In this paper,we investigate the system performance of a heterogeneous cellular network consisting of a macro cell and a small cell,where each cell has one user and one base station with multiple antennas.The macro ba...In this paper,we investigate the system performance of a heterogeneous cellular network consisting of a macro cell and a small cell,where each cell has one user and one base station with multiple antennas.The macro base station(MBS)and the small base station(SBS)transmit their confidential messages to the macro user(MU)and the small user(SU)over their shared spectrum respectively.To enhance the system sum rate(SSR)of MBS-MU and SBS-SU transmission,we propose joint antenna selection combined with optimal power allocation(JAS-OPA)scheme and independent antenna selection combined with optimal power allocation(IAS-OPA)scheme.The JAS-OPA scheme requires to know the channel state information(CSI)of transmission channels and interference channels,while the IAS-OPA scheme only needs to know the CSI of transmission channels.In addition,we carry out the analysis for conventional round-robin antenna selection combined with optimal power allocation(RR-OPA)as a benchmark scheme.We formulate the SSR maximization problem through the power allocation between MBS and SBS and propose iterative OPA algorithms for JAS-OPA,IAS-OPA and RR-OPA schemes,respectively.The results show that the OPA schemes outperform the equal power allocation in terms of SSR.Moreover,we provide the closed-form expression of the system outage probability(SOP)for IAS scheme and RR scheme,it shows the SOP performance can be significantly improved by our proposed IAS scheme compared with RR scheme.展开更多
The fifth generation （5G） wireless communication is currently a hot research topic and wireless communication systems on high speed railways （HSR） are important applications of 5G technologies. Existing stud- ies ...The fifth generation （5G） wireless communication is currently a hot research topic and wireless communication systems on high speed railways （HSR） are important applications of 5G technologies. Existing stud- ies about 5G wireless systems on high speed railways （HSR） often utilize ideal channel parameters and are usually based on simple scenarios. In this paper, we evaluate the down- link throughput of 5G HSR communication systems on three typical scenarios including urban, cutting and viaduct with three different channel estimators. The channel parameters of each scenario are generated with tapped delay line （TDL） models through ray-tracing sim- ulations, which can be considered as a good match to practical situations. The channel estimators including least square （LS）, linear minimum mean square error （LMMSE）, and our proposed historical information based ba- sis expansion model （HiBEM）. We analyze the performance of the HiBEM estimator in terms of mean square error （MSE） and evaluate the system throughputs with different channel estimates over each scenario. Simulation results are then provided to corroborate our proposed studies. It is shown that our HiBEM estimator outperforms other estimators and that the sys-tem throughput can reach the highest point in the viaduct scenario.展开更多
In this paper, we consider a multi-relay cooperative communication network that consists of a source node transmitting to its destination with the help of multiple decode-and- forward (DF) relays. Specifically, the DF...In this paper, we consider a multi-relay cooperative communication network that consists of a source node transmitting to its destination with the help of multiple decode-and- forward (DF) relays. Specifically, the DF relays that succeed in decoding the source signal are allowed to re-transmit their decoded results simultaneously to the destination in a cooperative beamforming manner. In order to carry out the cooperative beamforming, the destination needs to send the quantized channel state information (CSI) to the relays through a limited feedback channel in the face of channel quantization errors (CQE). We propose a CQE oriented multi-relay beamforming (MRB) scheme, denoted CQE-MRB for short, for the sake of improving the throughput of relay-destination transmissions. An effective throughput defined as the difference between the transmission rate and the feedback rate is used to measure an outage probability of the source-destination transmission. Simulation results demonstrate that the outage performance of proposed CQEMRB scheme is improved substantially with an increasing number of relays. Moreover, it is shown that the number of channel quantization bits can be further optimized to minimize the outage probability of proposed CQE-MRB scheme.展开更多
The ever increasing wireless data services, such asimaging, video, audio, multimedia, etc., have de-mands for the very high speed wireless communicationsand network, which are unfortunately a bottleneck whencombining ...The ever increasing wireless data services, such asimaging, video, audio, multimedia, etc., have de-mands for the very high speed wireless communicationsand network, which are unfortunately a bottleneck whencombining with the wireline core network. Users＇ arenow expecting high quality of experience with low-costdevices, ubiquitous connectivity, energy efficiency, highreliability, or even ultra-low latency if a vehicle terminalis applied.展开更多
