Delay diversity and spatial rotation systems and methods

A method of communicating in a wireless network, comprising:

• receiving a number (Nss) of input signals;
• transforming at least a portion of the Nss input signals using an Inverse Fast Fourier Transform (IFFT);
• producing a number (Ntx) of output signals that are respectively time shifted copies of the Nss input signals, wherein Ntx is greater than or equal to Nss;
• operating on the Ntx output signals using a Ntx-by-Ntx unitary spatial rotation matrix to provide respective spatial rotation to all of the Ntx output signals, wherein the Ntx-by-Ntx unitary spatial rotation matrix comprises a Walsh matrix, wherein the transforming of the at least a portion of the Nss input signals is performed before the producing of the number of Ntx output signals that are respectively time shifted copies of the Nss input signals and before the operating on the Ntx output signals using the Ntx-by-Ntx unitary spatial rotation vector matrix;
• and
• broadcasting the Ntx output signals, which are respectively time shifted and respectively spatially rotated, to reduce nulls, including deep nulls, associated with the Nss input signals, in a received channel that is one of a certain number of highly correlated channels.

A wireless transmitter for transmitting a plurality of transmit stream signals, the transmitter comprising:

• an Inverse Fast Fourier Transform (IFFT) module that transforms one or more of a plurality of spatial stream signals using an Inverse Fast Fourier Transform (IFFT);
• a time shift module adapted to introduce time shifts to the one or more of the plurality of spatial stream signals to produce a plurality of time-shifted spatial stream signals, wherein the spatial stream signals are generated based at least in part on a data stream;
• and
• a spatial rotation module communicatively coupled with the time shift module and adapted to receive the plurality of time-shifted spatial stream signals from the time shift module and to operate on each of the time-shifted spatial stream signals with a spatial rotation vector matrix to apply respective spatial rotation to each of the plurality of time-shifted spatial stream signals, to thereby map each of the plurality of time-shifted spatial stream signals correspondingly to a respective one of the transmit stream signals that are respective time-shifted spatially-rotated spatial stream signals of a plurality of time-shifted spatially-rotated spatial stream signals, to reduce nulls, including deep nulls, associated with the data stream, in a received channel that is one of a certain number of highly correlated channels, wherein the spatial rotation vector matrix comprises a Walsh matrix, wherein the transformation of the one or more of the plurality of spatial stream signals using the Inverse Fast Fourier Transform (IFFT) is performed prior to the introduction of time shifts to the one or more of the plurality of spatial stream signals and prior to the operation on each of the time-shifted spatial stream signals with the spatial rotation vector matrix.

A non-transitory computer-readable medium having stored thereon computer-executable instructions executed by a processor to perform the acts comprising:

• introducing respective time shifts to each of a plurality of spatial stream signals to produce a plurality of time-shifted spatial stream signals, wherein each of the plurality of spatial stream signals is based at least in part on a data stream;
• operating on each of the plurality of time-shifted spatial stream signals with a spatial rotation vector matrix to apply respective spatial rotation to each of the plurality of time-shifted spatial stream signals, to thereby map the plurality of time-shifted spatial stream signals respectively to transmit signals that are respective time-shifted spatially- rotated spatial stream signals of a plurality of time-shifted spatially-rotated spatial stream signals, to reduce nulls, including deep nulls, associated with the data stream, in a received channel, wherein the spatial rotation vector matrix is a Walsh matrix;
• and
• transforming each of a plurality of spatial stream signals using an Inverse Fast Fourier Transform (IFFT), wherein the transforming of each of a plurality of spatial stream signals using an Inverse Fast Fourier Transform (IFFT) is applied to the plurality of spatial stream signals before the introducing of respective time shifts is applied to each of the plurality of spatial stream signals and before the operating on each of the plurality of time-shifted spatial stream signals with a spatial rotation vector matrix.