a2) United States Patent
`US 7,058,414 B1
`(0) Patent No.:
`Jun. 6, 2006
`(45) Date of Patent:
`Rofheartet al.
`
`US007058414B1
`
`(54) METHOD AND SYSTEM FOR ENABLING
`DEVICE FUNCTIONS BASED ON DISTANCE
`INFORMATION
`
`(75)
`
`Inventors: Martin Rofheart, Washington, DC
`(US); John W. McCorkle, Laurel, MD
`(US)
`
`(73) Assignee: Freescale Semiconductor, Inc., Austin,
`TX (US)
`
`(*) Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 649 days.
`
`(21) Appl. No.: 09/685,202
`
`(22)
`
`Filed:
`
`Oct. 10, 2000
`
`(60)
`
`(51)
`
`Related U.S. Application Data
`Provisional application No. 60/217,099, filed on Jul. 10,
`2000, and provisional application No. 60/207,225, filed on
`May 26, 2000.
`
`Int. Cl.
`H04Q 7/20
`
`(2006.01)
`
`(52) US. Ch oe 455/456.4; 455/411; 455/456.1;
`455/456.3
`
`(58) Field of Classification Search ................. 455/421,
`455/456.1, 456.4, 67.16, 456.2, 456.3, 456.5,
`455/456.6, 457; 340/539.1, 539.11, 539.13;
`342/453, 463, 464, 465
`See application file for complete search history.
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5,455,593 A * 10/1995 Ross
`5,748,891 A
`5/1998 Fleminget al.
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`WO
`
`10/1995
`0 676 650
`1/2000
`WO 00/04677
`OTHER PUBLICATIONS
`
`USS. Appl. No. 60/207,225, filed May 26, 2000, McCorkle.
`U.S. Appl. No. 60/217,099, filed Jul. 10, 2000, Miller.
`(Continued)
`Primary Examiner—David Hudspeth
`Assistant Examiner—Huy D Nguyen
`(74) Attorney, Agent, or Firm—Posz Law Group, PLC
`(57)
`ABSTRACT
`
`A method, device and computer readable medium for
`enabling and blocking communications with a remote device
`based on a distance of the remote device. The method on
`
`which the device and computer readable medium are based
`includes transmitting a message from a local device to a
`remote device via an ultra wide band (UWB) wireless
`medium and receiving a response from the remote device via
`the UWBwireless medium. The transmitting and receiving
`steps are preferably performed in accordance with a Media
`Access Control (MAC) protocol. A distance between the
`local device and the remote device is then determined based
`on a time between the transmitting of the message and the
`receiving of the response and a function, such as commu-
`nicating with the remote device, is performed in the local
`device based on the distance determined. The communica-
`
`tion between the local device and the remote device may be
`enabled or disabled depending on the distance that the
`remote device is from the local device. In addition, the
`distance information for a remote device may be continually
`updated, or updated only if communication to the remote
`device are blocked. A positional map may be generated
`based on distance data determined for a plurality of refer-
`ence points and the user mayselect the remote device from
`the positional map to enable communications to the posi-
`tional map.
`
`(Continued)
`
`3 Claims, 13 Drawing Sheets
`
`of RX Data In
`
`Generator
`
`Waveform
`
`TX Data Out
`
`APPLE 1009
`
`APPLE 1009
`
`1
`
`

`

`US 7,058,414 B1
` Page 2
`
`U.S. PATENT DOCUMENTS
`5,850,449 A
`1/1998 McManis
`5.878.034 A *
`3/1999 Hershey
`et al.
`:
`:
`y
`6.011.974 A *
`1/2000 Cedervall et al.
`6.115.409 A *
`9/2000 Upadhyayet al.
`6,195,705 Bl *
`2/2001 Leung
`6,351,246 Bl
`2/2002 McCorkle
`6,381,464 Bl *
`4/2002 Vannucci
`6,490,456 Bl * 12/2002 Bogdan etal.
`oo930 Bi
`ypod vecone
`+700,
`cCorkle
`6.735.238 Bl
`5/2004 MoCorkle
`OTHER PUBLICATIONS
`
`USS. Appl. No. 09/633,815, filed Aug. 7, 2000, McCorkle.
`USS. Appl. No. 60/238,466, filed Oct. 10, 2000, McCorkle.
`USS. Appl. No. 09/684,401, filed Oct. 10, 2000, Miller.
`
`USS. Appl. No. 09/684,782,filed Oct. 10, 2000, McCorkle.
`USS. Appl. No. 09/685,195, filed Oct. 10, 2000, Miller.
`USS. Appl. No. 09/685,196, filed Oct. 10, 2000, Miller.
`.
`USS. Appl. No. 09/685,197, Oct. 10, 2000, Miller.
`U.S. Appl. No. 09/685,198, filed Oct. 10, 2000, McCorkle.
`USS. Appl. No. 09/685,199, Oct. 10, 2000, McCorkle.
`USS. Appl. No. 09/685,200, filed Oct. 10, 2000, McCorkle.
`U.S. Appl. No. 09/685,203, Oct. 10, 2000, Miller.
`USS. Appl. No. 09/685,205, Oct. 10, 2000, McCorkle.
`R. Comerford, IEEE Spectrum, Wireless Internet, pp. 35-41,
`“
`:
`°°
`Handhelds Duke it out for the Internet”, Aug. 2000.
`G. A. Stobbs, et al.,
`IEEE Communications Magazine,
`Patent and Telecommunications, pp. 98-101, “Patenting
`Propagated Data Signals: What Hath God Wrought?”, Jul.
`2000.
`
`* cited by examiner
`
`2
`
`

