( 12 ) United States Patent
`Li et al .
`
`US 10,965,512 B2
`( 10 ) Patent No .:
`( 45 ) Date of Patent :
`Mar. 30 , 2021
`
`USO10965512B2
`
`( 54 ) METHOD AND APPARATUS USING
`CELL - SPECIFIC AND COMMON PILOT
`SUBCARRIERS IN MULTI - CARRIER , MULTI
`CELL WIRELESS COMMUNICATION
`NETWORKS
`( 71 ) Applicant : Neo Wireless LLC , Wayne , PA ( US )
`( 72 ) Inventors : Xiaodong Li , Kirkland , WA ( US ) ;
`Titus Lo , Bellevue , WA ( US ) ; Kemin
`Li , Bellevue , WA ( US ) ; Haiming
`Huang , Bellevue , WA ( US )
`( 73 ) Assignee : NEO WIRELESS LLC , Wayne , PA
`( US )
`Subject to any disclaimer , the term of this
`patent is extended or adjusted under 35
`U.S.C. 154 ( b ) by 0 days .
`( 21 ) Appl . No .: 17 / 012,813
`Sep. 4 , 2020
`( 22 ) Filed :
`( 65 )
`Prior Publication Data
`Dec. 24 , 2020
`US 2020/0403838 A1
`Related U.S. Application Data
`Continuation of application No. 16 / 440,754 , filed on
`Jun . 13 , 2019 , which is a continuation of application
`( Continued )
`
`( * ) Notice :
`
`( 63 )
`
`( 51 ) Int . Ci .
`H04W 4/00
`H04L 27/26
`
`( 2018.01 )
`( 2006.01 )
`( Continued )
`
`( 52 ) U.S. Cl .
`CPC
`
`H04L 27/2637 ( 2013.01 ) ; H04B 1/707
`( 2013.01 ) ; H04B 770413 ( 2013.01 ) ;
`( Continued )
`( 58 ) Field of Classification Search
`CPC .... H04L 5/0053 ; HO4L 5/0007 ; H04L 5/0048
`See application file for complete search history .
`
`( 56 )
`
`CN
`CN
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5,825,807 A
`5,828,650 A
`
`10/1998 Kumar
`10/1998 Malkamaki et al .
`( Continued )
`FOREIGN PATENT DOCUMENTS
`
`4/2003
`1407745
`10/2003
`1445949
`( Continued )
`
`OTHER PUBLICATIONS
`European Telecommunications Standards Institute , Digital Video
`Broadcasting ( DVB ) ; Framing structure , channel coding and modu
`lation for digital terrestrial television , ETSI EN 300 744 V1.5.1
`( Jun . 2004 ) .
`
`( Continued )
`
`Primary Examiner Omoniyi Obayanju
`( 74 ) Attorney , Agent , or Firm – Volpe Koenig
`
`( 57 )
`ABSTRACT
`Amulti - carrier cellular wireless network ( 400 ) employs base
`stations ( 404 ) that transmit two different groups of pilot
`subcarriers : ( 1 ) cell - specific pilot subcarriers , which are
`used by a receiver to extract information unique to each
`individual cell ( 402 ) , and ( 2 ) common pilots subcarriers ,
`which are designed to possess a set of characteristics com
`mon to all the base stations ( 404 ) of the system . The design
`criteria and transmission formats of the cell - specific and
`common pilot subcarriers are specified to enable a receiver
`to perform different system functions . The methods and
`processes can be extended to other systems , such as those
`with multiple antennas in an individual sector and those
`where some subcarriers bear common network / system infor
`mation .
`
`30 Claims , 13 Drawing Sheets
`
`Subcarrier arrangement for Cello
`
`S
`
`Subcarrier arrangement for Cello
`
`S
`
`C
`
`C
`
`C
`
`C
`
`S
`
`Common pilot
`subcarriers
`
`Cell - specific pilot
`subcarriers
`
`Subcarriers
`for data
`
`Ford Motor Co.
