Design And Implementation Of Digital Self-interference Cancellation In Single Channel Full-duplex Communication System Based On FPGA

How to further improve the utilization of the limited radio spectrum has been the research focus in the field of wireless communications. Researchers have been working on a lot of new techniques and algorithms to make full use of the radio spectrum resources. In this thesis, the technology of single channel full-duplex wireless communication can achieve sending and receiving at one time slot by the same frequency channel, which further doubles the system effective throughput in theory. However, as a developing new technology, single channel full-duplex wireless communication technology is facing a lot of problems. In single channel full-duplex wireless communication system, the receiver of a node will not only receive the useful signal from the remote node, but also receive the signal from the node itself at the same time. The signal from the node itself can interfere the receiver of the node itself to receive the useful signal from the remote node. The loss power of the useful signal from the remote node is very large because of a long transmission. So the power of the useful signal is far less than the interference signal’s power at the node receiver. When the Mixed-Signal (including the useful signal and the interference signal) go through ADC, the interference signal will occupy most of the dynamic range of ADC. The useful signal from the remote node will be completely submerged in the interference signal. So the receiver can not correctly decode the useful signal. In order to achieve single channel full-duplex wireless communication, eliminating self-interference signal as much as possible is required. This is also the main direction of the researchers in this technical field in recent years.In this thesis, we studys the development of self-interference cancellation technology and focuse on adaptive digital self-interference cancellation technology based on the channel estimation. We have built a digital baseband communication system to achieve self-interference cancellation technology based on LMS adaptive filter. We study the design principles of digital receivers and transmitters. We introduces the implementation of square root raised cosine filter, symbol synchronization, LMS algorithm, channel estimation, frame synchronization, and digital self-interference cancellation. At the same time the thesis gives the implementation of the carrier synchronization loop. An overall design scheme of single channel full-duplex wireless communication system based on self-interference cancellation technology having adaptive Channel Estimation is proposed. And an analysis for the scheme is given.