Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 1 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 1 of 22
`
`EXHIBIT (cid:38)
`EXHIBIT C
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 2 of 22
`HeeATTA
`
`US007564914B2
`
`a2) United States Patent
`US 7,564,914 B2
`(0) Patent No.:
`Jul. 21, 2009
`(45) Date of Patent:
`Hansenet al.
`
`METHOD AND SYSTEM FOR FRAME
`FORMATS FOR MIMO CHANNEL
`MEASUREMENT EXCHANGE
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`(54)
`
`(75)
`
`Inventors: Christopher J. Hansen, Sunnyvale, CA
`(US); Carlos H. Aldana, Mountain
`View, CA (US); Joonsuk Kim,San Jose,
`CA (US)
`
`(73)
`
`Assignee: Broadcom Corporation, Irvine, CA
`(US)
`
`(*)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 747 days.
`
`(21)
`
`Appl. No.: 11/052,353
`
`(22)
`
`Filed:
`
`Feb. 7, 2005
`
`(65)
`
`Prior Publication Data
`
`US 2006/0126752 Al
`
`Jun. 15, 2006
`
`Related U.S. Application Data
`
`(60)
`
`Provisional application No. 60/636,255, filed on Dec.
`14, 2004.
`
`(51)
`
`Int. Cl.
`
`(52)
`(58)
`
`(2006.01)
`HO4B 7/02
`(2006.01)
`HO4B 7/216
`US: Gli
`seees nesses 375/267; 370/342
`Field of Classification Search.
`................. 375/267,
`375/260, 295, 299, 346, 347; 455/69, 115.1,
`455/424, 562.1; 370/342, 352, 329
`See application file for complete search history.
`
`.......... 455/115.1
`6/2004 Harrison et al.
`6,754,475 B1*
`7,123,887 B2* 10/2006 Kimetal. oe 455/103
`2005/0099975 Al*
`5/2005 Catreux et al. 0... 370/329
`
`OTHER PUBLICATIONS
`
`Christopher J. Hansen, IEEE 802.11 Wireless LANs WWiSEPro-
`posal: High Throughput Extension to the 802.11 Standard, Dec. 20,
`2004.
`
`Syed AON Mujtaba, IEEE 802.11 Wireless LANs TGn Sync Pro-
`posal Technical Specification, Jan. 18, 2005.
`
`* cited by examiner
`
`Primary Examiner—Khai Tran
`(74) Attorney, Agent, or Firm—McAndrews, Held & Malloy
`
`(57)
`
`ABSTRACT
`
`A method and system for frame formats for MIMO channel
`measurement exchangeis provided. Aspects of a method for
`communicating information in a communication system may
`comprise transmitting data via a plurality of radio frequency
`(RF) channels utilizing a plurality of transmitting antenna,
`receiving feedback informationviaat least one of a plurality
`of RF channels, and modifying a transmission mode based on
`the feedback information. Aspects of a method for commu-
`nicating information in a communication system may also
`comprise receiving data via a plurality of receiving antenna,
`transmitting feedback information via at least one of the
`plurality of RF channels, and requesting modification of a
`transmission mode for the received data in transmitted
`
`response messages comprising the feedback information.
`
`36 Claims, 9 Drawing Sheets
`
`814
`
`S
`S
`Transmitting Mobile Terminal
`Receiving Mobile Terminal
`
`
`
`Receives MIMO Channel
`Sends MIMO Channel Request
`Frame to Receiving Mobile
`Request Frame from
`
`Terminal
`Transmitting Mobile Terminal
`Receiving Mobile
`Terminal Sends Null
`Response?
`
`
`
`Receiving Mobile Terminal
`
`
`Transmits MIMO Channe!
`
`Response Frameto
`
`Transmitting Mobile Terminal
`Containing Null Channel
`Information
`
`
`
`
`
`08
`
`
`Receiving MobileTerminal Sends
`Complete Channel
`Response?
`
`
`S
`Receiving Mobile Terminal Transmits
`MIMO Channel Response Frameto
`Transmitting Mobile Terminal
`Containing # of Rows, # of Columns,
`and Complete ChannelEstimate Matrix
`Computed During Processing of
`Preamble Field in MIMO Channel
`Request Frame
`
`
`
`Receiving Mobile
`Terminal Computes
`Complete Channel
`Estimate Matrix Based on
`PreambleField in MIMO.
