Design And Implementation Of Physical Downlink Control Channel Fast Blind Detection

The Physical Downlink Control Channel(PDCCH)in 4G LTE system is used to carry the Downlink Control Information(DCI).The DCI includes scheduling decisions of uplink or downlink,and power-control commands of user equipment,from eNodeB to user equipment.In order to use resources of the control area effectively,and reduce the signaling cost of PDCCH,a blind detection method is used by user equipment to obtain DCI.The user equipment tentatively decodes all possible DCI formats and resource locations to find its own DCI without knowing the format and location chosen by eNodeB.Most proposed blind detection algorithms need many times of blind detection on software platform,which delays data transmission and reduces response speed of downlink communication.This paper aims to increase the speed of UE getting DCI by reducing times of invalid blind detection and speeding up the execution.Two methods to reduce the invalid blind detection times are proposed: one is detecting the invalid control channel elements in user equipment control information area,and eliminating the blind detection on these invalid resources.The other one is detecting whether the soft information satisfies the channel coding structure or not,to stop the invalid blind detection with wrong format and resource location setting.For the acceleration of specific blind detection process,hardware implementation on FPGA is used.The PDCCH blind detection with 3-level pipeline structure is implemented on FPGA to make full use of the parallelism on hardware.The experiment results show that the proposed two optimization algorithms can reduce the times of invalid blind detection by 50% at the SNR of 0dB.There is only one invalid blind detection when the SNR is greater than 5dB.The speed of blind detection based on hardware implementation can reach 10 times of the software version.