The unbounded benefit of encoder cooperation for the k-user MAC

Cooperation strategies that allow communication devices to work together can improve network capacity. This paper generalizes the “cooperation facilitator” (CF) model from the 2-user to the k-user multiple access channel (MAC), extending capacity bounds, characterizing all k-user MACs for which the sum-capacity gain of encoder cooperation exceeds the capacity cost that enables it, and demonstrating an infinite benefit-cost ratio in the limit of small cost.