Voice over NR Call Flow

Voice over New Radio (VoNR) is a term used to describe voice services delivered over the 5G New Radio (NR) network. VoNR offers improvements in voice quality, latency, and efficiency compared to previous generations of voice services. Below is a detailed technical explanation of the VoNR call flow:

1. Network Registration:

a. UE (User Equipment) Registration:
The process begins when the User Equipment (UE), which is the 5G-enabled device, initiates a registration request to the 5G Core (5GC) network. This request is sent through the Radio Access Network (RAN).

b. Network Authentication and Authorization:
The 5GC validates the UE’s credentials and authenticates it. Once authenticated, the 5GC authorizes the UE for VoNR services based on subscription data and network policies.

2. Session Setup:

a. PDU Session Establishment:
A Packet Data Unit (PDU) session is established between the UE and the 5G Core. This session provides the necessary data path for the VoNR call.

b. RAN Connection Setup:
The RAN establishes a connection with the UE using the 5G NR air interface. This connection provides the radio access needed for VoNR communication.

3. VoNR Call Establishment:

a. SIP Signaling:
The UE initiates a Session Initiation Protocol (SIP) signaling request to set up the VoNR call. The SIP message contains information like caller ID, callee ID, and media capabilities.

b. Media Negotiation:
The SIP signaling facilitates the negotiation of media parameters between the calling and called parties. This includes determining the codec to be used, media types (audio, video), and other call attributes.

c. Media Path Establishment:
Once media parameters are agreed upon, the media path for the VoNR call is established. This involves setting up the necessary bearer paths and Quality of Service (QoS) parameters to ensure optimal voice quality and low latency.

4. Call Handling:

a. Voice Transmission:
During the call, voice data is encoded, transmitted over the 5G NR network, and decoded at the receiving end. The chosen codec ensures efficient compression and decompression of voice data to maintain high-quality voice communication.

b. QoS Management:
The 5G network continuously monitors and manages the QoS parameters like latency, jitter, and packet loss to ensure a seamless VoNR experience. If network conditions deteriorate, the network may apply adaptive techniques like codec switching or bandwidth adjustment to maintain call quality.

5. Call Termination:

a. SIP Termination:
Upon call completion, the SIP signaling messages facilitate the termination of the VoNR call. This involves sending SIP messages to release the media resources and signaling connections established during the call.

b. PDU Session Release:
Once the call is terminated, the PDU session between the UE and the 5G Core is released, freeing up network resources allocated for the VoNR call.

Conclusion:

VoNR call flow leverages the capabilities of the 5G New Radio (NR) network to deliver high-quality voice services with enhanced efficiency, low latency, and improved user experience. The call flow involves multiple steps, including network registration, session setup, call establishment, call handling, and call termination, each optimized to ensure seamless VoNR communication.