Abstract:
The invention relates to a method for operating a mobile communication device, the method comprising the steps of:  
     setting the mobile communication device into a discoverable mode,  
     entering a communication zone, the zone being delimited by at least one access point, the access point being adapted to discover the mobile communication device, when the mobile communication device is in the discoverable mode,  
     performing an inquiry scan in response to the entry into the communication zone in order to identify one or more other communication devices with which a communication link can be established.

Description:
[0001]    The invention is based on a priority application No. 02 360 094.3 which is hereby incorporated by reference.  
         FIELD OF THE INVENTION  
         [0002]    The present invention relates in general to the field of mobile communication and in particular, by way of example but not limitation, to portable battery-operated electronic devices, such as Bluetooth communication devices  
         BACKGROUND OF THE INVENTION  
         [0003]    Mobile communication devices are usually powered by small, rechargeable batteries that normally provide a limited number of hours of active service. A number of power saving techniques have been devised in the prior art with a goal to extend the number of hours of active service.  
           [0004]    U.S. Pat. No. 6,323,775 shows a method for proximity-based recharge notification. A user is notified of a low battery condition when the remaining battery capacity of a portable electronic device, such as a mobile station, pager, portable computer, video camera, or personal digital assistant, falls below a predetermined level and the portable electronic device is proximally located to a corresponding charging unit. The proximity of the portable electronic device to the charging unit may be detected by using geographic positioning, such as the GPS, the GLONASS or the GSM location-determining algorithms, or by monitoring a short range radio interface, such as Bluetooth or Home RF.  
           [0005]    Bluetooth is a protocol designed for short range communication. The Bluetooth protocol is described in Bluetooth specification, volumes 1 and 2, version 1.1, Feb. 22, 2001 available at www.bluetooth.com.  
           [0006]    A Bluetooth device can have a variety of modes. One of the modes is the inquiry mode where an inquiring Bluetooth device scans its environment in order to identify other Bluetooth devices.  
           [0007]    The “discoverability modes” constitute another category of modes. With respect to an inquiry, a Bluetooth device is either in a non-discoverable mode or in a discoverable mode. When a Bluetooth device is in a non-discoverable mode it does not response to inquiry.  
           [0008]    In the Bluetooth standard there are two different discoverable modes which are called “limited discoverable mode” and “general discoverable mode”.  
           [0009]    A Bluetooth device is said to be made discoverable, or set into a discoverable mode, when it is in limited discoverable mode or in general discoverable mode.  
           [0010]    The limited discoverable mode is used by devices that need to be discoverable only for a limited period of time, during temporary conditions or for a specific event. The purpose is to respond to a device that makes a limited inquiry. The scanning for the limited inquiry access code can be done either in parallel or in sequence with the scanning of the general inquiry access code.  
           [0011]    The general discoverable mode is be used by devices that need to be discoverable continuously or for no specific condition. The purpose is to respond to a device that makes a general inquiry.  
           [0012]    The default state of a Bluetooth communication device is passive, i.e. if the Bluetooth device needs to determine if Bluetooth services are available in its proximity it must first perform an inquiry scan of its environment to discover the inrange Bluetooth service points. This inquiry scan phase is necessary to retrieve the Bluetooth identifiers of these service points.  
           [0013]    One mode of operating such a Bluetooth communication device is to initiate an inquiry scan only upon a corresponding user request. The disadvantage of this approach is that a manual user input operation is required. Also the user will only be notified of available Bluetooth services when he or she requires to scan the environment but no automatic notification is possible.  
           [0014]    An alternative approach is to continuously put the Bluetooth device into the inquiry scan mode. The problem with this approach is that a Bluetooth device typically consumes about 45 times more power than in the standby discoverable mode.  
         SUMMARY OF THE INVENTION  
         [0015]    The present invention provides for a method of operating a mobile communication device, such as a Bluetooth device or another short range communication device, which enables to safe power and thus extend the battery lifetime. In brief the underlying idea of the invention is that an inquiry scan is only necessary if there are in fact service points within a zone surrounding the communication device; if it is not known that there are such service points within proximity a standby discoverable mode is sufficient. This approach enables to drastically reduce power consumption and still perform inquiry scans when they are needed.  
           [0016]    In accordance with a first preferred embodiment of the invention a communication zone is defined. The communication zone can be an area within a building, such as a shopping mall, or a commercial street. A number of Bluetooth service points are placed within that communication zone. At the entry and the exit of the communication zone Bluetooth access points are located which delimit the communication zone at the entry and/or access points of the zone.  
           [0017]    In accordance with a further preferred embodiment of the invention the Bluetooth service points and the Bluetooth access points of the communication zone are permanently in the inquiry mode. Typically the Bluetooth service and access points are fixed devices which are not battery operated such that the power consumption required in the inquiry scan mode does not constitute a shortcoming.  
