Pub Date : 2011-05-03DOI: 10.1109/SARNOF.2011.5876478
F. Shayegh, M. Soleymani
In this paper we investigate the use of rateless codes by secondary users equipped with cognitive radio in a virtual unlicensed spectrum. Assuming a Poisson model for the arrival of primary users, we analyze the goodput and the throughput of secondary users. Rateless codes are used for transmitting the secondary data through parallel subchannels available in a spectrum. They can compensate for the packet loss in secondary transmission due to appearance of primary users. We calculate the overall frame error probability at the secondary receiver and use it for calculating the throughput and goodput. Numerical results indicate that LT codes as a class of rateless codes provide reliable transmissions with high throughput and small redundancy. Except for very small Poisson arrival rates, the throughput is much higher than the case without erasure coding. Therefore, in real-time multimedia transmission that retransmitting lost information packets is not possible, the use of rateless codes is very beneficial.
{"title":"Rateless codes for cognitive radio in a virtual unlicensed spectrum","authors":"F. Shayegh, M. Soleymani","doi":"10.1109/SARNOF.2011.5876478","DOIUrl":"https://doi.org/10.1109/SARNOF.2011.5876478","url":null,"abstract":"In this paper we investigate the use of rateless codes by secondary users equipped with cognitive radio in a virtual unlicensed spectrum. Assuming a Poisson model for the arrival of primary users, we analyze the goodput and the throughput of secondary users. Rateless codes are used for transmitting the secondary data through parallel subchannels available in a spectrum. They can compensate for the packet loss in secondary transmission due to appearance of primary users. We calculate the overall frame error probability at the secondary receiver and use it for calculating the throughput and goodput. Numerical results indicate that LT codes as a class of rateless codes provide reliable transmissions with high throughput and small redundancy. Except for very small Poisson arrival rates, the throughput is much higher than the case without erasure coding. Therefore, in real-time multimedia transmission that retransmitting lost information packets is not possible, the use of rateless codes is very beneficial.","PeriodicalId":339596,"journal":{"name":"34th IEEE Sarnoff Symposium","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121100015","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 : 2011-05-03DOI: 10.1109/SARNOF.2011.5876482
F. Khan, Zhouyue Pi
Almost all cellular mobile communications including first generation analog systems, second generation digital systems, third generation WCDMA, and fourth generation OFDMA systems use Ultra High Frequency (UHF) band of radio spectrum with frequencies in the range of 300MHz-3GHz. This band of spectrum is becoming increasingly crowded due to spectacular growth in mobile data and other related services. The portion of the RF spectrum above 3GHz has largely been uxexploited for commercial mobile applications. In this paper, we reason why wireless community should start looking at 3–300GHz spectrum for mobile broadband applications. We discuss propagation and device technology challenges associated with this band as well as its unique advantages such as spectrum availability and small component sizes for mobile applications.
{"title":"mmWave mobile broadband (MMB): Unleashing the 3–300GHz spectrum","authors":"F. Khan, Zhouyue Pi","doi":"10.1109/SARNOF.2011.5876482","DOIUrl":"https://doi.org/10.1109/SARNOF.2011.5876482","url":null,"abstract":"Almost all cellular mobile communications including first generation analog systems, second generation digital systems, third generation WCDMA, and fourth generation OFDMA systems use Ultra High Frequency (UHF) band of radio spectrum with frequencies in the range of 300MHz-3GHz. This band of spectrum is becoming increasingly crowded due to spectacular growth in mobile data and other related services. The portion of the RF spectrum above 3GHz has largely been uxexploited for commercial mobile applications. In this paper, we reason why wireless community should start looking at 3–300GHz spectrum for mobile broadband applications. We discuss propagation and device technology challenges associated with this band as well as its unique advantages such as spectrum availability and small component sizes for mobile applications.","PeriodicalId":339596,"journal":{"name":"34th IEEE Sarnoff Symposium","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114336856","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 : 2011-05-03DOI: 10.1109/SARNOF.2011.5876470
M. Grieger, Peter Helbing, G. Fettweis, P. Marsch
Coordinated multi-point (CoMP) in the cellular uplink, offering large improvements in spectral efficiency and fairness, appears to be an effective option to combat inter-cell interference. Current approaches range from coordinated scheduling to coherent joint detection. A major drawback of coherent joint detection is the large extent of additional backhaul infrastructure required for the exchange of received signals among base stations. Theoretical research on this topic emphasizes the benefits of source coding as a method to reduce the backhaul that is required. This paper complements previous publications through field trial results obtained in a representative urban setup. Different scalar and vector compression algorithms are compared in terms of their complexity as well as the average distortion of the compressed signal. System performance, evaluated in terms of the SINR of the equalized transmit signals, was determined for measurement data to investigate performance of compression algorithms under real-world conditions.
