Overloaded array processing with spatially reduced search jointdetection

摘要

An antenna array is overloaded when the number of cochannelnsignals in its operating environment exceeds the number of elements.nThis paper proposes an iterative joint detection technique, spatiallynreduced search joint detection (SRSJD), that well approximates the jointnmaximum likelihood (JML) receiver, while reducing its computationalncomplexity by several orders of magnitude. This complexity reduction isnachieved by first exploiting the spatial separation between interferingnsignals with a linear preprocessing stage, and second, performingniterative joint detection with a reduced-state trellis formed over spaceninstead of time. These novel joint detection trellises are possiblyntail-biting and vary in structure from stage to stage. Throughnsimulation, SRSJD is shown to demodulate over 2M synchronous quaternarynphase-shift keying signals of zero excess bandwidth with an M elementncircular array. The channels of all users are assumed known