Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 1 of 22
`
`EXHIBIT E
`
`

`

`US007564914B2
`
`(12) United States Patent
`Hansen et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,564,914 B2
`Jul. 21, 2009
`
`(54)
`
`(75)
`
`(73)
`
`(*)
`
`METHOD AND SYSTEM FOR FRAME
`FORMATS FOR MIMO CHANNEL
`MEASUREMENT EXCHANGE
`
`Inventors: Christopher J. Hansen, Sunnyvale, CA
`(US); Carlos H. Aldana, Mountain
`View, CA (US); Joonsuk Kim, San Jose,
`CA (US)
`Assignee: Broadcom Corporation, Irvine, CA
`(US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 747 days.
`
`Notice:
`
`(21)
`
`Appl. No.: 11/052,353
`
`(22)
`
`Filed:
`
`Feb. 7, 2005
`
`(65)
`
`(60)
`
`(51)
`
`(52)
`(58)
`
`Prior Publication Data
`
`US 2006/O126752 A1
`
`Jun. 15, 2006
`
`Related U.S. Application Data
`Provisional application No. 60/636,255, filed on Dec.
`14, 2004.
`
`Int. C.
`(2006.01)
`H04B 7/02
`(2006.01)
`H04B 7/26
`U.S. Cl. ....................................... 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.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`6,754.475 B1* 6/2004 Harrison et al. .......... 455,115.1
`7,123,887 B2 * 10/2006 Kim et al. ................... 455,103
`2005/0099975 A1
`5/2005 Catreux et al. .............. 370,329
`
`OTHER PUBLICATIONS
`
`Christopher J. Hansen, IEEE 802.11 Wireless LANs WWiSE Pro
`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 exchange is 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 information via at 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
`
`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 2 of 22
`
`Transmitting Mobile feminal
`Sends MIMO Channel Request
`Frame to Receiving Mobile
`Terminal
`
`Receiving Mobile Terminal
`Receives MMO Chafe
`Request frame from
`Transmitting Mobile Terminal
`
`808
`
`Receiving Mobile
`Tennimal Senis Nul
`response?
`
`Yes
`
`808
`
`receiving Mobile Teminal
`Tiarsmits IMO Channel
`response frame to
`Transmitting Mobile Terminal
`Containing MullChannel
`Infortation
`
`
`
`
`
`
`
`80
`
`Receiving Mobile
`Terminal Serids
`Complete Channel
`Response?
`
`receiving Mobile Terminal Transmits
`MIMO Channel Response Frame to
`fransmitting Mobile Terminal
`Containing # of Rows, # of Columns,
`and Complete Channel Estimate Matrix
`Computed During Processing of
`Preamle Field in MMC Channel
`Request frame
`
`814
`
`receiving Mobile
`Terminal Computes
`Complete Channel
`Estinase atrix eased or
`preamble Field in MIMO
`Channel Request Frame
`
`
`
`Receiving Mobile
`Terminal Computes
`Matrix Decomposition on
`Complete Channel
`Estimate Matrix
`
`818
`
`Receiving Mobile Terminal Transmits
`MIMO Channel response Frame to
`transmitting Mobile Terminal
`Containing it of Rows, # of Columns,
`right Singular Wector Matrix, and
`Diagonal Matrix of Singular Walues
`
`

`

`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 1 of 9
`
`US 7,564,914 B2
`
`
`
`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 3 of 22
`
`

`

`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 2 of 9
`
`US 7,564,914 B2
`
`
`
`
`
`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 4 of 22
`
`s
`
`

`

`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 3 of 9
`
`US 7,564,914 B2
`
`3
`
`3
`
`|
`
`s
`
`
`
`S
`
`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 5 of 22
`
`vr
`
`3
`
`

`

`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 4 of 9
`
`US 7,564,914 B2
`
`
`
`s a
`
`H
`O
`.
`
`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 6 of 22
`
`

`

`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 5 Of 9
`
`564,914 B2
`US 7
`
`9
`
`
`
`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 7 of 22
`
`