`Exhibit 1001
`Page 001
`
`

`

`US 10,965,512 B2
`Page 2
`
`Related U.S. Application Data
`No. 15 / 688,441 , filed on Aug. 28 , 2017 , now Pat . No.
`10,326,631 , which is a continuation of application
`No. 14 / 746,676 , filed on Jun . 22 , 2015 , now Pat . No.
`9,749,168 , which is a continuation of application No.
`14 / 595,132 , filed on Jan. 12 , 2015 , now Pat . No.
`9,065,614 , which is a continuation of application No.
`13 / 874,278 , filed on Apr. 30 , 2013 , now Pat . No.
`8,934,473 , which is a continuation of application No.
`13 / 212,116 , filed on Aug. 17 , 2011 , now Pat . No.
`8,432,891 , which is a continuation of application No.
`10 / 583,530 , filed as application No. PCT / US2005 /
`001939 on Jan. 20 , 2005 , now Pat . No. 8,009,660 .
`( 60 ) Provisional application No. 60 / 540,032 , filed on Jan.
`29 , 2004 .
`( 51 ) Int . Ci .
`H04W 16/02
`H04B 1/707
`H04L 5/00
`H04L 25/03
`H04L 27/00
`H04W 72/04
`H04B 7/0413
`H04 ) 11/00
`H04L 25/02
`U.S. Ci .
`???
`
`( 2009.01 )
`( 2011.01 )
`( 2006.01 )
`( 2006.01 )
`( 2006.01 )
`( 2009.01 )
`( 2017.01 )
`( 2006.01 )
`( 2006.01 )
`H04J 11/005 ( 2013.01 ) ; H04L 5/0007
`( 2013.01 ) ; H04L 5/0028 ( 2013.01 ) ; H04L
`5/0048 ( 2013.01 ) ; H04L 25/03834 ( 2013.01 ) ;
`H04L 27/0008 ( 2013.01 ) ; H04L 27/0012
`( 2013.01 ) ; H04L 27/2602 ( 2013.01 ) ; H04L
`27/2613 ( 2013.01 ) ; H04L 27/2626 ( 2013.01 ) ;
`H04L 27/2646 ( 2013.01 ) ; H04W 16/02
`( 2013.01 ) ; H04W 72/044 ( 2013.01 ) ; H04W
`72/0446 ( 2013.01 ) ; H04L 5/0016 ( 2013.01 ) ;
`H04L 25/0228 ( 2013.01 ) ; H04L 27/2607
`( 2013.01 ) ; H04L 27/2655 ( 2013.01 ) ; H04L
`27/2657 ( 2013.01 )
`
`( 52 )
`
`( 56 )
`
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`
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`
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`
`1452326
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`
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`
`Ford Motor Co.
`Exhibit 1001
`Page 002
`
`

`

`US 10,965,512 B2
`Page 3
`
`( 56 )
`
`References Cited
`OTHER PUBLICATIONS
`International Search Report and Written Opinion ; International
`Patent Application No. PCT / US05 / 03518 ; Filed Jan. 27 , 2005 ;
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`by Spread Spectrum Pilot Technique , ” Communication Theory
`Mini - Conference , Vancouver , B.C. , Canada , Jun . 6-10 , 1999 , pp .
`115-119 .
`* cited by examiner
`
`Ford Motor Co.
`Exhibit 1001
`Page 003
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 1 of 13
`
`US 10,965,512 B2
`
`104 126
`
`124
`
`122
`
`118
`
`Receiver
`
`Freq . offset comp .
`
`Data
`
`Decodine
`
`uiming est .
`
`ml
`
`EFT
`Free CONAIS
`synch
`
`114
`
`RX
`
`Transmitter
`
`102
`
`112
`
`ais
`
`Data
`108
`
`generation anos
`asertog
`carriers
`Encoding Modulatoa
`
`Data
`
`
`
`
`
`
`
`need pilot Functions that assistance
`
`FIG . 1
`
`Ford Motor Co.
