Pub Date : 2017-03-06DOI: 10.1109/DySPAN.2017.7920793
Sudeep Bhattarai, J. Park, W. Lehr, Bo Gao
Radio propagation models play a crucial role in realizing effective spectrum sharing. Unlike propagation models that do not use the exact details of terrain, terrain-based propagation models are effective in identifying spatial spectrum sharing opportunities for the secondary users (SUs) around an incumbent user (IU). Unfortunately, terrain-based propagation models, such as the Irregular Terrain Model (ITM) in point-to-point (PTP) mode, are computationally expensive, and they require precise geo-locations of the SUs. Such requirements render them challenging, if not impractical, to implement in real-time applications, such as geolocation database (GDB)-driven spectrum sharing. To address this problem, we propose a pragmatic approach called Tool for Enabling Spatial Spectrum Sharing Opportunities (TESSO). TESSO characterizes the aggregate interference caused by the SUs and identifies spatial spectrum sharing opportunities effectively. It is computationally efficient, and does not require precise geo-locations of the SUs. Our results show that TESSO provides the same level of interference protection guarantee to the IU as that offered by the terrain-based models. TESSO can be implemented in GDB-driven spectrum sharing ecosystems for effectively exploiting spatial spectrum sharing opportunities.
{"title":"TESSO: An analytical tool for characterizing aggregate interference and enabling spatial spectrum sharing","authors":"Sudeep Bhattarai, J. Park, W. Lehr, Bo Gao","doi":"10.1109/DySPAN.2017.7920793","DOIUrl":"https://doi.org/10.1109/DySPAN.2017.7920793","url":null,"abstract":"Radio propagation models play a crucial role in realizing effective spectrum sharing. Unlike propagation models that do not use the exact details of terrain, terrain-based propagation models are effective in identifying spatial spectrum sharing opportunities for the secondary users (SUs) around an incumbent user (IU). Unfortunately, terrain-based propagation models, such as the Irregular Terrain Model (ITM) in point-to-point (PTP) mode, are computationally expensive, and they require precise geo-locations of the SUs. Such requirements render them challenging, if not impractical, to implement in real-time applications, such as geolocation database (GDB)-driven spectrum sharing. To address this problem, we propose a pragmatic approach called Tool for Enabling Spatial Spectrum Sharing Opportunities (TESSO). TESSO characterizes the aggregate interference caused by the SUs and identifies spatial spectrum sharing opportunities effectively. It is computationally efficient, and does not require precise geo-locations of the SUs. Our results show that TESSO provides the same level of interference protection guarantee to the IU as that offered by the terrain-based models. TESSO can be implemented in GDB-driven spectrum sharing ecosystems for effectively exploiting spatial spectrum sharing opportunities.","PeriodicalId":221877,"journal":{"name":"2017 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126165450","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 : 2017-03-06DOI: 10.1109/DySPAN.2017.7920762
T. Vermeulen, M. Laghate, Ghaith Hattab, B. V. Liempd, D. Cabric, S. Pollin
In wireless communication it is assumed that transmitting nodes are unable to detect collisions. However, using recent advances in in-band full duplex, a system can be developed where the self-transmitted signal is sufficiently canceled in order to detect ongoing collisions. Enabling concurrent transmission and collision detection can greatly improve wireless communication by enhancing throughput and decreasing delay and energy consumption. For this demo, we implemented a real-time collision and interference detection algorithm on the FPGA of a USRP. Inband full duplex is enabled using an electrical balance duplexer. A second USRP is used to generate interfering signals on demand.
{"title":"Nearly instantaneous collision and interference detection using in-band full duplex","authors":"T. Vermeulen, M. Laghate, Ghaith Hattab, B. V. Liempd, D. Cabric, S. Pollin","doi":"10.1109/DySPAN.2017.7920762","DOIUrl":"https://doi.org/10.1109/DySPAN.2017.7920762","url":null,"abstract":"In wireless communication it is assumed that transmitting nodes are unable to detect collisions. However, using recent advances in in-band full duplex, a system can be developed where the self-transmitted signal is sufficiently canceled in order to detect ongoing collisions. Enabling concurrent transmission and collision detection can greatly improve wireless communication by enhancing throughput and decreasing delay and energy consumption. For this demo, we implemented a real-time collision and interference detection algorithm on the FPGA of a USRP. Inband full duplex is enabled using an electrical balance duplexer. A second USRP is used to generate interfering signals on demand.","PeriodicalId":221877,"journal":{"name":"2017 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131093480","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 : 2017-03-06DOI: 10.1109/DySPAN.2017.7920751
M. Laghate, D. Cabric
In this work, we study the wideband sensing problem of detecting intermittently transmitting signals that may have partial spectral overlap. We aim to estimate the frequency bands occupied by transmitters using standards with overlapping frequency bands, such as IEEE 802.11, and those without guard bands, such as LTE-Advanced. Multiple power spectrum measurements are used to distinguish the distinct bands. An extreme ray based non-negative matrix factorization algorithm is proposed to identify measurements where a single transmitter is active. Distinct bands are identified in the presence of frequency-selective fading by using a combinatorial search. In addition, we propose a novel algorithm to automatically estimate the noise power spectrum by identifying measurements that do not have significant signal energy. Its ability to learn colored noise and LO leakage in the signal is demonstrated through USRP measurements. The dependence of the proposed algorithm's performance on the medium access control protocol used by the primary users is discussed. MATLAB simulations are used to verify that the proposed algorithm detects the occupied bands more accurately than existing methods. Over the air USRP measurements in the 2.4 GHz ISM band are used to detect the occupied WiFi channels in a university environment.
