Pub Date : 2008-03-05DOI: 10.1109/RWS.2008.4463480
T. Khanzada, A. Ali, A. Omar
Single Carrier Transmission (SCT) is a competing technique for Orthogonal Frequency Division Multiplexing (OFDM) in Broadband Wireless Systems (BWS). Recent developments in Frequency Domain Fqualization (FDE) using Decision Feedback Equalization (DFE) have greatly improved the system based on the SC technique. This paper presents the comparison of two different variants of both OFDM and SCT techniques, namely OFDM-Cyclic Prefix (OFDM-CP), OFDM-Zero Padding (OFDM-ZP), SC-CP and SC-ZP. SC variants are simulated with Linear Equalizer(LE) and DFE. We have simulated all four techniques for different flat and frequency selective channels. A new block DFE structure is presented which iteratively improves itself and performs better as we increase the number of iterations. Comparison results for BER simulations of both variants of OFDM and SC with LE and DFE verify the supremacy of CP versions of SC-LE and SC-DFE over OFDM-CP and OFDM-ZP.
{"title":"A study of variable channel length for single carrier transmission with decision feedback equalizer","authors":"T. Khanzada, A. Ali, A. Omar","doi":"10.1109/RWS.2008.4463480","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463480","url":null,"abstract":"Single Carrier Transmission (SCT) is a competing technique for Orthogonal Frequency Division Multiplexing (OFDM) in Broadband Wireless Systems (BWS). Recent developments in Frequency Domain Fqualization (FDE) using Decision Feedback Equalization (DFE) have greatly improved the system based on the SC technique. This paper presents the comparison of two different variants of both OFDM and SCT techniques, namely OFDM-Cyclic Prefix (OFDM-CP), OFDM-Zero Padding (OFDM-ZP), SC-CP and SC-ZP. SC variants are simulated with Linear Equalizer(LE) and DFE. We have simulated all four techniques for different flat and frequency selective channels. A new block DFE structure is presented which iteratively improves itself and performs better as we increase the number of iterations. Comparison results for BER simulations of both variants of OFDM and SC with LE and DFE verify the supremacy of CP versions of SC-LE and SC-DFE over OFDM-CP and OFDM-ZP.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128416910","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463568
V. Desai, J. Kepler, F. Vook
Transmit adaptive beamforming can be applied on the subcarriers of an OFDM system to obtain a coherent processing gain at the receiver. The IEEE 802.16e-2005 standard for mobile broadband wireless access contains signaling strategies that facilitate the use of downlink adaptive beam- forming which leverages time-division duplex (TDD) channel reciprocity. Motorola Labs has developed an experimental mobile multi-antenna OFDM system that implements a realtime, adaptive beamformer that uses these strategies. This paper describes key components and parameters of this experimental system and describes the results of field experiments that show the performance gains realized by this platform.
{"title":"Field data showing the downlink adaptive beamforming gains in an experimental IEEE 802.16e-2005 OFDMA system","authors":"V. Desai, J. Kepler, F. Vook","doi":"10.1109/RWS.2008.4463568","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463568","url":null,"abstract":"Transmit adaptive beamforming can be applied on the subcarriers of an OFDM system to obtain a coherent processing gain at the receiver. The IEEE 802.16e-2005 standard for mobile broadband wireless access contains signaling strategies that facilitate the use of downlink adaptive beam- forming which leverages time-division duplex (TDD) channel reciprocity. Motorola Labs has developed an experimental mobile multi-antenna OFDM system that implements a realtime, adaptive beamformer that uses these strategies. This paper describes key components and parameters of this experimental system and describes the results of field experiments that show the performance gains realized by this platform.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130803846","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463613
N. Sasho, K. Minami, H. Fujita, T. Takahashi, K. Iimura, M. Abe, A. Yasuda
We have developed a fully integrated 0.25 mum SiGe-BiCMOS transceiver with a power amplifier (PA), transmit / receive switch (T/R SW), orthogonal modulator / demodulator, received signal strength indicator (RSSI), and phase locked loop (PLL) for Dedicated Short Range Communications (DSRC) mobile terminals with Amplifier Shift Keying (ASK) and Pi/4- shifted Quadrature Phase Shift Keying (Pi/4-QPSK) dual-mode modulation. Transmitter architecture is based on the sliding-IF topology using 4.6 GHz VCO and a 1/4 divider. Receiver architecture is based on the fixed-IF super-heterodyne. For image spurious rejection in the transmitter, a passive band elimination filter (BEF) comprised of a differential inductor is implemented. The 3.1mm x 2.97 mm die is packaged in 5.8 mm x 5.8 mm 48 pin- VQFN.
