My friend: Hi Ibrahim, I have a question for you.
Me: Go ahead.
My friend: What is the meaning of 5QI in 5G?
Me: 5QI (5G QoS Identifier) is a pointer to a set of QoS characteristics such as priority level, packet delay or packet error rate, etc. (Please check the below snapshot). These QoS characteristics can either be standardized or non-standardized. So, if you look at the table below, you can see different standardized 5QI values for different QoS flow types such as GBR, non-GBR and Delay Critical GBR flows. While 5QI values from 128 to 254 are non-standardized and can be used for operator specific configurations.
My friend: Is it similar to QCI in 4G?
Me: Yes, exactly. But, with the difference that 5QI applies to a flow, carried at some point in a bearer, while QCI applies to a bearer within which certain types of flows are expected. Also, you should note that the 5QI values are as far as possible aligned with the EPS standardized QCI characteristics, defined in 3GPP TS 23.203, which makes mapping of QoS easier for example; during mobility between 5GS and EPS.
My friend: Thanks a lot. Me: You are welcomed.
Source: Ibrahim Sayed
Linkedin Profile: https://www.linkedin.com/in/ibrahim-sayed-88a7747-5g/