WO2015124659A1

WO2015124659A1 - Location validation in cellular communication systems

Info

Publication number: WO2015124659A1
Application number: PCT/EP2015/053478
Authority: WO
Inventors: Christopher Edward John Kilgour; Nicholas Dougall Johnson; Neil Philip Piercy; James Edward Brereton Harrow; Alan Whitehead; David Charles Brock
Original assignee: Ip.Access Limited
Priority date: 2014-02-21
Filing date: 2015-02-19
Publication date: 2015-08-27
Also published as: GB2523352B; GB201403067D0; GB2534311B; GB2523352A; GB201604289D0; GB2534311A; GB2534311B8

Abstract

A method for location validation of a UE in a cellular communications system uses measurements on a very low power "presence cell" in order to determine whether a UE is close to the presence cell rather than trying to provide this validation of proximity to the presence cell by accessing service through the presence cell. When the owner of the UE is performing a transaction (for example, a cash withdrawal at a cash machine) for which it is required to verify that their UE is in the immediate vicinity of where that transaction is taking place, a location validation centre may request that the UE takes specific measurements of the signal strength of a cell identified by a particular cell identifier which has been assigned to the presence cell. If the UE can detect the specified presence cell can report this to the location validation centre thereby confirming its location.

Description

LOCATION VALIDATION IN CELLULAR COMMUNICATION SYSTEMS

Field of the invention

The field of this invention relates to network elements and methods for location validation in a cellular communication system

Background of the Invention

Wireless communication systems, such as the 3^rd Generation (3G) of mobile telephone standards and technology, are well known. An example of such 3G standards and technology is the Universal Mobile Telecommunications System (UMTS™), developed by the 3^rd Generation Partnership Project (3GPP™) (www.3gpp.orq). The 3^rd generation of wireless communications has generally been developed to support macro-cell mobile phone communications. Such macro cells utilise high power base stations (NodeBs in 3GPP parlance) to communicate with wireless communication units within a relatively large geographical coverage area. Typically, wireless communication units, or User Equipment (UEs) as they are often referred to in 3G parlance, communicate with a Core Network (CN) of the 3G wireless communication system via a Radio Network Subsystem (RNS). A wireless communication system typically comprises a plurality of radio network subsystems, each radio network subsystem comprising one or more cells to which UEs may attach, and thereby connect to the network. Each macro-cellular RNS further comprises a controller, in a form of a Radio Network Controller (RNC), operably coupled to the one or more Node Bs, via a so-called lub interface.

The second generation wireless communication system (2G), also known as GSM, is a well- established cellular, wireless communications technology whereby "base transceiver stations" (equivalent to the Node B's of the 3G system) and "mobile stations" (user equipment) can transmit and receive voice and packet data. Several base transceiver stations are controlled by a Base Station Controller (BSC), equivalent to the RNC of 3G systems.

Communications systems and networks are developing towards a broadband and mobile system. The 3rd Generation Partnership Project has proposed a Long Term Evolution (LTE) solution, namely, an Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, (E-UTRAN), for a mobile access network, and a System Architecture Evolution (SAE) solution, namely, an Evolved Packet Core (EPC), for a mobile core network. An evolved packet system (EPS) network provides only packet switching (PS) domain data access so voice services are provided by Voice-over-LTE (VoLTE - a VoIP technique) or, via Circuit Switched Fallback (CSFB) by a 2G or 3G Radio Access Network (RAN) and circuit switched (CS) domain network. User Equipment UE) can access a CS domain core network through a 2G/3GRAN such as the (Enhanced Data Rate for GSM Evolution, EDGE) Radio Access Network (GERAN) or a Universal Mobile Telecommunication System Terrestrial Radio Access Network ( UTRAN), and access the EPC through the E-UTRAN. Some User Equipments have the capability to communicate with networks of differing radio access technologies. For example, a user equipment may be capable of operating within a UTRAN and within an E-UTRAN.

