# US 8,542,589 B2 · Method and apparatus for providing beamforming feedback in wireless communication systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,589 B2 - Document ID: US8542589B2 - Status: Granted - Kind: B2 - Application number: 11/753,798 - Filed: 2007-05-25 - Published: 2008-02-21 - Granted: 2013-09-24 - Earliest claimed: 2006-06-05 - Assignees: QUALCOMM Incorporated - Applicants: Shravan K. Surineni; J. Rodney Walton; Mark S. Wallace; Steven J. Howard - Inventors: Shravan K. Surineni; J. Rodney Walton; Mark S. Wallace; Steven J. Howard - Web page: https://patentgrep.com/patent/US8542589B2 ## CPC - H04B 7/0636: {Feedback format} - H04B 7/0417: Feedback systems - H04B 7/0634: {Antenna weights or vector/matrix coefficients} - H04L 1/1671: {the supervisory signal being transmitted together with control information} - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Techniques for quickly sending feedback information for beamforming are described. A transmitter/initiator sends a first frame comprising training symbols. A receiver/responder receives the first frame, determines the amount of time to generate feedback information, and determines the amount of time to send the feedback information. The receiver then determines the length of a second frame carrying the feedback information based on the amounts of time to generate and send the feedback information. The receiver sends the second frame after waiting a short interframe space (SIFS) period from the end of the first frame, without performing channel access. The receiver generates the feedback information based on the training symbols and sends the information in the second frame when ready. The transmitter receives the second frame, derives at least one steering matrix based on the feedback information, and sends a third frame with the at least one steering matrix. ## Claims ### Claim 1 An apparatus comprising: a processor configured to receive a first frame comprising training symbols, to determine an amount of time to generate feedback information based on the training symbols in the first frame, and to generate a second frame, the second frame having a length determined prior to generating the feedback information based at least on the determined amount of time to generate the feedback information and the second frame having a second portion, the first portion having a length equal to or exceeding the amount of time to generate the feedback information, the second portion carrying the feedback information; and a memory coupled to the processor. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the processor is configured to identify a type of feedback information to generate from among multiple feedback information types, and to determine the amount of time to generate the feedback information based on the type of feedback information to generate. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the processor is configured to determine an amount of time to send the feedback information and to determine the length of the second frame based further on the amount of time to send the feedback information. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein the processor is configured to determine a data rate for the second frame, to identify type of feedback information to send from among multiple feedback information types, and to determine the amount of time to send the feedback information based on the data rate and the type of feedback information to send. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein the processor is configured to form an aggregate Medium Access Control (MAC) protocol data unit (A-MPDU) comprising multiple MPDUs, and to generate the second frame with the A-MPDD. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein the processor is configured to form the A-MPDU with a first set of at least one MPDU followed by a second set of at least one MPDU, the first set of at least one MPDU having a length equal to or exceeding the amount of time to generate the feedback information, and to provide the feedback information in the second set of at least one MPDD. ### Claim 7 (depends on 5) The apparatus of claim 5, wherein the processor is configured to form a first MPDU having a length equal to or exceeding the amount of time to generate the feedback information, to form a second MPDU with the feedback information, and to form the A-MPDU with the first MPDU followed by the second MPDD. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the processor is configured to wait a short interframe space (SIFS) period after the end of the first frame and to send the second frame after waiting the SIFS period and without performing channel access. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein the processor is configured to derive at least one channel matrix based on the training symbols in the first frame, and to generate the feedback information based on the at least one channel matrix. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein the processor is configured to derive at least one channel matrix based on the training symbols in the first frame, to derive at least one beamforming matrix based on the at least one channel matrix, and to generate the feedback information based on the at least one beamforming matrix. ### Claim 11 (depends on 1) The apparatus of claim 1, wherein the feedback information comprises at least one compressed beamforming matrix. