2010/02/09 by Ehsan Ardestanizadeh, Michèle A. Wigger, Ardestanizadeh, Ehsan +6
Computer Science · Engineering · Mathematics · #Advanced MIMO Systems Optimization #Cooperative Communication and Network Coding #FOS: Computer and information sciences #Information Theory (cs.IT) #Wireless Communication Security Techniques #cs.IT #math.IT
paper · pdf · doi:10.48550/arxiv.1002.1781
Submitted to Transactions on Information Theory
openalex publication_date 2010/02/09 · arxiv created 2011/06/02 · arxiv updated 2011/06/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The capacity region of the N-sender Gaussian multiple access channel with feedback is not known in general. This paper studies the class of linear-feedback codes that includes (nonlinear) nonfeedback codes at one extreme and the linear-feedback codes by Schalkwijk and Kailath, Ozarow, and Kramer at the other extreme. The linear-feedback sum-capacity CL(N,P) under symmetric power constraints P is characterized, the maximum sum-rate achieved by linear-feedback codes when each sender has the equal block power constraint P. In particular, it is shown that Kramer's code achieves this linear-feedback sum-capacity. The proof involves the dependence balance condition introduced by Hekstra and Willems and extended by Kramer and Gastpar, and the analysis of the resulting nonconvex optimization problem via a Lagrange dual formulation. Finally, an observation is presented based on the properties of the conditional maximal correlation---an extension of the Hirschfeld--Gebelein--Renyi maximal correlation---which reinforces the conjecture that Kramer's code achieves not only the linear-feedback sum-capacity, but also the sum-capacity itself (the maximum sum-rate achieved by arbitrary feedback codes).