Study on unlicensed spectrum offloading system enhancements
3GPP RAN in Rel-13 has worked on integrating "unlicensed access" in RAN, including LTE-WiFi aggregation and LAA. More generically, the work is targeted at several scenarios where the UE is connected to two accesses at once, i.e., a primary access and a secondary access, where the secondary access operates in unlicensed spectrum. The secondary access may be represented by a LAA cell or a WLAN including a set of one or more WLAN APs.
The following two scenarios are considered as per the Rel-14 RAN architecture (TS 36.300 [3]):
- eNB with LTE (primary) + LTE-LAA (secondary) access.
- eNB with LTE (primary) + WLAN (secondary) access.
In both scenarios, the mechanisms defined so far are aiming to make the aggregation of licensed and unlicensed spectrum transparent to the core network elements. In particular, S-GW, PDN GW and PCC elements are not aware of whether the data packets of a PDN or Service Data Flow are being routed (on uplink, downlink or both) on the licensed spectrum cell or the unlicensed spectrum cell.
This TR will study mechanisms to:
- Enable the 3GPP system to differentiate traffic which was transported over unlicensed access in non-roaming and roaming cases.
- Ensure the granularity of data collected for data usage over unlicensed access is as required in order to enable its use for the particular operating purpose (e.g. accounting, charging and network planning). Depending on the operating purpose it can be determined whether the data usage collection is e.g. "per UE" or "average across multiple UEs" etc.
For the aspects above, it is desirable to develop a common framework for LAA and for LWA/LWIP taking into account the Rel-14 RAN architecture, in order to minimize the system impacts and increase flexibility of introducing the LAA and LWA/LWIP solutions in the RAN deployment of an operator.
Interaction with RAN WGs is required to assess solutions that affect the RAN. This work will provide input to SA WG5 for the charging aspects if any identified.