5G Core Part 6 — QoS Notification Control
Introduction to QNC
Similar to 4G’s Default and Dedicated bearers, 5G has Default and Dedicated QoS Flows for best-effort and QoS-demanding traffic (e.g., voice, video, autonomous driving etc…) respectively for a Data Network (DN). In 5G, a UE’s Default QoS Flow is always non-Guaranteed Bit Rate (non-GBR), which is suitable for Internet surfing or for the UE to use it to signal GBR and non-GBR Dedicated QoS Flows for the DN. The following shows a UE with the SUPI 304990001003201 having a Default and two (GBR and non-GBR) Dedicated QoS Flows to the DN, voice_video.acme1.com on a 5G Mobile Gateway:
For the above GBR QoS Flow, it has a Maximum Bit Rate (MBR) of 120Kbps and a Guaranteed Bit Rate (GBR) of 100Kbps. This means that the 5G System (5GS) has reserved uplink (UL) and downlink (DL) 100Kbps wireless bandwidth between the UE and the gNB, and wireline bandwidth between the gNB and the UPF for this GBR Dedicated QoS Flow no matter the UE is sending or receiving any traffic or not. The GBR Dedicated QoS Flow ensures the Service Data Flows (SDFs) or network traffic carried by it can meet the expected user experience of the network services. However, this is rather “expensive” from the 5GS network resource usages’ perspective as precious wireless bandwidth is reserved for the lifetime of the GBR Dedicated QoS Flow no matter whether…
