The present invention can improve efficiency in wireless radio networks using spatial division multiple access (SDMA) strategies. One embodiment of the invention includes determining a quality parameter of a user terminal based on a signal received from the user terminal at a base station. One embodiment further includes determining a co-spatial constraint on the user terminal based on the quality parameter, the co-spatial constraint comprising a limitation on the quantity of additional user terminals with which the user terminal can share a conventional communications channel.