Abstract:
A dual-mode mobile station for accessing a wide-area wireless network according to a first wireless protocol and a small-area wireless network according to a second wireless protocol. The dual-mode mobile station comprises a controller that switches the dual-mode mobile station between a first mode in which the dual-mode mobile station communicates with the wide-area wireless network and a second mode in which the dual-mode mobile station communicates with the small-area wireless network. The controller switches the dual-mode mobile station between the first and second modes depending on a distance between the dual-mode mobile station and an access point of the small-area wireless network. When the dual-mode transceiver enters the first mode, the controller turns off a transceiver that operates in the second mode in order to save power.

Description:
CROSS-REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY  
       [0001]     The present invention is related to that disclosed in U.S. Provisional Patent No. 60/611,602, filed Sep. 21, 2004, entitled “Dual-Mode Phone Using GPS Assist To Switch Between Cellular and Wi-Fi Modes”. U.S. Provisional Patent No. 60/611,602 is assigned to the assignee of the present application. The subject matter disclosed in U.S. Provisional Patent No. 60/611,602 is hereby incorporated by reference into the present disclosure as if fully set forth herein. The present application hereby claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent No. 60/611,602.  
     
    
     TECHNICAL FIELD OF THE INVENTION  
       [0002]     The present invention is directed generally to a dual-mode phone that uses a GPS unit to switch between cellular operation and WiFi operation and to switch off power to the WiFi transceiver.  
       BACKGROUND OF THE INVENTION  
       [0003]     Wireless service providers continually seek new ways to improve wireless service (e.g., cellular service) and to maximize the capabilities of the current wireless infrastructure. There is a growing movement to integrate the capabilities of conventional wide-area cellular networks (e.g., CDMA, GSM, TDMA) and small area wireless or WiFi networks (e.g., IEEE-802.11a/b/g) in order to provide “One-Phone” service to users. One-Phone service allows the user of a conventional mobile station (e.g., cell phone, wireless PC or PDA) to use voice-over-IP (VoIP) service over a wireless broadband connection when the user is at home, at the office, or in a wireless hotspot and use the wide-area cellular (i.e., macro-cellular) service when the user is away from home, the office, or the wireless hotspot. In the most common approach, the wireless connection for the VoIP-over-broadband service is provided by a WiFi (IEEE-802.11a/b/g) connection.  
         [0004]     This trend is driven primarily by two factors. The first factor is the dramatically lowered cost of providing VoIP telephony service over a wired infrastructure. The second factor is the demand to have a single phone identity without making a distinction between a home phone number and a cell phone number.  
         [0005]     In order to provide a good user experience, One-Phone service must seamlessly migrate from a WiFi network to a cellular network, especially when the user is in an active call. The migration from the cellular network to the WiFi network is generally not an issue during an active call, since the user may continue to use the cellular connection even if the user is in range of the WiFi network (i.e., there is no reason to break the cellular connection).  
         [0006]     However, the IEEE-802.11 standard was not intended for portable telephony applications. The power requirements of IEEE-802.11x devices are quite large. When an IEEE-802.11 interface is used on a mobile station to offer dual-mode service, the battery life of the mobile station is greatly reduced. This may lead the user of the mobile station (e.g., cell phone) to believe that mobile stations from that manufacturer are of poor quality. The best way to combat the WiFi-induced battery drain is to turn off completely the WiFi interface when it is not in use and to turn the WiFi interface on only when the user manually enters a command when the user is near home, the office of another hot spot.  
         [0007]     Currently, there are no methods for reliably and automatically detecting when the WiFi interface should be turned on or turned off. Thus, manual control remains the only viable option. However, using manual control to enable and disable the WiFi mode defeats the purpose of achieving seamlessness between wide-area wireless (i.e., cellular) operation and small-area wireless (i.e., WiFi) operation.  
         [0008]     Thus, there is a need for a mobile station that can switch seamlessly between macro-cellular networks and Wi-Fi networks without adversely affecting battery life. In particular, there is a need for a mobile station that can reliably and automatically detect the presence of a WiFi network without adversely affecting battery life. There also is a need for a cell phone that can reliably detect the loss of the WiFi network connection when moving away from a WiFi access point (AP).  
