The Broadcast Approach in Communication Networks

TL;DR

This paper reviews the broadcast approach for communication over channels with unknown, time-varying states, highlighting strategies that balance short-term guarantees and long-term performance in different operational scenarios.

Contribution

It provides a comprehensive overview of applying the broadcast approach to various channels and networks, addressing both frequent and infrequent state variations.

Findings

Effective long-term strategies for ergodic channels

Design principles for short-term performance guarantees

Application guidelines for different network models

Abstract

This paper reviews the theoretical and practical principles of the broadcast approach to communication over state-dependent channels and networks in which the transmitters have access to only the probabilistic description of the time-varying states while remaining oblivious to their instantaneous realizations. When the temporal variations are frequent enough, an effective long-term strategy is adapting the transmission strategies to the system's ergodic behavior. However, when the variations are infrequent, their temporal average can deviate significantly from the channel's ergodic mode, rendering a lack of instantaneous performance guarantees. To circumvent a lack of short-term guarantees, the {\em broadcast approach} provides principles for designing transmission schemes that benefit from both short- and long-term performance guarantees. This paper provides an overview of how to apply the broadcast approach to various channels and network models under various operational constraints.