  This paper considers a class of multi-channel random access algorithms, where
contending devices may send multiple copies (replicas) of their messages to the
central base station. We first develop a hypothetical algorithm that delivers a
lower estimate for the access delay performance within this class. Further, we
propose a feasible access control algorithm achieving low access delay by
sending multiple message replicas, which approaches the performance of the
hypothetical algorithm. The resulting performance is readily approximated by a
simple lower bound, which is derived for a large number of channels.
