Pub Date : 2004-12-01DOI: 10.1109/VETECF.2004.1400013
Myoung-Won Lee, Cheol Mun, Jin-Kyu Han, J. Yook, Han-kyu Park
In this paper, the performance of a multiuser diversity system paired with a multi-element transmit antenna system is analyzed under the assumption of independent Rayleigh fading. A measure of system level performance is an achievable spectral efficiency as a function of the number of users and antennas. Spectral efficiency is obtained from the instantaneous signal-to-noise ratio (SNR) distribution combined by both transmit diversity at each link and multiuser diversity at system level when the base station transmitter adapts to channel variations using a constant power variable rate strategy. Numerical results show that closed-loop antenna techniques provide an additional gain with multiuser diversity systems due to array gain, even though space diversity gain reduces multiuser diversity gain. On the other hand, the space-time block coding (STBC) that provides full order space diversity gain only has a destructive impact on multiuser diversity.
{"title":"Analysis on the impact of multi-element transmit antenna system on multiuser diversity [mobile wireless systems]","authors":"Myoung-Won Lee, Cheol Mun, Jin-Kyu Han, J. Yook, Han-kyu Park","doi":"10.1109/VETECF.2004.1400013","DOIUrl":"https://doi.org/10.1109/VETECF.2004.1400013","url":null,"abstract":"In this paper, the performance of a multiuser diversity system paired with a multi-element transmit antenna system is analyzed under the assumption of independent Rayleigh fading. A measure of system level performance is an achievable spectral efficiency as a function of the number of users and antennas. Spectral efficiency is obtained from the instantaneous signal-to-noise ratio (SNR) distribution combined by both transmit diversity at each link and multiuser diversity at system level when the base station transmitter adapts to channel variations using a constant power variable rate strategy. Numerical results show that closed-loop antenna techniques provide an additional gain with multiuser diversity systems due to array gain, even though space diversity gain reduces multiuser diversity gain. On the other hand, the space-time block coding (STBC) that provides full order space diversity gain only has a destructive impact on multiuser diversity.","PeriodicalId":337062,"journal":{"name":"IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115757529","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}
The 3G mobile standard offers an unprecedented high speed digital service that can carry multimedia traffic such as video streaming. The distributed system buffers in the conventional client-server architecture absorb the fluctuations of channel conditions such as bit rate variations, delays and jitters. To enable easy control of the 3G system, the MPEG committee is developing scalable video coding technology that provides flexibility for transmission over wireless networks. This paper address issues in controlling these buffers that can impact and benefit the end-to-end system performance using the novel scalable video technology. Specifically, we explore the effects of diverse channel characteristics on the buffers performance tolerance, and its impact on the quality of service. A novel model-based adaptive media playout (AMP) buffer control is proposed to mitigate the risks of buffer outage.
{"title":"On the buffer dynamics of scalable video streaming over wireless network","authors":"Hsiao-Chiang Chuang, Ching-Yao Huang, Tihao Chiang","doi":"10.1109/VETECF.2004.1400523","DOIUrl":"https://doi.org/10.1109/VETECF.2004.1400523","url":null,"abstract":"The 3G mobile standard offers an unprecedented high speed digital service that can carry multimedia traffic such as video streaming. The distributed system buffers in the conventional client-server architecture absorb the fluctuations of channel conditions such as bit rate variations, delays and jitters. To enable easy control of the 3G system, the MPEG committee is developing scalable video coding technology that provides flexibility for transmission over wireless networks. This paper address issues in controlling these buffers that can impact and benefit the end-to-end system performance using the novel scalable video technology. Specifically, we explore the effects of diverse channel characteristics on the buffers performance tolerance, and its impact on the quality of service. A novel model-based adaptive media playout (AMP) buffer control is proposed to mitigate the risks of buffer outage.","PeriodicalId":337062,"journal":{"name":"IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134146627","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 : 2004-12-01DOI: 10.1109/VETECF.2004.1404977
Tsern-Huei Lee
Traffic shaping is an important technique for quality of service guarantees in a network that provides integrated services. It is often used in an access node to regulate user traffic submitted to the network. Since the leaky bucket algorithm has been selected by international standard organizations as the traffic policing algorithm, an ideal shaper should change the temporal characteristics of user traffic to conform to the criterion. It is well known that token bucket is equivalent to leaky bucket and is often used to name shapers that shape traffic in accordance with the leaky bucket criterion. However, in standard documents, the leaky bucket algorithm is described for a single traffic class. There is no discussion for multiple traffic classes. One possible way is to use multiple independent shapers such that each traffic class is regulated by one shaper independent of other traffic classes. This approach is simple but may not be reasonable. We propose to use multiple correlated token buckets to shape user traffic with multiple classes. In our proposed architecture, cheaper traffic classes can utilize the unused bandwidth subscribed for more expensive traffic classes. Besides, each traffic class is guaranteed a minimum bandwidth specified by its leaky bucket parameters.