我们开发了一种完全集成的0.25 μ m SiGe-BiCMOS收发器，带有功率放大器(PA)，发射/接收开关(T/R SW)，正交调制器/解调器，接收信号强度指示器(RSSI)和锁相环(PLL)，用于专用短距离通信(DSRC)移动终端，具有放大器移位键控(ASK)和Pi/4移位正交相移键控(Pi/4- qpsk)双模调制。发射机架构基于滑动中频拓扑，使用4.6 GHz压控振荡器和1/4分频器。接收机结构基于固定中频超外差。为了抑制发射机中的图像杂散，实现了由差动电感组成的无源带消除滤波器。3.1mm x 2.97 mm芯片封装在5.8 mm x 5.8 mm 48引脚- VQFN中。
{"title":"Single-chip 5.8GHz DSRC transceiver with dual-mode of ASK and Pi/4-QPSK","authors":"N. Sasho, K. Minami, H. Fujita, T. Takahashi, K. Iimura, M. Abe, A. Yasuda","doi":"10.1109/RWS.2008.4463613","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463613","url":null,"abstract":"We have developed a fully integrated 0.25 mum SiGe-BiCMOS transceiver with a power amplifier (PA), transmit / receive switch (T/R SW), orthogonal modulator / demodulator, received signal strength indicator (RSSI), and phase locked loop (PLL) for Dedicated Short Range Communications (DSRC) mobile terminals with Amplifier Shift Keying (ASK) and Pi/4- shifted Quadrature Phase Shift Keying (Pi/4-QPSK) dual-mode modulation. Transmitter architecture is based on the sliding-IF topology using 4.6 GHz VCO and a 1/4 divider. Receiver architecture is based on the fixed-IF super-heterodyne. For image spurious rejection in the transmitter, a passive band elimination filter (BEF) comprised of a differential inductor is implemented. The 3.1mm x 2.97 mm die is packaged in 5.8 mm x 5.8 mm 48 pin- VQFN.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129516644","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463575
S. Bieder, L. Haring, A. Czylwik
The capacity of a WCDMA-based cellular system like a UMTS-FDD network can be highly improved by utilizing the smart antenna concept. The received signal power of each link in the entire network can be increased by employing antenna arrays at the base station side and performing beamforming. Since the characteristics of a single antenna element have a strong influence on the amount of achievable capacity improvement, close-to-reality investigations on the network capacity must incorporate realistic antenna element characteristics. In this contribution, a UMTS-FDD network equipped with smart antennas at the base stations is analyzed on system level. Thereby, the focus lies on the impact of uncertainties in antenna position and alignment on the network capacity. Furthermore, the effect of different uplink and downlink carrier frequencies on the beamforming performance is analyzed. A simplified beamforming approach to overcome this effect is presented.
{"title":"Capacity of UMTS-FDD-based cellular systems with smart antennas in presence of position and alignment errors","authors":"S. Bieder, L. Haring, A. Czylwik","doi":"10.1109/RWS.2008.4463575","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463575","url":null,"abstract":"The capacity of a WCDMA-based cellular system like a UMTS-FDD network can be highly improved by utilizing the smart antenna concept. The received signal power of each link in the entire network can be increased by employing antenna arrays at the base station side and performing beamforming. Since the characteristics of a single antenna element have a strong influence on the amount of achievable capacity improvement, close-to-reality investigations on the network capacity must incorporate realistic antenna element characteristics. In this contribution, a UMTS-FDD network equipped with smart antennas at the base stations is analyzed on system level. Thereby, the focus lies on the impact of uncertainties in antenna position and alignment on the network capacity. Furthermore, the effect of different uplink and downlink carrier frequencies on the beamforming performance is analyzed. A simplified beamforming approach to overcome this effect is presented.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130914524","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463530
S.-l.S. Yang, A. Kishk, Kai-fong Lee, K. Luk, H. Lai
An antenna that is capable of exciting four different kinds of linearly polarized waves across an overlapped frequency band by four independent feeding ports is presented. The four polarizations embrace the x- and y-polarized waves which have broadside patterns and the thetas and phi-polarized waves which have conical patterns. The x- and y-polarizations (TMH mode) and the thetas-polarization (TM02 mode) are achieved by exciting a circular patch with four shorting posts and five L-shaped probe feeds, while the phi-polarization is achieved by exciting four slots cut on the patch to produce radial magnetic currents. The performance of the antenna is studied numerically and experimentally. A prototype antenna is built and it achieves four polarizations overlapped at about 2.1 GHz, a gain of about 4 dBi for the two conical waves, and a gain of about 11 dBi for the two broadside waves.
