Pub Date : 2002-08-07DOI: 10.1109/VTC.2002.1002664
Kai Liu, Jiandong Li, Pengyu Huang, A. Fukuda
This paper presents a new multiple access control (MAC) protocol called adaptive acquisition multiple access with common-transmission channel assignment (AAMA-CT) and its improved one (AAMA-ICT) for wireless multihop mobile ad hoc networks. In the protocol, every node adaptively chooses a usable channel as its transmission channel in advance in multihop mobile environment and takes advantage of request-to-send (RTS) packet transmitted on a common channel to evoke its recipient to complete their communication process on their transmission channels without packet collisions. With this protocol, resource reservation is flexibly and effectively made on multiple channels by half-duplex radios without any help of powerful central controllers and wired backbone networks in an asynchronous fashion. The protocol can solve hidden and exposed terminal problems perfectly as is validated through analysis and simulation results.
针对无线多跳移动自组网，提出了一种新的多址控制协议AAMA-CT (adaptive acquisition multiple access with common-transmission channel assignment)及其改进协议AAMA-ICT。该协议在多跳移动环境下，每个节点提前自适应地选择一个可用的信道作为自己的传输信道，并利用在公共信道上传输的RTS (request-to-send)分组，在不发生分组冲突的情况下，唤醒接收方在各自的传输信道上完成通信过程。使用该协议，可以在不需要任何强大的中央控制器和有线骨干网的帮助下，以异步方式通过半双工无线电在多个信道上灵活有效地进行资源预留。分析和仿真结果验证了该协议能够很好地解决终端隐藏和暴露问题。
{"title":"Adaptive acquisition multiple access protocol in wireless multihop mobile ad hoc networks","authors":"Kai Liu, Jiandong Li, Pengyu Huang, A. Fukuda","doi":"10.1109/VTC.2002.1002664","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002664","url":null,"abstract":"This paper presents a new multiple access control (MAC) protocol called adaptive acquisition multiple access with common-transmission channel assignment (AAMA-CT) and its improved one (AAMA-ICT) for wireless multihop mobile ad hoc networks. In the protocol, every node adaptively chooses a usable channel as its transmission channel in advance in multihop mobile environment and takes advantage of request-to-send (RTS) packet transmitted on a common channel to evoke its recipient to complete their communication process on their transmission channels without packet collisions. With this protocol, resource reservation is flexibly and effectively made on multiple channels by half-duplex radios without any help of powerful central controllers and wired backbone networks in an asynchronous fashion. The protocol can solve hidden and exposed terminal problems perfectly as is validated through analysis and simulation results.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133549709","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 : 2002-08-07DOI: 10.1109/VTC.2002.1002875
R. Narasimha, S. Dianat
In this paper we propose a new blind adaptive decision-feedback multiuser detector (BADFP) for synchronous direct-sequence code-division multiple-access (DS-CDMA) systems. The BADFP algorithm is a stochastic adaptive gradient type algorithm that incorporates power estimation of the user of interest to enhance the performance of the detector. It is assumed that full power control is in place and all the users are equally powered. The proposed algorithm requires the knowledge of the signature sequence of the desired user. The simulation results show that the performance of the BADFP algorithm is comparable with the ideal blind linear minimum output energy (MOE) detector.
{"title":"Blind adaptive decision feedback multiuser detector for DS-CDMA with power estimation","authors":"R. Narasimha, S. Dianat","doi":"10.1109/VTC.2002.1002875","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002875","url":null,"abstract":"In this paper we propose a new blind adaptive decision-feedback multiuser detector (BADFP) for synchronous direct-sequence code-division multiple-access (DS-CDMA) systems. The BADFP algorithm is a stochastic adaptive gradient type algorithm that incorporates power estimation of the user of interest to enhance the performance of the detector. It is assumed that full power control is in place and all the users are equally powered. The proposed algorithm requires the knowledge of the signature sequence of the desired user. The simulation results show that the performance of the BADFP algorithm is comparable with the ideal blind linear minimum output energy (MOE) detector.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134474032","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 : 2002-08-07DOI: 10.1109/VTC.2002.1002561
M. Ebrahimi, M. Nasiri-Kenari
We consider the multiuser capacity of a multicarrier frequency-hopping (MC-FH) CDMA system as first introduced by Lance and Kaleh (1997). We propose to use a practical low-rate convolutional error correcting code in this system which does not require any extra bandwidth further than needed by the frequency-hopping spread-spectrum modulation. We provide a multiuser performance analysis of the system for both uncoded and coded schemes in AWGN and fading channels based on a Gaussian distribution assumption for the multiuser interference term. We also derive the exact bit error rate (BER) of the system in an AWGN channel. Our numerical results first indicate that the coded scheme significantly outperforms the uncoded scheme in both AWGN and fading channels. Moreover, it shows that the Gaussian analysis in some cases does not predict accurately the number of users supported by the system.
