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vowifi 3gpp

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Voice over Wi-Fi (VoWiFi) in 3GPP (3rd Generation Partnership Project) refers to the capability of making voice calls over a Wi-Fi network using the IP Multimedia Subsystem (IMS) infrastructure. This technology is part of the broader set of technologies that enable Voice over LTE (VoLTE) and Voice over NR (VoNR) for 4G and 5G networks, respectively.

Here's a technical breakdown of VoWiFi in 3GPP:

  1. IMS (IP Multimedia Subsystem):
    • VoWiFi leverages the IMS, which is a framework for delivering IP multimedia services. It enables the convergence of voice and multimedia services over an IP-based network.
  2. SIP (Session Initiation Protocol):
    • SIP is used for initiating, modifying, and terminating sessions in an IP network. VoWiFi uses SIP for call signaling, allowing devices to set up, modify, and terminate voice sessions.
  3. SDP (Session Description Protocol):
    • SDP is used to describe multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. It is used in VoWiFi to negotiate and describe the characteristics of the voice call.
  4. Roaming and Authentication:
    • VoWiFi involves mechanisms for authentication and authorization, similar to traditional cellular networks. The user's identity and credentials are verified to ensure secure access to the IMS network, even when roaming across different Wi-Fi networks.
  5. IMS Registration:
    • When a device connects to a Wi-Fi network, it registers with the IMS server. This registration process includes authentication and assignment of resources for the voice call.
  6. QoS (Quality of Service):
    • VoWiFi requires a certain level of service quality to ensure a satisfactory voice call experience. Quality of Service mechanisms is employed to prioritize voice traffic over the Wi-Fi network, minimizing latency, jitter, and packet loss.
  7. Media Plane:
    • The media plane carries the actual voice data. Typically, the Real-time Transport Protocol (RTP) is used for transporting the audio, and the Real-time Transport Control Protocol (RTCP) provides feedback on the quality of the transmission.
  8. Handover and Mobility:
    • VoWiFi includes mechanisms for seamless handover between Wi-Fi cells and networks. This is crucial to maintain an ongoing voice call while the user moves within the coverage area of different Wi-Fi access points or switches between Wi-Fi and cellular networks.
  9. Security:
    • Security measures, such as encryption and authentication, are implemented to protect the confidentiality and integrity of voice calls over the Wi-Fi network.
  10. Interworking with Cellular Networks:
    • VoWiFi is designed to seamlessly interwork with cellular networks. For example, a voice call can transition from a cellular network to a Wi-Fi network without dropping, providing a continuous and consistent user experience.

VoWiFi in 3GPP involves a combination of SIP, SDP, IMS, QoS, security, and mobility management to enable voice calls over Wi-Fi networks within the framework of the 3GPP specifications. It provides users with the flexibility to use Wi-Fi for voice communication while maintaining compatibility and continuity with traditional cellular networks.