Pub Date : 2008-12-30DOI: 10.1109/ISWCS.2008.4726119
J. Cortés, J. Dunlop, F. Kolberg
This paper addresses the trend in wireless sensor network applications of increasing node density and multi-hop communications that result into extremely challenging design constraints. SSAS, an adaptive hybrid localised sink-oriented Routing/MAC protocol is proposed. It offers a self-configuration scalable solution for large random sensor networks and attempts to alleviate multi-hop congestion problems. The strength of the SSAS protocol is based on the scheduled access at the sinks and the enhancement of the number of one-hop sinks' neighbours by profiting directional antenna capabilities. By means of modelling off-the-shelf sensor node architecture with realistic radio channel assumptions and the use of network simulations, this paper shows significant improvements of SSAS (such as 10 times higher network lifetime) compared to other techniques such as pure contention-based alternative (C-MAC), B-MAC and LEACH.
{"title":"Adaptive MAC with scheduled sectorial access at sinks (SSAS) in Wireless Sensor Networks","authors":"J. Cortés, J. Dunlop, F. Kolberg","doi":"10.1109/ISWCS.2008.4726119","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726119","url":null,"abstract":"This paper addresses the trend in wireless sensor network applications of increasing node density and multi-hop communications that result into extremely challenging design constraints. SSAS, an adaptive hybrid localised sink-oriented Routing/MAC protocol is proposed. It offers a self-configuration scalable solution for large random sensor networks and attempts to alleviate multi-hop congestion problems. The strength of the SSAS protocol is based on the scheduled access at the sinks and the enhancement of the number of one-hop sinks' neighbours by profiting directional antenna capabilities. By means of modelling off-the-shelf sensor node architecture with realistic radio channel assumptions and the use of network simulations, this paper shows significant improvements of SSAS (such as 10 times higher network lifetime) compared to other techniques such as pure contention-based alternative (C-MAC), B-MAC and LEACH.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"174 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115526462","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726007
Ayman Khalil, A. Stephan, M. Crussiére, J. Hélard
In this paper, we investigate a cross-layer design for the packet scheduling and the resource allocation in UWB systems. This design considers the combination of queuing and channel state information (CSI) which provides QoS support for multimedia applications in UWB. For the physical layer, the use of a linear precoded orthogonal division multiplexing (LP-OFDM) waveform is proposed because of its significant performance increase compared to the WiMedia proposal. For the medium access control layer, scheduling is performed in order to differentiate between the different users and to satisfy their quality of service constraints. This cross-layer approach optimizes the system spectral efficiency and solves the problem in the WiMedia solution of cohabitation of more than three users sharing the three sub-bands of the same channel. Simulation results show that the proposed scheme leads to a considerable improvement in resource allocation and can guarantee the required quality of service.
{"title":"Multi-user cross-layer allocation design for LP-OFDM high data rate UWB systems","authors":"Ayman Khalil, A. Stephan, M. Crussiére, J. Hélard","doi":"10.1109/ISWCS.2008.4726007","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726007","url":null,"abstract":"In this paper, we investigate a cross-layer design for the packet scheduling and the resource allocation in UWB systems. This design considers the combination of queuing and channel state information (CSI) which provides QoS support for multimedia applications in UWB. For the physical layer, the use of a linear precoded orthogonal division multiplexing (LP-OFDM) waveform is proposed because of its significant performance increase compared to the WiMedia proposal. For the medium access control layer, scheduling is performed in order to differentiate between the different users and to satisfy their quality of service constraints. This cross-layer approach optimizes the system spectral efficiency and solves the problem in the WiMedia solution of cohabitation of more than three users sharing the three sub-bands of the same channel. Simulation results show that the proposed scheme leads to a considerable improvement in resource allocation and can guarantee the required quality of service.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126838664","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726100
Stephan Stiglmayr, Johannes Georg Klotz, M. Bossert
In this paper we present the mutual information of a bit-interleaved V-BLAST space-time architecture. We assume interference cancellation by successive detection using MMSE equalizers without decoding of the channel codes. The mutual information is dependent on the MIMO channel realization and the detection order. However, the mutual information is very similar to that of an AWGN channel when plotted over the SINR per stream. The mutual information can be used for developing adaptive modulation and coding methods for V-BLAST.