       SUMMARY OF THE INVENTION  
       [0009]     Almost all current cell phones have a built-in GPS receiver in order to comply with the federal E 911  requirements. The present invention provides a mechanism for enabling and disabling the WiFi transceiver of a mobile station using the built-in GPS receiver of the mobile station, a built-in database of WiFi hotspot locations, and a software-based controller. Thus, the present invention provides a dual-mode cell phone (or similar mobile station) with the ability to switch from, for example, an IEEE-802.11a/b/g network to a CDMA cellular network without dropping an on-going voice-over-IP (VoIP) phone call. The GPS receiver consumes a relatively small amount of power. Thus, the present invention uses GPS information readily available in current mobile stations to reduce the power consumption of the IEEE-802.11 components of a dual-mode mobile station.  
         [0010]     To address the above-discussed deficiencies of the prior art, it is a primary object of the present invention to provide a dual-mode mobile station capable of accessing a wide-area wireless network according to a first wireless protocol and a small-area wireless network according to a second wireless protocol. According to an advantageous embodiment of the present invention, the dual-mode mobile station comprises a controller capable of switching the dual-mode mobile station between a first mode in which the dual-mode mobile station communicates with the wide-area wireless network and a second mode in which the dual-mode mobile station communicates with the small-area wireless network, wherein the controller switches the dual-mode mobile station between the first and second modes depending on a distance between the dual-mode mobile station and an access point of the small-area wireless network.  
         [0011]     According to one embodiment of the present invention, the dual-mode mobile station further comprises a location-determining apparatus capable of determining a location of the dual-mode mobile station.  
         [0012]     According to another embodiment of the present invention, the location-determining apparatus comprises a GPS receiver.  
         [0013]     According to still another embodiment of the present invention, the dual-mode mobile station further comprises a first transceiver capable of communicating with the wide-area wireless network.  
         [0014]     According to yet another embodiment of the present invention, the dual-mode mobile station further comprises a second transceiver capable of communicating with the small-area wireless network.  
         [0015]     According to a further embodiment of the present invention, the dual-mode mobile station further comprises a memory associated with the controller capable of storing a plurality of access point records, wherein each of the plurality of access point records comprises location information associated with an access point of the small-area wireless network.  
         [0016]     According to a still further embodiment of the present invention, the controller is capable of comparing a current position of the dual-mode mobile station to the location information in the each of the plurality of access point records in order to determine a distance between the dual-mode mobile station and each of the plurality of access points of the small-area wireless network.  
         [0017]     According to a yet further embodiment of the present invention, the controller switches the dual-mode mobile station from the first mode to the second mode when a first distance between the dual-mode mobile station and a first one of the plurality of access points of the small area wireless network is less than a predetermined threshold value.  
         [0018]     In one embodiment of the present invention, the controller causes the second transceiver to search for a beacon signal associated with the first access point when the dual-mode mobile station switches to the second mode.  
         [0019]     In another embodiment of the present invention, the controller switches the dual-mode mobile station from the second mode to the first mode when the first distance between the dual-mode mobile station and the first access point is greater than the predetermined threshold value.  
         [0020]     In still another embodiment of the present invention, the controller disables the second transceiver when the dual-mode mobile station switches to the first mode to thereby reduce a power consumption of the second transceiver.  
         [0021]     In yet another embodiment of the present invention, the dual-mode mobile station is capable of downloading the plurality of access point records from the wire-area wireless network.  
         [0022]     Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     For a more complete understanding of the present invention and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:  
         [0024]      FIG. 1  illustrates a dual-mode mobile station that is capable of switching between an access point of a WiFi network and a base station of a cellular network according to the principles of the present invention;  
         [0025]      FIG. 2  illustrates the dual-mode mobile station in  FIG. 1  in greater detail according to an exemplary embodiment of the present invention; and  
         [0026]      FIG. 3  illustrates in greater detail the WiFi hot spot database in the dual-mode mobile station in  FIG. 2  according to an exemplary embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]      FIGS. 1 through 3 , discussed herein, and the various embodiments used to describe the principles of the present invention in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the invention. Those skilled in the art will understand that the principles of the present invention may be implemented in any suitably arranged wireless mobile station.  
         [0028]      FIG. 1  illustrates dual-mode mobile station  110 , which is capable of switching between an access point of small-area (or local) wireless network and a base station of a cellular network or a similar wide-area wireless network according to the principles of the present invention. In the illustrated embodiment, mobile station  110  is capable of communicating with base stations  101 - 103  of a CDMA wireless network and with access points  121 - 123  of a WiFi (e.g., IEEE-802.11x) network. However, the choice of CDMA and WiFi is by way of example only and should not be construed to limit the scope of the present invention.  
