Research On Key Techniques Of Radio Resource Allocation In Relay-enhanced Cellular Networks

Klystron is to focus the electron beam as the medium.In the electronic transition process,the electron beam transfroms the velocity modulation to the density modulation.As the same time,DC energy transforms into the energy of high frequency.Klystron, when is used as end power amplifier in high power miscrowave electronic system, is greatly applied in various civil and military miscrowave electronic system.Because effiency is a very important element influencing its application, to futher improve the klystron effiency is one development direction in the future.Through discussion of different parameters, there comes a conclusion[1,2]:1) If the frequency of the last several cavities is tuned higher than center frequency or higher than high-end frequency of the bandwidth, the bunching is increased, as well as the efficiency of beam-wave interaction.2) The efficiency is highest when the perveance is around0.5μp, but the perveance should be choosen due to other requirement.3) When the drift tube filling coefficient is constant, the normalized electronic note radius is between0.5and0.6to get higher effiency.4) When the radius of drift-tube is constant, the larger the drift tube filling coefficient is, the higher beam-wave interaction and efficiency is.5) Generally, the transit angle between the output cavity and the penultimate cavity is chosen25°～45°, and transit angle between the penultimate cavity and pre-penultimate cavity is chosen45°～50°6) Output gap impedance is adapted Rout=(1.2-1.5)Z0and Rout=[(1+0.5(γeb)2)|M2]Z0respectively in narrow-band and wide-band klystron,on the condition that the gap impedance doesn’t result in electron reverse.Through the efficiency analysis, a C-band high power klystron with high efficiencyis designed and the hot test data is accord with the requirement.Also a comparison of efficiency of three types C-band klystron is discussed.Through the comparison to three kinds of the same series of C band klystron,the analysis of different design parameters influence on the test result ofefficiency arepertormed.The results verify the analysis of various factors influencing the efficiencytheory,and provide a reference for future work.