Pub Date : 2008-12-08DOI: 10.1109/PIMRC.2008.4699918
C. Rosenberg, Jun Luo, A. Girard
Wireless mesh networks are considered as a potentially attractive alternative to provide broadband access to users. They have been studied extensively by the research community since they raised a lot of new issues due to their unique characteristics. Here, we focus on scenarios where these networks are installed and managed to provide broadband access to a set of fixed nodes. While a lot of research has been done on this type of networks, there are very few insightful engineering results that can help network operators deploy and manage such networks. It is the objective of this paper to present some major engineering insights on such networks. We limit our scope to networks that are single rate and in which all nodes use the same transmit power. In particular, we quantify the advantage of multi-hop over single-hop. We illustrate the importance of multi-path routing over single path routing, and of optimal routing versus min-hop routing. We revisit the notion of spatial reuse. Finally we present results showing the importance of selecting an appropriate interference model.
{"title":"Engineering wireless mesh networks","authors":"C. Rosenberg, Jun Luo, A. Girard","doi":"10.1109/PIMRC.2008.4699918","DOIUrl":"https://doi.org/10.1109/PIMRC.2008.4699918","url":null,"abstract":"Wireless mesh networks are considered as a potentially attractive alternative to provide broadband access to users. They have been studied extensively by the research community since they raised a lot of new issues due to their unique characteristics. Here, we focus on scenarios where these networks are installed and managed to provide broadband access to a set of fixed nodes. While a lot of research has been done on this type of networks, there are very few insightful engineering results that can help network operators deploy and manage such networks. It is the objective of this paper to present some major engineering insights on such networks. We limit our scope to networks that are single rate and in which all nodes use the same transmit power. In particular, we quantify the advantage of multi-hop over single-hop. We illustrate the importance of multi-path routing over single path routing, and of optimal routing versus min-hop routing. We revisit the notion of spatial reuse. Finally we present results showing the importance of selecting an appropriate interference model.","PeriodicalId":125554,"journal":{"name":"2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129094231","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 : 2008-12-08DOI: 10.1109/PIMRC.2008.4699839
Yang Liu, L. Brunel, J. Boutros
In order to increase the performance of joint channel estimation and decoding through belief propagation on factor graphs, we approximate the distribution of channel estimate in the factor graph as a mixture of Gaussian distributions. The result is a continuous downward and upward message propagation in the factor graph instead of discrete probability distributions. Using continuous downward messages, the computation complexity of belief propagation is reduced without performance degradation. With both continuous upward and downward messages, belief propagation almost achieves the same performance as expectation-maximization under good initialization and outperforms it under bad initialization.
{"title":"Belief propagation with Gaussian approximation for joint channel estimation and decoding","authors":"Yang Liu, L. Brunel, J. Boutros","doi":"10.1109/PIMRC.2008.4699839","DOIUrl":"https://doi.org/10.1109/PIMRC.2008.4699839","url":null,"abstract":"In order to increase the performance of joint channel estimation and decoding through belief propagation on factor graphs, we approximate the distribution of channel estimate in the factor graph as a mixture of Gaussian distributions. The result is a continuous downward and upward message propagation in the factor graph instead of discrete probability distributions. Using continuous downward messages, the computation complexity of belief propagation is reduced without performance degradation. With both continuous upward and downward messages, belief propagation almost achieves the same performance as expectation-maximization under good initialization and outperforms it under bad initialization.","PeriodicalId":125554,"journal":{"name":"2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129120193","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 : 2008-12-08DOI: 10.1109/PIMRC.2008.4699540
V. Vassilakis, M. Logothetis
The call-level performance modelling and evaluation of 3G cellular networks is important for the proper network dimensioning and efficient use of the network resources, such as bandwidth and power. In the case of the wideband code division multiple access (W-CDMA) cellular networks, this task is complicated, not only because of the so called soft blocking, the multiple access interference (MAI) and the heterogeneous traffic, but also due to the handoff process. In this paper, we propose a new teletraffic model for the call-level analysis of handoff traffic in the uplink of W-CDMA networks where multiple services with finite number of traffic sources are accommodated. Parameters related to the soft blocking and MAI are included into the model. The proposed model is described by a discrete time Markov chain. An efficient recurrent formula for the calculation of the system state probabilities is derived. Based on this formula, blocking probabilities of both new and handoff calls are determined. The accuracy of the proposed model is evaluated through simulation and is found to be very satisfactory. Moreover, we show the necessity of distinguishing the handoff traffic from the new traffic, in respect of blocking probabilities.
