Background
–In Rel-15/16, the codebook is designed for coherent transmission within one TRP operation, e.g.,
•Type I Single-Panel Codebook
•Type I Multi-Panel Codebook
•Type II Codebook/Enhanced Type II Codebook
•Type II Port Selection Codebook/Enhanced Type II Port Selection Codebook
Issue
–However, for SDM PDSCH transmission schemes with multiple TRPs, NC-JT CSI with multiple TRPs is not supported
–Besides, how dose the gNB determine whether PDSCH is transmitted with SDM PDSCH Tx schemes or S-TRP based Tx schemes
Need
–The CSI feedback design for NC-JT with multiple TRPs needs to be considered.
38.214-h50 5.2.1.4.1 Resource Setting Configuration
•An NZP CSI-RS Resource Set for channel measurement with 2≤K_s≤8 resources can be configured with two Resource Groups, with K_1≥1 resources in Group 1 and K_2≥1 resources in Group 2, such that K_1+K_2=K_s, and with N∈{1,2} Resource Pairs. Each Resource Pair consists of one resource from Group 1 and one resource from Group 2.
38.331-h40 IE NZP-CSI-RS-ResourceSet
Multi-TRP NCJT Measurement Hypothesis
•Single CSI reporting setting
–Mode 1 (One NCJT CSI + S-TRP CSI):
•the UE can be configured to report X∈{0,1,2} CSIs associated with single-TRP measurement hypotheses and one CSI associated with NCJT measurement hypothesis
–X: the number of reported CSIs for S-TRP
–Mode 2 (Best CSI among NCTJ & S-TRP):
•the UE can be configured to report one CSI associated with the best one among NCJT and single-TRP
•38.331-h40 IE CSI-ReportConfig