{"title":"Field trial evaluation of compression algorithms for distributed antenna systems","authors":"M. Grieger, Peter Helbing, G. Fettweis, P. Marsch","doi":"10.1109/SARNOF.2011.5876470","DOIUrl":"https://doi.org/10.1109/SARNOF.2011.5876470","url":null,"abstract":"Coordinated multi-point (CoMP) in the cellular uplink, offering large improvements in spectral efficiency and fairness, appears to be an effective option to combat inter-cell interference. Current approaches range from coordinated scheduling to coherent joint detection. A major drawback of coherent joint detection is the large extent of additional backhaul infrastructure required for the exchange of received signals among base stations. Theoretical research on this topic emphasizes the benefits of source coding as a method to reduce the backhaul that is required. This paper complements previous publications through field trial results obtained in a representative urban setup. Different scalar and vector compression algorithms are compared in terms of their complexity as well as the average distortion of the compressed signal. System performance, evaluated in terms of the SINR of the equalized transmit signals, was determined for measurement data to investigate performance of compression algorithms under real-world conditions.","PeriodicalId":339596,"journal":{"name":"34th IEEE Sarnoff Symposium","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129574545","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 : 2011-05-03DOI: 10.1109/SARNOF.2011.5876455
A. Reddy
A typical MIMO system utilizes multiple antennas to transmit simultaneously several independent data streams to the receiver end. As a result of this inter-stream interference is said to occur since the reception of each stream at the receiver will be disturbed not only by noise but from the interference of other streams as well. In order to successfully detect and decode the received signal, joint detection and decoding can be employed to separate and recover the transmitted data in the best possible manner. This approach has huge complexity which grows exponentially as the number of antennas increases, thus prohibiting its implementation in a real time system. For real time implementation computationally effective methods are sought after but which often does not necessarily yield the best performance thus incurring a performance-complexity trade-off. The current research in this area has led to the development of both linear and non-linear techniques most of which are computationally intensive and complex. This paper discusses low complexity methods which are suitable for real time applications.
{"title":"Efficient decoding methods in MIMO systems","authors":"A. Reddy","doi":"10.1109/SARNOF.2011.5876455","DOIUrl":"https://doi.org/10.1109/SARNOF.2011.5876455","url":null,"abstract":"A typical MIMO system utilizes multiple antennas to transmit simultaneously several independent data streams to the receiver end. As a result of this inter-stream interference is said to occur since the reception of each stream at the receiver will be disturbed not only by noise but from the interference of other streams as well. In order to successfully detect and decode the received signal, joint detection and decoding can be employed to separate and recover the transmitted data in the best possible manner. This approach has huge complexity which grows exponentially as the number of antennas increases, thus prohibiting its implementation in a real time system. For real time implementation computationally effective methods are sought after but which often does not necessarily yield the best performance thus incurring a performance-complexity trade-off. The current research in this area has led to the development of both linear and non-linear techniques most of which are computationally intensive and complex. This paper discusses low complexity methods which are suitable for real time applications.","PeriodicalId":339596,"journal":{"name":"34th IEEE Sarnoff Symposium","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117216378","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 : 2011-05-03DOI: 10.1109/SARNOF.2011.5876443
V. Rodriguez
It has long been recognised that a wireless communication system can be more efficient if link-layer parameters such as modulation order, symbol rate and packet size, are (adaptively) optimised. A common optimising criterion is to maximise spectral efficiency (bits per second per Hertz (bps/Hertz)) subject to a very low bit-error constraint. But a packet-oriented criterion for link adaptation seems more appropriate for practical communication networks fitted with strong error detection and a selective packet re-transmission mechanism. In recent work, we performed link optimisation for maximal bits per second or bits per Joule for data (delay-tolerant) traffic. In the present work, we extend our previous analysis to consider the case of costly power. The cost can be interpreted in the common economic sense, or can be a signal to encourage efficient resource use in a decentralised matter; furthermore, it may simply be a “Lagrange multiplier” in a centralised optimisation. When the symbol rate is flexible, the result under pricing is similar to the costless scenario: a set of possible link configurations can be ranked by the slope of a tangent line from the origin to the graph of a scaled version of the PSRF: the steeper the tangent the better the configuration. However, if the “effective price” — the power price divided by the noise-normalised channel gain — is sufficiently high, it is optimal for the terminal not to operate. If the symbol rate is fixed, the optimal configuration depends on the effective price.