         [0029]     In an alternate embodiment of the present invention, base stations  101 - 103  may operate under a protocol other than CDMA, such as GSM, for example. In an alternate embodiment of the present invention, access points  121 - 123  may operate under a protocol other than IEEE-802.11x. More broadly speaking, the present invention is not limited to use in cellular phones, but may be implemented in any dual-mode mobile station. This may include, for example, a laptop computer equipped with a WiFi transceiver, a GPS receiver, and a cellular (e.g., GSM, CDMA) transceiver.  
         [0030]     Base stations  101 - 103  are capable of communicating with an IP-based network, such as Internet  140 , via packet data server node (PDSN)  145 . Base stations  101 - 103  are also capable of communicating with public switched telephone network (PSTN)  150  via mobile switching center  155 . Base stations  101 - 103  use MSC  155  and PSTN  150  to provide conventional voice connections and telephony services between MS  110  and another telephone device. Base stations  101 - 103  use PDSN  145  and Internet  140  to provide packet data services, including voice-over-IP (VoIP) services, between MS  110  and another Internet protocol (IP) node. Similarly, WiFi access points  121 - 123  use Internet  140  to provide packet data services, including voice-over-IP (VoIP) services, between MS  110  and another Internet protocol (IP) node.  
         [0031]      FIG. 2  illustrates dual-mode mobile station  110  in greater detail according to an exemplary embodiment of the present invention. Mobile station (MS)  110  comprises CDMA transceiver (X-CVR)  210 , IEEE-802.11x transceiver (X-CVR)  220 , global positioning system (GPS) receiver  240 , and controller  230 . According to the principles of the present invention, it is assumed that any mobile station, such as MS  110 , that supports One-Phone service also possesses an embedded GPS receiver, such as GPS receiver  240 .  
         [0032]     Controller  230  further comprises processor  250  and memory  255 . Memory  255  may comprise both static memory (e.g., Flash RAM or ROM) and dynamic memory (i.e., DRAM). Memory  255  stores operating system (OS) program  260  and hot spot database (DB)  265 . As will be explained below in greater detail, hot spot database  265  contain geographical position information (i.e., GPS co-ordinates) of access points  121 - 123  and other WiFi access points.  
         [0033]     For the purposes of simplicity and clarity in explaining the operation of the present invention, it shall be assumed that access point (AP)  121  is located in the home of the user of mobile station (MS)  110 , that access point (AP)  122  is located in the office of the user of MS  110 , and that access point (AP)  123  is located at some other place (i.e., coffee shop) frequented by the user of MS  110 . It shall also be assumed that MS  110  is capable of communicating with base station (BS)  101  whenever MS  110  is in the vicinity of AP  121 , AP  122  or AP  123 .  
         [0034]      FIG. 3  illustrates WiFi hot spot database  265  in dual-mode mobile station  110  in greater detail according to an exemplary embodiment of the present invention. Hot spot database  265  comprises N access point records, including exemplary access point (AP) records  310 ,  320 ,  330  and  340 . AP record  310  comprises a first access point identifier field associated with a first access point (labeled AP  1 ) and a first location field, labeled GPS Coordinates 1, associated with AP  1 . AP record  320  comprises a second access point identifier field associated with a second access point (labeled AP  2 ) and a second location field, labeled GPS Coordinates 2, associated with AP  2 . AP record  330  comprises a third access point identifier field associated with a third access point (labeled AP  3 ) and a third location field, labeled GPS Coordinates 3, associated with AP  3 . Finally, AP record  340  comprises an N th  access point identifier field associated with an N th  access point (labeled AP N) and an N th  location field, labeled GPS Coordinates N, associated with AP N. By way of example, AP  1  may be AP  121 , AP  2  may be AP  122 , and AP  3  may be AP  123 .  
         [0035]     Each one of the access point identifier fields, AP  1 -AP N, comprises information that may be used to identify and access a particular access point, such as an electronic serial number (ESN), a user name and password, encryption information, or a combination of these values. When MS  110  is in the vicinity of an access point stored in hot spot database  265 , MS  110  uses the information in the access point identifier field to rapidly search for, and set up a connection to, that access point.  
