An exact average symbol error rate analysis for the distributed dual-hop relay cooperative network with multiple relays in a Nakagami-m fading environment is presented.In the derivation of the moment generation functi...An exact average symbol error rate analysis for the distributed dual-hop relay cooperative network with multiple relays in a Nakagami-m fading environment is presented.In the derivation of the moment generation function of receiver Signal-to-Noise Ratio(SNR),the sectional integral method is used,instead of the cumulative density function method which is ordinarily used by the deduction of the outage probability of S-R-D link.The accurate symbol error rate of a dual-hop relay cooperative network is obtained with the closed-form Moment Genoration Function (MGF) expression.The correctness of the symbol error rate is verified through numerical simulations and is compared with other analytical methods.These deductions clearly show that the distributed cooperative diversity network presented has strong superiorities in overcoming severe fading and can achieve full diversity order.展开更多
The previous Decentralised Cognitive Medium Access Control(DC-MAC) protocol allows Secondary Users(SUs) to independently search for spectrum access opportunities without the need for a central coordinator.DC-MAC assum...The previous Decentralised Cognitive Medium Access Control(DC-MAC) protocol allows Secondary Users(SUs) to independently search for spectrum access opportunities without the need for a central coordinator.DC-MAC assumes that the detection scheme is ideal at the Physical(PHY) layer.In fact,a more complex detection algorithm is impractical in distributed spectrum sharing scenarios.Energy Detection(ED) at the PHY layer has become the most common method because of its low computational and implementation complexities.Thus,it is essential to integrate the DC-MAC with ED at the PHY layer.However,ED requires the Minimum Sampling Time(MST)duration to achieve the target detection probability in low Signal-to-Noise Ratio(SNR)environments.Otherwise,it cannot achieve the expected detection performance.In this paper,we derive an accurate expression of MST for ED in low SNR environments.Then,we propose an Optimised DC-MAC(ODC-MAC) protocol which is based on MST,and which amends the aforementioned problems of DC-MAC with ED.Moreover,the closed-form expressions for the unreliable data transmission probability are derived for both DC-MAC and ODC-MAC.We show that the simulation results agree well with the theoretical analyses.The proposed ODC-MAC can improve the data transmission reliability and enhance the throughput compared to the performance of the traditional DC-MAC.展开更多
In this paper,we propose a securityoriented transmission scheme with the help of multiple relays in Cognitive Radio(CR).To maximise the Secrecy Capacity(SC)of the source-destination link in CR,both beamforming and coo...In this paper,we propose a securityoriented transmission scheme with the help of multiple relays in Cognitive Radio(CR).To maximise the Secrecy Capacity(SC)of the source-destination link in CR,both beamforming and cooperative jamming technologies are used to improve the performance of the Secondary User(SU)and protect the Primary User(PU).The effectiveness of the proposed scheme is demonstrated using extensive simulation.Both theoretical analyses and simulation results reveal that the proposed scheme contributes to the secure transmission of the SU with acceptable attenuation of the Signal-to-Noise Ratio(SNR)at the PU receiver,and the upper bound of the SC at the SU receiver is able to exploit the power allocation strategy.展开更多
The biosynthesis of antibiotics is controlled by cascade regulation involving cluster-situated regulators (CSRs) and pleiotropic regulators. Three CSRs have been identified in the jadomycin biosynthetic gene cluster, ...The biosynthesis of antibiotics is controlled by cascade regulation involving cluster-situated regulators (CSRs) and pleiotropic regulators. Three CSRs have been identified in the jadomycin biosynthetic gene cluster, including one OmpR-type activator (JadR1) and two TetR-like repressors (JadR* and JadR2). To examine their interactions in jadomycin biosynthesis, a series of mutants were generated and tested for jadomycin production. We noticed that jadomycin production in the jadR*-jadR2 double mutant was increased dramatically compared with either single mutant. Transcriptional analysis showed that jadR* and jadR2 act synergistically to repress jadomycin production by inhibiting the transcription of jadR1. Furthermore, jadR* and jadR2 reciprocally inhibit each other. The complex interactions among these three CSRs may provide clues for the activation of the jadomycin gene cluster, which would otherwise remain silent without stimulation from stress signals.展开更多
Feedback plays an important role in various biological signal transmission systems. In this paper, a signaling cascade system(including three layers: input(S), intermediate(V), output(X) components) is employed to stu...Feedback plays an important role in various biological signal transmission systems. In this paper, a signaling cascade system(including three layers: input(S), intermediate(V), output(X) components) is employed to study the fluctuations and net synergy in information transmission, in which the V component is regulated by itself or the X component, and each feedback on V is either positive or negative. The Fano factor, the net synergy, and the signalto-noise ratio(SNR) of signaling cascade with the four possible feedback types are theoretically derived by using linear noise approximation of the master equation, and the ability of information transmission through the signaling cascade is characterized by using the partial information decomposition of information theory. It is found that the signaling cascade exhibits different responses to the four feedback mechanisms, which depend on the relationships between degradation rates of components. Our results not only clarify the dependence of the Fano factor, net synergy, and SNR on the feedback regulations with the varying of degradation rates of components, but also imply that living cells could utilize different feedback mechanisms to adapt to the external fluctuating environments.展开更多
基金supported by Important National Science ＆ Technology Specific Projects under Grant No.CX01011the Important National Science ＆ Technology Specific Projects under Grant No.4101002+2 种基金the National Natural Science Foundation of China under Grants No.61002014,No.60972017,No.60972018the Excellent Young Teachers Program of MOE,PRC under Grant No.2009110120028the Research Fund for the Doctoral Program of Higher Education under Grants No.20091101110019,No.20070007019
文摘An exact average symbol error rate analysis for the distributed dual-hop relay cooperative network with multiple relays in a Nakagami-m fading environment is presented.In the derivation of the moment generation function of receiver Signal-to-Noise Ratio(SNR),the sectional integral method is used,instead of the cumulative density function method which is ordinarily used by the deduction of the outage probability of S-R-D link.The accurate symbol error rate of a dual-hop relay cooperative network is obtained with the closed-form Moment Genoration Function (MGF) expression.The correctness of the symbol error rate is verified through numerical simulations and is compared with other analytical methods.These deductions clearly show that the distributed cooperative diversity network presented has strong superiorities in overcoming severe fading and can achieve full diversity order.
