| abstract |
In a code-division-multiple-access (CDMA) system employing spread-spectrum modulation, mobile stations (15) initially seek access to a selected one of two or more groups of common packet channels (CPCHs) serviced through a base station (13). A second order collision resolution phase, conducted between the base stations (13) and contending mobile stations (15), serves to allocate one or more available channels from the selected group of channels among the contending mobile stations. In the collision resolution phase, each mobile station (15) randomly selects a collision detection (CD) signature and sends that signature in a CD preamble. For each available channel in the group, the base station (13) assigns one of the mobile stations (15). For each assigned mobile station, the base station (13) transmits a CD acknowledgement that corresponds to the CD preamble of the assigned mobile station (15) and identifies the available channel assigned to that mobile station (15). |