Traditional chaotic pulse position modulation(CPPM)system has many drawbacks.It introduces delay into the feedback loop,which will lead to divergence of chaotic map easily.The wrong decision of data will cause error p...Traditional chaotic pulse position modulation(CPPM)system has many drawbacks.It introduces delay into the feedback loop,which will lead to divergence of chaotic map easily.The wrong decision of data will cause error propagation.Mismatch of parameters and synchronization error between the receiver and transmitter will arouse high bit error rate.To solve these problems,a demodulation algorithm of CPPM based on particle filtering is proposed.According to the mathematical model of the system,it tracks the real signal by online separation in demodulation.Simulation results show that the proposed method can track the true signal better than the traditional CPPM scheme.What's more,it has good synchronization robustness,reduced error propagation by wrong decision and low bit error rate.展开更多
This paper proposes a novel session setup mechanism in IMS(IP Multimedia Subsystem) by introducing the functional entity termed VSS(Visitor Subscriber Server) which is used to provide registration and location managem...This paper proposes a novel session setup mechanism in IMS(IP Multimedia Subsystem) by introducing the functional entity termed VSS(Visitor Subscriber Server) which is used to provide registration and location management.The new mechanism aims at improving session setup procedure by a betterment of location management in IMS.Through the use of two-tier subscriber information database constituted by the HSS(Home Subscriber Server) and the VSS, the new mechanism seperates the registration procedure and location management from the S-CSCF(Serving-Call'Session Control Function), and makes them be handled by the VSS.At the same time, the new mechanism updates the signaling procedure of registration and session setup.With VSS based location management, the cost of registeration and session setup procedure as well as the delay of session setup procedure become lower.The cost and delay functions of the new session setup mechanism as well as the cost function of new registeration are deduced.Then, simulations and analysis verify that the performance of this new mechanism gets the benefit in cost and time.展开更多
We investigate the position dependent spontaneous emission spectra of a A-type three-level atom with one transition coupled to the free vacuum reservoir and the other one coupled to a double-band photonic band gap res...We investigate the position dependent spontaneous emission spectra of a A-type three-level atom with one transition coupled to the free vacuum reservoir and the other one coupled to a double-band photonic band gap reservoir with a defect mode in the band gap. It is shown that, for the atom at the defect location, we have a two-peak spectrum with a wide dark line due to the strong coupling between the atom and the defect mode. While, when the atom is far from the defect location （or in the absence of the defect mode）, the spectrum has three peaks with two dark lines due to the coupling between the atom and the photonic band gap reservoir with the largest density of states near the band edges. On the other hand, we have a four-peak spectrum for the atom at the space in between. Moreover, the average spontaneous emission spectra of the atoms uniformly embedded in high dielectric or low dielectric regions are described. It is shown that the atoms embedded in high （low） dielectric regions far from the defect location, effectively couple to the modes of the lower （upper） photonic band. However, the atoms embedded in high dielectric or low dielectric regions at the defect location, are coupled mainly to the defect modes. While, the atoms uniformly embedded in high （low） dielectric regions with a normal distance from the defect location, are coupled to both of defect and lower （upper） photonic band modes.展开更多
基金Supported by the National Natural Science Foundation of China(No.41074090)Henan Science and Technology Key Project(No.092102210360)+1 种基金Henan Provincial Department of Education Science ang Technology Key Project(No.13A510330)Doctorate Program of Henan Polytechnic University(No.B2009-27)
文摘Traditional chaotic pulse position modulation(CPPM)system has many drawbacks.It introduces delay into the feedback loop,which will lead to divergence of chaotic map easily.The wrong decision of data will cause error propagation.Mismatch of parameters and synchronization error between the receiver and transmitter will arouse high bit error rate.To solve these problems,a demodulation algorithm of CPPM based on particle filtering is proposed.According to the mathematical model of the system,it tracks the real signal by online separation in demodulation.Simulation results show that the proposed method can track the true signal better than the traditional CPPM scheme.What's more,it has good synchronization robustness,reduced error propagation by wrong decision and low bit error rate.
基金National Science Fund for Distin-guished Young Scholars (No. 60525110)National 973 Program (No. 2007CB307100, 2007CB307103)+1 种基金Program for New Century Excellent Talents in University (No.NCET-04-0111)Development Fund Project for Electronic and Information Industry (Mobile Service and Application System Based on 3G)
文摘This paper proposes a novel session setup mechanism in IMS(IP Multimedia Subsystem) by introducing the functional entity termed VSS(Visitor Subscriber Server) which is used to provide registration and location management.The new mechanism aims at improving session setup procedure by a betterment of location management in IMS.Through the use of two-tier subscriber information database constituted by the HSS(Home Subscriber Server) and the VSS, the new mechanism seperates the registration procedure and location management from the S-CSCF(Serving-Call'Session Control Function), and makes them be handled by the VSS.At the same time, the new mechanism updates the signaling procedure of registration and session setup.With VSS based location management, the cost of registeration and session setup procedure as well as the delay of session setup procedure become lower.The cost and delay functions of the new session setup mechanism as well as the cost function of new registeration are deduced.Then, simulations and analysis verify that the performance of this new mechanism gets the benefit in cost and time.
文摘We investigate the position dependent spontaneous emission spectra of a A-type three-level atom with one transition coupled to the free vacuum reservoir and the other one coupled to a double-band photonic band gap reservoir with a defect mode in the band gap. It is shown that, for the atom at the defect location, we have a two-peak spectrum with a wide dark line due to the strong coupling between the atom and the defect mode. While, when the atom is far from the defect location （or in the absence of the defect mode）, the spectrum has three peaks with two dark lines due to the coupling between the atom and the photonic band gap reservoir with the largest density of states near the band edges. On the other hand, we have a four-peak spectrum for the atom at the space in between. Moreover, the average spontaneous emission spectra of the atoms uniformly embedded in high dielectric or low dielectric regions are described. It is shown that the atoms embedded in high （low） dielectric regions far from the defect location, effectively couple to the modes of the lower （upper） photonic band. However, the atoms embedded in high dielectric or low dielectric regions at the defect location, are coupled mainly to the defect modes. While, the atoms uniformly embedded in high （low） dielectric regions with a normal distance from the defect location, are coupled to both of defect and lower （upper） photonic band modes.
