Digital Self-interference Cancellation Technology Of 2×2 LTE Full-duplex System

Co-Frequency Co-Time full duplex is different from the time-division duplex and the frequency-division duplex in wireless communication, it does not rely on the different time slot or frequency band to distinguish data, effectively avoiding the waste of spectrum resources. However in Co-Frequency Co-Time full duplex communication system, as the sending and receiving equipment work at the same frequency band and the same time slot, the useful signal would be interfered by the local transmission signal, namely a strong self-interference signal.Currently, the existing self-interference cancellation technology can be divided into three kinds: antenna interference cancellation, RF interference cancellation and digital interference cancellation. The digital interference cancellation technology is an important research direction. In this thesis, we centered the digital self-interference cancellation method based on 2 ?2 LTE full-duplex system, details are as follows:Firstly, we selected the way of rebuild self-interference signal as the method applied in 2 ?2 LTE full-duplex system. Then made a special design for the LTE system pilot structure; we had algorithm derivation and performance simulation about the digital self-interference cancellation method; Following conclusions can be obtained from the simulation: in Rice channel, when INR equals 32 dB, the ability of digital interference cancellation can achieve 29.8dB; and it had about 2dB performance loss to full-duplex system.Secondly, we analyzed the effect of sampling frequency offset to the method. Then designed a closed-loop searching control method to the crystal. Following conclusions can be obtained from the simulation: when SNR equals 10 dB, the ISR equals 20 dB, symbol timing errors equals 12 symbols, it has about 3dB performance loss compared to the perfect result.Finally, we had a top-level logic design about the digital self-interference cancellation technology, which including the top-level design, internal structure, work process and so on. We also had a function test about technology on the hardware platform, and conducted performance tests under different scenarios. The results showed that the control method is effective and the cancellation had about 1.5dB performance loss compared to the simulation result.In this thesis, the digital self-interference cancellation technology is designed which can be applied to a 2 ?2 LTE full-duplex system and provide theoretical and engineering reference to the further exploration.