`

`U.S. Patent
`
`Jun. 6, 2006
`
`Sheet 1 of 13
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`U.S. Patent
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`Jun. 6, 2006
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`Jun. 6, 2006
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`U.S. Patent
`
`Jun.6, 2006
`
`Sheet 5 of 13
`
`US 7,058,414 B1
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`a
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`15
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`300
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`15
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`7
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`

`

`U.S. Patent
`
`Jun.6, 2006
`
`Sheet 6 of 13
`
`US 7,058,414 B1
`
`(SEEFIG.6)
`
`LOCAL DEVICE ESTABLISHES A UNIQUE LINK
`WITH UNLINKED REMOTE DEVICES USING
`MEDIA ACCESS CONTROL (MAC) PROTOCOL
`
`411
`
`
`
`
`
`LOCAL DEVICE DETERMINESDISTANCE TO
`EACH LINKED REMOTE DEVICE AND
`COMMUNICATES WITH EACH LINKED
`
`REMOTE DEVICE BASED ON DISTANCES
`
`DETERMINED
`
`(SEE FIGURES 7 AND 9-11)
`
`
`
`
`
`401
`
`403
`
`LOCAL DEVICE DETERMINES AND DROPS REMOTE
`,
`DEVICES THAT HAVE EXITED NETWORK
`
`v
`
`405
`
`V
`
`FIGURE 4
`
`8
`
`

`

`U.S. Patent
`
`Jun.6, 2006
`
`Sheet 7 of 13
`
`US 7,058,414 B1
`
`Y
`
`TRANSMIT JOIN MESSAGE FROM LOCAL
`DEVICE TO UNLINKED REMOTE DEVICES
`
`501
`
`503
`
`505
`
`V/
`
`RECEIVE JOIN MESSAGEIN UNLINKED
`REMOTE DEVICES AND SYNCHRONIZE
`
`WITH LOCAL DEVICE
`
`
`
`
`IN EACH UNLINKED REMOTEDEVICE,
`ENCODEA UNIQUE IDENTIFIER AND
`TRANSMIT AS A REPLY TO LOCAL DEVICE
`
`RECEIVE EACH REPLY IN LOCAL
`DEVICE AND SYNCHRONIZE WITH
`
`EACH UNLINKED REMOTE DEVICE
`
`507
`
`DECODE EACH UNIQUE IDENTIFIER IN LOCAL DEVICE AND
`ESTABLISH A UNIQUE COMMUNICATIONSLINK WITH
`EACH REMOTE DEVICE BASED ON THE UNIQUE
`
`IDENTIFIERS
`
`509
`
`FIGURE 5
`
`9
`
`

`

`U.S. Patent
`
`Jun.6, 2006
`
`Sheet 8 of 13
`
`US 7,058,414 B1
`
`LOCAL DEVICE DETERMINES DISTANCE TO
`
` EACH LINKED REMOTEDEVICES
`
`(SEEFIG.7)
`
`
`
`
`
`SET AUTHENTICATION CRITERIA
`OF LOCAL DEVICE
`EG. D<r OR rl <D < R2 OR D=R ETC.
`
`
`
`
`
`601
`
`603
`
`605 607
`WITH DEVICES NOT
`
`COMPARE
`
`
`AUTHENTICATION
`CRITERIA WITH
`
`DETERMINED
`DISTANCES
`
`SATISFIED
`
`BLOCK
`COMMUNICATIONS
`
`SATISFIED
`
`611
`
`609
`
`ENABLE
`COMMUNICATIONS
`
`COMMUNICATE
`WITH ENABLED
`
`WITH DEVICES DEVICES
`
`FIGURE 6
`
`607 <
`
`505
`
`
`
`
`
`
`DETERMINE AND
`DROP REMOTE
`DEVICES THAT
`HAVE EXCITED
`NETWORK
`
`10
`
`10
`
`