{"title":"Generalised link-layer adaptation with costly power under higher-layer criteria","authors":"V. Rodriguez","doi":"10.1109/SARNOF.2011.5876443","DOIUrl":"https://doi.org/10.1109/SARNOF.2011.5876443","url":null,"abstract":"It has long been recognised that a wireless communication system can be more efficient if link-layer parameters such as modulation order, symbol rate and packet size, are (adaptively) optimised. A common optimising criterion is to maximise spectral efficiency (bits per second per Hertz (bps/Hertz)) subject to a very low bit-error constraint. But a packet-oriented criterion for link adaptation seems more appropriate for practical communication networks fitted with strong error detection and a selective packet re-transmission mechanism. In recent work, we performed link optimisation for maximal bits per second or bits per Joule for data (delay-tolerant) traffic. In the present work, we extend our previous analysis to consider the case of costly power. The cost can be interpreted in the common economic sense, or can be a signal to encourage efficient resource use in a decentralised matter; furthermore, it may simply be a “Lagrange multiplier” in a centralised optimisation. When the symbol rate is flexible, the result under pricing is similar to the costless scenario: a set of possible link configurations can be ranked by the slope of a tangent line from the origin to the graph of a scaled version of the PSRF: the steeper the tangent the better the configuration. However, if the “effective price” — the power price divided by the noise-normalised channel gain — is sufficiently high, it is optimal for the terminal not to operate. If the symbol rate is fixed, the optimal configuration depends on the effective price.","PeriodicalId":339596,"journal":{"name":"34th IEEE Sarnoff Symposium","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122642932","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 : 2011-05-03DOI: 10.1109/SARNOF.2011.5876484
Eun Kyung Lee, John Paul Varkey, D. Pompili
In Wireless Sensor Networks (WSNs), sensing nodes operate in dynamic environments resulting in neighboring nodes being discovered or lost at any moment causing the network topology to change constantly. Hence, routing schemes especially geographical ones (which use node positions to route data packets) require periodic exchange of control packets to discover neighboring nodes. Even though it is intuitive that the overhead caused by their periodic broadcasts may affect the end-to-end performance of the routing scheme, previous works have not thoroughly studied the impact of transmission power and frequency of control packets in static as well as mobile environments. Hence, based on our study, Distributed Neighborhood Discovery Protocol (DNDP) is proposed that can make online decisions to find the best transmit power and frequency for sending discovery packets so to minimize the effect on routing.
{"title":"On the impact of neighborhood discovery on geographical routing in wireless sensor networks","authors":"Eun Kyung Lee, John Paul Varkey, D. Pompili","doi":"10.1109/SARNOF.2011.5876484","DOIUrl":"https://doi.org/10.1109/SARNOF.2011.5876484","url":null,"abstract":"In Wireless Sensor Networks (WSNs), sensing nodes operate in dynamic environments resulting in neighboring nodes being discovered or lost at any moment causing the network topology to change constantly. Hence, routing schemes especially geographical ones (which use node positions to route data packets) require periodic exchange of control packets to discover neighboring nodes. Even though it is intuitive that the overhead caused by their periodic broadcasts may affect the end-to-end performance of the routing scheme, previous works have not thoroughly studied the impact of transmission power and frequency of control packets in static as well as mobile environments. Hence, based on our study, Distributed Neighborhood Discovery Protocol (DNDP) is proposed that can make online decisions to find the best transmit power and frequency for sending discovery packets so to minimize the effect on routing.","PeriodicalId":339596,"journal":{"name":"34th IEEE Sarnoff Symposium","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125478600","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 : 2011-05-03DOI: 10.1109/SARNOF.2011.5876459
I. Lu, Kun-Ju Tsai
Based on differential properties of the received preamble, a novel start of packet (SoP) detection and synchronization approach is developed for the IEEE802.11n MIMO-OFDM WLAN system to obtain better mean and variance of timing estimates and lower missing packet and false alarm rates.
{"title":"A novel start-of-packet detection and synchronization scheme","authors":"I. Lu, Kun-Ju Tsai","doi":"10.1109/SARNOF.2011.5876459","DOIUrl":"https://doi.org/10.1109/SARNOF.2011.5876459","url":null,"abstract":"Based on differential properties of the received preamble, a novel start of packet (SoP) detection and synchronization approach is developed for the IEEE802.11n MIMO-OFDM WLAN system to obtain better mean and variance of timing estimates and lower missing packet and false alarm rates.","PeriodicalId":339596,"journal":{"name":"34th IEEE Sarnoff Symposium","volume":"5 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127087589","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 : 2011-05-03DOI: 10.1109/SARNOF.2011.5876435
M. Karol
Exploiting the broadcast nature of wireless channels, transmitted packets “skip ahead” to receiving nodes farther downstream along an existing, established mesh routing path. Packets are thereby able to more quickly advance through a mesh network towards their destination. This occurs on a packet-by-packet basis and is advantageous even if the underlying path (at that moment) has been optimized. Analysis demonstrates improvements of 25% and greater (as a function of key network parameters), which translates into lower end-to-end latency and possibly higher network throughput.
