s The complex-valued modulation symbols can be mapped to a maximum of four layers. More specifically, the complex-valued modulation symbols are mapped to x(i) = (i)...x(v-1)(i)] layer,i = 0, 1, where V is the number of layers and Nsymb layer is the number of modulation symbols per layer. If transform precoding is not enabled; for uplink CP-OFDM, y(1)(i) )=x(1)(i) for each layer l = 0, 1, V - 1. However, for DFT-S-OFDM uplink, V = 1, and ((i) depends on the configuration of phase-tracking ref- erence signals. If phase-tracking reference signals are not configured, the block of complex- valued symbols x(0)(0),. 1) for the single-layer v=1 are divided into Niaver INPUSCH sets, each corresponding to one OFDM symbol and = In case phase-tracking reference signals are configured, the block of complex-valued symbols (0) 1) are divided into a number of groups, where each group corre- sponds to one OFDM symbol. The 1th group contains NPUSCH subcarriers and is mapped to the complex-valued symbols (INPUSCH+i') corresponding to the 1th OFDM symbol prior to transform precoding, wherein i'= (0,1,..., NPUSCH The index m of PT-RS samples in the 1th group, the number of samples per PT-RS group Noroup , and the number of PT-RS groups NPT-RS are defined in [6]. The quantity E1 = 1, group when the 1th OFDM symbol contains one or more PT-RS samples, otherwise E1 = 0. New Radio Access Physical Layer Aspects (Part 2) 635 The transform precoding is then performed, resulting in a block of complex-valued symbols of the PUSCH in terms of resource blocks which must satisfy NPUSCH = 2a23a35as where A2, A3, a5 are non-negative integers. The DFT precoding is used to reduce the cubic metric of the uplink signal, thereby enabling higher power-amplifier efficiency. From implementa- tion point of view, it is better to constrain the DFT size to a power of 2. However, such a constraint would limit the scheduler flexibility in terms of the amount of resources that can be assigned for an uplink transmission. In NR, the DFT precoding size, and thus the 