USOO8477731B2
`
`(12) United States Patent
`Nanda et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,477,731 B2
`Jul. 2, 2013
`
`(54)
`
`(75)
`
`(73)
`
`METHOD AND APPARATUS FOR LOCATING
`A WIRELESS LOCAL AREANETWORK INA
`WIDE AREANETWORK
`
`Inventors: Sanjiv Nanda, Ramona, CA (US);
`Aleksandar Gogic, San Diego, CA
`(US); Manoj M. Deshpande, San Diego,
`CA (US); Nikhil Jain, Mendham, NJ
`(US)
`Assignee: QUALCOMM Incorporated, San
`Diego, CA (US)
`
`(*)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 457 days.
`
`(21)
`(22)
`(65)
`
`(60)
`
`(51)
`
`(52)
`
`(58)
`
`Appl. No.: 11/355,540
`
`Filed:
`
`Feb. 15, 2006
`
`Prior Publication Data
`US 2007/OO1958.6 A1
`Jan. 25, 2007
`
`Related U.S. Application Data
`Provisional application No. 60/702,591, filed on Jul.
`25, 2005, provisional application No. 60/750,920,
`filed on Dec. 16, 2005, provisional application No.
`60/750,919, filed on Dec. 16, 2005.
`
`(2009.01)
`
`Int. C.
`H0474/00
`U.S. C.
`USPC ............................ 370/332: 370/335; 370/491
`Field of Classification Search
`USPC ............... 370/335, 320, 342, 441; 455/4.56.1,
`455/424, 446, 434, 440, 437, 456
`See application file for complete search history.
`
`
`
`(56)
`
`References Cited
`
`CN
`GB
`
`U.S. PATENT DOCUMENTS
`5,093.926 A * 3/1992 Sasuta ........................... 455,515
`5,365,451 A 1 1/1994 Wang et al.
`5,392.458 A * 2/1995 Sasuta et al. ............... 455,432.3
`5.437,053 A * 7/1995 Sawa et al. ...
`... 455,551
`5,917,811 A * 6/1999 Weaver et al. ................ 370,332
`6,134,523 A 10/2000 Nakajima et al.
`6,167.268 A * 12/2000 Souissi et al. ................. 455,434
`6,714,597 B1
`3/2004 Antonio et al.
`6,915,123 B1
`7/2005 Daudelin et al.
`(Continued)
`FOREIGN PATENT DOCUMENTS
`1642O76 A
`7/2005
`2321162. A * 7, 1998
`(Continued)
`OTHER PUBLICATIONS
`International Search Report—PCT/US06/028731—International
`Search Authority, European Patent Office—Dec. 11, 2006.
`(Continued)
`Primary Examiner — Ayaz Sheikh
`Assistant Examiner — Faiyazkhan Ghafoerkhan
`(74) Attorney, Agent, or Firm — Kam T. Tam
`(57)
`ABSTRACT
`The disclosure is directed to a mobile communication device
`that measures characteristics or attributes of a first commu
`nications network that vary according to physical location
`within that first communications network to create a finger
`print, or signature, of a location within the first communica
`tions network. When the fingerprint of the current location of
`the mobile device is created it can be compared to a known
`fingerprint associated with a second communication network
`to determine the mobile device's proximity to the second
`communications network. For example, the first communica
`tions network may be a CDMA wide area wireless commu
`nication network and the second communications network
`may be a 802.11 wireless LAN.
`37 Claims, 5 Drawing Sheets
`
`USER INITIATES A
`FINGERPRINT CAPTRE
`
`DEVICE MEASURES
`ATTRIBUTES OF FINGERPRINT
`
`EVICESTORES INFORMATION
`ABOUT FINGERPRINT AND
`WRELESS LAN
`
`Page 1 of 15
`
`SAMSUNG EX-1006
`
`

