Pub Date : 2011-06-01DOI: 10.4108/ICST.CROWNCOM.2011.246247
Z. Khan, Janne J. Lehtomäki, M. Mustonen, M. Matinmikko
When autonomous cognitive radios (CRs) have to search multiple potential channels for spectrum opportunities, they face competition from one another to access the channel. The end result of this competition is reduced CR throughput due to collisions among CRs that transmit in the same channel. In this context, the channel sensing order, i.e., the order in which CRs competing for the channels visit those channels, will affect their probability of successful access. This paper presents an investigation into the sensing order dispersion problem, where two or more autonomous CRs attempt to avoid one another by selecting those sensing orders that reduce the likelihood of collisions among one another. We present adaptive strategies that enable the CRs to achieve sensing order dispersion. We evaluate the performance of the presented adaptive strategies in terms of expected time for the autonomous CRs to reach collision-free sensing orders and also in terms of average number of successful transmissions in the network.
{"title":"Sensing order dispersion for autonomous cognitive radios","authors":"Z. Khan, Janne J. Lehtomäki, M. Mustonen, M. Matinmikko","doi":"10.4108/ICST.CROWNCOM.2011.246247","DOIUrl":"https://doi.org/10.4108/ICST.CROWNCOM.2011.246247","url":null,"abstract":"When autonomous cognitive radios (CRs) have to search multiple potential channels for spectrum opportunities, they face competition from one another to access the channel. The end result of this competition is reduced CR throughput due to collisions among CRs that transmit in the same channel. In this context, the channel sensing order, i.e., the order in which CRs competing for the channels visit those channels, will affect their probability of successful access. This paper presents an investigation into the sensing order dispersion problem, where two or more autonomous CRs attempt to avoid one another by selecting those sensing orders that reduce the likelihood of collisions among one another. We present adaptive strategies that enable the CRs to achieve sensing order dispersion. We evaluate the performance of the presented adaptive strategies in terms of expected time for the autonomous CRs to reach collision-free sensing orders and also in terms of average number of successful transmissions in the network.","PeriodicalId":249175,"journal":{"name":"2011 6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116738399","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 : 2011-06-01DOI: 10.4108/ICST.CROWNCOM.2011.245843
J. Vartiainen, Janne J. Lehtomäki, Timo Bräysy, K. Umebayashi
Public safety communications (PSC) are invaluable in safety critical scenarios such as floods or earthquakes when commercial communication systems fall down. Cognitive radio (CR) approach that is independent of other communication systems provides flexibility and certainty. One of the key issues is to reliably find unused radio channels also in the situations when there is no a priori information about possible other users. In this paper, we propose using the two-dimensional localization algorithm based on double-thresholding with adjacent cluster combining (2-D LAD ACC) method for detecting free channels. It is low-complex, blind and able to operate in any frequency area. This paper applies the 2-D LAD ACC method for real-world channel measurement data for the first time. The indoor measurements at WLAN bands verify that the 2-D LAD ACC method is able to operate in the real-life situation.
{"title":"Spectrum sensing in public safety applications: The 2-D LAD ACC method","authors":"J. Vartiainen, Janne J. Lehtomäki, Timo Bräysy, K. Umebayashi","doi":"10.4108/ICST.CROWNCOM.2011.245843","DOIUrl":"https://doi.org/10.4108/ICST.CROWNCOM.2011.245843","url":null,"abstract":"Public safety communications (PSC) are invaluable in safety critical scenarios such as floods or earthquakes when commercial communication systems fall down. Cognitive radio (CR) approach that is independent of other communication systems provides flexibility and certainty. One of the key issues is to reliably find unused radio channels also in the situations when there is no a priori information about possible other users. In this paper, we propose using the two-dimensional localization algorithm based on double-thresholding with adjacent cluster combining (2-D LAD ACC) method for detecting free channels. It is low-complex, blind and able to operate in any frequency area. This paper applies the 2-D LAD ACC method for real-world channel measurement data for the first time. The indoor measurements at WLAN bands verify that the 2-D LAD ACC method is able to operate in the real-life situation.","PeriodicalId":249175,"journal":{"name":"2011 6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128590242","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 : 2011-06-01DOI: 10.4108/ICST.CROWNCOM.2011.245822
H. Fujii, S. Miura, H. Kayama
A theoretical analysis of achievable capacity by a cognitive radio systems is discussed, when the cognitive radio system (CRS) uses spectrum allocated to a macro cellular system. As for the spectrum sharing mechanisms, we consider two methods based on listen-before-talk and adaptive transmit power control principles. Moreover, outdoor and indoor installations of CRS stations are investigated. Numerical results reveal capacities achieved by CRS base stations installed within the coverage area of the macro cell system.
