Patent Publication Number: US-2011053606-A1

Title: Method and device for notifying a location services client that a target terminal is unreachable

Description:
FIELD OF THE DISCLOSURE 
     The present invention relates generally to location services for portable electronic devices, and in particular to notifying a location services client that a target terminal is unreachable. 
     BACKGROUND 
     Mobile telephones and other portable electronic devices increasingly include a locating feature that enables a current geographic location of the devices to be either displayed on the devices or transmitted to a remote receiver. These features are generally called location services (abbreviated as LCS, for “LoCation Services”). LCS features that display location coordinates on a device are useful, for example, to device users who need to know where they are located relative to geographic map coordinates. Thus, LCS features can enable a device user to initiate a location request where the device acts as a Global Positioning System (GPS) terminal. Also, location requests may be initiated by third parties and transmitted to a device over a wireless network. Such third party requests are useful in various circumstances. For example, mobile telephone networks may be able to improve network efficiency and provide better Quality of Service (QoS) and roaming rates to a mobile user if the network can periodically monitor a mobile telephone location. Also, emergency services can sometimes save lives by rapidly and accurately identifying where emergency phone calls have originated. Other useful location-based services and data that can be provided through portable electronic devices include maps, weather forecasts, traffic data and local news. 
     Various locating technologies can be used to determine the location of a portable electronic device. For example, the Global Positioning System (GPS) can be used to identify a location anywhere in the world of some mobile telephones. Further, because mobile telephones are already operatively connected to land-based network stations, the stations can transmit GPS satellite orbit parameters and navigation data to mobile telephones to aid fast acquisition of GPS satellites when a mobile telephone first starts its GPS function. Thus Assisted GPS (A-GPS) services are commonly used to incorporate better and more efficient location services into mobile telephones. Secure User Plane Location (SUPL) is a technology developed by the Open Mobile Alliance (OMA) that concerns the transfer of assistance data and positioning data between a portable electronic device and a location platform, and includes standards such as the Open Mobile Alliance Secure User Plane Location 2.0 Periodic Trigger standard. A “user plane” means that assistance data and positioning data are transmitted between the device and the location platform over a conventional wireless communication channel such as a General Packet Radio Service (GPRS) channel. User plane communications are thus distinguished from control plane communications where assistance data and positioning data are transmitted between a device and a location platform over a packet switched (PS) channel in a network. 
     Other SUPL applications include monitoring the location of one or more mobile devices from a remote location. For example, a dispatch center of a delivery company or a command station of an emergency response team may need to monitor the location of individuals or vehicles in the field. In such applications the dispatch center or command station is referred to as an LCS client and monitored electronic devices are referred to as target SUPL Enabled Terminals (SETs). The LCS client receives location data concerning a SET indirectly through a SUPL location server. 
     However, after an LCS session is established between an LCS client and a SUPL location server concerning a particular target SET, if the target SET is subsequently powered off or otherwise becomes out of service, the SUPL location server may continue to report the most recently updated location information of the target SET to the LCS client, which information may be inaccurate. That can result in inaccurate location information being used by the LCS client, and waste processing and power resources of both the LCS client and the SUPL location server. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views, together with the detailed description below, are incorporated in and form part of the specification, and serve to further illustrate embodiments of concepts that include the claimed invention, and explain various principles and advantages of those embodiments. 
         FIG. 1  is a schematic diagram illustrating a wireless communication network that provides location services, according to an embodiment of the present invention. 
         FIG. 2  is a message sequence chart illustrating a method for notifying an LCS client that a target SET is unreachable, according to an embodiment of the present invention. 
         FIG. 3  is a message sequence chart illustrating a method for notifying an LCS client that a target SET is unreachable, according to another embodiment of the present invention. 
         FIG. 4  is a flow diagram illustrating a method for notifying a location services client that a target terminal is unreachable, according to an embodiment of the present invention. 
         FIG. 5  is a block diagram illustrating components of a location server, according to an embodiment of the present invention. 
