Techniques for making channel assignments to reduce interference and increase capacity of wireless networks are described. In an implementation, a first station receives a signal from a second station. The first station measures a signal strength of the received signal, and determines that the signal strength is relatively weak compared to other signals received at the first station from other stations. A set of OFDMA subcarriers available for assignment is divided into a first subset for relatively weak signals within a first cell and a second subset for relatively strong signals within the first cell. The second station is assigned a transmit subchannel that is formed for a predetermined period of time by the first subset of subcarriers, the transmit subchannel assigned based on the determination that the signal strength of the received signal is relatively weak.