Telecommunication

What is VANC Voice over Long Term Evolution via Generic Access Network Controller

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VANC: Bridging the Gap for Voice over LTE

VANC, or Voice over Long Term Evolution via Generic Access Network Controller, is a technology developed as an interim solution to enable voice calls on LTE (Long Term Evolution) networks using existing infrastructure. Here's a deeper dive into VANC's technical details:

Context: The Challenge of Voice on LTE

Early LTE networks were primarily designed for data traffic and lacked native support for voice calls. VANC emerged as a solution before the widespread adoption of VoLTE (Voice over LTE), which provides true voice over IP functionality on LTE networks.

The Role of VANC:

VANC acts as a bridge between the LTE network and the existing 2G/3G (GSM/UMTS) infrastructure responsible for handling voice calls. It essentially translates voice calls initiated on the LTE network into a format compatible with the legacy system, allowing users to make and receive voice calls on their LTE devices.

Technical Breakdown:

  • Access Gateway: VANC functions as an access gateway, providing a point of connection between the LTE Evolved Packet Core (EPC) and the 2G/3G core network.
  • Tunneling: VANC establishes a secure tunnel between the User Equipment (UE) on the LTE network and the Mobile Switching Center (MSC) in the 2G/3G core.
  • Protocol Translation: VANC translates signaling protocols used on LTE (e.g., SIP) to protocols used in the 2G/3G network (e.g., DTAP) for call setup and management.
  • Media Conversion: VANC might also perform media conversion, depending on the specific implementation. Early LTE networks may not have supported voice codecs used in 2G/3G, requiring VANC to convert the audio format for transmission.

VANC Modes:

  • VoLGA A-mode: In this mode, VANC emulates a Base Station Controller (BSC) from the legacy GSM network towards the MSC. This allows the UE to register and communicate using existing GSM protocols.
  • VoLGA Iu-mode: This mode utilizes the Iu-CS interface between the VANC and the MSC, mimicking the behavior of an RNC (Radio Network Controller) from the UMTS network.

Benefits of VANC:

  • Fast Deployment: VANC offered a quicker way to enable voice calls on LTE networks by leveraging existing infrastructure.
  • Reduced Cost: Utilizing existing 2G/3G infrastructure minimized the need for extensive network upgrades.

Limitations of VANC:

  • Complexity: VANC introduces additional network elements and complexity compared to VoLTE.
  • Performance: Voice call quality may be impacted by the additional processing and potential media conversion involved in VANC operation.
  • Limited Scalability: VANC is not designed for long-term scalability and was intended as a temporary solution.

Conclusion:

VANC played a crucial role in enabling voice calls on early LTE networks during a transitional period. While VoLTE has become the preferred solution for voice over LTE, understanding VANC provides insights into the challenges and strategies involved in integrating voice services with newer mobile communication technologies.

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