Precoding Technology Based On Correlation Rotation For Generalized Frequency Division Multiplexing System

Generalized Frequency Division Multiplexing(GFDM)technology is a new multicarrier transmission technology which is proposed to cope with the high standard of the 5th Generation mobile communication.GFDM system uses a technology of non-rectangular pulse shaping and has the advantages of low out-of-band,high spectrum efficiency and good flexibility.But its special structure of system results in a non-orthogonality between subcarriers.So there is self-interference and the reliability of the system becomes low.This thesis aims at studying the technology for eliminating interference and designing a precoding method to solve the problem.The main contributions of this thesis are following:1.The principle and feature of GFDM system are studied and analyzed deeply.The system models are set up and the main performance is evaluated via simulations.2.A precoding method based on correlation rotation for GFDM system is proposed.This method need not to eliminate the interference completely.It converts the interference to gain factor of symbol for using it by a phase rotation of interference.Then a power allocation method based on symbol error rate optimization is proposed to solve the problem of poor reliability caused by frequency selective fading.The analysis and simulations demonstrate that the two methods proposed can greatly eliminate the influence of interference and improve the reliability of system.3.In order to solve the problem of high complexity of correlation rotation precoding for GFDM,the characteristics of equivalent channel are analyzed and its internal sparsity is found.Thus an equivalent frequency-domain channel model is set up and a correlation rotation precoding method with low complexity is designed.This method makes use of sparse matrix multiplication and fast algorithms for inverting block periodic tridiagonal matrices to reduce the complexity of precoding.The analysis of complexity and simulations of symbol error rate demonstrate that this method can greatly reduce the complexity of precoding and improve the reliability of system further.4.The system model of MIMO-GFDM is analyzed deeply.Because there is interference between antennas,multipath fading and self-interference,a channel equalization method, a correlation rotation precoding method and a power distribution method are proposed to eliminate all kinds of interference.The analysis and simulations demonstrate that the methods proposed can greatly eliminate interference and obtain a good reliability.GFDM system and MIMO system can be combined effectively.