{"title":"The design of microstrip patch antenna with four polarizations","authors":"S.-l.S. Yang, A. Kishk, Kai-fong Lee, K. Luk, H. Lai","doi":"10.1109/RWS.2008.4463530","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463530","url":null,"abstract":"An antenna that is capable of exciting four different kinds of linearly polarized waves across an overlapped frequency band by four independent feeding ports is presented. The four polarizations embrace the x- and y-polarized waves which have broadside patterns and the thetas and phi-polarized waves which have conical patterns. The x- and y-polarizations (TMH mode) and the thetas-polarization (TM02 mode) are achieved by exciting a circular patch with four shorting posts and five L-shaped probe feeds, while the phi-polarization is achieved by exciting four slots cut on the patch to produce radial magnetic currents. The performance of the antenna is studied numerically and experimentally. A prototype antenna is built and it achieves four polarizations overlapped at about 2.1 GHz, a gain of about 4 dBi for the two conical waves, and a gain of about 11 dBi for the two broadside waves.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128955741","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463560
Yu Zhou, Y. Rong, Hyeong-Ah Choi, Jae-Hoon Kim, JungKyo Sohn, Hyeong-In Choi
The complementary characteristics of 3 G cellular networks (such as UMTS) and IEEE's 802.11 wireless LANs (WLANs) have stimulated intensive research efforts to integrate UMTS and WLAN networks. In such integrated networks, a mobile station is able to switch between UMTS and WLAN networks based on various network parameters such as network throughput, packet delay and other network or user quality criteria. In this paper, we develop a utility-based access selection algorithm targeted to achieve load balancing between UMTS and WLAN networks. The performance of our algorithm is evaluated using OPNET with dual-mode mobile stations.
{"title":"Utility-based load balancing in WLAN/UMTS internetworking systems","authors":"Yu Zhou, Y. Rong, Hyeong-Ah Choi, Jae-Hoon Kim, JungKyo Sohn, Hyeong-In Choi","doi":"10.1109/RWS.2008.4463560","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463560","url":null,"abstract":"The complementary characteristics of 3 G cellular networks (such as UMTS) and IEEE's 802.11 wireless LANs (WLANs) have stimulated intensive research efforts to integrate UMTS and WLAN networks. In such integrated networks, a mobile station is able to switch between UMTS and WLAN networks based on various network parameters such as network throughput, packet delay and other network or user quality criteria. In this paper, we develop a utility-based access selection algorithm targeted to achieve load balancing between UMTS and WLAN networks. The performance of our algorithm is evaluated using OPNET with dual-mode mobile stations.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114317328","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463447
T. Kuri, Hiroyuki Toda, Ken-ichi Kitayama
Dense wavelength division multiplexed (DWDM) access network which allows to co-exists analog radio-over-fiber (RoF) and digital fiber-to-the-home (FTTH) systems is investigated. Focuses are on the enabling techniques such as optical-frequency-interleaved DWDM grid assignment, supercontinuum multi-wavelength light source, multi-band RoF and digital optical signals transmission, and optical path routing for dynamic channel allocation for wireless services.
{"title":"Radio over fiber: DWDM-based analog/digital access networking and its enabling technologies","authors":"T. Kuri, Hiroyuki Toda, Ken-ichi Kitayama","doi":"10.1109/RWS.2008.4463447","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463447","url":null,"abstract":"Dense wavelength division multiplexed (DWDM) access network which allows to co-exists analog radio-over-fiber (RoF) and digital fiber-to-the-home (FTTH) systems is investigated. Focuses are on the enabling techniques such as optical-frequency-interleaved DWDM grid assignment, supercontinuum multi-wavelength light source, multi-band RoF and digital optical signals transmission, and optical path routing for dynamic channel allocation for wireless services.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"208 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122411225","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463429
K. Joshin, T. Kikkawa
We report a current status of high-power GaN HEMTs for high-power and high-efficiency amplifiers with higher efficiency by 5% especially at a backed-off region than the conventional GaN HEMTs. First, we introduce our specific device structure GaN HEMT with dispersion-free I-V characteristics, low Idsq-drift and high reliability. Record average drain efficiency of over 50% and linear gain of 17.2 dB were obtained at an output power of 45 dBm and 2.5 GHz. Next, we discuss their reliability with high-temperature life tests resulting in their estimated life of over 1 times 106 hours at Tj of 200degC. Finally, we describe the next generation GaN HEMTs for millimeter-wave applications.
