Low Cost Arduino based Wireless Mesh Network - Noise and interference immune

Hi everyone!

I want to create a wireless mesh network. And I also have to do some controlling tasks on each node, so there will be an Arduino at each node. Now this mesh has to deliver plain data from one point to another. The nodes need to have an identity, and their positions relative to each other may change with time in the practical environment. And I need to implement the most economical method to achieve this. Noise and interference can be issues in this project.

Please suggest which module would be the best suited for this. I searched some low cost RF modules on sparkfun, but they had no built-in physical identity and they were said to get noise and interference as well.

Sounds like a school project. What have you done so far?