{"title":"Correlated token bucket shapers for multiple traffic classes","authors":"Tsern-Huei Lee","doi":"10.1109/VETECF.2004.1404977","DOIUrl":"https://doi.org/10.1109/VETECF.2004.1404977","url":null,"abstract":"Traffic shaping is an important technique for quality of service guarantees in a network that provides integrated services. It is often used in an access node to regulate user traffic submitted to the network. Since the leaky bucket algorithm has been selected by international standard organizations as the traffic policing algorithm, an ideal shaper should change the temporal characteristics of user traffic to conform to the criterion. It is well known that token bucket is equivalent to leaky bucket and is often used to name shapers that shape traffic in accordance with the leaky bucket criterion. However, in standard documents, the leaky bucket algorithm is described for a single traffic class. There is no discussion for multiple traffic classes. One possible way is to use multiple independent shapers such that each traffic class is regulated by one shaper independent of other traffic classes. This approach is simple but may not be reasonable. We propose to use multiple correlated token buckets to shape user traffic with multiple classes. In our proposed architecture, cheaper traffic classes can utilize the unused bandwidth subscribed for more expensive traffic classes. Besides, each traffic class is guaranteed a minimum bandwidth specified by its leaky bucket parameters.","PeriodicalId":337062,"journal":{"name":"IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134325265","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}
In this paper, we investigate the performance of space-time codes for wireless transmission with the occurrance of partial-band noise jammers. The maximum likelihood (ML) decoding is derived together with several low-complexity subop- timal schemes. The design criteria of good space-time codes are presented with respect to the wireless jamming channels. Verified by the simulation results, the proposed system outperforms the conventional schemes in terms of both signal-to-noise ratio and bandwidth efficiency.
{"title":"Space-time coding for wireless channels with partial-band noise jammers","authors":"Chung-hsuan Wang, Kuei-Hua Li, Li-Der Jeng, Tsan-Ming Wu","doi":"10.1109/VETECF.2004.1400477","DOIUrl":"https://doi.org/10.1109/VETECF.2004.1400477","url":null,"abstract":"In this paper, we investigate the performance of space-time codes for wireless transmission with the occurrance of partial-band noise jammers. The maximum likelihood (ML) decoding is derived together with several low-complexity subop- timal schemes. The design criteria of good space-time codes are presented with respect to the wireless jamming channels. Verified by the simulation results, the proposed system outperforms the conventional schemes in terms of both signal-to-noise ratio and bandwidth efficiency.","PeriodicalId":337062,"journal":{"name":"IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128918883","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 : 2004-12-01DOI: 10.1093/ietcom/e89-b.2.556
Fumiaki Tsuzuki, T. Ohtsuki
Recently, superimposed pilot channel estimation has been proposed for wireless communications, where the pilot symbol sequence is superimposed on a data symbol sequence and transmitted together, and thus it has a high spectral efficiency. In this scheme, the receiver correlates the received signal sequence with the pilot symbol sequence, and obtains the channel estimate. However, the correlation between the pilot symbol sequence and the data symbol sequence deteriorates the channel estimation accuracy. The use of a longer frame leads to lower correlation, but also to a lower channel tracking capability. In this paper, we propose a selective superimposed pilot channel estimation scheme by selecting a pilot sequence that has a low correlation with the data symbol sequence from the set of the pilot sequences assigned to the transmitter. We show that the proposed channel estimation is superior to the conventional superimposed channel estimation (pilot=1), and the proposed scheme can achieve good channel estimation even under fast fading environments.
