Section: 6.3.4.2.2 Precoding for large delay CDD
Content: For large-delay CDD, precoding for spatial multiplexing is defined by where the precoding matrixis of size and , . The diagonal size-matrix supporting cyclic delay diversity and the size- matrix are both given by Table 6.3.4.2.2-1 for different numbers of layers . The values of the precoding matrix shall be selected among the precoder elements in the codebook configured in the eNodeB and the UE. The eNodeB can further confine the precoder selection in the UE to a subset of the elements in the codebook using codebook subset restriction. The configured codebook shall be selected from Table 6.3.4.2.3-1 or 6.3.4.2.3-2. For 2 antenna ports, the precoder is selected according to where denotes the precoding matrix corresponding to precoder index 0 in Table 6.3.4.2.3-1. For 4 antenna ports, the UE may assume that the eNodeB cyclically assigns different precoders to different vectors on the physical downlink shared channel as follows. A different precoder is used every vectors, where denotes the number of transmission layers in the case of spatial multiplexing. In particular, the precoder is selected according to , where is the precoder index given by and denote precoder matrices corresponding to precoder indices 12,13,14 and 15, respectively, in Table 6.3.4.2.3-2. Table 6.3.4.2.2-1: Large-delay cyclic delay diversity