(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2003/0174048A1
`(43) Pub. Date:
`Sep. 18, 2003
`McCorkle
`
`US 2003O174048A1
`
`(54) METHOD AND SYSTEM FOR PERFORMING
`DISTANCE MEASURING AND DIRECTION
`FINDING USING ULTRAWIDE BANDWDTH
`TRANSMISSIONS
`(76) Inventor: John W. McCorkle, Vienna, VA (US)
`Correspondence Address:
`XTREMESPECTRUM, INC.
`8133 LESSBURG PIKE
`SUTE 700
`VIENNA, VA 22182 (US)
`(21) Appl. No.:
`10/318,371
`(22) Filed:
`Dec. 13, 2002
`Related U.S. Application Data
`(63) Continuation-in-part of application No. 09/209,460,
`filed on Dec. 11, 1998.
`Continuation-in-part of application No. 09/685,202,
`filed on Oct. 10, 2000.
`Continuation-in-part of application No. 10/214,183,
`filed on Aug. 8, 2002.
`
`(60) Provisional application No. 60/339,372, filed on Dec.
`13, 2001.
`
`Publication Classification
`
`(51) Int. Cl." ....................................................... H04Q 5/22
`(52) U.S. Cl. ......................................... 340/10.34; 375/130
`
`(57)
`
`ABSTRACT
`
`An identification tag is provided in which radio frequency
`(RF) circuitry and ultrawide bandwidth (UWB) circuitry are
`both provided on the same tag, along with some UWB-RF
`interface circuitry. The RF circuitry is used to detect when
`the identification tag must be accessed, and is used to
`connect the UWB circuitry with a power Supply. The UWB
`circuitry then performs the necessary communication func
`tions with a distant device and the power Supply is again
`disconnected. In this way the power Supply is only accessed
`when the UWB circuitry is needed and its usable lifetime
`can be maximized.
`
`A.
`w\
`105
`
`110
`
`100
`\A
`
`120
`Af f\
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`122
`! /V
`
`124
`f
`/V
`
`130
`
`one" - - - - - -
`igita
`g
`132
`//
`
`Receiver
`Front End
`
`Demodulator
`
`Receiver
`Baseband
`
`
`
`//
`
`140
`\
`^
`
`s
`
`150
`%
`
`|
`l
`:
`I
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`
`A
`
`128
`
`!
`
`:
`Timing
`- Controller
`;:
`:
`
`
`
`
`
`Transmitter
`Front End
`
`Modulator
`
`:
`
`!
`
`Transmitter
`Baseband
`
`--mo
`
`136
`
`134
`-2/
`
`PHY Layer
`Conversion
`Protocol
`
`Media
`Access
`H
`Controller -->
`Controller
`
`(PLCP)
`
`(MAC)
`
`:
`
`|
`
`----------------------------------------------------
`
`MAC
`Management
`
`70
`
`
`
`
`
`
`
`PHY Layer
`Manager
`
`
`
`175
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`Patent Application Publication
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`Sep. 18, 2003 Sheet 1 of 22
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`US 2003/0174048A1
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`06 I
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`
`
`
`
`(OVW)(JOTH)
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`
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`pUIE QUOJA
`
`SLI
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`Patent Application Publication Sep. 18, 2003 Sheet 2 of 22
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`US 2003/0174048A1
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`ZZI
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`Patent Application Publication Sep. 18, 2003 Sheet 3 of 22
`
`US 2003/0174048A1
`
`11
`
`input
`Devices
`
`
`
`315
`
`317
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`
`
`319
`
`Al
`321
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`Processor
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`Patent Application Publication Sep. 18, 2003 Sheet 4 of 22
`
`US 2003/0174048A1
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`400
`
`V\
`
`105
`
`W\
`
`Remote Device
`
`
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`Remote Device 2
