The Research Of SRS Signal Detection Techniques For LTE/LTE-A System

With the rapid development of mobile Internet technology, the public has put forward higher requirements for mobile communications. In order to bring a faster peak rate, higher resource utilization and lower transmission delay, the fourth-generation mobile communication technology(LTE/LTE-A) based OFDM(Orthogonal Frequency Division Multiplexing) technology was born. By defining SRS(Sounding Reference Signal),LTE/LTE-A system detects the uplink channel quality information, and then reports to the resource scheduler as the main basis for the uplink scheduling, so as to achieve the uplink frequency domain resource selective scheduling effectively and improve the throughput of the whole system. How to accurately reflect the uplink channel quality information is the key to improve spectrum efficiency and enhance the system throughput. Therefore, the main work on the basis of studying SRS detection technology is as follows:(1) In-depth analysis of the 3GPP TS36(R9) serial protocol SRS about SRS generation, including the SRS frame structure characteristics, the base sequence generation, SRS group hopping and sequence hopping, SRS subframe configuration and multi-user configuration problems; Study the SRS transmitter and receiver basic flow.(2) On the basis of the existing research SRS noise estimation algorithm, existing algorithms can't accurately estimate the user each RB(resources) on the problem of channel quality information, so this thesis proposes a Discrete Fourier Transform(DFT) time-domain filtering algorithm based on interference cancellation. The algorithm uses the idea of interference cancellation. After each UE(User Equipment) signal is detected, the data of the UE will be removed in the receiving end. When all users are detected, the resulting signals are considered as interference and noise. At the same time, by calculating signal power in the system protecting band, decision threshold of time domain filtering can be denoted. Therefore, one can reduce the impact of noise on the useful signal within the window, and also obtain more accurate noise estimation. Simulation results show that either in the case of single-user or multi-user, the proposed algorithm can accurately estimate the channel quality information. Meanwhile, the algorithm can accurately reflect the impact in neighborhood interference on each band channel quality, so as to achieve the frequency domain resource selective scheduling effectively.(3) SRS timing estimation accuracy is very important for base station uplink synchronization control in LTE/LTE-A. Existing algorithms estimation error is large in the case of channel quality is poorer. Using the phase difference method, this paper proposed an improved window length estimation method. The simulation results show that the improved algorithm can get better time offset estimation.(4) Taking into account the influence of power and hardware costs for engineering applications. Fix the SRS receiving terminal on the basis of the designing and building the SRS link as the basis of the SRS channel hardware implementation. At the same time the simulation results verify the accuracy of fixed point by comparing with the float.