{"title":"Mutual information of V-BLAST transmission","authors":"Stephan Stiglmayr, Johannes Georg Klotz, M. Bossert","doi":"10.1109/ISWCS.2008.4726100","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726100","url":null,"abstract":"In this paper we present the mutual information of a bit-interleaved V-BLAST space-time architecture. We assume interference cancellation by successive detection using MMSE equalizers without decoding of the channel codes. The mutual information is dependent on the MIMO channel realization and the detection order. However, the mutual information is very similar to that of an AWGN channel when plotted over the SINR per stream. The mutual information can be used for developing adaptive modulation and coding methods for V-BLAST.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127131301","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726065
T. Fujita, D. Uchida, Y. Fujino, Kazuji Watanabe
This paper presents a slot timing detection method with multiple-symbol differential detection (MSDD) that offers improved transmission efficiency and mitigates the performance deterioration caused by carrier frequency offset. The method is applicable for burst wireless systems with short burst M-differential phase shift keying (MDPSK) signals and low symbol rates, which suits radio-frequency identifications (RF-IDs) or other ubiquitous wireless applications. Computer simulations show that the proposed method improves slot timing detection and error rate performances and yields robust demodulation of data symbols against carrier frequency offset.
{"title":"A slot timing detection method with multiple-symbol differential detection for MDPSK burst signals","authors":"T. Fujita, D. Uchida, Y. Fujino, Kazuji Watanabe","doi":"10.1109/ISWCS.2008.4726065","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726065","url":null,"abstract":"This paper presents a slot timing detection method with multiple-symbol differential detection (MSDD) that offers improved transmission efficiency and mitigates the performance deterioration caused by carrier frequency offset. The method is applicable for burst wireless systems with short burst M-differential phase shift keying (MDPSK) signals and low symbol rates, which suits radio-frequency identifications (RF-IDs) or other ubiquitous wireless applications. Computer simulations show that the proposed method improves slot timing detection and error rate performances and yields robust demodulation of data symbols against carrier frequency offset.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121883169","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726123
L. Stabellini
Neighbor discovery is a fundamental procedure that needs to be carried out in every wireless sensor network in order to enable communication capabilities. If nodes are mobile or multiple channels are used in the network, the same algorithm may be needed to be carried out several times during the network lifetime, consuming precious energy. In this paper we propose a way for optimizing a neighbor discovery procedure suitable for a single-radio single-channel scenario. Assuming a realistic energy model which accounts for energy required for transmitting discovery queries and listening for acknowledgements and explicitly accounting for collisions we exploit power control and the use of a contention window of variable size to minimize sensors¿ energy consumption while both transmitting and receiving. We formulate the neighbor discovery problem as a Markov decision process and through dynamic programming we compute an optimal policy defining the power level and the contention window size that must be used while broadcasting queries. This policy minimizes the energy cost of the discovery procedure for a given constraint on the maximum probability of having collisions. We further provide guidelines useful for implementing sub-optimal policies which perform asymptotically optimal for high node densities and can be computed on-line by motes with low capabilities.
{"title":"Energy optimal neighbor discovery for single-radio single-channel wireless sensor networks","authors":"L. Stabellini","doi":"10.1109/ISWCS.2008.4726123","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726123","url":null,"abstract":"Neighbor discovery is a fundamental procedure that needs to be carried out in every wireless sensor network in order to enable communication capabilities. If nodes are mobile or multiple channels are used in the network, the same algorithm may be needed to be carried out several times during the network lifetime, consuming precious energy. In this paper we propose a way for optimizing a neighbor discovery procedure suitable for a single-radio single-channel scenario. Assuming a realistic energy model which accounts for energy required for transmitting discovery queries and listening for acknowledgements and explicitly accounting for collisions we exploit power control and the use of a contention window of variable size to minimize sensors¿ energy consumption while both transmitting and receiving. We formulate the neighbor discovery problem as a Markov decision process and through dynamic programming we compute an optimal policy defining the power level and the contention window size that must be used while broadcasting queries. This policy minimizes the energy cost of the discovery procedure for a given constraint on the maximum probability of having collisions. We further provide guidelines useful for implementing sub-optimal policies which perform asymptotically optimal for high node densities and can be computed on-line by motes with low capabilities.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123588830","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726050
Omar S. Salih, Chengxiang Wang, D. Laurenson
Generative models hold the promise of reducing the computational load and cost caused by directly simulating a real system. They are vital to the design and performance evaluation of error control schemes and high layer wireless communication protocols. Therefore, designing an efficient and accurate generative model is highly desirable. Moreover, the errors encountered in digital wireless channels exhibit correlation among them. This stimulates us to construct a Markovian based generative model with two embedded processes. The first process is dedicated to assembling error bursts with error-free bursts, whereas the second one is devoted to creating individual error bursts employing the maximum gap norm within error bursts. This premise is utilized in this paper to show that the resulting generative model can generate error sequences with desired bit correlations and is capable of statistically matching a descriptive model, derived from an enhanced general packet radio service (EGPRS) transmission system, regardless of the configuration of its error sequences.
