Research And Implementation Of Multi-User Downlink Control Channel Based On TDD-LTE

Nowadays with the application of new technology,which includes cloud service and so on,and people’s strict requirements for modern communication technology,LTE has received great attention from its birth.The existing Long Term Evolution(LTE)is divided into Time Division Duplexing(Time Division Duplexing,TDD)and Frequency Division Duplexing(Frequency Division Duplexing,FDD).This paper analyzes and tests the multiuser physical downlink control channel(Physical Downlink Control Channel,PDCCH)of TDD-LTE and its realizing based on Digital Signal Processor(Digital Signal Processor,DSP)TMSC6670.First of all,the procedure of PDCCH is studied.Several important modules of PDCCH are carefully analyzed,such as cyclic redundancy check(Cyclic Redundancy Check,CRC)and rate matching(Rate Matching,RM),and building a simulation link on that.Under the typical channel conditions,the performance of different aggregation levels and different equilibrium modes of PDCCH is tested and analyzed.This paper adopts DSP TMSC6670 chip to realize the implementation of PDCCH link.This paper tests the data interaction between the SRIO/network port of the chip and other external devices.In this paper,the BCP coprocessor of the chip has been used to complete the CRC,coding,rate matching and other specific level operations.The VCP coprocessor completes the Viterbi decoding.The process of program implementation is analyzed,and the independent program is processed in parallel with the characteristics of the chip 4 core.In the LTE system,the performance of the equalization algorithm will greatly affect the performance of the system.In order to reduce the influence of noise on the stability of the system,two equilibria,which are called zero forcing and MMSE,are realized at the DSP fixed-point,and the DSP fixed-point performance under two equilibria is analyzed.Because semi-persistent scheduling(Semi-Persistent Scheduling,SPS)can effectively save the control information of the underlying interaction,this paper analyzes the relevant parameters of SPS and combs the three main processes of SPS: activating,transmission and release.This paper completes the implementation and the test of the downlink SPS on the DSP platform.For the dynamic scheduling,it highest needs 44 cycles to determine the success of blind detection in theory.When Semi-Persistent Scheduling is added,blind detection increases,which Greatly aggravating the processing burden.For meeting the running time requirements of LTE,optimizing the rate matching and the process of blind detection is a good way to reduce the time overhead of a program’s receiving end.At last,this paper builds the running environment and its main components.Full link tests on this platform,under multiple noise-signal ratio as well as multiple channels,and the obtained data compares with the data of the simulation link.