A 2×2 MIMO Throughput Analytical Model for RF Front End Optimization

With a given communication protocol,performance optimization of a multiple-input multipleoutput(MIMO)wireless system mainly lies on the design of the radio frequency(RF)front end.Currently,the optimization is mainly achieved based on experiences,such as promoting the multiple antenna gains and reducing their correlations.This experience-based method works to a certain extent,but is inefficient since the final performance impact by each sub-system is not quantified.The challenge lies on how to find the most limiting factor that restricts the overall communication throughput.This paper presents an analytical model for throughput calculations of 2×2 MIMO wireless system,which is built on a first step of maximum rate calculated under the chosen protocol and channel,followed by a second step of throughput baseline measurement,and continued with the third step of throughput calculations of the overall system according to the actual settings of subsystems.The model can provide a detailed diagnostic report of each RF factor,which will directly point out the imperfections and make the troubleshooting and debugging much more effective.Besides,throughput is analyzed in a mathematical approach that allows the performance more predictable during the design phase.

RF design of a compact 648 MHz single spoke cavity at CSNS

Purpose In order to increase CSNS beam power from 100 to 500 kW,the linac injection energy needs to be increased from 80 to 300 MeV.The combined layout of superconducting spoke cavities and lliptical cavities will be adopted to accelerate H-beam to 300 MeV.In this paper,a compact single spoke cavity withφ50-mm beam aperture was proposed,with the RF performance of the spoke cavity optimized to E_(p)/E_(acc).<5,E_(p)/E_(acc)<9,as well as the good multipacting behavior.Methods CST Microwave Studio was used to optimize the RF performance(E_(peak)/E_(acc),B_(peak)/E_(acc) R/Q)with cavity geometry parameters.After electromagnetic design was finished,multipacting behavior was studied with CST Particle Studio module,and cavity shape modification was made to get a reasonable<SEY>value.Results The simulation got optimum results of E_(peak)/E_(acc)=4.97 and B_(peak)/E_((acc)=8.42 mT/(MV/m),and the<SEY>max is 1.52at E_(acc)=7.74 MV/m.Conclusion A 648 MHzβ=0.4 single spoke cavity with beam apertureФ50 mm was proposed in the paper.This compact cavity may be a very promising option for CSNS linac upgrading.In addition to the optimization of the RF parameters,the multipacting behavior of the cavity is also studied,and cavity shape is optimized to reduce<SEY>value.

The run management system for CSNS

Purpose In order to increase CSNS beam power from 100 to 500 kW,the linac injection energy needs to be increased from 80 to 300 MeV.The combined layout of superconducting spoke cavities and elliptical cavities will be adopted to accelerate H−beam to 300 MeV.In this paper,a compact single spoke cavity withΦ50-mm beam aperture was proposed,with the RF performance of the spoke cavity optimized to Ep/Eacc<5,Bp/Eacc<9,as well as the good multipacting behavior.Methods CST Microwave Studio was used to optimize the RF performance(Epeak/Eacc,Bpeak/Eacc,R/Q)with cavity geometry parameters.After electromagnetic design was finished,multipacting behavior was studied with CST Particle Studio module,and cavity shape modification was made to get a reasonable<SEY>value.Results The simulation got optimum results of Epeak/Eacc=4.97 and Bpeak/Eacc=8.42 mT/(MV/m),and the<SEY>max is 1.52 at Eacc=7.74 MV/m.Conclusion A 648 MHzβg=0.4 single spoke cavity with beam apertureΦ50 mm was proposed in the paper.This compact cavity may be a very promising option for CSNS linac upgrading.In addition to the optimization of the RF parameters,the multipacting behavior of the cavity is also studied,and cavity shape is optimized to reduce<SEY>value.