Pub Date : 1997-09-01DOI: 10.1109/PIMRC.1997.631179
M. Reed, P. Alexander, J. Asenstorfer, C. Schlegel
This paper discusses a code-division multiple access (CDMA) iterative multi-user receiver with forward error control (FEC) decoding. The maximum a-posteriori probability (MAP) criteria is used to derive the receiver. The decoding is done using a turbo-code decoder with modifications which are discussed. Iterations of the system are used to attain large performance improvements over conventional systems.
{"title":"Near single user performance using iterative multi-user detection for CDMA with turbo-code decoders","authors":"M. Reed, P. Alexander, J. Asenstorfer, C. Schlegel","doi":"10.1109/PIMRC.1997.631179","DOIUrl":"https://doi.org/10.1109/PIMRC.1997.631179","url":null,"abstract":"This paper discusses a code-division multiple access (CDMA) iterative multi-user receiver with forward error control (FEC) decoding. The maximum a-posteriori probability (MAP) criteria is used to derive the receiver. The decoding is done using a turbo-code decoder with modifications which are discussed. Iterations of the system are used to attain large performance improvements over conventional systems.","PeriodicalId":362340,"journal":{"name":"Proceedings of 8th International Symposium on Personal, Indoor and Mobile Radio Communications - PIMRC '97","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128055769","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 : 1997-09-01DOI: 10.1109/PIMRC.1997.631139
A. Zahedi, K. Pahlavan
The capacity of a carrier sense multiple access (CSMA) wireless LAN with voice and data services using the TCP/IP protocol is analyzed to obtain a lower bound for the capacity of the 802.11 wireless networks with voice and data services. The voice traffic is given higher priority over the data traffic to accommodate the delay requirement for an acceptable quality of service (QoS). This is implemented by assigning the TCP protocol for the data and the UDP protocol for the voice. The relationship between the data throughput and the number of the voice users supported in this environment is analyzed. The improved multi-band excitation (IMBE) voice encoding technique, proposed for the APCO-25 and used in the INMARSAT-M and AUSSAT mobile satellite communications, is adopted to provide a low transmission rate with an acceptable quality.
{"title":"Voice and data integration on TCP/IP wireless networks","authors":"A. Zahedi, K. Pahlavan","doi":"10.1109/PIMRC.1997.631139","DOIUrl":"https://doi.org/10.1109/PIMRC.1997.631139","url":null,"abstract":"The capacity of a carrier sense multiple access (CSMA) wireless LAN with voice and data services using the TCP/IP protocol is analyzed to obtain a lower bound for the capacity of the 802.11 wireless networks with voice and data services. The voice traffic is given higher priority over the data traffic to accommodate the delay requirement for an acceptable quality of service (QoS). This is implemented by assigning the TCP protocol for the data and the UDP protocol for the voice. The relationship between the data throughput and the number of the voice users supported in this environment is analyzed. The improved multi-band excitation (IMBE) voice encoding technique, proposed for the APCO-25 and used in the INMARSAT-M and AUSSAT mobile satellite communications, is adopted to provide a low transmission rate with an acceptable quality.","PeriodicalId":362340,"journal":{"name":"Proceedings of 8th International Symposium on Personal, Indoor and Mobile Radio Communications - PIMRC '97","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127103387","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 : 1997-09-01DOI: 10.1109/PIMRC.1997.631109
M. Williamson, G. Athanasiadou, A. Nix
This paper investigates the nature of the indoor radio channel at 60 GHz, with regard to its use for future high bit-rate broadband wireless networks. It is proposed that, for operation in the millimetre-wave indoor channel, directional antennas can be used to mitigate multipath effects, thus reducing the need for complex equalisation or multi-carrier techniques. An image based, ray-tracing prediction model is used to study the channel characteristics and to analyse the variation in received power, RMS delay spread and k-factor within a typical operating environment. The performances of different antenna combinations are investigated and narrowbeam, suitably aligned antennas are shown to reduce received delay spread for both LOS and non-LOS locations. The effects of non-optimal antenna alignment are observed, and system outage is determined for certain system design criteria. The results suggest that it will feasible to combat multipath effects using switched-beam directional antennas.
