Hierarchical Multi-Blockchain Architecture for Scalable Internet of Things Environment

Round 1

Reviewer 1 Report

Authors proposed an interesting approach based on blockchain and to be applied on IoT scenarios (e.g., the one mentioned in the manuscript, car rental services), together with an overall good methodology presentation and with results supporting their proposal. Nevertheless, it has to be remarked that readers may not be able to fully understand the approach proposed by authors due to the fact that ALL figures are missing in the submitted manuscript, hence many concepts mentioned in the text and referencing these figures may be of difficult understanding. Please include them in the revised version of the manuscript.

Author Response

First of all, we would like to thanks the anonymous reviewers for their insightful comments.
The manuscript has been updated following the reviewers' suggestions.
Below is the summary of changes:

- The abstract is mostly changed and extended.
- Add all of the figures that were missing in the previous manuscript.
- Minor fixes in the caption of figure 10.
- Minor fixes in the caption of figure 11.
- Minor grammar fixes in the following lines*:
53, 55, 74, 117, 427, 429, 430, 453, 469, 489, 491, 605, 669, 752, 778, 885

Other changes not related to the contents of the paper are as follows:
- Add one new author and the respective contributions.
- Add a new source of funding.
- The authors' affiliation is changed.

* These lines are numbers of lines in the updated manuscript.

Reviewer 2 Report

The authors propose a scalable two-tiered hierarchical blockchain architecture for IoT.

The paper is well written and is scientifically sound. The authors thoroughly described their contribution to the field.

Considerations to be addressed by the authors:

1- I believe the Abstract is excessively summarized. The authors could expand it more.

2- Where are the figures? They are missing!

Author Response

First of all, we would like to thanks the anonymous reviewers for their insightful comments.
The manuscript has been updated following the reviewers' suggestions.
Below is the summary of changes:

- The abstract is mostly changed and extended.
- Add all of the figures that were missing in the previous manuscript.
- Minor fixes in the caption of figure 10.
- Minor fixes in the caption of figure 11.
- Minor grammar fixes in the following lines*:
53, 55, 74, 117, 427, 429, 430, 453, 469, 489, 491, 605, 669, 752, 778, 885

Other changes not related to the contents of the paper are as follows:
- Add one new author and the respective contributions.
- Add a new source of funding.
- The authors' affiliation is changed.

* These lines are numbers of lines in the updated manuscript.