{"title":"Skip-ahead routing in wireless networks","authors":"M. Karol","doi":"10.1109/SARNOF.2011.5876435","DOIUrl":"https://doi.org/10.1109/SARNOF.2011.5876435","url":null,"abstract":"Exploiting the broadcast nature of wireless channels, transmitted packets “skip ahead” to receiving nodes farther downstream along an existing, established mesh routing path. Packets are thereby able to more quickly advance through a mesh network towards their destination. This occurs on a packet-by-packet basis and is advantageous even if the underlying path (at that moment) has been optimized. Analysis demonstrates improvements of 25% and greater (as a function of key network parameters), which translates into lower end-to-end latency and possibly higher network throughput.","PeriodicalId":339596,"journal":{"name":"34th IEEE Sarnoff Symposium","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130986369","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 : 2011-05-03DOI: 10.1109/SARNOF.2011.5876477
E. Lu, I. Lu
Coordinated Beamforming (CBF) has been studied in hope of mitigating the inter-cell interference experienced by cell-edge users. Unfortunately, due to the limitations and/or impracticalities of the proposed designs, the expected performance gains have yet to be realized. In this work, a decentralized framework (and various example designs) is proposed for the practical transceiver and signaling design of a K-pair system desiring to employ CBF. Relying on channel soundings from the users and equivalent channel soundings from the cell sites (all on the same frequency), the optimum performance of centralized interference alignment designs is achieved (if not surpassed) when each pair's number of data streams is equal to its user's number of antennas. In addition, higher sum capacities than the generalized iterative approach, a centralized MMSE CBF design, are numerically observed. Clearly, practical CBF designs which can deliver the expected performance gains are finally available.
{"title":"Practical decentralized high-performance coordinated beamforming","authors":"E. Lu, I. Lu","doi":"10.1109/SARNOF.2011.5876477","DOIUrl":"https://doi.org/10.1109/SARNOF.2011.5876477","url":null,"abstract":"Coordinated Beamforming (CBF) has been studied in hope of mitigating the inter-cell interference experienced by cell-edge users. Unfortunately, due to the limitations and/or impracticalities of the proposed designs, the expected performance gains have yet to be realized. In this work, a decentralized framework (and various example designs) is proposed for the practical transceiver and signaling design of a K-pair system desiring to employ CBF. Relying on channel soundings from the users and equivalent channel soundings from the cell sites (all on the same frequency), the optimum performance of centralized interference alignment designs is achieved (if not surpassed) when each pair's number of data streams is equal to its user's number of antennas. In addition, higher sum capacities than the generalized iterative approach, a centralized MMSE CBF design, are numerically observed. Clearly, practical CBF designs which can deliver the expected performance gains are finally available.","PeriodicalId":339596,"journal":{"name":"34th IEEE Sarnoff Symposium","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127063771","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 : 2011-05-03DOI: 10.1109/SARNOF.2011.5876467
Dandan Wang, R. Soni, Pichun Chen, A. Rao
More and more video application are being carried on wireless systems with the development of the smart phones. However, the performance of these applications is lack of study, especially for the most advanced LTE networks. In this paper, we investigate the performance of the video telephony over the LTE downlink systems with and without QoS provisioning. The simulation results using two classical algorithms: proportional fair scheduler (PF) and proportional fair scheduler with minimum/maximum rate constraints (PFMR) are presented. Both pure video telephony traffic scenario and two-service scenario of mixed video with full buffer traffics are considered in this paper. The simulation results show that the video capacity is mainly limited by the delay of the video users and the video capacity is increased using PFMR compared with PF, which shows the benefit of providing QoS provisioning. The paper also shows the delay and throughput is highly related to the geometry of the users. The worse the user's geometry is, the user experiences the longer delay and achieves the smaller throughput.
{"title":"Video telephony over downlink LTE systems with/without QoS provisioning","authors":"Dandan Wang, R. Soni, Pichun Chen, A. Rao","doi":"10.1109/SARNOF.2011.5876467","DOIUrl":"https://doi.org/10.1109/SARNOF.2011.5876467","url":null,"abstract":"More and more video application are being carried on wireless systems with the development of the smart phones. However, the performance of these applications is lack of study, especially for the most advanced LTE networks. In this paper, we investigate the performance of the video telephony over the LTE downlink systems with and without QoS provisioning. The simulation results using two classical algorithms: proportional fair scheduler (PF) and proportional fair scheduler with minimum/maximum rate constraints (PFMR) are presented. Both pure video telephony traffic scenario and two-service scenario of mixed video with full buffer traffics are considered in this paper. The simulation results show that the video capacity is mainly limited by the delay of the video users and the video capacity is increased using PFMR compared with PF, which shows the benefit of providing QoS provisioning. The paper also shows the delay and throughput is highly related to the geometry of the users. The worse the user's geometry is, the user experiences the longer delay and achieves the smaller throughput.","PeriodicalId":339596,"journal":{"name":"34th IEEE Sarnoff Symposium","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127597768","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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