Performance Comparison for Single-User and Multi-User Network MIMO Cellular Systems with Power Management

Round 1

Reviewer 1 Report

The paper presents a performance comparison of two multi-user network multiple-input multiple-output schemes with power management: a "single-user" (SU) scheme, where edge sectors of neighboring base stations are allocated different frequency bands and a "multi-user" (MU) scheme, where edge sectors receive the same band and interference is handled by joint pre-processing among base stations. For this purpose, power management methods are proposed in order to help raise the signal strength of users in the edge segments while preserving the performance of users in the center regions of the base stations. The schemes are thoroughly evaluated by simulation and it is shown that the MU scheme may yield more average per-user capacity while preserving a uniform data rate across the cell.

The paper is very well written and extremely carefully edited; I could not pinpoint any errors. It presents in the first two sections a clear exposition of the background of the work, the fundamental problem that is addressed, and the basic ideas and terminology. After a discussion of the mathematical background of the signal model and the preprocessing techniques, the core of the paper consists of Section 5 and 6 where the power management techniques are described and ultimately the simulation results are presented and interpreted in detail; on this basis, Section 7 gives clear conclusions about the relative merits of both schemes. The presented work is original in that no related literature seems to have addressed the problem investigated in this paper (under consideration of power management) so far. I thus recommend acceptance for publication.

As a very minor issue to be (optionally) addressed: Section 6 could say some words about how the simulation results were derived; also the corresponding data could be made publicly available.

Author Response

The authors are very grateful for the reviewer’s approval of our manuscript. According to your suggestion, we will publicly upload the source code and numerical data to our GitHub repository and its URL will be noted in the final version of our manuscript. 

Reviewer 2 Report

First, one remark related to ratings. In my ratings when "Average" is marked I mean that my opinion is rather "Good" or "Satisfactory". 

In general the paper is well written and touches an interesting topic associated with design of cellular systems based on the OFDMA multiple access method. The paper is well structured and shows some interesting results. However, I would expect that some more results can be easily contained in the paper. For example, how the simulation results would look like when the path loss coefficient \gamma is not 3 but it has a different value, e.g. 4 (a typical value). Would it have influence on numerical results presented in the simulation section? How did the authors select the proportion between central and edge parts of the cells? What is the justification of such a selection? The cell center part covers 3/4 area of the whole cell. How is it justified? Center parts of neighboring cells can easily interfere with each other. What happens if another proportion between these two parts is selected? Power optimization is somehow very simple. Are the algorithms presented in the paper the only possible ones? 

In Figs. 2 - 5 the markers should be improved. In the legends two types of triangle markers are denoted, whereas in the curves both look the same. One of them could be replaced, e.g. by circles. This would make the plots much more clear.  

As the authors could supplement their paper with some new results for different simulation parameters, I reccomend to accept the paper after major revision. 

Author Response

The authors appreciate very much the reviewers’ timely and detailed review. Please see the attachment for our point-to-point replies to your kind comments. The changes we have made in our newly submitted manuscript are appended in the end of our replies to the your comments.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors enriched their paper by showing the new results which I have asked for. At the moment the number of figures presenting plots is very high. Optionally, they could reduce it, but it is not necessary. The only thing which could be added is a short modification of the conclusion section, as it has been repeated from the original text, whereas some new results are included. 

Although the paper is written well, one can still find some very minor English errors (e.g. articles), so reading the paper by the native speaker is advised. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf