1. A method comprising: assigning a first spatial division multiple access (SDMA) communication channel to a first user terminal, the first user terminal initially transmitting a first signal over the first SDMA communication channel; assigning a second SDMA communication channel to a second user terminal, the second user terminal initially transmitting a second signal over the second SDMA communication channel; and analyzing the first signal and the second signal to determine that the first user terminal is transmitting the first signal over the second SDMA communication channel and the second user terminal is transmitting the second signal over the first SDMA communication channel.