Digital Pre-Distortion for Radio Transmitters with Multiple Sources of Impairment
Date
2022-08
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Abstract
Among the most important factors in wireless base-stations design are link speed and power efficiency. For a faster wireless connection, the MIMO beamforming technology, higher-order QAM signals, and wider bandwidth signals are used. To increase the power efficiency in transmitters, the PAs are pushed to operate in nonlinear regions where they present their highest power efficiency. These techniques increase in-band and out-of-band distortions of the MIMO wireless transmitters, resulting in signal quality degradation. To mitigate the introduced distortions to the transmitted signal, Digital Pre-Distortion (DPD) is used. However, the conventional DPD techniques cannot meet the strict timing requirements of 5G and 6G wireless connections. The transmitter nonlinearities are a function of various parameters such as input signal average power and ambient temperature and steering angle in the case of beamforming. This thesis studies the effect of ambient temperature and signal’s average power on high-power PAs and proposes a novel DPD technique to mitigate the effect of those parameters on the PA behaviour. In another research, the effect of beamforming on the transmitter performance in terms of signal quality and out-of-band distortions are studied. A novel angle inclusive DPD for beamforming application is introduced to remove beamforming-related distortions and enhance the signal quality. This technique provides an uninterrupted linearization at any beam direction. The developed algorithms are verified using a realistic MIMO beamforming setup designed in the laboratory. The measurement results have shown that by using the proposed technique, the signal quality is substantially improved when compared to state-of-the-art techniques.
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Keywords
Digital Pre-distortion, Power amplifier, Beamforming, 5G
Citation
Motaqi, A. (2022). Digital pre-distortion for radio transmitters with multiple sources of impairment (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.