`

`US 8,477,731 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`7.440,755 B2 * 10/2008 Balachandran et al. ... 455/435.2
`2002/0177460 A1* 1 1/2002 Beasley et al. .....
`... 455,5O2
`2003/0045299 A1* 3, 2003 New ............
`455,455
`2003/0054813 A1* 3/2003 Riley et al. .
`... 455,424
`2003/0201931 A1* 10, 2003 Durst et al. .
`342,357.07
`2004/0012519 A1
`1/2004 Durst et al. .............. 342,357.07
`2004.0102969 A1
`5/2004 Manjunath et al.
`2004/0185873 A1* 9, 2004 Gilkes et al. ............... 455,456.2
`2004/0259546 A1 12/2004 Balachandran et al.
`2004/0260542 Al 12/2004 Ananthapadmanabhan et al.
`2005/O130677 A1 ck
`6, 2005 Meunier et al. .
`.
`.
`.
`.
`.
`.
`.
`.
`.
`. 455,456.6
`2005/013.6845 A1
`6/2005 Masuoka et al.
`455/67.14
`2005/0246334 A1* 11/2005 Tao et al. .......................... 707/5
`2006/0025 158 A1
`2/2006 Leblanc et al. ............ 455,456.2
`2006/0058056 A1
`3f2006 Das et al. ...................... 455,524
`2007/0021126 A1
`1/2007 Nanda et al.
`2008/00391 14 A1
`2/2008 Phatak et al. .............. 455,456.1
`
`
`
`GB
`JP
`JP
`JP
`
`RU
`RU
`TW
`WO
`WO
`
`FOREIGN PATENT DOCUMENTS
`2368240 A
`4/2002
`2002O10325
`1, 2002
`2003.198566
`11, 2003
`2005.509136
`4/2005
`2005.3's
`SS
`2157591
`10, 2000
`20031278239 A
`3, 2005
`I227644
`2, 2005
`WO9619887
`6, 1996
`WOO162034 A1 * 8, 2001
`
`12/2003
`O31.01138
`WO
`3.
`W. w838. A1
`T 2004
`WO WO2004.057360
`WO WO2004112317 A1 12/2004
`WO
`WO2005062066 A2
`7/2005
`
`ck
`
`OTHER PUBLICATIONS
`
`Junius Metal: “New Methods for Processing GSM Radio Measure
`ment Data: Applications for Locating, Handover and Network Man
`t”. P
`di
`f the Vehicular Technol
`Conf
`agemen
`OC Ings O
`e
`Ca CC O ogy OC.
`Stockholm, vol. 1 Conf.44, pp.338-342, Jun. 8, 1994.XP000496691.
`Taiwan Search Report TWO95127124 TIPO May 18, 2011.
`Junius Metal: “New Methods for Processing GSM Radio Measure
`ment Data Applications for Locating, Handover and Network Man
`agement'. Proceedings of the Vehicular Technology Congerence.
`Stockholm, vol. 1 Conf. 44, pp. 338-342, Jun. 8, 1994.
`IEEE 802.11 i. 2004, “Part 11: Wireless LAN Medium Access Con
`trol (MAC) and Physical Layer (PHY) specifications”, IEEE Stan
`dard 802.11i, Jul. 2004.
`International Search Report—PCT/US08/028731—International
`Search Authority, European Patent Office—Dec. 11, 2006.
`Written
`Opinion PCT/US06/028731–International
`Authority, European Patent Office—Dec. 11, 2006.
`International Preliminary Report on Patentability—PCT/US06/
`028731—The International Bureau of WIPO, Geneva, Switzer
`land–Jan. 29, 2008.
`
`Search
`
`* cited by examiner
`
`Page 2 of 15
`
`

`

`U.S. Patent
`U.S. Patent
`
`Jul. 2, 2013
`Jul. 2, 2013
`
`Sheet 1 of 5
`Sheet 1 of 5
`
`US 8,477,731 B2
`
`AVTATTHO
`
`WLOA.LAN
`
`pol
`
`Oct
`
`MAAWAS
`
`
`
`Page 3 of 15
`
`NVTLSSHTRUMVIOld
`
`ATION
`
`HOM
`
`
`tong—4----~4
`
`---=—4------4-----—@---+----wooee--.NOLWLYOOTNOILVOOT
`
`zat
`
`Page 3 of 15
`
`
`
`

