A Long-Range Signal-Based Target Localization Algorithm

Round 1

Reviewer 1 Report

Authors present a device-less target localization algorithm based on LoRa technology.

Some comments are presented in the following:

·         Abstract Section could be improved.

·         Introduction and some Background should be better supported in References.

·         Review on line 42 “millimetre”.

·         Paragraph from lines 91 to 100 must be improved in order to make it more comprehensible.

·         Check on line 101 “modelled”

·         Check on line 212 “signal . Upon”

·         Descriptions of Equations (2) and (3) are plenty of errors. From line 219 to 231 are variables that does not appear in the text (blank spaces).

·         In general, all the Equations must be rewritten in a more scientific form and format. The same for the description of the Equation variables. Many variables are missing or not described/explained. Review this for all the document.

·         Figure 1 is not mentioned/explained in the text.

·         The arrows in Figure 3 may be better positioned.

·         Format of variables of Eq 4 on line 301

·         Description of Figure 5 could be improved. It also lacks of axes units.

·         The explanation of Equations 9 and 10 could be improved (Section 4.4). From Eq 10 there are variables that are not described.

·         A Figure can help to improve explanation of Section 4.5

·         In Section 4.6 it is not clear what the different K sources of the received signals are.

·         In Section 5.1, and for all the document, check if the references correspond to the cited ones. For instance, the Reference for WiTraj seems to be 21 instead of 20. Verify the consistency of all references.

·         For evaluation of Section 5.1 a comparison in terms of complexity of consuming time of each algorithm is missing.

·         In line 471 must be Table 2 instead of “the table below”

·         For all the evaluations there is no information about the number of measurements or confidence intervals.  

·         Why all the evaluations were done for 1 m walking distance, could be included more values?

·         Figure 9 is not referenced, mentioned or explained in the text.

·         For Section 5.4 Tx-Rx distance, is there a point at which a greater distance implies a greater error?

·         Figure 10 is not referenced, mentioned or explained in the text.

·         Equation on line 580 should be better as a regular Eq.

·         Caption of Figure 13 does not correspond to it.

·         Discussion Section could be extended and complemented

Overall english quality could be improved.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper presents a method for indoor location estimation based on phase-shift detection. The method is novel and the evaluation is adequate. There are only some minor corrections recommended, which could improve the clarity of the paper.

The description of localization problems, provided in the paragraph starting in line 59 on page 2, starts with the reference to "device-less localization", but the whole paragraph describes localization of a wireless device. Additionally, there are multiple statements on problems with fingerprinting, limited scalability of Doppler-based techniques, etc. which are not supported by references to the literature. References to the works which justify the opinions provided in the introduction should be added.

The method of adding reference at the end of a sentence, while citing the names of the authors at the beginning (e.g. line 128, 137) is hard to follow. The references should be added right after the names of the authors.

The description in section 4.5 on how the angle of arrival is converted into a position is not fully clear. There is no direct description of the method used to calculate the distance between the transmitter and the receiving antenna array. Sections 4.6 and 4.5 provide some data on how the possible target positions are estimated, but the description is not precise enough. A pseudocode or a more precise formulation of the algorithm would be beneficial for the reader.

The experiments are well planned and it's good that experiments with different persons and different types of walking are included. However, there is too little details given on how the experiments were performed - how many measurements have been gathered for each CDF plot? how was the ground knowledge collected (how was the actual location of the person during the walk estimated), how long was the transmission and how many packets were collected to establish the location?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper presents an experimental investigation of a LoRa-based target localization algorithm, which relies on antennas' sensing capabilities to capture the phase change of the signal ratio from the signal amplitude. However, the following corrections are recommended before the paper can be considered for publication:

 1. The experiment was conducted for a walking distance of only 1 meter, which is not representative of realistic scenarios. Therefore, it is recommended to extend the trajectory length.

 2. Does the proposed localization method, particularly in Section 5.5, account for the co-existence of multiple targets? A clarification on this aspect is necessary.

3. The proposed method exhibits lower accuracy (0.46 m) in indoor environments compared to outdoor environments (achieving 0.45 m). However, the introduction emphasizes the greater demand for indoor localization due to the challenges of GPS coverage indoors. Therefore, an accuracy comparison with other technologies such as GPS, mmWave, and visible light communication localization methods is recommended.

 4. Although the paper includes a discussion section as a conclusion, the addition of a separate conclusion section is essential.

 5. In-text citations of references are not organized in order of appearance. It is necessary to rearrange the references in accordance with their appearance in the text. Additionally, a discussion of references in Table 1 within the body text of Section 2 is required. Additionally, the reference list needs to be revised to comply with the standard format.

 6. Clear definitions of all parameters used in the equations are necessary.

 7. Revision and proofreading are required to eliminate repetition and redundancy. For instance, Section 4.1 can be omitted as subsequent sections provide detailed explanations of the concepts. Similarly, statements between lines 288 and 289 are repeated with different wording in lines 290-291. Such redundancies should be addressed to enhance the clarity and coherence of the paper.

Review the manuscript for grammar and language mistakes.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors have addressed all necessary corrections to the satisfactory standard.