`Exhibit 1001
`Page 004
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 2 of 13
`
`US 10,965,512 B2
`
`200
`
`
`
`S 1 2 3 2 p 3 1 2 1 3 2 1 0 2 1 3 5 3 2 0 3 2 1 3 0 2 1 2 1 3 LEHEHHEHEHE THIL
`
`Channel
`
`
`
`Subcarriers for subchannel 3
`
`3
`
`2
`
`Subcarriers for Subchannel 2
`
`FIG . 2
`
`
`
`Subcarriers for Subchannel 1
`
`
`
`Silent subcarriers
`
`
`
`Pilot subcarriers
`
`Ford Motor Co.
`Exhibit 1001
`Page 005
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 3 of 13
`
`US 10,965,512 B2
`
`300
`
`
`
`Time slots
`
`nt
`
`Entu u
`
`FIG . 3
`
`n of 2
`
`L nghe U
`
`Subchannels
`
`Ford Motor Co.
`Exhibit 1001
`Page 006
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 4 of 13
`
`US 10,965,512 B2
`
`8
`
`402
`
`BS
`
`BS
`
`BS
`
`BS
`
`sa
`
`BS
`
`BS
`
`BS
`
`FIG . 4
`
`BS
`
`BS
`
`BS
`
`BS
`
`Ford Motor Co.
`Exhibit 1001
`Page 007
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 5 of 13
`
`US 10,965,512 B2
`
`C
`
`C
`
`C
`
`C
`
`
`
`Subcarrier arrangement for Cella
`
`
`
`
`
`
`
`
`
`Subcarrier arrangement for Cell p
`
`mu
`
`111
`11111
`
`111
`11111
`
`FIG . 5
`
`data
`
`Cell - specific
`
`Subcarriers for
`pilot subcarriers
`pilot subcarriers
`Common
`
`Ford Motor Co.
`Exhibit 1001
`Page 008
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 6 of 13
`
`US 10,965,512 B2
`
`106
`
`) e **
`4 ( 1 , lema
`
`604
`
`
`
`Electronic memony
`
`12 subcarriers
`
`Pilot subcarrier attributes
`
`602
`
`
`
`Micro processor
`
`FIG . 6
`
`
`
`
`
`Pilot generation and insertion functional block
`
`
`
`
`
`
`
`Ford Motor Co.
`Exhibit 1001
`Page 009
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 7 of 13
`
`US 10,965,512 B2
`
`6 + ( " = ( ) "
`
`0 .- ( 4+ ) = ( x + ) +9
`
`, ( leje : m ( )
`
`?
`
`a inn ( 1x leven ( la )
`
`subcarriers
`
`mm
`
`ki
`
`
`
`) 4 ... ( live allent )
`
`
`
`an tulleita ( 402
`
`FIG . 7
`
`i subcarriers
`
`tk + 1 :
`
`Ford Motor Co.
`Exhibit 1001
`Page 010
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 8 of 13
`
`US 10,965,512 B2
`
`802
`Delay
`
`Transmitter n
`
`www.son In
`Tx ]
`
`FIG . 8
`
`802
`
`Delay Txim
`
`----
`----
`
`m Transmitter m 102
`
`Ford Motor Co.
`Exhibit 1001
`Page 011
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 9 of 13
`
`US 10,965,512 B2
`
`902
`
`Antenna Array LV V V V
`
`*
`
`102
`
`904
`
`906
`
`Branch m
`
`102
`
`Best forming 33 X
`
`XL
`
`sono
`
`23:30
`
`102
`
`forming
`
`X
`
`Pilots 3600
`
`33
`
`EK
`
`asertion
`
`( a )
`
`Branch n
`
`FIG . 9
`
`( b )
`
`Ford Motor Co.
`Exhibit 1001
`Page 012
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 10 of 13
`
`US 10,965,512 B2
`
`MS
`
`
`
`Sector B
`
`1004
`
`Tx
`
`TX
`
`MS
`
`FIG . 10
`
`Sector A
`
`MS
`
`1004
`
`Ford Motor Co.
