A Radio Network Controller (RNC) is a key component in mobile telecommunications networks, particularly in UMTS (Universal Mobile Telecommunications System). It manages the radio resources and controls multiple Node B stations, which are the base stations that connect mobile devices to the network. The RNC ensures efficient communication by handling tasks such as call setup, handovers, and resource allocation. In addition to managing radio resources, the RNC also plays a crucial role in maintaining the quality of service for users. It monitors network performance and can adjust parameters to optimize connectivity. By coordinating between the core network and the radio access network, the RNC helps provide seamless mobile communication.