QFI

Technical Explanation

The QoS Flow Identifier (QFI) is carried in the GTP-U encapsulation header across the N3 interface and in the 1-byte SDAP header over the Uu radio link. It tags every user packet with its specific QoS requirements (delay, jitter, loss rate) as defined by its corresponding 5QI profile.

Key Functions

• Identifies specific QoS Flow within a user PDU Session (values 0 to 63)
• Carried in 1-byte SDAP header over the radio interface
• Directs packet queuing, priority scheduling, and bearer mapping