What is SRNS Serving Radio Network Subsystem

SRNS (Serving Radio Network Subsystem) Explained in Detail

Within the realm of UMTS (Universal Mobile Telecommunications System) networks, specifically WCDMA (Wideband Code Division Multiple Access), SRNS stands for Serving Radio Network Subsystem. It encompasses the network elements responsible for managing the radio interface and controlling user equipment (UE) within a specific coverage area.

Breakdown of SRNS:

The SRNS can be thought of as a subsystem within the UMTS network architecture, consisting of two key components:

1. UTRAN (UMTS Terrestrial Radio Access Network): This air interface manages the radio communication between the UE and the network. It includes elements like:
   • Node B (Base Station): These base stations transmit and receive radio signals to and from UEs within their coverage area.
   • Radio Resource Control (RRC): This protocol layer manages radio resources like channels, power levels, and handovers between Node Bs.
   • Medium Access Control (MAC): This layer controls access to the radio channel for UEs within a cell.
2. RNC (Radio Network Controller): This network element controls the radio resources within a specific area and manages communication with UEs. It performs tasks like:
   • Radio Resource Management (RRM): Assigning channels, power levels, and managing handovers for optimal network utilization.
   • Mobility Management (MM): Tracking UE location, registering UEs, and triggering handovers when a UE moves to a different coverage area.
   • Security: Implementing security measures like ciphering and authentication for user communication.
   • QoS Management (Quality of Service): Prioritizing resources to ensure desired service levels for different types of data traffic.
   • Control of Lower Layers: Controlling the RRC and MAC layers within the UTRAN protocol stack.

SRNS as a Functional Unit:

• The SRNS works as a cohesive unit to manage user equipment within a specific area. The Node B collects radio signals from the UE, forwards the information to the RNC, and executes commands from the RNC to control the radio link with the UE.
• The RNC utilizes the information from the UE and other network elements to make decisions about resource allocation, mobility management, and overall control of the radio interface for that specific coverage area.

Interaction with Other Network Elements:

• The SRNS interacts with the Core Network (CN) for tasks like call setup, data transfer, and user authentication.
• It also communicates with neighboring SRNSs (controlled by other RNCs) to facilitate handovers when a UE moves between coverage areas.

Benefits of SRNS:

• Efficient Radio Resource Management: The SRNS optimizes radio resource utilization within a coverage area, ensuring network capacity is used effectively.
• Seamless User Experience: By managing radio resources and mobility effectively, the SRNS contributes to a smooth user experience with minimal call drops or connection issues.
• Scalability: The distributed architecture of UMTS with SRNSs managing specific areas allows for network scalability as user demand increases.

Evolution to LTE and Beyond:

• With the introduction of LTE (Long Term Evolution) networks, the concept of SRNS has evolved. While the functionalities remain essential, the specific network elements involved have changed.
• In LTE, eNodeBs (evolved Node Bs) handle radio communication, and the MME (Mobility Management Entity) within the EPC (Evolved Packet Core) takes over the control functions previously performed by the RNC.

Additional Notes:

• The specific details regarding the SRNS's capabilities and implementation might vary depending on the specific version of the UMTS standard being used.
• Security measures are in place to ensure secure communication between the UE and the SRNS.