Disclaimer : This may not seem a complete standalone article, specifically written for my own reference from the webinar
Excerpts from Keysight presentation (DSS Overview and Testing)
- When NR is transmitted in “DSS mode” — NR signals and channels are transmitted in overlapping over the LTE carrier.
- Key to ensure that none of the channels/signals of “NR-DSS” should overlap
i) Resource Elements that contain LTE-CRS symbols
ii) Symbols that contain LTE-Control Symbols
This necessitates “puncturing” the NR-data symbols (not the DMRS symbols) in the NR PDSCH while transmitting. This is called “LTE-CRS Rate-Matching of NR DSS”. A key feature enabled in Rel 15 and UE needs to know this while FEC decoding of the Data in NR-PDSCH when transmitted in DSS mode. The Rate-Matching pattern information is communicated to the UE. This “Rate-Matching pattern information” includes essential information of the LTE system (for e.g #number of CRS Ports of LTE system)
How to Transmit SS/PBCH in DSS Mode
No LTE-CRS symbols should be overlapped and No SSB blocks should be punctured for ratematching with LTE-CRS. A continous 4symbols needed so that alteast one SSB block can be transmitted !!
2-Port CRS
- Specifically for DSS NR transmission only 30kHz SCS of Case C is feasible, since no “LTE-CRS Rate-Matching for SSB signals allowed
- NR Case B : LTE Symbol 4 (LTE-CRS) overlaps with NR SSB at symbol 8 and 9 !! (So Case B & C not aall the SSB blocks suitable for NR tranmssion in DSS )
4-Port CRS
- Only 1 SSB block, poor synchronization => low mobility only and limited to single beam
See presentation here
