Multiuser channel estimation for detection of cochannel signals

Estimation of the channel impulse responses of multiple cochannel users is a key requirement of all multiuser detection and interference cancellation techniques, though little attention has been paid to subject in the context of TDMA systems. This paper addresses a pilot-based technique for multiuser channel estimation in a TDMA system, and makes several new contributions: it allows for time variation of the channels within and between training sequences, it accounts for colouration of the sampled noise sequence as well as correlation between the channel taps, and it considers users to be asynchronous resulting in a technique whereby explicit timing recovery is unnecessary. In addition, it addresses selection of appropriate training sequences.