`Exhibit 1001
`Page 013
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 11 of 13
`
`US 10,965,512 B2
`
`Tx
`
`1102
`
`1108
`
`1106
`
`GPS
`
`MS
`
`Sector B
`
`
`
`Sector A
`
`MS
`
`FIG . 11
`
`MS
`
`1004
`1004
`
`1104
`
`Tx
`
`Ford Motor Co.
`Exhibit 1001
`Page 014
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 12 of 13
`
`US 10,965,512 B2
`
`Group C
`
`Cell B3
`
`Group B
`
`Cell B2
`
`Cell C3
`
`Cell C2
`
`Cell B1
`
`Cell C1
`
`FIG . 12
`
`Cell A3
`
`Cell A2
`
`Cell A1
`
`Group A
`
`Ford Motor Co.
`Exhibit 1001
`Page 015
`
`

`

`U.S. Patent
`
`Mar. 30 , 2021
`
`Sheet 13 of 13
`
`US 10,965,512 B2
`
`Common
`
`
`
`pilot subcarrier Common
`
`
`
`
`
`data subcarrier 10
`
`
`
`Common subcarrier arrangement for Cell p
`
`
`
`Common subcarrier arrangement for Cell a FIG . 13
`
`
`
`
`
`
`
`
`
`data subcarrier Common
`pilot subcarrier Common
`
`
`Ford Motor Co.
`Exhibit 1001
`Page 016
`
`

`

`US 10,965,512 B2
`
`5
`
`10
`
`1
`METHOD AND APPARATUS USING
`CELL - SPECIFIC AND COMMON PILOT
`SUBCARRIERS IN MULTI - CARRIER , MULTI
`CELL WIRELESS COMMUNICATION
`NETWORKS
`
`2
`careful and systematic consideration of the unique require
`ments of the pilot subcarriers .
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG . 1 depicts a basic multi - carrier wireless communica
`tion system consisting of a transmitter and a receiver .
`CROSS - REFERENCE TO RELATED
`FIG . 2 shows basic structure of a multi - carrier signal in
`APPLICATION ( S )
`the frequency domain , which is made up of subcarriers .
`FIG . 3 shows a radio resource divided into small units in
`This application is a continuation of U.S. patent applica
`both the frequency and time domains : subchannels and time
`tion Ser . No. 16 / 440,754 , filed Jun . 13 , 2019 , which is a
`slots .
`continuation of U.S. patent application Ser . No. 15 / 688,441 ,
`FIG . 4 depicts a cellular wireless network comprised of
`filed Aug. 28 , 2017 , which issued as U.S. Pat . No. 10,326 ,
`multiple cells , in each of which coverage is provided by a
`631 on Jun . 18 , 2019 , which is a continuation of U.S. patent 15 base station ( BS ) .
`application Ser . No. 14 / 746,676 , filed Jun . 22 , 2015 , which
`FIG . 5 shows pilot subcarriers divided into two groups :
`issued as U.S. Pat . No. 9,749,168 on Aug. 29 , 2017 , which
`cell - specific pilot subcarriers and common pilot subcarriers .
`is a continuation of U.S. patent application Ser . No. 14/595 ,
`FIG . 6 is an embodiment of pilot - generation - and - insertion
`132 , filed Jan. 12 , 2015 , which issued as U.S. Pat . No.
`functional block shown in FIG . 1 , which employs a micro
`9,065,614 on Jun . 23 , 2015 , which is a continuation of U.S. 20 processor to generate pilot subcarriers and insert them into
`patent application Ser . No. 13 / 874,278 , filed Apr. 30 , 2013 ,
`a frequency sequence contained in the electronic memory .
`which issued as U.S. Pat . No. 8,934,473 on Jan. 13 , 2015 ,
`FIG . 7 shows that common pilot subcarriers are generated
`which is a continuation of U.S. patent application Ser . No.
`by a microprocessor of FIG . 6 to realize phase diversity .
`13 / 212,116 , filed Aug. 17 , 2011 , which issued as U.S. Pat .
