The uplink massive multiple-input multiple-output(MIMO)status update system is very concerned about information freshness performance,especially for some central control Internet of Things(IoT)applications.In this con...The uplink massive multiple-input multiple-output(MIMO)status update system is very concerned about information freshness performance,especially for some central control Internet of Things(IoT)applications.In this context,age of information(AoI),as the metric of information freshness,gets more and more recognition,and simultaneously,the status packet blocklength plays an important role in improving the information freshness.In this work,we firstly consider a case with perfect channel state information(CSI)at the base station(BS),and derive the closed-form expression of the average AoI by using the Shannon theory.Guided by this,we obtain the tradeoff relationship among the status packet blocklength,transmission time and transmission failure probability.Accordingly,we optimize the status packet blocklength to minimize the average AoI.Then,we consider a more practical case with finite blocklength and imperfect CSI at the BS.In this case,we exploit pilot sequence to assist channel estimation,and derive an approximated closed-form expression of the average AoI according to short packet communication theory.It is found that increasing pilot block-length can improve the accuracy of channel estimation but reduce the frequency of status updates.Hence,we jointly optimize the pilot blocklength and status packet blocklength to improve the AoI performance.Extensive simulation results validate that the proposed methods can achieve almost the same performance as the exhaustive search methods.展开更多
In this paper,the covert age of information(CAoI),which characterizes the timeliness and covertness performance of communication,is first investigated in the short-packet covert communication with time modulated retro...In this paper,the covert age of information(CAoI),which characterizes the timeliness and covertness performance of communication,is first investigated in the short-packet covert communication with time modulated retrodirective array(TMRDA).Specifically,the TMRDA is designed to maximize the antenna gain in the target direction while the side lobe is sufficiently suppressed.On this basis,the covertness constraint and CAoI are derived in closed form.To facilitate the covert transmission design,the transmit power and block-length are jointly optimized to minimize the CAoI,which demonstrates the trade-off between covertness and timelessness.Our results illustrate that there exists an optimal block-length that yields the minimum CAoI,and the presented optimization results can achieve enhanced performance compared with the fixed block-length case.Additionally,we observe that smaller beam pointing error at Bob leads to improvements in CAoI.展开更多
To solve the problem of delayed update of spectrum information(SI) in the database assisted dynamic spectrum management(DB-DSM), this paper studies a novel dynamic update scheme of SI in DB-DSM. Firstly, a dynamic upd...To solve the problem of delayed update of spectrum information(SI) in the database assisted dynamic spectrum management(DB-DSM), this paper studies a novel dynamic update scheme of SI in DB-DSM. Firstly, a dynamic update mechanism of SI based on spectrum opportunity incentive is established, in which spectrum users are encouraged to actively assist the database to update SI in real time. Secondly, the information update contribution(IUC) of spectrum opportunity is defined to describe the cost of accessing spectrum opportunity for heterogeneous spectrum users, and the profit of SI update obtained by the database from spectrum allocation. The process that the database determines the IUC of spectrum opportunity and spectrum user selects spectrum opportunity is mapped to a Hotelling model. Thirdly, the process of determining the IUC of spectrum opportunities is further modelled as a Stackelberg game by establishing multiple virtual spectrum resource providers(VSRPs) in the database. It is proved that there is a Nash Equilibrium in the game of determining the IUC of spectrum opportunities by VSRPs. Finally, an algorithm of determining the IUC based on a genetic algorithm is designed to achieve the optimal IUC. The-oretical analysis and simulation results show that the proposed method can quickly find the optimal solution of the IUC, and ensure that the spectrum resource provider can obtain the optimal profit of SI update.展开更多
OBJECTIVE: To investigate the effects of shikonin(SKN) on M1 and M2 polarization of macrophages both in vitro and in vivo. METHODS: Collagen-induced arthritis(CIA) in male DBA/1 mice were treated with a dose of 4 mg/k...OBJECTIVE: To investigate the effects of shikonin(SKN) on M1 and M2 polarization of macrophages both in vitro and in vivo. METHODS: Collagen-induced arthritis(CIA) in male DBA/1 mice were treated with a dose of 4 mg/kg/day of SKN for 23 d(n = 6/group). The histopathology of inflamed joints in CIA mice was evaluated to test the antiarthritic effect of SKN. M1/M2 polarization of macrophages induced by lipopolysaccharide(LPS) and interferon(IFN)-γ or interleukin(IL)-4 and IL-13, were used to assess the effect of SKN(0.05, 0.1, and 0.2 μM). The effect of SKN on the protein expression of nitric oxide synthase, arginase, CD68, and CD206 was evaluated using western blot analysis. RESULTS: The results of this study revealed that SKN delayed the arthritis feet symptom score, reduced the incidence rate of arthritis, and relieved the inflammation of joints in CIA mice. SKN inhibited M1 macrophage polarization but did not affect M2 macrophage polarization in the joints of CIA mice. Moreover, SKN inhibited M1 polarization induced by LPS and IFN-γ, but did not affect M2 polarization induced by IL-4 and IL-13. CONCLUSION: These findings suggest that SKN alleviated CIA through inhibiting M1 macrophage polarization and has great potential as a new drug for RA treatment.展开更多