     
    
    
     Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. 
     The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
     DETAILED DESCRIPTION 
     According to some embodiments of the present invention, a method enables notifying a location services client that a target terminal is unreachable. The method includes receiving at a location server from the location services client a location reporting request message that requests information about the location of the target terminal. A positioning session is then established between the location server and the target terminal. Next, it is determined at the location server that a location report from the target terminal is overdue and that the target terminal is unreachable. Finally, a notification message is transmitted from the location server to the location services client indicating that the target terminal is unreachable. 
     Embodiments of the present invention thus enable an LCS client to be promptly notified when a location server may be unable to accurately report a position of a target terminal because, for example, the target terminal has become out of service or has been powered off. The LCS client is then able to terminate the positioning session with the location server and employ alternative locating methodologies. The LCS client is thus less likely to use inaccurate or outdated positioning data, and processor and power resources of the LCS client, the location server, and the network in which they operate, can be conserved. 
     Referring to  FIG. 1 , a schematic diagram illustrates a wireless communication network  100  that provides location services, according to an embodiment of the present invention. A target SET  105  in the form of a mobile telephone is in radio frequency (RF) communication with a satellite  110  and a cell tower  115 . The satellite  110  is in communication with a location server  120  in the form of a SUPL location platform (SLP) through a GPS receiver  125  and a wide area reference network  130 . The cell tower  115  is also in communication with the location server  120  through a user plane  135 . The location server  120  is further operatively connected to a home location register (HLR)  140  of the target SET  105 , a terrain database  145 , and a mobile location protocol (MLP) interface  150  that interfaces with an LCS client  155 . As will be understood by those having ordinary skill in the art, the LCS client  155  can be any device or system that requests the services of the location server  120 , such as another mobile telephone, computer, or computer server. 
     The wide area reference network  130  is operatively coupled to a SUPL positioning center  160 , which interacts with a LUP interface  165 . The LUP interface  165  is used to deliver messages to and from the SET  105  for SUPL service management and SUPL positioning determination. 
     A serving cell area processing block  170  processes information concerning a serving cell area in which the target SET  105  operates. Further, an enhanced cell identification (ID) processing block  175  estimates the position of the target SET  105  based on an identification of the serving cell area in which the target SET  105  operates. 
     Referring to  FIG. 2 , a message sequence chart illustrates a method for notifying the LCS client  155 , in the wireless communication network  100 , that the target SET  105  is unreachable, according to an embodiment of the present invention. First, a mobile location platform trigger location reporting request (MLP TLRR) message  205  is transmitted from the LCS client  155  to the location server  120 , and requests information about the location of the target SET  105 . The location server  120  then transmits a user plane location protocol (ULP) SUPL initiation message  210  to the target SET  105 , which message  210  initiates a network initiated SUPL positioning process. A data connection setup process  215  is then performed at the target SET  105 , and the target SET  105  transmits a ULP SUPL triggered start message  220  back to the location server  120  to negotiate parameters of the positioning process with the location server  120 . The location server  120  then transmits to the target SET  105  a ULP SUPL triggered response message  225 , which is used to negotiate further parameters of the positioning process. The location server  120  also transmits to the LCS client  155  a MLP triggered location reporting answer (TLRA) message  230 , which is an MLP protocol message that informs the LCS client  155  of the result of the MLP TLRR message  205 . 
     The target SET  105  then responds to the location server  120  with a ULP SUPL position initiation message  235 , which is a further ULP protocol message. A ULP SUPL positioning process  240 , which is initiated by the location server  120 , is then performed between the location server  120  and the target SET  105 . The location server  120  then transmits to the target SET  105  a ULP SUPL report message  245 , which requests a location report from the target SET  105 . The target SET  105  then responds with another ULP SUPL report message  250 , which delivers a GPS position result to the location server  120 . The GPS position result is then transmitted from the location server  120  to the LCS client  155  in the form of a MLP trigger location report (TLREP) message  255 . 
