{
  "abstract": "We completely characterize the second-order coding rate region of the two-user Gaussian multiple-access channel at points in the relative interior of the sum-rate face, under maximal per-codeword power constraints. For any fixed average error probability $0 < \\varepsilon < 1/2$, a nontrivial mixture of power splits reduces the sum-rate dispersion and strictly improves upon standard inner bounds based on a constant power split. Thus, a constant power split, although sufficient to attain the first-order capacity region, is insufficient for second-order optimality in this regime. Our achievability proof builds on the constant composition and coded time-sharing framework of Scarlett, Martinez, and Guillén i Fàbregas, with an optimization over admissible power splits. A matching second-order converse establishes the optimality of the resulting coded time-sharing strategy.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.18013",
  "author_total": 1,
  "authors": [
    {
      "name": "Vincent Y. F. Tan"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/6n8pcbhkjmy9f.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.18013",
  "fulltext_url": null,
  "id": "6n8pcbhkjmy9f",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.18013",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cs.IT"
    ],
    [
      "arxiv",
      "math.IT"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.18013",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-16",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/6n8pcbhkjmy9f.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:04Z",
      "native_id": "2609.18013",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.18013"
    }
  ],
  "subjects": [
    {
      "field": "mathematics",
      "origin": "arxiv:math.IT",
      "subfield": "general"
    }
  ],
  "title": "Second-Order Asymptotics for the Gaussian MAC on the Relative Interior of the Sum-Rate Face",
  "title_text": "Second-Order Asymptotics for the Gaussian MAC on the Relative Interior of the Sum-Rate Face",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:04Z",
  "url": "https://research.draconitic.com/paper/6n8pcbhkjmy9f",
  "venue": "arXiv",
  "versions": []
}