Bounds and Capacity Theorems for Cognitive Interference Channels with State

TL;DR

This paper investigates the capacity limits of cognitive interference channels with state information, deriving bounds and exact regions for various channel models, including discrete memoryless and Gaussian cases, under different state knowledge scenarios.

Contribution

It provides new inner and outer bounds on capacity regions for cognitive interference channels with state, and characterizes the capacity for several specific channel conditions.

Findings

Capacity region bounds are derived for discrete memoryless channels.

Exact capacity regions are characterized for degraded semideterministic and less noisy channels.

Full capacity regions are obtained for channels with certain conditions and for cases where state is known at both transmitter and receiver.

Abstract

A class of cognitive interference channel with state is investigated, in which two transmitters (transmitters 1 and 2) communicate with two receivers (receivers 1 and 2) over an interference channel. The two transmitters jointly transmit a common message to the two receivers, and transmitter 2 also sends a separate message to receiver 2. The channel is corrupted by an independent and identically distributed (i.i.d.) state sequence. The scenario in which the state sequence is noncausally known only at transmitter 2 is first studied. For the discrete memoryless channel and its degraded version, inner and outer bounds on the capacity region are obtained. The capacity region is characterized for the degraded semideterministic channel and channels that satisfy a less noisy condition. The Gaussian channels are further studied, which are partitioned into two cases based on how the interference compares with the signal at receiver 1. For each case, inner and outer bounds on the capacity region are derived, and partial boundary of the capacity region is characterized. The full capacity region is characterized for channels that satisfy certain conditions. The second scenario in which the state sequence is noncausally known at both transmitter 2 and receiver 2 is further studied. The capacity region is obtained for both the discrete memoryless and Gaussian channels. It is also shown that this capacity is achieved by certain Gaussian channels with state noncausally known only at transmitter 2.