`

`U.S. Patent
`U.S. Patent
`
`Jul. 2, 2013
`Jul. 2, 2013
`
`Sheet 2 of 5
`Sheet 2 of 5
`
`US 8,477,731 B2
`US 8,477,731 B2
`
`
`
`
`
`Page 4 of 15
`
`Page 4 of 15
`
`

`

`U.S. Patent
`
`Jul. 2, 2013
`
`Sheet 3 of 5
`
`US 8,477,731 B2
`
`YYTATHO
`
`WAAIFOSNVEL
`
`cot
`
`SSATHMIM
`
`ISSUamNYT
`
`YOOTA
`
`CcOld
`
`YOSsSAIOUd
`
`Li?
`
`O1T
`
`AYOWAWN
`
`AVTdSIG
`
`Page 5 of 15
`
`Page 5 of 15
`
`
`
`
`

`

`U.S. Patent
`
`Jul. 2, 2013
`
`Sheet 4 of 5
`
`US 8,477,731 B2
`
`302
`
`MOBILE DEVICE CONNECTS TO
`WIRELESS LAN
`
`304
`
`USER INITIATES A
`FINGERPRINT CAPTURE
`
`
`
`DEVICE MEASURES
`ATTRIBUTES OF FINGERPRINT
`
`306
`
`3O8
`
`DEVICE STORES INFORMATION
`ABOUT FINGERPRINT AND
`WIRELESS LAN
`
`FIG 3A
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`320
`
`CAPTURE A CURRENT FINGERPRINT
`Xl... Xn yl-..yn
`
`FOREACH BSS ID PERFORM THE
`FOLLOWING TEST
`x - Si () < d()
`ly - Pi () < q(-)
`FOR i = 1... In
`
`
`
`OPTIONALLY TEST
`XEx - Si () < X
`XEly - Pi () < Y
`
`SEARCHFORBSS ID
`
`FIG. 3B
`
`Page 6 of 15
`
`

`

`U.S. Patent
`
`Jul. 2, 2013
`
`Sheet 5 of 5
`
`US 8,477,731 B2
`
`
`
`
`
`402
`
`CONNECT TO WIRELESS LAN
`
`A-04
`
`DETERMINE IF BSSID EXISTS
`
`
`
`ADD ENTRY OF
`NEW FINGERPRINT
`
`408
`
`4()
`
`REFINE DEVIATION
`
`FIG. 4
`
`Page 7 of 15
`
`

