Research Of Interference Elimination Method In Heterogeneous Networks

In the fourth generation communication LTE-A standard, it uses a series of techniques to improve the wireless communication system performance, such as the peak data rate, the system spectral efficiency and the user service quality of cell-edge. It can improve the system performance when taking the different types of low-power nodes into the heterogeneous network, however the low-power nodes will make interference that in the heterogeneous more complex. The existed interference coordinated technology has not solve this kind problems, when apply the coordinated multipoint transmission(CoMP) technology to the heterogeneous network, it can eliminate the inter-cell interference through the base stations collaboration, then improve the system energy efficiency and the service quality of cell edge users.First, this article describes the system architecture and the key technologies of LTE-A, and analysis the new interference aroused by the low-power nodes. In order to reduce the inter-cell interference in the heterogeneous scenarios, it will use the CoMP technology. When the mobile terminals configure multiple received antennas, this paper design a block diagonalization(BD) algorithm which can eliminate the interference after analyzing system beamforming, so it increases the throughput of the network and improves the system energy efficiency. Defines a performance metric, and turn it into a convex optimization problem to determine the factors that affect the energy efficiency performance of heterogeneous networks. The simulation proved that the proposed method compared to conventional zero-forcing algorithm can significantly improve the throughput and efficiency of the system.Coordinated multi-point(CoMP) transmission technology can effectively eliminate the interference of multiple networks in heterogeneous networks, but the channel acquisition of network users will be influenced by transmission delay and quantization errors, and the interference cancellation effect change to bad. When the end user configures multiple antennas, the performance loss is not clear. For this problem, the throughput loss caused by this two kinds of negative factors was analyzed, and obtained the theoretical throughput loss upper bound, the simulations verified the correctness of the theory.Because of the overhead delay in backhaul link, the channel estimation error and quantization error, there exist bias of the designed beamforming and the interference cancelation effect be affected. At the last, according to the channel estimation error, quantization error and overhead delay between base stations, this paper design a transceiver combined interference cancellation robust beamforming algorithm. Simulation results show that when compared to the traditional block diagonalization beamforming, the proposed algorithm can eliminate the inter-cell interference better, and the system throughput and bit error rate can improved significantly.