{"title":"Using multiple power spectrum measurements to sense signals with partial spectral overlap","authors":"M. Laghate, D. Cabric","doi":"10.1109/DySPAN.2017.7920751","DOIUrl":"https://doi.org/10.1109/DySPAN.2017.7920751","url":null,"abstract":"In this work, we study the wideband sensing problem of detecting intermittently transmitting signals that may have partial spectral overlap. We aim to estimate the frequency bands occupied by transmitters using standards with overlapping frequency bands, such as IEEE 802.11, and those without guard bands, such as LTE-Advanced. Multiple power spectrum measurements are used to distinguish the distinct bands. An extreme ray based non-negative matrix factorization algorithm is proposed to identify measurements where a single transmitter is active. Distinct bands are identified in the presence of frequency-selective fading by using a combinatorial search. In addition, we propose a novel algorithm to automatically estimate the noise power spectrum by identifying measurements that do not have significant signal energy. Its ability to learn colored noise and LO leakage in the signal is demonstrated through USRP measurements. The dependence of the proposed algorithm's performance on the medium access control protocol used by the primary users is discussed. MATLAB simulations are used to verify that the proposed algorithm detects the occupied bands more accurately than existing methods. Over the air USRP measurements in the 2.4 GHz ISM band are used to detect the occupied WiFi channels in a university environment.","PeriodicalId":221877,"journal":{"name":"2017 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129286788","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 : 2017-03-06DOI: 10.1109/DySPAN.2017.7920761
M. Laghate, D. Cabric
Wideband spectrum sensing aims to identify the occupied frequency bands. Conventional methods for single antenna spectrum sensors threshold the received power spectra to detect discrete frequency bins that are occupied. However, such methods neither group bins that are occupied by the same signal nor aggregate occupied bins over time to learn distinct frequency bands occupied by intermittently transmitting signals. This paper demonstrates a method to learn the frequency bands occupied by intermittently transmitting incumbent radios that occupy adjacent frequency bands without a guard band, such as by LTE-Advanced, or are spectrally overlapping, such as by IEEE 802.11. It formulates the wideband sensing problem as the factorization of a matrix consisting of multiple power spectrum measurements. A novel extreme ray based non-negative matrix factorization algorithm estimates the noise power spectrum and also determines the received power spectrum of the incumbent radios. Energy detection and a combinatorial algorithm is used to determine the unique supports of the received signals. Using a USRP N210 software defined radio as a receiver, we demonstrate that this algorithm can determine the frequency bands occupied by nearby transmitters in the 2.4GHz ISM band. Furthermore, we demonstrate that the algorithm learns the power spectrum of the colored noise experienced by the USRP.
{"title":"Demonstrating spectrum sensing in colored noise for signals with partial spectral overlap","authors":"M. Laghate, D. Cabric","doi":"10.1109/DySPAN.2017.7920761","DOIUrl":"https://doi.org/10.1109/DySPAN.2017.7920761","url":null,"abstract":"Wideband spectrum sensing aims to identify the occupied frequency bands. Conventional methods for single antenna spectrum sensors threshold the received power spectra to detect discrete frequency bins that are occupied. However, such methods neither group bins that are occupied by the same signal nor aggregate occupied bins over time to learn distinct frequency bands occupied by intermittently transmitting signals. This paper demonstrates a method to learn the frequency bands occupied by intermittently transmitting incumbent radios that occupy adjacent frequency bands without a guard band, such as by LTE-Advanced, or are spectrally overlapping, such as by IEEE 802.11. It formulates the wideband sensing problem as the factorization of a matrix consisting of multiple power spectrum measurements. A novel extreme ray based non-negative matrix factorization algorithm estimates the noise power spectrum and also determines the received power spectrum of the incumbent radios. Energy detection and a combinatorial algorithm is used to determine the unique supports of the received signals. Using a USRP N210 software defined radio as a receiver, we demonstrate that this algorithm can determine the frequency bands occupied by nearby transmitters in the 2.4GHz ISM band. Furthermore, we demonstrate that the algorithm learns the power spectrum of the colored noise experienced by the USRP.","PeriodicalId":221877,"journal":{"name":"2017 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN)","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124298286","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 : 2017-03-06DOI: 10.1109/DySPAN.2017.7920744
C. Spooner, A. Mody, J. Chuang, Josh Petersen
We sketch the components of a system designed to compete in the Battle of the ModRecs Workshop at DySPAN 2017. The core ideas are the use of a flexible channelized receiver for obtaining the complex envelopes of variable-bandwidth bands-of-interest and the use of the spectral correlation function (SCF) and higher-order cyclic temporal cumulants (CCs) for blind modulation recognition and parameter estimation. The use of CC features is greatly enhanced by the addition of a unsupervised clustering algorithm for constellation-size estimation.