Lower power (and therefore smaller coverage area) cells are a recent development within the field of wireless cellular communication systems. Such small cells are effectively communication coverage areas supported by low power base stations. The terms "picocell" and "femtocell" are often used to mean a cell with a small coverage area, with the term femtocell being more commonly used with reference to residential small cells. Small cells are often deployed with minimum RF (radio frequency) planning and those operating in consumers' homes are often installed in an ad hoc fashion. The low power base stations which support small cells are referred to as Access Points (AP's) with the term Home Node B (HNB, specifically for 3G) or Evolved Home Node B (HeNB, specifically for LTE) defined by 3GPP to identify femtocell Access Points. Each small-cell is supported by a single Access Point. These small cells are intended to augment the wide area macro network and support communications to multiple User Equipment devices in an indoor environment or enterprise. Such small cells are intended to be able to be deployed "underneath" a macrocell (in a multi-layer structure, for example) in order to support communications to UEs in a restricted area such as a shopping mall, for example. An additional benefit of small cells is that they can offload traffic from the macro network, thereby freeing up valuable macro network resources). One or more Access Points are linked to a Core Network through an Access Controller. An Access Controller which links one or more HNB's to the Core Network is known as a Home Node B Gateway (HNB-GW). An HNB provides a radio access network connectivity to a user equipment (UE) using the so-called luh interface to a HNB-GW.

Although there are no standard criteria for the functional components of an AP, an example of a typical AP for use within a 3GPP 3G system may comprise Node-B functionality and some aspects of Radio Network Controller (RNC) functionality as specified in 3GPP TS 25.467.

A current industry model is to implement a GSMA one API on one of three places: viz. on the

User Equipment (for handset applications) or on the small cell (for local applications) or on the application Gateway (for external third-party access). The GSMA one API is an application programming interface which has been developed by the GSM (Global System for Mobile Communications) Association. It is intended to be a web service interface. An application developed with one API can obtain information across network operators that support it. It is intended for operation on servers and mobile devices and the first API's to be implemented will be for messaging and location functions. Specifically, version 1 requires "location presence" capability and the ability to send and receive short message services (SMS) and multimedia messaging services (MMS) through the application Gateway using the GSMA one API.

"Presence" services in general permit an individual and equipment which he/she uses for communication to share information on the state of the individual and that equipment. Such information can include whether the individual and his communication equipment are currently able to communicate with others or are engaged on a video call, for example. "Presence" can also include information relating to the location of a user's communication equipment. A "presence server" may be provided in such instances for, on detection that a particular UE has entered a particular location, enabling applications that subscribe to a "presence" service to take some form of action. For example, location information can be very useful to retailers and advertisers who may wish to communicate with shoppers who are known to be in a certain location at a certain time, a shopping mall for example. Location information can also be useful in cases where a location validation service is required, for example, if a user is performing a transaction for which it is required to verify that their User Equipment (or mobile phone) is in the immediate vicinity of where the transaction is taking place.

Some current Location Presence services are based on the use of a localised Identity Request sent by an Access Point providing a "presence cell" of small coverage area to a UE it is serving to obtain its IMSI (International Mobile Subscriber Identifier). Such location presence servers can also perform a "location validation service" in order to prove that that a particular UE is in the vicinity of the presence cell, within a few feet of cash dispensing machine, for example. In the known methods, the UE must detect the presence cell during the normal scanning it performs according to the relevant protocol in order to select the best cell to camp onto so that it may use communications services provided by the Access Point "presence cell.".

This method has the drawback that it may take an appreciable time (several or even tens of seconds) for the UE to detect the presence cell, decide it is strong enough to reselect to, and attempt to access it. It also has the drawback that there may be a short period of delay in the user obtaining service or the possibility that the normal user service may be briefly unavailable while the UE is reselecting and registering or location updating to the presence cell. It also has the potential drawback that if the presence cell is located in an area of strong macrocell coverage, then the effective range of the presence cell may be reduced considerably as the UE may find that the macrocell coverage is so strong that it does not need to try to reselect to the presence cell, as it is not the strongest cell, and so will never try to access the presence cell, and thus not be detected by the presence cell.

Thus it would be desirable to provide a method which mitigated the above disadvantages.

Summary of the invention In a first aspect, the present invention provides a method for location validation of a wireless communication unit in a cellular communication system, the method comprising: at a remote controller, sending an instruction to the wireless communication unit to take measurements of broadcasts from a network element supporting a specified cell in the cellular communication system, the specified cell having a unique cell identifier assigned thereto and to report results of said measurements, receiving said results from the wireless communication unit and validating a location of the wireless communication unit depending on the received results.

