A new extended modeling of Lower Hybrid Current Drive (LHCD) is presented. The model incorporates Parametric Instabilities (PI) of launched LH waves into a ray-tracing + Fokker Plank code providing robust and accurate simulations of the LH-driven current density profiles. The new approach is tested on the interpretation of the long lasting Internal Transport Barriers (ITBs) of Joint European Torus (JET). The implementation of the results from the extended LHCD model in a transport code allows the simulation of the q-profile evolution in agreement with that provided by the Motional Stark Effect (MSE) reconstructed equilibria. Low magnetic shear (s 0) is produced by LHCD in a layer close to the ITB radial foot.