`Channel Request Frame
`816
`
`Receiving Mobile
`Terminal Computes
`Matrix Decomposition on
`Complete Channel
`Estimate Matrix
`
`
`
`
`Receiving Mobile Terminal Transmits
`MIMO ChannelResponse Frameto
`‘Transmitting Mobile Terminal
`Containing # of Rows, # of Columns,
`Right Singular Vector Matrix, and
`DiagonalMatrix of Singular Values
`
`
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 3 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 3 of 22
`
`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 1 of 9
`
`US 7,564,914 B2
`
`DecodingProcessor
`
`FIG.1
`
`
`
` emappingADemodulation
`Demarping
`
`122
`
`
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 4 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 4 of 22
`
`Sheet 2 of 9
`
`US 7,564,914 B2
`
`U.S. Patent
`
`Jul. 21, 2009
`
`FIG.2
`
`
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 5 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 5 of 22
`
`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 3 of 9
`
`US 7,564,914 B2
`
` 308
`
`ModeRequest 4
`
`306
`
` 1DialogToken
`
`
`304
`
`FIG.3
`
`
`
`302
`
`
`Category {
`
`300
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 6 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 6 of 22
`
`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 4 of 9
`
`US 7,564,914 B2
`
`
`
`ModeResponse 4
`
`
`
`1
`
`Gao_ +
`
`7]
`
`FIG.4
`
`22o
`
`O
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 7 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 7 of 22
`
`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 5 of 9
`
`US 7,564,914 B2
`
`FIG.5
`
`O==
`
`DB
`®D
`
`3o
`
`>
`®@
`or
`
`@cc o
`
`c O o
`
`
`
`DialogToken
`
`508
`
`506
`
`504
`
`502
`
`500
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 8 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 8 of 22
`
`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 6 of 9
`
`US 7,564,914 B2
`
`FIG.6a
`
` 608
`
`MIMOChannelResponse N
`
`
`606
`
` 1DialogToken
`
`
`604
`
`602
`
`600
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 9 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 9 of 22
`
`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 7 of 9
`
`US 7,564,914 B2
`
`XIREWSJeUysa
`
`=adh
`jauueyDaje}dwogSULUN|OD#WBUUEYD9}>|Oe
`
`
`
`auayajdwo
`
`=9GAL q9Sid
`sane,senbuisXUJEWjeuUeYD
`
`
`yoXWEWloanseinBulsjyBrySuetpaonpedlGAS.
`
`
`
`99°Dl4
`
`aliNN,,=@dAL
`
`P9"SIs
`
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 10 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 10 of 22
`
`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 8 of 9
`
`US 7,564,914 B2
`
`racy
`
`
`
`
`
`jeulUd,a1qowSumwsues)
`
`
`
`ysanbayapowOWIWSpues
`
`
`
`aqoyyBuiaiaooy0}euel4
`
`jeu)
`
`SaAalIqowBuinreoay
`
`
`
`SOUIWUII}OQ[BUI
`
`
`
`Zapow-SuwsuesL
`
`
`
`ysonboyopowOWIIWSeaisooy
`
`jeuluua|aIqoWBunywusuerwoyewes4
`
`
`
`
`
`JeulWUayaiqoyyBuiaisooy