With the massive increase of wirelessly connected devices and the rapid development of the Internet, information is transmitted more and more frequently. Since the information transmissions over these networks are gre...With the massive increase of wirelessly connected devices and the rapid development of the Internet, information is transmitted more and more frequently. Since the information transmissions over these networks are greatly threatened not only by the imperfection of channels but also by the potential attackers or eavesdroppers, security and reliability become some of the crucial requirements for our future networks. Due to the complex dynamic behavior, ergodicity, wide spectrum and sensitivity to initial values, chaos signals show most required attributes of good cryptosystems and great potentials in optical fiber communications for desirable spatial accuracy and distance. In this context, it has become imperative to investigate and apply chaos theories to solve emerging secure communication problems in various networks. This includes leveraging chaos systems and signals to address a wide range of secure communication challenges in optical fiber communications, chaos cipher, image encryption, etc.展开更多
Tooth is a complex hard tissue organ and consists of multiple cell types that are regulated by important signaling pathways such as Wnt and BMP signaling.Serious injuries and/or loss of tooth or periodontal tissues ma...Tooth is a complex hard tissue organ and consists of multiple cell types that are regulated by important signaling pathways such as Wnt and BMP signaling.Serious injuries and/or loss of tooth or periodontal tissues may significantly impact aesthetic appearance,essential oral functions and the quality of life.Regenerative dentistry holds great promise in treating oral/dental disorders.The past decade has witnessed a rapid expansion of our understanding of the biological features of dental stem cells,along with the signaling mechanisms governing stem cell self-renewal and differentiation.In this review,we first summarize the biological characteristics of seven types of dental stem cells,including dental pulp stem cells,stem cells from apical papilla,stem cells from human exfoliated deciduous teeth,dental follicle precursor cells,periodontal ligament stem cells,alveolar bone-derived mesenchymal stem cells(MSCs),and MSCs from gingiva.We then focus on how these stem cells are regulated by bone morphogenetic protein(BMP)and/or Wnt signaling by examining the interplays between these pathways.Lastly,we analyze the current status of dental tissue engineering strategies that utilize oral/dental stem cells by harnessing the interplays between BMP and Wnt pathways.We also highlight the challenges that must be addressed before the dental stem cells may reach any clinical applications.Thus,we can expect to witness significant progresses to be made in regenerative dentistry in the coming decade.展开更多
Bone morphogenetic protein 9(BMP9)(or GDF2)was originally identified from fetal mouse liver cDNA libraries.Emerging evidence indicates BMP9 exerts diverse and pleiotropic functions during postnatal development and in ...Bone morphogenetic protein 9(BMP9)(or GDF2)was originally identified from fetal mouse liver cDNA libraries.Emerging evidence indicates BMP9 exerts diverse and pleiotropic functions during postnatal development and in maintaining tissue homeostasis.However,the expression landscape of BMP9 signaling during development and/or in adult tissues remains to be analyzed.Here,we conducted a comprehensive analysis of the expression landscape of BMP9 and its signaling mediators in postnatal mice.By analyzing mouse ENCODE transcriptome datasets we found Bmp9 was highly expressed in the liver and detectable in embryonic brain,adult lungs and adult placenta.We next conducted a comprehensive qPCR analysis of RNAs isolated from major mouse tissues/organs at various ages.We found that Bmp9 was highly expressed in the liver and lung tissues of young adult mice,but decreased in older mice.Interestingly,Bmp9 was only expressed at low to modest levels in developing bones.BMP9-associated TGFβ/BMPR type I receptor Alk1 was highly expressed in the adult lungs.Furthermore,the feedback inhibitor Smads Smad6 and Smad7 were widely expressed in mouse postnatal tissues.However,the BMP signaling antagonist noggin was highly expressed in fat and heart in the older age groups,as well as in kidney,liver and lungs in a biphasic fashion.Thus,our findings indicate that the circulating BMP9 produced in liver and lungs may account for its pleiotropic effects on postnatal tissues/organs although possible roles of BMP9 signaling in liver and lungs remain to be fully understood.展开更多
基金supported by National Natural Science Foundation of China(No.62071253)Postgraduate Research and Practice Innovation Program of Jiangsu Province(KYCX210747).
