Spline-Based Adaptive Cancellation of Even-Order Intermodulation Distortions in LTE-A/5G RF Transceivers

Abstract

Radio frequency transceivers operating in in-band full-duplex or frequency-division duplex mode experience strong transmitter leakage. Combined with receiver nonlinearities, this causes intermodulation products in the baseband, possibly with higher power than the desired receive signal. In order to restore the receiver signal-to-noise ratio in such scenarios, we propose two novel digital self-interference cancellation approaches based on spline interpolation. Both employ a Wiener structure, thereby matching the baseband model of the intermodulation effect. Unlike most state-of-the-art spline-based adaptive learning schemes, the proposed concept allows for complex-valued inand output signals. The optimization of the model parameters is based on the stochastic gradient descent concept, where the convergence is supported by an appropriate step-size normalization. Additionally, we provide a gain control scheme and enable pipelining in order to facilitate a hardware implementation. An optional input transform improves the performance consistency for correlated sequences. In a realistic interference scenario, the proposed algorithms clearly outperform a state-of-the-art least mean squares variant with comparable complexity, which is specifically tailored to second-order intermodulation distortions. The high flexibility of the spline interpolation allows the splinebased Wiener models to match the performance of the kernel recursive least squares algorithm at less than 0.6 % of the arithmetic operations.

Air-Induced Passive Intermodulation in FDD MIMO Systems: Algorithms and Measurements

“…In addition to PIM modeling and cancellation, the works in [3], [4], [25], [26], [27], [28], [29], and [30] have considered the cancellation of the intermodulation distortion imposed by active components, primarily the TX PA systems. However, these works do not consider PIM, yet it is noted that similar behavioral modeling principles apply when the source of the intermodulation distortion is an active component.…”

Predistortion-Based Linearization for 5G and Beyond Millimeter-Wave Transceiver Systems: A Comprehensive Survey

“…− The majority of the representative works in sequential W/H and memoryless equalization models have captured linear MEs, yielding stable learning convergence while inherently obviating the suitability for real-time systems with limited computational resources. However, the recent advancements in such models, the move towards developing the Wiener structure for online cancellation of TRX self-interference, and the flexible combination of ANN with W/H models paved the way for the recursive coefficient adaption in full-duplex strategy to be an enabling linearization method for both contemporary 5G and future communications [107], [108]. − As highlighted in previous subsections, to enable the • Difficulties regarding the curse of input signal dimensionality in large bandwidths remain a challenge stability of computing algorithm relaying, some advanced pruning algorithms should be adopted to reduce the basis function orthogonalization to a tolerable level.…”

In-band full-duplex dual-band transceiver based on single-core multiport architecture

“…To this purpose, typical multiband transceivers consist of independent transmitting and receiving front-end pairs. They are usually based on heterodyne or homodyne architectures [23][24][25][26][27][28][29][30][31] , with each front-end pair operating independently via separate local oscillators (LO) at specified frequencies. Unfortunately, these front ends do not share their circuitries.…”