Cognitive Radio(CR) is a promising technology to solve the challenging spectrum scarcity problem.However, to implement CR, spectrum sensing is the groundwork and the precondition.In this paper, a collaborative spectru...Cognitive Radio(CR) is a promising technology to solve the challenging spectrum scarcity problem.However, to implement CR, spectrum sensing is the groundwork and the precondition.In this paper, a collaborative spectrum sensing scheme using fuzzy comprehensive evaluation is proposed.The final sensing decision of the proposed scheme is based on the combination of distributed sensing results of different Secondary Users(SUs).To improve the reliability of the sensing decision, the combination procedure takes into account the credibility of each SU, which is evaluated using fuzzy comprehensive evaluation.The effect of the presence of malicious SUs and malfunctioning SUs on the performance of the proposed scheme is also investigated.The efficiency of the scheme is validated through analysis and simulation.展开更多
Compared with the traditional channel estimation methods, blind channel estimation methods can increase the bandwidth efficiency of the systems, but their precision is low and they converge slowly. In this paper, the ...Compared with the traditional channel estimation methods, blind channel estimation methods can increase the bandwidth efficiency of the systems, but their precision is low and they converge slowly. In this paper, the Cramér-Rao Bound （CRB） for blind channel estimation in complex-valued Single-Input Multiple- Output （SIMO） channel is derived. In the simulations, the correctness of the CRB is validated and some channel estimation methods are evaluated by using the CRB.展开更多
Due to the broadcast nature of wireless transmission medium,security threats may hinder propagation of cognitive radio systems for commercial and military data application. This paper sets a channel error analytical f...Due to the broadcast nature of wireless transmission medium,security threats may hinder propagation of cognitive radio systems for commercial and military data application. This paper sets a channel error analytical framework and studies the joint impact of estimation errors and feedback delay on secrecy performance in cognitive radio networks. Under the assumption that system applies beamforming and jamming scheme,a multi-antenna cognitive base station( CBS) sends confidential signals to a secondary user( SU) in the presence of M primary users( PUs) and an eavesdropper. Assuming only imperfect channel state information( CSI) about the receivers is available,secrecy rate,outage probability,secrecy throughput are deduced to obtain a closed-form expression. It is shown that while the transmit power increases,secrecy throughput would reach to a constant. Simulation results show that feedback delay adversely impacts on secrecy rate,connection outage probability and secrecy throughput,while estimation error causes more impact on secrecy outage probability. Furthermore,the secrecy rate could increase progressively with the transmit power only if there exists no feedback delay.展开更多
The outage performance of OFDM-based decode-and-forward cooperative networks is studied. The channels are modeled as independent Weibull distributed coefficients. A closed-form expression for the outage probability is...The outage performance of OFDM-based decode-and-forward cooperative networks is studied. The channels are modeled as independent Weibull distributed coefficients. A closed-form expression for the outage probability is obtained for three selective relaying schemes in the Weibull fading channels and a derived optimum power allocation method based on the closed form expressions of outage probability debases the outage probability. Monte Carlo simulations verify the analytical results.展开更多
文摘The uplink massive multiple-input multiple-output(MIMO)status update system is very concerned about information freshness performance,especially for some central control Internet of Things(IoT)applications.In this context,age of information(AoI),as the metric of information freshness,gets more and more recognition,and simultaneously,the status packet blocklength plays an important role in improving the information freshness.In this work,we firstly consider a case with perfect channel state information(CSI)at the base station(BS),and derive the closed-form expression of the average AoI by using the Shannon theory.Guided by this,we obtain the tradeoff relationship among the status packet blocklength,transmission time and transmission failure probability.Accordingly,we optimize the status packet blocklength to minimize the average AoI.Then,we consider a more practical case with finite blocklength and imperfect CSI at the BS.In this case,we exploit pilot sequence to assist channel estimation,and derive an approximated closed-form expression of the average AoI according to short packet communication theory.It is found that increasing pilot block-length can improve the accuracy of channel estimation but reduce the frequency of status updates.Hence,we jointly optimize the pilot blocklength and status packet blocklength to improve the AoI performance.Extensive simulation results validate that the proposed methods can achieve almost the same performance as the exhaustive search methods.
