mapping DM-RS Precoding W Mapping to DM-RS antenna ports Resource mapping Mapping to SRS antenna ports Antenna mapping (Logical to physical antenna mapping) Figure 4.73 Processing of uplink DM-RS with PUSCH. New Radio Access Physical Layer Aspects (Part 2) 593 symbols within a slot are used exclusively for DM-RS transmission, that is, the reference signals are time-multiplexed with the data transmitted on PUSCH from the same device. The NR uses the same DM-RS structure for downlink and uplink in the case of CP-OFDM waveform. For DFT-spread OFDM waveform in the uplink, the DM-RS is based on Zadoff-Chu sequences and supports contiguous allocations and single-layer transmission, similar to LTE, in order to improve the power-amplifier efficiency. Multiple orthogonal ref- erence signals can be generated in each DM-RS occasion where different reference signals are separated in the time, frequency, and code domains. Two different types of DM-RSs can be configured, namely, DM-RS Type 1 and Type 2, which differ in the maximum num- ber of orthogonal reference signals and the mapping to the resource elements in the frequency domain. Type 1 provides up to four orthogonal reference signals using a single- symbol DM-RS and up to eight orthogonal reference signals using a double-symbol DM- RS, whereas Type 2 provides 6 and 12 patterns for single and double-symbol DM-RS, respectively. The DM-RS type 1 or 2 should not be confused with the mapping type A or B (see Section 4.1.2.1), as different mapping types can be combined with different reference signal types. In the following sections, we describe the DM-RSs corresponding to PUSCH and various PUCCH formats for the CP-OFDM uplink waveform. 4.2.2.1.1 PUSCH DM-RS The DM-RS sequence for PUSCH rdd-rs(m) is generated according to = - 2c(2m)) + j(1 - 2c(2m + 1))]/2 where c(i) is a length-31 Gold sequence generated by the pseudo-random sequence generator defined in [6] and initialized with l is the OFDM symbol number within the slot, Nslot is the slot number within a frame, and are giv