Research On Precoding Technology For Imaginary Interference Elimination In MIMO-OQAM/OFDM System

In recent years,with the explosion of big data and the Internet of Things,e.g.,high-quality multimedia services,necessitate the evolution of efficient multicasting or broadcasting technologies.Due to high out-of-band leakage and low spectrum efficiency,the orthogonal frequency division multiplexing(OFDM)technology has been difficult to meet the needs of these new scenarios.In order to solve the shortcomings of OFDM technology,the offset quadrature amplitude modulation based orthogonal frequency division multiplexing(OQAM/OFDM)technology has been attracting increasing attentions.The OQAM/OFDM system has much lower out-of-band leakages since the usage of a well-localized pulse shaping filter.In addition,it has higher throughput efficiency because it does not require the cyclic prefix(CP).Therefore,OQAM/OFDM technology has become one of the physical layer alternative technologies for future wireless communication systems.In addition,multiple-input multiple-output(MIMO)precoding technology can greatly improve the performance of the communication system and increase the channel capacity,which has always been a research hotspot in the industry and academia.However,the inherent imaginary interference in OQAM/OFDM makes it difficult to directly integrate MIMO precoding technology.Therefore,this paper aims to study the precoding technology of imaginary part interference cancellation in OQAM/OFDM system without affecting the performance of spectrum efficiency.In this thesis,based on the classic OQAM/OFDM system model,the symmetry of imaginary interference factor are firstly analyzed.Then,based on the symmetrical nature of the imaginary interference,adopting the repeated data frame transmission structure,the interference elimination SVD precoding scheme is proposed.Finally,in view of the complexity and huge overhead of SVD technology,the paper adopts codebook-based precoding technology to reduce feedback overhead,and designs a MIMO-OQAM/OFDM codebook precoding scheme for imaginary interference cancellation.Furthermore,a limited feedback compression precoding scheme for interference cancellation is proposed,which use the frequency domain correlation of adjacent channels to divide subbands,and precoding is performed with the granularity of wordbands.The simulation results show that the proposed scheme can reduce the feedback overhead without bringing in performance loss.In conclusion,this thesis aims at the problem of combining OQAM/OFDM and MIMO precoding technology caused by imaginary interference,then designs a transmission scheme based on repeated data frame structure,which effectively eliminates symbols without sacrificing spectrum efficiency and transmission efficiency.The inter-imaginary interference improves the data transmission reliability of MIMO-OQAM/OFDM,and promotes the combination of OQAM/OFDM and MIMO precoding technology.