Impact of RF transmitter hardware on 5G waveforms: Signal conditioning for UF-OFDM

We compared the 5G candidate waveform UF-OFDM to CP-OFDM, as well as their single carrier DFT-spread variants, with respect to RF transmitter hardware and corresponding signal conditioning algorithms, using both simulations and hardware measurements. Clipping algorithms are used for dealing with the high peak-to-average power (PAPR) issue, while taking care on fulfilling requirements for signal integrity and spectral masks. The fragmented spectrum scenario imposes a special challenge to all waveforms, as band gaps may be filled with clipping noise when using conventional clipping algorithms. We show that by applying the so-called content aware clipping technique to UF-OFDM, we are able to support also narrow band gaps with attenuations in the order of 50 dB. Measurement results for PAPR, error vector magnitude (EVM) and symbol error rate are provided. We show that in general, existing signal conditioning algorithms work smoothly with the UF-OFDM waveform and its DFT-spread variant.