Two-Step Multiuser Equalization for Hybrid mmWave Massive MIMO GFDM Systems
, Pedro Pedrosa 1, Adão Silva 1, Rui Dinis 2 and Atílio Gameiro 1Round 1
Reviewer 1 Report
The work is devoted to requirements, which are placed on new mobile communication technologies. It is focused at higher data transfer speed, higher reliability of services, etc. It is based on new supportingand key technologies, like wide band mmWave RF chains and massive mMIMO antenna systems. To overcome a large number of problems with RF chains the use of new hybrid analog-digital architecture is considered. In which the mmWave RF chains and mMIMO systems are very important. The authors are presenting the system of hybrid mmWave and mMIMO with usage of GFDM as a two-step multi-stage balancing devices. This is considered in the first step ofdesign of analogue part of equalizer and in a second step of design of digital part of equalizer. The design of the wireless transmission chain is presented very comprehensively, including both a transmitter with a precoder and a receiver with an equalizer. For the analysis of the article it is possible to use the block diagrams of transmitter and receiver, the theoretical interpretation of the problem and on the simulations of the performance comparison of the designed hybrid precoders.
The strong part is the explanation of the reason for placing the article into the previous works, conceived on hybrid architectures and on GFDM. (Chapters 1.1 and 1.2) Among the strong chapters of the article we can assign a mathematical interpretation of the transmitter model (chapter 3.1) and the receiver model (chapter 4.1). This also includes (Chapter 5) modellingthe results of performance comparison of the proposed hybrid precoders. The fact that the whole work is only in the theoretical level, even if it is based on simulation, can be considered as a certain weakness of the article. However, this does not invalidate the importance of the work, It´s only the opinion of reviewer.
Author Response
Dear all,
Please see the attachment.
Yours Sincerely,
The authors
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper is well written and proposed scheme is interesting. Reviewer has the following major comments:
- Since authors have claimed that they have proposed a two-step hybrid multi-user (MU) equalizer combined with low complexity hybrid precoder for wideband mmWave mMIMO systems, Reviewer wants to see the complexity analysis in terms of flops . Authors can refer and cite "Transceiver Design for Energy-Efficiency Maximization in mmWave MIMO IoT Networks," in IEEE Transactions on Green Communications and Networking, vol. 4, no. 1, pp. 109-123, March 2020.
- All the simulation results presented in this paper is for MIMO system. However, authors have considered Massive MIMO GFDM Systems, hence, they must consider higher number of antennas such as 128, 256, etc., and demonstrate the performance of the proposed scheme.
Author Response
Dear all,
Please see the attachment.
Yours Sincerely,
The authors
Author Response File: Author Response.pdf
Reviewer 3 Report
This paper proposed a two-step hybrid multi-user equalizer combined with low complexity hybrid precoder for wideband mmWave mMIMO systems. The manuscript is well organized. However, there are some problems which lower the contribution of this work. Detailed comments are given as follows: 1. Some abbreviations, such as “RF, UT, SC-FDMA, QAM, AoD, ULA” should be given their full names when they first appear. 2. For the same word or abbreviation, the author should pay attention to use a unified format throughout the paper, such as “multi-carrier and M-QAM”. The author uses “multi carrier” in line 73, but “multi-carrier” in line 75, and “MQAM” is used in line 241, “M-QAM” is used in line 352. 3.In the line 210 of the paper, there is a predicate missing after “and $N_{ray}$”, and the author may consider modifying the sentence to “$N_{ray}$ denotes the number of paths per cluster”. 4. In this paper, the author assumes that “the analog equalizer is constant over the subcarriers due to hardware constraints”, the justification of which should be concisely demonstrated. And would this assumption lower the contribution of the paper. 5. There is a format error in line 233, and the author needs to confirm whether there are extra spaces in front of “This”.Author Response
Dear all,
Please see the attachment.
Yours Sincerely,
The authors
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Reviewer does not have any further comments.
