Telecommunication

What is VoLGA Voice over Long Term Evolution via Generic Access Network

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VoLGA (Voice over LTE via Generic Access Network): A Bridge Between Legacy and LTE Networks

VoLGA (Voice over LTE via Generic Access Network) emerged as a transitional technology to enable voice services over new LTE (Long Term Evolution) networks while leveraging existing infrastructure for voice calls. Here's a detailed technical explanation:

Context:

  • LTE Networks: LTE networks are designed for high-speed data traffic but initially lacked native support for legacy voice services like those used in 2G and 3G networks.
  • Need for Voice Continuity: As mobile operators transitioned to LTE, they needed a solution to ensure voice services remained functional for existing subscribers.

VoLGA as a Bridge:

VoLGA acts as a bridge between the new LTE data network and the existing infrastructure used for voice services (typically 2G/3G core networks). This allows voice calls to be carried over the existing infrastructure while data traffic benefits from the high speed and capacity of the LTE network.

Technical Components:

  • Generic Access Network (GAN): VoLGA builds upon the concept of GAN (Generic Access Network), a standard that allows extending mobile services over generic IP access networks. In VoLGA's case, the existing 2G/3G network acts as the generic IP access network.
  • VoLGA Modes: VoLGA supports two primary modes for voice service delivery:
    • VoLGA A-mode: This mode extends GSM (Global System for Mobile Communications) Circuit Switched (CS) services over the LTE network. It tunnels Non-Access Stratum (NAS) protocols, responsible for call control signaling, between the User Equipment (UE) and the Mobile Switching Center (MSC) in the 2G core network.
    • VoLGA Iu-mode: This mode extends UMTS (Universal Mobile Telecommunications System) CS services over the LTE network. It tunnels NAS protocols between the UE and the Serving GPRS Support Node (SGSN) in the 3G core network.
  • Tunneling Protocols: VoLGA utilizes tunneling protocols like GTP (GPRS Tunneling Protocol) to encapsulate NAS packets and transport them over the EPS bearers (Evolved Packet System bearers) within the LTE network.

Benefits of VoLGA:

  • Smooth Transition to LTE: VoLGA facilitated a smoother transition to LTE networks by ensuring voice service continuity for existing subscribers.
  • Reduced Costs: Operators could leverage existing 2G/3G core network infrastructure for voice while deploying new LTE infrastructure for data services, potentially reducing upfront costs.
  • No Legacy Network Fallback: Unlike some solutions, VoLGA doesn't require fallback to legacy networks for voice calls, maintaining a consistent user experience on the LTE network.

Limitations of VoLGA:

  • Transitional Technology: VoLGA was intended as a temporary solution. As VoLTE (Voice over LTE) matured, offering native voice over IP capabilities within the LTE network, the need for VoLGA diminished.
  • Limited Scalability: VoLGA relies on existing 2G/3G core networks, which may not scale effectively for increasing voice traffic demands.
  • Security Considerations: VoLGA inherits some security limitations from the underlying 2G/3G core networks.

Conclusion:

VoLGA played a crucial role in enabling a smooth transition from legacy voice networks to the new era of LTE data networks. While largely superseded by VoLTE, VoLGA serves as a testament to the ingenuity employed to bridge technological advancements and maintain service continuity during network upgrades.

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