The method may further include, at the remote controller, sending to a network element supporting a specified cell, an instruction to broadcast a signal including a unique cell identifier. The method may further include, at the remote controller, sending to the network element supporting a specified cell an instruction to change the unique cell identifier included in the broadcast signal over time in accordance with a random, pseudorandom or other unpredictable sequence.

The method may further include, in the remote controller, correlating results from sequential measurements with the pseudorandom sequence.

The method may further include, in the remote controller, generating a validation signal for onward transmission if the results received from the wireless communication unit confirm that the wireless communication unit can detect the broadcast signal from the specified cell.

The cell identifier may comprise at least one of; a Cell Global Identifier (CGI), a frequency, a Base Station Identity Code, a Primary Scrambling Code, a Physical Cell.

In a second aspect, the present invention provides a network element for assisting location validation of a wireless communication unit in a cellular communication system, the network element being arranged to broadcast a signal including a unique cell identifier for reception by a wireless communication unit, sett the unique cell identifier, and receive an instruction from a remote controller to broadcast said signal and wherein the network element is further arranged to transmit a signal for reception by the wireless communication unit indicating that communications services cannot be provided by the network element.

The network element may be implemented in one or more integrated circuit devices.

In one embodiment, a signal processor included in the network element is arranged to autonomously change the unique cell identifier over time in accordance with a random, pseudorandom or other unpredictable sequence.

A memory may be included in the network element for storing a plurality of unique cell identifiers and the signal processor may be arranged to select from the memory a unique cell identifier for broadcasting in a random, pseudorandom or unpredictable sequence.

The network element may be arranged to receive a request from the remote controller to report its current unique cell identifier and to send to the remote controller the current unique cell identifier.

The signal processor may be arranged to autonomously change the unique cell identifier over time and the network element may be arranged to report a current unique cell identifier to the remote controller whenever the unique cell identifier is changed.

The signal processor may be arranged to set the unique cell identifier in accordance with an instruction received by the network element from the remote controller.

In a third aspect, the invention provides an apparatus for location validation in a cellular communication system wherein the apparatus is arranged to send an instruction to a wireless communication unit in the cellular communication system to take measurements of broadcasts from a network element supporting a specified cell in the cellular communication system, the specified cell having a unique cell identifier assigned thereto, receive results of measurements from the wireless communication unit, and validate a location of the wireless communication unit depending on the received results. The apparatus may be arranged to send to a network element supporting a specified cell an instruction to broadcast a signal including a unique cell identifier.

In a fourth aspect, the invention provides a non-transitory computer-readable medium having computer readable instructions stored thereon for execution by a processor to perform a method for location validation in accordance with the first aspect of the invention. The non-transitory computer- readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, an Electrically Erasable Programmable Read Only Memory and a Flash memory.

Known arrangements require that the wireless communication unit (UE or mobile device) tries to access a service via the presence cell (whether by transmitting data, or merely by an attempt to register or by performing a location update onto the cell). In contrast, in one embodiment, the invention uses measurements on a very low power "presence cell" in order to determine whether a user's UE is close to the presence cell rather than trying to provide this validation of proximity to the presence cell by accessing service through the presence cell. Thus the present invention may overcome the disadvantages of known systems by providing a means for the UE to confirm its proximity to the presence cell without the need to have the presence cell provide services of any form to the UE. The UE merely detects broadcasts of the presence cell. The presence cell may be served by a low power access point whose properties will be described below and which does not require any connection to a core network. Hence, the method of the present invention places no additional load on the core network. The access point may operate on any type of Radio Access Technology, such as 2G, 3G or LTE, for example. The coverage area of the access point may lie underneath that of a macrocell, the macrocell operating using 2G, 3G or LTE technology, for example.

A UE which is camped onto the macrocell and comes within range of the presence cell may obtain normal service via the macrocell and may also be capable of making measurements of broadcasts transmitted by the access point and reporting results of such measurements to a location validation centre.

When the owner of the UE is performing a transaction (for example, a cash withdrawal at a cash machine) for which it is required to verify that their UE is in the immediate vicinity of where that transaction is taking place, a location validation centre may request that the UE takes specific measurements of the signal strength of a cell identified by a particular cell identifier which has been assigned to or selected by the presence cell.. A cell identifier may include the locally unique broadcast characteristics which distinguish a particular cell from all other cells in a neighbouring area and typically comprises the combination of; frequency (ARFCN) and Base Station Identity Code (BSIC) if operating in a 2G system or frequency (UARFCN) and Primary Scrambling Code (PSC) if operating in a 3G system or frequency (EARFCN) and Physical Cell Identity (PCI) if operating in an LTE which are used to identify the broadcast information of the presence cell. In addition to these locally unique broadcast characteristics, the cell identifier may include the Cell Global Identity (CGI) which identifies the cell uniquely over a wide area, and is contained in the actual broadcast information. In an alternative embodiment, the UE may be requested to report the Cell Global Identity (CGI) of the cell which is transmitting on a particular frequency and BSIC or PSC or PCI.