基金supported by the National Natural Science Foundation of China under Grants No.61271259,No.61301123the Chongqing Natural Science Foundation under Grant No.CTSC2011jjA40006+2 种基金the Research Project of Chongqing Education Commission under Grants No.KJ120501,No.KJ120502,No.KJ130536the Special Fund of Chongqing Key Laboratory(CSTC)the Project of Chongqing Municipal Education Commission under Grant No.Kjzh11206
文摘The previous Decentralised Cognitive Medium Access Control(DC-MAC) protocol allows Secondary Users(SUs) to independently search for spectrum access opportunities without the need for a central coordinator.DC-MAC assumes that the detection scheme is ideal at the Physical(PHY) layer.In fact,a more complex detection algorithm is impractical in distributed spectrum sharing scenarios.Energy Detection(ED) at the PHY layer has become the most common method because of its low computational and implementation complexities.Thus,it is essential to integrate the DC-MAC with ED at the PHY layer.However,ED requires the Minimum Sampling Time(MST)duration to achieve the target detection probability in low Signal-to-Noise Ratio(SNR)environments.Otherwise,it cannot achieve the expected detection performance.In this paper,we derive an accurate expression of MST for ED in low SNR environments.Then,we propose an Optimised DC-MAC(ODC-MAC) protocol which is based on MST,and which amends the aforementioned problems of DC-MAC with ED.Moreover,the closed-form expressions for the unreliable data transmission probability are derived for both DC-MAC and ODC-MAC.We show that the simulation results agree well with the theoretical analyses.The proposed ODC-MAC can improve the data transmission reliability and enhance the throughput compared to the performance of the traditional DC-MAC.
基金supported by the National Natural Science Foundation of China under Grants No. 61201150, No. 61171097the Fundamental Research Funds for the Central Universities of BUPT under Grant No. 2013RC0202the State Major Science and Technology Special Projects under Grant No. 2012ZX03004001
文摘In this paper,we propose a securityoriented transmission scheme with the help of multiple relays in Cognitive Radio(CR).To maximise the Secrecy Capacity(SC)of the source-destination link in CR,both beamforming and cooperative jamming technologies are used to improve the performance of the Secondary User(SU)and protect the Primary User(PU).The effectiveness of the proposed scheme is demonstrated using extensive simulation.Both theoretical analyses and simulation results reveal that the proposed scheme contributes to the secure transmission of the SU with acceptable attenuation of the Signal-to-Noise Ratio(SNR)at the PU receiver,and the upper bound of the SC at the SU receiver is able to exploit the power allocation strategy.
基金supported by grants from the Ministry of Science and Technology of China (2013CB734001, 2009CB118905)the National Natural Science Foundation of China (31270110, 31030003)
文摘The biosynthesis of antibiotics is controlled by cascade regulation involving cluster-situated regulators (CSRs) and pleiotropic regulators. Three CSRs have been identified in the jadomycin biosynthetic gene cluster, including one OmpR-type activator (JadR1) and two TetR-like repressors (JadR* and JadR2). To examine their interactions in jadomycin biosynthesis, a series of mutants were generated and tested for jadomycin production. We noticed that jadomycin production in the jadR*-jadR2 double mutant was increased dramatically compared with either single mutant. Transcriptional analysis showed that jadR* and jadR2 act synergistically to repress jadomycin production by inhibiting the transcription of jadR1. Furthermore, jadR* and jadR2 reciprocally inhibit each other. The complex interactions among these three CSRs may provide clues for the activation of the jadomycin gene cluster, which would otherwise remain silent without stimulation from stress signals.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11775091 and 11474117
文摘Feedback plays an important role in various biological signal transmission systems. In this paper, a signaling cascade system(including three layers: input(S), intermediate(V), output(X) components) is employed to study the fluctuations and net synergy in information transmission, in which the V component is regulated by itself or the X component, and each feedback on V is either positive or negative. The Fano factor, the net synergy, and the signalto-noise ratio(SNR) of signaling cascade with the four possible feedback types are theoretically derived by using linear noise approximation of the master equation, and the ability of information transmission through the signaling cascade is characterized by using the partial information decomposition of information theory. It is found that the signaling cascade exhibits different responses to the four feedback mechanisms, which depend on the relationships between degradation rates of components. Our results not only clarify the dependence of the Fano factor, net synergy, and SNR on the feedback regulations with the varying of degradation rates of components, but also imply that living cells could utilize different feedback mechanisms to adapt to the external fluctuating environments.