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`Patent Application Publication Sep. 18, 2003 Sheet 5 of 22
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`US 2003/0174048A1
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`
`
`
`
`
`
`
`
`
`
`
`
`Local Device Establishes a Unique Link with
`Remotic Access Devices. Using a Multiple
`Access Protocol (See Fig. 6)
`
`Local Device Determines Distance to Each
`Linked Remote Device (Sec Fig. 7)
`
`Local Device Communicates with Each Linked
`Remote Device Based on Determined Distances
`(See Figs. 8 and 10-12)
`
`Local Device Updates Links with Remote
`Devices (See Fig.9)
`
`
`
`503
`
`505
`
`509
`
`Fig. 5
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`Patent Application Publication Sep. 18, 2003 Sheet 6 of 22
`
`US 2003/0174048A1
`
`START
`
`Transmit Join Message from Local Device to Unlinked
`Remote Device
`
`Receive Join Message in Unlinked Remote Devices
`and Synchronize with Local Device
`
`In Each Unlinked Remote Device, Encode a Unique
`Identifier and Transmit as a Reply to Local Device
`
`Receive Each Reply in Local Device and Synchronize
`with Each Unlinked Remote Device
`
`601
`
`603
`
`605
`
`607
`
`511
`
`
`
`
`
`
`
`Decode Each Unique Identifier in Local Device and
`Establish a Unique Communications Link with Each
`Remote Device Based on the Unique Identifiers
`
`609
`
`Fig. 6
`
`END
`
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`Patent Application Publication Sep. 18, 2003 Sheet 7 of 22
`
`US 2003/0174048A1
`
`507
`
`Transmit distance-determining message from local device to each linked
`remote device via unique links
`
`701
`
`
`
`
`
`
`
`Mark transmitting time for transmission on each unique link as 1,
`
`Receive distance-determining message in each linked remote device and
`transmit a response from each remote device via respective unique links
`
`Receive cach response in local device via respective unique links
`
`Mark receiving time for each reception on each unique link as 1,
`
`Determine processing delay for each linked remote device as d
`
`Compute round trip time T for each linked remote device
`T - t, -t, -d
`
`Compute distance D to each linked remote device
`D = Cx T/2
`
`705
`
`707
`
`709
`
`713
`
`715
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`Patent Application Publication Sep. 18, 2003 Sheet 8 of 22
`
`US 2003/0174048A1
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`Obtain range criteria r of local device
`
`801
`
`
`
`Compare range criteriar with determined distance D of each linked 12- 803
`remote device
`
`809
`
`Enable communications with in-range
`devices
`
`Block communications with out of range
`devices
`
`
`
`811 NSN Update distance information for cnabled
`links
`
`Update distance information for block
`links
`
`507 sys
`
`communication
`
`no communication
`
`Fig. 8
`
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`Patent Application Publication Sep. 18, 2003 Sheet 9 of 22
`
`US 2003/0174048A1
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`
`
`901
`
`903
`
`905
`
`Determine if remote devices have exited
`wireless network
`
`Update network count of remote devices
`in wireless network
`
`Determine if new remote devices have
`entered wireless network
`
`907
`
`Maximum capacity?
`
`Update network count of remote devices
`in wireless network
`
`Fig. 9
`
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`Patent Application Publication Sep. 18, 2003 Sheet 10 of 22 US 2003/0174048A1
`
`Obtain Authentication Range a
`Of Device
`
`Compare Authentication Range a with
`a Determined Distance D of Each
`Linked Remote Device (D <- a)
`
`O3
`10
`
`
`
`
`
`
`
`
`
`
`
`Authentication?