文摘In this paper,the covert age of information(CAoI),which characterizes the timeliness and covertness performance of communication,is first investigated in the short-packet covert communication with time modulated retrodirective array(TMRDA).Specifically,the TMRDA is designed to maximize the antenna gain in the target direction while the side lobe is sufficiently suppressed.On this basis,the covertness constraint and CAoI are derived in closed form.To facilitate the covert transmission design,the transmit power and block-length are jointly optimized to minimize the CAoI,which demonstrates the trade-off between covertness and timelessness.Our results illustrate that there exists an optimal block-length that yields the minimum CAoI,and the presented optimization results can achieve enhanced performance compared with the fixed block-length case.Additionally,we observe that smaller beam pointing error at Bob leads to improvements in CAoI.
文摘To solve the problem of delayed update of spectrum information(SI) in the database assisted dynamic spectrum management(DB-DSM), this paper studies a novel dynamic update scheme of SI in DB-DSM. Firstly, a dynamic update mechanism of SI based on spectrum opportunity incentive is established, in which spectrum users are encouraged to actively assist the database to update SI in real time. Secondly, the information update contribution(IUC) of spectrum opportunity is defined to describe the cost of accessing spectrum opportunity for heterogeneous spectrum users, and the profit of SI update obtained by the database from spectrum allocation. The process that the database determines the IUC of spectrum opportunity and spectrum user selects spectrum opportunity is mapped to a Hotelling model. Thirdly, the process of determining the IUC of spectrum opportunities is further modelled as a Stackelberg game by establishing multiple virtual spectrum resource providers(VSRPs) in the database. It is proved that there is a Nash Equilibrium in the game of determining the IUC of spectrum opportunities by VSRPs. Finally, an algorithm of determining the IUC based on a genetic algorithm is designed to achieve the optimal IUC. The-oretical analysis and simulation results show that the proposed method can quickly find the optimal solution of the IUC, and ensure that the spectrum resource provider can obtain the optimal profit of SI update.