{"title":"Investigating the effects of antenna directivity on wireless indoor communication at 60 GHz","authors":"M. Williamson, G. Athanasiadou, A. Nix","doi":"10.1109/PIMRC.1997.631109","DOIUrl":"https://doi.org/10.1109/PIMRC.1997.631109","url":null,"abstract":"This paper investigates the nature of the indoor radio channel at 60 GHz, with regard to its use for future high bit-rate broadband wireless networks. It is proposed that, for operation in the millimetre-wave indoor channel, directional antennas can be used to mitigate multipath effects, thus reducing the need for complex equalisation or multi-carrier techniques. An image based, ray-tracing prediction model is used to study the channel characteristics and to analyse the variation in received power, RMS delay spread and k-factor within a typical operating environment. The performances of different antenna combinations are investigated and narrowbeam, suitably aligned antennas are shown to reduce received delay spread for both LOS and non-LOS locations. The effects of non-optimal antenna alignment are observed, and system outage is determined for certain system design criteria. The results suggest that it will feasible to combat multipath effects using switched-beam directional antennas.","PeriodicalId":362340,"journal":{"name":"Proceedings of 8th International Symposium on Personal, Indoor and Mobile Radio Communications - PIMRC '97","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114076130","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 : 1997-09-01DOI: 10.1109/PIMRC.1997.630898
W. Hollemans, R. Prasad, A. Kegel
The performance of cellular digital mobile radio systems is investigated using quadrature amplitude modulation (4-QAM) and differential phase shift keying (DPSK) in a frequency nonselective Rayleigh fading environment with lognormal shadowing, including the effects of (white) Gaussian noise, narrow-band impulsive noise/interference (Middleton's Class A model), and cochannel interference. The performance is analyzed in terms of probability of bit error. The UHF groundwave propagation law is introduced by considering the local mean power to be inversely proportional to the fourth power of propagation distance. To investigate the improvement in performance the influence of selection diversity and maximal ratio combining on the bit error probability is analyzed. It has been found that shadowing significantly affects the bit error performance. Application of selection diversity or maximal ratio combining results in important improvement of system performance. Selection diversity gives better results than maximal ratio combining for low signal-to-noise ratios. Results of our analysis show maximal ratio combining is not that sensitive to unequal branch signal-to-noise-plus-interference ratio.
{"title":"Performance analysis of cellular digital mobile radio systems including diversity techniques","authors":"W. Hollemans, R. Prasad, A. Kegel","doi":"10.1109/PIMRC.1997.630898","DOIUrl":"https://doi.org/10.1109/PIMRC.1997.630898","url":null,"abstract":"The performance of cellular digital mobile radio systems is investigated using quadrature amplitude modulation (4-QAM) and differential phase shift keying (DPSK) in a frequency nonselective Rayleigh fading environment with lognormal shadowing, including the effects of (white) Gaussian noise, narrow-band impulsive noise/interference (Middleton's Class A model), and cochannel interference. The performance is analyzed in terms of probability of bit error. The UHF groundwave propagation law is introduced by considering the local mean power to be inversely proportional to the fourth power of propagation distance. To investigate the improvement in performance the influence of selection diversity and maximal ratio combining on the bit error probability is analyzed. It has been found that shadowing significantly affects the bit error performance. Application of selection diversity or maximal ratio combining results in important improvement of system performance. Selection diversity gives better results than maximal ratio combining for low signal-to-noise ratios. Results of our analysis show maximal ratio combining is not that sensitive to unequal branch signal-to-noise-plus-interference ratio.","PeriodicalId":362340,"journal":{"name":"Proceedings of 8th International Symposium on Personal, Indoor and Mobile Radio Communications - PIMRC '97","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122501189","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 : 1997-09-01DOI: 10.1109/PIMRC.1997.626995
C. Tellambura, I. Johnson, Y. Guo, S. Barton
To reduce the effects of intersymbol interference resulting from the dispersive nature of the indoor radio channel most HIPERLAN receivers will incorporate an adaptive equaliser. The computational complexity of several equaliser algorithms is estimated. The effect of frequency offset between the transmitter and receiver on the performance of such an equaliser is investigated. By employing a decision feedback equaliser incorporating a second order phase locked loop, the effect of both the intersymbol interference and frequency offset can be significantly reduced. Using such a technique, the packet error ratio (PER) of a HIPERLAN radio link in a multipath channel is found by simulation.