`
`
`
`
`
`jeulUUaaigoyyBuiaisoay
`
`POWOWIIWSilusues
`
`
`
`0}awes4asuodsey
`
`
`
`
`
`JEUILUE]Sqo;Bunywusues
`
`
`
`Jeulwua,aiqowBuiaisoay
`
`SPOWOWIWS}Wwisuely
`
`
`
`0}swel4asuodsey
`
`
`
`
`
`yeulue,sqoywSuniusues,
`
`yoeqpee4Bujuleyu0y
`
`paiiseguoUOeLUWUOJU]
`
`
`
`epoy;Suipiusuesy
`
`yoeqpeeonBuluieyuoD
`
`paviseguouoHeWWOU]
`
`
`
`opoyySuljwusuesL
`
`Z‘Sla
`
`
`
`
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 11 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 11 of 22
`
`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 9 of 9
`
`US 7,564,914 B2
`
`908
`
`808
`
`
`
`So,SIIqOWBuiarsooy
`
`ON
`
`
`
`IINNSpuagseule,
`
`Eesuodsay
`
`
`
`
`
`JeuiuuayayiqoyBuinracay
`
`
`
`jeurwuea)aqowBunyusuedy
`
`
`
`0}swiel4asuodsay
`
`
`
`jauueYydOWIsilwsuesLols
`
`08
`
`
`
`
`
`Woyswes4ysonbay
`
`
`
`jauueydJINNBujwequ0g
`
`
`
`[eUILuJe|LOREUUOIUTSOAaIqowBuniasey
`
`spuas
`
`ON
`
`
`
`sjlwsuel]|euIUUa!aliqoyyBuiiaoay
`
`
`
`
`
`
`
`
`
`0}awes4asucdsayjauUeYDOWI
`
`
`
`
`
`JeuuueyarqoyyBunywsuesL
`
`‘SuUUN|ODJO#‘SMOYJO#BulUIE}UCD
`
`Z1e
`
`
`
`jauueygajejdiuog
`
`gZasuodsay
`
`
`
`
`
`XUJEYYAJBLUSyjaUUeYDsyJejdwoDdpue
`
`
`
`
`
`
`
`
`
`JoBuisseooigBulingpayndwod
`
`[BUUEYDOWIU!pledeiquiesid
`
`
`
`ewel4jsenbey
`
`8‘Sid
`
`
`
`
`
`JEUILUALS[.GOWBulAleooy
`
`JOUUBUDOWIINSOAISOOY
`
`SIGOWBunusuesy 208
`
`
`
`Jeuluue]spqowBugwsuers
`
`
`
`DIIGOWBulaisoay0}wey
`
`Jeulwud)
`
`
`
`algo;Buniaoey
`
`
`
`sayndwosjeulwmues
`
`
`
`jauueyyayajdwo>
`
`uopasegXueeyeusy
`
`
`
`OWIWUIpietye1QWead
`
`¥L8
`
`
`
`
`
`auwel4enbeyjeuueyd
`
`
`
`ajiqoyyBurarasay
`
`
`
`sayndwogjeuiuuaL
`
`
`
`uouolIsodwosagxjeyy
`
`
`
`jauueyyazajdwes
`
`XESyBwysy
`
`9t8
`
`Ste
`
`
`
`
`
`
`
`syWsuelJeulUUa)aiqoyyBuiaeoay
`
`
`
`
`
`
`
`0}aweJ4asuodsayJaUUEYDOWIW
`
`
`
`
`
`JeulUe)siqoy)Buyiusuesy
`
`‘SULUNJODJo#‘SmOYJo#BulUlEJUOD
`
`
`
`
`
`pue‘xyeyyJoaJeinBuisYyHrRy
`
`
`
`
`
`sane,JeinBusJoxuyeywjeuobeiq
`
`
`
`
`
`JeuIUUa)
`
`
`
`
`
`ysanbayjauueUDOWISpues
`
`
`
`
`
`
`
`
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 12 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 12 of 22
`
`US 7,564,914 B2
`
`1
`METHOD AND SYSTEM FOR FRAME
`FORMATS FOR MIMO CHANNEL
`MEASUREMENT EXCHANGE
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS/INCORPORATION BY
`REFERENCE
`
`This application makesreferenceto, claimspriority to, and
`claims the benefit of U.S. Provisional Application Ser. No.
`60/636255 filed Dec. 14, 2004.
`This application also makes reference to U.S. patent appli-
`cation Ser. No. 11/052,389 filed Feb. 7, 2005.
`All of the above stated applications are hereby incorpo-
`rated herein in their entirety.
`
`FIELD OF THE INVENTION
`
`Certain embodiments of the invention relate to wireless
`
`networking. More specifically, certain embodiments of the
`invention relate to a method and system for frame formats for
`MIMOchannel measurement exchange.
