Joint Map Detection and Channel Estimation for Cdma over Frequency-selective Fading Channels

This paper presents a centralized multiuser maximum a posteriori (MAP) detector for code division multiple access (CDMA) signals on frequency-selective fast-fading channels. Importantly, the algorithm does not assume perfect channel state information at the receiver. The key idea is to expand the hypothesis trellis for the purpose of joint channel estimation and equalization for all users. Using the additional hypotheses, minimum mean square error (MMSE) channel estimation techniques are coupled with the MAP algorithm. This algorithm is applicable to synchronous systems, as well as asyn-chronous systems provided that the user timing oosets are known.