文摘In this paper,we investigate the system performance of a heterogeneous cellular network consisting of a macro cell and a small cell,where each cell has one user and one base station with multiple antennas.The macro base station(MBS)and the small base station(SBS)transmit their confidential messages to the macro user(MU)and the small user(SU)over their shared spectrum respectively.To enhance the system sum rate(SSR)of MBS-MU and SBS-SU transmission,we propose joint antenna selection combined with optimal power allocation(JAS-OPA)scheme and independent antenna selection combined with optimal power allocation(IAS-OPA)scheme.The JAS-OPA scheme requires to know the channel state information(CSI)of transmission channels and interference channels,while the IAS-OPA scheme only needs to know the CSI of transmission channels.In addition,we carry out the analysis for conventional round-robin antenna selection combined with optimal power allocation(RR-OPA)as a benchmark scheme.We formulate the SSR maximization problem through the power allocation between MBS and SBS and propose iterative OPA algorithms for JAS-OPA,IAS-OPA and RR-OPA schemes,respectively.The results show that the OPA schemes outperform the equal power allocation in terms of SSR.Moreover,we provide the closed-form expression of the system outage probability(SOP)for IAS scheme and RR scheme,it shows the SOP performance can be significantly improved by our proposed IAS scheme compared with RR scheme.
基金supported by the National Natural Science Foundation of China(Grant Nos.61522109,61671253,61571037and 91738201)the Fundamental Research Funds for the Central Universities(No.2016JBZ006)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20150040and BK20171446)the Key Project of Natural Science Research of Higher Education Institutions of Jiangsu Province(No.15KJA510003)
文摘The fifth generation （5G） wireless communication is currently a hot research topic and wireless communication systems on high speed railways （HSR） are important applications of 5G technologies. Existing stud- ies about 5G wireless systems on high speed railways （HSR） often utilize ideal channel parameters and are usually based on simple scenarios. In this paper, we evaluate the down- link throughput of 5G HSR communication systems on three typical scenarios including urban, cutting and viaduct with three different channel estimators. The channel parameters of each scenario are generated with tapped delay line （TDL） models through ray-tracing sim- ulations, which can be considered as a good match to practical situations. The channel estimators including least square （LS）, linear minimum mean square error （LMMSE）, and our proposed historical information based ba- sis expansion model （HiBEM）. We analyze the performance of the HiBEM estimator in terms of mean square error （MSE） and evaluate the system throughputs with different channel estimates over each scenario. Simulation results are then provided to corroborate our proposed studies. It is shown that our HiBEM estimator outperforms other estimators and that the sys-tem throughput can reach the highest point in the viaduct scenario.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61522109, 61631020, 61671253 and 91738201)the Natural Science Foundation of Jiangsu Province (Grant Nos. BK20150040, BK20171446 and BRA2018043)
文摘In this paper, we consider a multi-relay cooperative communication network that consists of a source node transmitting to its destination with the help of multiple decode-and- forward (DF) relays. Specifically, the DF relays that succeed in decoding the source signal are allowed to re-transmit their decoded results simultaneously to the destination in a cooperative beamforming manner. In order to carry out the cooperative beamforming, the destination needs to send the quantized channel state information (CSI) to the relays through a limited feedback channel in the face of channel quantization errors (CQE). We propose a CQE oriented multi-relay beamforming (MRB) scheme, denoted CQE-MRB for short, for the sake of improving the throughput of relay-destination transmissions. An effective throughput defined as the difference between the transmission rate and the feedback rate is used to measure an outage probability of the source-destination transmission. Simulation results demonstrate that the outage performance of proposed CQEMRB scheme is improved substantially with an increasing number of relays. Moreover, it is shown that the number of channel quantization bits can be further optimized to minimize the outage probability of proposed CQE-MRB scheme.
文摘The ever increasing wireless data services, such asimaging, video, audio, multimedia, etc., have de-mands for the very high speed wireless communicationsand network, which are unfortunately a bottleneck whencombining with the wireline core network. Users＇ arenow expecting high quality of experience with low-costdevices, ubiquitous connectivity, energy efficiency, highreliability, or even ultra-low latency if a vehicle terminalis applied.
文摘With the massive increase of wirelessly connected devices and the rapid development of the Internet, information is transmitted more and more frequently. Since the information transmissions over these networks are greatly threatened not only by the imperfection of channels but also by the potential attackers or eavesdroppers, security and reliability become some of the crucial requirements for our future networks. Due to the complex dynamic behavior, ergodicity, wide spectrum and sensitivity to initial values, chaos signals show most required attributes of good cryptosystems and great potentials in optical fiber communications for desirable spatial accuracy and distance. In this context, it has become imperative to investigate and apply chaos theories to solve emerging secure communication problems in various networks. This includes leveraging chaos systems and signals to address a wide range of secure communication challenges in optical fiber communications, chaos cipher, image encryption, etc.
