Multi-user detection in CDMA communications system

An iterative arrangement for receiving and detecting signals of a plurality of users in a CDMA communications system, comprising, for signals of each user:

• a signal combiner for subtracting regenerated signals of other users from a received signal to produce a modified received signal for the user;
• a receiver arrangement responsive to the modified received signal for producing a correlated signal for the user;
• a detector responsive to the correlated signal for producing a detected signal;
• and
• a signal regenerator responsive to the detected signal for producing a regenerated signal for the user for subtraction from the received signal in the signal combiners of other users;
• wherein the detector comprises a store, a limiting function, and a further signal combiner, the limiting function being responsive to an output of the further signal combiner to produce a limited signal having any of at least three possible values as the detected signal for the signal regenerator, the store being responsive to the output of the further signal combiner to store a representation of the detected signal in a current iteration, and the further signal combiner being arranged to combine a representation of the detected signal for a previous iteration from the store with a signal derived from the correlated signal supplied to the detector in the current iteration.