`
`1 / 1007
`Block Communications
`with Non-Authenticated K
`Devices
`
`1011
`WN Enable Communications
`with Authenticated Devices
`
`
`
`Update Distance
`p
`Information for Non
`Authenticated Devices
`
`1009
`2/
`
`No Communication
`
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`

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`Patent Application Publication Sep. 18, 2003 Sheet 11 of 22
`
`US 2003/0174048A1
`
`N
`
`
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`Patent Application Publication Sep. 18, 2003 Sheet 12 of 22
`
`US 2003/0174048A1
`
`X
`
`-
`
`-
`
`Transmit a position-determining message from local device to each
`linked remote device via respective links
`
`r
`
`12.01
`
`/
`
`1203
`
`1205
`1
`l/
`
`1207
`
`1209
`
`o
`Receive position-determining message in each linked remote device
`and transmit an answer including position data from each linked
`remote device via respective unique links
`
`Receive each answer in local device via respective unique links
`
`
`
`Determine position of each linked remote device by triangulation
`and display remote devices on local display
`
`Determine communications based on uscr sclection of positions
`
`selected
`
`unselected
`
`1215
`
`
`
`Enable data communications
`within selected devices
`
`Block data communications with
`unselected devices
`
`1211
`
`1217
`NSN Update position information for
`enabled links
`
`
`
`Update position information for
`block links
`
`1213
`
`communications S's 507
`
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`

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`Patent Application Publication Sep. 18, 2003 Sheet 13 of 22
`
`US 2003/0174048A1
`
`Transmit Request For Secured Communications
`Including Public Key From Local Device To
`Enabled Remote Devices
`
`1301
`
`Receive Public Key And Request For Secured
`Communications in Enabled Remote Devices
`
`1303
`
`Encrypt Data Using Public Key And Algorithm
`And Transmit Encrypted Data From Each Enabled
`Remote Device
`
`Receive Encrypted Data In Local Device
`
`
`
`
`
`Obtain Private Key And Decrypt Data Using Same
`Algorithm. As In Step 1305
`
`1309
`
`Fig. 13
`
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`Patent Application Publication Sep. 18, 2003 Sheet 14 of 22 US 2003/0174048A1
`
`
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`Patent Application Publication Sep. 18, 2003 Sheet 15 of 22 US 2003/0174048A1
`
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`Patent Application Publication Sep. 18, 2003 Sheet 16 of 22
`
`US 2003/0174048A1
`
`SZ91
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`| 079 I
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`DVW
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`[000101&II 19I
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`Patent Application Publication Sep. 18, 2003 Sheet 17 of 22
`
`US 2003/0174048A1
`
`
`
`
`
`RF Circuitry
`
`1810
`
`
`
`T 1820
`
`UWB Circuitry
`
`1805
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`Patent Application Publication Sep. 18, 2003 Sheet 18 of 22 US 2003/0174048A1
`
`Combined UWB-RFID Tag
`f O
`
`
`
`RF Circuitry
`
`1900
`
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`Patent Application Publication Sep. 18, 2003 Sheet 19 of 22 US 2003/0174048A1
`
`Combined UWB-RFID Tag
`
`r wr- r rr H wr H wr - - - - -
`
`UWB-RF Interface
`
`2140
`
`
`
`2100 SS
`
`WA
`2120
`
`2105
`
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`Patent Application Publication Sep. 18, 2003 Sheet 20 of 22 US 2003/0174048A1
`
`RF Cicruitry
`
`
`
`2200
`
`Combined UWB-RFID Tag
`
`UWB-RF Interface
`
`2235
`
`224)
`
`224.5
`
`
`
`UWB Circuitry
`
`|
`
`2220
`
`2205
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`Patent Application Publication Sep. 18, 2003 Sheet 21 of 22
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`US 2003/0174048A1
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`Patent Application Publication Sep. 18, 2003 Sheet 22 of 22
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`US 2003/0174048A1
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`US 2003/0174048A1
`
`Sep. 18, 2003
`
`METHOD AND SYSTEM FOR PERFORMING
`DISTANCE MEASURING AND DIRECTION
`FINDING USING ULTRAWIDE BANDWDTH
`TRANSMISSIONS
`
`CROSS-REFERENCE TO RELATED PATENT
`DOCUMENTS
`0001. This application is a continuation-in-part of U.S.