{"title":"Equalisation and frequency offset correction for HIPERLAN","authors":"C. Tellambura, I. Johnson, Y. Guo, S. Barton","doi":"10.1109/PIMRC.1997.626995","DOIUrl":"https://doi.org/10.1109/PIMRC.1997.626995","url":null,"abstract":"To reduce the effects of intersymbol interference resulting from the dispersive nature of the indoor radio channel most HIPERLAN receivers will incorporate an adaptive equaliser. The computational complexity of several equaliser algorithms is estimated. The effect of frequency offset between the transmitter and receiver on the performance of such an equaliser is investigated. By employing a decision feedback equaliser incorporating a second order phase locked loop, the effect of both the intersymbol interference and frequency offset can be significantly reduced. Using such a technique, the packet error ratio (PER) of a HIPERLAN radio link in a multipath channel is found by simulation.","PeriodicalId":362340,"journal":{"name":"Proceedings of 8th International Symposium on Personal, Indoor and Mobile Radio Communications - PIMRC '97","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122619776","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 : 1997-09-01DOI: 10.1109/PIMRC.1997.626994
J. Wen, Kuo-Gen Hsu, Ethan Chen, J. Wen
Power assignment schemes are man-made method used to enhance the capture effect of contention-based multiple access systems while Rayleigh fading, near/far effect and shadow fading are natural factors that cause the capture effect in radio communications. The combined impact of natural and man-made capture effects on the performance of a cellular system with finite population is studied. A Markov model is used to carry out an analysis of the system throughput and delay. Some numerical calculations are used to demonstrate the degree of performance improvement.
{"title":"Performance evaluation of random power assignment scheme on cellular mobile communications with finite population","authors":"J. Wen, Kuo-Gen Hsu, Ethan Chen, J. Wen","doi":"10.1109/PIMRC.1997.626994","DOIUrl":"https://doi.org/10.1109/PIMRC.1997.626994","url":null,"abstract":"Power assignment schemes are man-made method used to enhance the capture effect of contention-based multiple access systems while Rayleigh fading, near/far effect and shadow fading are natural factors that cause the capture effect in radio communications. The combined impact of natural and man-made capture effects on the performance of a cellular system with finite population is studied. A Markov model is used to carry out an analysis of the system throughput and delay. Some numerical calculations are used to demonstrate the degree of performance improvement.","PeriodicalId":362340,"journal":{"name":"Proceedings of 8th International Symposium on Personal, Indoor and Mobile Radio Communications - PIMRC '97","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122986276","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 : 1997-09-01DOI: 10.1109/PIMRC.1997.631104
Detlef Mansel, Andreas Müller, C. Plenge
The DECT (Digital Enhanced Telecommunication System) is considered to be one of the prime candidates for the wireless local loop (WLL) and personal communication systems (PCS) as well. To test the DECT under real life conditions one of the new network operators, namely o.tel.o Kommunikationssysteme GmbH (former RWE Telliance GmbH), has set up a large field-trial system in Gelsenkirchen, Germany. A key issue is the spectrum needed for DECT as a WLL system, as the WLL system has to share the 20 MHz of DECT spectrum with all private systems, e.g. cordless phones and cordless private branch exchanges. A special "hot spot" test campaign within the Gelsenkirchen field-trial system is described. The public WLL and PCS systems were heavily loaded with traffic. In addition 35 private DECT telephones which generated a traffic load of approximately one Erlang each were set up in the hot spot area. The performance of the private and the public systems were measured. Test results show a very good performance of the private system and a good performance of the public system under this "hot spot" condition.