{"title":"The Wireless Engset Multi-Rate Loss Model for the Handoff traffic analysis in W-CDMA networks","authors":"V. Vassilakis, M. Logothetis","doi":"10.1109/PIMRC.2008.4699540","DOIUrl":"https://doi.org/10.1109/PIMRC.2008.4699540","url":null,"abstract":"The call-level performance modelling and evaluation of 3G cellular networks is important for the proper network dimensioning and efficient use of the network resources, such as bandwidth and power. In the case of the wideband code division multiple access (W-CDMA) cellular networks, this task is complicated, not only because of the so called soft blocking, the multiple access interference (MAI) and the heterogeneous traffic, but also due to the handoff process. In this paper, we propose a new teletraffic model for the call-level analysis of handoff traffic in the uplink of W-CDMA networks where multiple services with finite number of traffic sources are accommodated. Parameters related to the soft blocking and MAI are included into the model. The proposed model is described by a discrete time Markov chain. An efficient recurrent formula for the calculation of the system state probabilities is derived. Based on this formula, blocking probabilities of both new and handoff calls are determined. The accuracy of the proposed model is evaluated through simulation and is found to be very satisfactory. Moreover, we show the necessity of distinguishing the handoff traffic from the new traffic, in respect of blocking probabilities.","PeriodicalId":125554,"journal":{"name":"2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126964390","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 : 2008-12-08DOI: 10.1109/PIMRC.2008.4699464
Yifan Chen, P. Rapajic
We explore the potential application of cognitive interrogator network (CIN) in remote monitoring of mobile subjects in domestic environments, where the ultra-wideband radio frequency identification (UWB-RFID) technique is considered for accurate source localization. We first present the CIN architecture in which the central base station (BS) continuously and intelligently customizes the illumination modes of the distributed transceivers in response to the systempsilas changing knowledge of the channel conditions and subject movements. Subsequently, the analytical results of the locating probability and time-of-arrival (TOA) estimation uncertainty for a large-scale CIN with randomly distributed interrogators are derived based upon the implemented cognitive intelligences. Finally, numerical examples are used to demonstrate the key effects of the proposed cognitions on the system performance.
{"title":"Ultra-wideband Cognitive Interrogator Network for indoor location tracking - part I: System architecture and network performance analysis","authors":"Yifan Chen, P. Rapajic","doi":"10.1109/PIMRC.2008.4699464","DOIUrl":"https://doi.org/10.1109/PIMRC.2008.4699464","url":null,"abstract":"We explore the potential application of cognitive interrogator network (CIN) in remote monitoring of mobile subjects in domestic environments, where the ultra-wideband radio frequency identification (UWB-RFID) technique is considered for accurate source localization. We first present the CIN architecture in which the central base station (BS) continuously and intelligently customizes the illumination modes of the distributed transceivers in response to the systempsilas changing knowledge of the channel conditions and subject movements. Subsequently, the analytical results of the locating probability and time-of-arrival (TOA) estimation uncertainty for a large-scale CIN with randomly distributed interrogators are derived based upon the implemented cognitive intelligences. Finally, numerical examples are used to demonstrate the key effects of the proposed cognitions on the system performance.","PeriodicalId":125554,"journal":{"name":"2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130582280","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 : 2008-12-08DOI: 10.1109/PIMRC.2008.4699535
A. A. Safonov, A. Lyakhov, E. Khorov
Beaconing is crucial to ensure many services in networks, especially with distributed MAC. Being the first standardized distributed MAC for WPANs, ECMA-368 utilizes beacons for device discovery, channel reservation, mobility support, etc. In this paper, we develop an analytical method to find the distribution of the time which devices need for channel switching caused by environment changes such as open/close door effect. Verified by simulation results, the analytical model gives optimistic or conservative estimations, depending on the used assumption. The proposed method may be used to find the best beaconing parameters, which minimize the pause in network operation caused by channel switch or other network re-arrangements, which is very important for delay-sensitive applications.
{"title":"Channel switch time distribution in ECMA-368 networks","authors":"A. A. Safonov, A. Lyakhov, E. Khorov","doi":"10.1109/PIMRC.2008.4699535","DOIUrl":"https://doi.org/10.1109/PIMRC.2008.4699535","url":null,"abstract":"Beaconing is crucial to ensure many services in networks, especially with distributed MAC. Being the first standardized distributed MAC for WPANs, ECMA-368 utilizes beacons for device discovery, channel reservation, mobility support, etc. In this paper, we develop an analytical method to find the distribution of the time which devices need for channel switching caused by environment changes such as open/close door effect. Verified by simulation results, the analytical model gives optimistic or conservative estimations, depending on the used assumption. The proposed method may be used to find the best beaconing parameters, which minimize the pause in network operation caused by channel switch or other network re-arrangements, which is very important for delay-sensitive applications.","PeriodicalId":125554,"journal":{"name":"2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130779290","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 : 2008-12-08DOI: 10.1109/PIMRC.2008.4699581
Moonseo Park, Seong-Lyun Kim
The XOR network code is widely used in the conventional network coding. However, when the channel is noisy, the XOR code is suboptimal in terms of minimizing distortion in the source signal. We propose to use a new network code for the two-way relay channel, designed to minimize signal distortion due to the channel noise. We assume the source signal X is encoded by a source encoder and the sequence of symbols is transmitted over the two-way relay channel with noise. The received sequence of symbols may be corrupted by the channel noise, and Xcirc, the estimation of X, may be different from X. We design a new network code which minimizes the distortion between X and Xcirc. To provide an algorithm to obtain a network code with minimum distortion, we define the expected distortion associated with a network code. Starting with the XOR network code, we iteratively optimize the network code to obtain smaller expected distortion, while maintaining the Latin square constraint of the network code. New network code achieves substantial performance gain over the XOR network code.
