Abstract: An adaptive procedure that optimizes the parameters of a receiver filter such as a Multiuser Detection (MUD) applied to Direct-Sequence Code Division Multiple Access (DS-CDMA) is disclosed. This procedure takes into account the constraints imposed by the absence of training data sequences sent by the transmitter and required to adapt the filter parameters at the receiver. The adaptation consists in using two distinct data sequences transmitted through the same channel; one data sequence is transmitted as payload data and a second data sequence is transmitted as training data used to adapt the filter parameters at the receiver. Parameters of the receiver filter are adapted in presence of varying channels at the same time as the data information sequences are transmitted. The adaptation is realized following a mixed adaptation procedure based on a direct (without channel identification) and indirect (with channel identification) scheme.

Abstract: A description of an adaptable multiuser processing unit applied to Direct-sequence Code Division Multiple Access (DS-CDMA) is disclosed. The adaptable multiuser processing unit consists of cascade filters where each filter is adapted independently. The adaptation of a first filter is based on the error between the output of the first filter and a desired signal, in the same way for the other filters. The adaptation is realized follow a direct, without channel identification, or indirect, with channel identification, procedure. The first filter receives the input signal in Baud (1/T) or Fractionally (k/T) spaced and the last filter gives to the MUD output the decisions on the symbols estimated for each users. A decision feedback may be applied to the input of each filter such as the conventional Decision Feedback Equalizer (DFE). In more, each filter can be linear or nonlinear.