DECT(数字增强通信系统)被认为是无线本地环路(WLL)和个人通信系统(PCS)的主要候选者之一。为了在现实生活条件下测试DECT，一家新的网络运营商，即o. telo Kommunikationssysteme GmbH(原RWE Telliance GmbH)，已经在德国Gelsenkirchen建立了一个大型的现场试验系统。一个关键问题是DECT作为WLL系统所需的频谱，因为WLL系统必须与所有专用系统共享20mhz的DECT频谱，例如无绳电话和无绳专用分支交换机。描述了Gelsenkirchen田间试验系统中的一个特殊的“热点”测试活动。公共WLL和PCS系统的流量非常大。此外，在热点地区设置了35部私人DECT电话，每部电话产生大约一个Erlang的流量负荷。对私人和公共系统的表现进行了衡量。测试结果表明，在这种“热点”条件下，私有系统和公共系统的性能都很好。
{"title":"\"Hot spot\" trial for DECT as a WLL technology","authors":"Detlef Mansel, Andreas Müller, C. Plenge","doi":"10.1109/PIMRC.1997.631104","DOIUrl":"https://doi.org/10.1109/PIMRC.1997.631104","url":null,"abstract":"The DECT (Digital Enhanced Telecommunication System) is considered to be one of the prime candidates for the wireless local loop (WLL) and personal communication systems (PCS) as well. To test the DECT under real life conditions one of the new network operators, namely o.tel.o Kommunikationssysteme GmbH (former RWE Telliance GmbH), has set up a large field-trial system in Gelsenkirchen, Germany. A key issue is the spectrum needed for DECT as a WLL system, as the WLL system has to share the 20 MHz of DECT spectrum with all private systems, e.g. cordless phones and cordless private branch exchanges. A special \"hot spot\" test campaign within the Gelsenkirchen field-trial system is described. The public WLL and PCS systems were heavily loaded with traffic. In addition 35 private DECT telephones which generated a traffic load of approximately one Erlang each were set up in the hot spot area. The performance of the private and the public systems were measured. Test results show a very good performance of the private system and a good performance of the public system under this \"hot spot\" condition.","PeriodicalId":362340,"journal":{"name":"Proceedings of 8th International Symposium on Personal, Indoor and Mobile Radio Communications - PIMRC '97","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129004086","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 : 1997-09-01DOI: 10.1109/PIMRC.1997.627051
I. Rivas, L. Lopes
Radio-fibre microcellular networks are composed by small-size cells that make use of a fibre optic network for the conveyance of RF signals from a central controller to remote antennae at cellsite. This structure is particularly suitable to accomplish receiver and transmitter macrodiversity since the same RF channel can be transmitted and received through multiple ports, thus providing a large coverage area in which mobiles do not have to switch channels when roaming. This paper investigates the performance of multitransmitter diversity in fading channels, in noise and interference limited conditions. The problem differs from diversity reception in that signal combining is now non-coherent. Results are presented in terms of radio coverage and cochannel reuse efficiency firstly under Rayleigh fading only and secondly in a city street microcell environment. Simulcasting is an effective shadowing counteraction in noise conditions and achieves similar performance to no diversity in interference conditions.
