the precoding operation is defined by: (9-44) Im(x(0)(i)) (y(1)(2i + 1) Im(x(1)(i)) where i = 0, 1, Mayer - 1 with M' = 2M (ayer The precoding for spatial multiplexing using antenna ports with UE-specific reference signals is only used in conjunction with layer mapping for spatial multiplexing. Spatial multiplexing using antenna ports with UE-specific reference signals supports two antenna ports and the set of antenna ports used is p = 7, 8. As an example, for trans- mission over two antenna ports p = 7,8, the precoding operation is defined as: where i = 0, 1, ..,Msymb , For each of the antenna ports used for trans- (9-45) mission of the physical channels, the block of complex-valued symbols y(p) (0), ...,y(p) (Msymb are then mapped in sequence starting with y() (0) to resource element (k,1) such that they are in the resource blocks corresponding to the virtual resource blocks assigned for transmission, and that those resource elements are not used for transmission of PBCH, synchronization signals, cell-specific reference signals, MBSFN reference signals, or UE-specific reference signals, and further those resource elements are not in an OFDM symbol used for PDCCH. The mapping to resource element (k,1) on antenna port p that is not reserved for other purposes is in increasing order of index k and then index 1, starting with the first slot in a subframe. The detailed physical channel processing in the uplink, as shown in Figure 9-70, can be described as follows. The block of bits the number of bits transmitted on 9.15 3GPP LTE physical layer protocols the physical uplink shared channel in one subframe, are scrambled with a UE-specific scrambling sequence prior to modulation, resulting in a block of scrambled bits bo, b1, bMbit-1 according to a pseudo code. The block of scrambled bits bo, b1, bMbii-1 are modulated with QPSK, 16 QAM, 64 QAM, resulting in a block of complex-valued symbols do, d1, dMsymb-1. Note that the 64 QAM modulation scheme is not supported by all UE categories. The block of complex-valued symbol