Capacity of Coded Index Modulation

TL;DR

This paper introduces a concatenated coding scheme for index coding over Gaussian broadcast channels, leveraging side information at receivers to improve capacity and performance.

Contribution

It proposes a novel concatenated coding architecture that combines index coding with traditional coding to exploit receiver side information and derives its capacity region.

Findings

Capacity region characterized as a multiple-access channel.

Demonstrated improved performance through simulations.

Relates side information gain to code efficiency.

Abstract

We consider the special case of index coding over the Gaussian broadcast channel where each receiver has prior knowledge of a subset of messages at the transmitter and demands all the messages from the source. We propose a concatenated coding scheme for this problem, using an index code for the Gaussian channel as an inner code/modulation to exploit side information at the receivers, and an outer code to attain coding gain against the channel noise. We derive the capacity region of this scheme by viewing the resulting channel as a multiple-access channel with many receivers, and relate it to the 'side information gain' -- which is a measure of the advantage of a code in utilizing receiver side information -- of the inner index code/modulation. We demonstrate the utility of the proposed architecture by simulating the performance of an index code/modulation concatenated with an off-the-shelf convolutional code through bit-interleaved coded-modulation.