A Comparison of Blockchain Recovery Time in Static and Mobile IoT-Blockchain Networks
Round 1
Reviewer 1 Report
Authors present a comparison of different routing protocols in terms of recovery time when applied to iot blockchain networks. Although the topic itself could be of interest for the research community, because it addressed the problem of using blockchain technology in ioTs, the paper itself does not provide enough novelties respect to the previous author's published paper (see reference 12). In this new paper, authors have extended the study with one more routing protocol (BABEL) and a small mobile network.
The paper is well written, well structured and both the methodology and results are well presented.
my major concern is about the small novelty aported respect to previous presented paper. Besides, authors talk about complex mobile scenario that is emulated, but only nine nodes are emulated. I consider that a mobile network with just 9 nodes is not relevant.
The new evaluated routing protocol does not introduce new conclusions with respect to previous paper.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper performs a comparison of IoT-Blockchain operation over wireless ad-hoc networks using 3 different routing protocols: OLSR, BATMAN and BABEL
The writing is correct, and the paper is easy to read.
The paper describes the importance of ad-hoc networking in an IoT scenario. The problem statement is sound, introduction and related work motivate the research problem. References are timely and appropriate.
Numerical results are obtained using a real testbed and emulation through mininet. Numerical results are centered on throughput and delays when a disruption occurs in the connection path, and the routing protocol has to reestablish the connection. Both static and mobile nodes are considered. Results show that BATMAN outperforms the other protocols.
The weakest point of the paper is its originality. No new methods or algorithms are proposed.
To improve the interest of the paper I suggest e.g.:
- Describe a more specific use case for the blockchain operation. That is, the scenario analyzed in the paper corresponds to a generic blockchain transaction. The authors could be more specific to the scenario where the blockchain would be needed, and the conditions under which the transaction will occur
- Be more detailed in the numerical results. For instance, the recovery time is given by several components in equations (1)-(3). In the numerical results only the overall value is given. It would be interesting the have the value of each part (e.g. using stacked bars) to have better insight.
- Misleading sentence:
page 7: The sentence copied below is misleading. First the authors say "nine nodes" and then "both". Also saying that the SSID is "Sue" is irrelevant. Better remove "and both are in the range of an ad-hoc network with SSID (e.g., Sue)", it is clear that being ad-hoc all share the same SSID.
"...we create nine nodes to simulate IoT devices, which operate according to the IEEE 802.11g standard. None of them are connected to any routers, but their wireless cards are set to ad-hoc mode, and both are in the range of an ad-hoc network with SSID (e.g., Sue)"
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Authors have addressed all reviewer's suggestions and know, in my opinion, the paper has enough quality to be published in this journal.
Reviewer 2 Report
The authors have changed the paper including my suggestions. I have only the minor comment below, for which it is not necessary another review round.
Minor comment: Explain why the pure_blockchain time is significantly different between the routing protocols. In particular, why it is always smaller for BATMAN?
