ignals using a double-symbol DM-RS, whereas Type 2 can provide 6 and 12 patterns depending on the number of symbols. The DM-RS Type 1 or 2 should not be confused with the mapping Type A or B, since different mapping types can be combined with different reference signal types. Reference signals should preferably have small power variations in the frequency domain to allow a similar channel-estimation quality for all frequencies spanned by the reference signal. Note that this is equivalent to a highly localized time-domain autocorrelation of the transmitted reference signal. New Radio Access Physical Layer Aspects (Part 2) 421 The PDSCH DM-RS sequence r'DM-RS(n) is defined as [`DM-RS(n) = { = {[1 2c(2n) + j[1 - 2c(2n+1)]}/V2, where c(i) is a length-31 Gold sequence generated by the pseudo-random sequence generator defined in [6] and initialized with Cinit latter expression, l denotes the OFDM symbol number within the slot, Nslot is the slot number within a frame, and NSCID = {0,1} is given by the DM-RS sequence initialization field in the DCI associated with the PDSCH transmission, if DCI format 1_1 is used and Nnscid = {0, 1, 65535} is the scrambling identifier when signaled by higher layer parameters scramblingIDC and scramblingIDI; otherwise NSCID = 0 and = Ncell The PDSCH is scheduled by PDCCH using DCI format 1_1 (or DCI format 1_0) with CRC scrambled by C-RNTI, MCS-C- RNTI, or CS-RNTI [6]. The PDSCH DM-RS can be mapped to physical resources in two ways referred to as con- figuration Type 1 or 2, which is determined by RRC parameter dmrs-Type. Prior to resource mapping, the sequence r'DM-RS(m) is multiplied by scaling factor BDMRS H to adjust the trans- mission power and is mapped to resource element (RE) (k,1) as a(k,1) = BPDSCHWf(k)wt(l)rDM-Rs(2n+k) DDMRS where wf(k') and wt(l') are orthogonal cover codes or spreading functions across frequency and time that are given in [6]. In the latter expression, and 1k'=0,1 and k = 4n + 2k + A for configuration Type 1 and + A for configuration Type 2. In DM-RS Type 1, 