{"title":"Channel estimation with selective superimposed pilot sequences under fast fading environments","authors":"Fumiaki Tsuzuki, T. Ohtsuki","doi":"10.1093/ietcom/e89-b.2.556","DOIUrl":"https://doi.org/10.1093/ietcom/e89-b.2.556","url":null,"abstract":"Recently, superimposed pilot channel estimation has been proposed for wireless communications, where the pilot symbol sequence is superimposed on a data symbol sequence and transmitted together, and thus it has a high spectral efficiency. In this scheme, the receiver correlates the received signal sequence with the pilot symbol sequence, and obtains the channel estimate. However, the correlation between the pilot symbol sequence and the data symbol sequence deteriorates the channel estimation accuracy. The use of a longer frame leads to lower correlation, but also to a lower channel tracking capability. In this paper, we propose a selective superimposed pilot channel estimation scheme by selecting a pilot sequence that has a low correlation with the data symbol sequence from the set of the pilot sequences assigned to the transmitter. We show that the proposed channel estimation is superior to the conventional superimposed channel estimation (pilot=1), and the proposed scheme can achieve good channel estimation even under fast fading environments.","PeriodicalId":337062,"journal":{"name":"IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126609992","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 : 2004-12-01DOI: 10.1109/VETECF.2004.1405081
M. Nezafat, M. Kaveh, H. Tsuji, T. Fukagawa
In this paper, we present "subspace matching localization" as a technique for localizing non-cooperative transmitters in a microcellular environment dominated by non-line-of-sight (NLOS) propagation. using one base station that is equipped with one antenna array. The proposed method takes advantage of the dissimilarities in the multipath propagation characteristics of distinct locations in such an environment and site-specific ray tracing models to localize a transmitter. Issues regarding the coherency or non-coherency of multipath signals and effects of spatial smoothing on subspace matching localization are also addressed.
{"title":"Subspace matching localization: a practical approach to mobile user localization in microcellular environments","authors":"M. Nezafat, M. Kaveh, H. Tsuji, T. Fukagawa","doi":"10.1109/VETECF.2004.1405081","DOIUrl":"https://doi.org/10.1109/VETECF.2004.1405081","url":null,"abstract":"In this paper, we present \"subspace matching localization\" as a technique for localizing non-cooperative transmitters in a microcellular environment dominated by non-line-of-sight (NLOS) propagation. using one base station that is equipped with one antenna array. The proposed method takes advantage of the dissimilarities in the multipath propagation characteristics of distinct locations in such an environment and site-specific ray tracing models to localize a transmitter. Issues regarding the coherency or non-coherency of multipath signals and effects of spatial smoothing on subspace matching localization are also addressed.","PeriodicalId":337062,"journal":{"name":"IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123885316","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 : 2004-12-01DOI: 10.1109/VETECF.2004.1404717
S.H. Shah, K. Nahrstedt
Channel characteristics in multi-cell IEEE 802.11 wireless LANs are different front those in single-cell environments due to cross-channel interference. The IEEE 802.11 protocol does not have any provisions for rate guarantees in the presence of contention, fading and interference effects. We monitor these location-dependent effects distributedly at each wireless host and use a centralized bandwidth manager to allocate bandwidth to all flows in a co-ordinated manner. Using the mobile hosts' location, the bandwidth manager can also take advantage of spatial reuse to increase channel capacity. Our results show that we are able to detect and adapt to changing channel conditions well, and thus ensure a high level of throughput fairness among the flows.
{"title":"Channel-aware throughput fairness in multi-cell wireless LANs","authors":"S.H. Shah, K. Nahrstedt","doi":"10.1109/VETECF.2004.1404717","DOIUrl":"https://doi.org/10.1109/VETECF.2004.1404717","url":null,"abstract":"Channel characteristics in multi-cell IEEE 802.11 wireless LANs are different front those in single-cell environments due to cross-channel interference. The IEEE 802.11 protocol does not have any provisions for rate guarantees in the presence of contention, fading and interference effects. We monitor these location-dependent effects distributedly at each wireless host and use a centralized bandwidth manager to allocate bandwidth to all flows in a co-ordinated manner. Using the mobile hosts' location, the bandwidth manager can also take advantage of spatial reuse to increase channel capacity. Our results show that we are able to detect and adapt to changing channel conditions well, and thus ensure a high level of throughput fairness among the flows.","PeriodicalId":337062,"journal":{"name":"IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124650219","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 : 2004-12-01DOI: 10.1109/VETECF.2004.1404897
S. Tsai, Yuan-Pei Lin, C.-C. Jay Kuo
A new code selection scheme is proposed to reduce the MAI of the approximately MAI-free OFDM transceiver that is known as repetitively coded multicarrier CDMA (RCMC-CDMA). If we use M/2 symmetric codewords or anti-symmetric codewords of the M Hadamard-Walsh codes, then the MAI of the system can be greatly reduced. With this code selection scheme, the requirement of a sufficiently large number of subchannels to achieve the MAI-free property can be relaxed so that the approximately MAI-free property still holds when the number of subchannels is relatively small.
