S RRC Secondary Radio Resource Control

Secondary Radio Resource Control (SRRC) is a component of the radio resource control (RRC) protocol used in cellular networks. The RRC protocol is responsible for managing the establishment, maintenance, and release of radio bearers between the User Equipment (UE) and the radio access network (RAN) in 3G, 4G, and 5G mobile networks.

The RRC protocol consists of three main states: the RRC idle state, the RRC connected state, and the RRC inactive state. The RRC connected state is further divided into two substates: the S-RRC (Signaling Radio Resource Control) and the D-RRC (Data Radio Resource Control) substates.

The S-RRC substate, also known as the secondary RRC substate, is responsible for managing the control plane signaling between the UE and the RAN. Control plane signaling refers to the exchange of signaling messages that carry important control information necessary for the operation of the network. These messages include network registration, handover signaling, and mobility-related procedures.

In the S-RRC substate, the UE is connected to the RAN, and it has an active RRC connection established for control plane signaling. The S-RRC substate is typically associated with low data transmission rates since it primarily handles control messages rather than user data. The primary purpose of the S-RRC substate is to ensure efficient and reliable signaling between the UE and the network.

During the S-RRC substate, the UE periodically exchanges control messages with the RAN to maintain the RRC connection and update its status. These messages include RRC connection setup, RRC connection re-establishment, and RRC connection release. The S-RRC substate also manages mobility-related procedures, such as handovers between base stations or cells, and performs necessary measurements and reporting for network optimization.

The S-RRC substate plays a crucial role in the overall performance and reliability of the cellular network. It ensures that the UE remains connected to the network and can efficiently communicate with the RAN for control purposes. The S-RRC substate helps in providing seamless mobility, efficient resource allocation, and effective management of signaling resources in the network.

It's important to note that the specifics of the S-RRC substate may vary slightly between different generations of cellular networks, such as 3G, 4G, and 5G. Each generation introduces new features and enhancements to the RRC protocol to meet the evolving requirements of mobile communication systems.