Research On Key Technology Of Uplink Multiple Access Scheme In LTE

With the gradual worldwide deployment of third generation (3G) services,3GPP initiates new projects such as Long Term Evolution (LTE) standard in response to customer demands for data services and challenges of other standards. The current LTE standard has been basically completed and put into applications. While during the standardization process, various uplink and downlink multiple access schemes were proposed, eventually single-carrier frequency-division multiple-access (SC-FDMA) and orthogonal frequency-division multiple-access (OFDMA) are accepted as the uplink and downlink multiple access schemes respectively.As the combination of single-carrier frequency-domain-equalization (SC-FDE) technique and discrete Fourier transform (DFT) proceeding technique, SC-FDMA can not only deal with the frequency selective fading channel but also achieve a lower peak-to-average power ratio (PAPR) than OFDM. The main objective of the thesis is to provide simulation researches on key technologies of SC-FDMA, with the emphasis on the subcarrier mapping.Aiming at the multiple access technology in LTE uplink transmission, the thesis starts with the basis introduction to the background, main performance targets and the determination of multiple access schemes in downlink and uplink of LTE. Then basic principles in SC-FDMA and other multiple access schemes including SC-FDE, OFDM with PAPR reduction, and interleaved FDMA (IFDMA) are provided. In the third section, the thesis describes a variety of frequency domain equalization methods, on the basis of which, the symbol error rate (SER) performance of the SC-FDE and OFDM technology are simulated and evaluated for different guard interval lengths. In the fourth part, comprehensive summary of SC-FDMA is presented, which involves the basis concepts, developing status, theoretical algorithms, as well as the open issues. Further, the SC-FDMA signal model is analyzed and the influences on PAPR SER performance exerted by SC-FDMA subcarrier mapping are evaluated through simulation. Finally, the performances comparisons between SC-FDMA and OFDM in different channel environments are provided.