Section: 6.3.3.2 Layer mapping for spatial multiplexing
Content: For spatial multiplexing, the layer mapping shall be done according to Table 6.3.3.2-1. The number of layers is less than or equal to the number of antenna ports used for transmission of the physical channel. The case of a single codeword mapped to multiple layers is only applicable when the number of cell-specific reference signals is four or when the number of UE-specific reference signals is two or larger. For subslot/slot-PDSCH, the number of codewords is always one. Table 6.3.3.2-1: Codeword-to-layer mapping for spatial multiplexing