`application Ser. Nos. 09/209,460, for “ULTRA WIDE
`BANDWIDTH SPREAD-SPECTRUM COMMUNICA
`TION, filed Dec. 11, 1998; 09/685,202, for “METHOD
`AND SYSTEM FOR ENABLING DEVICE FUNCTIONS
`BASED ON DISTANCE INFORMATION,” filed Oct. 10,
`2000; and 10/214,183, for “MODE CONTROLLER FOR
`SIGNAL ACOUISITION AND TRACKING IN AN
`ULTRAWIDEBAND COMMUNICATIONSYSTEM, filed
`Aug. 8, 2002, all of which are incorporated by reference in
`their entirety. This application relies for priority on U.S.
`provisional application No. 60/339,372, for “METHOD
`AND SYSTEM FOR PERFORMING DISTANCE MEA
`SURING AND DIRECTION FINDING USING ULTRA
`WIDE BANDWIDTH TRANSMISSIONS, filed Dec. 13,
`2001, which is incorporated by reference in its entirety.
`
`BACKGROUND OF THE INVENTION
`0002 The present invention relates to radio frequency
`(RF) communication receivers, Systems and methods
`employing ultra wide bandwidth (UWB) signaling tech
`niques. More particularly, the present invention relates to the
`Systems and methods that use UWB transmissions to track
`the movement of remote devices by determining those
`devices movement, direction, and distance with respect to
`a central device. Even more particularly, the present inven
`tion relates to systems and methods that use both RF
`transmissions and UWB transmissions in the same device.
`0003. It is desirable in many environments to be able to
`monitor the location or movement of a remote device from
`a fixed local device. For example, retail Stores may wish to
`monitor their merchandise; warehouses or cargo transports
`may wish to keep closer track of the cargo that they handle;
`and internal communications networks may wish to keep
`track of what users are in which location. Thus, a variety of
`devices have been used to determine location and distance.
`0004. An example of such a device is an RF identity tag,
`e.g., as described in U.S. Pat. No. 5,995,006, to Walsh, U.S.
`Pat. No. 6,107,910, to Nysen, or devices of a similar design.
`Such an RF identity tag has RF circuitry that can detect RF
`Signals transmitted by a local device (whether fixed or
`mobile) and can then reply with an RF signal of its own to
`send information back to the local device. The RF signal in
`this case is a data Signal modulated by being impressed upon
`another RF carrier Signal.
`0005 The present inventors have also presented a system
`and method for using UWB signals to achieve similar
`functions, as set forth in U.S. Pat. No. 09/685,202, for
`“METHOD AND SYSTEM FOR ENABLING DEVICE
`FUNCTIONS BASED ON DISTANCE INFORMATION,"
`filed Oct. 10, 2000. The UWB signal in this case is prefer
`ably one that approximately matches its bandwidth to its
`center frequency, as defined below.
`0006. One important aspect of remote devices such as
`these is their useful lifetime. If a receiver is used in a remote
`
`device, the device may have a limited power Supply, e.g., a
`battery. In this case, it is desirable to minimize the use of the
`power Source So as to extend its usable lifetime.
`0007 Some RF tags operate without a separate power
`Supply. Instead they use the RF signal they receive to power
`themselves up and perform their desired function, e.g.,
`having the incoming RF signal charge a capacitor. This is not
`possible with current UWB designs. While UWB transceiv
`erS may use low amounts of power they cannot use a power
`Source capacitively charged by an incoming RF signal.
`However, the UWB tags proposed by the current inventors
`offer better reliability in cluttered environment, as well as
`other Significant advantages.
`0008. It would therefore be desirable to provide a system
`that includes the advantages of both designs, while limiting
`their limitations.
`
`SUMMARY OF THE INVENTION
`0009 Consistent with the title of this section, only a brief
`description of Selected features of the present invention is
`now presented. A more complete description of the present
`invention is the Subject of this entire document.
`0010. An object of the present invention is to provide a
`remote device that can receive information from a local
`device and perform a desired function in response, e.g.,
`Sending a return signal with a maximum reliability and a
`minimum use of power.
`0011) Another object of the present invention is to maxi
`mize the coordination of RF and UWB elements used in a
`Single remote device.