{"title":"Performance analysis of multicarrier frequency-hopping (MC-FH) code division multiple-access systems: uncoded and coded schemes","authors":"M. Ebrahimi, M. Nasiri-Kenari","doi":"10.1109/VTC.2002.1002561","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002561","url":null,"abstract":"We consider the multiuser capacity of a multicarrier frequency-hopping (MC-FH) CDMA system as first introduced by Lance and Kaleh (1997). We propose to use a practical low-rate convolutional error correcting code in this system which does not require any extra bandwidth further than needed by the frequency-hopping spread-spectrum modulation. We provide a multiuser performance analysis of the system for both uncoded and coded schemes in AWGN and fading channels based on a Gaussian distribution assumption for the multiuser interference term. We also derive the exact bit error rate (BER) of the system in an AWGN channel. Our numerical results first indicate that the coded scheme significantly outperforms the uncoded scheme in both AWGN and fading channels. Moreover, it shows that the Gaussian analysis in some cases does not predict accurately the number of users supported by the system.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130310619","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 : 2002-08-07DOI: 10.1109/VTC.2002.1002712
A. Wittneben, M. Kuhn
Future wireless communication systems are characterized by heterogeneity in terms of node capabilities, link level requirements, propagation environments, cell designs and subnet structures. High carrier frequencies and large system bandwidth will make extreme diversity factors feasible. This imposes new requirements on space-time codes. We present a new concatenated linear space-time block coding scheme, which meets these requirements. The code consists of a linear time variant inner code and a linear time invariant outer code. We intentionally decouple the designs of each constituent code in order to achieve the required adaptivity. The inner code is optimized with respect to the variation of the instantaneous channel capacity over the block length of the outer code. Efficient inner coding matrices are given for pure TX diversity and joint spatial subchanneling and TX diversity. The linear outer code is optimized for diversity performance. We describe an efficient approach for the optimization of an unitary coding matrix for any given block length. Simulation results for different system parameters are presented. It is concluded that the proposed concatenated linear high rate space-time block coding scheme is a promising candidate for heterogeneous future mobile communication systems.
{"title":"A new concatenated linear high rate space-time block code","authors":"A. Wittneben, M. Kuhn","doi":"10.1109/VTC.2002.1002712","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002712","url":null,"abstract":"Future wireless communication systems are characterized by heterogeneity in terms of node capabilities, link level requirements, propagation environments, cell designs and subnet structures. High carrier frequencies and large system bandwidth will make extreme diversity factors feasible. This imposes new requirements on space-time codes. We present a new concatenated linear space-time block coding scheme, which meets these requirements. The code consists of a linear time variant inner code and a linear time invariant outer code. We intentionally decouple the designs of each constituent code in order to achieve the required adaptivity. The inner code is optimized with respect to the variation of the instantaneous channel capacity over the block length of the outer code. Efficient inner coding matrices are given for pure TX diversity and joint spatial subchanneling and TX diversity. The linear outer code is optimized for diversity performance. We describe an efficient approach for the optimization of an unitary coding matrix for any given block length. Simulation results for different system parameters are presented. It is concluded that the proposed concatenated linear high rate space-time block coding scheme is a promising candidate for heterogeneous future mobile communication systems.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122904608","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 : 2002-08-07DOI: 10.1109/VTC.2002.1002879
X. Qi, Mohamed-Slim Alouini, Young-Chai Ko
Starting with a new expression for the probability density function of the signal-to-noise ratio at the output of dual-diversity equal-gain combining (EGC) over not identically distributed Rayleigh channels, we provide closed-form expressions for the outage probability as well as average bit and symbol error rate of binary and M-ary phase-shift keying signals. Numerical examples indicate that EGC maintains a good diversity gain as long as the degree of unbalance is not very low but suffers a sharp and significant degradation when the degree of unbalance approaches zero.
