Delay alignment modulation (DAM) is a promising technology for inter-symbol interference (ISI)-free communication without relying on sophisticated channel equalization or multi-carrier transmissions. The key ideas of DAM are delay precompensation and path-based beamforming, so that the multi-path signal components will arrive at the receiver simultaneously and constructively, rather than causing the detrimental ISI. However, the practical implementation of DAM requires channel state information (CSI) at the transmitter side. Therefore, in this letter, we study an efficient channel estimation method for DAM based on block orthogonal matching pursuit (BOMP) algorithm, by exploiting the block sparsity of the channel vector. Based on the imperfectly estimated CSI, the delay pre-compensations and tap-based beamforming are designed for DAM, and the resulting performance is studied. Simulation results demonstrate that with the BOMP-based channel estimation method, the CSI can be effectively acquired with low training overhead, and the performance of DAM based on estimated CSI is comparable to the ideal case with perfect CSI.

翻译：时延对齐调制（DAM）是一种无需依赖复杂信道均衡或多载波传输即可实现无码间干扰（ISI）通信的 promising 技术。DAM 的核心思想是时延预补偿与基于路径的波束成形，使多径信号分量能同时且建设性地到达接收端，而非引发有害的 ISI。然而，DAM 的实际实现需要发射端具备信道状态信息（CSI）。因此，本文利用信道向量的块稀疏性，研究基于块正交匹配追踪（BOMP）算法的高效 DAM 信道估计方法。基于非理想估计的 CSI，针对 DAM 设计时延预补偿与抽头波束成形，并分析其性能。仿真结果表明，采用基于 BOMP 的信道估计方法能以较低训练开销有效获取 CSI，且基于估计 CSI 的 DAM 性能可与理想完美 CSI 情况相媲美。