`
`BACKGROUND OF THE INVENTION
`
`The Institute for Electrical and Electronics Engineers
`(IEEE), in resolution IEEE 802.11, also referred as “802.11”,
`has defined a plurality of specifications which are related to
`wireless networking. Among them are specifications for
`“closed loop” feedback mechanisms by which a receiving
`mobile terminal may feed back information to a transmitting
`mobile terminalto assist the transmitting mobile terminal in
`adapting signals which are sent to the receiving mobile ter-
`minal.
`
`Smart antenna systems combine multiple antenna ele-
`ments with a signal processing capability to optimize the
`pattern of transmitted signal radiation and/or reception in
`response to the communications medium environment. The
`process of optimizing the pattern of radiation is sometimes
`referred to as “beamforming,” which mayutilize linear array
`mathematical operations to increase the average signal to
`noise ratio (SNR) by focusing energy in desired directions. In
`conventional smart antenna systems, only the transmitter or
`the receiver may be equipped with more than one antenna,
`and may typically be located in the base transceiver station
`(BTS) where the cost and space associated with smart
`antenna systems have been perceived as more easily afford-
`able than on mobile terminals such as cellular telephones.
`Such systemsare also known as multiple input single output
`(MISO) when a multiple antenna transmitter is transmitting
`signals to a single antenna receiver, or single input multiple
`output (SIMO) when a multiple antenna receiveris receiving
`signals that have been transmitted from a single antenna
`transmitter. With advancesin digital signal processing (DSP)
`integrated circuits (ICs) in recent years, multiple antenna
`multiple output (MIMO) systems have emerged in which
`mobile terminals incorporate smart antenna systems compris-
`ing multiple transmit antenna and multiple receive antenna.
`Onearea of early adoption of MIMO systemshas beenin the
`field of wireless networking, particularly as applied to wire-
`less local area networks (WLANs) wheretransmitting mobile
`terminals communicate with receiving mobile terminals.
`IEEEresolution 802.11 comprises specifications for commu-
`nications between mobile terminals in WLAN systems.
`Signal fading is a significant problem in wireless commu-
`nications systems, often leading to temporary loss of commu-
`nications at mobile terminals. One of the most pervasive
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`forms of fading is known as multipath fading, in which dis-
`persion oftransmitted signals due to incidentreflections from
`buildings and other obstacles, results in multiple versions of
`the transmitted signals arriving at a receiving mobile termi-
`nal. The multiple versions ofthe transmitted signal mayinter-
`fere with each other and mayresult in a reduced signallevel
`detected at the receiving mobile terminal. When versions of
`the transmitted signal are 180° out of phase they may cancel
`each other such that a signal level of 0 is detected. Locations
`where this occurs may correspondto “dead zones” in which
`communication to the wireless terminal is temporarilylost.
`This type of fading is also known as “Rayleigh”or “flat”
`fading.
`A transmitting mobile terminal may transmit data signals
`in which data is arranged as “symbols”. The transmission of
`symbols may be constrained suchthat after a symbolis trans-
`mitted, a minimum period of time, T,, must transpire before
`another symbol may betransmitted. After transmission of a
`symbol from a transmitting mobile terminal, some period of
`dispersion time, T,, may transpire which maybe the time over
`which the receiving mobile terminal is able to receive the
`symbol, including multipath reflections. The time T,, may not
`need to account for the arrival of all multipath reflections
`becauseinterference from laterarriving reflected signals may
`be negligible. If the period T, is less than T, there is a possi-
`bility that the receiving mobile terminal will start receiving a
`second symbolfrom the transmitting mobile terminal while it
`is still receiving the first symbol. This may result in inter-
`symbolinterference (ISI), producing distortion in received
`signals, and possibility resulting in a loss of information. The
`quantity 1/Tis also referred to as the “coherence bandwidth”
`which mayindicate the maximum rate at which symbols, and
`correspondingly information, may be transmitted via a given
`communications medium. One method to compensate for ISI
`in signals mayentail utilizing DSP algorithms which perform
`adaptive equalization.
`Another important type of fading is related to motion.
`Whena transmitting mobile terminal, or a receiving mobile
`terminal is in motion, the Doppler phenomenon mayaffect
`the frequency of the received signal. The frequency of the
`received signal may be changed by an amount which is a
`function ofthe velocity at which a mobile terminalis moving.
