Hardware Impairments in Millimeter Wave Communications using OFDM and SC-FDE

Millimeter wave (mmWave) communications are recognized as a key technology in 5G architecture by achieving highly boosted data rates due to the large available bandwidth. For proper mmWave air interface design, the impact of hardware impairments leading to performance degradations have to be considered adequately in practical systems. In this paper, we study the hardware aspects phase noise, non-linear power amplifiers, IQ imbalance, and analog-to-digital converter (ADC) resolution using appropriate models at mmWave frequency and evaluate the performance in an outdoor urban mmWave scenario. The respective influence on two air interfaces, namely, orthogonal frequency division multiplexing (OFDM) and single-carrier frequency domain equalization (SC-FDE), are analyzed and compared. It is shown that SC-FDE is much more robust against impairments from non-linear power amplifiers, IQ imbalance and ADC resolution than OFDM for a typical mmWave system configuration. Although this less robustness of OFDM systems is compensated by channel coding significantly, SC-FDE with minimum mean square error equalization can still outperform OFDM in some coded cases.