基金The authors apologize to those investigators whose original work was not cited due to space constraints.The authors’research was supported in part by research grants from the National Institutes of Health(AT004418&AR054381 to TCH&HHL)Scoliosis Research Society(MJL&TCH),the 973 Program of Ministry of Science and Technology(MOST)of China(#2011CB707900 to TCH),the National Natural Science Foundation of China(#81400493 to FZ)+2 种基金Chongqing Municipal Commissions on Education(#KJ130303 to JW)Chongqing Municipal Commissions on Science&Technology(#cstc2013jcyjA0093 to JW)Chongqing Municipal Commissions Yubei District Science&Technology(#2014 Society of Human Resource Unit 14 to JW).MKM was a recipient of Howard Hughes Medical Institute Medical Research Fellowship.
文摘Tooth is a complex hard tissue organ and consists of multiple cell types that are regulated by important signaling pathways such as Wnt and BMP signaling.Serious injuries and/or loss of tooth or periodontal tissues may significantly impact aesthetic appearance,essential oral functions and the quality of life.Regenerative dentistry holds great promise in treating oral/dental disorders.The past decade has witnessed a rapid expansion of our understanding of the biological features of dental stem cells,along with the signaling mechanisms governing stem cell self-renewal and differentiation.In this review,we first summarize the biological characteristics of seven types of dental stem cells,including dental pulp stem cells,stem cells from apical papilla,stem cells from human exfoliated deciduous teeth,dental follicle precursor cells,periodontal ligament stem cells,alveolar bone-derived mesenchymal stem cells(MSCs),and MSCs from gingiva.We then focus on how these stem cells are regulated by bone morphogenetic protein(BMP)and/or Wnt signaling by examining the interplays between these pathways.Lastly,we analyze the current status of dental tissue engineering strategies that utilize oral/dental stem cells by harnessing the interplays between BMP and Wnt pathways.We also highlight the challenges that must be addressed before the dental stem cells may reach any clinical applications.Thus,we can expect to witness significant progresses to be made in regenerative dentistry in the coming decade.
基金The reported work was supported in part by research grants from the National Institutes of Health(CA226303 to TCH)the U.S.Department of Defense(OR130096 to JMW)+3 种基金the Scoliosis Research Society(TCH and MJL)This project was also supported in part by The University of Chicago Cancer Center Support Grant(P30CA014599)the National Center for Advancing Translational Sciences of the National Institutes of Health through Grant Number UL1 TR000430.TCH was also supported by the Mabel Green Myers Research Endowment Fund and The University of Chicago Orthopaedics Alumni Fund.Funding sources were not involved in the study design,in the collection,analysis and interpretation of datain the writing of the report,and in the decision to submit the paper for publication。
文摘Bone morphogenetic protein 9(BMP9)(or GDF2)was originally identified from fetal mouse liver cDNA libraries.Emerging evidence indicates BMP9 exerts diverse and pleiotropic functions during postnatal development and in maintaining tissue homeostasis.However,the expression landscape of BMP9 signaling during development and/or in adult tissues remains to be analyzed.Here,we conducted a comprehensive analysis of the expression landscape of BMP9 and its signaling mediators in postnatal mice.By analyzing mouse ENCODE transcriptome datasets we found Bmp9 was highly expressed in the liver and detectable in embryonic brain,adult lungs and adult placenta.We next conducted a comprehensive qPCR analysis of RNAs isolated from major mouse tissues/organs at various ages.We found that Bmp9 was highly expressed in the liver and lung tissues of young adult mice,but decreased in older mice.Interestingly,Bmp9 was only expressed at low to modest levels in developing bones.BMP9-associated TGFβ/BMPR type I receptor Alk1 was highly expressed in the adult lungs.Furthermore,the feedback inhibitor Smads Smad6 and Smad7 were widely expressed in mouse postnatal tissues.However,the BMP signaling antagonist noggin was highly expressed in fat and heart in the older age groups,as well as in kidney,liver and lungs in a biphasic fashion.Thus,our findings indicate that the circulating BMP9 produced in liver and lungs may account for its pleiotropic effects on postnatal tissues/organs although possible roles of BMP9 signaling in liver and lungs remain to be fully understood.