`Because of the Doppler effect, ISI may result when a mobile
`terminalis in motion, particularly when the mobile terminalis
`moving at a high velocity. Intuitively, if a receiving mobile
`terminal is in motion and nearing a transmitting mobileter-
`minal, the distance between the two mobile terminals will
`change as a function of time. As the distance is reduced, the
`propagation delay time, T,,, which is the time between when
`a transmitterfirst transmits a signal and whenitfirst arrives at
`a receiver, is also reduced. As the mobile terminals become
`closer it is also possible that T, may be increased if, for
`example, the transmitting mobile terminal does not reduce the
`radiated poweroftransmitted signals. IfT,, becomesless than
`T.,, there may be ISI due to the Doppler effect. This case,
`whichillustrates why data rates may be reduced for mobile
`terminals that are in motion, is referred to as “fast fading”.
`Because fast fading may distort signals at some frequencies
`while not distorting signals at other frequencies, fast fading
`mayalso be referred to as “frequency selective” fading.
`Smart antenna systems may transmit multiple versions of a
`signal in what is knownas “spatial diversity”. A key concept
`in spatialdiversity is that the propagation ofmultiple versions
`of a signal, or “spatial stream”, from different antenna may
`significantly reduce the probability offlat fading at the receiv-
`ing mobile terminal since notall of the transmitted signals
`would have the same dead zone.
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 13 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 13 of 22
`
`US 7,564,914 B2
`
`3
`Current transmission schemes in MIMO systemstypically
`fall into two categories: data rate maximization, and diversity
`maximization. Data rate maximization focuses on increasing
`the aggregate data transfer rate between a transmitting mobile
`terminal and a receiving mobile terminal by transmitting
`different spatial streams from different antenna. One method
`for increasing the data rate from a transmitting mobile termi-
`nal would be to decomposea highbit rate data stream into a
`plurality of lowerbit rate data streams such that the aggregate
`bit rates amongthe plurality of lowerbit rate data streamsis
`equalto that of the high bit rate data stream. Next, each of the
`lowerbit rate data streams may be mappedto at least one of
`the transmitting antenna for transmission. In addition, each
`signal comprising one of the lower bit rate data streams is
`multiplicatively scaled by a weighting factor prior to trans-
`mission. The plurality of multiplicative scale factors applied
`to the plurality of signals comprising the lower bit rate data
`streams maybeutilized to form the transmitted “beam”in the
`beamforming technique. An example of a data rate maximi-
`zation schemeis orthogonal frequency division multiplexing
`(OFDM), in which each ofthe plurality of signals is modu-
`lated by a different frequencycarrier signal prior to mapping
`and multiplicative scaling. OFDM transmission mayberesis-
`tant to multipath fading in that a portion, but mostlikely not
`all, of the data transmitted maybe lost at any instant in time
`due to multipath fading.
`Diversity maximization focuses on increasing the prob-
`ability that a signal transmitted by a transmitting mobile
`terminal will be received at a receiving mobile terminal, and
`on increasing the SNR of receivedsignals. In diversity maxi-
`mization, multiple versions of the same signal maybetrans-
`mitted by a plurality of antenna. The case in which a trans-
`mitting mobile terminalis transmitting the samesignalviaall
`of its transmitting antenna may be the pure spatial diversity
`case in which the aggregate data transfer rate may be equal to
`that ofa single antenna mobile terminal. There is a plurality of
`hybrid adaptations ofthe data rate and spatial diversity maxi-
`mization schemes which achieve varying data rates and spa-
`tial diversities.
`
`MIMOsystems employing beamforming may enable the
`simultaneous transmission of multiple signals occupying a
`shared frequency band, similar to what may be achieved in
`code division multiple access
`(CDMA)
`systems. For
`example, the multiplicative scaling of signals prior to trans-
`mission, and a similar multiplicative scaling of signals after
`reception, may enable a specific antennaat a receiving mobile
`terminal to receive a signal which had been transmitted by a
`specific antenna at the transmitting mobile terminal to the
`exclusion of signals which had been transmitted from other
`antenna. However, MIMO systems may not require the fre-
`quency spreading techniques used in CDMA transmission
`systems. Thus, MIMO systems may make moreefficient uti-
`lization of frequency spectrum.
