======= Review 1 ======= *** Contributions: What are the major issues addressed in the paper? Do you consider them important? (Pls. comment explicitly on the relevance of the paper to MASS topics, the technical depth and the importance of the problem addressed.) [Be brief] The authors argue for the use of dynamic Carrier Sense as primary mechanism to perform congestion control in vehicular networks. The idea conceptually recalls the power control in CDMA. *** Strengths: What are the major reasons to accept the paper? [Be brief] The key aspect of this paper is the idea itself, proposing to use the receiver threshold as a mechanism to perform congestion control in vehicular networks. However i have some questions related to the implementation of the proposed systems *** Weaknesses: What are the most important reasons NOT to accept the paper? [Be brief] The paper proposes a cute idea, however impacts the physical layer of the IEEE802.11p and this means re-writing a standard that is something not really feasible. The tons of papers on TCP and similar have proven that any proposal that rewrites a standard and requires the market to change the components has an high chance to fail. *** Detailed comments: Please provide detailed comments that will be helpful to the TPC for assessing the paper, as well as feedback to the authors. The key aspect of this paper is the idea itself, proposing to use the receiver threshold as a mechanism to perform congestion control in vehicular networks. However i have some questions related to the implementation of the proposed systems The paper proposes a cute idea, however impacts the physical layer of the IEEE802.11p and this means re-writing a standard that is something not really feasible. The tons of papers on TCP and similar have proven that any proposal that rewrites a standard and requires the market to change the components has an high chance to fail. The idea is cute though and is certainly worth the chance of doubt although this reviewer thinks it is unlikely to be implemented anywhere in the real world. *** Familiarity: Rate your familiarity with the topic of the paper. Expert (3) *** Recommendation: Your overall rating. Borderline (top 30%) (3) ======= Review 2 ======= *** Contributions: What are the major issues addressed in the paper? Do you consider them important? (Pls. comment explicitly on the relevance of the paper to MASS topics, the technical depth and the importance of the problem addressed.) [Be brief] The paper deals with an enhancement of MAC protocol performance by adapting the carrier sense threshold in VANETs, focusing on the beacon reception rate which is essential for safety applications. By means of both analysis and simulations, they show that the optimal threshold depends on the vehicular density which is highly variable in VANETs; so, an adaptive mechanism is in order. The problem of improving MAC performance is very important for safety applications in VANETs, and it perfectly matches the conference topics. The technical depth of the paper is sufficient. *** Strengths: What are the major reasons to accept the paper? [Be brief] The paper deals with an important problem and it is well written. The analysis is correct and also the methodology followed in the simulations is good, even if some important details are not reported (see below). *** Weaknesses: What are the most important reasons NOT to accept the paper? [Be brief] Two important reasons: - the authors claim that "Carrier sense threshold has been totally ignored by the VANET research community". Although this is pretty true, is not totally true; for instance, see R.K.Schmidt, T. Leinmuller, G. Schafer, "Adapting the wireless carrier sensing for VANETs", in 6th International Workshop on Intelligent Transportation (WIT), Hamburg, Germany, March 2010. - the simulations seem to be performed correctly. Although in some figures confidence intervals are plotted, the number of runs is an important simulation parameter and must be reported. *** Detailed comments: Please provide detailed comments that will be helpful to the TPC for assessing the paper, as well as feedback to the authors. I don't have other comments, in addition to the issues reported above. Just two typos: - Fig. 5, at the end f the caption: "visibility" - same page, last paragraph of section VI: "every vehicle sends..." *** Familiarity: Rate your familiarity with the topic of the paper. Familiar (2) *** Recommendation: Your overall rating. Weak Accept (Top 20%) (4) ======= Review 3 ======= *** Contributions: What are the major issues addressed in the paper? Do you consider them important? (Pls. comment explicitly on the relevance of the paper to MASS topics, the technical depth and the importance of the problem addressed.) [Be brief] In this paper, the authors provide a general discussion about physical carrier sensing and its impact on the reception probability of beacons in VANETs. They also propose a mechanism to control the physical carrier sense in VANETS according to the vehicular density. The mechanism is proven to improve the reception ratio for vehicles in the safety range. The results are acquired by a simulation model. *** Strengths: What are the major reasons to accept the paper? [Be brief] *** Weaknesses: What are the most important reasons NOT to accept the paper? [Be brief] *** Detailed comments: Please provide detailed comments that will be helpful to the TPC for assessing the paper, as well as feedback to the authors. The reviewer appreciates the work done in this paper. The paper is well written and well organized. The problem and the solution are also well discussed. However, there are a few concerns related to the paper as follows: 1- The introduction part of the paper is long which is about three pages. A shorter problem statement, in which some general concepts are removed, is more appreciated for a conference paper. 2- The simulation model is not well described in the paper. How do the authors make sure that the model is correct? 3- There are a few grammatical and typing mistakes in the paper. 4- The contributions of the paper still have a lot of space for improvement. *** Familiarity: Rate your familiarity with the topic of the paper. Expert (3) *** Recommendation: Your overall rating. Weak Accept (Top 20%) (4)