Broadcast Channels with Heterogeneous Arrival and Decoding Deadlines: Second-Order Achievability

TL;DR

This paper investigates broadcast channels with messages arriving at different times and deadlines, proposing a Marton coding-based scheme that improves performance over traditional time-sharing methods, especially for short packets.

Contribution

It introduces a novel coding scheme for broadcast channels with heterogeneous arrival and decoding deadlines, extending Marton's strategy to overlapping transmission windows.

Findings

Achieves improved rate regions over time-sharing methods.

Consistent with normal approximation in point-to-point settings.

Shows significant gains for short packet transmissions.

Abstract

A standard assumption in the design of ultra-reliable low-latency communication systems is that the duration between message arrivals is larger than the number of channel uses before the decoding deadline. Nevertheless, this assumption fails when messages arrive rapidly and reliability constraints require that the number of channel uses exceed the time between arrivals. In this paper, we consider a broadcast setting in which a transmitter wishes to send two different messages to two receivers over Gaussian channels. Messages have different arrival times and decoding deadlines such that their transmission windows overlap. For this setting, we propose a coding scheme that exploits Marton's coding strategy. We derive rigorous bounds on the achievable rate regions. Those bounds can be easily employed in point-to-point settings with one or multiple parallel channels. In the point-to-point setting with one or multiple parallel channels, the proposed achievability scheme is consistent with the normal approximation. In the broadcast setting, our scheme agrees with Marton's strategy for sufficiently large numbers of channel uses and shows significant performance improvements over standard approaches based on time sharing for transmission of short packets.