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein the feedback information comprises channel state information (CSI). ### Claim 13 (depends on 1) The apparatus of claim 1, wherein the processor is configured to set a length field of the second frame to the length of the second frame. ### Claim 14 A method comprising: receiving a first frame comprising training symbols; determining an amount of time to generate feedback information based on the training symbols in the first frame; and sending a second frame for the feedback information, the second frame having a length determined prior to generating the feedback information based at least on the amount of time to generate the feedback information and the second frame having a second portion, the first portion having a length equal to or exceeding the amount of time to generate the feedback information, the second portion carrying the feedback information. ### Claim 15 (depends on 14) The method of claim 14, further comprising: determining amount of time to send the feedback information; and determining the length of the second frame based further on the amount of time to send the feedback information. ### Claim 16 (depends on 14) The method of claim 14, further comprising: generating the second frame with a first portion followed by a second portion, the first portion having a length equal to or exceeding the amount of time to generate the feedback information, the second portion carrying the feedback information. ### Claim 17 (depends on 14) The method of claim 14, wherein the sending the second frame comprises waiting a short interframe space (SIFS) period after the end of the first frame, and sending the second frame after waiting the SIFS period and without performing channel access. ### Claim 18 An apparatus comprising: means for receiving a first frame comprising training symbols; means for determining an amount of time to generate feedback information based on the training symbols in the first frame; and means for sending a second frame for the feedback information, the second frame having a length determined prior to generating the feedback information based at least on the amount of time to generate the feedback information and the second frame having a second portion, the first portion having a length equal to or exceeding the amount of time to generate the feedback information, the second portion carrying the feedback information. ### Claim 19 (depends on 18) The apparatus of claim 18, further comprising: means for determining amount of time to send the feedback information; and means for determining the length of the second frame based further on the amount of time to send the feedback information. ### Claim 20 (depends on 18) The apparatus of claim 18, further comprising: means for generating the second frame with a first portion followed by a second portion, the first portion having a length equal to or exceeding the amount of time to generate the feedback information, the second portion carrying the feedback information. ### Claim 21 (depends on 18) The apparatus of claim 18, wherein the means for sending the second frame comprises means for waiting a short interframe space (SIFS) period after the end of the first frame, and means for sending the second frame after waiting the SIFS period and without performing channel access. ### Claim 22 A computer-program product for regulating the receipt of data transmitted from a messaging device, the computer-program product comprising: a processor-readable storage device including instructions stored thereon, the instructions comprising: first instructions for receiving a first frame comprising training symbols; second instructions for determining an amount of time to generate feedback information based on the training symbols in the first frame; and third instructions for sending a second frame for the feedback information, the second frame having a length determined prior to generating the feedback information based at least on the amount of time to generate the feedback information and the second frame having a second portion, the first portion having a length equal to or exceeding the amount of time to generate the feedback information, the second portion carrying the feedback information. ### Claim 23 (depends on 22) The computer-program product of claim 22, wherein the instructions further comprise: fourth instructions for determining amount of time to send the feedback information; and fifth instructions for determining the length of the second frame based further on the amount of time to send the feedback information. ### Claim 24 (depends on 22) The computer-program product of claim 22, wherein the instructions further comprise: fourth instructions for generating the second frame with a first portion followed by a second portion, the first portion having a length equal to or exceeding the amount of time to generate the feedback information, the second portion carrying the feedback information. ### Claim 25 An apparatus comprising: a processor configured to send a first frame comprising training symbols, to receive a second frame comprising a first portion followed by a second portion, the first portion having a length determined prior to a generation of feedback information at a receiver of the first frame based on a predetermined amount of time associated with generating the feedback information by the receiver of the first frame, the second frame having a second portion, the first portion having a length equal to or exceeding the amount of time to generate the feedback information, the second portion carrying the feedback information; to derive at least one steering matrix based on the feedback information obtained from the second frame; and a memory coupled to the processor. ### Claim 26 (depends on 25) The apparatus of claim 25, wherein the processor is configured to receive from the second frame an aggregate Medium Access Control (MAC) protocol data unit (A-MPDU) comprising a first MPDU for the first portion and a second MPDU for the second portion. ### Claim 27 (depends on 25) The apparatus of claim 25, wherein the processor is configured to obtain at least one channel matrix from the feedback information, to derive at least one beamforming matrix based on the at least one channel matrix, and to derive the at least one steering matrix based