This project falls within the research area of cellular networks, where Integrated Sensing and Communication (ISAC) is emerging as a key paradigm. Integrating communication and sensing within a single system presents several engineering challenges, particularly in resource sharing and adapting communication hardware and software for sensing. This thesis investigates how passive-target sensing can be integrated into a communication-centric system through the development of an experimental testbed. The testbed is implemented using N320 USRPs and a modified version of OpenAirInterface, realizing a monostatic sensing system with ensured time and phase synchronization. Channel State Information (CSI), obtained through channel estimation of Positioning Reference Signal (PRS) pilots, are then used to reconstruct delay and Doppler information of reflectors.