  In a multi-access channel, completion time refers to the number of channel
uses required for users, each with some given fixed bit pool, to complete the
transmission of all their data bits. In this paper, the characterization of the
completion time region is based on the concept of constrained rates, where
users' rates are defined over possibly different number of channel uses. An
information theoretic formulation of completion time is given and the
completion time region is then established for two-user Gaussian multi-access
channel, which, analogous to capacity region, characterizes all possible
trade-offs between users' completion times.