`FIG . 8 is an embodiment of delay diversity , which effec
`No. 8,432,891 on Apr. 30 , 2013 , which is a continuation of 25 tively creates phase diversity by adding a random delay time
`U.S. patent application Ser . No. 10 / 583,530 , filed May 30 ,
`duration , either in baseband or RF , to the time - domain
`2007 , which issued as U.S. Pat . No. 8,009,660 on Aug. 30 ,
`signals .
`2011 , which is a U.S. National Stage of PCT Application No.
`FIG . 9 shows two examples for extension to multiple
`PCT / US05 / 01939 , filed Jan. 20 , 2005 , which claims the
`antenna applications .
`benefit of and priority to U.S. Provisional Patent Application 30
`FIG . 10 is an embodiment of synchronization in fre
`No. 60 / 540,032 , filed on Jan. 29 , 2004 , the entire contents of
`quency and time domains of two collocated base stations
`all of which are hereby incorporated by reference herein .
`sharing a common frequency oscillator .
`FIG . 11 is an embodiment of synchronization in fre
`quency and time domains with base stations at different
`BACKGROUND
`35 locations sharing a common frequency reference signal
`generated from the GPS signals .
`In multi - carrier wireless communications , many impor-
`FIG . 12 is an embodiment depicting a wireless network
`tant system functions such as frequency synchronization and
`channel estimation , depicted in FIG . 1 , are facilitated by
`consisting of three groups of cells ( or sectors ) and base
`using the network information provided by a portion of total
`stations in each group that share their own set of common
`subcarriers such as pilot subcarriers . The fidelity level of the 40 pilot subcarriers .
`received subcarriers dictates how well these functions can be
`FIG . 13 shows all base stations within a network transmit ,
`achieved , which in turn affect the efficiency and capacity of
`along with a common pilot subcarrier , a data subcarrier
`carrying data information common to all cells in the net
`the entire network .
`In a wireless network , there are a number of base stations ,
`work .
`each of which provides coverage to designated areas , nor- 45
`mally called a cell . If a cell is divided into sectors , from a
`DETAILED DESCRIPTION
`system engineering point of view each sector can be con
`In the following description the invention is explained
`sidered a cell . In this context , the terms " cell ” and “ sector "
`with respect to some of its various embodiments , providing
`are interchangeable . The network information can be cat-
`egorized into two types : the cell - specific information that is 50 specific details for a thorough understanding and enable
`unique to a particular cell , and the common information that
`ment . However , one skilled in the art will understand that the
`is common to the entire network or to a portion of the entire
`invention may be practiced without such details . In other
`networks such as a group of cells .
`instances , well - known structures and functions have not
`In a multi - cell environment , for example , the base station
`been shown or described in detail to avoid obscuring the
`transmitter of each cell transmits its own pilot subcarriers , in 55 depiction of the embodiments .
`addition to data carriers , to be used by the receivers within
`Unless the context clearly requires otherwise , throughout
`the cell . In such an environment , carrying out the pilot-
`the description and the claims , the words “ comprise , " " com
`dependent functions becomes a challenging task in that , in
`prising , " and the like are to be construed in an inclusive
`addition to the degradation due to multipath propagation
`sense as opposed to an exclusive or exhaustive sense ; that is
`channels , signals originated from the base stations at differ- 60 to say , in the sense of “ including , but not limited to . ” Words
`using the singular or plural number also include the plural or
`ent cells interfere with each other .
`One approach to deal with the interference problem has
`singular number respectively . Additionally , the words
`“ herein , ” “ above , ” “ below ” and words of similar import ,
`been to have each cell transmit a particular pattern of pilot
`subcarriers based on a certain type of cell - dependent random
`when used in this application , shall refer to this application
`process . This approach , to a certain degree , has mitigated the 65 as a whole and not to any particular portions of this
`impact of the mutual interference between the pilot subcar-
`application . When the claims use the word “ or ” in reference
`riers from adjacent cells ; however , it has not provided for a
`to a list of two or more items , that word covers all of the
`
`Ford Motor Co.