In one embodiment, the measurements are requested through an application which runs on the UE and is in contact with the location validation centre and can perform the measurements using the APIs on the UE to perform the measurements.

Alternatively, in another embodiment, the measurements are performed using the Location Services (LCS) protocols of the 3GPP protocols, requesting that a particular CGI be reported as detected or not in order to validate the location.

In one embodiment, the cell identifier, for example, the CGI and/or frequency/BSIC/PCI/PSC of the presence cell could be periodically altered. This periodic alteration may be in accordance with a random, pseudo-random or some unpredictable sequence. Advantageously, such a sequence would be unpredictable by observers, thus preventing fraudulent activity such as a non bona fide entity setting up a broadcasting beacon close to the UE of an individual who is being targeted as a victim of a fraudulent transaction.

In a further embodiment, to prevent fraudulent activity, the request to perform the measurements may include several different cell identifiers, as a single measurement set, or as sequential measurement requests, with some of the measurement requests expecting no or very weak detection if the UE is in the location to be validated, and other cells are likely to be detected. Some of these measurements may also relate to broadcasts from a neighbouring macrocell in order to ensure that the presence cells is still in its original location and has not been moved, or to verify that the correct presence cell has been detected (in cases where re-use of frequencies and/or BSIC/PSC/PCIs throughout a cellular network, for example, is employed).

In a further embodiment, if sequential measurement requests are made and the cell identifier of the presence cell is being regularly changed according to a pseudo-random sequence, the sequential measurements of that cell identifier may be correlated with the expected pseudo-random sequence to make it less likely that an attacker is able to just read one frequency and re-broadcast from a bogus presence cell.

In one embodiment, the presence cell indicates to the UE that it cannot provide services (e.g. Cell Barred, Cell Reserved for Operator Use, that it is a Closed Subscriber Group cell, or similar access control indication), but is still be available for measurements.

Brief Description of the Drawings

Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the drawings. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the respective drawings to ease understanding.

FIG. 1 is a simplified block diagram of a cellular communications system operating in accordance with an embodiment of the invention; and FIG. 2 is a simplified flowchart illustrating an example of a method for location validation in a cellular communications system.

Detailed Description

The inventive concept finds particular applicability in a cellular communication system that supports a number of overlapping communication coverage areas, for example a communication system that comprises a combination of small cells and macro cells. Further, the inventive concept finds applicability in a cellular communication system comprising more than one Radio Access Technology.

Those skilled in the art will recognise and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings.

Referring now to FIG.1 , a macrocell base station 101 provides cellular communications services over a respective coverage area (macrocell) and may operate using a 2G, 3G or LTE radio access technology, for example. The macroell base station 101 may comprise a network element such as a Base Transceiver Station, NodeB or eNodeB for example which can be of conventional design. The macrocell base station 101 can therefore provide a normal service path 102 (radio interface) to and from a User Equipment 103. The User Equipment (UE) 103 is adapted for taking measurements as part of a location validation procedure to be described below. The macrocell base station 101 is connected with a Core Network 104 which operates in a conventional manner. A location validation centre 105 may send and receive messages to and from the UE 103 via the core network 103 and the macrocell base station 101 in a conventional manner, for example, by setting up a data connection with the UE 103. A network element comprising an access point 106 supports a small 'presence' cell which is within the coverage area of the macrocell. The coverage area of the presence cell 105 is relatively small compared with that of the macrocell. The presence cell covers an area including a "transaction site" where the owner/user of the UE 103 may wish to perform a transaction. Such a transaction could be, for example, receiving cash from a cash dispensing machine located at the transaction site, such cash dispensing machine being maintained by a bank, say. The access point 106 is provided with a signal processor 107, a memory 108 and a transmitter 109 for transmitting a broadcast signal for reception by a UE which may enter into the presence cell' coverage area. In one embodiment, there is a communications link 1 10 between the Location validation centre 105 and the access point 106.