`

`US 8,477,731 B2
`
`1.
`METHOD AND APPARATUS FOR LOCATING
`A WIRELESS LOCAL AREANETWORK INA
`WIDE AREANETWORK
`
`CLAIM OF PRIORITY UNDER 35 U.S.C. S 119
`The present application for patent claims priority to Provi
`sional Application No. 60/702,591 entitled, “ASSISTED
`WIRELESS NETWORK ACCESS POINT SEARCH IN
`WIRELESS COMMUNICATION NETWORKS, filed Jul.
`25, 2005, and Provisional Application No. 60/750,920
`entitled, “METHOD AND APPARATUS FOR LOCATING
`A WIRELESS LOCAL AREA NETWORK IN A WIDE
`AREA NETWORK filed Dec. 16, 2005, and Provisional
`Application No. 60/750,919 entitled, “METHOD AND
`15
`APPARATUS FOR MAINTAINING A FINGERPRINT
`FOR AWIRELESS NETWORK, filed Dec. 16, 2005, and
`assigned to the assignee hereof and hereby expressly incor
`porated by reference herein.
`
`10
`
`BACKGROUND
`
`30
`
`40
`
`1. Field
`The present disclosure relates generally to telecommuni
`cations, and more particularly, to systems and methods to
`25
`Support a mobile communications device capable of commu
`nicating via two different types of communication networks.
`2. Background
`The demand for wireless information services has led to
`the development of an ever increasing number of wireless
`networks. CDMA2000 1x is just one example of a wireless
`network that provides wide area telephony and data services.
`CDMA2000 1x is a wireless standard promulgated by the
`Third Generation Partnership Project 2 (3GPP2) using code
`division multiple access (CDMA) technology. CDMA is a
`35
`technology that allows multiple users to share a common
`communications medium using spread-spectrum processing.
`A competing wireless network that is commonly employed in
`Europe is Global System for Mobile Communications
`(GSM). Unlike CDMA2000 1x, GSM uses narrowband time
`division multiple access (TDMA) to support wireless tele
`phony and data services. Some other wireless networks
`include General Packet Radio Service (GPRS) which Sup
`ports high speed data services with data rates Suitable for
`e-mail and web browsing applications, and Universal Mobile
`Telecommunications System (UMTS) which can deliver
`broadband Voice and data for audio and video applications.
`These wireless networks can generally be thought of as
`wide area networks employing cellular technology. Cellular
`technology is based on a topology in which the geographic
`coverage region is broken up into cells. Within each of these
`cells is a fixed base transceiver station (BTS) that communi
`cates with mobile users. A base station controller (BSC) is
`typically employed in the geographic coverage region to con
`trol the BTSs and route communications to the appropriate
`gateways for the various packet-switched and circuit
`switched networks.
`As the demand for wireless information services continue
`to increase, mobile devices are evolving to support integrated
`Voice, data, and streaming media while providing seamless
`network coverage between wide area wireless networks
`(WANs) and wireless local area networks (LAN). Wireless
`LANs generally provide telephony and data services over
`relatively small geographic regions using a standard protocol,
`such as IEEE 802.11, Bluetooth, or the like. The existence of 65
`wireless LANs provides a unique opportunity to increase user
`capacity in a wide area wireless network by extending wide
`
`45
`
`50
`
`55
`
`60
`
`2
`area communications to the unlicensed spectrum using the
`infrastructure of the wireless LAN.
`Recently, various techniques have been employed to
`enable mobile devices to communicate with different wire
`less networks. Additional techniques have been employed to
`allow a mobile device to search for the presence of a wireless
`LAN to determine if one is available to connect to. However,
`frequent or continuous searching for a wireless LAN unnec
`essarily consumes power and can quickly discharge batteries
`in the mobile device. Accordingly, improvements in power
`consumption and battery life for mobile devices may be real
`ized by intelligently searching for available wireless LANs.
`
`SUMMARY
`
`One aspect of a wireless communications device is dis
`closed. The wireless communications device includes
`memory configured to store information relating to a first
`communications network, and a processor configured to
`determine whether the wireless communications device is in
`the vicinity of the first communications network based on the
`information stored in the memory and one or more reference
`signals from a second communications network.
`Another aspect of a wireless communications device is
`disclosed. The communications device includes memory
`configured to store information relating to a plurality of wire
`less LANs dispersed through a WAN, and a processor con
`figured to determine whether the wireless communications
`device is in the vicinity of one of the wireless LANs based on
`the information stored in the memory and one or more refer
`ence signals from the WAN.
`Computer readable media embodying a program of
`instructions executable by a computer to perform a method of
`communications is disclosed. The method includes accessing
`information in memory, the information relating to a first
`communications network, receiving one or more reference
`signals from a second communications network, and deter
`mining whether a wireless communications device is in the
`vicinity of the first communications network based on the
`information accessed from the memory and the one or more
`reference signals from the second communications network.
`A method of communications is disclosed. The method
`including accessing information in memory, the information
`relating to a first communications network, receiving one or
`more reference signals from a second communications net
`work, and determining whether a wireless communications
`device is in the vicinity of the first communications network
`based on the information accessed from the memory and the
`one or more reference signals from the second communica
`tions network.
`A further aspect of a wireless communications device is
`disclosed. The wireless communications device includes
`means for storing information relating to a first communica
`tions network, and means for determining whether the wire
`less communications device is in the vicinity of the first
`communications network based on the information and one
`or more reference signals from a second communications
`network.
`It is understood that other embodiments of the present
`disclosure are within scope of the following detailed descrip
`tion, wherein it is shown and described only various embodi
`ments of the disclosure by way of illustration. As will be
`realized, the disclosure is capable of other and different
`embodiments and its several details are capable of modifica
`tion in various other respects, all without departing from the
`spirit and scope of the present disclosure. Accordingly, the
`
`Page 8 of 15
`
`