{"title":"Achievable capacity of cognitive radio systems coexisting with a macro cellular system","authors":"H. Fujii, S. Miura, H. Kayama","doi":"10.4108/ICST.CROWNCOM.2011.245822","DOIUrl":"https://doi.org/10.4108/ICST.CROWNCOM.2011.245822","url":null,"abstract":"A theoretical analysis of achievable capacity by a cognitive radio systems is discussed, when the cognitive radio system (CRS) uses spectrum allocated to a macro cellular system. As for the spectrum sharing mechanisms, we consider two methods based on listen-before-talk and adaptive transmit power control principles. Moreover, outdoor and indoor installations of CRS stations are investigated. Numerical results reveal capacities achieved by CRS base stations installed within the coverage area of the macro cell system.","PeriodicalId":249175,"journal":{"name":"2011 6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132745137","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 : 2011-06-01DOI: 10.4108/ICST.CROWNCOM.2011.246253
Wenbin Guo, Xing Wang, Yang Lu, Wenbo Wang
The structure of block sparsity in multi-band signals is prevalent. Performance of recovery algorithms that taking advantage of the block sparsity structure is promising in the compressed sensing framework. In this paper, we propose a binary tree based recovery algorithm for block-sparse signals, where we exploit the fact that each block may have zero and nonzero elements both. The proposed algorithm improves the current algorithms through iteratively separating the recovered blocks of signals into two smaller blocks. Therefore, greedy searching based algorithm is possible to obtain more accurate basis for signal recovery. Simulations are performed and the results show the improvements over current block-based recovery algorithms.
{"title":"A tree based recovery algorithm for block sparse signals","authors":"Wenbin Guo, Xing Wang, Yang Lu, Wenbo Wang","doi":"10.4108/ICST.CROWNCOM.2011.246253","DOIUrl":"https://doi.org/10.4108/ICST.CROWNCOM.2011.246253","url":null,"abstract":"The structure of block sparsity in multi-band signals is prevalent. Performance of recovery algorithms that taking advantage of the block sparsity structure is promising in the compressed sensing framework. In this paper, we propose a binary tree based recovery algorithm for block-sparse signals, where we exploit the fact that each block may have zero and nonzero elements both. The proposed algorithm improves the current algorithms through iteratively separating the recovered blocks of signals into two smaller blocks. Therefore, greedy searching based algorithm is possible to obtain more accurate basis for signal recovery. Simulations are performed and the results show the improvements over current block-based recovery algorithms.","PeriodicalId":249175,"journal":{"name":"2011 6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133867136","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 : 2011-06-01DOI: 10.4108/ICST.CROWNCOM.2011.245830
Jianfei Wang, Jinzhao Su, Wei Wu
We advocate an online spectrum allocation system for cognitive cellular network supporting scalable demands. Our system's demands processing model is online model, which means that allocation result is returned immediately. To solve the tough issues of online spectrum allocation, we try to balance the spectrum utilization and future coming demands. A state machine is introduced to allocate spectrum efficiently, and at different state system have different procedures to provide service to customers. To make good use of scalable property of demand and to increase fairness among customers, the concept of satisfaction degree is introduced. We also analyze our system's state and its transition theoretically and give the derivation of every parameter of system and the method to calculate them. Enough work is done to evaluate the system with real data evaluation and results show that the system is efficient and robust under different cases in which the customers' arrival rate and service time are varied.
{"title":"Online spectrum allocation for cognitive cellular network supporting scalable demands","authors":"Jianfei Wang, Jinzhao Su, Wei Wu","doi":"10.4108/ICST.CROWNCOM.2011.245830","DOIUrl":"https://doi.org/10.4108/ICST.CROWNCOM.2011.245830","url":null,"abstract":"We advocate an online spectrum allocation system for cognitive cellular network supporting scalable demands. Our system's demands processing model is online model, which means that allocation result is returned immediately. To solve the tough issues of online spectrum allocation, we try to balance the spectrum utilization and future coming demands. A state machine is introduced to allocate spectrum efficiently, and at different state system have different procedures to provide service to customers. To make good use of scalable property of demand and to increase fairness among customers, the concept of satisfaction degree is introduced. We also analyze our system's state and its transition theoretically and give the derivation of every parameter of system and the method to calculate them. Enough work is done to evaluate the system with real data evaluation and results show that the system is efficient and robust under different cases in which the customers' arrival rate and service time are varied.","PeriodicalId":249175,"journal":{"name":"2011 6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126316358","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 : 2011-06-01DOI: 10.4108/ICST.CROWNCOM.2011.245882
X. Tan, Liang Li, Wei Guo
One of the key issues in cognitive transmission is for secondary users to dynamically acquire spare spectrum from the primary user and then select appropriate transmission schemes. The existing spectrum sharing scheme adopts a deterministic Cournot game to formulate this problem, of which the solution is Nash equilibrium. This formulation implicitly assumes that each secondary user is willing to fully exchange transmission parameters with all other users and hence knows the complete information of all others. However, this assumption may not be true in general. To remedy this, the present paper considers a more realistic assumption of incomplete information, i.e., each secondary user may choose to conceal its private information for achieving higher transmission benefit. Following this assumption, we adopt a probabilistic Cournot game to propose an opportunistic transmission scheme to maximize the transmission benefit of all secondary users. Bayesian equilibrium is considered as the solution of this game. Moreover, we rigorously prove that a secondary user can improve its expected transmission benefit by actively hiding its private transmission parameters and increasing the variance of its allocated spectrum.
