Interference Alignment Technology Based On The TD-LTE System And Its Implementation In FPGA

With the demand of users business arising, the contradiction between the communication requirements of high-rate-large-capacity and limited bandwidth resources push forward its communication concept and techniques. The appearance of MIMO-OFDM technology provides a new way to solve the contradiction. The domestic large-scale commercial use of TD-LTE system which downlink on the use of MIMO-OFDM technique results in a significant improvement of the communication rate and the system capacity. However, for the frequency reuse factor the net tends to 1, the problem of co-channel interference in intra-cell and inter-cell has become an important challenge to ensure the communication quality, rate and system capacity. The TD-LTE system of the users in an area affected by the interference from the co-channel relay nodes in a co-channel interference area and the cell edge users affected by other neighbor frequency cell base station. According to the interference problems and based on some comparison of the existing processing methods in these scenarios, we adopts interference alignment technique in this paper, built a platform to validate its model which based on the Xilinx FPGA ML605, and study the impact of this algorithm on system performance improvement. The main work in this paper is as follows:1. Through analysis of a typical interference scenarios in TD-LTE system, we design an interference alignment algorithm which based on some related theory knowledge make it is easy realized on FPGA system to improve the communication quality and system capacity. Comparing with MIMO-OFDM channel, the numerical simulation results will prove the more gain we get in bit error rate and capacity.2. Built a platform to validate the interference alignment model which based on the Xilinx FPGA ML605, optimize the computation of pre-coding matrix V and decoding matrix U, and solve the problem of too large consumption of resource because of high complexity and too long delay in system through simplifying the FPGA matrix inversion and multiplication algorithm.3. A method to solve the data to be transmitted over lager PAPR after pre-coding is proposed in this paper. Through these two ways of the LCD screen plate display and observation of PC constellation, we can prove the effect of the interference alignment algorithm. The test shows that application of interference alignment algorithm can improve the performance of the TD-LTE system.4. In order to verify the performance of Interference alignment under realistic wireless communication channels, we developed RF(Radio Frequency) System based on previous work. A LTE downlink MIMO-OFDM system was establish by μSDR420 software radio platform, which provide a basic condition for verifying the performance of Interference alignment under realistic wireless communication channels.The studies in this paper provides a feasible scheme to achieve the advantage of the interference alignment algorithm, supply with a reference to face the future mobile communication evolution, propose a solution to the interference in TD-LTE system.