ze (bits) Figure 4.51 Performance of NR LDPC codes at code rate 1/2, QPSK modulation, and 20 iterations [55]. New Radio Access Physical Layer Aspects (Part 2) 535 4.1.7.5 Modulation Schemes and MCS Determination 3GPP NR supports various modulation schemes (QPSK, 16QAM, 64QAM, and 256QAM) for CP-OFDM in both downlink and uplink. For the DFT-s-OFDM, however, NR uses an additional modulation 2-BPSK in the uplink to achieve better efficiency for power ampli- fiers and lower PAPR in very low data rate cases. While 1024QAM can theoretically pro- vide 25% throughput gain relative to 256QAM, due to real-world implementation complexity and the need for a very high SINR levels to achieve acceptable BLER targets, it was not included in the NR modulation schemes. A constellation diagram is a graphical representation of the complex envelope of each possible symbol state. The power efficiency is related to the minimum distance between the points in the constellation. The bandwidth efficiency is related to the number of points in the constellation. The gray coding is used to assign groups of bits to each constellation point. In gray coding, adjacent constellation points differ by a single bit. The modulation mapping function takes input bit sequence b(i)b(i+1)--b(i+Qm - 1) and generates the corresponding complex-valued modulation symbol y(I+jQ) in the output with the value of V is chosen to achieve equal average power. More specifically, the NR supports the following modulation schemes depending on the channel conditions experienced by the users [6]: 2-BPSK: In this case, bit b(i) is mapped to complex-valued modulation symbol d(i) according to d(i) = 1/2[(1 - 2b(i)) j (j 2b(i))]exp(j(r/2)( mod 2)). BPSK: In this case, bit b(i) is mapped to complex-valued modulation symbol d(i) according to d(i) = 1/2[(1 - 2b(i)) +j(1 2b(i))]. QPSK: In this case, a pair of bits b(2i), b(2i + 1) is mapped to complex-valued modula- tion symbol d(i) according to d(i) = 1/2[(1 2b(2i)) -j(1 - 2b(2i + 1))]. 16QAM: In this case, bit quadruplet b(4i),b(