In one example, the memory 108 is pre-provisioned with one or more cell identifiers. A cell identifier uniquely identifies the presence cell and distinguishes it from other cells in the area, for example the macrocell.. The signal processor 107 is arranged to set a cell identifier for broadcasting by the transmitter 109, by selecting one from the memory 108. In one example, the signal processor 107 is preprogrammed to change the transmitted cell identifier periodically in a pseudorandom fashion. Hence the signal processor 107 autonomously changes the specified cell identifier over time. Pre-provisioning of the memory 108 may be done by the location validation centre 105 over the communications link 1 10 with the access point 106.

In another example, the location validation centre 105 sends instructions, over the communications link 1 10, to the access point106 instructing the signal processor 107 to set a cell identifier specified by the location validation centre. The signal processor receives this instruction and responds accordingly.

In another example, the location validation centre 105 sends instructions, over the communications link 1 10, to the access point 106 instructing it to report its current cell identifier.

Hence, the signal processor 107 is configured to receive such an instruction and in response the access point sends a message back to the location validation centre 105 vis its transmitter 109 reporting its current cell identifier.

In another example, the access point 106 autonomously reports, over the communications link

1 10, its current cell identifier to the location validation centre 105 whenever it is set or changed autonomously by the signal processor 107.

In other examples, the instruction from the location validation centre 105 to the signal processor 106 includes instructions to change the cell identifier in a pseudorandom or other unpredictable fashion.

In some examples, a cell identifier comprises at least one of; a Cell Global Identifier, a frequency, a Base Station Identity Code, a Primary Scrambling Code, a Physical Cell Identity. The location validation centre acts as a remote controller for the presence cell inasmuch as it is aware of the location and cell identifier of the presence cell, eg, its CGI, frequency, BSIC, PSC, PCI and other such parameters as appropriate to the RAT which the presence cell operates on.

In one example, in addition to broadcasting a signal having a particular cell identifier, the transmitter 109 also transmits an indicator that the presence cell cannot be used for normal communication services.

Examples of operation of the invention will now be described. A UE 103 is "camped onto" the macrocell and can therefore receive paging messages from any entity via the core network 103. The user of the UE then approaches the transaction site (which is within the coverage area of the presence cell) and commences to access the cash dispensing machine which is maintained by a bank. Before the bank allows any transaction to complete, the bank sends a request to the location validation centre 105 asking for confirmation that the UE belonging to user is actually at the location of the cash machine. In response, the location validation centre 105 sends an instruction to the access point 106 instructing it to broadcast a specified cell identifier. In response, the access point 106 transmits the appropriate broadcast signal which is capable of detection by the UE 103. The location validation centre 105 also calls the UE 103 and sends an instruction to the UE 103 to take measurements of a cell which has the specified cell identifier and to report back to the location validation centre a result of the measurement. Thus, the UE 103 is instructed to search for the presence cell supported by the access point106 and if it is detected, to measure a parameter of the broadcast signal such as signal strength or path loss, as is conventional in UE neighbouring cell measurement procedures. In response the UE 103 performs the required measurement and sends back a result to the location validation centre 105. The results could comprise for example, a value of signal strength or a confirmatory message confirming that the presence cell has been detected or that its received signal strength is above a particular threshold or that no cell with the specified cell identifier could be detected. Another example result could be the CGI of a cell broadcasting on a particular frequency, the particular frequency serving as the "cell identifier" notified to the UE 103 by the location validation centre 105. If the access point 106 is also transmitting an indicator that services are not available then the UE 103 will not attempt to reselect onto the presence cell but maintain its connection to the macrocell served by the macrocell base station101 .

In another embodiment, the location validation centre 105 also instructs the UE 103 to measure the signal strength of transmissions from the macrocell base station 101 and send a result back to the location validation centre. Such a result may comprise a value of this signal strength. On receipt of such an instruction, the UE 103 may perform such a measurement and send an appropriate result back to the location validation centre over the communications link supported by the macrocell base station 101 and core network 104.

At the location validation centre 105, on receipt of a result from the UE 103 which confirms that the UE has detected a broadcast signal from the access point 106 and therefore must be close to the transaction site, the location validation centre 105 can then validate the location of the user and generate and send a confirmatory message to the bank so that the bank may instruct its cash machine to continue with the transaction. If on the other hand the results sent by the UE 103 signify that either the presence cell could not be detected or that a detected broadcast signal strength was below a threshold value, then the location validation centre 105 will not validate the location of the user and may notify the bank accordingly.