{"title":"Transmitter macrodiversity in radio fibre microcellular networks","authors":"I. Rivas, L. Lopes","doi":"10.1109/PIMRC.1997.627051","DOIUrl":"https://doi.org/10.1109/PIMRC.1997.627051","url":null,"abstract":"Radio-fibre microcellular networks are composed by small-size cells that make use of a fibre optic network for the conveyance of RF signals from a central controller to remote antennae at cellsite. This structure is particularly suitable to accomplish receiver and transmitter macrodiversity since the same RF channel can be transmitted and received through multiple ports, thus providing a large coverage area in which mobiles do not have to switch channels when roaming. This paper investigates the performance of multitransmitter diversity in fading channels, in noise and interference limited conditions. The problem differs from diversity reception in that signal combining is now non-coherent. Results are presented in terms of radio coverage and cochannel reuse efficiency firstly under Rayleigh fading only and secondly in a city street microcell environment. Simulcasting is an effective shadowing counteraction in noise conditions and achieves similar performance to no diversity in interference conditions.","PeriodicalId":362340,"journal":{"name":"Proceedings of 8th International Symposium on Personal, Indoor and Mobile Radio Communications - PIMRC '97","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129371507","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 : 1997-09-01DOI: 10.1109/PIMRC.1997.627034
P. Karttunen, T. Laakso, Joseph Lilleberg
In future telecommunication systems, one of the most important ways to increase system capacity is to use adaptive antennas. They enable reception and transmission using narrow beams which drastically reduce interference for other users. The problem with the conventional adaptive tracking algorithms is that the adaptation performance is dictated by the choice of the convergence parameter or step size. We employ a multi-target tracking method and modify its tracking performance by an adaptive step size. The simulation results show that the proposed adaptive control of the convergence parameter gives fast convergence and small misadjustment errors, which cannot be combined by using fixed step size.
{"title":"Tracking of mobile users in a mobile communications system using adaptive convergence parameter","authors":"P. Karttunen, T. Laakso, Joseph Lilleberg","doi":"10.1109/PIMRC.1997.627034","DOIUrl":"https://doi.org/10.1109/PIMRC.1997.627034","url":null,"abstract":"In future telecommunication systems, one of the most important ways to increase system capacity is to use adaptive antennas. They enable reception and transmission using narrow beams which drastically reduce interference for other users. The problem with the conventional adaptive tracking algorithms is that the adaptation performance is dictated by the choice of the convergence parameter or step size. We employ a multi-target tracking method and modify its tracking performance by an adaptive step size. The simulation results show that the proposed adaptive control of the convergence parameter gives fast convergence and small misadjustment errors, which cannot be combined by using fixed step size.","PeriodicalId":362340,"journal":{"name":"Proceedings of 8th International Symposium on Personal, Indoor and Mobile Radio Communications - PIMRC '97","volume":"1952 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129105049","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 : 1997-09-01DOI: 10.1109/PIMRC.1997.627010
J. Mayer, J. Schlee, T. Weber
In the early 1990s investigations towards an air interface for UMTS and IMT2000 were started at the Research Group for RF Communications. The result is an air interface, which uses a combination of the multiple access schemes FDMA, TDMA and CDMA, and in which signal separation in the receiver is performed by joint detection (JD). The air interface is termed JD-CDMA and adopts the philosophy of the de facto world standard GSM to an extent as large as possible. The authors investigate which extensions of the existing GSM protocols are necessary to support JD-CDMA, and how JD-CDMA protocols can be implemented.
{"title":"Protocol and signalling aspects of joint detection CDMA","authors":"J. Mayer, J. Schlee, T. Weber","doi":"10.1109/PIMRC.1997.627010","DOIUrl":"https://doi.org/10.1109/PIMRC.1997.627010","url":null,"abstract":"In the early 1990s investigations towards an air interface for UMTS and IMT2000 were started at the Research Group for RF Communications. The result is an air interface, which uses a combination of the multiple access schemes FDMA, TDMA and CDMA, and in which signal separation in the receiver is performed by joint detection (JD). The air interface is termed JD-CDMA and adopts the philosophy of the de facto world standard GSM to an extent as large as possible. The authors investigate which extensions of the existing GSM protocols are necessary to support JD-CDMA, and how JD-CDMA protocols can be implemented.","PeriodicalId":362340,"journal":{"name":"Proceedings of 8th International Symposium on Personal, Indoor and Mobile Radio Communications - PIMRC '97","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115833335","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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