`

`U.S. Patent
`
`Jun.6, 2006
`
`Sheet 9 of 13
`
`US 7,058,414 B1
`
`TRANSMIT A DISTANCE DETERMINING MESSAGE FROM
`LOCAL DEVICE TO EACH LINKED REMOTE DEVICE VIA
`
`
`
` UNIQUE LINKS
`
`V
`MARK TRANSMITTING TIME FOR TRANSMISSION
`ON EACH UNIQUE LINK AS#1
`
`701
`
`703
`
`705
`
`V
`
`RECEIVE DISTANCE DETERMINING MESSAGEIN
`EACH LINKED REMOTE DEVICE AND TRANSMIT A
`RESPONSE FROM EACH REMOTE DEVICE VIA
`
`RESPECTIVE UNIQUE LINKS
`DEVICE VIA RESPECTIVE UNIQUE LINKS
`
`RECEIVE EACH RESPONSE IN LOCAL
`
`707
`
`V
`
`MARK RECEIVING TIME FOR EACH RECEPTION
`ON EACH UNIQUE LINK AS ¢2
`
`L
`
`DETERMINE PROCESSING DELAY FOR EACH.
`LINKED REMOTEDEVICEASd.
`
`709
`
`711
`
`COMPUTE ROUND TRIP TIME 7rt FOR EACH
`LINKED REMOTE DEVICE
`Trt=t2-tl-d
`
`D=Cx Trt/2
`
`COMPUTE DISTANCE D TO EACH
`LINKED REMOTE DEVICE
`
`FIGURE 7
`
`11
`
`11
`
`

`

`U.S. Patent
`
`Jun.6, 2006
`
`Sheet 10 of 13
`
`US 7,058,414 B1
`
`FIGURE 8
`
`DETERMINE DISTANCE TO LINKED
`REMOTE DEVICES
`(SEE FIG.8)
`
`803
`
`
`
`SET AUTHENTICATION CRITERIA
`OF LOCAL DEVICE
`
`EG. D<r OR rl <D<R2 OR D=R ETC.
`
`805
`
`807
`
`SATISFIED”
`
`NOT
`SATISFIED
`COMPARE CRITERIA
`
`WITH DETERMINED
`DISTANCE
`
`809
`
`
`
`
`
`
`
`
`
`COMMUNICATIONSbe
`
`
`ENABLE
`
`COMMUNICATIONS
`BLOCK
`
`
`
`STORE UNIQUE
`IDENTIFIER TO ID
`
`LIST INMEMORY
`
`
`
`
`
`DETERMINE AND DROP
`
`
`REMOTE DEVICES THAT
`HAVE EXCITED NETWORK
`
`COMMUNICATE
`WITH ENABLED
`DEVICES
`
`507<1
`
`505
`
`12
`
`12
`
`

`

`U.S. Patent
`
`Jun.6, 2006
`
`Sheet 11 of 13
`
`US 7,058,414 B1
`
`FIGURE 9
`
`
`
`13
`
`13
`
`

`

`U.S. Patent
`
`Jun.6, 2006
`
`Sheet 12 of 13
`
`US 7,058,414 B1
`
`(3)
`
`V
`
`1001
`
`DETERMINE DISTANCE TO REMOTEDEVICES
`(SEE FIG.7)
`
`Y
`
`TRANSMIT A POSITION DETERMINING MESSAGE FROM
`LOCAL DEVICE TO EACH LINKED REMOTEDEVICE VIA
`
`RESPECTIVE LINKS
`
`1003
`
`
`
`RECEIVE POSITION DETERMINING MESSAGEIN EACH
`
`
`LINKED REMOTE DEVICE AND TRANSMIT AN ANSWER
`INCLUDINGPOSITION DATA FROM EACH LINKED REMOTE
`DEVICE VIA RESPECTIVE UNIQUE LINKS
`
`
`
`1005
`
`RECEIVE EACH ANSWERIN LOCAL
`DEVICE VIA RESPECTIVE UNIQUE
`
`LINKS
`DISPLAY REMOTE DEVICES ON LOCAL DISPLAY
`
`DETERMINE POSITION OF EACH LINKED
`REMOTE DEVICE BY TRIANGULATION AND
`
`Vv
`
`1014
`
`1007
`
`1009
`
`1015
`
`BLOCK
`COMMUNICATIONS
`WITH NON
`
`
`
`
`
`POSITION
`
`
`SELECTED?
`
`
`
`
`
`
`SELECTED 1
`ENABLE COMMUNICATIONS
`WITH SELECTED DEVICES
`
`COMMUNICATE WITH
`SELECTED DEVICES
`
`
`FIGURE 10 » <
`
`505
`
`
`
`DETERMINE AND DROP
`REMOTE DEVICES THAT
`HAVE EXCITED NETWORK
`
`
`
`14
`
`14
`
`

