Abstract:
A database provides base station almanac information pertaining to more than one network mode of communication. A wireless device accesses this database through a centralized server or network, or via the base station, base station controller or the like, with which it is currently communicating.

Description:
RELATED APPLICATIONS 
     This application is a Divisional of U.S. patent application Ser. No. 12/625,343, filed Nov. 24, 2009, entitled “Base Station Almanac Assisted Positioning,” which is a Divisional of U.S. patent application Ser. No. 11/332,116, granted as U.S. Pat. No. 7,821,449, filed Jan. 12, 2006, entitled “Base Station Almanac Assisted Positioning,” which claims the benefit of U.S. Provisional Application No. 60/643,562, filed on Jan. 12, 2005, each of which is hereby incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The present method and apparatus relates generally to positioning systems for wireless user equipment, and more specifically to an almanac that contains the base station database for all or select set of base stations of a specific type. 
     BACKGROUND 
     Location determination systems allow wireless devices to find their geographic location or be located by remote entities by using satellites (e.g., GLONASS, GPS, Galileo, EGNOS, Globalstar, IRIDIUM) and/or base stations (e.g., cellular telephone base station, a wireless local area network, a wireless wide area network, satellite phone, satellite Internet, or any other device that can be uniquely recognized and communicate with the wireless device). These stations may be coupled to a base station almanac processor by way of a wide area network (WAN), but may also or alternatively use a local area network (LAN). The base station almanac processor accesses a base station database to tailor or customize an almanac according to the estimated location of the wireless device. 
     The wireless device can communicate with any number of devices to provide location information. The wireless device may be, for example, a cellular telephone that may have any number or combination of communication modes (e.g., GSM, CDMA, TDMA, WCDMA, OFDM, GPRS, EV-DO, WiFi, Bluetooth, WiMAX, 802.xx, UWB, satellite, etc.) to transfer voice and/or data with cellular, satellite, wireless data, and/or mesh networks by way of their base stations. The wireless device could also be a tracking device, a child or parolee monitor, navigational device, wireless pager, wireless computer, PDA, asset tag, etc. 
     SUMMARY 
     The method and apparatus disclosed herein provides an almanac that may contain the base station database for all or select set of base stations of a specific type (e.g., CDMA or WiFi or Bluetooth base stations). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is described in conjunction with the appended FIGURE. 
         FIG. 1  is a diagram of an embodiment of a wireless communication system. 
     
    
    
     DESCRIPTION 
     With the proliferation of multi-mode devices, the base station almanac for one particular mode of operation is not sufficient. If a target device can operate in more than one mode (e.g., CDMA and WiFi) for radio-location and communication purposes the device needs to know the almanac for both types of the base stations to operate properly. One feature of interest is the ability to seamlessly roam between the base stations of the same type or be handed over to a base station of a different type. 
     Referring to  FIG. 1 , either a centralized or a localized base station database  160  can be maintained for the base stations of the supported and relevant modes of communication (for example, may not be interested in the OMEGA base stations). 
     The supported communication modes for each wireless device  130  can be stored in a device capability database  163  that includes information to help in determining an uncertainty factor for each location or distance measurement made by a particular wireless device operating in any number of communication modes. 
     The almanac processor  162  may be separate from the base stations  150  (as shown), but each base station  150  or a group of base stations  150  could have a base station almanac processor  162  and/or databases in other embodiments. Alternatively, the almanac processor  162  can be integrated into the wireless device  130 . The base station database  160  and/or device capability database  163  could also be in the wireless device  130  and updated periodically. 
     In some embodiments, the base station database  160  may be centrally located (as illustrated in  FIG. 1 ), in others the base station database  160  may be distributed regionally or in portions relevant to each base station  150  or a group of base stations  150  as a local almanac. For example, a first base station  150 - 1 , may store a portion of the base station database for its footprint and all adjacent base station footprints in a first local almanac  164 . In another example, the first almanac may not be geographically organized but contain the base stations which are part of a particular service provider network. As the centrally-located base station database  160  is updated, those changes are propagated to the various local almanacs that might use the new information. 
     A target device  130  having access to the relevant base station almanac will be able to determine the location information given the knowledge of the communication mode and the identification of the base station  150  or a group of base stations  150  in the communication with the target device  130 . The location determination can be performed either by the target device  130  or with the target-device assistance. In the target device-assisted mode, the device  130  provides the information sufficient for the location determination by the external entity. 
     To further improve the search of the base station almanacs for the appropriate information, the data can be organized utilizing the hierarchical coverage scheme. For a particular region, for example, the Bay Area, or area identified by SID/NID, the number of CDMA and GSM switches can be listed. Under each switch a number of GSM and CDMA base station controllers can be listed. For each base station controller a number of base stations are provided, for each base station a number of sectors (typically from 1 to 6). For each sector, the base station almanac can contain the number of know WiFi base stations (access points  110 ) located within the coverage of the particular sector. The same can be done for other local area base stations such as Bluetooth, UWB, ZigBee, RFID, etc. This classification can be extended to show cross references whereby some of the local area base stations can be within the signal coverage of the other local are base stations providing further granularity to the location information. For example, a number of Bluetooth base stations can be within coverage of a particular WiFi access point  110 . 
     Each “computer”, “base station”, “base station controller”, “server”, or other network infrastructure, “wireless device”, “mobile station”, or “user equipment”, referred to herein includes the necessary “computer-readable” media to perform the functions described herein, or is in communication with the necessary computer-readable media. The term “computer-readable medium” refers to any medium that participates in providing instructions to a processor for execution. The singular “medium” is defined herein to include the plural “media”. 
     “Computer readable media” may take many forms, including but not limited to, “non-volatile media”, “volatile media”, and “transmission media”. “Non-volatile media” includes, for example, optical or magnetic disks such as used for a storage medium. “Volatile media” includes dynamic memory. Common forms of “computer-readable media” include floppy disks, flexible disks, hard disks, magnetic tape, other magnetic mediums, CD-ROM or other optical medium, RAM, PROM, EPROM, FLASH EPROM, and other memory chips or cartridges, a carrier wave, or any medium from which a computer or processor, as those terms are known to those skilled in the art, can read. Databases, data, and/or records can be recorded or stored on computer readable media. The term “data” as used herein refers to information. 
     It will be understood as used herein that a processor or microprocessor can, but need not necessarily include, one or more microprocessors, embedded processors, controllers, application specific integrated circuits (ASICs), digital signal processors (DSPs), and the like. The terms processor and microprocessor are intended to describe hardware implementing the functions described rather than specific hardware. As used herein the term “memory” refers to any type of long term, short term, or other memory associated with the computer or other described device, and is not to be limited to any particular type of memory or number of memories, or type of media upon which memory is stored.