Patent ID: 6654365
Filing Date: 2003-11-25
Classification: H04B,H04L

Abstract:
A method of multiuser detection of signals transmitted via asynchronous CDMA by use of a filter having bit-matched outputs, comprising the steps of:developing a trellis representation of metrics based on a set of bit-matched filter outputs for communication in a channel being used concurrently by K users; obtaining an approximation to the maximum likelihood estimate of signals coded in a bit stream of a communication, said step of obtaining the estimate comprising a step of searching, by use of fractional-search algorithm, a fraction of possible paths of the trellis representation of a received sequence of data bits; wherein the algorithm is a breadth-first sparse trellis-search algorithm having a structure characterized by: there are 2Kâˆ’1 states partitioned into Y sublists; the X surviving trellis paths from the previous stage of a succession of trellis computations are extended to 2X paths; the 2X paths are assigned to the Y sublists according to state; and the best paths from each of the Y sublists are compared, and the best X paths are the survivors for a succeeding stage of the trellis search.