We present multiuser space-time receiver algorithms for synchronization, channel estimation, and data detection in the downlink of a universal mobile telecommunications system (UMTS)/time-division duplex (TDD) cellular communication system with multiple receive antennas. These algorithms were designed for use in a network monitoring device that analyzes the interference situation present, thereby allowing the operators to improve their networks. For interference analysis, we decode the broadcast channels (BCHs) of surrounding base stations. To cope with the widely differing power levels of signals received from different base stations, we combine multiuser space-time signal processing techniques with reestimation and successive cancellation schemes. Simulation results demonstrate that our algorithms enable reliable BCH data detection even at low SINR.