{"title":"Minimum distortion network code design for source coding over noisy channels","authors":"Moonseo Park, Seong-Lyun Kim","doi":"10.1109/PIMRC.2008.4699581","DOIUrl":"https://doi.org/10.1109/PIMRC.2008.4699581","url":null,"abstract":"The XOR network code is widely used in the conventional network coding. However, when the channel is noisy, the XOR code is suboptimal in terms of minimizing distortion in the source signal. We propose to use a new network code for the two-way relay channel, designed to minimize signal distortion due to the channel noise. We assume the source signal X is encoded by a source encoder and the sequence of symbols is transmitted over the two-way relay channel with noise. The received sequence of symbols may be corrupted by the channel noise, and Xcirc, the estimation of X, may be different from X. We design a new network code which minimizes the distortion between X and Xcirc. To provide an algorithm to obtain a network code with minimum distortion, we define the expected distortion associated with a network code. Starting with the XOR network code, we iteratively optimize the network code to obtain smaller expected distortion, while maintaining the Latin square constraint of the network code. New network code achieves substantial performance gain over the XOR network code.","PeriodicalId":125554,"journal":{"name":"2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"441 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132416234","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 : 2008-12-08DOI: 10.1109/PIMRC.2008.4699908
J. Barraca, Pedro B. Fernandes, S. Sargento, R. Rocha
The advances on wireless mesh networks are shifting the communications paradigm, where users can benefit from their cooperation to exchange information and make use of the spectrum space, forming wireless neighbourhood communities where resources are shared and services are distributed. This paper presents a modular cross-layer community management architecture, which considers that communities are formed and managed at different layers, from physical to application. It focus in more depth on one of its modules, implementing a community discovery mechanism designed to work in wireless mesh networks, and able to perform community advertisement and discovery with low overhead and delay, as compared to current approaches.
{"title":"An architecture for community mesh networking","authors":"J. Barraca, Pedro B. Fernandes, S. Sargento, R. Rocha","doi":"10.1109/PIMRC.2008.4699908","DOIUrl":"https://doi.org/10.1109/PIMRC.2008.4699908","url":null,"abstract":"The advances on wireless mesh networks are shifting the communications paradigm, where users can benefit from their cooperation to exchange information and make use of the spectrum space, forming wireless neighbourhood communities where resources are shared and services are distributed. This paper presents a modular cross-layer community management architecture, which considers that communities are formed and managed at different layers, from physical to application. It focus in more depth on one of its modules, implementing a community discovery mechanism designed to work in wireless mesh networks, and able to perform community advertisement and discovery with low overhead and delay, as compared to current approaches.","PeriodicalId":125554,"journal":{"name":"2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132038156","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 : 2008-12-08DOI: 10.1109/PIMRC.2008.4699614
P. Layec, R. Visoz, A. Berthet
Waterfilling enables a dramatic increase in capacity of multiple antenna systems, but requires perfect knowledge at transmitter.When a finite discrete rate is available, this algorithm is no more optimal since the interest lies in maximizing the sum discrete-rate. In this paper, motivated by a feedback reduction, we introduce a transceiver that partially decouples the channel into parallel subchannels. From the analogy between multi-user and single-user channels, we propose a discrete rate iterative waterfilling procedure. It first relies on the classical iterative waterfilling, and then rounds continuous rates to discrete rates with an efficient use of residual power. Simulations show that a substantial enhancement of the discrete bit loading process is provided. We further investigate the trade-off feedback-performance of different waterfilling-based systems. Simulations point out that the proposed scheme outperforms the waterfilling with nearly 60% of feedback reduction in the moderate to high SNR region, while achieving nearly 90% of the sum discrete-rate waterfilling at low SNR.
