| The3rd Generation Partnership Project (3GPP) Long Term Evolution-Advanced (LTE-Advanced) is a technology of next generation mobile communication based on the LTE evolution. In order to enhance a higher data transfer rate to meet the growing needs of users for a variety of multimedia services, multi-antenna technology is introduced in the standards of3GPP LTE-Advanced. Compared to3G, LET-Advanced can provide higher data rate, better quality of service, higher spectral utilization ratio, better security, higher intelligence, better transmission quality and the higher the flexibility. The advantages we discussed above make the technology become the hotspot to research on the field of the next generation mobile communication. Since3GPP startup LTE project at the end of2004, OFDMA technology has been selected as the project’s option of downlink, and rapidly develop. But the SC-FDMA technology is designated as the project’s option of uplink in a much late time, whose peak-to-average ratio is lower than OFDMA technology. Therefore, the maturity of the development of SC-FDMA technology is far less than That of OFDMA technology. In recent years, SC-FDMA technology is continuing developing due to the studies of many experts and scholars. MIMO technology appears earlier than SC-FDMA technology, but the combination of the two technologies is introduced in the uplink option of Release10. In this paper, we mainly study the timing synchronization algorithm for MIMO SC-FDMA System in uplink of LTE-Advanced.First of all, a brief introduction of the related knowledge about LTE-Advanced is made in this paper. The mathematical model and technical characteristics of the MIMO SC-FDMA system in uplink scheme of LTE-Advanced are analyzed. Also several MIMO detection algorithms, which are commonly used, are introduced, such as maximum likelihood detection algorithm, linear detection algorithm based on different criteria. Then the analysis and discussion on the impact of timing offset in MIMO SC-FDMA system are made, and a review about the situation of the current domestic and foreign scholars study for LTE-Advanced uplink MIMO SC-FDMA system on timing synchronization algorithm is summarized. In traditional part, coarse estimation and fine estimated is made in most of the timing synchronization algorithm. Then the starting location of the FFT detection window is determined, so as to achieve the purpose of perfect symbol timing synchronization at the receiver.In this paper, serial interference cancellation technique of MIMO detection algorithm is applied to eliminate the interference between multi-antennas, brought about by the timing offset in the MIMO SC-FDMA system. In the proposed algorithm, the timing offset is not estimated, but to regard the impact of timing offset as the interference which can be estimated and eliminated, and to eliminate the interference in the signal detection process. An interference cancellation of timing synchronization algorithm for single-user MIMO SC-FDMA system is proposed in this paper, in order to improve the impact about multi-antenna interference, brought about by the small value of timing offset. The idea of cyclic iteration is used in the algorithm. In order to achieve cancelling the interference, signal to be detected should be sorted according to the maximum output signal-to-noise ratio first. Secondly, symbols are detected successively. Then the interferences caused by the already detected symbols are subtracted from the total received signal. The theory analysis and the simulation results show that the algorithm can improve the BER performance of the SU-MIMO SC-FDMA system. |
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