Deep unfolded extended conjugate gradient method for massive MIMO processing with application to reciprocity calibration

Sirois, S., Ahmed Ouameur, M. et Massicotte, D. (2021). Deep unfolded extended conjugate gradient method for massive MIMO processing with application to reciprocity calibration. Journal of Signal Processing Systems, 93 (8). pp. 965-975. ISSN 1939-8115 DOI 10.1007/s11265-020-01631-1

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Résumé

In this paper, we consider deep unfolding the standard iterative conjugate gradient (CG) algorithm to solve a linear system of equations. Instead of being adjusted with known rules, the parameters are learned via backpropagation to yield the optimal results. However, the proposed unfolded CG (UCG) is extended wherein a scalar parameter is substituted by a matrix-parameter to augment the degrees of freedom per layer. Once the training is completed, the UCG has revealed to require far a smaller number of layers than the number of iterations needed using the standard iterative CG. It is also shown to be very robust to noise and outperforms the standard CG in low signal to noise ratio (SNR) region. A key merit of the proposed approach is the fact that no explicit training data is dedicated to the learning phase as the optimization process relies on the residual error which is not explicitly expressed as a function of the desired data. As an example, the proposed UCG is applied to solve the reciprocity calibration problem encountered in massive MIMO (Multiple-Input Multiple-Output) systems.

Type de document:	Article
Mots-clés libres:	Deep unfolding Conjugate gradient Massive MIMO Reciprocity calibration Least squares
Date de dépôt:	09 mai 2022 14:47
Dernière modification:	09 mai 2022 14:47
Version du document déposé:	Post-print (version corrigée et acceptée)
URI:	https://depot-e.uqtr.ca/id/eprint/10123

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