vSRVCC: How Single Radio Video Call Continuity Works in Mobile Networks

telcomatraining.com – In the ever-evolving landscape of mobile communication, ensuring seamless connectivity during voice and video calls is critical. One key technology enabling this continuity is vSRVCC (Video Single Radio Voice Call Continuity). This technology allows uninterrupted video calls when a user moves between LTE (4G) and legacy networks like 3G or 2G. In this article, we will explore how vSRVCC works, its benefits, and its role in modern mobile networks.

Understanding vSRVCC

vSRVCC is an enhancement of SRVCC (Single Radio Voice Call Continuity), which was initially designed for voice calls. While SRVCC ensures smooth transitions for voice calls from LTE to legacy networks, vSRVCC extends this functionality to video calls. It enables users to continue their video conversations without disruptions even when they leave LTE coverage.

This process is crucial in areas where LTE coverage is inconsistent or when a user moves into a region with only 3G or 2G network availability. Without vSRVCC, a video call would either drop or downgrade to an audio-only call, affecting user experience.

How vSRVCC Works

To understand vSRVCC, we need to break down its working mechanism into several key steps:

1. Call Establishment in LTE

When a user initiates a video call, it is set up over the LTE network using IMS (IP Multimedia Subsystem). IMS ensures that both voice and video components of the call are managed efficiently.

2. Detection of LTE Coverage Loss

As the user moves, the LTE network continuously monitors signal strength. If the system detects that the LTE signal is weakening and will soon be lost, it prepares for a handover to a legacy network.

3. Handover Decision and Preparation

The network makes a decision to transfer the ongoing video call to a 3G network using the Circuit-Switched (CS) domain. At this stage, both the voice and video components need to be seamlessly handed over. The MME (Mobility Management Entity) and the SRVCC-enabled MSC (Mobile Switching Center) coordinate the transition.

4. Seamless Call Continuity

During the handover, the IMS system ensures that the video session remains active by adapting the media parameters. Depending on the capabilities of the target network, the call may continue with both voice and video or transition to a voice-only call if video is not supported.

5. Completion of Handover

Once the transition is complete, the call continues without noticeable interruptions. The user can carry on with the conversation as the device now operates on the legacy network.

Key Benefits of vSRVCC

1. Uninterrupted Video Call Experience

vSRVCC enhances user experience by ensuring that video calls remain active even when moving out of LTE coverage areas.

2. Efficient Network Resource Utilization

By enabling seamless transitions between networks, vSRVCC optimizes the use of available network resources and prevents unnecessary call drops.

3. Better Quality of Service (QoS)

The technology ensures that users experience minimal degradation in call quality, particularly during mobility events.

4. Increased Adoption of IMS Services

As mobile operators transition to all-IP networks, vSRVCC supports the broader adoption of IMS-based communication services.

Challenges and Future of vSRVCC

Despite its benefits, vSRVCC faces challenges, including:

• Device and Network Compatibility: Not all mobile devices or networks support vSRVCC, limiting its widespread adoption.
• Latency Concerns: The handover process must be optimized to prevent delays that could impact user experience.
• Transition to 5G: With the emergence of 5G networks, operators are focusing on alternative technologies like VoNR (Voice over New Radio), which may eventually reduce reliance on vSRVCC.

As mobile technology continues to evolve, vSRVCC remains a critical component for ensuring seamless video communication in areas where LTE coverage is inconsistent. While its relevance may decline with full 5G adoption, its role in bridging the gap between LTE and legacy networks remains invaluable today.

Conclusion

vSRVCC is a vital technology for maintaining seamless video call continuity in mobile networks. By enabling smooth transitions from LTE to legacy networks, it enhances user experience, improves call quality, and ensures network efficiency. As 5G networks expand, vSRVCC will continue to play an essential role in ensuring uninterrupted video communication for mobile users worldwide.