EECS 600 Advanced Computer Networks

[Date] Mar 21, 2005 Monday
[Note] Hongbo Jiang (hxj18@case.edu)

[Paper] S. Madden, M. J. Franklin, J. M. Hellerstein, and W. Hong. TAG: A Tiny AGgregation service for ad-hoc sensor networks. In Proc. of OSDI, 2002.

1. What is the metric in sensor networks?
In sensor networks, power is the primary metric, rather than traditional measures such as throughput or latency. 
Primary component of power consumption is communication.

2. Declarative queries are straightforward in sensor networks.
  
3. What is operator dependent benefit?

4. At each slot, collision problem can be omitted. Why?
Because each time slot is large enough, every signal can select its own micro-slot with one slot to avoid the collision.

5. Is slot fixed during propagation?
Yes, therefore it leads to another problem of synchronization.

6. How does the root know the max hop?
Maybe there exists initial step to collect some information. Another method is setting possible maximum hops within a network.

7. Channel Sharing. Why?
It is to reduce the power consumption. Because some suppress messages e.g., MAX would not suffer from channel sharing.

8. Guess operation. Why?
A good guess value can save energy greatly.