`0012 Another feature of the present invention is to
`address the above-identified and other deficiencies of con
`ventional communications Systems and methods.
`0013 These and other objects are accomplished by way
`of a remote device configured to receive both RF and UWB
`transmissions. While several embodiments are disclosed
`herein, one embodiment would be to include RF circuitry to
`receive an RF signal, UWB circuitry to transmit a UWB
`signal, and a UWB-RF interface to facilitate communication
`between these two elements.
`0014.
`In an effort to achieve these goals a combined
`ultrawide bandwidth-radio frequency (UWB-RF) remote
`identification tag is provided, which comprises: ultrawide
`bandwidth (UWB) circuitry for receiving or transmitting
`UWB signals; radio frequency (RF) circuitry for receiving
`or transmitting RF signals, and interface circuitry formed
`between the RF circuitry and the UWB circuitry.
`0.015 This combined UWB-RF remote identification tag
`may further comprise: a power Supply for providing power
`to the UWB circuitry; and a Switch connected between the
`power supply and the UWB circuitry. The interface circuitry
`preferably controls the operation of the Switch based on a
`signal received from the RF circuitry.
`0016. The UWB-RF interface may further comprise a
`first Scaler for receiving a frequency Signal from the RF
`circuitry, Scaling it by a first Scaling factor N/M, and
`providing a first scaled frequency to the UWB circuitry. In
`this case N and M are preferably integers.
`
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`US 2003/0174048A1
`
`Sep. 18, 2003
`
`0017. The combined UWB-RF remote identification tag
`may further comprise: a power Supply for providing power
`to the UWB circuitry; and a Switch connected between the
`power supply and the UWB circuitry. The interface circuitry
`preferably controls the operation of the Switch based on a
`Signal received from the RF circuitry. The Scaled frequency
`is preferably used by the UWB circuitry as a pulse repetition
`frequency.
`0018. The UWB-RF interface may further comprise: a
`Second Scaler for receiving the frequency Signal from the RF
`circuitry, Scaling it by a Second Scaling factor P/O, and
`providing a Second Scaled frequency to the UWB circuitry;
`a memory device for providing a data Signal, and a mixer for
`mixing the Second Scaled frequency with the data Signal to
`form a UWB radio frequency signal. In this design P and Q
`are preferably integers.
`0019. The UWB-RF interface may further comprise all
`of a first Scaler for receiving a frequency Signal from the RF
`circuitry, Scaling it by a first Scaling factor N/M, and
`providing a first scaled frequency to the UWB circuitry; a
`Second Scaler for receiving the frequency Signal from the RF
`circuitry, Scaling it by a Second Scaling factor P/O, and
`providing a Second Scaled frequency to the UWB circuitry;
`a memory device for providing a data Signal, and a mixer for
`mixing the Second Scaled frequency with the data Signal to
`form a UWB radio frequency Signal, and providing the
`UWB radio frequency signal to the UWB circuitry. In this
`design N, M, P and Q are all preferably integers.