`Oneofthe challenges in beamformingis that the multipli-
`cative scale factors which are applied to transmitted and
`received signals may be dependent uponthe characteristics of
`the communications medium between the transmitting
`mobile terminal and the receiving mobile terminal. A com-
`munications medium,such as a radio frequency (RF) channel
`between a transmitting mobile terminal and a receiving
`mobile terminal, may be represented by a transfer system
`function, H. The relationship between a time varying trans-
`mitted signal, x(t), a time varying receivedsignal, y(t), and the
`systems function may be represented as shown in equation
`[1l:
`
`Y(O=Hxx())+n(f), where
`
`equation[1]
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`n(t) represents noise which may be introducedas the signal
`travels through the communications medium andthe receiver
`itself. In MIMOsystems, the elements in equation[1] may be
`represented as vectors and matrices. If a transmitting mobile
`terminal comprises M transmitting antenna, and a receiving
`mobile terminal comprises N receiving antenna, then y(t)
`mayberepresented by a vector of dimensions Nx1, x(t) may
`be represented by a vector of dimensions Mx1, n(t) by a
`vector of dimensions Nx1, and H may berepresented by a
`matrix of dimensions NxM.In the case of fast fading, the
`transfer function, H, may itselfbecome time varying and may
`thus also become a function of time, H(t). Therefore, indi-
`vidual coefficients, h,(t), in the transfer function H(t) may
`become time varying in nature.
`In MIMOsystems which communicate according to speci-
`fications in IEEE resolution 802.11, the receiving mobile
`terminal may compute H(t) each time a frame of information
`is received from a transmitting mobile terminal based upon
`the contents of a preamblefield in each frame. The computa-
`tions which are performed at the receiving mobile terminal
`may constitute an estimate of the “true” values of H(t) and
`may be known as “channelestimates”. For a frequency selec-
`tive channel there may be a set of H(t) coefficients for each
`tonethat is transmitted via the RF channel. To the extent that
`
`H(t), which may be referred to as the “channel estimate
`matrix”, changes with time and to the extent that the trans-
`mitting mobile terminalfails to adapt to those changes,infor-
`mation loss between the transmitting mobile terminal and the
`receiving mobile terminal mayresult.
`Higher layer communications protocols, such as the trans-
`mission control protocol (TCP) may attempt to adapt to
`detected informationlosses, but such adaptations maybeless
`than optimal and mayresult in slower information transfer
`rates. In the case of fast fading, the problem may actually
`reside at lower protocol layers, such as the physical (PHY)
`layer, and the media access control (MAC)layer. These pro-
`tocol layers may be specified under IEEE 802.11 for WLAN
`systems. The method by which adaptations may be made at
`the PHY and MAClayers, however, may comprise a mecha-
`nism by which a receiving mobile terminal may provide feed-
`back information to a transmitting mobile terminal based
`upon channel estimates which are computedat the receiving
`mobile terminal.
`
`Existing closed loop receiver to transmitter mechanisms,
`also referred as “RX to TX feedback mechanisms”, that exist
`under IEEE 802.11 include acknowledgement (ACK)frames,
`and transmit power control (TPC) requests and reports. The
`TPC mechanisms mayallow a receiving mobile terminal to
`communicate information to a transmitting mobile terminal
`about the transmit power level that should be used, and the
`link marginat the receiving mobile terminal. The link margin
`may represent the amount of signal power that is being
`received, whichis in excess of a minimum powerrequired by
`the receiving mobile terminal to decode message informa-
`tion, or frames, that it receives.
`A plurality of proposals is emerging for new feedback
`mechanismsas candidates for incorporation in IEEE resolu-
`tion 802.11. Among the proposals for new feedback mecha-
`nismsare proposals from TGn(task group N) syne, whichis
`a multi-industry group that is working to define proposals for
`next generation wireless networks which are to be submitted
`for inclusion in IEEE 802.11, and Qualcomm.The proposals
`may be based upon what may bereferred as a “sounding
`frame”. The sounding frame method may comprisethe trans-
`mitting of a plurality of long training sequences (LTSs) that
`match the number of transmitting antenna at the receiving
`mobile terminal. The sounding frame method maynotutilize
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 14 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 14 of 22
`
`US 7,564,914 B2
`
`5
`beamforming or cyclic delay diversity (CDD). In the sound-
`ing frame method, each antenna may transmit independent
`information.
