The method involves carrying out an equalization of a zero-forcing decision feedback equalizer (ZF-DFE) of received signal in a layer to count pulse position modulation and pulse amplitude modulation (PPM-PAM) symbols estimated in previous layers. The symbols realizing a lowest contribution is selected, and the contribution is added to obtain sum of contributions. The equalization of equalizer, selection of symbols and adding contribution are repeated till reaching a lowest layer. Quadratic radius of a sphere and a nearest point are updated, when the contributions sum is less than the radius. An independent claim is also included for a maximum-likelihood (ML) receiver for receiving pulse position modulation (PPM) symbols of a pulse type ultra wide band multiple-input and multiple-output (MIMO) system.
Maximium-Likelihood decoder for a multi-user system using pulse position and amplitude modulation