Low PAPR reference signal transceiver design for 3GPP 5G NR uplink

Low peak-to-average-power ratio (PAPR) transmissions significantly improve the cell coverage as they enable high power transmissions without saturating the power amplifier. To support the low PAPR transmissions,pi/2-BPSK-based data and DMRS are introduced in the latest version of 5G NR specifications. In addition to that, the spatial multiplexing support is also extended to pi/2-BPSK data transmissions. The DMRS sequences corresponding to these spatial streams (users) are frequency division multiplexed (FDM). However, the spectrum shaping process employed in the generation of pi/2-BPSK waveforms is frequency selective and hence results in asymmetric spectrum shaping effect on DMRS sequences, when they are frequency multiplexed. This subsequently results in a non-uniform block error (BLER) and PAPR performances across the spatial users, which in turn may result in inter user interference across the spatial users. In this paper, we propose two transmitter architectures, namely method 1 and method 2, to generate low PAPR pi/2-BPSK-based DMRS waveforms. The proposed architectures ensure that the spectrum shaping effect is uniform across all the spatial streams. We corroborate through simulations that the proposed architectures will result in identical block error and PAPR performances across all the spatial streams.