基金Supported by Traditional Chinese Medicine Bureau of Guangdong Province:the Role and Mechanism of Ermiao San in the Regulation of Th cell Differentiation by PKC-? in the Treatment of RA (No. 20211333)National Natural Science Foundation of China:the Role and Mechanism of CD4+T Cell Smad7 Loss in the Pathogenesis of Rheumatoid Arthritis(No. 81974253)+4 种基金the Significance of Regulating Glycolytic Metabolism by HK-2 in Dendritic Cell Migration and RA Pathogenesis (No. 81901641)Shenzhen Science and Technology Innovation Committee:Research on Key Technologies of Intelligent Robot Based on Artificial Intelligence Image Data (No. GJHZ20200731095208025)Municipal Development and Reform Commission:Virtual Reality Clinical Application Public Service Platform (XMHT20190104001)Project of Shenzhen Municipal Health Commission:Biological Markers in Idiopathic Inflammatory Myopathy and Clinical Significance of Tumorigenesis (No. SZXJ2017046)Nature Science Foundation of Guangdong Province:Experimental Study on Treatment of Rabbit Rheumatoid Arthritis with Lipidated Methotrexate Microbubbles Combined with Controlled Release by Ultrasonic Irradiation (No. 2018A030313281)。
文摘OBJECTIVE: To investigate the effects of shikonin(SKN) on M1 and M2 polarization of macrophages both in vitro and in vivo. METHODS: Collagen-induced arthritis(CIA) in male DBA/1 mice were treated with a dose of 4 mg/kg/day of SKN for 23 d(n = 6/group). The histopathology of inflamed joints in CIA mice was evaluated to test the antiarthritic effect of SKN. M1/M2 polarization of macrophages induced by lipopolysaccharide(LPS) and interferon(IFN)-γ or interleukin(IL)-4 and IL-13, were used to assess the effect of SKN(0.05, 0.1, and 0.2 μM). The effect of SKN on the protein expression of nitric oxide synthase, arginase, CD68, and CD206 was evaluated using western blot analysis. RESULTS: The results of this study revealed that SKN delayed the arthritis feet symptom score, reduced the incidence rate of arthritis, and relieved the inflammation of joints in CIA mice. SKN inhibited M1 macrophage polarization but did not affect M2 macrophage polarization in the joints of CIA mice. Moreover, SKN inhibited M1 polarization induced by LPS and IFN-γ, but did not affect M2 polarization induced by IL-4 and IL-13. CONCLUSION: These findings suggest that SKN alleviated CIA through inhibiting M1 macrophage polarization and has great potential as a new drug for RA treatment.
基金Supported by the National Natural Science Foundation of China (No.60672079)the Natural Science Foundation of Jiangsu Province (No.BK2006701 and No. BK2007002)
文摘Cognitive Radio(CR) is a promising technology to solve the challenging spectrum scarcity problem.However, to implement CR, spectrum sensing is the groundwork and the precondition.In this paper, a collaborative spectrum sensing scheme using fuzzy comprehensive evaluation is proposed.The final sensing decision of the proposed scheme is based on the combination of distributed sensing results of different Secondary Users(SUs).To improve the reliability of the sensing decision, the combination procedure takes into account the credibility of each SU, which is evaluated using fuzzy comprehensive evaluation.The effect of the presence of malicious SUs and malfunctioning SUs on the performance of the proposed scheme is also investigated.The efficiency of the scheme is validated through analysis and simulation.
基金Supported by Jiangsu Natural Science Fund (BK2003015) National Mobile Communications Research Laboratory Fund (N0302).
文摘Compared with the traditional channel estimation methods, blind channel estimation methods can increase the bandwidth efficiency of the systems, but their precision is low and they converge slowly. In this paper, the Cramér-Rao Bound （CRB） for blind channel estimation in complex-valued Single-Input Multiple- Output （SIMO） channel is derived. In the simulations, the correctness of the CRB is validated and some channel estimation methods are evaluated by using the CRB.
基金Supported by the National Natural Science Foundation of China(No.61371122,61471393)the China Postdoctoral Science Foundation under a Special Financial Grant(No.2013T60912)
文摘Due to the broadcast nature of wireless transmission medium,security threats may hinder propagation of cognitive radio systems for commercial and military data application. This paper sets a channel error analytical framework and studies the joint impact of estimation errors and feedback delay on secrecy performance in cognitive radio networks. Under the assumption that system applies beamforming and jamming scheme,a multi-antenna cognitive base station( CBS) sends confidential signals to a secondary user( SU) in the presence of M primary users( PUs) and an eavesdropper. Assuming only imperfect channel state information( CSI) about the receivers is available,secrecy rate,outage probability,secrecy throughput are deduced to obtain a closed-form expression. It is shown that while the transmit power increases,secrecy throughput would reach to a constant. Simulation results show that feedback delay adversely impacts on secrecy rate,connection outage probability and secrecy throughput,while estimation error causes more impact on secrecy outage probability. Furthermore,the secrecy rate could increase progressively with the transmit power only if there exists no feedback delay.
文摘The outage performance of OFDM-based decode-and-forward cooperative networks is studied. The channels are modeled as independent Weibull distributed coefficients. A closed-form expression for the outage probability is obtained for three selective relaying schemes in the Weibull fading channels and a derived optimum power allocation method based on the closed form expressions of outage probability debases the outage probability. Monte Carlo simulations verify the analytical results.