{"title":"Closed-form analysis of dual-diversity equal-gain combiners over Rayleigh fading channels","authors":"X. Qi, Mohamed-Slim Alouini, Young-Chai Ko","doi":"10.1109/VTC.2002.1002879","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002879","url":null,"abstract":"Starting with a new expression for the probability density function of the signal-to-noise ratio at the output of dual-diversity equal-gain combining (EGC) over not identically distributed Rayleigh channels, we provide closed-form expressions for the outage probability as well as average bit and symbol error rate of binary and M-ary phase-shift keying signals. Numerical examples indicate that EGC maintains a good diversity gain as long as the degree of unbalance is not very low but suffers a sharp and significant degradation when the degree of unbalance approaches zero.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123103006","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 : 2002-08-07DOI: 10.1109/VTC.2002.1002908
B. Yeap, T. Liew, L. Hanzo
A reduced complexity turbo equalizer, TEQ-IQ, which uses the in-phase/quadrature-phase cancellation technique developed for single-transmitter and single-receiver systems, is proposed for space-time trellis coded (STTC) systems. The TEQ-IQ scheme is capable of approximating the performance of the conventional turbo equalizer (TEQ-CT), while achieving complexity reduction factors of 1.4 and 468.2 for a 4PSK 32-state STTC system communicating over two-path and five-path symbol-spaced and equal tap weight Rayleigh fading channels, respectively.
{"title":"Reduced complexity turbo equalization for space-time trellis coded systems","authors":"B. Yeap, T. Liew, L. Hanzo","doi":"10.1109/VTC.2002.1002908","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002908","url":null,"abstract":"A reduced complexity turbo equalizer, TEQ-IQ, which uses the in-phase/quadrature-phase cancellation technique developed for single-transmitter and single-receiver systems, is proposed for space-time trellis coded (STTC) systems. The TEQ-IQ scheme is capable of approximating the performance of the conventional turbo equalizer (TEQ-CT), while achieving complexity reduction factors of 1.4 and 468.2 for a 4PSK 32-state STTC system communicating over two-path and five-path symbol-spaced and equal tap weight Rayleigh fading channels, respectively.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134255523","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 : 2002-08-07DOI: 10.1109/VTC.2002.1002803
K. Nakano, M. Sengoku, S. Shinoda
This paper considers the call dropping probability in cellular systems with multihop wireless networking, and evaluates the relation between the call dropping probability and mobility patterns of the nodes. Also, this paper considers the difference between a cellular network with multihop networking and a multihop network without base stations. To compare these networks, the call dropping probability and the mean lifetime of a path are considered.
{"title":"Effect of mobility on connectivity of mobile multihop wireless networks","authors":"K. Nakano, M. Sengoku, S. Shinoda","doi":"10.1109/VTC.2002.1002803","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002803","url":null,"abstract":"This paper considers the call dropping probability in cellular systems with multihop wireless networking, and evaluates the relation between the call dropping probability and mobility patterns of the nodes. Also, this paper considers the difference between a cellular network with multihop networking and a multihop network without base stations. To compare these networks, the call dropping probability and the mean lifetime of a path are considered.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132543526","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 : 2002-08-07DOI: 10.1109/VTC.2002.1002698
S. Sibecas, C. Corral, S. Emami, G. Stratis
The 802.11a standard has been considered and applied to DSRC (dedicated short-range communication) in the 5.9 GHz band. Among the parameters of the DSRC are support for data transfers during high-mobility applications. Given that the 802.11a standard was designed for relatively low speed (3 MPH) wireless LAN applications, it is necessary to analyze the suitability of the standard in outdoor high-speed mobility applications. We present an analysis of the error rate of 802.11a in high-speed mobile applications. It is shown that 802.11a/RA communication exhibits high packet error rates and consequently lower channel capacity. An example is submitted and discussed.