`BRIEF DESCRIPTION OF THE DRAWINGS
`0020. A more complete appreciation of the invention and
`its many attendant advantages will be readily obtained as it
`becomes better understood with reference to the following
`detailed description when considered in connection with the
`accompanying drawings, in which:
`0021
`FIG. 1 is a block diagram of an ultra-wide band
`(UWB) system according to a preferred embodiment of the
`present invention;
`0022 FIG. 2 is a block diagram of an ultra-wide band
`(UWB) transceiver according to a preferred embodiment of
`the present invention;
`0023 FIG. 3 illustrates a processor system according to
`a preferred embodiment of the present invention;
`0024 FIG. 4 is a diagram depicting the interconnection
`of devices according to a preferred embodiment of the
`present invention;
`0025 FIG. 5 is a flow chart describing a process for
`communicating with remote wireleSS devices based on dis
`tance information according to a preferred embodiment of
`the present invention;
`0.026
`FIG. 6 is a flow chart describing the process of
`establishing a link with remote devices using a multiple
`access protocol according to a preferred embodiment of the
`present invention;
`0027 FIG. 7 is a flow chart describing the process of
`determining distance to a remote device according to a
`preferred embodiment of the present invention;
`0028 FIGS. 8 and 9 describe alternative processes for
`communicating with remote devices based on distance infor
`mation in accordance with other preferred embodiments of
`the present invention;
`
`0029 FIGS. 10 and 11 describe an alternative process
`for communicating with remote devices based on distance
`information in accordance with other preferred embodi
`ments of the present invention;
`0030 FIG. 12 describes a process for providing secured
`communications with remote devices according to a pre
`ferred embodiment of the present invention;
`0031
`FIG. 13 is a flow chart that describes an exemplary
`process for providing a Secured communications link using
`public key cryptography in accordance with a preferred
`embodiment of the present invention;
`0032 FIG. 14 is a block diagram of a remote device
`according to a preferred embodiment of the present inven
`tion;
`0033 FIG. 15 is a block diagram of a remote device
`according to another preferred embodiment of the present
`invention;
`0034 FIG. 16 is a block diagram of a remote device
`according to yet another preferred embodiment of the
`present invention;
`0035 FIG. 17 is a block diagram showing a combined
`UWB-RF tag according to a first preferred embodiment;
`0036 FIG. 18 is a block diagram showing a combined
`UWB-RF tag according to a second preferred embodiment;
`0037 FIG. 19 is a block diagram showing a combined
`UWB-RF tag according to a third preferred embodiment;
`0038 FIG. 20 is a block diagram showing a combined
`UWB-RF tag according to a fourth preferred embodiment;
`0039 FIG. 21 is a block diagram showing a combined
`UWB-RF tag according to a fifth preferred embodiment;
`0040 FIG. 22 is a block diagram showing a combined
`UWB-RF tag according to a sixth preferred embodiment;
`0041
`FIGS. 23A to 23C are signal graphs showing an
`embodiment in which pulse position modulation (PPM) is
`used to make a UWB signal coherent with an RF signal; and
`0042 FIGS. 24A to 24C are signal graphs showing an
`embodiment in which bi-phase modulation is used to make
`a UWB signal coherent with an RF signal.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`0043 Preferred embodiments of the present invention
`will now be described with reference to the drawings.
`Throughout the Several views, like reference numerals des
`ignate identical or corresponding parts.
`0044 FIG. 1 is a block diagram of an ultra-wide band
`(UWB) system according to a preferred embodiment of the
`present invention. As shown in FIG.1, the UWB system 100
`includes an antenna 105, a Switch 110, an RF physical
`medium device (PMD) 120, a digital PMD 130, a physical
`(PHY) layer conversion protocol (PLCP) 140, a media
`access controller (MAC) 150, a host controller 160, a MAC
`manager 170, a PHY layer manager 175, and an electronic
`device 180. The RF PMD 120 further includes a receiver
`front end 122, a demodulator 124, a transmitter front end
`126, and a modulator 128, while the digital PMD 130 further
`includes a receiver baseband 132, a transmitter baseband
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`134, and a timing controller 136. The device 180 may
`include an application layer 185 that allows the device to
`operate in connection with the host controller 160 and a user
`190.
`0.045 Although a single antenna 105 is shown that
`Switches between transmitting and receiving, individual
`receiving and transmitting antennas may be used in alternate
`embodiments.
`0046) When the UWB system 100 is receiving a signal,
`the antenna 105 converts an incoming UWB electromag
`netic waveform into an electrical signal (or optical signal)
`and provides this signal to the Switch 110. In a receiving
`mode the Switch 110 is connected to the receiver front end
`122 in the RF PMD 120, which performs analog signal
`processing on the incoming Signal. Depending on the type of
`waveform, the receiver front end 122 processes the electrical
`(or optical) signals So that the level of the signal and spectral
`components of the Signal are Suitable for processing in the
`demodulator 124. This processing may include spectral
`Shaping, Such as a matched filtering, partially matched
`filtering, Simple roll-off, etc.
