Partitioned Distortion Mitigation in LTE Radio Uplink to Enhance Transmitter Efficiency

This paper proposes a partitioned distortion mitigation technique for both the transmitter and receiver sides of a radio link. The proposed method compensates for the phase nonlinearity at the transmitter side using phase digital predistortion (DPD) and mitigates the amplitude nonlinearity at the receiver side by analyzing the cumulative distribution function of the received signal. The channel effects are also considered and are equalized before the amplitude nonlinearity compensation in the receiver. The performance of the distributed distortion compensation technique is compared, in terms of error vector magnitude (EVM), adjacent channel power ratio, and power efficiency (PE), with current DPD methods. Measurement results show that the proposed partitioned distortion mitigation approach provided an EVM of 1.1% for long-term evolution signals, compared to 2.4% for the conventional power back-off (BO), 2.9% for overdriven digital predistortion (OD-DPD), and 0.48% for complex DPD techniques. The PE significantly improved from 15.8% and 17.9% for the conventional BO and OD-DPD, respectively, to 23% using the proposed method. The bit error rate values at the receiver for the proposed method compare favorably with those of the DPD and phase-only DPD methods.