On the Power of Cooperation: Can a Little Help a Lot? (Extended Version)

In this paper, we propose a new cooperation model for discrete memoryless multiple access channels (DM-MACs). While in prior cooperation models (e.g., DM-MAC with conferencing encoders) the increase in a network’s sum-capacity that results from cooperation is no more than the rate introduced by the cooperation mechanism, we show that in our model for a particular sequence of channels, the increase in sum-capacity is significantly larger than the cooperation rate. This result contrasts with the network coding literature for networks of point to point links, where attempts to find examples in which similar small network modifications yield large capacity benefits have to date been unsuccessful.