  Information freshness has attracted increasingly attention in the past decade
as it plays a critical role in the emerging real-time applications. Age of
information (AoI) holds the promise of effectively characterizing the
information freshness, hence widely considered as a fundamental performance
metric. However, in multiple-device scenarios, most existing works focus on the
analysis and optimization of AoI based on queueing systems. The study for a
unified approach for general multiple access control scheme in
freshness-oriented scenarios remains open. In this paper, we take into
consideration the combination of the fundamental freshness metric AoI and
multiple access control schemes to achieve efficient cross-layer analysis and
optimization in freshness-oriented scenarios, which is referred to as fresh
multiple access. To this end, we build a unified framework with a discrete-time
tandem queue model for fresh multiple access. The unified framework enables the
analysis and optimization for general multiple access protocols in fresh
multiple access. To handle the high dimension framework embedded in fresh
multiple access, we introduce large model approaches for the Markov chain
formulation in AoI oriented scenarios. Two typical AoI-based metric are studied
including age of incorrect information (AoII) and peak AoII. Moreover, to
address the computational complexity of the large model, we present mean-field
approximations which significantly reduces the dimension of the Markov chain
model by approximating the integral affect of massive devices in fresh multiple
access.
