======= Review 1 ======= *** Familiarity: Rate your familiarity with the topic of the paper. Familiar (2) *** Recommendation: Your overall rating. Borderline (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] The paper studied the delay-power consumption trade-off MANET systems with cooperation and asymmetric power allocation. The paper first identified that power is a critical resource in WSN. By applying probability modeling, the authors made an argument that cooperation and asymmetric power allocation can achieve better delay-power trade off. *** Strengths: What are the major reasons to accept the paper? [Be brief] The authors proposed a new idea, and completed the argument for the idea. *** Weaknesses: What are the most important reasons NOT to accept the paper? [Be brief] Please refer to the "detailed comments" section. *** Detailed comments: Please provide detailed comments that will be helpful to the TPC for assessing the paper, as well as feedback to the authors. This paper has the following weaknesses: 1. Too many grammatical errors. e.g. second to last line of the abstract, shows --> show; second to last line of section 1, is --> are; first line of second paragraph of right column on page 2, requires --> require; first paragraph of right column on page 4, should be "terminated, transition"; left column on page 8, should be "1/p", instead of "1.p"; and many others. 2. The authors should explain more on the equations. 3. The authors could provide more detail about simulations, e.g simulation settings and parameters. 4. In this paper, the authors made the argument based on some assumptions and constraints of extreme conditions. The authors could provide more information on how useful the idea is in some more general scenarios. ======= Review 2 ======= *** Familiarity: Rate your familiarity with the topic of the paper. Expert (3) *** Recommendation: Your overall rating. Weak Accept (4) *** 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] This paper presents an analytical model, in addition to simulation experiments, of the delay-energy trade-off in cooperative forwarding of data in wireless sensor networks. For the purpose of analysis it considers a model where all nodes can directly communicate with each other. Cooperation, in this context, means that other nodes can act as relays to deliver the packet from a source to a destination. The paper considers both symmetric and asymmetric wake-up schedules, and traffic dependent as well as traffic independent schemes. The work is interesting and definitely of relevance to MASS. The analysis appears to be correct. *** Strengths: What are the major reasons to accept the paper? [Be brief] This is interesting approach to a problem. The results support intuition. The most interesting conclusion, in my opinion, is that with asymmetric wake-up schedule it is possible to achieve delays as short as those with the flooding-based approach, yet the energy-consumption of the asymmetric wake-up approach is significantly lower than that of flooding. *** Weaknesses: What are the most important reasons NOT to accept the paper? [Be brief] In a way, the strength and weakness of this paper are two sides of the same coin and concern the asymmetric wake-up approach. As the number of nodes increases, the probability of the beacon node being awake in the asymmetric approach increases, reaching 1 in the limiting case. The source node relays its packet to the beacon node, and then the beacon node sends the packet to the destination. Conceptually, the model reduces to an Access Point + wireless station model similar to the IEEE 802.11 system. Viewed this way, the improvement of the ASYM approach does not appear to be a novel idea. Moreover, the paper does not mention a realistic sensing application where arbitrary pairs of nodes would need to communicate with each other as opposed to sending their data to a common sink. *** Detailed comments: Please provide detailed comments that will be helpful to the TPC for assessing the paper, as well as feedback to the authors. This paper would benefit from a stronger justification of various assumptions. Some examples are: 1. In Section 3 it is assumed that time is slotted. This seems to contradict earlier criticism of some protocols for requiring time synchronization. Wouldn't a slotted approach also require strict time synchronization? 2. Collision of messages is not considered at all. The justification that collisions are unlikely due to low traffic does not hold when flooding is employed. Also, what if there is more than one source concurrently trying to send packets to destinations? 3. Instead of considering power consumption of individual nodes, the average power consumption or total power consumption is considered on the grounds that for applications like industrial monitoring all sensor nodes would be connected to the power supply. I would like to suggest that for such applications, the energy consumed by the sensor network (as a fraction of the total energy consumption of the factory) would be so small that energy savings of the sensor network would not be an important consideration. ======= Review 3 ======= *** Familiarity: Rate your familiarity with the topic of the paper. Familiar (2) *** Recommendation: Your overall rating. Weak Accept (4) *** 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 effect of cooperation and asymmetric power allocation in power saving MAC protocols is investigated in this paper. It is shown that the transmission delay can be reduced by a constant factor through cooperating with symmetric power allocation. The delay can be further reduced if an asymmetric power allocation is used. This is the first paper to study the delay-power consumption trade-off with cooperation and asymmetric power allocation in wireless sensor networks. *** 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 presentation of the paper is rough, and there exists some grammar errors. This paper provides plenty of theoretical analysis. However, no novel or creative method is addressed. The contribution of this paper is not strong. There are a lot of effective routing protocols in wireless sensor networks. Authors should consider compare with other protocols too, not only the flooding protocol which is rarely used in real applications. Some grammar errors: a overheard our results also shows the wireless senor networks (WSN) has been collisions is one of these them in other case, it staying in a ... a factor of the of p