`

`US 8,477,731 B2
`
`3
`drawings and detailed description are to be regarded as illus
`trative in nature and not as restrictive.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Various aspects of a wireless communications system are
`illustrated by way of example, and not by way of limitation, in
`the accompanying drawings, wherein:
`FIG. 1A is a conceptual block diagram of an embodiment
`of a wireless communications system;
`FIG. 1B is a conceptual block diagram of another embodi
`ment of a wireless communications system;
`FIG. 2 is a functional block diagram illustrating an
`example of a mobile device capable of supporting both wide
`area wireless and wireless LAN communications; and
`FIG. 3A depicts a flowchart of an exemplary method to
`create fingerprints on a mobile communications device;
`FIG. 3B depicts a flowchart of an exemplary method to
`compare fingerprints of different locations; and
`FIG. 4 depicts a flowchart of an exemplary method to refine
`an existing fingerprint for a known location.
`
`10
`
`15
`
`DETAILED DESCRIPTION
`
`4
`BTSs to extend the geographic reach of the WAN 104. When
`multiple BSCs are employed throughout the WAN 104, the
`MSC 110 may also be used to coordinate communications
`between the BSCs.
`The WAN 104 may also include one or more wireless
`LANs dispersed throughout the wide area wireless coverage
`region. A single wireless LAN 114 is shown in FIG. 1. The
`wireless LAN 114 may be an IEEE 802.11 network, or any
`other suitable network. The wireless LAN 114 includes an
`access point 116 for the mobile device 102 to communicate
`with an IP network 118. A server 120 may be used to interface
`the IP network 118 to the MSC 110, which provides a gateway
`to the PSTN 112.
`When power is initially applied to the mobile device 102, it
`will attempt to access either the WAN 104 or the wireless
`LAN 114. The decision to access a particular network may
`depend on a variety of factors relating to the specific appli
`cation and overall design constraints. By way of example, the
`mobile device 102 may be configured to access the wireless
`LAN 114 when the service quality meets a minimum thresh
`old. To the extent the wireless LAN114 can be used to support
`mobile telephony and data communications, valuable band
`width may be freed up for other mobile users.
`The mobile device 102 may be configured to continuously
`or periodically search for a beacon from the access point 116,
`or any other access point of a wireless LAN. The beacon is a
`periodic signal transmitted by the access point 116 with Syn
`chronization information. WLAN beacon search requires the
`mobile device to in turn tune to possible WLAN channels, in
`one or more operable bands of a WLAN system, and conduct
`either an active scan or a passive scan on the channel. In a
`passive scan the mobile device just tunes to the channel and
`receives for a specific period of time waiting for a beacon
`transmission. In an active Scan, the mobile device tunes to the
`channel and transmits a probe request after following the
`access procedures to avoid colliding with existing devices on
`the channel. On receipt of the probe request the access point
`transmits a probe response to the mobile device. In the event
`that the mobile device 102 cannot detect a beacon or receives
`no probe response to a probe request, which might be the case
`if power is applied to the mobile device 102 at location A, then
`the mobile device 102 attempts to access the WAN 104. With
`respect to FIG. 1B, described later, the mobile device 102
`does not continuously (or periodically) scan for a WLAN
`access point but, instead, scans for a WLAN access point only
`when it determines it is close to the wireless LAN 114. The
`mobile device 102 may access the WAN 104 by acquiring a
`pilot signal from the BTS 108. Once the pilot signal is
`acquired, a radio connection may be established between the
`mobile device 102 and the BTS 108 by means well known in
`the art. The mobile device 102 may use the radio connection
`with the BTS 108 to register with the MSC 110. Registration
`is the process by which the mobile device 102 makes its
`whereabouts known to the WAN 104. When the registration
`process is complete, the mobile device 102 may enter into an
`idle state until a call is initiated, either by the mobile device
`102 or the PSTN 112. Either way, an air traffic link may be
`established between the mobile device 102 and the BTS 108
`to set up and Support the call.
`When the mobile device 102 moves through the WAN 104
`from location A to location B in the depicted embodiment, it
`is now able to detect a beacon from the access point 116. Once
`this occurs, a radio connection may be established between
`the two by means well known in the art. The mobile device
`102 then obtains the IP address of the server 120. The mobile
`device 102 may use the services of a Domain Name Server
`(DNS) to determine the server's IP address. The domain name
`
`25
`
`30
`
`35
`
`45
`
`The detailed description set forth below in connection with
`the appended drawings is intended as a description of various
`embodiments of the disclosure and is not intended to repre
`sent the only embodiments in which the disclosure may be
`practiced. The detailed description includes specific details
`for the purpose of providing a thorough understanding of the
`disclosure. In some instances, well known structures and
`components are shown in block diagram form in order to
`avoid obscuring the concepts of the disclosure.
`In the following detailed description, various techniques
`will be described in connection with the handoff of a mobile
`user from one network to another. A number of these tech
`niques will be described in the context of a mobile commu
`nications device traveling through a wide area WAN with one
`or more wireless LANs dispersed throughout the WAN cov
`erage region. The mobile communications device may be any
`40
`suitable device capable of wireless telephony or data commu
`nications, such as a cellular phone designed for operation in a
`CDMA2000 1X network. The mobile communications device
`may be capable of employing any Suitable protocol for
`accessing a wireless LAN, including, by way of example,
`IEEE 802.11. While these techniques may be described in the
`context of a WAN phone capable of communicating with an
`IEEE 802.11 network, these techniques can be extended to
`other mobile communication devices capable of accessing
`multiple networks. For instance, these techniques may be
`applied to a mobile communications device capable of
`switching between a CDMA2000 1x network and a GSM
`network. Accordingly, any reference to a cellular phone
`capable of communicating with an IEEE 802.11 network, or
`any other specific embodiment, is intended only to illustrate
`various aspects of the present disclosure, with the understand
`ing that these aspects have a wide range of applications.
`FIG. 1A is a conceptual block diagram of an embodiment
`of a wireless communications system. A mobile device 102 is
`shown moving through a WAN 104 by a series of broken
`lines. The WAN 104 includes a BSC 106 supporting a number
`of BTSs dispersed throughout the WAN coverage region. A
`single BTS 108 is shown in FIG. 1 for simplicity of explana
`tion. A mobile switching center (MSC) 110 may be used to
`provide a gateway to a public Switched telephone network
`(PSTN) 112. Although not shown in FIG. 1, the WAN 104
`may employ numerous BSCs each Supporting any number of
`
`50
`
`55
`
`60
`
`65
`
`Page 9 of 15
`
`