{"title":"Double embedded processes based hidden Markov models for binary digital wireless channels","authors":"Omar S. Salih, Chengxiang Wang, D. Laurenson","doi":"10.1109/ISWCS.2008.4726050","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726050","url":null,"abstract":"Generative models hold the promise of reducing the computational load and cost caused by directly simulating a real system. They are vital to the design and performance evaluation of error control schemes and high layer wireless communication protocols. Therefore, designing an efficient and accurate generative model is highly desirable. Moreover, the errors encountered in digital wireless channels exhibit correlation among them. This stimulates us to construct a Markovian based generative model with two embedded processes. The first process is dedicated to assembling error bursts with error-free bursts, whereas the second one is devoted to creating individual error bursts employing the maximum gap norm within error bursts. This premise is utilized in this paper to show that the resulting generative model can generate error sequences with desired bit correlations and is capable of statistically matching a descriptive model, derived from an enhanced general packet radio service (EGPRS) transmission system, regardless of the configuration of its error sequences.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125652638","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726012
Teresa Araujo, R. Dinis
In this paper we consider the evaluation of nonlinear distortion effects on the downlink transmission of systems employing OFDMA (orthogonal frequency division multiple access) signals. Our results allow an analytical spectral characterization of the transmitted signals, as well as the computation of nonlinear interference levels on the received signals. It is shown that the set of subcarriers allocated to each user and the corresponding power have a key impact on the nonlinear distortion effects. It is also shown that nonlinear distortion levels are lower when just a small fraction of the subcarriers is used (i.e., when the system load is small).
{"title":"Analytical evaluation of nonlinear distortion effects on OFDMA signals used in the downlink transmission","authors":"Teresa Araujo, R. Dinis","doi":"10.1109/ISWCS.2008.4726012","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726012","url":null,"abstract":"In this paper we consider the evaluation of nonlinear distortion effects on the downlink transmission of systems employing OFDMA (orthogonal frequency division multiple access) signals. Our results allow an analytical spectral characterization of the transmitted signals, as well as the computation of nonlinear interference levels on the received signals. It is shown that the set of subcarriers allocated to each user and the corresponding power have a key impact on the nonlinear distortion effects. It is also shown that nonlinear distortion levels are lower when just a small fraction of the subcarriers is used (i.e., when the system load is small).","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131728291","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726060
Priyanka Rawat, J. Bonnin, L. Toutain
The IP tunneling mechanisms have important applications in network solutions and are widely used in numerous contexts such as security (VPN), IPv4 to IPv6 transition, and mobility support (MobileIP and NEMO). However, these tunneling mechanisms induce a large overhead resulting from adding several protocol headers in each packet. Moreover, this header overhead could be found on wireless links which have scarce resources by nature. Header compression methods are often used on connection oriented communication (e.g., UMTS networks) to reduce overhead on the wireless part. In this paper we describe our work toward a novel tunneling header compression protocol, TuCP (tunneling compression protocol), that could be used over IP tunneling mechanisms. It can compress headers of various tunneling protocols such as UDP, PPP, L2TP, GRE etc. TuCP provides a solution for the reordering problem (in tunneling) and thus it extends the usage of header compression mechanisms such as ROHC from point to point links to the IP tunnels passing over the Internet. We present the design and a preliminary implementation of TuCP. Further, we give an evaluation of header overhead reduction and compression efficiency achieved by the protocol.