           [0018]    When a Bluetooth mobile communication device is located outside the communication zone it is set into a discoverable mode as a default mode. In the discoverable mode the power consumption of the mobile communication device is minimal. When a user enters the communication zone with the mobile communication device this device is recognized by the corresponding Bluetooth access point as this access point permanently scans its environment for Bluetooth devices. When the Bluetooth access point detects the mobile communication device it sends a command to the mobile communication device. In response the mobile communication device performs an inquiry scan to identify other communication devices, in particular the Bluetooth service points and/or the Bluetooth access points, within its proximity.  
           [0019]    In accordance with a preferred embodiment of the invention the mobile communication device stays in the inquiry scan mode while it remains in the communication zone. Only when the user exits the communication zone the device is reset into the discoverable mode. The location of the mobile communication device within the communication zone can be determined by a position determination technique provided by the local positioning profile as defined in the Bluetooth specification.  
           [0020]    Alternatively or in addition timeout techniques can be utilized. In one implementation a timer is started when the user enters the communication zone. When the timer expires the mobile communication device is automatically reset into the discoverable mode. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    [0021]FIG. 1 is illustrative of a first embodiment of the method for operating a mobile communication device,  
         [0022]    [0022]FIG. 2 is illustrative of a second embodiment of the method for operating a mobile communication device,  
         [0023]    [0023]FIG. 3 is a block diagram of a preferred implementation of a mobile communication device,  
         [0024]    [0024]FIG. 4 is a block diagram of a preferred implementation of an access point,  
         [0025]    [0025]FIG. 5 shows a communication system of the invention with a communication zone. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    [0026]FIG. 1 is illustrative of a process  1  of a mobile terminal, such as a Bluetooth mobile communication device, and a process  2  of an access point within a communication zone.  
         [0027]    In step  3  the mobile terminal is set into the discoverable mode. This is the default mode for the mobile terminal.  
         [0028]    On the other hand the access points of the communication zone are set into the inquiry scan mode in step  4  of process  2 .  
         [0029]    When the mobile terminal is entered into the communication zone in step  5  this is discovered by one of the access points in step  6  of the process  2  as the access points permanently or at close time intervals scan the environment.  
         [0030]    In step  7  the access point which has discovered the mobile terminal in step  6  sends a command to the mobile terminal.  
         [0031]    This command is received by the mobile terminal in step  8 . In response the inquiry scan mode is set in the mobile terminal in step  9 . This way one or more other communication devices or Bluetooth services are identified in the proximity of the mobile terminal in step  10 . This enables the mobile terminal to use one or more Bluetooth applications in conjunction with the devices and/or services detected in step  10 . The corresponding application or applications are carried out in step  11 .  
         [0032]    In step  12  the mobile terminal exits the communication zone. This is discovered by one of the access points of the communication zone in step  13 . In step  14  a command is sent to the mobile terminal from the access point which has discovered the mobile terminal. The steps  13  and  14  are analogous to the steps  6  and  7 .  
         [0033]    The command is received by the mobile terminal in step  15 . In response the mobile terminal is reset into the discoverable mode in order to safe power.  
         [0034]    The discovery of the mobile terminal at the boundary of the communication zone in steps  6  and  13  can be done based on proximity, i.e. by means of the inquiry scan. Alternatively GPS-based techniques can be utilized in order to determine whether the mobile terminal is within the communication zone or not. As a further option the local positioning profile techniques devised in the Bluetooth specification can be employed.  
         [0035]    [0035]FIG. 2 shows an alternative approach for implementation of the processes  1  and  2  of FIG. 1. Again the mobile terminal is set into the discoverable mode in step  20  and the access points of the communication zone are in the inquiry scan mode in step  21 , as it is the case in the corresponding steps  3  and  4  of FIG. 1.  
         [0036]    When the mobile terminal is entered into the communication zone in step  22  this is discovered within the communication zone. For example the local positioning profile techniques or GPS-based techniques are utilized within the communication zone in order to determine that the mobile terminal has entered the communication zone.  
         [0037]    In step  24  a command is sent from one of the access points in the proximity of the mobile terminal. The mobile terminal receives this command in step  25  which starts a timer in step  26  and sets the inquiry mode in step  27 . The following steps  28  and  29  are analogous to the steps  10  and  11  of FIG. 1.  
         [0038]    In step  30  the timer which has been started in step  26  expires. In response the discoverable mode is reset in step  31 .  
         [0039]    [0039]FIG. 3 shows a block diagram of a mobile terminal  32 . The mobile terminal can be a Bluetooth mobile communication device. The mobile terminal  32  has a module  33  to operate the mobile terminal  32  in the discoverable mode. Further the mobile terminal  32  has a module  34  to operate the mobile terminal  32  in the inquiry scan mode.  