{"title":"On the suitability of 802.11a/RA for high-mobility DSRC","authors":"S. Sibecas, C. Corral, S. Emami, G. Stratis","doi":"10.1109/VTC.2002.1002698","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002698","url":null,"abstract":"The 802.11a standard has been considered and applied to DSRC (dedicated short-range communication) in the 5.9 GHz band. Among the parameters of the DSRC are support for data transfers during high-mobility applications. Given that the 802.11a standard was designed for relatively low speed (3 MPH) wireless LAN applications, it is necessary to analyze the suitability of the standard in outdoor high-speed mobility applications. We present an analysis of the error rate of 802.11a in high-speed mobile applications. It is shown that 802.11a/RA communication exhibits high packet error rates and consequently lower channel capacity. An example is submitted and discussed.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"63 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134361077","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 : 2002-08-07DOI: 10.1109/VTC.2002.1002820
J. Maurer, T. Fügen, W. Wiesbeck
The inter-vehicle transmission channel is characterised based on narrow-band measurements at 5.2 GHz. The measurement setup consists of a transmitter and a receiver, which are installed in two different vehicles. While measuring the transmission channel, both vehicles are manoeuvred in realistic road traffic scenarios. Measurements are obtained for four different classes of environments: urban, suburban (village), motorway and highway. Statistical functions, such as the cumulative distribution function (CDF) of the received signal, the average Doppler power density spectrum and the level crossing rate (LCR), are derived for each class. The measured results are compared to analytical functions, such as the Rice, the Rayleigh, the Gauss or the Nakagami distribution. The least squares and the conjugate gradient method are used to fit the parameters of the analytical functions to the measurement data.
{"title":"Narrow-band measurement and analysis of the inter-vehicle transmission channel at 5.2 GHz","authors":"J. Maurer, T. Fügen, W. Wiesbeck","doi":"10.1109/VTC.2002.1002820","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002820","url":null,"abstract":"The inter-vehicle transmission channel is characterised based on narrow-band measurements at 5.2 GHz. The measurement setup consists of a transmitter and a receiver, which are installed in two different vehicles. While measuring the transmission channel, both vehicles are manoeuvred in realistic road traffic scenarios. Measurements are obtained for four different classes of environments: urban, suburban (village), motorway and highway. Statistical functions, such as the cumulative distribution function (CDF) of the received signal, the average Doppler power density spectrum and the level crossing rate (LCR), are derived for each class. The measured results are compared to analytical functions, such as the Rice, the Rayleigh, the Gauss or the Nakagami distribution. The least squares and the conjugate gradient method are used to fit the parameters of the analytical functions to the measurement data.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133277329","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 : 2002-08-07DOI: 10.1109/VTC.2002.1002719
H. Jwa, H. Oh, M. Kyeong
In chip-level beamforming using known pilot symbols as reference signal (PSCLB, pilot symbol assisted chip-level beamforming), the chip-level beamformer cannot separate the signals corresponding to the transmitted pilot symbols passed through the wireless channel from the received signal, so that its performance may be degraded in the WCDMA antenna array system. This paper presents two appropriate chip-level reference signals for chip-level beamforming employing decision directed data and assisting known pilot symbols (DDCLB, decision-directed chip-level beamforming) in a WCDMA antenna array system. The simulation results show that the performance of DDCLB is improved significantly compared to PSCLB in the mobile channel model.
{"title":"Decision-directed chip-level beamforming in WCDMA antenna array system","authors":"H. Jwa, H. Oh, M. Kyeong","doi":"10.1109/VTC.2002.1002719","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002719","url":null,"abstract":"In chip-level beamforming using known pilot symbols as reference signal (PSCLB, pilot symbol assisted chip-level beamforming), the chip-level beamformer cannot separate the signals corresponding to the transmitted pilot symbols passed through the wireless channel from the received signal, so that its performance may be degraded in the WCDMA antenna array system. This paper presents two appropriate chip-level reference signals for chip-level beamforming employing decision directed data and assisting known pilot symbols (DDCLB, decision-directed chip-level beamforming) in a WCDMA antenna array system. The simulation results show that the performance of DDCLB is improved significantly compared to PSCLB in the mobile channel model.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132762240","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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