`

`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 6 of 9
`
`564,914 B2
`US 7
`
`
`
`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 8 of 22
`
`

`

`U.S. Patent
`
`US 7,564,914 B2
`
`
`
`
`
`„In N, = edKL
`
`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 9 of 22
`
`

`

`U.S. Patent
`
`Jul. 21, 2009
`
`Sheet 8 of 9
`
`US 7,564,914 B2
`
`
`
`
`
`
`
`
`
`
`
`ZOZ
`
`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 10 of 22
`
`

`

`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 11 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 makes reference to, claims priority 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.
`
`10
`
`15
`
`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
`MIMO channel measurement exchange.
`
`BACKGROUND OF THE INVENTION
`
`2
`forms of fading is known as multipath fading, in which dis
`persion of transmitted signals due to incident reflections from
`buildings and other obstacles, results in multiple versions of
`the transmitted signals arriving at a receiving mobile termi
`nal. The multiple versions of the transmitted signal may inter
`fere with each other and may result in a reduced signal level
`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 correspond to “dead Zones' in which
`communication to the wireless terminal is temporarily lost.
`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 such that after a symbol is trans
`mitted, a minimum period of time, T, must transpire before
`another symbol may be transmitted. After transmission of a
`symbol from a transmitting mobile terminal, some period of
`dispersion time, T, may transpire which may be 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
`because interference from later arriving 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 symbol from the transmitting mobile terminal while it
`is still receiving the first symbol. This may result in inter
`symbol interference (ISI), producing distortion in received
`signals, and possibility resulting in a loss of information. The
`quantity 1/T is also referred to as the "coherence bandwidth”
`which may indicate 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 may entail utilizing DSP algorithms which perform
`adaptive equalization.
`Another important type of fading is related to motion.
`When a transmitting mobile terminal, or a receiving mobile
`terminal is in motion, the Doppler phenomenon may affect
`the frequency of the received signal. The frequency of the
`received signal may be changed by an amount which is a
`function of the velocity at which a mobile terminal is moving.
`Because of the Doppler effect, ISI may result when a mobile
`terminal is in motion, particularly when the mobile terminal is
`moving at a high velocity. Intuitively, if a receiving mobile
`terminal is in motion and nearing a transmitting mobile ter
`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 transmitter first transmits a signal and when it first 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 power of transmitted signals. If T becomes less than
`T there may be ISI due to the Doppler effect. This case,
`which illustrates 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
`may also be referred to as “frequency selective' fading.
`Smart antenna systems may transmit multiple versions of a
`signal in what is known as “spatial diversity'. A key concept
`in spatial diversity is that the propagation of multiple versions
`of a signal, or “spatial stream’, from different antenna may
`significantly reduce the probability of flat fading at the receiv
`ing mobile terminal since not all of the transmitted signals
`would have the same dead Zone.
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`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 feedback information to a transmitting
`mobile terminal to 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 “beam forming,” which may utilize 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 systems are 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 receiver is receiving
`signals that have been transmitted from a single antenna
`transmitter. With advances in digital signal processing (DSP)
`integrated circuits (ICs) in recent years, multiple antenna
`multiple output (MIMO) systems have emerged in which
`mobile terminals incorporate Smartantenna systems compris
`ing multiple transmit antenna and multiple receive antenna.
`One area of early adoption of MIMO systems has been in the
`field of wireless networking, particularly as applied to wire
`less local area networks (WLANs) where transmitting mobile
`terminals communicate with receiving mobile terminals.
`IEEE resolution 802.11 comprises specifications for commu
`nications between mobile terminals in WLAN systems.
`Signal fading is a significant problem in wireless commu
`65
`nications systems, often leading to temporary loss of commu
`nications at mobile terminals. One of the most pervasive
`
`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 12 of 22
`
`

