======= Review 1 ======= > *** Strong Aspects: Comments to the author: What are the strong aspects of the paper? The facilities layer-based mechanisms for information propagation are proposed and are shown to outperform classical network layer solutions. The proposed intelligent facilities layer mechanisms can result in a much shorter dissemination delay by reducing the number of redundant DENM transmission. The motivation and improtance of the problem are presented clearly. The results seem interesting and correc. > *** Weak Aspects: Comments to the author: What are the weak aspects of the paper? Some comments are listed for the reference. 1. The reviewer expect to read the complexity comparison between the proposed scheme and previous architectures. 2. About the proposed sheme, some thoretical derivations are preferred to solid the work. 3. All the figures are not plotted clearly, e.g. the Y axis of Fig. 1 can be adjusted to make it more readable. > *** Recommended Changes: Recommended changes. Please indicate any changes that should be made to the paper if accepted. Some comments are listed for the reference. 1. The reviewer expect to read the complexity comparison between the proposed scheme and previous architectures. 2. About the proposed sheme, some thoretical derivations are preferred to solid the work. 3. All the figures are not plotted clearly, e.g. the Y axis of Fig. 1 can be adjusted to make it more readable. > *** 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. Significant original work and novel results. (4) > *** Quality of Presentation: Rate the paper organization, the clearness of text and figures, 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 addresses the safety information dissemination problem in VANETs. It proposes facilities layer-based mechanisms for such information propagation. The aim of the paper is to present new mechanisms for information dissemination in VANETs, whose operation rely on the use of the standardized facilities layer. Numerical results show that the proposed approach is able to reduce information propagation delay in different vehicular density scenarios by means the number of transmitted messages (i.e., reducing channel congestion). > *** Weak Aspects: Comments to the author: What are the weak aspects of the paper? Although the introductory part of the paper gives to the reader a very good perspective of both non-safety application and particularly traffic safety ones, in order to improve the reading of the paper, Section I can be cut short without losing the main arguments. The same happens with Section II where authors describe the facilities layer (in this section, a diagrammatic representation of facilities layer will be good). Furthermore, authors state that this is the first time vehicular safety information dissemination in VANETs is evaluated in a “realistic context”. If this is the case, Section V should clearly state the main differences of the considered simulation setup with respect to previous studies found in the literature. On the other hand, it is difficult to follow the explanation of the proposed intelligent dissemination (Section IV). Therefore, to improve such aspects authors can: (1) place Figure 1 in the same page of the explanation; (2) clearly state at the beginning of this section the improvements proposed with respect to the standardized solution; (3) similarly, should provide details about the adaptation of the facilities layer to the proposed mechanism; (4) this section combines explanation of the proposed mechanism and also discussed in some parts previous mechanisms found in the literature (e.g., “previous research studies propose to base the dissemination process at the network layer. In this case, the possible forwarders have access to layer 3 information, such as the…”), which from my point might confuse the reader. With this regard, discussion of related work should be placed in Section II. The proposed mechanisms are evaluated in different vehicular density scenarios (Fig. 2), which is a good metric as the paper evaluates propagation information for a particular application (i.e., dissemination of safety information). However, one cannot find a reference value (delay requirement) to be satisfied by the proposed mechanisms. Furthermore, a benchmark mechanism should be considered in this section as well. > *** Recommended Changes: Recommended changes. Please indicate any changes that should be made to the paper if accepted. In order to improve the reading of the paper, Section I can be cut short without losing the main arguments. The same happens with Section II where authors describe the facilities layer (in this section, a diagrammatic representation of facilities layer will be good). Furthermore, authors state that this is the first time vehicular safety information dissemination in VANETs is evaluated in a “realistic context”. If this is the case, Section V should clearly state the main differences of the considered simulation setup with respect to previous studies found in the literature. It is difficult to follow the explanation of the proposed intelligent dissemination (Section IV). Therefore, to improve such aspects authors can: (1) place Figure 1 in the same page of the explanation; (2) clearly state at the beginning of this section the improvements proposed with respect to the standardized solution; (3) similarly, should provide details about the adaptation of the facilities layer to the proposed mechanism; (4) this section combines explanation of the proposed mechanism and also discussed in some parts previous mechanisms found in the literature (e.g., “previous research studies propose to base the dissemination process at the network layer. In this case, the possible forwarders have access to layer 3 information, such as the…”), which from my point might confuse the reader. With this regard, discussion of related work should be placed in Section II. The proposed mechanisms are evaluated in different vehicular density scenarios (Fig. 2), which is a good metric as the paper evaluates propagation information for a particular application (i.e., dissemination of safety information). However, one cannot find a reference value (delay requirement) to be satisfied by the proposed mechanisms. Furthermore, a benchmark mechanism should be considered in this section as well. > *** 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. Significant original work and novel results. (4) > *** Quality of Presentation: Rate the paper organization, the clearness of text and figures, 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? 1. Authors propose facilities layer-based mechanisms for information propagation. It's shown they outperform classical network layer solutions. 2. It's shown that ignoring the background safety beaconing messages in the study of vehicular information dissemination results in highly unrealistic results. > *** Weak Aspects: Comments to the author: What are the weak aspects of the paper? 1. Authors introduce too much previous works and some background information about safety information dissemination and facilities layer. The words of their original work are not enough compared with previous works and background information. They should describe their work specifically and clearly, especially facilities layer-based information dissemination and comparison with other mechanisms in section IV. 2. Authors do not describe the simulation difference between intelligence level 1 and level 2 in section V, so I doubt the results of performace evaluation. 3. In figure 2-4, It's not reasonable that information propagation delay decrease with the distance to the detected event. > *** Recommended Changes: Recommended changes. Please indicate any changes that should be made to the paper if accepted. 1. Authors should describe the previous works and background information briefly. They should describe their work specifically and clearly, especially facilities layer-based information dissemination and comparison with other mechanisms in section IV. 2. Authors should describe the simulation difference between intelligence level 1 and level 2 in section V. 3. Authors should given the reason for information propagation delay decrease with the distance to the detected event in figure 2-4. > *** Relevance and Timeliness: Rate the importance and timeliness of the topic addressed in the paper within its area of research. Little. (2) > *** 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. Marginal work and simple contribution. Some flaws. (2) > *** 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 clearness of text and figures, the completeness and accuracy of references. Readable, but revision is needed in some parts. (3)