The location of a mobile, wireless or wired device is a useful and sometimes necessary part of many services. A Location Information Server (“LIS”) may be responsible for providing location information to such devices with an access network. The LIS may utilize knowledge of the access network and its physical topology to generate and serve location information to devices.
The LIS, in general terms, is a network node originally defined in the National Emergency Number Association (“NENA”) i2 network architecture addressing a solution for providing E-911 service for users of Voice over Internet Protocol (“VoIP”) telephony. In VoIP networks, the LIS is the node that determines the location of the VoIP terminal. Beyond the NENA architecture and VoIP, the LIS is a service provided by an access network provider to supply location information to users of the network by utilizing knowledge of network topology and employing a range of location determination techniques to locate devices attached to the network. The precise methods used to determine location are generally dependent on the type of access network and the information that can be obtained from the device. For example, in a wired network, such as Ethernet or DSL, a wiremap method is commonplace. In wiremap location determination, the location of a device may be determined by finding which cables are used to send packets to the device. This involves tracing data through aggregation points in the network (e.g., Ethernet switches, DSL access nodes) and finding the port for which packets are sent to the device. This information is combined with data available to the LIS (generally extracted from a database) to determine a final location of the device.
In wireless networks, a range of technologies may be applied for location determination, the most basic of which uses the location of the radio transmitter as an approximation. The Internet Engineering Task Force (“IETF”) and other standards forums have defined various architectures and protocols for acquiring location information from an LIS. In such networks, an LIS may be automatically discovered and location information retrieved using network specific protocols. Location information may be retrieved directly or the LIS may generate temporary uniform resource identifiers (“URI”) utilized to provide location indirectly (i.e., location URI). Geodetic and civic positions of a mobile device may be determined as a function of location information from the LIS. There is, however, a need in the art to overcome the limitations of the prior art and provide a novel system and method for a generic application of location determination for network attached devices.
One embodiment of the present subject matter provides a method for determining the location of a target device. The method may comprise receiving a location request for a target device, and determining a plurality of parameters that identify the target device. A most likely path may be selected from a plurality of paths to produce a location of the target device, each path having one or more of the plural determined parameters as an input and one or more measurement results as an output. Measurement information may be collected on the most likely path as a function of one or more of the determined parameters to provide the one or more measurement results. Location information may then be derived for the target device as a function of the one or more measurement results, the derivation utilizing a location determination function that evaluates ones of the plural paths. An estimated location of the target device may then be determined as a function of the respective location information for the selected path.
Another embodiment of the present subject matter provides a method for determining the location of a target device. The method may comprise receiving a location request for a target device and determining a plurality of parameters that identify the target device. Measurement information may be collected as a function of one or more of the plural determined parameters to provide a plurality of measurement results. Location information may then be derived for the target device as a function of one or more of the plural measurement results. This derivation may utilize a location determination function that evaluates one or more paths, each path having one or more of the plural determined parameters as an input and one or more of the plural measurement results as an output. A path from the one or more evaluated paths may be identified as a failed path if location information could not be derived from the identified path. The collection, derivation and identification steps may be iteratively repeated until a most likely path is determined. Upon determining this most likely path, an estimated location of the target device may be determined as a function of the respective location information for the determined path.
A further embodiment of the present subject matter provides an LIS comprising circuitry for receiving a location request for a target device, circuitry for determining a plurality of parameters that identify the target device, and circuitry for selecting a most likely path from a plurality of paths, each path having one or more of the plural determined parameters as an input and one or more measurement results as an output. The LIS may further include circuitry for deriving location information for the target device as a function of one or more measurement results, the derivation utilizing a location determination function that evaluates ones of the plural paths and circuitry for collecting measurement information as a function of one or more of the plural determined parameters to provide the one or more measurement results. The LIS may also include circuitry for determining an estimated location of the target device as a function of the respective location information for the selected path.
These embodiments and many other objects and advantages thereof will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the embodiments.
Various aspects of the present disclosure will be or become apparent to one with skill in the art by reference to the following detailed description when considered in connection with the accompanying exemplary non-limiting embodiments.