`
`The receiving mobile terminal may estimate a complete
`reverse channel estimate matrix, H,,,, for the channel defined
`in an uplink direction from the receiving mobile terminal to
`the transmitting mobile terminal. This may require calibra-
`tion with the transmitting mobile terminal where the trans-
`mitting mobile terminal determines the forward channelesti-
`mate matrix, H,,,,,,, for the channel defined in a downlink
`direction from the transmitting mobile terminalto the receiv-
`ing mobile terminal. To compensate for possible differences
`between H,,, and H,,,,,, the receiving mobile terminal may be
`required to receive H,,,,,,, from the transmitting mobile termi-
`nal, and to report H,,,-Hjown a8 feedback information. The
`TGn syne proposal may not currently define a calibration
`response. A channel estimate matrix may utilize 24 or more
`bits for each channel and for each tone, comprising 12 or more
`bits in an in-phase (1) component and 12 or more bits in a
`quadrature (Q) component.
`Accordingto the principle of channelreciprocity, the char-
`acteristics of the RF channel in the direction from the trans-
`mitting mobile terminal to the receiving mobile terminal may
`be the same as the characteristics of the RF channel in the
`
`direction from the receiving mobile terminal to the transmit-
`ting mobile terminal H,,,=H4o.,- In actualpractice, however,
`there may be differences in the electronic circuitry between
`the respective transmitting mobile terminal and receiving
`mobile terminal such that, in some cases, there may not be
`channel reciprocity. This may require that a calibration pro-
`cess be performed in which H,,, and H,,,,,, are comparedto
`reconcile differences between the channel estimate matrices.
`However, there may be limitations inherent in some calibra-
`tion processes. For example, some proposals for new IEEE
`802.11 feedback mechanisms maybe limited to performing
`“diagonal calibrations”. These methods may not be able to
`account for conditions in whichthere are differences in non-
`diagonal coefficients between H,,, and Hd4,.,,. These non-
`diagonalcoefficient differences may bethe result of compli-
`cated antenna couplingsatthe respective transmitting mobile
`terminal and/or receiving mobile terminal. Accordingly, it
`may bevery difficult for a calibration process to correct for
`these couplings. The ability of a calibration technique to
`accurately characterize the RF channel at any instant in time
`may be dependent upona plurality of dynamic factors such
`as, for example, temperature variations. Anotherlimitation of
`calibration proceduresis that it is not known for how long a
`calibration renders an accurate characterization of the RF
`channel. Thus, the required frequency at whichthe calibration
`technique must be performed may not be known.
`Further limitations and disadvantages of conventional and
`traditional approaches will become apparentto one of skill in
`the art,
`through comparison of such systems with some
`aspects ofthe present invention assetforth in the remainder of
`the present application with reference to the drawings.
`
`BRIEF SUMMARY OF THE INVENTION
`
`Certain embodiments of the invention may be found in a
`method and system for MIMO channel measurement
`exchange. Aspects of a method for communicating informa-
`tion in a communication system may comprise transmitting
`data via a plurality of radio frequency (RF) channels utilizing
`a plurality of transmitting antenna, receiving feedback infor-
`mation via at least one of the plurality of RF channels, and
`modifying a transmission mode based on the feedback infor-
`mation. Feedback information may be requested utilizing at
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`least one of the plurality of transmitting antennaviaat least
`one ofthe plurality of RF channels. The numberof transmit-
`ting antenna utilized during the transmitting of data may be
`modified based on the feedback information. The transmis-
`sion characteristics of data transmitted via at least one of the
`
`plurality of transmitting antenna may be modified based on
`the feedback information. Specific feedback information may
`be requested in request messages.
`The method may further comprise negotiating a transmis-
`sion modefor the transmitting of data via at least one of the
`plurality of RF channels. Aspects of the method may further
`comprise receiving feedback information comprising chan-
`nel estimates based on the transmission characteristics of the
`data transmitted by at least oneofthe plurality oftransmitting
`antenna. Feedback information may be derived from math-
`ematical matrix decomposition ofthe channel estimates. Fur-
`thermore, feedback information may be derived from math-
`ematical averaging of the result of mathematical matrix
`decomposition of the channel estimates. Feedback informa-
`tion may also be derived from a calibration of the channel
`estimates for communication in at least one direction via at
`
`least one ofthe plurality of RF channels.