on the at least one beamforming matrix. ### Claim 28 (depends on 25) The apparatus of claim 25, wherein the processor is configured to obtain at least one beamforming matrix from the feedback information, and to derive the at least one steering matrix based on the at least one beamforming matrix. ### Claim 29 (depends on 25) The apparatus of claim 25, wherein the processor is configured to receive the second frame after a short interframe space (SIFS) period from the end of the first frame. ### Claim 30 (depends on 25) The apparatus of claim 25, wherein the processor is configured to perform transmit spatial processing for a third frame based on the at least one steering matrix, and to send the third frame to the receiver. ### Claim 31 A method comprising: sending a first frame comprising training symbols; receiving a second frame comprising a first portion followed by a second portion, the first portion having a length determined prior to a generation of feedback information at a receiver of the first flame based on a predetermined amount of time associated with generating the feedback information by the receiver of the first frame, the first portion having a length equal to or exceeding the amount of time to generate the feedback information, the second portion carrying the feedback information; and deriving at least one steering matrix based on the feedback information obtained from the second frame. ### Claim 32 (depends on 31) The method of claim 31, wherein the deriving the at least one steering matrix comprises obtaining at least one channel matrix from the feedback information, deriving at least one beamforming matrix based on the at least one channel matrix, and deriving the at least one steering matrix based on the at least one beamforming matrix. ### Claim 33 (depends on 31) The method of claim 31, wherein the deriving the at least one steering matrix comprises obtaining at least one beamforming matrix from the feedback information, and deriving the at least one steering matrix based on the at least one beamforming matrix. ### Claim 34 An apparatus comprising: means for sending a first frame comprising training symbols; means for receiving a second frame comprising a first portion followed by a second portion, the first portion having a length determined prior to a generation of feedback information at a receiver of the first frame based on a predetermined amount of time associated with generating the feedback information by the receiver of the first frame, the first portion having a length equal to or exceeding the amount of time to generate the feedback information, the second portion carrying the feedback information; and means for deriving at least one steering matrix based on the feedback information obtained from the second frame. ### Claim 35 (depends on 34) The apparatus of claim 34, wherein the means for deriving the at least one steering matrix comprises means for obtaining at least one channel matrix from the feedback information, means for deriving at least one beamforming matrix based on the at least one channel matrix, and means for deriving the at least one steering matrix based on the at least one beamforming matrix. ### Claim 36 (depends on 34) The apparatus of claim 34, wherein the means for deriving the at least one steering matrix comprises means for obtaining at least one beamforming matrix from the feedback information, and means for deriving the at least one steering matrix based on the at least one beamforming matrix. ### Claim 37 A computer-program product for regulating the receipt of data transmitted from a messaging device, the computer-program product comprising: a processor-readable storage device including instructions stored thereon, the instructions comprising: first instructions for sending a first frame comprising training symbols; second instructions for receiving a second frame comprising a first portion followed by a second portion, the first portion having a length determined prior to a generation of feedback information at a receiver of the first frame by an amount of time to generate the feedback information by the receiver of the first frame, the first portion having a length equal to or exceeding the amount of time to generate the feedback information, the second portion carrying the feedback information; and third instructions for deriving at least one steering matrix based on the feedback information obtained from the second frame. ### Claim 38 An apparatus comprising: a processor configured to receive a first frame requesting for feedback information for beamforming, to select one of multiple types of preamble based on a determined amount of time to generate the feedback information for the first frame, and to send a second frame with a preamble of the selected type and including the feedback information, the second frame having a length determined prior to generating the feedback information based at least on the determined amount of time to generate the feedback information and the second frame having a second portion, the first portion having a length equal to or exceeding the amount of time to generate the feedback information, the second portion carrying the feedback information; and a memory coupled to the processor. ### Claim 39 (depends on 38) The apparatus of claim 38, wherein the processor is configured to determine a frame type of the first frame based on a preamble for the first frame, and to select the preamble type for the second frame based on the frame type of the first frame. ### Claim 40 (depends on 38) The apparatus of claim 38, wherein the processor is configured to determine the amount of time to generate feedback information based on training symbols in the first frame. ### Claim 41 (depends on 38) The apparatus of claim 38, wherein the processor is configured to select a mixed-mode preamble or a greenfield preamble for the second frame.