Digital Harmonic Interference Cancellation between LTE and 5G NR in Terminal

As a typical heterogeneous network, the fifth generation (5G) mobile communication system must be compatible with existing technologies (such as Long-Term Evolution (LTE)) and support multiple types of 5G New Radio (5G NR). When multiple air interface technologies coexist, mutual interference will inevitably occur between different working frequency bands (for the same device, we call this interference “self-interference (SI)”). In this paper, for the typical SI of harmonic interference, we propose a new digital-domain interference cancellation method, which can be widely applied to 5G mobile communication systems. By making Band3 (B3) and New Radio78 (n78) work simultaneously, the proposed new method can eliminate the 2nd harmonic generated by the power amplifier (PA) in n78's receiving link. Furthermore, in order to improve the accuracy of nonlinear harmonic components in wideband systems, an equivalent frequency-domain analysis model of harmonic signals is established, following which an iterative channel estimation technique can be employed for improving the accuracy of the proposed scheme. Numerical results demonstrate that the proposed scheme is capable of achieving a high-precision harmonic SI cancellation.