Many people ask: “5G NSA or even 5G SA already gives great speed, latency and quality – so why do operators now push 5G-Advanced (3GPP Rel-18) to consumers, not just enterprises?”
Yes, the commercial/marketing side is essential. But there is also a powerful technical story behind 5G-Advanced – and honestly, the differences vs. “plain” 5G SA are clear.
From “network-centric” to application-aware
One of the most critical changes in Rel-18 is application awareness, especially for future XR services (VR, AR, MR). With XR, we’re not just streaming a simple video. We mix ultra-low-latency control traffic, critical audio and high-bitrate visual data all in real time. This can transform education, healthcare, entertainment, training, remote assistance and many other parts of daily life.
Today, many XR use cases are still in demo or early-stage deployments, but real applications are already emerging across industries. 5G-Advanced is being designed to support these at scale, not just in a lab.
What does Rel-18 actually change for XR QoS?
In Rel-17 and earlier, QoS differentiation stopped at the QoS flow level – all PDUs in a flow were treated the same. Rel-18 introduces per-PDU set QoS inside a single QoS flow.
The network can now understand the purpose of PDUs within a media stream and change radio scheduling in NG-RAN accordingly.
Downlink direction:
The Application Function (AF) provides PDU set QoS parameters to the network:
-
- PSDB (PDU Set Delay Budget) – max delay for a PDU set
- If the PSDB is likely to be exceeded, the network might discard the PDU set to save resources for more timely data.
- PSER (PDU Set Error Rate) – max error rate for the PDU set
- This parameter guides link-layer protocol configurations (e.g., RLC and HARQ retransmissions) to meet the application’s error tolerance for the entire set.
- PSIHI (PDU Set Integrated Handling Indication) – whether all PDUs in the PDU set are needed by the app
- If the PSIHI is set to “true” or indicates that the entire set is necessary (often implying low importance if incomplete), and some PDUs are lost or delayed, the network node (e.g., the gNB) can discard the remaining PDUs of that set, thus saving radio resources.
- PSDB (PDU Set Delay Budget) – max delay for a PDU set
A PDU set typically corresponds to a video frame. A new 3GPP RTP header extension (TS 26.522) lets the application mark which PDUs belong to which PDU set and the importance of each PDU set (PSI). The UPF then uses this to mark PDUs in GTP-U towards the NG-RAN. So, under congestion, NG-RAN can protect high-importance PDUs (e.g. audio, key frames, control) and discard low-importance PDUs or even whole PDU sets that are already “broken”, freeing radio resources instead of wasting them, which leads to a smoother XR experience, fewer visible artefacts, and better stability when the network is under stress.
Uplink direction:
The UE gets a UL protocol description and a DRB discard configuration. If one PDU in a PDU set is discarded (timer expired), the UE discards the rest of that PDU set too. This keeps uplink behaviour consistent with the PDU-set concept and helps the network use resources more efficiently.
So, why 5G-Advanced for consumers?
Because future consumer services are not just about peak Mbps anymore. They’re about: consistency under load, intelligent QoS inside the flow, and application-aware behaviour for XR, cloud gaming, real-time interactive apps, etc.
5G-Advanced (Rel-18) is the step from “fast 5G” to “smart 5G,” where the network understands what the application needs within the stream and acts accordingly.
So, aside from the commercial side, this is why operators are moving now, even though today’s users already feel “happy enough” with 5G.