FBMC-based Massive Connectivity with Asynchronous Transmission and Frequency-selective Channels

In this paper, we study filter bank multi-carrier (FBMC)-based uplink massive connectivity systems with asynchronous transmission and frequency-selective channels. We focus on the joint active device detection, delay and channel estimation (JADDCE) problem as they are critical for subsequent decoding or other processes. The problem can be put into the compressed sensing (CS) framework, where the structural sparsity is explored, and an efficient algorithm is proposed for JADDCE. Besides, since parameters such as noise variance and activity probability may not be perfectly known by the receiver, we introduce the expectation maximization (EM) method into the algorithm and derive the updating rules of the unknown parameters. Simulation results show satisfying performance of the proposed algorithm under frequency-selective channels.