  Source and channel coding over multiuser channels in which receivers have
access to correlated source side information is considered. For several
multiuser channel models necessary and sufficient conditions for optimal
separation of the source and channel codes are obtained. In particular, the
multiple access channel, the compound multiple access channel, the interference
channel and the two-way channel with correlated sources and correlated receiver
side information are considered, and the optimality of separation is shown to
hold for certain source and side information structures. Interestingly, the
optimal separate source and channel codes identified for these models are not
necessarily the optimal codes for the underlying source coding or the channel
coding problems. In other words, while separation of the source and channel
codes is optimal, the nature of these optimal codes is impacted by the joint
design criterion.