`In another embodimentofthe invention a method for com-
`
`municating information in a communication system may
`comprise receiving data via a plurality of RF channels utiliz-
`ing a plurality of receiving antenna, transmitting feedback
`information via at least one of the plurality of RF channels,
`and requesting modification of the transmission mode for
`received data in transmitted response messages comprising
`the feedback information. Requests for feedback information
`may be received utilizing at least one of the plurality of
`receiving antenna via at least one of the plurality of RF
`channels. There may be requests for modification in the num-
`ber of transmitting antenna utilized during transmission of
`received data in the transmitted response messages compris-
`ing the feedback information. There may be requests for
`modification in the transmission characteristics of data
`received via at least one ofthe plurality of receiving antenna
`in the transmitted response messages comprising the feed-
`back information. The response messages may comprise the
`feedback information requested in the request messages.
`The method may further comprise negotiating the trans-
`mission mode for the data received via at least one of the
`
`plurality of RF channels. Aspects of the method may further
`comprise transmitting feedback information comprising
`channelestimates based on the transmission characteristics of
`the data received via at least one ofthe plurality of receiving
`antenna. Feedback information may be derived from math-
`ematical matrix decomposition ofthe channel estimates. Fur-
`thermore, feedback information may be derived from math-
`ematical averaging of the result of mathematical matrix
`decomposition of the channel estimates. Feedback informa-
`tion may also be derived from a calibration of the channel
`estimates for communication in at least one direction via at
`
`least one ofthe plurality of RF channels.
`Certain aspects of a system for communicating informa-
`tion in a communication system may comprise a transmitter
`that transmits data via a plurality of RF channels utilizing a
`plurality of transmitting antenna, with the transmitter receiv-
`ing feedback informationviaat least one ofthe plurality ofRF
`channels, and with the transmitter modifying a transmission
`mode based on the feedback information. The transmitter
`mayrequest feedback information utilizingat least one ofthe
`plurality of transmitting antennavia at least one ofthe plu-
`rality of RF channels. The numberof transmitting antenna
`utilized during the transmitting of data may be modified
`based on the feedback information. The transmission charac-
`
`

`

`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 15 of 22
`Case 1:23-cv-00633 Document 1-3 Filed 06/02/23 Page 15 of 22
`
`US 7,564,914 B2
`
`7
`teristics of data transmittedvia at least one of the plurality of
`transmitting antenna may be modified based on the feedback
`information. The transmitter may request specific feedback
`information in request messages.
`The system may further comprise the transmitter negotiat-
`ing a transmission modefor the transmitting of data via at
`least one of the plurality of RF channels. Aspects of the
`system may further comprise receiving feedback information
`comprising channel estimates based on the transmission char-
`acteristics of the data transmitted by at least one of the plu-
`rality of transmitting antenna. Feedback information may be
`derived from mathematical matrix decomposition of the
`channel estimates. Furthermore, feedback information may
`be derived from mathematical averaging ofthe result ofmath-
`ematical matrix decomposition of the channel estimates.
`Feedback information mayalso be derived from a calibration
`of the channel estimates for communication in at least one
`
`direction via at least one of the plurality of RF channels.
`These and other advantages, aspects and novel features of
`the present invention, as well as details of an illustrated
`embodimentthereof, will be more fully understood from the
`following description and drawings.
`
`10
`
`15
`
`20
`
`8
`RX/TX feedback mechanisms. In one embodiment of the
`invention, a receiving mobile terminal may periodically
`transmit feedback information, comprising a channel esti-
`mate matrix, H,,,
`to a transmitting mobile terminal. In
`another embodiment of the invention, a receiving mobile
`terminal may perform a singular value decomposition (SVD)
`on the channel estimate matrix, and subsequently transmit
`SVD-derived feedback information to the transmitting
`mobile terminal. Utilizing SVD mayincrease the amount of
`computation required at the receiving mobile terminal but
`