Research And Realization Of Physical Downlink Control Channel In LTE-A System

With the commercial development of the fourth generation mobile communication, LTE-A, the standard technology, achieves the goal of higher peak rates and system capacity. According to the demand of the major projects “TD-LTE-Advanced System Test Equipment Development” and “Application of the double codebook beamforming in Massive MIMO” in laboratory, this thesis mainly studies PDCCH and EPDCCH of TD-LTE-A system. The two channels carry DCI which is assigned by the base station to serve data channels. Get the correct DCI information is the key to ensure the normal operation of the communication.Firstly, system structure and key technologies in physical layer of LTE-A system have been introduced, and then the features of physical layer and downlink channels are briefly described. The core of PDCCH is blind detection, which mainly resolves the control information of downlink channel to inform the data channel associated configuration. The accomplished works in this thesis are as follow:1. The overall process of PDCCH is elaborated, including the simulation process and DSP implementation in each sending and receiving side. Besides, use the code to test a large number of physical layer data, by counting cycle number to verify efficiency and correctness.2. This thesis focuses on the process of PDCCH blind detection on the receiving side. In order to simplify the process of blind detection, this thesis studies and compares other blind detection algorithms. Then a power detection algorithm has been designed and implemented which can significantly simplify the implementation cycle of blind detection. The maximum number of blind detection is limited to 4 times. Camparing with the feedback algorithm, it reduces 3000 and 60000 cycle.3. Based on cross-carrier scheduling technique principle and new control signaling, the process of cross-carrier scheduling in PDCCH has been simulated. It can be seen from the result, UE is able to correctly analyze the DCI format of each cell in scheduling, so as to verify the correctness of the code.4. At last, this thesis also introduces EPDCCH in LTE-A which is used to improve control channel capacity and scheduling flexibility. Its resource elements, transition mode are totally different from that of PDCCH. Because of the resource mapping in data region, the process of EPDCCH has been designed. According to the new reference signal—DMRS of EPDCCH, this thesis studies a modified channel estimation algorithms. By using the similarity between the pilot signals, can be calculated easier. It can be seen from simulation result, the computational complexity of improved MMSE algorithms is only half of before. The error rate is closer when channel environment changed getting better, so the modified MMSE algorithm is used in the project.All the improvement program and optimization algorithms mentioned have been successfully applied to the actual project.