     Subsequently, the location server  120  expects to receive periodic additional ULP SUPL report messages from the target SET  105  and to transmit periodic additional MLP TLREP messages to the LCS client  155 . However, if a particular “interval  1 ” of time expires after the location server  120  received the last ULP SUPL report message  250 , then at block  260  the location server  120  determines that a ULP SUPL report message is overdue and changes to a backup positioning method such as a cell identification positioning method. As known by those having ordinary skill in the art, such a backup positioning method is generally significantly less accurate than a preferred positioning method such as AGPS. The location server  120  then transmits another MLP TLREP message  265 , including positioning data obtained from the backup positioning method, to the LCS client  155 . 
     According to one embodiment of the present invention, after the “interval  1 ” expires a missing report counter is incremented by one. Then, after each additional period of time equivalent to the period of “interval  1 ” expires, the missing report counter is further incremented by one. Finally, at block  270  the missing report counter reaches a predetermined value of “N”, such as a value between three and five set based on network congestion conditions, and it is determined at the location server  120  that the target SET  105  is unreachable. Therefore, a mobile application part (MAP) any_time_interrogation request message  275  is transmitted from the location server  120  to the HLR  140  over an Lh interface, which message  275  requests a status of the target SET  105 . The HLR  140  then informs the location server  120  of a current status of the target SET  105 . For example, the HLR  140  transmits a MAP any_time_interrogation response message  280  to the location server  120  that indicates that the target SET  105  is powered off. Alternatively, the HLR  140  may transmit a message to the location server  120  indicating that the target SET  105  is out of service. The location server  120  then transmits a stop session message  285  to the LCS client  155 . 
     It will be understood by those having ordinary skill in the art the above example concerns networks such as global system for mobile (GSM) communication networks, wideband code division multiple access (WCDMA) networks, and time division synchronous-code division multiple access (TDS-CDMA) networks. Similar methods can be applied to other mobile communication networks such as CDMA2000 and worldwide interoperability for microwave access (WiMax) networks. 
     When the LCS client  155  receives the stop session message  285 , the LCS client  155  can recognize that it is unable to obtain accurate positioning data concerning the target SET  105 . The LCS client  155  is thus less likely to use inaccurate or outdated positioning data and, by terminating the positioning session with the location server  120 , processor and power resources of the LCS client  155 , the location server  120 , and the wireless communication network  100  can be conserved. 
     Referring to  FIG. 3 , a message sequence chart illustrates a method for notifying the LCS client  155 , in the wireless communication network  100 , that the target SET  105  is unreachable, according to another embodiment of the present invention. Similar to the initial message exchanges illustrated in  FIG. 2 , regarding  FIG. 3  a mobile location platform trigger location reporting request message (MLP TLRR)  305  is first transmitted from the LCS client  155  to the location server  120 , and requests information about the location of the target SET  105 . The location server  120  then transmits a user plane location protocol (ULP) SUPL initiation message  310  to the target SET  105 , which message  310  initiates a network initiated SUPL positioning process. A data connection setup process  315  is then performed at the target SET  105 , and the target SET  105  transmits a ULP SUPL triggered start message  320  back to the location server  120  to negotiate parameters of the positioning process with the location server  120 . The location server  120  then transmits to the target SET  105  a ULP SUPL triggered response message  325 , which is used to negotiate further parameters of the positioning process. The location server  120  also transmits to the LCS client  155  a MLP triggered location reporting answer (TLRA) message  330 , which is an MLP protocol message that informs the LCS client  155  of the result of the MLP TLRR message  305 . 
     The target SET  105  then responds to the location server  120  with a ULP SUPL position initiation message  335 , which is a further ULP protocol message. A ULP SUPL positioning process  340 , which is initiated by the location server  120 , is then performed between the location server  120  and the target SET  105 . The location server  120  then transmits to the target SET  105  a ULP SUPL report message  345 , which requests a location report from the target SET  105 . The target SET  105  then responds with another ULP SUPL report message  350 , which delivers a GPS position result to the location server  120 . The GPS position result is then transmitted from the location server  120  to the LCS client  155  in the form of a MLP trigger location report (TLREP) message  355 . 