`

`U.S. Patent
`
`Jun.6, 2006
`
`Sheet 13 of 13
`
`US 7,058,414 B1
`
`
`
`
`
`TRANSMIT REQUEST FOR SECURED
`COMMUNICATIONSINCLUDING PUBLIC
`
`
`
`KEY FROM LOCAL DEVICE TO ENABLED
`REMOTE DEVICES
`
`1101
`
`
`
`
`
`
`RECEIVE PUBLIC KEY AND REQUEST
`FOR SECURED COMMUNICATIONSIN
`ENABLED REMOTE DEVICES
`
`
`
`1103
`
`ow
`
`ENCRYPT DATA USING PUBLIC KEY
`AND ALGORITHM AND TRANSMIT
`ENCRYPTED DATA FROM EACH
`
`ENABLED REMOTE DEVICE
`
`1105
`
`vw
`
`1107
`RECEIVE ENCRYPTED DATA IN LOCAL|_/~/
`DEVICE
`
`V
`
`DECRYPTE DATA
`
`OBTAIN PRIVATE KEY AND
`
`1109
`
`FIGURE 11
`
`15
`
`15
`
`

`

`US 7,058,414 B1
`
`1
`METHOD AND SYSTEM FOR ENABLING
`DEVICE FUNCTIONS BASED ON DISTANCE
`INFORMATION
`
`CROSS-REFERENCE TO RELATED PATENT
`DOCUMENTS
`
`This application claims benefit of priority to U.S. Provi-
`sional Application Nos. 60/207,225 and 60/217,099 filed in
`the United States Patent and Trademark Office on May 26,
`2000 and Jul. 10, 2000, respectively
`The present document contains subject matter related to
`that disclosed in commonly owned, co-pending application
`Ser. No. 09/209,460 filed Dec. 11, 1998, entitled ULTRA
`WIDE BANDWIDTH SPREAD-SPECTRUM COMMU-
`
`NICATIONS SYSTEM; Ser. No. 09/633,815 filed Aug. 7,
`2000, entitled ELECTRICALLY SMALL PLANAR UWB
`ANTENNA;application Ser. No. 09/563,292, filed May 3,
`2000, entitled PLANAR ULTRA WIDE BAND ANTENNA
`WITH INTEGRATED ELECTRONICS; application Ser.
`No. 60/207,22 filed May 26, 2000, entitled ULTRA WIDE-
`BAND COMMUNICATION SYSTEM AND METHOD;
`application Ser. No. 09/685,198 filed Oct. 10, 2000, entitled
`ANALOG SIGNAL SEPARATOR FOR UWB VERSUS
`
`NARROWBANDSIGNALS; application Ser No. 60/238,
`466 filed Oct. 10, 2000, entitled ULTRA WIDE BAND-
`WIDTH NOISE CANCELLATION MECHANISM AND
`
`METHOD; application Ser. No. 60/217,099 filed Jul. 10,
`2000, entitled MULTIMEDIA WIRELESS PERSONAL
`AREA WORK (WPAN) PHYSICAL LAYER SYSTEM
`AND METHOD; application Ser. No. 09/685,203 filed Oct.
`10, 2000, entitled SYSTEM AND METHOD FOR BASE-
`BAND REMOVAL OF NARROWBAND INTERFER-
`
`ENCEIN ULTRA WIDEBANDSIGNALS; application Ser.
`No. 09/685,197 Oct. 10, 2000, entitled MODE CONTROL-
`LER FOR SIGNAL ACQUISITION AND TRACKING IN
`AN ULTRA WIDEBAND COMMUNICATION SYSTEM;
`application Ser. No. 09/684,400 filed Oct. 10, 2000, entitled
`ULTRA WIDEBAND COMMUNICATION SYSTEM,
`METHOD, AND DEVICE WITH LOW NOISE PULSE
`FORMATION; application Ser. No. 09/685,195 filed Oct.
`10, 2000, entitled ULTRA WIDE BANDWIDTH SYSTEM
`AND METHOD FOR FAST SYNCHRONIZATION;appli-
`cation Ser. No. 09/684,401 filed Oct. 10, 2000, entitled
`ULTRA WIDE BANDWIDTH SYSTEM AND METHOD
`FOR FAST SYNCHRONIZATION USING SUB CODE
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`2
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The present invention relates generally to a method and
`system for enabling device functions, and more specifically
`to a method and system for enabling communications func-
`tions in a local wireless device based on a distance between
`the local wireless device and a remote wireless device.
`
`2. Discussion of the Background
`The recent proliferation of hand held computers has made
`data exchange between wireless devices such as mobile
`phones, laptops, and hand held devices more common. In
`this proliferation, various wireless communications tech-
`nologies including infrared technology andradio frequency
`(RF) technology have emerged to provide the wireless
`connectivity between devices. With regard to infrared
`technology, the Infrared Data Association (IrDA) has speci-
`fied several infrared communications standards to provide
`the wireless connectivity necessary for data exchange
`between devices. IrDA is a point to point narrow angle ad