With reference to the figures where like elements have been given like numerical designations to facilitate an understanding of the present subject matter, the various embodiments of a system and method for the generic application of location determination for network attached devices are herein described.
As generally discussed above, the Location Information Server (“LIS”) is a network server that provides devices with information about their location. The phrases and respective acronyms of Location Information Server (“LIS”) and Location Server (“LS”) are used interchangeably throughout this document and such should not limit the scope of the claims appended herewith. Devices that require location information are able to request their location from the LIS. In the architectures developed by the IETF, NENA and other standards forums, the LIS may be made available in an exemplary IP access network connecting one or more target devices to the Internet. In other modes of operation, the LIS may also provide location information to other requesters relating to a target device. To determine location information for a target device, an exemplary LIS may utilize a range of methods. The LIS may use knowledge of network topology, private interfaces to networking devices like routers, switches and base stations, and location determination algorithms. Exemplary algorithms may include known algorithms to determine the location of a mobile device as a function of satellite information, satellite assistance data, various downlink or uplink algorithms such as, but not limited to, time difference of arrival (“TDOA”), time of arrival (“TOA”), angle of arrival (“AOA”), round trip delay (“RTD”), signal strength, advanced forward link trilateration (“AFLT”), enhanced observed time difference (“EOTD”), observed time difference of arrival (“OTDOA”), uplink-TOA and uplink-TDOA, enhanced cell/sector and cell-ID, etc., and hybrid combinations thereof.
A location server according to an embodiment of the present subject matter may utilize a range of inputs in order to determine location information for the target device. From a request made of the location server, the location server may determine one or more parameters, e.g., Internet Protocol (“IP”) and Media Access Control (“MAC”) addresses, that uniquely identify the target mobile device. This identification information may be used as an input to an exemplary measurement collection process that produces further information in the form of measurements or measurement results. Measurement information may be data already known to the location server, additional parameters that identify the target mobile device in other ways, and/or parameters relating to the network attachment of the target mobile device. Non-limiting examples include the MAC address of the device, the identity of network nodes from which network traffic to and from the device transits (including any physical connections involved), the location of network intermediaries (e.g., wiring maps), radio timing, signal strength measurements and other terrestrial radio frequency information, and network configuration parameters, to name a few.
There are many models in which an LIS may be utilized. For example,
With reference to
An exemplary location server 302 may take the measurement results produced or supplied from such networks 310-360 and may initiate further measurement collection.
In certain embodiments of the present subject matter, a path may be pre-selected or re-evaluated as each step in the process completes. Because time may play a significant role in the selection of an optimal path, re-evaluation after each step enables the actual time for each measurement collection to be considered, rather than a predicted time. Once a path is selected, the measurements for this path are collected, starting from the initial identification information. Inputs to each measurement collection process may be selected from the output of other measurement collections as required. It should be noted that while the term “path” implies a serial process, such should not limit the scope of the claims appended herewith as multiple measurements may be acquired concurrently (hence in parallel fashion) thus providing that one measurement does not necessarily rely upon the output of any other measurement.
At step 730, a most likely path may be selected from a plurality of paths to produce a location of the target device, each path having one or more of the plural determined parameters as an input and one or more measurement results as an output. At step 740, measurement information may be collected on the most likely path as a function of one or more of the plural determined parameters to provide a plurality of measurement results. In one embodiment, the collection process may be iteratively repeated to collect a predetermined amount of measurement information. Further, measurement results from a previous collecting step may be used as an input to a subsequent collecting step. Exemplary measurement information may be the Internet Protocol address of the target device, Media Access Control address of the target device, Ethernet Hardware Address of the target device or component serving the device, hardware address of the target device or component serving the device, adapter address of the target device or component serving the device, identity of a network node through which network traffic to and from the device transits, location of network intermediaries, radio timing measurements, signal strength measurements, network configuration parameters, and combinations thereof.
