Energy Efficiency Maximization for Hybrid-Powered 5G Networks with Energy Cooperation
Round 1
Reviewer 1 Report
The paper presents a method of increasing the energy efficiency of hybrid powered 5G networks using optimization algorithms. The paper is well written.
Author Response
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Reviewer 2 Report
This paper studies the resource allocation problem of energy efficiency maximization. Considering the QoS constraints of UEs, power constraints of cellular base stations and renewable energy harvesting constraints, three problems of user association, power allocation and energy cooperation are jointly optimized.
The authors propose a fixed variable iterative algorithm, which uses Lagrange dual method, improved particle swarm optimization method and matching algorithm to solve these three subproblems.
The article is well written, easy to follow and to understand. The proposed approach is analyzed with all intermediate steps.
The bibliography is well given. It could be enriched by incorporating recent references from the MDPI as well.
The methodology is sufficiently demonstrated. The authors have included the system model, problem formulation and constraints for the design of their method.
The authors have made a detailed analysis, and the presentation is at a good level.
The purpose of the paper and the research findings are clear and relatively concise. The figures illustrate the value of the proposed model in the experiments.
The conclusions could state what uncertainties and limitations remain that could be solved in future extensions of the study. Also, the authors could discuss the advantages and the possible broad applicability and scope of the proposed algorithm except for the current problem addressed here.
In an Appendix section, the authors should give a glossary of variables used in this paper.
Author Response
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Reviewer 3 Report
The paper aims to improve the energy efficiency of a downlink transmission of a dense 5G system by integrating both renewable energy (RE) and energy harvesting (EH) techniques into the 5G systems. The problems have been decomposed into three different levels. The research challenge is relevant and crucial while the approach offers an extension of the previous knowledge done in this field. However, it is suggested that the authors perform several more improvements to enhance the clarity of the manuscript, as below:
- In Section 2, the authors assume the channel fading as large scale, but since the focus is on small-cell, how valid are the assumptions, considering in a dense small-cell 5G deployment with mm-Wave, the presence of scatterers and multipath is more dominant than path loss/shadowing? Also later in Section 4, the authors mentioned both small and large scale fading - why the inconsistency?
- As a continuation of the previous concern, please specify the path loss models and several other simulation parameters related to the large scale fading in this study
- Each of the constraints under Eq(7) can be improved by including a short text to explain each of the constraints, i.e. C3 (QoS) and so on. Also, unclear on the difference between C1 and C2, C4 and C6 - require further explanation to support the equation.
- It is understood that the authors considered the mm-Wave environment, however, such information is missing in Table 1 and Section 4. The BS Tx power - is it based on mm-Wave base station? If yes, include relevant tech specs, e.g. 3GPP, telco equipment to support the representation
- It is understood that the paper assumes both RE and EH separately. However, in Section 4, it is only mentioned that the EH is between 30-40 dBm. Where is the RE? Or does the EH include both RE and EH? Also, please elaborate on what kind of EH technique that capable of producing such a large value assumed in this study.
- Reference 12 (http://www.huawei.com/en/about-huawei/publications/communi-655 caite/hw-082734.htm) could not be accessed at the time of review. Please fix the link
Finally, please improve and fix a few typos, grammar errors and inconsistent representation of vectors in non-italic across the manuscript.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
The research is significant and well presented.
Some typos and gramatical errors should be corrected. The proofreading is recommended.
Author Response
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