{"title":"Designing a tunneling header compression (TuCP) for tunneling over IP","authors":"Priyanka Rawat, J. Bonnin, L. Toutain","doi":"10.1109/ISWCS.2008.4726060","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726060","url":null,"abstract":"The IP tunneling mechanisms have important applications in network solutions and are widely used in numerous contexts such as security (VPN), IPv4 to IPv6 transition, and mobility support (MobileIP and NEMO). However, these tunneling mechanisms induce a large overhead resulting from adding several protocol headers in each packet. Moreover, this header overhead could be found on wireless links which have scarce resources by nature. Header compression methods are often used on connection oriented communication (e.g., UMTS networks) to reduce overhead on the wireless part. In this paper we describe our work toward a novel tunneling header compression protocol, TuCP (tunneling compression protocol), that could be used over IP tunneling mechanisms. It can compress headers of various tunneling protocols such as UDP, PPP, L2TP, GRE etc. TuCP provides a solution for the reordering problem (in tunneling) and thus it extends the usage of header compression mechanisms such as ROHC from point to point links to the IP tunnels passing over the Internet. We present the design and a preliminary implementation of TuCP. Further, we give an evaluation of header overhead reduction and compression efficiency achieved by the protocol.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121465584","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726078
P. Weitkemper, D. Wübben, K. Kammeyer
In this paper, a new combination of a multiple access scheme and spatial diversity offered by relays is proposed. In order to support several users in a system, interleave division multiple access (IDMA) is suggested here due to the capability to deal with asynchronous transmission by the users. The relays apply amplify-and-forward combined with delay-diversity in order to exploit the spatial diversity without the need of synchronization of the relays. Furthermore, the IDMA detector can easily be extended to utilize the diversity very efficiently. So this combination of basic approaches can deal with asynchronous transmission of the users and the relays, respectively, resulting in a very flexible system with small signaling overhead.
{"title":"Delay-diversity in multi-user relay systems with Interleave Division Multiple Access","authors":"P. Weitkemper, D. Wübben, K. Kammeyer","doi":"10.1109/ISWCS.2008.4726078","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726078","url":null,"abstract":"In this paper, a new combination of a multiple access scheme and spatial diversity offered by relays is proposed. In order to support several users in a system, interleave division multiple access (IDMA) is suggested here due to the capability to deal with asynchronous transmission by the users. The relays apply amplify-and-forward combined with delay-diversity in order to exploit the spatial diversity without the need of synchronization of the relays. Furthermore, the IDMA detector can easily be extended to utilize the diversity very efficiently. So this combination of basic approaches can deal with asynchronous transmission of the users and the relays, respectively, resulting in a very flexible system with small signaling overhead.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115078775","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726046
F. Bellili, A. Stephenne, S. Affes
We propose a new technique to estimate the signal-to-noise ratio (SNR) over flat fading time-varying single-input multiple-output (SIMO) channels, for quadrature amplitude modulation (QAM) signals in complex additive white Gaussian noise (AWGN). This technique relies on the use of periodically transmitted pilot symbols in the estimation process. It is a decision directed (DD) procedure since detected data symbols are also used. Performance is assessed via Monte Carlo simulations. Using the normalized root mean square error (NRMSE) as a measure of performance, our new estimator performs well over a wide SNR range.
{"title":"SNR estimation of QAM-modulated transmissions over time-varying SIMO channels","authors":"F. Bellili, A. Stephenne, S. Affes","doi":"10.1109/ISWCS.2008.4726046","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726046","url":null,"abstract":"We propose a new technique to estimate the signal-to-noise ratio (SNR) over flat fading time-varying single-input multiple-output (SIMO) channels, for quadrature amplitude modulation (QAM) signals in complex additive white Gaussian noise (AWGN). This technique relies on the use of periodically transmitted pilot symbols in the estimation process. It is a decision directed (DD) procedure since detected data symbols are also used. Performance is assessed via Monte Carlo simulations. Using the normalized root mean square error (NRMSE) as a measure of performance, our new estimator performs well over a wide SNR range.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129922897","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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