`hoc data transmission standard designed to operate at dis-
`tances of 1 meter or so. In the area of RF connectivity, Blue
`tooth technology has been recently proposed as an RF
`specification for providing a wireless communications link
`between devices. Blue tooth employs an omnidirectional
`signal transmitted at 2.4 GHz and provides a normal link
`range 10 cm to 10 m in non-line of sight transmission
`through solid objects such as walls and other structures.
`A common wireless data exchange scenario is one in
`which the exchange will take place in a room containing a
`number of other wireless devices making similar data
`exchanges. An example is an electronic business card
`exchange where two people meet to exchange business
`cards, face to face, in a large conference room where many
`other people carrying wireless devices are also presentin the
`room and making similar exchanges. As another example, a
`person may want to download photographs from a digital
`camera to a wireless kiosk in a retail store where other
`digital cameras and wireless devices are exchanging data. In
`each ofthese situations, the wireless devices of the intended
`transaction must provide some way offiltering the data of
`the intended transaction from other data in the area. Thatis,
`the devices of the business card exchange must provide
`some way of sending and receiving only the intended
`business card and blocking other business cards that are
`being exchangedin the conference room,and the kiosk must
`be able to distinguish the intended photographs from other
`data.
`
`SPINS; application Ser. No. 09/685,196 filed Oct. 10, 2000,
`entitled ULTRA WIDE BANDWIDTH SYSTEM AND
`METHOD FOR FAST SYNCHRONIZATION USING
`The IrDA infrared technology provides suchafiltering
`50
`MULTIPLE DETECTION ARMS; application Ser. No.
`function by requiring the users of the device to “point and
`09/685,199 filed Oct. 10, 2000, entitled A LOW POWER,
`shoot” the electronic data from the sending device to the
`HIGH RESOLUTION TIMING GENERATOR FOR
`intended receiving device. The limited range and narrow
`ULTRA-WIDE BANDWIDTH COMMUNICATIONSYS-
`beam width of IrDA provides a wayoffiltering out unin-
`tended signals and ensuring communications only between
`intended devices.
`In the examples discussed above,
`the
`sender of an electronic business card would simply position
`his device within one meterof the receiving device, and then
`pointed directly at the receiving device and press a send
`button that transmits the electronic business card to the
`
`TEMS; application Ser. No. 09/685,201 filed Oct. 10, 2000,
`entitled CARRIERLESS ULTRA WIDEBAND WIRELESS
`SIGNALS FOR CONVEYING APPLICATION DATA;
`application Ser. No. 09/685,205 filed Oct. 10, 2000, entitled
`SYSTEM AND METHOD FOR GENERATING ULTRA
`
`55
`
`WIDEBAND PULSES; application Ser. No. 09/684,782
`filed Oct. 10, 2000, entitled ULTRA WIDEBAND COM-
`MUNICATION SYSTEM, METHOD, AND DEVICE
`WITH LOW NOISE RECEPTION;andapplication Ser. No.
`09/685,200 filed Oct. 10, 2000, entitled LEAKAGE NULL-
`ING RECEIVER CORRELATOR STRUCTURE AND
`METHOD FOR ULTRA WIDE BANDWIDTH COMMU-
`NICATION SYSTEM,the entire contents of each of which
`being incorporated herein by reference.
`
`60
`
`65
`
`receiving device on an infrared beam. The camera owner
`would similarly point and shoot the photographs to the
`kiosk. As recognized by the present inventors, the infrared
`system is problematic, however, in that the infrared devices
`must be placed in a fixed location of close proximity and
`precise orientation while synchronization and data exchange
`takes place between the two devices. This positioning makes
`transactions with fixed structure devices such as the kiosk
`
`16
`
`16
`
`