     Subsequently, the location server  120  expects to receive periodic additional ULP SUPL report messages from the target SET  105  and to transmit periodic additional MLP TLREP messages to the LCS client  155 . However, after expiration of a predetermined period assigned to a heart_beat_timer, which can comprise various types of conventional clocking or timing mechanisms known to those having ordinary skill in the art, the location server  120  transmits a MAP any_time_interrogation request message  360  to the HLR  140 . The message  360  requests a status of the target SET  105 . The HLR  140  then informs the location server  120  of a current status of the target SET  105 . For example, the HLR  140  transmits a MAP any_time_interrogation response message  365  to the location server  120  that indicates that a status of the target SET  105  is normal. The location server  120  then continues to receive periodic messages, such as a ULP SUPL report message  370 , from the target SET  105 , and transmits regular positioning update messages, such a MLP TLREP message  375 , to the LCS client  155 . 
     If the predetermined period of the heart_beat_timer again expires, the location server  120  transmits another MAP any_time_interrogation request message  380  to the HLR  140 . The HLR  140  then transmits to the location server  120  another MAP any_time_interrogation response message  385  that indicates that the target SET  105  is powered off or out of service. The location server  120  then transmits a stop session message  390  to the LCS client  155 . Similar to the embodiment illustrated in  FIG. 2 , the LCS client  155  is thus less likely to use inaccurate or outdated positioning data and, by terminating the positioning session with the location server  120 , processor and power resources of the LCS client  155 , the location server  120 , and the wireless communication network  100  can be conserved. 
     Referring to  FIG. 4 , a flow diagram illustrates a method  400  for notifying a location services client that a target terminal is unreachable, according to an embodiment of the present invention. At step  405  a location server receives from the location services client a location reporting request message that requests information about the location of the target terminal. For example, as described above, the location server  120  receives a MLP TLRR message, such as the message  205  or the message  305 , from the LCS client  155 . 
     At step  410 , a positioning session is established between the location server and the target terminal. For example, as described above, a positioning session is established between the location server  120  and the target SET  105  through the ULP SUPL positioning process  240  or the ULP SUPL positioning process  340 . 
     At step  415  the location server transmits to the location services client, after establishing the positioning session between the location server and the target terminal, location data received from the target terminal. For example, the MLP TLREP messages  255 ,  355  are transmitted from the location server  120  to the LCS client  155 . 
     At step  420 , the location server determines that a location report from the target terminal is overdue. For example, determining that a location report from the target terminal is overdue may comprise determining that a missing report counter has exceeded a predetermined threshold. As described above, that may include at block  270  the missing report counter reaching a predetermined value of “N”. Alternatively, determining that a location report from the target terminal is overdue may comprise determining that a timer of location reports received from the target terminal has expired. As described above, that may include determining at the location server  120  that a heart_beat_timer has expired and then transmitting the MAP any_time_interrogation request message  380  from the location server  120  to the HLR  140 . 
     At step  425 , the location server determines, in response to determining that the location report is overdue, that the target terminal is unreachable. For example, as described above, the location server  120  determines that the target SET  105  is unreachable by processing the MAP any_time_interrogation response message  280 , or the message  385 , received from the HLR  140  and indicating that the target SET  105  is powered off. 
     At step  430 , the location server transmits to the location services client a notification message indicating that the target terminal is unreachable. For example, as described above, the stop session message  285  or message  390  is transmitted from the location server  120  to the LCS client  155 . 
     Referring to  FIG. 5 , a block diagram illustrates components of the location server  120 , according to an embodiment of the present invention. The location server  120 , for example, can comprise a SUPL location platform (SLP) containing at least all the elements depicted in  FIG. 5 , as well as any other elements necessary for the location server  120  to perform its particular functions. Alternatively, the location server  120  can comprise a collection of appropriately interconnected units or devices, wherein such units or devices perform functions that are equivalent to the functions performed by the elements depicted in  FIG. 5 . 