In embodiments where the transmitted cell identifier is varied in accordance with a pseudorandom sequence, the location validation centre 105 may perform a correlation between results from sequential UE measurements with the pseudorandom sequence.

In embodiments where the UE takes measurements of broadcasts from the macrocell base station 101 , the location validation centre 105 uses the results received from the UE 103 relating to these measurements to corroborate the results received which relate to the presence cell measurements.

Referring now to Fig. 2, at 201 , the location validation centre 105 sends an instruction to the access point 106 supporting the presence cell to broadcast signals containing a specified unique cell identifier. At 202, a UE 103 is in idle mode and "camped on' to the macrocell. At 203, the UE moves towards the transaction site and the user of the UE then attempts some transaction at the site. As a result of this attempt, the location validation centre is requested, by a bank, for example, to validate that the UE of a user is actually at the transaction site. At 204, the location validation centre 105 sends the instruction to the UE 103 to take measurements of the (specified) presence cell. At 205, the UE 103 detects broadcasts from the presence cell and identifies it as the specified cell by detecting its cell identifier. At 206, the results of the measurements are sent from the UE 103 to the location validation centre 105. Depending on the results, the location validation centre may validate (at 207) the presence of the UE at the transaction site and notify the bank accordingly.

The functionality of the embodiments of the invention, particularly those functions performed by the signal processor 107 of the access point supporting the presence cell may be achieved using computing systems or architectures known to those who are skilled in the relevant art. Computing systems such as, a desktop, laptop or notebook computer, hand-held computing device (PDA, cell phone, palmtop, etc.), mainframe, server, client, or any other type of special or general purpose computing device as may be desirable or appropriate for a given application or environment can be used. The computing system can include one or more processors which can be implemented using a general or special-purpose processing engine such as, for example, a microprocessor, microcontroller or other control module.

The computing system can also include a main memory, such as random access memory (RAM) or other dynamic memory, for storing information and instructions to be executed by a processor. Such a main memory also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor. The computing system may likewise include a read only memory (ROM) or other static storage device for storing static information and instructions for a processor.

The computing system may also include an information storage system which may include, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a compact disc (CD) or digital video drive (DVD) read or write drive (R or RW), or other removable or fixed media drive. Storage media may include, for example, a hard disk, floppy disk, magnetic tape, optical disk, CD or DVD, or other fixed or removable medium that is read by and written to by media drive. The storage media may include a computer-readable storage medium having particular computer software or data stored therein.

In alternative embodiments, an information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computing system. Such components may include, for example, a removable storage unit and an interface , such as a program cartridge and cartridge interface, a removable memory (for example, a flash memory or other removable memory module) and memory slot, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage unit to computing system.

The computing system can also include a communications interface. Such a communications interface can be used to allow software and data to be transferred between a computing system and external devices. Examples of communications interfaces can include a modem, a network interface (such as an Ethernet or other NIC card), a communications port (such as for example, a universal serial bus (USB) port), a PCMCIA slot and card, etc. Software and data transferred via a communications interface are in the form of signals which can be electronic, electromagnetic, and optical or other signals capable of being received by a communications interface medium. In this document, the terms 'computer program product', 'computer-readable medium' 'non- transitory computer-readable medium' and the like may be used generally to refer to tangible media such as, for example, a memory, storage device, or storage unit. These and other forms of computer- readable media may store one or more instructions for use by the processor comprising the computer system to cause the processor to perform specified operations. Such instructions, generally referred to as 'computer program code' (which may be grouped in the form of computer programs or other groupings), when executed, enable the computing system to perform functions of embodiments of the present invention. Note that the code may directly cause a processor to perform specified operations, be compiled to do so, and/or be combined with other software, hardware, and/or firmware elements (e.g., libraries for performing standard functions) to do so.

In an embodiment where the elements are implemented using software, the software may be stored in a computer-readable medium and loaded into computing system using, for example, removable storage drive. A control module (in this example, software instructions or executable computer program code), when executed by the processor in the computer system, causes a processor to perform the functions of the invention as described herein.

