  The two-user Multiple Access Channel (MAC) with cooperative encoders and
Channel State Information (CSI) is considered where two different scenarios are
investigated: A two-user MAC with common message (MACCM) and a two-user MAC
with conferencing encoders (MACCE). For both situations, the two cases where
the CSI is known to the encoders either non-causally or causally are studied.
Achievable rate regions are established for both discrete memoryless channels
and Gaussian channels with additive interference. The achievable rate regions
derived for the Gaussian models with additive interference known non-causally
to the encoders are shown to coincide with the capacity region of the same
channel with no interference. Therefore, the capacity region for such channels
is established.
