3GPP 23.501 v20.2.0 — the document's own text

5.31.14.1 General

Taught in 25. Small devices, small messages (The 5G system architecture, in depth).

The rate of user data sent to and from a UE (e.g. a UE using CIoT 5GS Optimisations) can be controlled in two different ways:

Serving PLMN Rate Control;
Small Data Rate Control.

Serving PLMN Rate Control is intended to allow the Serving PLMN to protect its AMF and the Signalling Radio Bearers in the NG-RAN from the load generated by NAS Data PDUs.

Small Data Rate Control is intended to allow HPLMN operators to offer customer services such as "maximum of Y messages per day".

NOTE: Existing Session-AMBR mechanisms are not suitable for such a service since, for radio efficiency and UE battery life reasons, an AMBR of e.g. > 100kbit/s is desirable and such an AMBR translates to a potentially large daily data volume.

The SMF in the Serving PLMN may send the Small Data rate control parameter for an emergency PDU session.