`0047 The received signal is then passed from the
`receiver front end 122 through the demodulator 124 and the
`receiver baseband 132 for Signal processing to extract the
`information from the incoming Signal. The demodulator 124
`performs analog Signal processing on the incoming RF
`signal, which is then converted (preferably by either the
`demodulator 124 or the receiver baseband 132) for digital
`processing by the receiver baseband 132.
`0.048. The information extracted from the incoming sig
`nal is then sent from the receiver baseband 132 to the PLCP
`140 to convert it to proper format for the MAC 150. Timing
`information from the incoming Signal (or from a signal
`output from the demodulator 124) is received by the timing
`controller 136 and is Sent back to timing generators in the
`demodulator 124 and the modulator 128. (See FIG. 2 and
`related discussion.)
`0049. The MAC 150 serves as an interface between the
`UWB wireless communication functions implemented by
`both the RF PMD 120 and the digital PMD and the appli
`cation layer 185 that uses the UWB communications chan
`nel for exchanging data with the device 180. The MAC 150
`is preferably a processor-based unit that is implemented
`either with hard-wired logic, Such as in one or more appli
`cation specific integrated circuits (ASICs) or in one or more
`programmable processors.
`0050. The host controller 160 operates as an interface
`between the MAC 150 and the device 180, and provides
`instructions to the RF PMD 120, the digital PMD 130, the
`PLCP 140 and the MAC 150 through the MAC manager 170
`and the PHY layer manager 175. In this embodiment the host
`controller 160 is shown as being separate from the device
`180. In alternate embodiments all or part of the host con
`troller 160 can be placed in the device 180.
`0051 FIG. 2 is a more detailed block diagram of the
`UWB transceiver of FIG.1. As shown in FIG. 2, the UWB
`transceiver includes an antenna 105, a transmit/receive
`(T/R) switch 110, a receiver front end 122, a transmitter
`front end 126, a demodulator 124, a modulator 128, and a
`digital PMD 130. The demodulator 124 includes a splitter
`210, a plurality of correlators 220-220, and a plurality of
`
`input timing generators 825-825. The modulator 128
`includes an output timing generator 205, an encoder 225,
`and a waveform generator 230. In this embodiment the
`output timing generator 205 and the plurality of input
`timing generators 205-205 are formed together into a
`single timing generator module 205. This embodiment
`allows multiple fingers (also called arms) to process the
`incoming Signal at the same time, increasing the Speed and
`efficiency of acquisition and tracking.
`0.052 The T/R switch 110 connects the antenna 105 to
`either the receiver front end 122, or the transmitter front end
`126, depending upon whether the transceiver is transmitting
`or receiving. In alternate embodiments Separate transmitting
`and receiving antennas could be used.
`0053 When receiving energy through the antenna 105,
`the received energy is coupled in to the T/R Switch 110,
`which passes the energy to the receiver front end 122 as an
`incoming Signal. The receiver front end 122 filters, extracts
`noise, and adjusts the amplitude of the incoming Signal
`before providing the same to the splitter 210 in the demodu
`lator 124.
`0054 The splitter 210 divides the incoming signal up into
`N copies of the incoming Signal and applies the N incoming
`Signals to respective correlatorS 220-220. Each of the
`correlatorS 220-220 receives a clock input Signal from a
`respective input timing generator 205-205 of the timing
`generator module 205 as shown in FIG. 2. Each of these
`correlators corresponds to a different finger of the trans
`ceiver.
`0055 The input timing generators 205-205 receive a
`phase and frequency adjustment signal from the digital PMD
`130, but may also receive a fast modulation signal or other
`control signals as well. The digital PMD 130 may also
`provide control signals (e.g., phase, frequency and fast
`modulation signals, etc.) to the timing generator module 205
`for time Synchronization and modulation control. The fast
`modulation control Signal may be used to implement, for
`example, chirp waveforms, PPM waveforms, such as fast
`time scale PPM waveforms, etc.
