Supersonic shock-wave/boundary-layer interactions (SWBLI) can be observed around the control surfaces of an aircraft and inside the supersonic inlets. The SWBLI results in a separated flow, which is characterized by large amplitude but low frequency unsteadiness. The aim of the research in this area is to understand the source of the instability and its driving mechanism(s). This paper investigates the SWBLI in a generic case of a Mach 1.6 supersonic flow over a flat plate where a sonic circular jet is transversely injected. The research presented in this work utilizes a Finite Volume approach to solve the Navier-Stokes equations on a structured grid using high-resolution methods in the framework of implicit large eddy simulations (ILES). The supersonic turbulent boundary layer over the flatplate is generated using a digital-filters-based technique. The unsteadiness in the upstream turbulent boundary layer and the downstream flow field instabilities are analyzed for the low frequency unsteadiness and pulsations in the upstream separation zone with a view to understand their driving mechanism in such a complex flow situation.