`

`US 7,564,914 B2
`
`10
`
`15
`
`25
`
`30
`
`35
`
`40
`
`45
`
`3
`Current transmission schemes in MIMO systems typically
`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 decompose a high bit rate data stream into a
`plurality of lowerbitrate data streams such that the aggregate
`bit rates among the plurality of lower bit rate data streams is
`equal to that of the high bit rate data stream. Next, each of the
`lower bit rate data streams may be mapped to 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 may be utilized to form the transmitted “beam in the
`beam forming technique. An example of a data rate maximi
`Zation scheme is orthogonal frequency division multiplexing
`(OFDM), in which each of the plurality of signals is modu
`lated by a different frequency carrier signal prior to mapping
`and multiplicative scaling. OFDM transmission may be resis
`tant to multipath fading in that a portion, but most likely not
`all, of the data transmitted may be 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 received signals. In diversity maxi
`mization, multiple versions of the same signal may be trans
`mitted by a plurality of antenna. The case in which a trans
`mitting mobile terminal is transmitting the same signal via all
`of its transmitting antenna may be the pure spatial diversity
`case in which the aggregate data transfer rate may be equal to
`that of a single antenna mobile terminal. There is a plurality of
`hybrid adaptations of the data rate and spatial diversity maxi
`mization schemes which achieve varying data rates and spa
`tial diversities.
`MIMO systems employing beam forming 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 specificantenna at 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 more efficient uti
`lization of frequency spectrum.
`One of the challenges in beam forming is that the multipli
`cative scale factors which are applied to transmitted and
`received signals may be dependent upon the 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
`60
`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 received signal, y(t), and the
`systems function may be represented as shown in equation
`1:
`
`4
`n(t) represents noise which may be introduced as the signal
`travels through the communications medium and the receiver
`itself. In MIMO systems, 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)
`may be represented 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 be represented by a
`matrix of dimensions NxM. In the case of fast fading, the
`transfer function, H, may itself become 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 MIMO systems 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 preamble field 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 “channel estimates'. For a frequency selec
`tive channel there may be a set of H(t) coefficients for each
`tone that 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 terminal fails to adapt to those changes, infor
`mation loss between the transmitting mobile terminal and the
`receiving mobile terminal may result.
`Higher layer communications protocols, such as the trans
`mission control protocol (TCP) may attempt to adapt to
`detected information losses, but such adaptations may be less
`than optimal and may result 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 MAC layers, 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 computed at 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 may allow a receiving mobile terminal to
`communicate information to a transmitting mobile terminal
`about the transmit power level that should be used, and the
`link margin at the receiving mobile terminal. The link margin
`may represent the amount of signal power that is being
`received, which is in excess of a minimum power required by
`the receiving mobile terminal to decode message informa
`tion, or frames, that it receives.
`A plurality of proposals is emerging for new feedback
`mechanisms as candidates for incorporation in IEEE resolu
`tion 802.11. Among the proposals for new feedback mecha
`nisms are proposals from TGn (task group N) sync, which is
`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 be referred as a “sounding
`frame'. The Sounding frame method may comprise the 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 may not utilize
`
`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 13 of 22
`
`50
`
`55
`
`65
`
`y(t)=Hxx(t)+n(t), where
`
`equation1
`
`