`Exhibit 1001
`Page 017
`
`

`

`US 10,965,512 B2
`
`3
`4
`following interpretations of the word : any of the items in the
`the frequency and the time domains . This canonical division
`list , all of the items in the list and any combination of the
`provides a high flexibility and fine granularity for resource
`sharing . The basic structure of a multi - carrier signal in the
`items in the list .
`FIG . 1 depicts a basic multi - carrier wireless communica-
`frequency domain is made up of subcarriers , and within a
`tion system consisting of a transmitter 102 and a receiver 5 particular spectral band or channel there are a fixed number
`104. A functional block 106 at the transmitter , called Pilot
`of subcarriers . There are three types of subcarriers :
`generation and insertion , generates pilot subcarriers and
`1. Data subcarriers , which carry information data ;
`inserts them into predetermined frequency locations . These
`2. Pilot subcarriers , whose phases and amplitudes are
`pilot subcarriers are used by the receiver to carry out certain
`predetermined and made known to all receivers and which
`functions . In aspects of this invention , pilot subcarriers are 10 are used for assisting system functions such as estimation of
`divided into two different groups according to their func-
`system parameters ; and
`tionalities , and hence their distinct requirements . The trans-
`3. Silent subcarriers , which have no energy and are used
`mission format of each group of pilot subcarriers will be
`for guard bands and DC carriers .
`designed so that it optimizes the performance of the system
`The data subcarriers can be arranged into groups called
`functions such as frequency synchronization and channel 15 subchannels to support multiple access and scalability . The
`subcarriers forming one subchannel are not necessarily
`estimation .
`The first group is called “ cell - specific pilot subcarriers , ”
`adjacent to each other . This concept is illustrated in FIG . 2 ,
`showing a basic structure of a multi - carrier signal 200 in the
`and will be used by the receiver 104 to extract information
`unique to each individual cell . For example , these cell-
`frequency domain , which is made up of subcarriers . Data
`specific pilot subcarriers can be used in channel estimation 20 subcarriers can be grouped into subchannels in a particular
`where it is necessary for a particular receiver to be able to
`way . The pilot subcarriers are also distributed over the entire
`differentiate the pilot subcarriers that are intended for its use
`channel in a particular way .
`from those of other cells . For these pilot subcarriers , coun-
`The basic structure of a multi - carrier signal in the time
`domain is made up of time slots to support multiple - access .
`ter - interference methods are necessary .
`The second group is termed “ common pilot sub - carriers , ” 25 The resource division in both the frequency and time
`and are designed to possess a set of characteristics common
`domains is depicted in FIG . 3 which shows a radio resource
`to all base stations of the system . Thus , every receiver 104
`divided into small units in both the frequency and time
`within the system is able to exploit these common pilot
`domains : subchannels and time slots , 300. The basic struc
`subcarriers to perform necessary functions without interfer-
`ture of a multi - carrier signal in the time domain is made up
`ence problem . For instance , these common pilot subcarriers 30 of time slots .
`can be used in the frequency synchronization process , where
`As depicted in FIG . 1 , in a multi - carrier communication
`it is not necessary to discriminate pilot subcarriers of dif-
`system , a generic transmitter may consist of the following
`ferent cells , but it is desirable for the receiver
`combine
`functional blocks :
`coherently the energy of common pilot subcarriers with the
`1. Encoding and modulation 108
`same carrier index from different cells , so as to achieve 35
`2. Pilot generation and insertion 106
`relatively accurate frequency estimation .
`3. Inverse fast Fourier transform ( IFFT ) 110
`Aspects of this invention provide methods to define the
`4. Transmission 112
`transmission formats of the cell - specific and common pilot
`And a generic receiver may consist of the following func
`subcarriers that enable a receiver to perform different system
`tional blocks :
`functions . In particular , a set of design criteria are provided 40
`1. Reception 114
`for pilot subcarriers . Other features of this invention further
`2. Frame synchronization 116
`provide apparatus or means to implement the above design
`3. Frequency and timing compensation 118
`processes and methods . In particular , signal reception can be
`4. Fast Fourier transform ( FFT ) 120
`improved by manipulating phase values of the pilot subcar-
`5. Frequency , timing , and channel estimation 122
`6. Channel compensation 124
`riers and by using power control .
