Research On The Universal Filtered Multicarrier And Its Transmission Performance Under Imperfect Synchronization Conditions

With the rapid development of mobile communication technology,the 5G for 2020 and future has become the current research hotspot.In the next few years,verious new businesses will increase fast,and the internet of things(Io T)will expand explosively.Due to the drawbacks of large sidelobe leakage and sensitivit y to synchronization errors,OFDM is hard to meet the needs of Io T in 5G,such like fragmented spectrum utilization,transceiver with frequency and time offset as well as multiuser asynchronous transmission.In this thesis,the last two characteristics of Io T are called transmissions under imperfect synchronization conditions.Among many new waveform candidates for 5G,the universal filtered multicarrier(UFMC)technology can effectively reduce the sidelobe leakage.At the same time,it has high flexibility and low computational complexity,and it's suitable for short packet data transmission.Therefore,many scholars consider it a very competitive new waveform solution.However,UFMC technology is still in the exploration and optimization stage,especially the research with regard to its transmission performance under imperfect synchronization conditions.Firstly,this thesis introduces the research backgroud of the topic and the state of art of UFMC technology.The rationale of UFMC is expounded and studied in detail,including the time-frequency characteristic of the signal and filter parameter influence of the system,which lays a good foundation for further research.Then,the UFMC performance is researched under the conditions of synchronization.For UFMC,the noise on the subcarriers at the edge of each subband will be amplified during filter compensation process at the the receiver,so that the bit error rate(BER)performance degrades.This thesis proposes two precoding schemes,i.e.DFT and WFRFT precoding,to reduce the degradation.At the same time,the analytical BER expressions of the original UFMC and its two precoding schemes over the AWGN and frequency-selective fading channels are derived and verified by the simulations.Performances of the three schemes,such as BER,peak to average power ratio(PAPR)and out of band power(Oo BP),are analyzed and compared.Facing of transmission requirements of Io T application scenarioes under imperfect synchronous conditions in 5G,the deep and comprehensive research on the performance of UFMC technology and its precoding schemes under asynchronous transmission is divided into “single-user transceiver asynchronization” and “multi-user asynchronous transmission” two scenarios,with the comparison of OFDM and its precoding schemes.The asynchronous conditions include three cases: the carrier frequency offset(CFO)or the time offset(TO)only,and joint existence of CFO and TO.Simulations are conducted over AWGN and frequency-selective fading channels under different scenario es and conditions.The research results provide a certain reference for the performance evaluation of U FMC technology as well as the design and selection of new waveforms.