{"title":"A game-theoretic approach for opportunistic transmission scheme in cognitive radio networks with incomplete information","authors":"X. Tan, Liang Li, Wei Guo","doi":"10.4108/ICST.CROWNCOM.2011.245882","DOIUrl":"https://doi.org/10.4108/ICST.CROWNCOM.2011.245882","url":null,"abstract":"One of the key issues in cognitive transmission is for secondary users to dynamically acquire spare spectrum from the primary user and then select appropriate transmission schemes. The existing spectrum sharing scheme adopts a deterministic Cournot game to formulate this problem, of which the solution is Nash equilibrium. This formulation implicitly assumes that each secondary user is willing to fully exchange transmission parameters with all other users and hence knows the complete information of all others. However, this assumption may not be true in general. To remedy this, the present paper considers a more realistic assumption of incomplete information, i.e., each secondary user may choose to conceal its private information for achieving higher transmission benefit. Following this assumption, we adopt a probabilistic Cournot game to propose an opportunistic transmission scheme to maximize the transmission benefit of all secondary users. Bayesian equilibrium is considered as the solution of this game. Moreover, we rigorously prove that a secondary user can improve its expected transmission benefit by actively hiding its private transmission parameters and increasing the variance of its allocated spectrum.","PeriodicalId":249175,"journal":{"name":"2011 6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131115887","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 : 2011-06-01DOI: 10.4108/ICST.CROWNCOM.2011.246154
I. Mustika, Koji Yamamoto, H. Murata, S. Yoshida
In the present paper, a self-organization scheme for joint base station selection and resource block allocation in an OFDMA cellular network is proposed. The network consists of overlaying macrocell and indoor picocells with open access configuration. Inspired by the cognitive radio technology, each mobile user in heterogeneous network selects the most appropriate base station and allocates resource blocks in a decentralized fashion in order to manage the cross- and co-tier interference, and improve the throughput performance. The problem is formulated as a potential game, which is demonstrated to converge to a Nash equilibrium when distributed sequential play based on the best response dynamics is adopted. The simulation results show that the proposed self-organization scheme improves the uplink system capacity of the heterogeneous networks with a slight loss of the picocell performance.
{"title":"Potential game approach for self-organization scheme in open access heterogeneous networks","authors":"I. Mustika, Koji Yamamoto, H. Murata, S. Yoshida","doi":"10.4108/ICST.CROWNCOM.2011.246154","DOIUrl":"https://doi.org/10.4108/ICST.CROWNCOM.2011.246154","url":null,"abstract":"In the present paper, a self-organization scheme for joint base station selection and resource block allocation in an OFDMA cellular network is proposed. The network consists of overlaying macrocell and indoor picocells with open access configuration. Inspired by the cognitive radio technology, each mobile user in heterogeneous network selects the most appropriate base station and allocates resource blocks in a decentralized fashion in order to manage the cross- and co-tier interference, and improve the throughput performance. The problem is formulated as a potential game, which is demonstrated to converge to a Nash equilibrium when distributed sequential play based on the best response dynamics is adopted. The simulation results show that the proposed self-organization scheme improves the uplink system capacity of the heterogeneous networks with a slight loss of the picocell performance.","PeriodicalId":249175,"journal":{"name":"2011 6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128080258","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 : 2011-06-01DOI: 10.4108/ICST.CROWNCOM.2011.245917
Seungmo Kim, Tahjoon Park, Wan Choi, Youngnam Han
We analyze the capacity of cognitive ad-hoc networks under the effects of sensing errors: false alarm and missed detection. We present an ad-hoc network model overlaid on a primary system from which a cognitive node exploits spectrum holes for retransmissions. We derive per-link capacity, the indicator of the network's capacity, by considering statistics of the primary users' (PUs) channel occupancy and sensing errors. Our analysis shows that the capacity scaling law is kept unchanged, O(1/√log n) by the number of nodes n, even after sensing errors are introduced. It also shows how the capacity depends on the PUs' channel occupancy and sensing errors.
