existence of permutations achieving a minimum Hamming distance of at least 2. Such permutations allow the central decoder to detect any 1 bit error pattern. We establish the connection with the hypercube antibandwidth problem, connection which allows us to determine the highest value of m for which such a permutation exists and to show its construction. Further, we highlight the relation between the error robustness at the side decoders and the bandwidth of the hypercube labeling associated to the permutation. To ensure error resilience at both the central and side decoders we are interested in labelings with the lowest bandwidth given that the antibandwidth is larger or equal to m. We make some progress toward the solution of this problem by constructing a class of hypercube labelings trading the increase in antibandwidth for the decrease in bandwidth.
{"title":"Index assignment capable of detecting one bit errors for multiple description scalar quantizers","authors":"Yinghan Wan, S. Dumitrescu","doi":"10.1109/CWIT.2013.6621592","DOIUrl":"https://doi.org/10.1109/CWIT.2013.6621592","url":null,"abstract":"This work is concerned with increasing the error resilience of two description scalar quantizers by applying a permutation to the index of each description, for an m-diagonal initial index assignment. First we address the existence of permutations achieving a minimum Hamming distance of at least 2. Such permutations allow the central decoder to detect any 1 bit error pattern. We establish the connection with the hypercube antibandwidth problem, connection which allows us to determine the highest value of m for which such a permutation exists and to show its construction. Further, we highlight the relation between the error robustness at the side decoders and the bandwidth of the hypercube labeling associated to the permutation. To ensure error resilience at both the central and side decoders we are interested in labelings with the lowest bandwidth given that the antibandwidth is larger or equal to m. We make some progress toward the solution of this problem by constructing a class of hypercube labelings trading the increase in antibandwidth for the decrease in bandwidth.","PeriodicalId":398936,"journal":{"name":"2013 13th Canadian Workshop on Information Theory","volume":"203 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122415472","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 : 2013-06-18DOI: 10.1109/CWIT.2013.6621607
M. R. Avendi, Ha H. Nguyen
This paper studies dual-hop amplify-and-forward relaying over time-varying Rayleigh fading channels with differential M-PSK modulation and non-coherent detection. For the case of “two-symbol” detection, a first order time-series model is utilized to characterize the time-varying nature of the cascaded channel. Based on this model, an exact bit error rate (BER) expression is derived and confirmed with simulation results. The obtained expression shows that the BER is related to the auto-correlation of the cascaded channel and an irreducible error floor exists at high transmit power. To overcome the error floor experienced with fast-fading, a nearly optimal “multiple-symbol” differential sphere detection (MSDSD) is also developed. The error performance of MSDSD is illustrated with simulation results under different fading scenarios.
{"title":"Differential dual-hop relaying over time-varying Rayleigh-fading channels","authors":"M. R. Avendi, Ha H. Nguyen","doi":"10.1109/CWIT.2013.6621607","DOIUrl":"https://doi.org/10.1109/CWIT.2013.6621607","url":null,"abstract":"This paper studies dual-hop amplify-and-forward relaying over time-varying Rayleigh fading channels with differential M-PSK modulation and non-coherent detection. For the case of “two-symbol” detection, a first order time-series model is utilized to characterize the time-varying nature of the cascaded channel. Based on this model, an exact bit error rate (BER) expression is derived and confirmed with simulation results. The obtained expression shows that the BER is related to the auto-correlation of the cascaded channel and an irreducible error floor exists at high transmit power. To overcome the error floor experienced with fast-fading, a nearly optimal “multiple-symbol” differential sphere detection (MSDSD) is also developed. The error performance of MSDSD is illustrated with simulation results under different fading scenarios.","PeriodicalId":398936,"journal":{"name":"2013 13th Canadian Workshop on Information Theory","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127882476","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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