{"title":"Modulation recognition using second- and higher-order cyclostationarity","authors":"C. Spooner, A. Mody, J. Chuang, Josh Petersen","doi":"10.1109/DySPAN.2017.7920744","DOIUrl":"https://doi.org/10.1109/DySPAN.2017.7920744","url":null,"abstract":"We sketch the components of a system designed to compete in the Battle of the ModRecs Workshop at DySPAN 2017. The core ideas are the use of a flexible channelized receiver for obtaining the complex envelopes of variable-bandwidth bands-of-interest and the use of the spectral correlation function (SCF) and higher-order cyclic temporal cumulants (CCs) for blind modulation recognition and parameter estimation. The use of CC features is greatly enhanced by the addition of a unsupervised clustering algorithm for constellation-size estimation.","PeriodicalId":221877,"journal":{"name":"2017 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130421070","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 : 2017-03-06DOI: 10.1109/DySPAN.2017.7920750
K. Arumugam, I. Kadampot, Mehrdad Tahmasbi, Shaswat Shah, M. Bloch, S. Pokutta
Recent applications of machine learning to modulation recognition have demonstrated the potential of deep learning to achieve state-of-the-art performance. We propose to further extend this approach by using flexible time-space decompositions that are more in line with the actual learning task, as well as integrate side-information, such as higher order moments, directly into the training process. Our promising preliminary results suggest that there are many more benefits to be reaped from such approaches.
{"title":"Modulation recognition using side information and hybrid learning","authors":"K. Arumugam, I. Kadampot, Mehrdad Tahmasbi, Shaswat Shah, M. Bloch, S. Pokutta","doi":"10.1109/DySPAN.2017.7920750","DOIUrl":"https://doi.org/10.1109/DySPAN.2017.7920750","url":null,"abstract":"Recent applications of machine learning to modulation recognition have demonstrated the potential of deep learning to achieve state-of-the-art performance. We propose to further extend this approach by using flexible time-space decompositions that are more in line with the actual learning task, as well as integrate side-information, such as higher order moments, directly into the training process. Our promising preliminary results suggest that there are many more benefits to be reaped from such approaches.","PeriodicalId":221877,"journal":{"name":"2017 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125686515","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 : 2017-03-01DOI: 10.1109/DySPAN.2017.7920768
A. Sahoo
The Citizens Broadband Radio Service (CBRS) band has three tiers of users. The General Authorized Access (GAA) has the lowest priority and operates without a license. A Spectrum Access System (SAS) is responsible for managing spectrum among the users. The Federal Communications Commission (FCC) rules specify that GAA users be allocated resources in a fair manner, but the method to do so is left open. It is envisioned that there will be multiple SAS operators in a given region. Thus, fair partitioning of resources among SASs and fair allocation of spectrum to GAA users are important factors. In this paper, we present methods to partition resources among SASs and mechanisms that can be used by a SAS to allocate resources to a GAA user to ensure fairness.
{"title":"Fair resource allocation in the citizens broadband radio service band","authors":"A. Sahoo","doi":"10.1109/DySPAN.2017.7920768","DOIUrl":"https://doi.org/10.1109/DySPAN.2017.7920768","url":null,"abstract":"The Citizens Broadband Radio Service (CBRS) band has three tiers of users. The General Authorized Access (GAA) has the lowest priority and operates without a license. A Spectrum Access System (SAS) is responsible for managing spectrum among the users. The Federal Communications Commission (FCC) rules specify that GAA users be allocated resources in a fair manner, but the method to do so is left open. It is envisioned that there will be multiple SAS operators in a given region. Thus, fair partitioning of resources among SASs and fair allocation of spectrum to GAA users are important factors. In this paper, we present methods to partition resources among SASs and mechanisms that can be used by a SAS to allocate resources to a GAA user to ensure fairness.","PeriodicalId":221877,"journal":{"name":"2017 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128972048","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 : 2017-03-01DOI: 10.1109/DySPAN.2017.7920776
Janne Riihijärvi, Daisy Maibam, P. Mähönen
We present a framework for including model uncertainty into Monte Carlo simulations used for estimating interference risks. Through case studies based on a proof of concept implementation using SEAMCAT, we also illustrate how large impact model uncertainties can have on estimated interference probabilities. We argue that especially propagation model related uncertainties can be severe, and should definitely be considered in any quantitative study of interference risks.
