Fast Noncoherent Decoding of Block Transmissions over Doubly Dispersive Channels

We propose a scheme for noncoherent iterative (i.e., turbo) reception of coded block transmissions over unknown time and frequency selective, or doubly dispersive, channels. Starting with a noncoherent metric that leverages a basis expansion model (BEM) for the channel´s time-variation, we propose an efficient noncoherent soft equalization strategy that combines sub-optimal tree search with a fast noncoherent metric update. Though the complexity of our scheme is only linear in the block length and quadratic in the number of BEM parameters, numerical experiments show that it attains a performance relatively close to that of the turbo receiver with perfectly known channel.