======= Review 1 ======= *** Strong Aspects: Comments to the author: What are the strong aspects of the paper? This paper analyses the placement of virtualized core functions co-located with BSs in the radio access networks with the constraints of limited backhaul. This analysis includes a comparison of centralized and distributed placement strategies, with respect to the overall backhaul bandwidth consumption. The main result derived from this analysis is that distributing instances of the core functions in the network is significantly less costly from a backhaul point of view. *** Weak Aspects: Comments to the author: What are the weak aspects of the paper? This paper does not consider how the wireless channel response affects the association of the UEs. *** Recommended Changes: Recommended changes. Please indicate any changes that should be made to the paper if accepted. This paper has an acceptable structure, however the language needs improvement including better quality figures. *** Relevance and Timeliness: Rate the importance and timeliness of the topic addressed in the paper within its area of research. Good. (4) *** Technical Content and Scientific Rigour: Rate the technical content of the paper (e.g.: completeness of the analysis or simulation study, thoroughness of the treatise, accuracy of the models, etc.), its soundness and scientific rigour. Valid work but limited contribution. (3) *** Novelty and Originality: Rate the novelty and originality of the ideas or results presented in the paper. Some interesting ideas and results on a subject well investigated. (3) *** Quality of Presentation: Rate the paper organization, the quality of text, English, and figures and the completeness and accuracy of references. Well written. (4) ======= Review 2 ======= *** Strong Aspects: Comments to the author: What are the strong aspects of the paper? This paper focuses on the Local CN functions placement problem within a network of multiple interconnected BSs. It is an interesting proposal and overall technically sound. *** Weak Aspects: Comments to the author: What are the weak aspects of the paper? Maybe, in "Po" case, the total bandwidth consumed on each link by the signaling between MME and S-GW should give a generic model where possible, rather than according to the given network topology. *** Recommended Changes: Recommended changes. Please indicate any changes that should be made to the paper if accepted. There are some problems with the paper. (1) The figure 7 is not clear. It requires some improvements to the legend of the color and performance curves: it has overlapping elements and be blurry. (2) Some citation errors: such as "…passing through the only S-GW at j5 (Fig. 4)". The "Fig.4" should be "Fig.3". *** Relevance and Timeliness: Rate the importance and timeliness of the topic addressed in the paper within its area of research. Good. (4) *** Technical Content and Scientific Rigour: Rate the technical content of the paper (e.g.: completeness of the analysis or simulation study, thoroughness of the treatise, accuracy of the models, etc.), its soundness and scientific rigour. Valid work but limited contribution. (3) *** Novelty and Originality: Rate the novelty and originality of the ideas or results presented in the paper. Some interesting ideas and results on a subject well investigated. (3) *** Quality of Presentation: Rate the paper organization, the quality of text, English, and figures and the completeness and accuracy of references. Well written. (4) ======= Review 3 ======= *** Strong Aspects: Comments to the author: What are the strong aspects of the paper? This paper investigated the placement of virtualized core functions co-located with BSs in the radio access networks with the constraints of limited backhaul. Three optimization problems of minimizing the backhaul consumption are formulated with different placement strategies of MME entities. *** Weak Aspects: Comments to the author: What are the weak aspects of the paper? 1. The problem formulations for P1, PJ and P0 should be suitable for general scenarios rather than dedicated to the examples of Fig.3, Fig.4 and Fig.5. 2. The solutions to problems are given by the commercial solver "CPLEX" and how the authors confirm that the solutions are optimal? 3. In the section III-D, this paper considers an OFDMA-based system, with orthogonal channels allocated to the set of BSs, which is inconsistent with the current practical systems, because the eNodeB in the LTE systems reuse the spectrum resources. 4. This paper does not consider how the wireless channel response affects the association of the UEs. 5. This paper is poor written and unreadable. *** Recommended Changes: Recommended changes. Please indicate any changes that should be made to the paper if accepted. Please see the Weak Aspects. *** Relevance and Timeliness: Rate the importance and timeliness of the topic addressed in the paper within its area of research. Good. (4) *** Technical Content and Scientific Rigour: Rate the technical content of the paper (e.g.: completeness of the analysis or simulation study, thoroughness of the treatise, accuracy of the models, etc.), its soundness and scientific rigour. Questionable work with severe flaws. (1) *** Novelty and Originality: Rate the novelty and originality of the ideas or results presented in the paper. Minor variations on a well investigated subject. (2) *** Quality of Presentation: Rate the paper organization, the quality of text, English, and figures and the completeness and accuracy of references. Substantial revision work is needed. (2) ======= Review 4 ======= *** Strong Aspects: Comments to the author: What are the strong aspects of the paper? This paper focus on the deployment of local CN function inside the RAN to enhance the flexibility of future mobile networks. Different deployment strategies are considered and analysed. *** Weak Aspects: Comments to the author: What are the weak aspects of the paper? The quality of the figures could be enhanced. The size of the network is relatively small *** Recommended Changes: Recommended changes. Please indicate any changes that should be made to the paper if accepted. Please improve the quality of the figures *** Relevance and Timeliness: Rate the importance and timeliness of the topic addressed in the paper within its area of research. Good. (4) *** Technical Content and Scientific Rigour: Rate the technical content of the paper (e.g.: completeness of the analysis or simulation study, thoroughness of the treatise, accuracy of the models, etc.), its soundness and scientific rigour. Valid work but limited contribution. (3) *** Novelty and Originality: Rate the novelty and originality of the ideas or results presented in the paper. Some interesting ideas and results on a subject well investigated. (3) *** Quality of Presentation: Rate the paper organization, the quality of text, English, and figures and the completeness and accuracy of references. Well written. (4)