Iterative (Turbo) equalization for doubly-selective channels using exponential basis expansion models

We present an adaptive soft-input soft-output (SISO) turbo equalization receiver for doubly-selective channels. The proposed receiver exploits the complex exponential basis expansion model (CE-BEM) for the overall channel variations, and an autoregressive (AR) model for the BEM coefficients. We extend an existing turbo equalization approach based on symbol-wise AR modeling of channels to channels based on BEMs. Simulation examples and an EXIT chart analysis demonstrate that our CE-BEM-based approach outperforms the existing symbol-wise AR model-based turbo equalizer.