Dear Mr. XX:

I am writing to you in regards to manuscript # Access-2018-00777 entitled "XXXX" which you submitted to IEEE Access.

In view of the criticisms of the reviewer(s) found at the bottom of this letter, your manuscript has not been recommended for publication in IEEE Access.  Unfortunately, we will not accept resubmissions of this article.

Thank you for considering IEEE Access for the publication of your research.

Sincerely,

Dr. Hui-Ming Wang
Associate Editor, IEEE Access
xjbswhm@gmail.com

Reviewer(s)' Comments to Author:

Reviewer: 1

Recommendation: Reject

Comments:
In this paper, the authors studied the XX. In general, the authors thinks that the proposed strategy is interesting. However, from the technique contribution point of view, the reviewer thinks that the achievable rate analysis is too simple, which can be easily obtained just following standard steps, without any challenges. Also, the simulation provided is too simple, the authors may need compared with some basic schemes to show the advantage of the proposed scheme. To enhance the contribution of this work, the authors can theoretically derive the performance improvement comparing other basic schemes, for example, the relay just performs purely AF or DF forwarding strategy.

Furthermore, the reviewer thinks that writing of this paper is poor. For example,
1) Line 30-32, right column page 2, the authors show the order of SINR with definition of the channels. This should be put after the eq. (1)
2) Line 26-28, left column page 3, “we can see that if the transmit power for signal xe is not much higher than that for signal xb, xb can be seen as a strong signal to xe.” This sentence is confused.
3) At the sentence before eq. (9), Appendix I should be Appendix A.

Based on the above comments, the reviewer cannot recommend an acceptance of this paper.


Additional Questions:
Does the paper contribute to the body of knowledge?: A little

Is the paper technically sound?: A little

Is the subject matter presented in a comprehensive manner?: Yes

Are the references provided applicable and sufficient?: Yes


Reviewer: 2

Recommendation: Reject

Comments:
I do not recommend the acceptance of this paper for several reasons:
1) In Section II, it is said “Without loss of generality, we assume the average received SNR of x_b is greater than that of signal x_e at the relays and the received SINR of signal x_b at each relay is different”. Actually, I think that the first part of the assumption is not justified since we are considering fading channels and it could happen that the channel between S_e and one of the relays is better than the channel between S_b and this relay. Furthermore, this assumption is actually not needed at all. We can optimize the system performance even of this assumption is invalid.
2) The system performance is not optimized by any means. Furthermore, no objective function is defined to evaluate the performance of the system and to decide the relative importance of the BMS and EMS signals.
3) Why do the DF relays send only the BMS signal? If the DF relay has good channel, it may decode the EMS signal as well and send both signals together, subject to optimization. Since the DF relays have stronger source-relay channels, they are intuitively better than the AF relays, and hence they are more effective in sending the EMS signal than the AF relays which are prone to noise.
4) Let’s assume this ideal scenario. All instantaneous channels between the S_b source and the relays are strong. So, all relays will be able to decode the signal. So, all relays will be DF and no AF relays. This means that the users will not receive the enhancement layer because it will not be sent at all, despite the fact that the relays are in perfect channel conditions. This means that the system gets penalized by having good channel conditions! This is not a proper design.  
5) The literature survey is not exclusive. For example, there is a number of publications by Mohamed Attia et al on layered transmission over DF and AF relays.


Additional Questions:
Does the paper contribute to the body of knowledge?: The contribution of this paper is minimal.

Is the paper technically sound?: There are a number of technical concerns. Please refer to my comments to the authors.

Is the subject matter presented in a comprehensive manner?: No. There are many ambiguities and unjustified statements in the paper.

Are the references provided applicable and sufficient?: No. Some highly relevant publications are missing.


Reviewer: 3

Recommendation: Reject

Comments:

1. Almost the references in this paper are not new. Indeed, the related works such as [4]-[7] were published before 2012.

2. The HDAF methods were said many times before. Therefore, this paper is an extension of the previous works (see [4]-[8]).

3. The implementation of the protocols is very complex and not feasible for practical systems.

4. There is no performance evaluation for the proposed method, i.e., the authors did not provide expressions or formulas to evaluate the system performance.

Additional Questions:
Does the paper contribute to the body of knowledge?: Maybe

Is the paper technically sound?: No

Is the subject matter presented in a comprehensive manner?: Yes

Are the references provided applicable and sufficient?: No 返回小木虫查看更多