# US 7,609,780 B2 · Method and apparatus for performing sequential closed loop multiple input multiple output (MIMO) > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,780 B2 - Document ID: US7609780B2 - Status: Granted - Kind: B2 - Application number: 10/954,582 - Filed: 2004-09-30 - Published: 2006-04-06 - Granted: 2009-10-27 - Earliest claimed: 2004-09-30 - Assignees: Intel Corporation - Inventors: John S. Sadowsky - Web page: https://patentgrep.com/patent/US7609780B2 ## CPC - H04B 7/0634: {Antenna weights or vector/matrix coefficients} - H04B 7/0617: {for beam forming} - H04B 7/0636: {Feedback format} - H04B 7/0417: Feedback systems - H04B: TRANSMISSION ## Abstract In a communication system using closed loop multiple input/multiple output MIMO, beam forming information may be fed back from a receiver to a transmitter sequentially over a number of frames. The beam forming matrices that are fed back may be quantized. ## Claims ### Claim 1 A wireless device comprising: a beam former to multiply input data symbols by a beam forming matrix to form signals to be directed to multiple antennas for transmission into a MIMO channel as a data frame; a first storage area to store a beam forming matrix that was used by said beam former during generation of a most recently transmitted data frame; a second storage area to store a feedback matrix received from a remote device; and a combiner to combine said beam forming matrix and said feedback matrix to generate an updated beam forming matrix for use by said beam former during generation of a subsequent data frame, wherein said combiner is a multiplication unit that right multiplies said beam forming matrix with said feedback matrix to generate said updated beam forming matrix. ### Claim 2 (depends on 1) The wireless device of claim 1, wherein: said feedback matrix received from said remote device is quantized. ### Claim 3 (depends on 1) The wireless device of claim 1, wherein: said wireless device is for use in a wireless network where data is transmitted in wireless frame exchange sequences, wherein said feedback matrix is received from said remote device as part of a response frame that also includes an acknowledgement packet. ### Claim 4 (depends on 3) The wireless device of claim 3, wherein: said combiner generates updated beam forming matrices for multiple successive data frames transmitted during a frame exchange sequence. ### Claim 5 A wireless device comprising: at least one dipole antenna; a beam former to multiply input data symbols by a beam forming matrix to form signals to be directed to multiple antennas for transmission into a MIMO channel as a data frame, said multiple antennas including said at least one dipole antenna; a first storage area to store a beam forming matrix that was used by said beam former during generation of a most recently transmitted data frame; a second storage area to store a feedback matrix received from a remote device; and a combiner to combine said beam forming matrix and said feedback matrix to generate an updated beam forming matrix for use by said beam former during generation of a subsequent data frame, wherein said combiner is a multiplication unit that right multiplies said beam forming matrix with said feedback matrix to generate said updated beam forming matrix. ### Claim 6 (depends on 5) The wireless device of claim 5, wherein: said combiner is a multiplication unit. ### Claim 7 (depends on 5) The wireless device of claim 5, wherein: said feedback matrix received from said remote device is quantized. ### Claim 8 An article comprising a computer readable storage medium having instructions stored thereon that, when executed by a computing platform, operate to: receive a signal Yi from a MIMO channel, said signal Yi including data symbols Xi that were matrix multiplied by a beam forming matrix Vi within a remote transmitter before being transmitted into said MIMO channel, said MIMO channel having a channel matrix Hi; use said signal Yi to determine a combined channel {tilde over (H)}i that includes effects of both the beam forming matrix Vi and the channel matrix Hi; perform a singular value decomposition (SVD) of the combined channel {tilde over (H)}i to determine a beam forming matrix {tilde over (V)}i representing a correction that is needed for the beam forming matrix Vi; and transmit said beam forming matrix {tilde over (V)}i to said remote transmitter to be multiplied with said beam forming matrix Vi to generate a new beam forming matrix Vi+1 for use in a subsequent data transmission from said remote transmitter. ### Claim 9 (depends on 8) The article of claim 8, wherein said instructions further operate to: quantize said beam forming matrix {tilde over (V)}i before it is transmitted. ### Claim 10 (depends on 8) The article of claim 8, wherein said instructions further operate to: quantize said beam forming matrix {tilde over (V)}i using vector quantization techniques before said beam forming matrix {tilde over (V)}i is transmitted. ### Claim 11 (depends on 8) The article of claim 8, wherein said instructions further operate to: quantize said beam forming matrix {tilde over (V)}i using adaptive quantization techniques before said beam forming matrix {tilde over (V)}i is transmitted. ### Claim 12 A wireless device comprising: a plurality of antennas; and a digital processing device to support communication with a remote wireless device via a multiple input/multiple output (MIMO) channel, said digital processing device being programmed to: receive a signal Yi from said MIMO channel, said signal Yi including data symbols Xi that were matrix multiplied by a beam forming matrix Vi within a transmitter of said remote wireless device before being transmitted into said MIMO channel, said MIMO channel having a channel matrix Hi; use said signal Yi to determine a combined channel {tilde over (H)}i that includes effects of both the beam forming matrix Vi and the channel matrix Hi; perform singular value decomposition (SVD) of the combined channel {tilde over (H)}i to determine a beam forming matrix {tilde over (V)}i representing a correction that is needed for the beam forming matrix Vi; and transmit said beam forming matrix {tilde over (V)}i to said remote wireless device to be multiplied with said beam forming matrix Vi to generate a new beam forming matrix Vi+1 for use in a subsequent data transmission from said remote wireless device. ### Claim 13 (depends on 12) The wireless device of claim 12, wherein: said communication with said remote wireless device includes a frame exchange sequence with said remote wireless device; and receive, use, perform, and transmit are repeated for multiple successive data frames received during said frame exchange sequence. ### Claim 14 (depends on 12) The wireless device of claim 12, wherein: said communication with said remote wireless device includes a frame exchange sequence with said remote wireless device; and transmission of said beam forming matrix {tilde over (V)}i to said remote wireless device includes transmitting said beam forming matrix {tilde over (V)}i as part of a response frame that also includes an acknowledgement packet. ### Claim 15 (depends on 12) The wireless device of claim 12, wherein said digital processing device is programmed to: quantize said beam forming matrix {tilde over (V)}i before transmitting it to said remote wireless device. ### Claim 16 (depends on 12) The wireless device of claim 12, wherein said digital processing device is programmed to: quantize said beam forming matrix {tilde over (V)}i using vector quantization techniques before transmitting it to said remote wireless device. ### Claim 17 (depends on 12) The wireless device of claim 12, wherein said digital processing device is programmed to: quantize said beam forming matrix {tilde over (V)}i using Grassmanian beam forming techniques before transmitting it to said remote wireless device. ### Claim 18 (depends on 12) The wireless device of claim 12, wherein said digital processing device is programmed to: quantize said beam forming matrix {tilde over (V)}i using adaptive quantization techniques before transmitting it to said remote wireless device. ### Claim 19 (depends on 12) The wireless device of claim 12, wherein said digital processing device is programmed to: quantize said beam forming matrix {tilde over (V)}i using differential quantization techniques before transmitting it to said remote wireless device.