     The location server  120  comprises a random access memory (RAM)  505  and a programmable memory  510  that are coupled to a processor  515 . The processor  515  also has ports for coupling to network interfaces  520 ,  525 . The network interfaces  520 ,  525  can be used to enable the location server  120  to communicate with other devices in various types of wired or wireless communication networks. For example the network interface  520  may communicate with the MLP interface  150  that enables the location server  120  to transmit MLP messages, such as the MLP TLREP message  375 , to the LCS client  155 . 
     The programmable memory  510  can store operating code (OC) for the processor  515  and code for performing functions associated with a location server. For example, the programmable memory  510  can store computer readable program code components  540  configured to cause execution of a method, such as the method  400 , for notifying a location services client that a target terminal is unreachable, as described herein. 
     Methods according to some embodiments of the present invention conform to the Open Mobile Alliance Secure User Plane Location 2.0 standard. 
     Wireless portable electronic devices, such as the target SET  105 , that utilize and benefit from embodiments of the present invention can utilize various types of wireless network architectures including a mesh enabled architecture (MEA) network, or an Institute of Electrical and Electronics Engineers (IEEE) 802.11 network (e.g., 802.11a, 802.11b, 802.11g, 802.11n). It will be appreciated by those of ordinary skill in the art that such wireless communication networks can alternatively comprise any packetized communication network where packets are forwarded across multiple wireless hops. For example, such a wireless communication network can be a network utilizing multiple access schemes such as OFDMA (orthogonal frequency division multiple access), TDMA (time division multiple access), FDMA (Frequency Division Multiple Access), or CSMA (Carrier Sense Multiple Access). 
     Advantages of some embodiments of the present invention therefore include enabling an LCS client to be promptly notified when a location server is unable to accurately report a position of a target terminal because, for example, the target terminal has become out of service or has been powered off. The LCS client is thus less likely to use inaccurate or outdated positioning data, and processor and power resources of the LCS client, the location server, and the network in which they operate can be conserved. 
     In the foregoing specification, specific embodiments have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present teachings. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued. 
     Moreover in this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “has”, “having,” “includes”, “including,” “contains”, “containing” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, has, includes, or contains a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “comprises a . . . ”, “has a . . . ”, “includes a . . . ”, or “contains a . . . ” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises, has, includes, or contains the element. The terms “a” and “an” are defined as one or more unless explicitly stated otherwise herein. The terms “substantially”, “essentially”, “approximately”, “about” or any other version thereof, are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting embodiment the term is defined to be within 10%, in another embodiment within 5%, in another embodiment within 1% and in another embodiment within 0.5%. The term “coupled” as used herein is defined as connected, although not necessarily directly and not necessarily mechanically. A device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed. 
     It will be appreciated that some embodiments may be comprised of one or more generic or specialized processors (or “processing devices”) such as microprocessors, digital signal processors, customized processors and field programmable gate arrays (FPGAs) and unique stored program instructions (including both software and firmware) that control the one or more processors to implement, in conjunction with certain non-processor circuits, some, most, or all of the functions of the method and system described herein. Alternatively, some or all functions could be implemented by a state machine that has no stored program instructions, or in one or more application specific integrated circuits (ASICs), in which each function or some combinations of certain of the functions are implemented as custom logic. Of course, a combination of the two approaches could be used. 
     Moreover, an embodiment can be implemented as a computer-readable storage medium having computer readable code stored thereon for programming a computer (e.g., comprising a processor) to perform a method as described and claimed herein. Examples of such computer-readable storage mediums include, but are not limited to, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (Read Only Memory), a PROM (Programmable Read Only Memory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory) and a Flash memory. Further, it is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and ICs with minimal experimentation. 
     The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.