A scheme of combining DFO and channel estimation scheme for mobile OFDM systems

To reduce the impact of residual Doppler frequency offset (RDFO), a joint DFO estimation and CE scheme is proposed for the OFDM systems under the high-speed mobile environment. In the paper, the expression of interference power caused by the RDFO is first derived, and the effect of RDFO on time-varying characteristic of channel is analysed. Then, a joint DFO and channel estimation scheme is presented. Specifically, a high-precision DFO estimator based on the convolutional neural network with anti-noise is firstly designed. Due to its ability to use fewer samples to adapt well to the new environments, the meta learning is adopted to estimate the time-varying channel. Moreover, to improve the practicality of the algorithm, the non-ideal values rather than ideal values are used as the training targets in the two neural networks. Additionally, the proposed method is only based on the received signal and does not require any pilots or training sequences, which has higher transmission efficiency compared to the existing algorithms. The research results indicate that the proposed method has good estimation performance and good practicality, and it is suitable for high-speed mobile scenarios.