Source: Summary of Rel-17 Work Items (TR 21.917, section 15), ‘Summary of Rel17 WI on NR DSS’ (RP-220464).

Dynamic spectrum sharing (DSS) provides a very useful migration path from LTE to NR by allowing LTE and NR to share the same carrier. DSS was included already in Rel-15 and further enhanced in Rel-16. As the number of NR devices in a network increases it is important that sufficient scheduling capacity for NR UEs on the shared carriers is ensured.

This is addressed by the NR_DSS Work Item (WI), which introduces the support for cross-carrier scheduling from SCell to PCell/PSCell.

When cross-carrier scheduling from an SCell to sPCell is configured:

• PDCCH on that SCell can schedule sPCell’s PDSCH and PUSCH,
• PDCCH on the sPCell can schedule sPCell’s PDSCH and PUSCH but cannot schedule PDSCH and PUSCH on any other cell.

Only one SCell can be configured to be used for cross-carrier scheduling to sPCell.

The maximum number of monitoring candidates and non-overlapping CCEs for PDCCH monitoring (to schedule the sPCell) are split between the sPCell and the SCell used for scheduling the sPCell. The split is indicated via an RRC configured scaling factor.

Note:    sPCell refers to ‘Special Cell’. For Dual Connectivity operation the term Special Cell refers to the PCell of the MCG or the PSCell of the SCG, otherwise the term Special Cell refers to the PCell.

References

List of related CRs: select "TSG Status = Approved" in: https://portal.3gpp.org/ChangeRequests.aspx?q=1&workitem=860043,860143

Acronyms

3GPP Work Plan:

See a listing of all work & study items here:  https://www.3gpp.org/ftp/Information/WORK_PLAN/ and search for ‘DSS’ in the acronym field of the Excel sheet there.

Working Groups:

RAN1

3GPP Release:

Rel-19
Rel-18
Rel-17

See also:

Impacted existing specifications:

IMPORTANT NOTE: Please be aware that these pages are a snapshot of the work going on in 3GPP. The full picture of all work is contained in the Work Plan (https://www.3gpp.org/ftp/Information/WORK_PLAN/)  

Updated: 02/06/2022