Gradient-Adaptive Spline-Interpolated LUT Methods for Low-Complexity Digital Predistortion

Campo, Pablo Pascual; Brihuega, Alberto; Anttila, Lauri; Turunen, Matias; Korpi, Dani; Allén, Markus; Valkama, Mikko

doi:10.1109/tcsi.2020.3034825

Cited by 31 publications

(22 citation statements)

References 42 publications

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“…The presented test-bed could thus also be used in such evaluations, focusing on research into PA efficiency enhancement techniques and DPD. Another envisaged application is the research into the linearization of 60 GHz active antennas, similarly to the recent experiment [ 35 ] in the 28 GHz band, with the challenging aspect of multiple PA estimation based on the single observation receiver. Note that although we designed the D/A converter board to allow it to be extended to two channels, the BGT60 modules with integrated VCO [ 42 ] prohibit its direct use in a two-channel multiple input–multiple output (MIMO) scenario.…”

Section: Digital Predistortion Experiments On Modulated Waveformsmentioning

confidence: 99%

“…The state-of-the-art experimental research is mainly based on expensive universal measurement devices such as high-speed arbitrary waveform generators (AWG) and real-time spectrum analyzers or fast oscilloscopes [ 32 , 33 , 34 ]. A multi-Gb/s general-purpose AWG and oscilloscope have also been used in a recent demonstration of DPD in the 28 GHz band [ 35 ]. The use of such general-purpose equipment significantly increases the costs of the overall system and prohibits the wider deployment of predistortion in commercial mm-wave applications.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we present our wideband (up to 900 MHz bandwidth without predistortion) experimental 60 GHz transmitter test-bed with an observation receiver (denoted below simply as the receiver), which was developed not using expensive laboratory instruments [ 32 , 33 , 34 , 35 ] but with affordable development kits and discrete components selected to target low-phase noise and sampling clock jitter. The described test-bed is fully MATLAB-controlled and, in contrast to similar recent setups, it contains digital compensation for the RF front-end including amplitude and phase mismatch and power amplifier linearization using digital predistortion.…”

Section: Introductionmentioning

confidence: 99%

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Digitally-Compensated Wideband 60 GHz Test-Bed for Power Amplifier Predistortion Experiments

Pospíšil

Mars̆álek

Götthans

et al. 2021

Sensors

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Millimeter waves will play an important role in communication systems in the near future. On the one hand, the bandwidths available at millimeter-wave frequencies allow for elevated data rates, but on the other hand, the wide bandwidth accentuates the effects of wireless front-end impairments on transmitted waveforms and makes their compensation more difficult. Research into front-end impairment compensation in millimeter-wave frequency bands is currently being carried out, mainly using expensive laboratory setups consisting of universal signal generators, spectral analyzers and high-speed oscilloscopes. This paper presents a detailed description of an in-house built MATLAB-controlled 60 GHz measurement test-bed developed using relatively inexpensive hardware components that are available on the market and equipped with digital compensation for the most critical front-end impairments, including the digital predistortion of the power amplifier. It also demonstrates the potential of digital predistortion linearization on two distinct 60 GHz power amplifiers: one integrated in a direct-conversion transceiver and an external one with 24 dBm output power.

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Section: Digital Predistortion Experiments On Modulated Waveformsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Digitally-Compensated Wideband 60 GHz Test-Bed for Power Amplifier Predistortion Experiments

Pospíšil

Mars̆álek

Götthans

et al. 2021

Sensors

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“…Of course, many digital predistortion techniques for PAs exist. While these algorithms reduce OoB emissions near the fundamental transmit frequency, the influence on harmonics is not covered [25]- [27]. From a self-interference cancellation perspective, many computationally expensive general learning concepts could be adapted to the Tx harmonics issue.…”

Section: Introductionmentioning

confidence: 99%

Low-Complex Digital Cancellation of Transmitter Harmonics in LTE-A/5G Transceivers

Paireder

Huemer

2021

IEEE Open J. Commun. Soc.

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Nowadays, mobile communication radio frequency transceivers for LTE-A/5G usually operate in frequency-division duplex mode and support carrier aggregation. The resulting complexity requires compromises in the analog front-end. One consequence is a limited stop-band attenuation of the duplex filters that separate the transmit and the receive paths. The resulting transmit leakage signal combined with other non-idealities, like power amplifier (PA) harmonics, can create self-interference problems that desensitize the receivers. In this work, we propose an optimized digital self-interference cancellation scheme to mitigate the unacceptable performance degradation caused by PA induced harmonics. We derive an appropriate interference model and quantify the interference power levels for a specific PA. Based on these results, our low-complex cancellation approach solely targets the dominating components. Our algorithm relies on the auto-covariance matrix for the second and third power of LTE signals, which we derive for the first time in an analytic form. This statistical information can be combined with the transform-domain concept to noticeably improve the performance of a least-mean squares based cancellation algorithm. The capabilities of the approach are demonstrated by means of simulations and are validated on measurement data.

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“…While the PH model has been shown to be an accurate model for DSIC, it suffers from high complexity, making real-time implementation very challenging, especially with wider bandwidths. In [11], [27], which serve as a starting point or background for this paper, we proposed a Hammerstein model for DSIC and DPD, respectively, building on spline-interpolated LUTs and simple adaptive learning rules.…”

mentioning

confidence: 99%

Cascaded Spline-Based Models for Complex Nonlinear Systems: Methods and Applications

Campo

Anttila

Korpi

et al. 2021

IEEE Trans. Signal Process.

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In this paper, we present a class of cascaded nonlinear models for complex-valued system identification, aimed at baseband modeling of nonlinear radio systems. The proposed models consist of serially connected elementary linear and nonlinear blocks, with the nonlinear blocks implemented as uniform spline-interpolated look-up tables (LUT) and the linear blocks as FIR filters. Wiener, Hammerstein, and Wiener-Hammerstein models are built, and simple but efficient gradient based adaptive learning rules are derived for all the models. This approach leads to remarkably simple solutions in terms of computational complexity, making the techniques suitable for realtime implementation. The proposed methods are then applied to full-duplex self-interference cancellation and digital predistortion in various real-life scenarios. First, evaluations with measured data from an in-band full-duplex prototype working at 2.4 GHz ISM band show that the algorithms are capable of obtaining similar cancellation performance as existing state-of-theart solutions, regardless of the clearly reduced complexity. Second, a mmW active antenna array working at 28 GHz center frequency is digitally predistorted with the proposed solutions. The unwanted emissions and nonlinear distortion are suppressed to similar levels as with other state-of-the art solutions, and the corresponding linearity specifications are fulfilled in all cases, while the processing complexity is again drastically reduced.

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Gradient-Adaptive Spline-Interpolated LUT Methods for Low-Complexity Digital Predistortion

Cited by 31 publications

References 42 publications

Digitally-Compensated Wideband 60 GHz Test-Bed for Power Amplifier Predistortion Experiments

Digitally-Compensated Wideband 60 GHz Test-Bed for Power Amplifier Predistortion Experiments

Low-Complex Digital Cancellation of Transmitter Harmonics in LTE-A/5G Transceivers

Cascaded Spline-Based Models for Complex Nonlinear Systems: Methods and Applications

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