On the Capacity of Partially Cognitive Radios

TL;DR

This paper investigates the capacity limits of cognitive radios with partial message knowledge, deriving bounds and achievable regions for specific interference scenarios in both discrete and Gaussian channels.

Contribution

It provides the first outer bounds for partially cognitive interference channels and characterizes achievable regions in mixed interference Gaussian channels.

Findings

Outer bounds on capacity for weak interference cases.

Achievable regions for strong interference in Gaussian channels.

Partial capacity characterization for certain mixed interference scenarios.

Abstract

This paper considers the problem of cognitive radios with partial-message information. Here, an interference channel setting is considered where one transmitter (the "cognitive" one) knows the message of the other ("legitimate" user) partially. An outer bound on the capacity region of this channel is found for the "weak" interference case (where the interference from the cognitive transmitter to the legitimate receiver is weak). This outer bound is shown for both the discrete-memoryless and the Gaussian channel cases. An achievable region is subsequently determined for a mixed interference Gaussian cognitive radio channel, where the interference from the legitimate transmitter to the cognitive receiver is "strong". It is shown that, for a class of mixed Gaussian cognitive radio channels, portions of the outer bound are achievable thus resulting in a characterization of a part of this channel's capacity region.