ELAA Channel Characterization with Parameter Estimation Based on a Generalized Array Manifold Model

Round 1

Reviewer 1 Report

This paper introduces a generalized array manifold model to estimate the channel of extremely large antenna arrays. The proposed GAM-SAGE outperforms the SP-SAGE in terms of reproducing the spatial consistence. Measurement results also verify the effectiveness of the model. Overall, the paper is interesting and well-written. I recommend the publication of the paper.

A typo in line 36, “componentss” should be “components”.

Author Response

Thank the reviewer for the comments. We have addressed all the comments from the reviewers and editor. We upload a PDF file including the final revised version of the manuscript, a revised version of the manuscript with highlighted modification, and a Response Letter. Please check the attachment.

Thank again for the work of the editor and reviewers.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper proposes an algorithm to estimate the channel parameters, with a specific reference to the angular domain, when large antenna arrays are adopted in the millimeter-wave context. The algorithm, called generalized array manifold (GAM) - Space-Alternating Generalized Expectation maximization (SAGE), is used to characterize actual propagation scenarios. The presented solution is experimentally checked and the achievable performance is compared to that of the existing specular path technique. The work is well written and organized, while the provided research contribution is relevant. Thus, in the referee's opinion, the work deserves publication and just some minor issues may be addressed. These issues are listed in the following of this review.

1) A formal definition of the channel similarity index would help to clarify the significance of Fig. 6.

2) Since the SAGE algorithm is one of the topics of the proposed work, a more extended literature overview concerning this technique would be appropriate, also because along the years, several papers have improved its functionalities. See, for example: (i) “Joint detection estimation of directional channel parameters using the 2-D frequency domain SAGE algorithm with serial interference cancellation,” IEEE Int. Conf. Commun., 2002; (ii)  “Sparse variational Bayesian SAGE algorithm with application to the estimation of multipath wireless channels,” IEEE Trans. Signal Process., 2011; (iii) “Multi-band time of arrival estimation for Long Term Evolution (LTE) signals,” IEEE Trans. Mobile Comput., 2021; and others.

3) Fig. 7 should be enlarged, since the writings inside it a are difficult to read.

4) Some typing errors are present along the text, such as in the line before eq. (16), and should be corrected.

Author Response

Thank the reviewer for the comments. We have addressed all the comments from the reviewers and editor. We upload a PDF file including the final revised version of the manuscript, a revised version of the manuscript with highlighted modification, and a Response Letter. Please check the attachment.

Thank again for the work of the editor and reviewers.

Author Response File: Author Response.pdf