Radar and Communication Spectral Coexistence on Moving Platform with Interference Suppression

Round 1

Reviewer 1 Report

In this paper, the MM-ADMM algorithm is proposed for radar & communication spectral coexistence system. Under the constraints of constant modulus, similarity and energy, and based on the criteria of maximizing the communication rate and radar signal-to-interference-noise ratio, the communication codebook, transmit waveform and receive filter weight are optimally designed to obtain Better mutual ambiguity function performance, SINR performance and communication rate performance. The paper is well-organized and easy to follow. Please find my comments as follows.

- Figure 3 shows the convergence curve of the residual norm of the auxiliary variable with the number of iterations. The feasibility tolerance of each constraint can be added for comparison, so as to better explain that the algorithm satisfies the stopping condition;
- You can refer to equation (3.12) in the following literature: [1] Boyd S , Parikh N , Chu E , et al. Distributed Optimization and Statistical Learning via the Alternating Direction Method of Multipliers[J]. Foundations & Trends in Machine Learning , 2010, 3(1):1-122.
- Figure 6 should be similar to Figure 4, with boxes or ellipses to indicate the location of the target and the interference, and the solid lines can be represented by different colors;
- There are also some existing works dealing with similar problems that might need to be mentioned:
   Z. Cheng, C. Han, B. Liao, Z. He and J. Li, "Communication-Aware Waveform Design for MIMO Radar With Good Transmit Beampattern," in IEEE Transactions on Signal Processing, vol. 66, no. 21, pp. 5549-5562.
   Ningkang Chen, Ping Wei, Lin Gao, Huaguo Zhang. Beampattern synthesis and spectral compatibility based MIMO radar waveform design[J].Digital Signal Processing,Volume 118,2021.

Author Response

We would like to thank the reviewer for spending his/her time to assess this submission and are grateful for the reviewer’s affirmation of the organizational structure of this paper. In the attached file, we provide a point-to-point reply to the reviewer’s comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper presented a radar and communication spectral coexistence system on moving platform (vehicles) with interference suppression mechanism. Regardless of the interesting research issue, the paper cannot be accepted for publication in its current form. The reviewer hopes that the authors can resolve the following concerns for improving academic quality of the paper. 

1. The authors attempted to construct optimization problem to fulfill both the requirement of the communication and radar links. Via simulation, the optimization results could be achieved, globally in a centralized manner. The reviewer concerned that how the same mechanisms can be applied in realistic environments where the vehicles move independently and there should be no centralized entity to run and optimize these parameters. In other words, the proposed mechanism is not suitable for such moving platform where distributed controlling mechanism is required. 

2. Related to 1., since the vehicles are moving objects, the channel responses will be aging very fast. It is not clear if the optimized results are effective or not when the optimized parameters are applied in the deployment phase. Please elaborate this point. 

3. There is no discussion about the feasibility of the optimization problem. Do the authors guarantee optimized results should be always existed? 

4. Related to 3., if the optimization problem in some certain conditions are not feasible, do the authors guarantee that the SINR constraints for both communication links and radar links are satisfied or violated. Please elaborate this point. 

5. Related to 2., more numerical results in environments of dynamic variation of the fading channels should be added/evaluated to show the effectiveness of the proposed scheme in realistic environments.

Author Response

We would like to thank the reviewer for spending his/her time to assess this submission. In the file attached, we provide a point-to-point reply to the detailed comments made by the reviewer.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments to the authors:

1. My first concern is the significance of the proposed method. Please discuss the application of “Radar and Communication Spectral Coexistence” in more detail and provide a real-world example showing the need for that or give an example of a trend in technology that needs this coexistence in the future.

2. It is claimed that the topic is emerging “as an emerging topic, has attracted considerable attentions and yielded several literatures recently”. Please provide more references on that. Reference 4 is completely non-relevant to this topic. Reference 4 discusses the RFI mitigation in radiometry which means reducing the negative effect of the received signal from any source (including communication systems) other than the target under investigation in passive remote sensing and so there is no attempt for radar-communication system co-existence. Reference 4 does not discuss modifying the radar/radar signal and communication system to make both systems operable at the same time. In fact, in passive remote sensing there is no active radar. I have not checked the other references (5-7).

3. In section 5, add an illustration of the scenario considered for performance analyses. Lines 170 and 171 in page 16 are vague, please rewrite.

4. More thorough investigation of the method performance is required. Many assumptions in Section 5 have been made including the number of sensors, location/number of targets, and Doppler frequency. The performance of the method must be investigated versus different parameters. Without a thorough discussion on the method performance the paper cannot be accepted.

5. In section 5, it is only shown that the effect of communication system on the radar is suppressed. As the title of the paper suggests “Radar and Communication Spectral Coexistence”, performance of the communication system in presence of the radar must be also investigated. For example, please discuss what happens to BER of a communication system in presence of the radar with and without applying the method.

6.  Computational complexity of the method must be discussed.

 

Author Response

We would like to thank the reviewer for spending his/her time to assess this submission. In the file attached, we provide a point-to-point reply to the detailed comments made by the reviewer.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors' responses were not satisfiable for the reviewer in some aspects, the paper is not recommended for publication at this stage. 

Comment 1) The reviewer requested the authors to discuss whether the proposed mechanism is not suitable for such moving platform where distributed controlling mechanism is required, but no proper discussions were conducted. 

Comment 2) The reviewer did not understand how/where the manuscript was updated based on the comment.

Author Response

Dear Reviewer,

Thanks very much for the valuable ideas, time, and suggestions to improve the quality of the manuscript. According to the comments from reviewers, we have modified the draft to make it clearer. For the reviewers’ convenience, we illustrate our response to each single point in itemized form, using italic text for the comments from reviewers, regular text for our responses, and highlighting in red the changes we made in the revised manuscript.

Best

Le

Author Response File: Author Response.pdf

Reviewer 3 Report

I have no further comments.

Author Response

Dear Reviewer,

Thanks very much for the valuable ideas, time, and suggestions to improve the quality of the manuscript. According to the comments from reviewers, we have modified the draft to make it clearer. For the reviewers’ convenience, we illustrate our response to each single point in itemized form, using italic text for the comments from reviewers, regular text for our responses, and highlighting in red the changes we made in the revised manuscript.

Best

Le

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

Thanks the authors for the responses to the reviewer's comments. The responses were fine and the paper might be recommended for publication, knowing that as the paper stated, this paper assumed a centralized center who can gather all channel information of all links. Such assumption is fine but not feasible according to the reviewer. Especially, such information will be aging (not usable) due to time lag between the channel estimation phase / optimization phase and deployment phase. The reviewer wishes the authors discuss this issue in the future or mention about it in the future work. 

Author Response

Dear Reviewer,

Thanks very much for the valuable ideas, time, and suggestions to improve the quality of the manuscript. According to the comments from reviewers, we have modified the draft to make it clearer. For the reviewers’ convenience, we illustrate our response to each single point in itemized form, using italic text
for the comments from reviewers, regular text for our responses, and highlighting in red the changes we made in the revised manuscript.

Best

Le

Author Response File: Author Response.pdf