Study On Interference Optimization For Public Channels In LTE-A Hetnet System

Several low power network nodes are deployed in the macrocell which is called heterogeneous network (HetNet). The HeNB、pico cell、micro cell are in the coverage of MeNB and they are used to help improve the communication performance of the hotspot or the cell-edge users. Although the Flexible deployment can contribute to improve the capacity of the communication system, it makes the original network topology more complex and forms a variety of types of new interference environment.Physical downlink control channel(PDCCH) is a very important control channel which is used to transport downlink and part of the uplink control information. It is the key of the terminal control part and the precondition of the service communication and uplink synchronization between UE and the eNB. The cell-specific reference(CRS) signal which is usually broadcasted to all the users in the cell and it is very important for the downlink channel measurement and estimation. Physical Uplink Shared Channel(PUSCH) helps to transfer data and control information from high layer to physical layer. It plays a very important role for the heterogeneous network to optimize the interference of PDCCH、CRS、PUSCH, and so on. This paper proposes three new methods, the algorithm based on resource allocation and power control to reduce the interference of downlink common channel in HETNET system, the algorithm based on resource allocation and power control to reduce the interference of uplink shared channel in HETNET system and one interference elimination method based on blank subcarrier and the estimation of time offset and frequency offset. The contributions this paper has made are as follows:For the interference of downlink common channel in HETNET system, this paper has proposed an algorithm based on resource allocation and power control to reduce the interference. This algorithm prevents the occurrence of the phenomenon that the base station constantly increases the sending power to maintain the communication quality and reduce the interference based on reasonable allocation of downlink control channel resource and semi-static power control of CRS.As to the interference of uplink shared channel in HTENET system, this paper has presented an algorithm based on resource allocation and power control to reduce the interference of uplink shared channel in HETNET system. Using reasonable assignment of uplink channel resource and the power control of PUSCH can reduced the interference and BLER.Referencing to the interference of CRS between macro cell and micro cell in HETNET system, this paper proposed one interference elimination method based on blank subcarrier and the estimation of time offset and frequency offset. This method can reduce the interference of CRS in HETNET system and improve the system performance.