This letter proposes a group digital predistorter with step uniformization (SU-GDPD) for massive multi-input multi-output (MIMO) transmitters with hybrid beamforming architecture. Analog predistorters (APDs) are employed to iteratively adjust the nonlinear character of the power amplifiers (PAs) that are sharing one radio frequency (RF) chain. The shared digital predistortion (DPD) parameter and the APD control voltage (ACV) are optimized alternately to achieve the best linearity. This step optimization process avoids extensive search of the ACV combination, which causes much time and calculation resource consumption. Furthermore, SU-GDPD has the adaptability to handle the nonlinearity variation of each PA. Two class-AB PAs with the peak output power of 42 dBm are tested to verify the validation of the proposed SU-GDPD. With the stimulation of the 100-MHz long-term evolution advanced (LTE-A) signal, the two PAs have an average output power of 31 dBm. The adjacent channel power ratio (ACPR) of the two PAs is improved by 19.8-22 dB simultaneously by the proposed SU-GDPD.

中文翻译：

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用于混合波束成形发射机的具有阶跃均匀化的分组数字预失真


这封信提出了一种具有阶跃均匀化的组数字预失真器（SU-GDPD），用于具有混合波束成形架构的大规模多输入多输出（MIMO）发射机。模拟预失真器 (APD) 用于迭代调整共享一个射频 (RF) 链的功率放大器 (PA) 的非线性特性。共享数字预失真（DPD）参数和APD控制电压（ACV）交替优化，以实现最佳线性度。此步骤优化过程避免了对ACV组合的大量搜索，这会导致大量的时间和计算资源消耗。此外，SU-GDPD 具有处理每个 PA 的非线性变化的适应性。对两个峰值输出功率为 42 dBm 的 AB 类 PA 进行了测试，以验证所提出的 SU-GDPD 的有效性。在 100 MHz 长期演进高级 (LTE-A) 信号的刺激下，两个 PA 的平均输出功率为 31 dBm。所提出的 SU-GDPD 同时将两个 PA 的邻道功率比 (ACPR) 提高了 19.8-22 dB。