`The methods and processes can also be extended to other
`7. Decoding 126
`cases , such as where multiple antennas are used within an
`Cellular Wireless Networks
`individual sector and where some subcarriers are used to
`In a cellular wireless network , the geographical region to
`carry common network / system information . Base stations
`be serviced by the network is normally divided into smaller
`can be synchronized in frequency and time by sharing a 50 areas called cells . In each cell the coverage is provided by
`common frequency oscillator or a common frequency ref-
`a base station . Thus , this type of structure is normally
`erence signal , such as the one generated from the signals
`referred to as the cellular structure depicted in FIG . 4 , which
`provided by the Global Positioning System ( GPS ) .
`illustrates a cellular wireless network 400 comprised of
`multiple cells 402 , in each of which coverage is provided by
`Multi - Carrier Communication System
`In a multi - carrier communication system such as multi- 55 a base station ( BS ) 404. Mobile stations are distributed
`carrier code division multiple access ( MC - CDMA ) and
`within each coverage area .
`orthogonal frequency division multiple access ( OFDMA ) ,
`A base station 404 is connected to the backbone of the
`information data are multiplexed on subcarriers that are
`network via a dedicated link and also provides radio links to
`mutually orthogonal in the frequency domain . In effect , a
`mobile stations within its coverage . A base station 404 also
`frequency selective channel is broken into a number of 60 serves as a focal point to distribute information to and collect
`parallel but small segments in frequency that can be treated
`information from its mobile stations by radio signals . The
`as flat fading channels and hence can be easily dealt with
`mobile stations within each coverage area are used as the
`using simple one - tap equalizers . The modulation / demodu-
`interface between the users and the network .
`lation can be performed using the fast Fourier transform
`In an M - cell wireless network arrangement , with one - way
`65 or two - way communication and time division or frequency
`( FFT ) .
`In a multi - carrier communication system the physical
`division duplexing , the transmitters at all the cells are
`media resource ( e.g. , radio or cable ) can be divided in both
`synchronized via a particular means and are transmitting
`
`45
`
`Ford Motor Co.
`Exhibit 1001
`Page 018
`
`

`

`US 10,965,512 B2
`
`5
`simultaneously . In a specific cell 402 of this arrangement ,
`the pth cell , a receiver receives a signal at a specific
`subcarrier , the ith subcarrier , at the time tz , which can be
`described as :
`
`6
`To estimate the frequency , normally signals at different
`times are utilized . In an example with two common pilot
`subcarriers of the same frequency index , the received signal
`at time tk + 1 , with respect to the received signal at time tz , is
`5 given by
`
`si ( tk ) = diop ( tik devlei , plk ? +
`
`aimnlti deili mlik )
`
`m = 1
`m # p
`
`( 1 )
`
`10
`
`si ( tk + 1 ) = ed27fia : Xaim ( tk + 1 Dejepi , n6k +1 )
`
`m = 1
`
`( 3 )
`
`and
`
`( 5 )
`
`Pim ( t ) = Pim tk + 1 ) + B ;
`then the frequency can be determined by
`27 / Ar = arg { s / ( k ) , ( k + 1 ) } - B ,
`( 6 )
`where c ; > 0 and --sßist or are predetermined constants for
`all values of m . And from all the frequency estimates { f ; } ,
`a frequency offset can be derived based on a certain crite
`rion .
`For timing estimation , normally multiple common pilot
`carriers are required . In an example of two common pilot
`subcarriers , the received signal at fn , is given by
`
`m = 1
`
`( 9 )
`
`15
`
`20
`
`25
`
`60
`
`si ( t ) = Ž
`di , m ( t ) elli , m ( tk )
`
`m = 1
`
`where At = x + 1 - tz . If At is much less than the coherence
`period of the channel and
`dim ( tx ) = c ; Qim tk + 1 )
`
`( 4 )
`
`where aim ( tx ) and Pim ( tx ) denote the signal amplitude and
`phase , respectively , associated with the ith subcarrier from
`the base station of the min cell .