Location information for the target device may be derived at step 750 as a function of one or more of the plural measurement results. This derivation may utilize a location determination function that evaluates one or more paths. In one embodiment, this derivation may further include deriving location information as a function of an algorithm that utilizes one or more measurement results as an input or may comprise extracting location information directly from one or more measurement results. At step 760, an estimated location of the target device determined as a function of the respective location information for the selected path. In another embodiment, a path may be identified from the evaluated paths as failed if location information could not be derived therefrom. It should be noted that the number of the plural determined parameters may be increased as an input to thereby increase the number of measurement results provided as outputs; therefore, the step of selecting a most likely path may further comprise selecting a most likely path having the fewest number of measurement results.
In certain circumstances, such as wireless access networks, location information may be calculated from measurement results using an algorithm. For example, in a cellular environment, measurements may be made of the time that particular radio signals are received. A calculation may then be performed on the measurement results to determine an estimated location of the target device. This calculation is generally performed using a customized procedure, and may be implemented in software or using computer readable media. Another embodiment of the present subject matter may also include algorithms that take measurement results as an input and produce location information or other measurement results as an output. Algorithms may be characterized in this embodiment by a set of data provided as an input. Any number or types of algorithms may be incorporated into the graph described above by modeling it as a measurement that takes the given input and produces a specific output. Further, such algorithms may be treated identically to measurement collection, that is, the basic concept may be refined to refer to measurement determination entities.
In the event that a particular measurement determination entity is unable to produce a result, execution of a selected path may not be completed. In this instance, the process may be restarted, but the measurement determination entity that could not produce a result is marked as having failed so that paths traversing this failed entity are not executed. A path that produces a location result, however, may still be considered to be a failure for other reasons. For example, such a path may be considered as a failure if the quality of the respective measurement results is inadequate. In such a case, an exemplary location determination function may be invoked again, and to prevent the same path from being invoked, which would likely produce the exact same result, the last step of the process would be marked or identified as having failed.
Measurement information may be collected at step 830 as a function of one or more of the plural determined parameters to provide a plurality of measurement results. Exemplary measurement information may be the Internet Protocol address of the target device, Media Access Control address of the target device, Ethernet Hardware Address of the target device or component serving the device, hardware address of the target device or component serving the device, adapter address of the target device or component serving the device, identity of a network node through which network traffic to and from the device transits, location of network intermediaries, radio timing measurements, signal strength measurements, network configuration parameters, and combinations thereof.
Location information for the target device may be derived at step 840 as a function of one or more of the plural measurement results. This derivation may utilize a location determination function that evaluates one or more paths, each path having one or more of the plural determined parameters as an input and one or more of the plural measurement results as an output. In one embodiment, this derivation may further include deriving location information as a function of an algorithm that utilizes one or more of the plural measurement results as an input or may comprise extracting location information directly from one or more of the plural measurement results. At step 850, a path from the one or more evaluated paths may be identified as failed if location information could not be derived from the identified path. At step 860, the collection, measurement and derivation steps may be iteratively repeated until a most likely path is determined, and an estimated location of the target device determined as a function of the respective location information for the determined path at step 870. In one embodiment, one or more measurement results from a previous collecting step may be utilized as an input to a subsequent collecting step. It should be noted that the number of the plural determined parameters may be increased as an input to thereby increase the number of measurement results provided as outputs; therefore, the step of selecting a most likely path may further comprise selecting a most likely path having the fewest number of measurement results.
In embodiments of the present subject matter, unless explicitly marked, measurement information collected during the process may be retained for later iterations. This ensures that portions of the process that are executed once do not have to be executed again if they are required in a subsequent iteration of the process. If a failure occurs in the process, the initial data set, which on the first pass consists of the identification information, may also include any measurement results obtained during the first pass. This would enable generation of a shorter, wider and more optimized graph. Data may also be explicitly marked as having been consumed by, a measurement determination entity (e.g., when information is of transitory use).
A refinement on exemplary processes according to embodiments of the present subject matter may enable iterative execution of any particular part of the graph.
For example and with continued reference to
As shown by the various configurations and embodiments illustrated in
While preferred embodiments of the present subject matter have been described, it is to be understood that the embodiments described are illustrative only and that the scope of the invention is to be defined solely by the appended claims when accorded a full range of equivalence, many variations and modifications naturally occurring to those of skill in the art from a perusal hereof.
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