# A Novel Transmission Scheme for the $K$-user Broadcast Channel with Delayed CSIT

## TL;DR

This paper introduces a new, simple transmission scheme for the $K$-user broadcast channel with delayed CSIT, achieving capacity in symmetric erasure channels and outperforming existing methods at finite SNR.

## Contribution

It proposes a novel, easy-to-evaluate transmission scheme that achieves the capacity region for symmetric erasure BCs and improves finite SNR performance for fading Gaussian BCs.

## Key findings

- Achieves the capacity region of symmetric erasure BCs.
- Attains optimal degrees of freedom at high SNR.
- Outperforms existing schemes in finite SNR regimes.

## Abstract

The state-dependent $K$-user memoryless Broadcast Channel~(BC) with state feedback is investigated. We propose a novel transmission scheme and derive its corresponding achievable rate region, which, compared to some general schemes that deal with feedback, has the advantage of being relatively simple and thus is easy to evaluate. In particular, it is shown that the capacity region of the symmetric erasure BC with an arbitrary input alphabet size is achievable with the proposed scheme. For the fading Gaussian BC, we derive a symmetric achievable rate as a function of the signal-to-noise ratio~(SNR) and a small set of parameters. Besides achieving the optimal degrees of freedom at high SNR, the proposed scheme is shown, through numerical results, to outperform existing schemes from the literature in the finite SNR regime.

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Source: https://tomesphere.com/paper/1705.05255