Low Overhead Pilot Design for Channel Estimation in MIMO-OTFS Systems

In this paper, we study the pilot design for channel estimation in orthogonal time-frequency space based multiple-input multiple-output (MIMO-OTFS) systems. Firstly, we propose a low overhead pilot pattern, which is accurately designed according to the maximum Doppler and delay spread of the channel. Then, based on the proposed pilot pattern, the channel estimation and data detection are performed. For threshold-based channel estimation, an optimal threshold is determined by simulation. In addition, the bit error rate (BER) performance of the system is provided. It can be observed that the proposed pilot scheme can work well in both medium Doppler and high Doppler cases. The overhead of the proposed scheme is about 11% lower than that of the traditional pilot scheme, which thereby increases the data rate. Further, the impact of some key parameters on system performance is discussed. It is concluded that the performance of the channel estimation is robust to the data signal-to-noise ratio (SNR).