{"title":"High-power and high-efficiency GaN HEMT amplifiers","authors":"K. Joshin, T. Kikkawa","doi":"10.1109/RWS.2008.4463429","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463429","url":null,"abstract":"We report a current status of high-power GaN HEMTs for high-power and high-efficiency amplifiers with higher efficiency by 5% especially at a backed-off region than the conventional GaN HEMTs. First, we introduce our specific device structure GaN HEMT with dispersion-free I-V characteristics, low Idsq-drift and high reliability. Record average drain efficiency of over 50% and linear gain of 17.2 dB were obtained at an output power of 45 dBm and 2.5 GHz. Next, we discuss their reliability with high-temperature life tests resulting in their estimated life of over 1 times 106 hours at Tj of 200degC. Finally, we describe the next generation GaN HEMTs for millimeter-wave applications.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126082690","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463413
Kai Li, Xiaodong Wang
We investigate the optimal design of a multihop wireless mesh network equipped with multiple orthogonal wireless channels and multiple radios. Specifically, we focus on solutions that can efficiently utilize the limited resource to support multiple unicast applications by routing and network coding. We propose a cross-layer optimization framework where the broadcasting feature of the wireless environment, which plays an important role in realizing the achievable gain of network coding, is taken into account. Moreover, we propose a network code construction scheme based on linear programming, with which the possible achievable Coding+MAC gain could be significantly increased. The proposed network design based on cross-layer optimization results in significant increase in network throughput.
{"title":"Cross-layer design of mesh networks with network coding","authors":"Kai Li, Xiaodong Wang","doi":"10.1109/RWS.2008.4463413","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463413","url":null,"abstract":"We investigate the optimal design of a multihop wireless mesh network equipped with multiple orthogonal wireless channels and multiple radios. Specifically, we focus on solutions that can efficiently utilize the limited resource to support multiple unicast applications by routing and network coding. We propose a cross-layer optimization framework where the broadcasting feature of the wireless environment, which plays an important role in realizing the achievable gain of network coding, is taken into account. Moreover, we propose a network code construction scheme based on linear programming, with which the possible achievable Coding+MAC gain could be significantly increased. The proposed network design based on cross-layer optimization results in significant increase in network throughput.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122878819","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463425
O. Gunther, D. Steinbuch, O. Bruggemann, H. Jager, R. Weigel
The DC-offset compensation of a monostatic FMCW-radar transceiver using transmission line (TL) length optimization is proposed. This approach can be implemented on a 77 GHz SiGe MMIC (Monolithic Microwave Integrated Circuit) with no extra costs and does not degrade the sensitivity for immediate targets needed for the stop-and- go functionality of modern ACC (Adaptive Cruise Control) systems. The theory of the DC-offset generation will be discussed and a network analysis of the transceiver will be presented. It is shown that the compensation is possible over a wide range of circuit imperfection values.
{"title":"DC-offset compensation of a 77 GHz monostatic FMCW-radar transceiver for automotive application","authors":"O. Gunther, D. Steinbuch, O. Bruggemann, H. Jager, R. Weigel","doi":"10.1109/RWS.2008.4463425","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463425","url":null,"abstract":"The DC-offset compensation of a monostatic FMCW-radar transceiver using transmission line (TL) length optimization is proposed. This approach can be implemented on a 77 GHz SiGe MMIC (Monolithic Microwave Integrated Circuit) with no extra costs and does not degrade the sensitivity for immediate targets needed for the stop-and- go functionality of modern ACC (Adaptive Cruise Control) systems. The theory of the DC-offset generation will be discussed and a network analysis of the transceiver will be presented. It is shown that the compensation is possible over a wide range of circuit imperfection values.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126976903","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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