{"title":"Enhanced performance for an approximately MAI-free multiaccess OFDM transceiver by code selection","authors":"S. Tsai, Yuan-Pei Lin, C.-C. Jay Kuo","doi":"10.1109/VETECF.2004.1404897","DOIUrl":"https://doi.org/10.1109/VETECF.2004.1404897","url":null,"abstract":"A new code selection scheme is proposed to reduce the MAI of the approximately MAI-free OFDM transceiver that is known as repetitively coded multicarrier CDMA (RCMC-CDMA). If we use M/2 symmetric codewords or anti-symmetric codewords of the M Hadamard-Walsh codes, then the MAI of the system can be greatly reduced. With this code selection scheme, the requirement of a sufficiently large number of subchannels to achieve the MAI-free property can be relaxed so that the approximately MAI-free property still holds when the number of subchannels is relatively small.","PeriodicalId":337062,"journal":{"name":"IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115874085","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 : 2004-12-01DOI: 10.1093/ietcom/e89-b.3.914
K. Honjo, T. Ohtsuki
Recently, MIMO spatial multiplexing systems have attracted a lot of attention because of their high spectral efficiencies. In MIMO spatial multiplexing systems, maximum likelihood detection (MLD) is known as an optimal method for signal detection in terms of bit error rate (BER). However, the main drawback of MLD is its high complexity. In this paper, we propose two reduced complexity signal detection schemes. One combines the minimum mean square error (MMSE) detection and MLD based on the estimated signal to interference plus noise ratio (SINR). The other combines the ordered successive MMSE detection (OSD) and MLD based on the estimated SINR. We refer to these detection schemes as MMSE-MLD and OSD-MLD, respectively. We show by simulation results that the proposed MMSE-MLD and OSD-MLD can attain almost identical performance to that of MLD, with less complexity.
{"title":"Computational complexity reduction of MLD based on SINR in MIMO spatial multiplexing systems","authors":"K. Honjo, T. Ohtsuki","doi":"10.1093/ietcom/e89-b.3.914","DOIUrl":"https://doi.org/10.1093/ietcom/e89-b.3.914","url":null,"abstract":"Recently, MIMO spatial multiplexing systems have attracted a lot of attention because of their high spectral efficiencies. In MIMO spatial multiplexing systems, maximum likelihood detection (MLD) is known as an optimal method for signal detection in terms of bit error rate (BER). However, the main drawback of MLD is its high complexity. In this paper, we propose two reduced complexity signal detection schemes. One combines the minimum mean square error (MMSE) detection and MLD based on the estimated signal to interference plus noise ratio (SINR). The other combines the ordered successive MMSE detection (OSD) and MLD based on the estimated SINR. We refer to these detection schemes as MMSE-MLD and OSD-MLD, respectively. We show by simulation results that the proposed MMSE-MLD and OSD-MLD can attain almost identical performance to that of MLD, with less complexity.","PeriodicalId":337062,"journal":{"name":"IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125499555","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 : 2004-12-01DOI: 10.1109/VETECF.2004.1400404
Mustafa Cenk, Gursoy H Vincent Poor, Sergio Verdú
Transmission of information over noncoherent Rician fading channels using M-ary orthogonal on/off FSK (OOFSK) signaling with phase modulation is considered. The capacity of this signaling scheme is obtained both for finite M and as M tends to infinity. Power efficiency is investigated when the transmitter is subject to a peak-to-average power ratio (PAR) limitation or a peak power limitation. It is shown that, under PAR limitation, in contrast to average power limited systems, the minimum bit energy is not always achieved at zero spectral efficiency. It is concluded that, in these cases, operating at very low spectral efficiency should be avoided. On the other hand, it is demonstrated that if there is only a peak power limitation, power efficiency improves as one operates with smaller SNR and vanishing duty factor.
{"title":"Power efficiency of joint frequency-phase modulation in the low-SNR regime over noncoherent Rician channels","authors":"Mustafa Cenk, Gursoy H Vincent Poor, Sergio Verdú","doi":"10.1109/VETECF.2004.1400404","DOIUrl":"https://doi.org/10.1109/VETECF.2004.1400404","url":null,"abstract":"Transmission of information over noncoherent Rician fading channels using M-ary orthogonal on/off FSK (OOFSK) signaling with phase modulation is considered. The capacity of this signaling scheme is obtained both for finite M and as M tends to infinity. Power efficiency is investigated when the transmitter is subject to a peak-to-average power ratio (PAR) limitation or a peak power limitation. It is shown that, under PAR limitation, in contrast to average power limited systems, the minimum bit energy is not always achieved at zero spectral efficiency. It is concluded that, in these cases, operating at very low spectral efficiency should be avoided. On the other hand, it is demonstrated that if there is only a peak power limitation, power efficiency improves as one operates with smaller SNR and vanishing duty factor.","PeriodicalId":337062,"journal":{"name":"IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126661404","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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