Research And FPGA Implement On WCDMA Digital Repeater

In WCDMA system, the repeater is a kind of optimal scheme to outspread the communication network coverage ability, which can guarantee the network coverage quality without increasing the number of the base station. The basic function of the repeater is to increase the power of the RF signal, which mainly completes the task of relaying and the transmitting the wireless signals between the base station and terminal. But, due to the receiving and transmitting antenna isolate degree is not enough, the traditional RF repeater is prone to cause self-excitation, which leads to output high power stray signals, obstruct the entire bandwidth, seriously impacts on the application of repeaters.Firstly, the research background and significance of the digital intermediate frequency of WCDMA repeater is introduced in this thesis. Secondly, the theoretical basis of the intermediate frequency is analyzed, including the NCO, the digital orthogonal frequency mixing, the CIC and FIR extraction and interpolator filter, etc. Then, the principle of adaptive interference cancellation is studied, and the algorithm performance of the adaptive interference cancellation is analyzed. On this basis, the basic adaptive interference cancellation algorithm is applied in the digital intermediate frequency of the WCDMA repeater. Finally, the design of the digital intermediate frequency system is implemented on FPGA, the intermediate frequency system with and without the adaptive interference cancellation is being simulated. The simulation result shows that the interference problem of the traditional repeater is effectively solved with joining the adaptive interference cancellation device.