What is Reflective QoS in 5G?

My friend: Hi Ibrahim, I have a question for you.

Me: Please, go ahead.

My friend: While checking our last discussion about QoS in 5G (see below link), I found one term we didn’t discuss named Reflective QoS, what is it exactly? https://www.5gworldpro.com/5g-knowledge/215-is-qos-in-5g-same-as-4g.html

Me: Actually, this is one of the most intelligent new concepts introduced in 5G which I really like and it is a simple method to perform QoS in UL with less signaling between the UE and the core.

My friend: Great, but how does it work?

Me: First, the UE will indicate that it supports Reflective QoS during PDU session establishment or modification, then when the UPF receives from SMF an indication to use Reflective QoS for a certain QoS flow, so UPF will include in the encapsulation header of the packets sent to gNB via N3 interface a new field named RQI (Reflective QoS Indicator). When the gNB receives the RQI and QFI from UPF, it’ll indicate it to the UE, so the UE will just monitor the header and once RQI is set, so it’ll apply same QoS in DL to all UL data packets transmission with no specific signaling to tell the UE which QoS will be used in UL.

My friend: Thanks a lot.

Me: You are welcome.

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Source: Ibrahim Sayed

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