`

`US 7,564,914 B2
`
`10
`
`15
`
`25
`
`30
`
`35
`
`5
`beam forming 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 channel esti
`mate matrix, H: for the channel defined in a downlink
`direction from the transmitting mobile terminal to 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-H, as feedback information. The
`TGn sync proposal may not currently define a calibration
`response. A channel estimate matrix may utilize 24 or more
`bits for eachchannel and for each tone, comprising 12 or more
`bits in an in-phase (I) component and 12 or more bits in a
`quadrature (Q) component.
`According to the principle of channel reciprocity, 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. H. In actual practice, 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 compared to
`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 may be limited to performing
`"diagonal calibrations”. These methods may not be able to
`account for conditions in which there are differences in non
`diagonal coefficients between H and Ha. These non
`diagonal coefficient differences may be the result of compli
`cated antenna couplings at the respective transmitting mobile
`terminal and/or receiving mobile terminal. Accordingly, it
`may be very 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 upon a plurality of dynamic factors such
`45
`as, for example, temperature variations. Another limitation of
`calibration procedures is that it is not known for how long a
`calibration renders an accurate characterization of the RF
`channel. Thus, the required frequency at which the calibration
`technique must be performed may not be known.
`Further limitations and disadvantages of conventional and
`traditional approaches will become apparent to one of skill in
`the art, through comparison of Such systems with some
`aspects of the present invention as set forth in the remainder of
`the present application with reference to the drawings.
`
`6
`least one of the plurality of transmitting antenna via at least
`one of the plurality of RF channels. The number of 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 mode for 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 one of the plurality of transmitting
`antenna. Feedback information may be derived from math
`ematical matrix decomposition of the 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 of the plurality of RF channels.
`In another embodiment of the 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 of the 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
`channel estimates based on the transmission characteristics of
`the data received via at least one of the plurality of receiving
`antenna. Feedback information may be derived from math
`ematical matrix decomposition of the 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 of the 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 information via at least one of the plurality of RF
`channels, and with the transmitter modifying a transmission
`mode based on the feedback information. The transmitter
`may request feedback information utilizing at least one of the
`plurality of transmitting antenna via at least one of the plu
`rality of RF channels. The number of transmitting antenna
`utilized during the transmitting of data may be modified
`based on the feedback information. The transmission charac
`
`40
`
`50
`
`55
`
`Case 1:22-cv-22706-RNS Document 1-22 Entered on FLSD Docket 08/25/2022 Page 14 of 22
`
`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
`
`60
`
`65
`
`

`

`US 7,564,914 B2
`
`7
`teristics of data transmitted via 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 mode for 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 of the result of math
`ematical matrix decomposition of the channel estimates.
`Feedback information may also 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
`embodiment thereof, will be more fully understood from the
`following description and drawings.
`
`10
`
`15
`
`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 may increase the amount of
`computation required at the receiving mobile terminal but
`may reduce the quantity of information which is transmitted
`to the transmitting mobile terminal via the RF channel in
`comparison to transmitting the entire channel estimate
`matrix. Yet another embodiment of the invention may expand
`upon the method utilizing Sounding frames to incorporate
`calibration. In this aspect of the invention, a receiving mobile
`terminal, after transmitting a Sounding frame, may Subse
`quently receive a channel estimate matrix, H, from the
`transmitting mobile terminal. The receiving mobile terminal
`may then transmit feedback information which is based upon
`the difference H-H to the transmitting mobile termi
`dova
`nal.
`One embodiment of the invention may comprise a MIMO
`channel probe and response method, which may provide a
`flexible solution for RX/TX feedback because it may support
`a plurality of feedback mechanisms. In this regard, a trans
`mitting mobile terminal may query a receiving mobile termi
`nal to provide feedback information about the transmit mode
`configuration to use. The transmitting mobile terminal may
`receive feedback information comprising a full channel esti
`mate matrix as computed by a receiving mobile terminal.
`Alternatively, the transmitting mobile terminal may receive
`feedback information comprising decomposition matrices
`that were derived from a full channel estimate matrix, or the
`transmitting mobile terminal may receive feedback informa
`tion comprising matrices which contain averaged values
`derived from the decomposition matrices. Furthermore, the
`transmitting mobile terminal may receive feedback informa
`tion which may be utilized in a calibration procedure.
`RX/TX feedback mechanisms may be required to achieve
`high information transfer rates even in fast fading RF chan
`nels. In fast fading RF channels, however, the channel esti
`mate matrix H(t) may change rapidly. Thus, the amount of
`feedback information that is required may also increase.
`Transmission of a large quantity of RT/TX feedback infor
`mation may create excessive overhead on the RF channel and
`may reduce the available rate at which other information
`transfer may occur via the RF channel.
`SVD is a method which may reduce the quantity of channel
`feedback informatio