`

`US 7,058,414 B1
`
`4
`Access Control (MAC)protocol. A time between the trans-
`mitting of the message andthe receiving of the responseis
`then determined and a function is performed in the local
`device based on the roundtrip time determined.
`According to another aspect of the invention, the time
`between the transmitting of the message andthe receiving of
`the response may be used to determine a distance from the
`local device to the remote device. In this aspect, the time
`between the transmitting of the message andthe receiving of
`the response is determined by marking a time ofthe trans-
`mitting and receiving as a first
`time and second time
`respectively, and determining a difference between thefirst
`and second times. A roundtrip time is then determined by
`subtracting a processing delay from the difference between
`the first and second times. The processing delay may be
`obtained from a memory ofthe local device or received from
`the remote device. Finally, the distance from the local device
`to the remote device is determined by multiplying one half
`of the round trip time by a speed of transmission over the
`wireless medium.In this aspect, the function performed in
`the local device is communicating with the remote device
`based on the distance determined.
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`inconvenient. Moreover, IrDa technology requires that the
`data exchanging devices be withinline of sight of each other
`making it impossible for one device to transmit an electronic
`business card to another device located in the intended
`recipients pocket or briefcase. A deficiency observed by the
`present inventors is that the line-of-sight nature of infrared
`communication links is that it requires the user’s vision is a
`necessary step to properly orient the IR transmission beam.
`Thus, avoiding the possibility of being used effectively by
`visually impaired people, by remote “un-manned” equip-
`ment or in other scenarios where manual beam pointing is
`inconvenient or impossible.
`On the other hand, the characteristics of the omnidirec-
`tional RF signal devices such as Blue tooth devices allows
`communication over relatively far distances and provides
`signals that penetrate solid objects. Therefore, RF devices
`provide maximum mobility for the user and the capability to
`communicate with obstructed devices. In order to distin-
`guish intended data from unintended data, the RF device
`must perform a discovery operation that will find many
`sending devices other than the intended device. While these
`In another aspect of the present invention, communicating
`additional capabilities carry great benefits for the user, one
`with the remote device based on the distance determined
`problem is that the user is then forced to choose fromalist
`includessetting an authenticationcriteria in the local device,
`of discovered devices which requires special information
`25
`comparing the authentication criteria with the distance from
`about the sending device such as a device bit address or
`name that
`is associated with the user of the device.
`the local device to the remote device, and enabling or
`blocking communications with the remote device depending
`on whether the distance satisfies the authenticationcriteria.
`
`Moreover, because modem RF devices have multipoint
`capabilities and therefore utilize security mechanisms to
`prevent unauthorized access, the users of the devices of the
`intended exchange may also have to execute security mea-
`sures. These proceduresare time consuming and impractical
`for many data exchanges such as the typical electronic
`business card and photo exchange discussed above.
`SUMMARY OF THE INVENTION
`
`Consistent with the title of this section, only a brief
`non-limiting description of the invention, and selected fea-
`tures of the invention is now provided. To appreciate all of
`the facets and features of the present invention it is recom-
`mended that the entire document be read.
`
`Accordingly, one object of this invention is to provide a
`method, system and computer program product for enabling
`communications between wireless devices without the need
`for close proximity fixed orientation between the wireless
`devices.
`
`Another object of the present invention is to provide a
`method, system and computer program product for enabling
`communications between wireless devices without the need
`for users of the devices to manually select an intended
`sending device.
`Yet another object of this invention is to provide a
`method, system and computer program product for enabling
`wireless device communications functions based on the
`distance between wireless devices.
`
`These and other objects that overcome the above-
`identified features of conventional systems and methodsare
`achieved by providing a novel method, apparatus, and
`computer program product for enabling device functions
`based on distance information.
`
`According to one aspect of the invention, the method, on
`which the device and computer program product are based
`includes transmitting a message from a local device to a
`remote device via an ultra wide band (UWB) wireless
`medium andreceiving a response from the remote device via
`the UWBwireless medium. The transmitting and receiving
`steps are preferably performed in accordance with a Media
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`In this aspect, information of the distance from the local
`device to the remote device maybe periodically updated and
`communications with the remote device may be enabled or
`blocked based on the updated information. Alternatively, the
`distance information is periodically updated only when
`communications to the remote device are blocked and
`communications are enabled for the blocked remote device
`
`based on the updated information.
`According to yet another aspect of the present invention,
`communicating with the remote device based on the distance
`determined includes determining a position of the remote
`device and enabling communications with the remote device
`based on the position determined. In this aspect, the position
`of the remote device is determined by determining a distance
`from the local device to a reference point, receiving infor-
`mation from the remote device indicating a distance from
`the remote device to the reference point and triangulating the
`position of the remote device based on the known distances.
`The local and remote devices may be displayed on a
`positional map including on a display of the local device and
`the position of these devices may be periodically changed
`based on updated positional information. The user of the
`local device may select a remote device by a touch screen
`input to the remote device and selected devices are indicated
`on the display as positional information is updated. In a
`variation of this aspect, the local device may determine the
`position of the remote device using a plurality of reference
`points each of which is positioned due north, south east or
`west of a center point of the area where the local device is
`located. Using an internal compass, the local device is then
`able to orient a positional map on the display in accordance
`with the direction that the local device is facing.
`In any of the above aspects, the local device may com-
`municate with a plurality of remote devices based on dis-
`tance and may communicate on a secured link.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Amore complete appreciation of the invention and many
`of the attendant advantages thereof will be readily obtained
`
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`

