The emerging orthogonal time frequency space (OTFS) modulation is demonstrated to offer reliable communication performance advantages over orthogonal frequency division multiplexing (OFDM) in doubly-dispersive fading channel. However, the existing embedded pilot-aided method to estimate channel impulse response (CIR) requires enormous spectral overhead to avoid the contamination of pilot symbols. In this paper, we present a variational autoencoder (VAE) based receiver for OTFS modulation that achieve a joint estimation and detection without pilot in delay-Doppler (DD) domain. The variational approach is considered to simplify the problem, and evidence lower bound (ELBO) is derived as loss function. In encoder step, an approximate posterior probability is introduced and utilized to minimize the Kullback-Leibler (KL) distance. Then we estimate CIR in decoder step and maximize the ELBO at last. From our simulation results, the proposed VAE based receiver for OTFS modulation enjoys a promising performance with other methods.

新兴的正交时频空间 (OTFS) 调制被证明可以在双色散衰落信道中提供优于正交频分复用 (OFDM) 的可靠通信性能优势。然而，现有的用于估计信道脉冲响应（CIR）的嵌入式导频辅助方法需要巨大的频谱开销来避免导频符号的污染。在本文中，我们提出了一种用于 OTFS 调制的基于变分自编码器 (VAE) 的接收器，它在延迟多普勒 (DD) 域中实现了无导频的联合估计和检测。考虑变分方法来简化问题，并导出证据下界（ELBO）作为损失函数。在编码器步骤中，引入并利用近似后验概率来最小化 Kullback-Leibler (KL) 距离。然后我们在解码器步骤中估计 CIR，最后最大化 ELBO。从我们的仿真结果来看，所提出的基于 VAE 的 OTFS 调制接收器与其他方法相比具有良好的性能。