Furthermore, the inventive concept can be applied to any circuit for performing signal processing functionality within a network element. It is further envisaged that, for example, a semiconductor manufacturer may employ the inventive concept in a design of a stand-alone device, such as a microcontroller of a digital signal processor (DSP), or application-specific integrated circuit (ASIC) and/or any other sub-system element.

It will be appreciated that, for clarity purposes, the above description has described embodiments of the invention with reference to a single processing logic. However, the inventive concept may equally be implemented by way of a plurality of different functional units and processors to provide the signal processing functionality. Thus, references to specific functional units are only to be seen as references to suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organisation.

Aspects of the invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may optionally be implemented, at least partly, as computer software running on one or more data processors and/or digital signal processors or configurable module components such as FPGA devices. Thus, the elements and components of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term 'comprising' does not exclude the presence of other elements or steps. Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by, for example, a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Also, the inclusion of a feature in one category of claims does not imply a limitation to this category, but rather indicates that the feature is equally applicable to other claim categories, as appropriate.

Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. In addition, singular references do not exclude a plurality. Thus, references to 'a', 'an', 'first', 'second', etc. do not preclude a plurality.

Claims

1 . A method for location validation of in a wireless communication unit (103) in a cellular communication system, the method comprising: at a remote controller (105), sending (204) an instruction to the wireless communication unit to take measurements of broadcasts from a network element (106) supporting a specified cell in the cellular communication system, said specified cell having a unique cell identifier assigned thereto, and to report results of said measurements; receiving (206) said results from the wireless communication unit and validating (207) a location of the wireless communication unit depending on the received results.

2. The method of claim 1 including; at the remote controller, sending (201 ) to the network element supporting the specified cell an instruction to broadcast a signal including a unique cell identifier.

3. The method of claim 2 including; at the remote controller, sending to the network element supporting the specified cell an instruction to change the unique cell identifier included in the broadcast signal over time in accordance with a random, pseudorandom or other unpredictable sequence.

4. The method of claim 3 including: in the remote controller, correlating results from sequential measurements with the pseudorandom sequence.

5. The method of any preceding claim including: in the remote controller, generating (207) a validation signal for onward transmission if the results received from the wireless communication unit confirm that the wireless communication unit can detect the broadcast signal from the network element supporting the specified cell.

6. The method of any preceding claim wherein the cell identifier comprises at least one of; a Cell Global Identifier (CGI), a frequency, a Base Station Identity Code, a Primary Scrambling Code, a Physical Cell Identity.

7. A network element (106) for assisting location validation of a wireless communication unit (103) in a cellular communication system, the network element being arranged to broadcast a signal including a unique cell identifier for reception by a wireless communication unit, sett the unique cell identifier, and receive an instruction from a remote controller (105) to broadcast said signal and wherein the network element is further arranged to transmit a signal for reception by the wireless communication unit indicating that communications services cannot be provided by the network element.

The network element (106) of claim 7 including a signal processor (107) wherein the signal processor is arranged to autonomously change the unique cell identifier over time in accordance with a random, pseudorandom or other unpredictable sequence.

The network element (106) of claim 8 including a memory (108) for storing a plurality of unique cell identifiers and wherein the signal processor (107) is arranged to select from the memory a unique cell identifier for broadcasting in a random, pseudorandom or unpredictable sequence.

10. The network element (106) of any of claims 7 to 9 and arranged to receive a request from the remote controller to report its current unique cell identifier and to send to the remote controller the current unique cell identifier.

1 1 . The network element (106) of claim 8 and arranged to report a current unique cell identifier to the remote controller (105) whenever the unique cell identifier is changed.

12. The network element (106) of claim 7 including a signal processor wherein the signal processor is arranged to set the unique cell identifier in accordance with an instruction received by the network element from the remote controller (105).

13. Apparatus (105) for location validation in a cellular communication system wherein the apparatus is arranged to send an instruction to a wireless communication unit (103) in the cellular communication system to take measurements of broadcasts from a network element (106) supporting a specified cell in the cellular communication system, the specified cell having a unique cell identifier assigned thereto, receive results of measurements from the wireless communication unit, and validate a location of the wireless communication unit depending on the received results.

The apparatus (105) of claim 13 arranged to send to the network element (106) supporting a specified cell an instruction to broadcast a signal including a unique cell identifier. A non-transitory computer-readable medium having computer-readable instructions stored thereon for execution by a processor to perform a method in accordance with claim