{"title":"The capacity of cognitive ad-hoc networks with carrier sensing errors","authors":"Seungmo Kim, Tahjoon Park, Wan Choi, Youngnam Han","doi":"10.4108/ICST.CROWNCOM.2011.245917","DOIUrl":"https://doi.org/10.4108/ICST.CROWNCOM.2011.245917","url":null,"abstract":"We analyze the capacity of cognitive ad-hoc networks under the effects of sensing errors: false alarm and missed detection. We present an ad-hoc network model overlaid on a primary system from which a cognitive node exploits spectrum holes for retransmissions. We derive per-link capacity, the indicator of the network's capacity, by considering statistics of the primary users' (PUs) channel occupancy and sensing errors. Our analysis shows that the capacity scaling law is kept unchanged, O(1/√log n) by the number of nodes n, even after sensing errors are introduced. It also shows how the capacity depends on the PUs' channel occupancy and sensing errors.","PeriodicalId":249175,"journal":{"name":"2011 6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114234835","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 : 2011-06-01DOI: 10.4108/ICST.CROWNCOM.2011.245883
Guillaume Fumat, P. Chargé, A. Zoubir, D. Fournier-Prunaret
Transform Domain Communication System (TDCS) is a Cognitive Radio technology that has been thoroughly studied by the Air Force Institute of Technology because of its resiliency against jammers or interferences while being noise-like. However TDCS' huge disadvantage is its low spectral efficiency. In this article, we propose the use of a dense multidimensional modulation to counteract this property. We develop the theoretical Bit Error Rate (BER) performance and show that the theory matches well the simulation. We point out that this modulation can compete with QPSK systems in terms of spectral efficiency while keeping TDCS' intrinsic assets.
{"title":"Enhancing spectral efficiency of Transform Domain Communication Systems by using a multidimensional modulation","authors":"Guillaume Fumat, P. Chargé, A. Zoubir, D. Fournier-Prunaret","doi":"10.4108/ICST.CROWNCOM.2011.245883","DOIUrl":"https://doi.org/10.4108/ICST.CROWNCOM.2011.245883","url":null,"abstract":"Transform Domain Communication System (TDCS) is a Cognitive Radio technology that has been thoroughly studied by the Air Force Institute of Technology because of its resiliency against jammers or interferences while being noise-like. However TDCS' huge disadvantage is its low spectral efficiency. In this article, we propose the use of a dense multidimensional modulation to counteract this property. We develop the theoretical Bit Error Rate (BER) performance and show that the theory matches well the simulation. We point out that this modulation can compete with QPSK systems in terms of spectral efficiency while keeping TDCS' intrinsic assets.","PeriodicalId":249175,"journal":{"name":"2011 6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127924842","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 : 2011-06-01DOI: 10.4108/ICST.CROWNCOM.2011.246140
H. Harada, Y. Alemseged, O. Holland
This article presents the latest status and achievements of the IEEE Communication Society (ComSoc) Standards for Dynamic Spectrum Access Networks (DYSPAN), formerly IEEE Standards Coordinating Committee 41, that develops standards in the areas of dynamic spectrum access, cognitive radio, interference management, coordination of wireless systems, advanced spectrum management, and policy languages for next generation radio systems under the sponsorship of the IEEE communications society. The article also envisions future directions for the DYSPAN Committee. This paper represents the personal opinion of the authors, not the official opinion of the IEEE ComSoc DYSPAN standards committee.
{"title":"IEEE Dynamic Spectrum Access Networks (DYSPAN) standards committee","authors":"H. Harada, Y. Alemseged, O. Holland","doi":"10.4108/ICST.CROWNCOM.2011.246140","DOIUrl":"https://doi.org/10.4108/ICST.CROWNCOM.2011.246140","url":null,"abstract":"This article presents the latest status and achievements of the IEEE Communication Society (ComSoc) Standards for Dynamic Spectrum Access Networks (DYSPAN), formerly IEEE Standards Coordinating Committee 41, that develops standards in the areas of dynamic spectrum access, cognitive radio, interference management, coordination of wireless systems, advanced spectrum management, and policy languages for next generation radio systems under the sponsorship of the IEEE communications society. The article also envisions future directions for the DYSPAN Committee. This paper represents the personal opinion of the authors, not the official opinion of the IEEE ComSoc DYSPAN standards committee.","PeriodicalId":249175,"journal":{"name":"2011 6th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM)","volume":"81 2-3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132534469","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：