         [0036]     When MS  110  is activated for the first time in the residence of the user of MS  110 , controller  230  receives from GPS receiver  240  the GPS location information of AP  121 . Controller  230  then stores this information in hot spot database  265 . Optionally, controller  230  may display information to the user of MS  110  and receive manual input commands from the user in order to select AP  121  as a known access point that will be associated with MS  110 . The binding of mobile station  110  to the GPS co-ordinates of AP  121  can be done in a variety of ways. It may be done manually when the user uses the WiFi service at home for the very first time. It also may be done via an SMS message sent from AP  121  over the broadband wire link and Internet  140  to MSC  155 , which is associated with base station  101 . In a similar manner, MS  110  receives and stores information for AP  122  the first time MS  110  is operated when the user of MS  110  is at work.  
         [0037]     According to the principles of the present invention, when mobile station  110  moves into the vicinity of AP  121 , controller  230  activates the WiFi interface by applying power to IEEE-802.11x transceiver  220 , which then scans for an IEEE-802.11 beacon from AP  121 . Controller  230  determines whether MS  110  is in the vicinity of an access point by periodically comparing the current GPS co-ordinates of MS  110  to the stored GPS coordinates of all of the access points stored in hot spot database  265 , including the stored GPS co-ordinates of AP  121 , AP  122 , and AP  123 . If the GPS co-ordinates of MS  110  is less than a predetermined threshold value away from the GPS coordinates of an access point, then MS  110  is in the vicinity of that access point.  
         [0038]     If MS  110  is currently in an active call over the cellular network via BS  101 , the call is not disturbed. As soon as controller  230  detects that MS  110  is near, for example, AP  121 , controller  230  performs the necessary IEEE-802.11x set-up (or access) procedures and subsequently registers MS  110  over the WiFi link and the broadband line with the cellular network. All subsequent calls are then placed via the WiFi network, rather than via BS  101 .  
         [0039]     Similarly, when MS  110  is active in the WiFi environment (via AP  121 , for example) and begins moving out of the WiFi environment (i.e., away from AP  121 ), controller  230  detects that MS  110  is moving out of the range of WiFi AP  121 . The detection is performed once again by comparing the current GPS co-ordinates of MS  110  to the GPS co-ordinates of AP  121  stored in hot spot database  265 . This out-of-range detection procedure may be augmented by other heuristics, such as decreased receive (RX) signal power, increased frame error rate, or the like.  
         [0040]     Subsequently, controller  230  places an identical call over the macro-cellular environment via CDMA transceiver  210  and instructs MSC  155  of the cellular network to switch the call from the VoIP service provided by AP  121  to the cellular voice or data service used by BS  101 . The switching of the call may be handled in a number of ways, including in the same manner as adding another participant to a conference call. As soon as the cellular connection is successfully established, the WiFi interface is terminated and IEEE-802.11x transceiver  220  is powered off.  
         [0041]     Controller  230  may employ additional heuristics to avoid ping-pong situations in which IEEE-802.11x transceiver  220  is turned off and on frequently (e.g., when a user goes to his backyard and then comes back indoors). By utilizing the GPS information coupled with pre-programmed information in OS program  265 , mobile station  110  may turn IEEE-802.11x transceiver  220  on and off in an optimal manner.  
         [0042]     Optionally, the cellular network operator that operates base stations  101 - 103  may distribute to MS  110  and other mobile stations a database of GPS co-ordinates of well-known hot spots (e.g., coffee shops) supported by the cellular network. A mobile stations with One-Phone service may look up hot spot database  265  in order to determine whether or not to use IEEE-802.11 transceiver  220 . Hot spot database  265  may be updated via emerging IP-based over-the-air (OTA) provisioning and updating techniques (e.g., CDG IOTA-PA, OMA/WAP provisioning, and the like). Thus, the embedded database serves as a PRL for VoIP calls.  
         [0043]     Advantageously, the present invention reduces the power consumption of handsets while hunting for IEEE-802.11 networks. By disabling IEEE-802.11 transceiver  220  when MS  110  is not near a known hot spot, the present invention greatly reduce the power consumption caused by IEEE-802.11 transceiver  220 . GPS receiver  240  is already present in many new mobile stations and has a much lower power draw than IEEE-802.11 transceiver  220 .  
         [0044]     Although the present invention has been described with an exemplary embodiment, various changes and modifications may be suggested to one skilled in the art. It is intended that the present invention encompass such changes and modifications as fall within the scope of the appended claims.