`0056. The digital PMD 130 may also provide control
`Signals to, for example, the encoder 225, the waveform
`generator 230, and the transmitter front end 126, the T/R
`Switch 110, the receiver front end 122, the correlators
`220-220, etc., for controlling, for example, amplifier
`gains, Signal waveforms, filter passbands and notch func
`tions, alternative demodulation and detecting processes, user
`codes, Spreading codes, cover codes, etc.
`0057. During signal acquisition, the digital PMD 130
`adjusts the phase input of the first input timing generator
`205, in an attempt for the first tracking correlator 220 to
`identify and the match the timing of the Signal produced at
`the receiver with the timing of the arriving signal. When the
`received signal and the locally-generated Signal coincide in
`time with one another, the digital PMD 130 senses the high
`Signal Strength or high SNR and begins to track, indicating
`that the receiver is Synchronized with the received signal.
`0058. Once synchronized, the receiver will operate in a
`track mode, where the first input timing generator 205 is
`adjusted by way of a continuing Series of phase adjustments
`to counteract any differences in timing of the first input
`timing generator 205 and the incoming Signal. However, a
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`feature of the present invention is that by Sensing the mean
`of the phase adjustments over a known period of time, the
`digital PMD 130 adjusts the frequency of the first input
`timing generator 205 So that the mean of the phase adjust
`ments becomes Zero.
`0059. The frequency is adjusted in this instance because
`it is clear from the pattern of phase adjustments that there is
`a frequency offset between the first input timing generator
`205, and the clocking of the received signal. Similar opera
`tions may be performed on the Second through Nth input
`timing generators 205-205, So that each finger of the
`receiver can recover the Signal delayed by different amounts,
`Such as the delays caused by multipath (i.e., Scattering along
`different paths via reflecting off of local objects).
`0060 A feature of the transceiver in FIG. 2 is that it
`includes a plurality of tracking correlatorS 220-220. By
`providing a plurality of correlators, Several advantages are
`obtained. First, it is possible to achieve Synchronization
`more quickly (i.e., by operating parallel sets of correlation
`arms to find strong SNR points over different code-wheel
`Segments). Second, during a receive mode of operation, the
`multiple arms can resolve and lock onto different multipath
`components of a signal. Through coherent addition, the
`UWB communication system uses the energy from the
`different multipath Signal components to reinforce the
`received signal, thereby improving Signal to noise ratio.
`Third, by providing a plurality of tracking correlator arms,
`it is also possible to use one arm to continuously Scan the
`channel for a better Signal than is being received on other
`S.
`0061. In one embodiment of the present invention, if and
`when the Scanning arm finds a multipath term with higher
`SNR than another arm that is being used to demodulate data,
`the role of the arms is switched (i.e., the arm with the higher
`SNR is used to demodulate data, while the arm with the
`lower SNR begins Searching). In this way, the communica
`tions System dynamically adapts to changing channel con
`ditions.
`0062) The digital PMD 130 receives the information from
`the different correlators 220-220 and decodes the data.
`The digital PMD 130 also provides control signals for
`controlling the receiver front end 122, e.g., Such as gain,
`filter Selection, filter adaptation, etc., and adjusting the
`Synchronization and tracking operations by way of the
`timing generator module 205.
`0063) The digital PMD 130 is connected to the PLCP 140
`(not shown in FIG. 2), which serves as an interface between
`the communication link feature of the present invention and
`other higher level applications that will use the wireleSS
`UWB communication link for performing other functions.
`Some of these functions would include, for example, per
`forming range-finding operations, wireleSS telephony, file
`Sharing, personal digital assistant (PDA) functions, embed
`ded control functions, location-finding operations, etc.
`0.064 On the transmit portion of the transceiver shown in
`FIG. 2, an output timing generator 205 also receives phase,
`frequency and/or fast modulation adjustment Signals for use
`in encoding a UWB waveform from the digital PMD 130.
`Data and user codes (via a control signal) are provided to the
`encoder 225, which in the case of an embodiment of the
`present invention using time-modulation passes command
`
`Signals (e.g., At)