{"title":"Partial waterfilling with reduced feedback for sum discrete-rate maximization in SU-MIMO systems","authors":"P. Layec, R. Visoz, A. Berthet","doi":"10.1109/PIMRC.2008.4699614","DOIUrl":"https://doi.org/10.1109/PIMRC.2008.4699614","url":null,"abstract":"Waterfilling enables a dramatic increase in capacity of multiple antenna systems, but requires perfect knowledge at transmitter.When a finite discrete rate is available, this algorithm is no more optimal since the interest lies in maximizing the sum discrete-rate. In this paper, motivated by a feedback reduction, we introduce a transceiver that partially decouples the channel into parallel subchannels. From the analogy between multi-user and single-user channels, we propose a discrete rate iterative waterfilling procedure. It first relies on the classical iterative waterfilling, and then rounds continuous rates to discrete rates with an efficient use of residual power. Simulations show that a substantial enhancement of the discrete bit loading process is provided. We further investigate the trade-off feedback-performance of different waterfilling-based systems. Simulations point out that the proposed scheme outperforms the waterfilling with nearly 60% of feedback reduction in the moderate to high SNR region, while achieving nearly 90% of the sum discrete-rate waterfilling at low SNR.","PeriodicalId":125554,"journal":{"name":"2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131005488","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 : 2008-12-08DOI: 10.1109/PIMRC.2008.4699472
B. Banitalebi
In receivers, IQ imbalances have significant effects on the performance of data transmission. Comparison of the performance of different types of orthogonal space-time block codes (OSTBC) in the presence of IQ imbalances show that different codes donpsilat have a same behavior. Although most codes have an acceptable performance in low imbalances, they canpsilat work properly in the presence of intensive non-idealities. Despite this general similarity, there are some differences in the behavior of the codes against non-idealities. Such differences make them suitable for different situations.
{"title":"Performance comparison of different STBC codes in the presence of IQ imbalances in mobile communications","authors":"B. Banitalebi","doi":"10.1109/PIMRC.2008.4699472","DOIUrl":"https://doi.org/10.1109/PIMRC.2008.4699472","url":null,"abstract":"In receivers, IQ imbalances have significant effects on the performance of data transmission. Comparison of the performance of different types of orthogonal space-time block codes (OSTBC) in the presence of IQ imbalances show that different codes donpsilat have a same behavior. Although most codes have an acceptable performance in low imbalances, they canpsilat work properly in the presence of intensive non-idealities. Despite this general similarity, there are some differences in the behavior of the codes against non-idealities. Such differences make them suitable for different situations.","PeriodicalId":125554,"journal":{"name":"2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130483919","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 : 2008-12-08DOI: 10.1109/PIMRC.2008.4699458
François-Xavier Socheleau, S. Houcke, A. Aïssa-El-Bey, P. Ciblat
In the context of cognitive radio, system identification is a crucial step towards radio environment awareness. In this paper, we present a new OFDM system identification method based on m-sequence (MS) specific characteristics. Thanks to their good random properties, m-sequences are commonly used in existing standards (such as Wifi or WiMAX) to modulate pilot tones for channel estimation and/or for synchronization purposes. We demonstrate that such sequences show extra-properties relevant to distinguish systems from each other and therefore advocate to generalize their use in a cognitive context. MS signatures are indeed of interest since they are able to discriminate OFDM based systems that have the same modulation parameters (intercarrier spacing, cyclic prefix duration, etc.). In order to detect these signatures, we conduct a hypothesis test based on the MS high order statistics. Detailed numerical examples demonstrate the efficiency of the proposed identification criterion and especially show its benefits compared to classical correlation based methods.
{"title":"OFDM system identification based on m-sequence signatures in cognitive radio context","authors":"François-Xavier Socheleau, S. Houcke, A. Aïssa-El-Bey, P. Ciblat","doi":"10.1109/PIMRC.2008.4699458","DOIUrl":"https://doi.org/10.1109/PIMRC.2008.4699458","url":null,"abstract":"In the context of cognitive radio, system identification is a crucial step towards radio environment awareness. In this paper, we present a new OFDM system identification method based on m-sequence (MS) specific characteristics. Thanks to their good random properties, m-sequences are commonly used in existing standards (such as Wifi or WiMAX) to modulate pilot tones for channel estimation and/or for synchronization purposes. We demonstrate that such sequences show extra-properties relevant to distinguish systems from each other and therefore advocate to generalize their use in a cognitive context. MS signatures are indeed of interest since they are able to discriminate OFDM based systems that have the same modulation parameters (intercarrier spacing, cyclic prefix duration, etc.). In order to detect these signatures, we conduct a hypothesis test based on the MS high order statistics. Detailed numerical examples demonstrate the efficiency of the proposed identification criterion and especially show its benefits compared to classical correlation based methods.","PeriodicalId":125554,"journal":{"name":"2008 IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127946526","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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