Research On Timing Synchronization Technology For MIMO SC-FDMA System In LTE-Advanced Uplink Based On Eliminating Interference

LTE-Advanced is the fourth generation mobile broadband standard, is developed by the Third Generation Partnership Project (3GPP) organization based LTE technology. LTE-Advanced uplink is using a single carrier frequency division multiple access techniques SC-FDMA technology, SC-FDMA technology with two advantages,low peak to average power ratio of the single-carrier (PAPR) and high toughness of multi-carrier. In addition, LTE-Advanced introduces single-user multi-antenna technology (SU-MIMO), the use of MIMO technology to achieve spatial diversity, improve wireless channel capacity, raising the spectrum utilization without increasing the bandwidth and antennas transmit power.MIMO SC-FDMA technique is very sensitive to synchronization error including timing offset and frequency offset, it requires precise timing synchronization to protect the symbol frequency conversion when the alignment. Time out of step can cause inter-symbol interference (ISI), effect of subcarriers orthogonal leading to inter-carrier interference (ICI), seriously affect system performance. Therefore paper studies the MIMO SC-FDMA system timing synchronization.Interference cancellation algorithm derived from the CDMA multi-user detection technology is to solve the MAI due to non-orthogonal spreading code sequence. The first detected data is restored to interference, and then eliminated to improve detection performance back data stream. The interference of CDMA Systems MAI and MIMO SC-FDMA system interfere timing deviation has great similarities. They are, in essence, system interference system interference caused by non-orthogonal properties. In view of the mathematical model for wireless MIMO transmission link with CDMA systems and ISI channel have similarities, while conventional interference cancellation algorithm is widely used in CDMA multiuser detection algorithm, the paper studies the timing synchronization algorithms based on interference cancellation for LTE-Advanced uplink (MIMO SC-FDMA system) and proposed an improved timing synchronization algorithm based multi-stage iterative interference cancellation.First, the article outlines the development of key technologies and LTE-Advanced system status, describes the basic principles and system models of MIMO SC-FDMA system, and analyzes the wireless communication environment, the timing offsets principle models and the impact on system performance. Again, a simple analysis of the existing classical timing synchronization algorithm and timing synchronization algorithm based interference cancellation. On the basis of signal detection theory, an improved timing synchronization algorithm based multi-stage iterative interference cancellation, and the algorithm principle and model will be are given. Finally, this paper analyzed and compared the bit error rate performance of various algorithms by MATLAB simulation.The improved timing synchronization algorithm based multi-stage iterative interference cancellation without using the pilot and cyclic prefix timing synchronization information, Firstly, using the MMSE criterion estimates the received signal in signal detection signal, and detecting that signal using multilevel iterative interference cancellation algorithm to eliminate signal interference caused by Timing offset, then achieved the purpose of timing synchronization. Theoretical analysis and simulation results show that the timing synchronization algorithm based on multi-stage iterative interference cancellation can significantly improve system performance. Among them, the OSIC-PIC, the PIC-PIC method can obtain a bigger gain, better to eliminate the disturbance of the timing synchronization error.