A method for simultaneous transmission in time and frequency of multiple communications of data using orthogonal frequency division multiplexing (OFDM) modulation includes transmitting the multiple communications of data at a same time on a single channel. A first starting signal, transmitted using a first network device, and a second starting signal, transmitted using a second network device, are used in transmission of a frame. Properties of the first starting signal and the second starting signal for transmission of each of the multiple communications are modified by shifting a frequency of the first starting signal with respect to a frequency of the second starting signal so that remaining communications coincident in time and frequency with respect to a given communication are ignored. The frequency of the first starting signal is shifted an amount equal to a fraction of a separation between carriers of the OFDM modulation.