`Cell - Specific Pilot Subcarriers
`If the ith subcarrier is used as a pilot subcarrier at the pth
`cell for the cell - specific purposes , the cell - specific informa
`tion carried by ai , p ( tx ) and Pip ( tz ) will be of interest to the
`receiver at the pth cell and other signals described by the
`second term on the right hand side of equation ( 1 ) will be
`interference , which is an incoherent sum of signals from
`other cells . In this case , a sufficient level of the carrier - to-
`interference ratio ( CIR ) is required to obtain the estimates of
`airp ( tx ) and ( i , p ( tz ) with desirable accuracy .
`There are many ways to boost the CIR . For examples , the
`amplitude of a pilot subcarrier can be set larger than that of
`a data subcarrier ; power control can be applied to the pilot
`subcarriers ; and cells adjacent to the pth cell may avoid
`using the ith subcarrier as pilot subcarrier . All these can be 30
`achieved with coordination between the cells based on
`certain processes , described below .
`Sn ( tk ) = 2 / 27AFT " * " anmlik lewien , mlk )
`Common Pilot Subcarriers
`The common pilot subcarriers for different cells are
`normally aligned in the frequency index at the time of 35 where Af = f . , - f ; and T , denotes the sampling period . If Af is
`transmission , as depicted in FIG . 5 , which shows pilot
`much less than the coherence bandwidth of the channel and
`subcarriers divided into two groups : cell - specific pilot sub
`carriers and common pilot subcarriers . The cell - specific
`Qi , m ( tx ) = c ( tz ) anm ( tz )
`( 8 )
`pilot subcarriers for different cells are not necessarily
`aligned in frequency . They can be used by the receiver to 40 and
`extract cell - specific information . The common pilot subcar
`Pim ( tz ) = Pnom ( +8 ) + y ( tz )
`riers for different cells may be aligned in frequency , and
`then T , can be determined by
`possess a set of attributes common to all base stations within
`the network . Thus , every receiver within the system is able
`2AAFT ( 1x ) = arg { s ; * { tz ) sqr ( tx ) } - y ( x )
`( 10 )
`to exploit these common pilot subcarriers without interfer- 45
`where c ( tz ) > 0 and -Asy ( t ) st are predetermined constants
`ence problem . The power of the pilot subcarriers can be
`for all values of m .
`varied through a particular power control scheme and based
`on a specific application .
`FIG . 6 is an embodiment of pilot - generation - and - insertion
`functional block 106 shown in FIG . 1 , which employs a
`If the ith subcarrier is used as a pilot subcarrier at the pth
`cell for the common purposes , it is not necessary to consider 50 microprocessor 602 to generate pilot subcarriers and insert
`the second term on the right hand side of equation ( 1 ) to be
`them into a frequency sequence contained in electronic
`interference . Instead , this term can be turned into a coherent
`memory 604. In one embodiment of the invention illustrated
`component of the desirable signal by designing the common
`in FIG . 6 , a microprocessor 602 embedded in the pilot
`pilot carriers to meet the criteria specified in the aspects of
`generation - and - insertion functional block 106 computes the
`this invention , provided that base stations at all cells are 55 attributes of the pilot subcarriers such as their frequency
`synchronized in frequency and time . In such a case the cell
`indices and complex values specified by their requirements ,
`in which the receiver is located becomes irrelevant and ,
`and insert them into the frequency sequence contained in the
`consequently , the received signal can be rewritten as :
`electronic memory 604 , such as a RAM , ready for the
`application of IFFT .
`Diversity for Common Pilot Subcarriers
`Considering equation ( 2 ) , which is the sum of a number
`of complex signals , it is possible for these signals to be
`destructively superimposed on each other and cause the
`The common pilot subcarriers can be used for a number of 65 amplitude of the receiver signal at this particular subcarrier
`to be so small that the signal itself becomes unreliable . Phase
`fu