{"title":"Impact of model uncertainties on quantitative evaluation of interference risks","authors":"Janne Riihijärvi, Daisy Maibam, P. Mähönen","doi":"10.1109/DySPAN.2017.7920776","DOIUrl":"https://doi.org/10.1109/DySPAN.2017.7920776","url":null,"abstract":"We present a framework for including model uncertainty into Monte Carlo simulations used for estimating interference risks. Through case studies based on a proof of concept implementation using SEAMCAT, we also illustrate how large impact model uncertainties can have on estimated interference probabilities. We argue that especially propagation model related uncertainties can be severe, and should definitely be considered in any quantitative study of interference risks.","PeriodicalId":221877,"journal":{"name":"2017 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN)","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115532000","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 : 2017-03-01DOI: 10.1109/DySPAN.2017.7920774
Ivar in 't Veen, Amjad Yousef Majid, P. Pawełczak
This poster presents a hardware/software solution, called On-The-Go Switch (OTGS), enabling a smartphone to control the connection state of a USB-attached device. Through an example, we show how OTGS can reduce the energy consumption of portable spectrum sensing platform utilizing low-cost Software Defined Radio. We show that OTGS can reduce the energy consumption by 47%, compared to a baseline, which would be difficult with a software alone, e.g. kernel modification.
这张海报展示了一种硬件/软件解决方案，称为on - go Switch (OTGS)，使智能手机能够控制usb连接设备的连接状态。通过一个实例，我们展示了OTGS如何利用低成本的软件定义无线电来降低便携式频谱传感平台的能耗。我们表明，与基线相比，OTGS可以减少47%的能耗，这对于单独的软件来说是困难的，例如内核修改。
{"title":"OTGS: Reducing energy consumption of USB-connected low-cost sensors on smartphones","authors":"Ivar in 't Veen, Amjad Yousef Majid, P. Pawełczak","doi":"10.1109/DySPAN.2017.7920774","DOIUrl":"https://doi.org/10.1109/DySPAN.2017.7920774","url":null,"abstract":"This poster presents a hardware/software solution, called On-The-Go Switch (OTGS), enabling a smartphone to control the connection state of a USB-attached device. Through an example, we show how OTGS can reduce the energy consumption of portable spectrum sensing platform utilizing low-cost Software Defined Radio. We show that OTGS can reduce the energy consumption by 47%, compared to a baseline, which would be difficult with a software alone, e.g. kernel modification.","PeriodicalId":221877,"journal":{"name":"2017 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN)","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124674810","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 : 2017-03-01DOI: 10.1109/DySPAN.2017.7920757
Martin Saint, T. Brown
This paper develops a regulatory model denoted the dynamic policy license. The dynamic policy license combines the assurances to licensees that come from holding a fixed license while maintaining regulatory flexibility. A dynamic policy license is similar to a traditional spectrum license that specifies a bandwidth, power, center frequency, location, and other parameters. However, one or more of these parameters is subject to change by the regulator over time. The allowed changes are restricted by the license to provide assurances and predictability to the licensee. The opportunities and challenges that this presents to both regulators and licensees is described. For instance, the dynamic policy license can be a regulatory tool for more aggressive spectrum sharing.
{"title":"The dynamic policy license","authors":"Martin Saint, T. Brown","doi":"10.1109/DySPAN.2017.7920757","DOIUrl":"https://doi.org/10.1109/DySPAN.2017.7920757","url":null,"abstract":"This paper develops a regulatory model denoted the dynamic policy license. The dynamic policy license combines the assurances to licensees that come from holding a fixed license while maintaining regulatory flexibility. A dynamic policy license is similar to a traditional spectrum license that specifies a bandwidth, power, center frequency, location, and other parameters. However, one or more of these parameters is subject to change by the regulator over time. The allowed changes are restricted by the license to provide assurances and predictability to the licensee. The opportunities and challenges that this presents to both regulators and licensees is described. For instance, the dynamic policy license can be a regulatory tool for more aggressive spectrum sharing.","PeriodicalId":221877,"journal":{"name":"2017 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131006169","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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