Patent ID: 8422571

Claim:
A method for simultaneous transmission in time and frequency of multiple communications of data using orthogonal frequency division multiplexing (OFDM) modulation, the method comprising: transmitting the multiple communications of data at a same time on a single channel, wherein a first starting signal and a second starting signal are used in transmission of a frame; modifying properties of the first starting signal and the second starting signal for transmission of each of the multiple communications 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, wherein the frequency of the first starting signal is shifted an amount equal to a fraction of a separation between carriers of the OFDM modulation; using a first network device, transmitting the first starting signal using the single channel; using a second network device, transmitting the second starting signal using the single channel; at a third network device, receiving the first starting signal and the second starting signal using the single channel; selectively allowing communication with the first network device based on the frequency of the first starting signal; and ignoring communication from the second network device based on the frequency of the second starting signal.