In this paper a 3D-deterministic channel model for UWB chipless RFID system is presented. The tag in this work will be modeled as a 3D object, with frequency dependent Radar Cross Section (RCS), embedded in the channel which has several incident and reflected multipath at various directions both from the reader-tag and the reader-reader environment effect. In this model all channel effects as multipath components, fading, frequency dependence, reflections, diffractions and polarization dependence will be considered. Moreover, a novel chipless RFID reader system model with Zero Forcing (ZF) based equalizer is proposed. The equalizer based system will increase the chipless tag identification distance by mitigating the aforementioned channel effect. The concept is tested using a deterministic channel from a ray-tracing model with a 8-bit frequency coded concept of a compact printable orientation independent chipless RFID tag. Furthermore, a 3D-Electromagnetic (EM) simulation tool is used to compute the Frequency Coding Response (FCR) and the RCS of the CFC-RFID tag. Simulation results show constructive guidelines for designing multi-tag UWB RFID communications and enhancing the channel estimation process of the chipless RFID tag systems.