Two-Way Networks: When Adaptation Is Useless
Most wireless communication networks are two-way, where nodes act as both sources and destinations of messages. This allows for "Adaptation" at or "Interaction" between the nodes - a node's channel inputs may be functions of its message(s) and previously received signals, in contrast to feedback-free one-way channels where inputs are functions of messages only. How to best adapt, or cooperate, is key to two-way communication, rendering it complex and challenging. However, examples exist of channels where adaptation is not beneficial from a capacity perspective; it is known that for the point-to-point two-way modulo 2 adder and Gaussian channels, adaptation does not increase capacity. The authors ask whether analogous results hold for several multi-user two-way networks.