An Achievable Rate Region for a Multiuser Half-Duplex Two-Way Channel

Feedback is known to enlarge the capacity region of a multiuser channel. However, none of the information theoretic analysis account for resource usage of the feedback link. In this paper, we adopt a novel two-way formulation for multiuser systems, which jointly designs the uplink and downlink communication. By assuming that nodes are half-duplex (in time) and feedback shares resources with data, all resource usage is accurately accounted in the system. Our achievable rate region shows that feedback is beneficial only if the the channel is two- way, i.e, there is data to be sent in both directions.