Hybrid Beamforming Structure Using Grouping with Reduced Number of Phase Shifters in Multi-User MISO

Comments 1: In the abstract, there is no information about the adopted methodology. one or two sentences may be included.

Response 1: Owing to your indication, we added the sentence of the methodology used in the proposed method in the abstract. This change can be found at line 8-9, paragraph Abstract, page number 1 in the revised manuscript.

Comments 2: Provide the detailed term of "MRT" at the first appearance of the acronym in the paper.

Response 2: In the revised paper, we added the detailed term of "MRT". This modification can be found at line 67-68, paragraph System Model, page number 2 in the revised manuscript.

Comments 3: A literature survey that investigates the previous studies in the same field is highly advised to be included in the introduction.

Response 3: Thank you for pointing this out. we agree with this comment. Therefore, we added the content of the previous studies in the same field. This modification can be found at line 38-47, paragraph Introduction, page number 1-2 in the revised manuscript.

Comments 4: A comment about the effect of the antenna selection on the performance in the light of the results obtained in Figures 6 and 7 may be important to include in the discussion.

Response 4: Thank you for pointing this out. We agree with this comment. Therefore, we added the sentence about the effect of the antenna selection on the performance in the light of the results obtained in Figures 6 and 7. This modification can be found at line 208-214, paragraph Comparison, page number 8 in the revised manuscript.

Comments 5: If available to provide a table of comparison at the end of the paper to highlight the advancements proposed by this work in comparison to other related works, it will be good.

Response 5: Thank you for pointing this out. But we are sorry that we can't output the results of other related works and add them to the paper.

Comments 6: It is stated in the abstract that "Simulation results show that the proposed scheme can reduce the number of phase shifters used on the transmit side compared to the conventional HBF scheme while maintaining sum-rate performance". According to the conclusion, "there is a trade-off between the reduction in the number of phase shifters used to form the beam and the improvement in performance as the number of transmit antennas increases". It is important to refer to such a trade-off in the abstract sentence.

Response 6: Thank you for pointing this out. We agree with this comment. Therefore, we added the sentence of the trade-off between the reduction in the number of phase shifters used to form the beam and the improvement in performance. This change can be found at line 12-14, paragraph Abstract, page number 1 in the revised manuscript.

Comments 7: The list of references needs to be supported by some of recent references in the same field of study.

Response 7: Owing to your comments, we have added references with the content added as previous studies in the Introduction. This change can be found-page number 10, paragraph References, and line 242-245.

4. Response to Comments on the Quality of English Language

Point 1: English language fine. No issues detected.

Response 1: Thank you for taking the time to correct the English in this paper.

5. Additional clarifications

Comments 1: In line 94-95, this sentence “In (11), the first term (hk,i fi,k) is real and the phase component of each element of the second term (hk,l fl,j) is different.” does not make sense or should be corrected. Does it mean that the first term is the inner product of conjugate quantity (desired signal) while the second (the interference signal) is not, that is while the first is real and analytically larger than the second?

Response 1: Thank you for pointing this out. We agree with this comment. Therefore, we changed the sentence to a rewritten version base on your advise. This modification can be found at line 120-122, 142-144, paragraph Proposed Scheme, page number 4, 6 in the revised manuscript.

Comments 2: For the kernel transmitting matrix H, the author uses a Rayleigh flat fading and the noise configuration of Gaussian distribution. Is there any specific reason for that? Have you tried to test your model under other conditions to prove its versatility?

Response 2: Thank you for pointing this out. We agree with this comment. Therefore, we added the reason for the channel model and noise configuration as in the paper. This change can be found at line 167-174, paragraph Comparison, page number 7 in the revised manuscript.

Comments 1: The BER could be also a term of performance evaluation.

Response 1: Thank you for pointing this out. We agree with this comment. However, since the performance of HBF was compared by sum-rate in most of the papers, we also compare the conventional and proposed methods by sum-rate in this paper.

Comments 2: The state of the art is summary presented. The authors should expand the literature review to include more recent advancements and alternative approaches in the field.This would provide a more comprehensive context and the novelty and original elements would be highlighted.

Response 2: Thank you for pointing this out. we agree with this comment. Therefore, we added the content of the previous studies in the same field. This modification can be found at line 38-47, paragraph Introduction, page number 1-2 in the revised manuscript.

Comments 3: The paper identifies the challenge of reducing hardware complexity in HBF structures but does not sufficiently address how these impacts other aspects of system performance, such as energy consumption or computational complexity.

Response 3: Thank you for pointing this out. we agree with this comment. Therefore, we added sentence of antenna selection impact on communication efficiency and received signal improvement. This modification can be found at line 182-186, paragraph Introduction, page number 7-8 in the revised manuscript.

Comments 4: The references are relevant, but the list iv very short for a journal original article.

Response 4: Owing to your indication, we added some references. This change can be found at paragraph References, page number 10 in the revised manuscript.

Comments 5: The description of analog and digital beamforming could be expanded to clarify the limitations of each technique.

Response 5: Owing to your indication, we added the sentence explaining the characteristics of ABF and DBF in next generation communications. This change can be found at line 25-38, paragraph Proposed Scheme, page number 1 in the revised manuscript.

Comments 6: The explanation of how the proposed method reduces the number of phase shifters by selecting antennas with the highest gain is somewhat vague.

Response 6: Owing to your indication, we added the sentence explaining specifically how much the number of phasors has changed between the conventional and proposed methods. This change can be found at line 109-111, 129-131, paragraph Proposed Scheme, page number 4, 5 in the revised manuscript.

Comments 7: All acronyms should be explained at their first used.

Response 7: In the revised paper, we added the detailed term of "MRT". This modification can be found at line 67-68, paragraph System Model, page number 2 in the revised manuscript.