On the Degrees of Freedom of $K$-User SISO Interference and X Channels with Delayed CSIT

TL;DR

This paper introduces new multi-phase transmission schemes for $K$-user SISO interference and X channels with delayed CSIT, achieving higher degrees of freedom than previously known, through innovative interference management techniques.

Contribution

The paper proposes novel multi-phase transmission schemes with partial interference nulling and distributed interference management for channels with delayed CSIT, improving DoF performance.

Findings

Achieved higher DoF than previous methods for both channels.

Developed multi-phase schemes with interference nulling and user scheduling.

Demonstrated the effectiveness of distributed higher-order symbol generation.

Abstract

The $K$-user single-input single-output (SISO) AWGN interference channel and $2\times K$ SISO AWGN X channel are considered where the transmitters have the delayed channel state information (CSI) through noiseless feedback links. Multi-phase transmission schemes are proposed for both channels which possess novel ingredients, namely, multi-phase partial interference nulling, distributed interference management via user scheduling, and distributed higher-order symbol generation. The achieved degrees of freedom (DoF) values are greater than the best previously known DoFs for both channels with delayed CSI at transmitters.