         [0040]    A module  35  serves to select the discoverable mode or the inquiry scan mode, i.e. the module  33  or  34 .  
         [0041]    Further the mobile terminal  32  has one or more modules  36  to run a variety of Bluetooth or other applications. Further the mobile terminal  32  has a wireless interface  38 . As an option the mobile terminal  32  has a timer  37 .  
         [0042]    In operation the module  33 , i.e. the discoverable mode, is selected by the module  35  as the default mode of operation. When the mobile terminal  32  is brought into a communication zone by a user a command is received from one of the access points of the communication zone by the wireless interface  38  (cf. steps  8  and  25  of FIGS. 1 and 2, respectively). In response the module  35  selects the module  34  in order to operate the mobile terminal  32  in the inquiry scan mode. By means of the inquiry scan mode other communication devices and/or services within the proximity of the mobile terminal  32  are detected such that one or more of the applications of module  36  are invoked.  
         [0043]    The mode of operation of the mobile terminal  32  is reset into the discoverable mode by the module  35  when the wireless interface  38  receives another command from an access point of the communication zone (cf. step  15  of FIG. 1). Alternatively the resetting of the mode is done based on timer  37 . In this instance the selection of the module  34  by the module  35  starts the timer  37 . When the timer  37  expires this is signalled to the module  35  which in response deselects module  34  and selects module  33 .  
         [0044]    [0044]FIG. 4 shows a block diagram of an access point of the communication zone. The access point  40  preferably is a fixed device which is connected to a power line. The access point  40  has a module  41  in order to operate the access point  40  in the inquiry scan mode. Further the access point  40  has a module  42  in order to generate the command to be sent to a mobile terminal entering the communication zone (cf. steps  7  and  14  of FIG. 1 and step  24  of FIG. 2). In order to perform the inquiry scan and to send the command the access point  40  has wireless interface  43 .  
         [0045]    As an option the access point  40  has a module  44  which serves to position a mobile terminal with respect to the communication zone. The module  44  can be based on the local positioning profile technique as devised in the Bluetooth specification or on another principle to determine the location of the mobile terminal, such as GPS.  
         [0046]    In operation the command is sent via the wireless interface  43  from the access point  40  when it is detected, that a mobile terminal enters the communication zone. This detection may be performed either based on the result of the inquiry scans performed by the access point  40  by means of its module  41  and/or by means of module  44 .  
         [0047]    [0047]FIG. 5 shows an application example for the present invention. A communication zone  50  is defined by a building  51 , such as a shopping mall or commercial street. The building  51  has an entrance  52  and an exit  53 . At the entrance  52  and at the exit  53  Bluetooth access points (AP)  54  and  55 , respectively, are located. The wireless interfaces of these access points  54  and  55  (cf. FIG. 4) have a certain reach R which delimits the communication zone at the entrance  52  and the exit  53 .  
         [0048]    Within the communication zone  50  there is a number of Bluetooth service points (BT)  56 .  
         [0049]    When a mobile terminal  32  (cf. FIG. 3) is outside the communication zone  50  at position A the mobile terminal  32  is in its discoverable mode. In this mode the mobile terminal  32  only consumes minimal power. When the mobile terminal  32  is brought into the communication zone  50  along path  57  this is detected by the access point  54  which sends a command to the mobile terminal  32  in order to put the mobile terminal  32  into its inquiry scan mode.  
         [0050]    In the inquiry scan mode the mobile terminal  32  recognizes one or more of the service points  56  within the communication zone  50 , such as when the mobile terminal  32  is at its position B along the path  57 .  
         [0051]    When the mobile terminal  32  exits the communication zone  50  this is also detected. In one implementation the access point  55  discovers that the mobile terminal  32  leaves the communication zone  50 . In response the access point  55  sends a command to the mobile terminal  32  in order to reset the discoverable mode. Alternatively the mobile terminal  32  is reset into the discoverable mode upon expiry of the timer (cf. timer  37  of FIG. 3).  
         [0052]    It is to be noted that the present invention is not only applicable with respect to Bluetooth enabled devices but that a variety of alternative communication protocols can be utilized for implementation of the invention. One example for such an alternative protocol is wireless LAN.  
       LIST OF REFERENCE NUMERALS  
       [0053]    process  1   
         [0054]    process  2   
         [0055]    mobile terminal  3   
         [0056]    module  33   
         [0057]    module  34   
         [0058]    module  35   
         [0059]    module  36   
         [0060]    timer  37   
         [0061]    wireless interface  38   
         [0062]    access point  40   
         [0063]    module  41   
         [0064]    module  42   
         [0065]    wireless interface  43   
         [0066]    module  44   
         [0067]    communication zone  50   
         [0068]    building  51   
         [0069]    entrance  52   
         [0070]    exit  53   
         [0071]    access points  54   
         [0072]    access points  55   
         [0073]    service points  56   
         [0074]    path  57