A Novel Software-Defined Radio Transceiver System with a Dynamic and Adaptive Digital Pre-distortion Solution

This paper introduces a high-value Software Defined Radio (SDR) transceiver system implemented on the zc706 and ad9371-based embedded System-on-Chip. This system has real-time modulated signal generation capabilities and the ability to apply a dynamic and adaptive digital pre-distortion technique(DA-DPD). It continuously calculates the Normalised Mean Square Error (NMSE) and performs further iterations of the Digital Pre-distortion (DPD) only when the NMSE reduces below a particular threshold in the DA-DPD configuration. The memory depth and non-linearity order can be dynamically changed during the execution according to the Power Amplifier (PA) requirements, making the proposed DA-DPD system adaptable to any PA class. For the proof of concept, a 10 MHz LTE signal is transmitted through a 50W GaN Doherty Power Amplifier (DPA) at 3.3 GHz, operating at 8 dB output power backoff (OPBO). The coefficients are extracted in real-time from the received amplified signal. Before performing DPD, the subjected DPA has an Adjacent Channel Leakage Power Ratio (ACPR) of -28.6 dBc (lower) and -29.7 dBc (upper), with NMSE of $\mathbf{- 1 2. 2} \mathbf{d B}$. When the PA is tested with the DA-DPD system, the ACPR and the NMSE have been improved to $\mathbf{- 4 7} \mathbf{d B c}$ and -34 dB, respectively.