  We consider a two user fading Multiple Access Channel with a wire-tapper
(MAC-WT) where the transmitter has the channel state information (CSI) to the
intended receiver but not to the eavesdropper (eve). We provide an achievable
secrecy sum-rate with optimal power control. We next provide a secrecy sum-rate
with optimal power control and cooperative jamming (CJ). We then study an
achievable secrecy sum rate by employing an ON/OFF power control scheme which
is more easily computable. We also employ CJ over this power control scheme.
Results show that CJ boosts the secrecy sum-rate significantly even if we do
not know the CSI of the eve's channel. At high SNR, the secrecy sum-rate (with
CJ) without CSI of the eve exceeds the secrecy sum-rate (without CJ) with full
CSI of the eve.
