What is BEM (Basis expansion model)?

The utilization of the basis expansion model for channel assessment is proposed for orthogonal frequency division multiple access (OFDMA) system uplink. The Basis Expansion Model (BEM) is used in a high-speed railway communication scenario for a fast time-varying channel. The channel impulse response is modeled as the sum of basis functions multiplied by various coefficients. Simulation results show that a Generalized Complex-Exponential BEM outperforms a Complex-Exponential. And BEM (CE-BEM) and a polynomial BEM in terms of Mean Squared Error (MSE). The MSE of the CEBEM diminishes as the number of basis functions increases.