On the Effects of PA Nonlinearities for Hybrid Beamforming Based Wideband Massive MIMO Systems

© 2020 IEEE.In this paper, we present a general framework for the investigation of the effects of power amplifier (PA) non-linearities on the hybrid beamforming based massive multiple-input multiple-output (MIMO) systems. In literature, much of the attention is devoted to phase shifters as the analog beamformer stage; however, in this work, a more comprehensive scenario, based on fully connected analog beamformer architecture, is considered. Firstly, out-of-band (OOB) radiation pattern is evaluated to investigate the spatial characteristics of the undesired radiation. It is observed that OOB radiation due to nonlinear distortion is concentrated on the beamforming directions. In addition, a framework is proposed to design digital predistorters (DPD) and a conventional DPD architecture is adopted to the proposed design framework. It is shown that conventional DPD can solve the OOB problem for a single user environment; however, its performance degrades in the multi-user case. Even though, there are many studies on the effects of nonlinear PA distortions, a few of them consider the achievable information rate (AIR). In this work, a framework is adopted to study the capacity of the considered system under PA nonlinearities.


An experimental study on Power Amplifier linearisation by artificial neural networks Yapay Sinir Aǧlari ile Güç Yükselteç Doǧrusalląstirma Amaçli Deneysel Bir Çalisma
Yesil, Soner; Kolagasioglu, Ahmet Ertugrul; Yılmaz, Ali Özgür (2018-07-05)
This paper represents an experimental study on the linearisation of Power Amplifiers especially on high output power regions by utilizing an artificial neural network structure and open-loop training method. For the same in-band output power, 9dB EVM and 6dB ACLR improvement has been observed on hardware by feeding the proposed digital predistortion signal (DPD) to the PA under test.
On some cryptographic properties of Rijndael
Kavut, S; Yucel, MD (2001-01-01)
We examine diffusion properties of Rijndael which has been selected by US National Institute of Standards and Technology (NIST) for the proposed Advanced Encryption Standard (AES). Since the s-box of Rijndael applies a nonlinear transformation operating on each byte of the intermediate cipher result independently, its characteristics have significant effects on the strength of the entire system. The characteristics of Rijndael's s-box are investigated for the criteria of avalanche, strict avalanche, bit ind...
Investigation of Alternative Array Configurations of Nanowires for Maximum Power Transmission at Optical Frequencies
Karaosmanoglu, Bariscan; Satana, Hasan Aykut; Dikmen, Fatih; Ergül, Özgür Salih (2017-07-14)
We present a computational analysis and comparison of nanowire arrays for efficient transmission of electromagnetic power at optical frequencies. A reliable simulation environment involving the multilevel fast multipole algorithm for fast iterative solutions of surface integral equations is used to accurately compute field intensity and power density values in the vicinity of nanowires in diverse configurations. The results demonstrate favorable properties of honeycomb structures that can provide efficient ...
Investigation of Effects of PA Non-linearities on the Fully Digital Massive MIMO Systems
Salman, Murat Babek; Güvensen, Gökhan Muzaffer; Çiloğlu, Tolga (2020-01-01)
In this study, effects of power amplifier (PA) non-linearities on the performance of fully digital massive MIMO systems are studied. Fully digital systems have been studied extensively in the literature. However, research on the effects of PA non-linearities is limited to assessment of out-of-band (OOB) radiation pattern of the received signal. In this paper, we introduce another metric to evaluate the performance of the digital MIMO systems, which are subject to PA non-linearities, in terms of achievable i...
Investigation of modular multilevel converter control methods
Ertürk, Feyzullah; Hava, Ahmet Masum; Department of Electrical and Electronics Engineering (2015)
The thesis focuses on the analysis and control of modular multilevel converter (MMC). The control structures used in the control of MMC are presented. Outer control loops of the converter such as output current, DC-link voltage, and power controls as well as inner control structures unique to the converter such as circulating current control and sorting algorithm based submodule voltage balancing are investigated. In addition, switching methods proposed for MMC are also described. These control and switchin...
Citation Formats
M. B. Salman and G. M. Güvensen, “On the Effects of PA Nonlinearities for Hybrid Beamforming Based Wideband Massive MIMO Systems,” 2020, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/69929.