5G-NR-Modulation-Demodulation

The implementation of 5G NR Modulation and Demodulation

Modulation

symbOut = nrModuMapper(bitsIn,moduType) maps the bit sequence into complex modulation symbols using modulation scheme specified in TS 38.211 Section 5.1 The modulation scheme, moduType must be one of 'BPSK', 'QPSK', '16QAM', '64QAM', '256QAM'.

Demodulation

softBits = nrSoftModuDemapper(symbsIn,moduType,N0,method) demodulates the complex symbols symbsIn using soft decision. The modulation scheme, moduType must be one of 'BPSK', 'QPSK', '16QAM', '64QAM', '256QAM'. symbsIn must be a column vector. 'mothod' - Specified as 'max-log-map' or 'approx'.

Demodulation is performed according to the constellations given in TS 38.211 section 5.1 including the power normalization factors specified. The factors: 1/sqrt(2) for BPSK, and QPSK, 1/sqrt(10) for 16QAM, 1/sqrt(42) for 64QAM and 1/sqrt(170) for 256QAM.

Source Paper: Mao, Juquan, et al. "A low complexity 256QAM soft demapper for 5G mobile system." 2016 European Conference on Networks and Communications (EuCNC). IEEE, 2016.

Author Dr J Mao

Email: [email protected]

2021 Nov

 Example:
 %Demonstrate 16-QAM  demodulation.
 msg = randi([0 1],100,1,'int8');
 symb = nrModuMapper(msg,'16QAM');
 N0 = 0.1;
 rxsymb = symb + sqrt(N0/2)*randn(size(symb)) ;
 msg_hat = nrSoftModuDemapper(msg_hat,'16QAM',N0,'max-log-map');
 numErr = sum(msg ~=(msg_hat < 0));