`US 7,058,414 B1
`
`5
`as the same becomes better understood by reference to the
`following detailed description when considered in connec-
`tion with the accompanying drawings, wherein:
`FIG.1a is a block diagram of an ultra-wide band (UWB)
`transceiver, according to the present invention;
`FIG. 18 is a diagram for illustrating the operation of the
`transceiver of FIG. la, according to the present invention;
`FIG. 1c is a block diagram of the transceiver of FIG. 1a,
`that manipulates a shape of UWBpulses, according to the
`present invention;
`FIG. 2 illustrates a processor system upon which an
`embodiment according to the present
`invention may be
`implemented;
`FIG. 3 is a wireless network in which a plurality of
`wireless devices may exchange information according to an
`embodimentof the present invention;
`FIG. 4 is a general flow chart describing a process for
`communicating with remote wireless devices based on dis-
`tance information in accordance with an embodimentof the
`
`present invention;
`FIG.5 is a flow chart describing the process of establish-
`ing a link with remote devices using a media access control
`(MAC)protocol in accordance with the present invention;
`FIG.6 is a flow chart describing a process for determining
`distance to linked remote devices and communicating with
`the remote devices based on distance in accordance with an
`embodiment of the present invention.
`FIG.7 is a flow chart describing the process of determin-
`ing distance to a remote device in accordance with an
`embodimentof the present invention;
`FIG. 8 describes process wherein a local device remem-
`bers enabled remote devices and communicates with remote
`devices based on distance in accordance with an embodi-
`
`ment of the present invention; and
`FIG. 9 illustrates a typical conference room in which a
`plurality of remote devices communicate based on distance
`and positioned information in accordance with an embodi-
`ment of the present invention;
`FIG. 10 shows a process for enabling and disabling
`communications with remote devices based on selections
`
`madeon a positional map obtained from distance informa-
`tion in accordance with the present invention; and
`FIG. 11 describes a process for providing secured com-
`munications with remote devices in accordance with the
`present invention.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`Referring now to the drawings and more particularly to
`FIG. 1a thereof, a block diagram of an ultra-wide band
`(UWB)transceiver used in accordance with the present
`invention is shown.In FIG.1a,the transceiver includes three
`major components, namely, receiver 11, radio controller and
`interface 9, and transmitter 13. Alternatively, the system may
`be implemented as a separate receiver 11 and radio control-
`ler and interface 9, and a separate transmitter 13 and radio
`controller and interface 9. The radio controller and interface
`
`9 serves as a media access control (MAC) interface between
`the UWB wireless communication functions implemented
`by the receiver 11 and transmitter 13 and applications that
`use the UWB communications channel for exchanging data
`with remote devices.
`The receiver 11 includes an antenna 1 that converts a
`
`UWBelectromagnetic waveform into an electrical signal (or
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`optical signal) for subsequent processing. The UWBsignal
`is generated with a sequence of shape-modulated wavelets,
`where the occurrence times of the shape-modulated wavelets
`mayalso be modulated. For analog modulation, at least one
`of the shape control parameters is modulated with the analog
`signal. More typically,
`the wavelets take on M possible
`shapes. Digital
`information is encoded to use one or a
`combination of the M wavelet shapes and occurrence times
`to communicate information.
`
`In one embodimentof the present invention, each wavelet
`communicates one bit, for example, using two shapes such
`as bi-phase. In other embodiments of the present invention,
`each wavelet may be configured to communicate nn bits,
`where M=2””. For example, four shapes may be configured
`to communicate two bits, such as with quadrature phase or
`four-level amplitude modulation. In another embodiment of
`the present invention, each wavelet is a “chip” in a code
`sequence, where the sequence, as a group, communicates
`one or more bits. The code can be M-ary at the chip level,
`choosing from M possible shapes for each chip.
`Atthe chip, or wavelet level, embodiments of the present
`invention produce UWB waveforms. The UWB waveforms
`are modulated by a variety of techniques including but not
`limited to:
`(i) bi-phase modulated signals (+1, -1), (i)
`multilevel bi-phase signals (+1,
`-1, +al, -al, +a2,
`-a2,..., +aN, -aN, (iii) quadrature phase signals (+1, -1,
`+j, -j), Gv) multi-phase signals (1, -1, exp(+ja/N), exp(-
`ja/N), exp(+j2/N), exp(-jm2/N),
`.
`.
`.
`, exp(4j(N-1)/N),
`exp(-ja(N-1)/N)),
`(v) multilevel multi-phase signals (a;
`exp(j2mB/N)| a E{1, al, a2,..., aK}, BE{O, 1, ..., N-1}),
`(vi) frequency modulated pulses, (vii) pulse position modu-
`lation (PPM)signals (possibly same shape pulse transmitted
`in different candidate time slots), (viii) M-ary modulated
`waveforms g,, (t) with B,
`€{1,
`..., M}, and (ix) any
`combination of the above waveforms, such as multi-phase
`channel symbols transmitted according to a chirping signal-
`ing scheme. The present invention, however, is applicable to
`variations of the above modulation schemes and other
`modulation schemes(e.g., as described in Lathi, “Modem
`Digital and Analog Communications Systems,” Holt, Rine-
`hart and Winston, 1998, the entire contents of which is
`incorporated by reference herein), as will be appreciated by
`those skilled in the relevant art(s).
`Some exemplary waveforms and characteristic equations
`thereof will now be described. The time modulation
`
`component, for example, can be defined as follows. Let t; be
`the time spacing between the (i-1)” pulse andthe i” pulse.
`Accordingly, the total time to the i” pulse is
`i
`T)) tj.
`J=0
`
`The signal T, could be encoded for data, part of a spreading
`code or user code, or some combination thereof. For
`example, the signal T, could be equally spaced, or part of a
`spreading code, where T, corresponds to the zero-crossings
`of a chirp, i.e., the sequence of T,’s, and where
`
`for a predetermined set of a and k. Here, a and k may also
`be chosen from a finite s based on the user code or encoded
`data.
`An embodimentofthe present invention can be described
`using M-ary modulation. Equation 1 below can be used to
`
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`

