o-Layer Mapping for Transmit Diversity Number of Number of Layers Code Words Code-Word-to-Layer Mapping i = 0,1, May (i) = d d 0 (2i) x(1) (2i + 1) x(0) (i) = d d 0 (4i) x(2) d(0) (4i + 2 x(3) (i) = d 0 (4i + 3) C 2009 by Taylor & Francis Group, LLC MIMO OFDM Schemes for 3GPP LTE where P E {0,4,5} is the number of the single antenna port used for transmission of the physical channel and i = 0,1,...,Msymb 5.2.3.2 Precoding for Spatial Multiplexing Precoding for spatial multiplexing is only used in combination with layer mapping for spatial multiplexing, as described in Section 5.2.1. Spatial multiplexing supports two or four antenna ports, and the set of antenna ports used is P E {0,1} or P E {0,1,2,3}, respectively. 5.2.3.3 Precoding for Zero- and Small-Delay CDD For zero-delay and small-delay cyclic delay diversity (CDD), precoding for spatial multiplexing is defined by x(v-1)(i) where the precoding matrix W(i) is of size PX v; the quantity D(k) is a diagonal matrix for support of cyclic delay diversity; ki represents the frequency-domain index of the resource element to which the complex-valued symbol y(i) is mapped; and The matrix D(k) should be selected from Table 5.3, where a UE-specific value of 8 is semistatically configured in the UE and the eNodeB by higher-layer signaling. The quantity n in Table 5.3 is the smallest number from the set {128,256,512,1024,2048} such that For spatial multiplexing, the values of W(i) should be selected among the pre- coder 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 restrictions. The configured codebook should be selected from Table 5.5 or Table 5.6. 5.2.3.4 Precoding for Large-Delay CDD For large-delay CDD, precoding for spatial multiplexing is defined by y(0)(i) © 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology Table 5.3 Zero- and Small-Delay Cyclic Delay Diversity Set of Antenna