What is SRN (secondary reference node)

In the realm of wireless communication networks, particularly GSM (Global System for Mobile Communications), SRN stands for Secondary Reference Node. It plays a vital role in the synchronization process within the network, ensuring accurate timing and data transmission among various network elements.

Primary Reference Node (PRN):

Before delving into the specifics of SRN, it's essential to understand the role of the Primary Reference Node (PRN). The PRN is the central source responsible for generating precise timing signals within the network. These timing signals are critical for various network functions, including:

• Frame Synchronization: Ensuring all network elements are operating on the same timing frame for data transmission and reception.
• Handoff: Facilitating seamless handoff of ongoing calls between different cell towers as a mobile user moves around the network coverage area.
• Channel Timing Adjustment: Enabling proper time alignment for signals transmitted on different radio channels within the network.

SRN as a Synchronization Backup:

The SRN serves as a secondary source of timing information within the network. Its primary function is to provide redundancy and backup to the PRN in case of a failure. Here's a breakdown of how SRN contributes to network synchronization:

1. Synchronized with PRN: The SRN itself receives the precise timing signals from the PRN and maintains its own internal clock synchronized with the network timing reference.
2. Local Backup Source: If the primary source (PRN) fails, the network can rely on the SRN to continue providing timing information to other network elements within its designated geographical area.
3. Limited Functionality: While SRN offers redundancy, its functionality might be limited compared to the PRN. The specific capabilities of an SRN can vary depending on the network implementation. Some SRNs might simply retransmit the received timing signal from the PRN, while others might have the ability to generate a backup timing signal for a limited period.
4. Network Architecture: The exact location and deployment strategy for SRNs within a network can vary depending on the specific network architecture and operator configuration.

Benefits of SRN:

• Enhanced Network Resilience: The presence of SRN provides a crucial layer of redundancy for network synchronization. In case of a PRN failure, the network can continue functioning with minimal disruption.
• Improved Network Availability: By ensuring accurate timing even during PRN outages, SRN helps maintain network availability for voice and data services.
• Reduced Call Drops: Proper synchronization is essential for seamless handoffs. SRN helps mitigate call drops that might occur due to timing inconsistencies during handoff procedures.

Additional Notes:

• The specific details regarding the capabilities and implementation of SRNs can vary depending on the network equipment vendor and the specific version of the GSM standard being used.
• Security measures are in place to ensure the authenticity and integrity of the timing signals distributed by both the PRN and SRN.

I hope this explanation clarifies the technical aspects of SRN (Secondary Reference Node) and its role in maintaining network synchronization within GSM networks.