`

`US 8,477,731 B2
`
`5
`of the server 120 may be delivered to the mobile device 102
`over the WAN 104. With the IP address, the mobile device 102
`can establish a network connection with the server 120. Once
`the network connection is established, information from the
`server 120 can be used in conjunction with local measure
`ments to determine whether the service quality of the wireless
`LAN 114 is sufficient to handoff the mobile device 102 to the
`access point 116.
`It should be noted, that while FIG. 1A is generally descrip
`tive of a cellular WAN, other WANs may be utilized. This may
`include those that do not utilize MSCs or other cellular struc
`tures, and those WANs utilizing other communication proto
`cols including wideband CDMA (WCDMA), TD-CDMA,
`GSM, or the like.
`Referring now to FIG. 1B, the wireless LAN 114 and BTS
`108 are shown in the context of a larger WAN having multiple
`BTS 122,124,126 and also multiple wireless LANs 129, 131
`and associated access points 128, 130. As shown in FIG. 1B,
`the mobile device 102 is not within the coverage area of any
`wireless LAN. Accordingly, searching for a beacon signal
`while in this location will prove fruitless and unnecessarily
`consume power. Even though the mobile device may fre
`quently enter a sleep or idle mode to conserve power, search
`ing for wireless LAN beacon signals can quickly consume
`power. In a typical 802.11 network configuration, the beacon
`signals occur at intervals measured in tens of milliseconds;
`thus, the mobile device must remain awake and searching for
`at least that period of time per channel and considering that
`the wireless LAN access point may be configured for differ
`ent frequency ranges and channels within those ranges, the
`mobile device 102 must remain awake a significant amount of
`time to search for available wireless LAN access points.
`Similarly, in the case of an active Scan, the mobile device must
`stay awake to follow the channel access procedures on the
`channel, then transmit a probe request and stay awake to
`receive a probe response. It must conduct this procedure on
`each channel. In this case as well, the mobile device 102 must
`remain awake a significant amount of time to search for
`available wireless LAN access points, which may result in
`increased power consumption and processing overhead.
`However, by limiting searching for beacon signals to peri
`ods when the mobile device is within the area 140, a signifi
`cant savings in power consumption may be realized. Thus,
`when the mobile device 102 periodically awakes to listen to
`the paging channel or a quick paging channel in the WAN it
`may also determine its location. If it determines that its loca
`tion is within the area 140, then it can search for a wireless
`LAN beacon signal. Otherwise, it can avoid unnecessarily
`searching for the beacon signal.
`A mobile device 102 may monitor beacon and pilot signals
`from the base stations of the WAN. These signals can include
`pilot and paging signals. The mobile device monitors these
`signals to measure primary and neighbor signal strengths to
`perform hand-offs between base stations. Also, in networks
`where the base stations are synchronized, the mobile device
`may also measure a phase of each pilot signal to assist with
`hand-off determination. Thus, at any location within the net
`work 104, the mobile device 102 observes up to n base sta
`tions with measurable signal strengths which can be charac
`terized as two vectors X, ..., X, and y, ...,y. Where each
`X value is a signal strength of a pilot signal from a base station
`and each y value is a phase of the pilot signal from a base
`station. When there are fewer than n observed signals, the
`remaining values are set to null. Because the pilot signals
`have a pilot phase offset associated with them, the signal
`strengths and phases may be easily identified as originating
`from aparticular base station. In other WAN technologies like
`
`40
`
`45
`
`6
`GSM, the neighbors base stations may be identified by their
