Summary: A new lower bound on the maximal error
probability for discrete memoryless multiple-access
Ali Nazari, Sandeep Pradhan and Achilleas Anastasopoulos
Electrical Engineering and Computer Science Dept.
University of Michigan, Ann Arbor, MI 48109-2122, USA
Abstract--In this work, a new lower bound for the maxi-
mal error probability of a two-user discrete memoryless (DM)
multiple-access channel (MAC) is derived. This is the first bound
of this type that explicitly imposes independence of the users'
input distributions (conditioned on the time-sharing auxiliary
variable) and thus results in a tighter sphere-packing exponent
when compared to the tightest known exponent derived by
An interesting problem in network information theory is
to determine the minimum probability of error which can
be achieved on a discrete memoryless (DM), multiple-access
channel (MAC). More specifically, a two-user DM-MAC is