Patent ID: 8902869

Claim:
A method, in a communication system, of generating and causing to be transmitted data units conforming to a first physical layer (PHY) mode and data units conforming to a second PHY mode different than the first PHY mode, wherein the communication system utilizes a plurality of channels for transmitting data units conforming to the first PHY mode, and wherein each channel of the plurality of channels has a first bandwidth, the method comprising: generating a first data unit conforming to the first PHY mode, wherein generating the first data unit includes generating a first series of orthogonal frequency division multiplexing (OFDM) symbols; causing the first data unit to be transmitted via a channel of the plurality of channels; generating a second data unit conforming to the second PHY mode, wherein generating the second data unit includes generating a second series of OFDM symbols, and at least a portion of the second series of OFDM symbols includes one of (i) more upper-edge guard tones than lower-edge guard tones, or (ii) more lower-edge guard tones than upper-edge guard tones: determining a frequency band for transmitting the second data unit, wherein the frequency band has a second bandwidth equal to the first bandwidth divided by an integer n, wherein n≧2, determining the frequency band for transmitting the second data unit includes excluding one of (i) a lowest sub-band of each of one or more channels in the plurality of channels when the portion of the second series of OFDM symbols includes more upper-edge guard tones than lower-edge guard tones or (ii) a highest sub-band of each of the one or more channels in the plurality of channels when the portion of the second series of OFDM symbols includes more lower-edge guard tones than upper-edge guard tones, and each sub-band of each channel in the plurality of channels has the second bandwidth; and causing the second data unit to be transmitted via the determined frequency band.