`

`US 7,058,414 B1
`
`7
`represent a sequence of exemplary transmitted or received
`pulses, where each pulse is a shape modulated UWB
`wavelet, g,, (t-T).
`
`<2
`x) = >) g5,0-T)
`i=0
`
`wD
`
`In the above equation,the subscripti refers to the i” pulse
`in the sequence of UWBpulses transmitted or received. The
`wavelet function g has M possible shapes, and therefore B,
`represents a mapping from the data, to one of the M-ary
`modulation shapes at the i” pulse in the sequence. The
`wavelet generator hardware(e.g., the UWB waveform gen-
`erator 17) has several control lines (e.g., coming from the
`radio controller and interface 9) that govern the shape of the
`wavelet. Therefore, B, can be thought of as including a
`lookup-table for the M combinations of control signals that
`produce the M desired wavelet shapes. The encoder 21
`combines the data stream and codes to generate the M-ary
`states. Demodulation occurs in the waveform correlator 5
`and the radio controller and interface 9 to recover to the
`
`original data stream. Time position and wavelet shape are
`combined into the pulse sequence to convey information,
`implement user codes, etc.
`In the above case, the signal is comprised of wavelets
`from i=1 to infinity. As i
`is incremented, a wavelet
`is
`produced. Equation 2 below can be used to represent a
`generic wavelet pulse function, whose shape can be changed
`from pulse to pulse to convey information or implement user
`codes, etc.
`
`82,(Q=ReBi1)Sa,5.3;5 “ - O4IMB,Sha,a3,.. 0
`
`(2)
`
`In the above equation, function f defines a basic wavelet
`shape, and function h is simply the Hilbert transform of the
`function f. The parameterB,, is a complex numberallowing
`magnitude and phase of each wavelet pulse to be adjusted,
`i.e., B,,=a,20,, where a,
`is selected from a finite set of
`amplitudes and 0, is selected from a finite set of phases. The
`parameters {B,,, B,3,
`.
`.
`. } represent a generic group of
`parameters that control the wavelet shape.
`An exemplary waveform sequence x(t) can be based on a
`family of wavelet pulse shapes f that are derivatives of a
`Guassian waveform as defined by Equation 3 below.
`
` o oeBiol|
`fa;= ¥(Bir, asl 7
`
`(3)
`
`In the above equation, the function W( ) normalizes the
`peak absolute value of f,,(t) to 1. The parameter B,
`controls the pulse duration and center frequency. The param-
`eter B,;
`is the number of derivatives and controls the
`ban