Asymmetric cooperative multiple access channels with delayed CSI

We consider a two-user multiaccess channel with degraded messages sets in which the channel state information (CSI) is revealed, strictly causally or with one-unit delay, to only the encoder that sends the common message. We study the capacity region of this model. We establish inner and outer bounds on the capacity region. We also identify some special cases in which the bounds meet, thereby characterizing the capacity region in these cases. The outer bound is non-trivial and has a relatively simple convenient expression (it incorporates only one auxiliary random variable). The coding scheme that we use for the inner bound utilizes rate-splitting to resolve a tension at the informed encoder among exploiting the knowledge of the (delayed) CSI (through a noisy network coding or quantize-map-and-forward state compression) and sending information cooperatively with the other encoder. Together with some previous results on closely related models, the results in this paper shed more light on the utility of delayed CSI for increasing the capacity region of multiaccess channels; and tie with some recent progress in this framework.