On the Design of Optimal Soft Demapper for 5G NR Wireless Communication Systems

The fifth telecommunication generation new radio (5G NR) modulations enable transmissions to have high data rates although in the environments having large channel distortions and noise. However, the third generation partnership project (3GPP) only standardized the mapper of 5G NR, but left the design of demapper for the industries. This paper proposes an optimal soft demapper for all 5G NR modulations for better performances and practical implementations. The proposed soft demapper is optimized in terms of minimum bit-error rate (BER) subject to the limited practical soft values required by the hardware. We conduct a series of computer simulations to evaluate the performances of the proposed soft demapper without and with soft decoder. The simulation results confirmed that the proposed 5G NR demappers provide excellent performances without error-floor as expected by the theoretical BER curve performances for the case of without channel coding and more than 5 dB gain without error-floor for the case of decoding using soft decoders of convolutional and repetition codes. These results are expected to provide contribution to the development of practical 5G NR receivers.