`frequency channel or other base station identifier and a signal
`strength associated with each base station. In certain aspects,
`any signal utilized for acquisition, timing, or the like may be
`utilized as the signal that is utilized to obtain the measure
`ments to form the one or more vectors described above.
`Further, the vectors need not beformed, stored, or utilized as
`two vectors as described, or include the information in the
`format described above. Thus, in Some aspects, information
`that identifies a source and at least one characteristic of the
`reference signal, e.g. pilot or paging signal, is utilized.
`As is known in the art, the mobile device 102 monitors
`beacon and pilot signals from the base stations of the cellular
`network. These signals can include pilot and paging signals.
`The mobile device monitors these signals to measure primary
`and neighbor signal strengths to perform hand-offs between
`base stations. Also, in networks where the base stations are
`synchronized, the mobile device may also measure a phase of
`each pilot signal to assist with hand-off determination. Thus,
`at any location within the network 104, the mobile device 102
`observes up to n base stations with measurable signal
`strengths which can be characterized as two vectors X. . . . .
`X, and y. . . . . y. Where each X value is a signal strength of
`a pilot signal from a base station and each y value is a phase
`of the pilot signal from a base station. When there are fewer
`than n observed signals, the remaining values are set to null.
`Because the pilot signals have a pilot phase offset associated
`with them, the signal strengths and phases may be easily
`identified as originating from a particular base station. In
`other WAN technologies like GSM, the neighbors base sta
`tions may be identified by their frequency channel or other
`base station identifier and a signal strength associated with
`each base station.
`In WCDMA, base stations may not be synchronized. As in
`CDMA, when the mobile camps in the idle state on the paging
`channel of a particular base station, it scans for neighbor base
`station signals. In the case of CDMA each base station uses
`offsets of the same pseudo-random spreading sequence. In
`the case of WCDMA, each base station transmits a number of
`signals designed to allow the mobile station to rapidly acquire
`synchronization with the signals transmitted by that base
`station and once synchronized determine the spreading code
`group and spreading code in use by that base station. The set
`of spreading codes and their signal strengths may be used to
`create the fingerprint to identify a location in WCDMA cov
`erage corresponding to pilot offsets and pilot signal strengths
`in the CDMA system. Relative timing offsets of neighbor
`base stations may also be used corresponding to pilot phases
`in CDMA, however, if the base stations are not synchronized,
`their clocks may have relative drift making the timing offset
`an unreliable indicator.
`The information may be utilized as a conceptual finger
`print, or a signature, of a location of the mobile device 102.
`Thus, if locations within the area 140 have a certain known
`fingerprint, then the mobile device can determine its current
`fingerprint and compare it to the known fingerprint to deter
`mine whether the mobile device is located within the area
`140. While the above discussion merely mentions using two
`attributes of the WAN (i.e., pilot signal strength and phases).
`Further, as discussed above, other dynamic attributes of the
`WAN may be used instead of, or in combination with, these
`two attributes. For example, pilot offset values may be used as
`a fingerprint; even the number of pilot signals available is a
`possible attribute to be used for a fingerprint. Furthermore,
`the attributes that make up the fingerprint do not necessarily
`have to be attributes of the WAN. For example, many mobile
`devices have GPS receivers that can be used to determine the
`
`10
`
`15
`
`25
`
`30
`
`35
`
`50
`
`55
`
`60
`
`65
`
`Page 10 of 15
`
`

