On the Multiple Access Channel with Asynchronous Cognition

TL;DR

This paper introduces and analyzes the capacity regions of asynchronous cognitive multiple access channels with two transmitters, considering message and codeword side-information, providing bounds and specializations for Gaussian cases.

Contribution

It presents new models for asynchronous cognitive MACs, derives capacity bounds, and distinguishes between message and codeword side-information effects.

Findings

Inner and outer bounds on capacity regions established

Specialized results for Gaussian channels provided

Illustrative example differentiates message and codeword side-information

Abstract

In this paper we introduce the two-user asynchronous cognitive multiple access channel (ACMAC). This channel model includes two transmitters, an uninformed one, and an informed one which knows prior to the beginning of a transmission the message which the uninformed transmitter is about to send. We assume that the channel from the uninformed transmitter to the receiver suffers a fixed but unknown delay. We further introduce a modified model, referred to as the asynchronous codeword cognitive multiple access channel (ACC-MAC), which differs from the ACMAC in that the informed user knows the signal that is to be transmitted by the other user, rather than the message that it is about to transmit. We state inner and outer bounds on the ACMAC and the ACC-MAC capacity regions, and we specialize the results to the Gaussian case. Further, we characterize the capacity regions of these channels in terms of multi-letter expressions. Finally, we provide an example which instantiates the difference between message side-information and codeword side-information.