Method and apparatus using sounding PPDUs to provide range extension to IEEE 802.11n signals

A non-transitory computer-readable medium encoded with instructions which, when executed by a processor, performs a method including:

• dividing a digital signal into a plurality of spatial streams;
• mapping the spatial streams into a plurality of space-time streams that each include data and a preamble for estimating a channel transfer function;
• spatially mapping the space time streams by applying a spatial expansion matrix to data and to first training symbols used in the preamble to probe a channel experienced by the data and by applying an extension matrix to second training symbols used in the preamble to probe at least one additional dimension of the channel to enable use of beamforming to achieve range extension, wherein the spatial expansion matrix and the extension matrix form an overall matrix that has at least two orthogonal columns with different norms;
• and
• wirelessly transmitting each of the spatially mapped space-time streams.

A non-transitory computer-readable medium encoded with instructions which, when executed by a processor, performs a method including:

• receiving a wireless signal that includes a preamble used to estimate a channel transfer function H of a channel experienced by the wireless signal during transmission thereof, wherein the preamble includes first training symbols to which a spatial expansion matrix QD is applied and second training symbols to which an extension matrix QE is applied, wherein the first training symbols probe the channel experienced by the wireless signal and the second training symbols probe at least one additional dimension of the channel and wherein the spatial expansion matrix QD and the extension matrix QE form an overall matrix that has at least two orthogonal columns with different norms;
• estimating values for HQE and HQD using known values for QD and QE;
• and
• obtaining a value for the channel transfer function H from the estimated values of HQE and HQD.