6G codeword-to-layer mapping proposals at RAN1 #126-bis

RAN1 is the radio layer 1 working group, and these sixth-generation (6G) proposals concern agenda item 10.5.2.2. Here, rank denotes the number of transmission layers, while mapping specifies how codewords are assigned across those layers. Ericsson proposed prioritizing downlink schemes "with maximum 2 CWs", where CWs means codewords.

Source: R1-2607754, Ericsson, 3GPP TSG RAN WG1 #126-bis. © Ericsson.

Fraunhofer IIS with Fraunhofer HHI described fixed mapping in fifth-generation New Radio (5G NR). They observed that this mapping "limits the flexibility on number of codewords to schedule". Their observation also cites limits on layer combinations when power or strength differs significantly across layers. Our reading: Fraunhofer's flexibility concern contrasts with Ericsson's priority for schemes capped at two codewords.

Source: R1-2608052, Fraunhofer IIS (with Fraunhofer HHI), 3GPP TSG RAN WG1 #126-bis. © Fraunhofer IIS, Fraunhofer HHI.

NTT DOCOMO with NTT proposed focusing on two alternatives for ranks up to four. Their stated first alternative includes one codeword at rank one. The register marks the ETRI, NTT DOCOMO with NTT, and Fraunhofer IIS with Fraunhofer HHI contributions not treated at RAN1 #126-bis. The cited chair notes passage records an agreement to consider options for downlink shared-channel frequency interleaving. No codeword-to-layer mapping agreement is stated in that passage.