Channel Estimation for Delay Alignment Modulation

Delay alignment modulation (DAM) is a promising technology to eliminate inter-symbol interference (ISI) without relying on sophisticated equalization or multi-carrier transmissions. The key ideas of DAM are delay pre-compensation 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 propose an efficient channel estimation method for DAM based on block orthogonal matching pursuit (BOMP) algorithm, by exploiting the block sparsity of the channel impulse response (CIR) vector. Based on the imperfectly estimated CSI, the delay pre-compensations and path-based beamforming are designed for DAM, and the resulting performance is studied. Simulation results demonstrate that with the proposed 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.