On the Capacity of the Multiuser Vector Adder Channel

TL;DR

This paper analyzes the capacity limits of a multiuser vector adder channel with multiple frequencies and users, deriving bounds for both coordinated and uncoordinated transmission scenarios as the system scales.

Contribution

It provides asymptotic upper and lower bounds on the channel capacity, highlighting differences between coordinated and uncoordinated transmission strategies.

Findings

Lower bound increases with system load in coordinated case

Uncoordinated case capacity remains bounded by a constant

Asymptotic bounds depend on the ratio of users to frequencies

Abstract

We investigate the capacity of the $Q$-frequency $S$-user vector adder channel (channel with intensity information) introduced by Chang and Wolf. Both coordinated and uncoordinated types of transmission are considered. Asymptotic (under the conditions $Q \to \infty$, $S = \gamma Q$ and $0 < \gamma < \infty$) upper and lower bounds on the relative (per subchannel) capacity are derived. The lower bound for the coordinated case is shown to increase when $\gamma$ grows. At the same time the relative capacity for the uncoordinated case is upper bounded by a constant.