Precoder structure for MIMO precoding

A wireless communication transceiver configured to send channel state information to another wireless communication transceiver that precodes transmissions to the transceiver based at least in part on the channel state information, said transceiver including a receiver for receiving signals from the other transceiver and a transmitter for transmitting signals to the other transceiver, including transmitting signals conveying said channel state information, wherein said transceiver is characterized by:

• a memory storing one or more codebooks including entries comprising NTQ different conversion precoders, NT being a number of transmit antenna ports, and Q being an integer value, and entries comprising a number of corresponding tuning precoders, or entries comprising a plurality of overall precoders, with each overall precoder comprising a product of a conversion precoder and a tuning precoder, wherein each said conversion precoder out of said NTQ different entries comprises a block diagonal matrix in which each block comprises a discrete Fourier transform (DFT)-based antenna-subgroup precoder that corresponds to a subgroup of NT transmit antenna ports at the transceiver and provides NTQ different DFT based beams for the corresponding subgroup, transceiver, where Q is an integer value and where the NTQ different conversion precoders, together with one or more of the tuning precoders, correspond to a set of NTQ different overall precoders, wherein each overall precoder represents a size-NT DFT-based beam over the NT transmit antennas ports;
• precoders;
• and
• a precoding feedback generator configured to select entries from the one or more codebooks as a selected conversion precoder and a selected tuning precoder, or as a selected overall precoder corresponding to a selected conversion precoder and a selected tuning precoder;
• said precoding feedback generator further configured to transmit, via said transmitter, indications of the selected entries as precoder information included in said channel state information,
• wherein said one or more codebooks includes conversion and tuning precoders or corresponding overall precoders for multiple transmission ranks, and
• wherein for transmission rank r>2:
• the tuning precoder has 2[r/2] rows and r columns, where r is the transmission rank;
• all of the tuning precoder non-zero elements are constant modulus;
• every column of the tuning precoder has exactly two non-zero elements;
• every row of the tuning precoder has exactly two non-zero elements;
• and
• two columns of the tuning precoder having non-zero elements in the same two rows are orthogonal to each other.

A method of precoding multi-antenna transmissions from a wireless communication transceiver to another wireless communication transceiver, based at least in part on receiving channel state information from the other transceiver that includes precoder information, said method characterized by:

• Identifying the precoder information by selecting entries from one or more codebooks known at the transceiver responsive to selection indications included in the channel state information;
• and
• precoding a transmission to the other transceiver based at least in part on the precoder information;
• wherein the one or more codebooks as known by the transceiver include entries comprising NT Q different conversion precoders, NT being a number of transmit antenna ports and Q being an integer value, and entries comprising a number of corresponding tuning precoders, or entries comprising a plurality of overall precoders, with each overall precoder comprising a product of a conversion precoder and a tuning precoder, and wherein each said conversion precoder out of said NT Q different entries comprises a block diagonal matrix in which each block comprises a discrete Fourier transform (DFT)-based antenna-subgroup precoder that corresponds to a subgroup of NT transmit antenna ports and provides NT Q different DFT based beams for the corresponding subgroup, ports, wherein the NT Q different conversion precoders, together with one or more of the tuning precoders, correspond to a set of NT Q different overall precoders, wherein each overall precoder represents a size- NT DFT-based beam over the NT transmit antenna ports,
• wherein said one or more codebooks includes conversion and tuning precoders or corresponding overall precoders for multiple transmission ranks, and wherein for transmission rank r>2:
• the tuning precoder has 2[r/2] rows and r columns, where r is the transmission rank;
• all non-zero elements of the tuning precoder are constant modulus;
• every column of the tuning precoder has exactly two non-zero elements;
• every row of the tuning precoder has exactly two non-zero elements;
• and
• two columns of the tuning precoder having non-zero elements in the same two rows are orthogonal to each other precoders.

A wireless communication transceiver configured to precode multi-antenna transmissions to another wireless communication transceiver based at least in part on receiving channel state information from the other transceiver, said transceiver including a transmitter and a plurality of antennas for transmitting said multi-antenna transmissions and a receiver for receiving the channel state information, and wherein the transceiver is characterized by:

• a memory storing one or more codebooks including entries comprising NTQ different conversion precoders, NT being a number of transmit antenna ports and Q being an integer value, and entries comprising a number of corresponding tuning precoders, or entries comprising a plurality of overall precoders, with each overall precoder comprising a product of a conversion precoder and a tuning precoder, wherein each said conversion precoder out of said NTQ different entries comprises a block diagonal matrix in which each block comprises a discrete Fourier transform (DFT)-based antenna-subgroup precoder that corresponds to a subgroup of NT transmit antenna ports and provides NTQ different DFT based beams for the corresponding subgroup, ports, where the NTQ different conversion precoders together with one or more of the tuning precoders correspond to a set of NTQ different overall precoders, wherein each overall precoder represents a size- NT DFT-based beam over the NT transmit antenna ports;
• precoders;
• a feedback processor configured to identify precoder information from the other receiver based on using selection indications included in the channel state information to identify from the one or more codebooks selected conversion and tuning precoders or a selected overall precoder corresponding to selected conversion and tuning precoders;
• and
• a precoding controller and associated precoding circuit configured to precode the transmission to the other transceiver, based at least in part on the precoder information,
• wherein said one or more codebooks includes conversion and tuning precoders or corresponding overall precoders for multiple transmission ranks, and
• wherein for transmission rank r>2:
• the tuning precoder has 2[r/2] rows and r columns, where r is the transmission rank;
• all non-zero elements of the tuning precoder are constant modulus;
• every column of the tuning precoder has exactly two non-zero elements;
• every row of the tuning precoder has exactly two non-zero elements, and
• two columns of the tuning precoder having non-zero elements in the same two rows are orthogonal to each other information.