`

`US 8,477,731 B2
`
`10
`
`15
`
`40
`
`45
`
`7
`location of the mobile device relative to a wireless LAN. The
`GPS information may be used directly or even indirectly. As
`one example of the latter case, a base station ID along with
`phase measurements of GPS signals from different satellites
`may be used to define a fingerprint that corresponds to a
`location of the mobile device. Thus, in its broadest sense, a
`fingerprint is a collection of attributes of a first communica
`tion network that change based on location and can be used by
`the mobile device to determine the proximity of a second
`communication network. In addition, the fingerprint can also
`include characteristics of the transmitters of the second com
`munication networks (e.g. MAC ID, Band, Channel, RSSI
`information of the WiFi access points). In Such an instance,
`the WAN parameters may be thought of as trigger parameters
`Such that a match of the parameters triggers a WLAN search.
`The WLAN parameters can be used during the search as the
`search parameters for the triggered search.
`The attributes may be calculated in a variety of different
`ways without departing from the scope of the present disclo
`Sure. For example, an instantaneous measurement may be
`taken of such attributes as pilot signal strength and phase and
`used as the fingerprint. However, even when the mobile
`device is stationary, the values of these attributes vary because
`of environmental variability. Accordingly, multiple measure
`25
`ments may be taken and averaged together or otherwise com
`bined in some statistically significant manner in order to
`generate the fingerprint.
`FIG. 2 is a functional block diagram illustrating an
`example of a mobile device capable of supporting both WAN
`30
`and wireless LAN communications. The mobile device 102
`may include a WAN transceiver 202 and a wireless LAN
`transceiver 204. In at least one embodiment of the mobile
`device 102, the WAN transceiver 202 is capable of supporting
`CDMA2000 1x, WCDMA, GSM, TD-CDMA, or other WAN
`35
`communications with a BTS (not shown), and the wireless
`LAN transceiver 204 is capable of supporting IEEE 802.11
`communications with an access point (not shown). It should
`be noted, that the concepts described in connection with the
`mobile device 102 can be extended to other WAN and wire
`less LAN technologies. Each transceiver 202, 204 is shown
`with a separate antenna 206, 207, respectively, but the trans
`ceivers 202, 204 could share a single broadband antenna.
`Each antenna 206, 207 may be implemented with one or more
`radiating elements.
`The mobile device 102 is also shown with a processor 208
`coupled to both transceivers 202, 204, however, a separate
`processor may be used for each transceiver in alternative
`embodiments of the mobile device 102. The processor 208
`may be implemented as hardware, firmware, Software, or any
`combination thereof. By way of example, the processor 208
`may include a microprocessor (not shown). The microproces
`Sor may be used to support Software applications that, among
`other things, (1) control and