WO2008075078A1

WO2008075078A1 - Mobile device and method of network access control

Info

Publication number: WO2008075078A1
Application number: PCT/GB2007/004937
Authority: WO
Inventors: Mark Tovell; Iain Campbell
Original assignee: Symbian Software Limited
Priority date: 2006-12-21
Filing date: 2007-12-21
Publication date: 2008-06-26

Abstract

A mobile phone (100) which includes a location unit (117), for example, a GPS receiver, and a database of known hotspots. The phone periodically determines its position (301) and compares this to the database of hotspots (303). If the device is within a hotspot (304), the phone makes a temporary record of this (307). When a user attempts to make a call or other connection (401), the phone checks the temporary record (402) and if it determines that the phone is within a hotspot (403), the phone connects to the access point of that hotspot (406) and establishes a VoIP (407) or other data connection.

Description

Mobile Device and Method of Network Access Control

The present invention relates to a mobile communications device which utilises position information to control access to a communications network. The present invention also relates to a method of controlling access to a communications network on the basis of position information.

Background to the Invention and Prior Art

Wireless Local Area Networks (WLANs) are rapidly replacing cable based networks, such as Ethernet networks, at home and in the office. One of the main advantages of WLANs is that a user with a mobile computing device (e.g. a laptop) can easily connect to the Internet when at home or in the office without the need to set up cabling each time a new connection is required. This advantage has resulted in a new breed of commercial networks operating in cafes, bars, universities etc. Previously, providing Internet connectivity to users via their own laptops was not practical when cables were required to connect to wired networks. WLANs provide a practical way for users to connect to the Internet when away from the home. One of the best known WLAN systems is the IEEE 802.11 group of standards, otherwise known as WiFi™.

One of the emerging applications of WLANs is in the field of Voice over Internet Protocol (VoIP) communications. VoIP has received much attention in recent years as a way of providing users with a cheap way of making voice calls. Many homes now have broadband connections which have sufficient bandwidth for voice calls to be made over the Internet. Because the Internet connection is always on, users can make VoIP calls either directly to other users, or via third party servers, and pay little or nothing for the call. This application is obviously limited to home or office users.

It is expected that mobile phone manufacturers will begin to incorporate WiFi™ connectivity into increasing numbers of mobile phones, enabling more users to connect to the Internet without having to pay for access over the a phone's GPRS or 3G connection. One application of WϊFi™ enabled mobiles is VoIP call functionality. Mobile phone calls are amongst the most expensive and it is envisaged that there would be a big market for VoIP calls which could be offered at reduced rates for users with WiFi™ enabled mobiles. Thus, while a user is at home or in the office, they could make VoIP calls at reduced rates, and when the user is away from the home or office, the phone operates as a normal mobile.

A further possibility is that a service provider could provide a service whereby WiFi™ hotspots are provided at strategic locations across a city. As the user roams around the city, the WiFi™ enabled mobile continually searches for available hotspots, if a hotspot is available, the WiFi™ unit instructs the phone to direct any voice calls via the WiFi™ unit using VoIP.

A problem with such a system is that scanning for unknown WiFi™ hotspots consumes a lot of battery power. Based on current battery technology, a typical mobile phone battery would run down very quickly if the phone is constantly scanning for WiFi™ hotspots. Even if a phone scans for hotspots at periodic intervals, for example every ten minutes, the power consumed is still significant and an undesirable drain on the battery. One option is that a user can switch the WiFi™ unit on when they know a hotspot is nearby. However, this is contrary to the aim of such systems which should provide seamless and automatic switch-over in order to improve user experience.

Summary of the Invention

To address at least some of the above problems the present invention provides in one embodiment a mobile phone which includes a location unit, for example, a GPS receiver, and a database of known hotspots. The phone periodically determines its position and compares this to the database of hotspots. If the device is within a hotspot, the phone makes a temporary record of this. When a user attempts to make a call, or create any other type of connection, the phone checks the temporary record and if it determines that the phone is within a hotspot, the phone connects to the access point of that hotspot and establishes a VoIP or other data connection.

In view of the above, the present invention provides a mobile communications device, comprising a first communication unit for connecting the device to access nodes of a first communications network; and a storage unit for storing a database of information indicative of the position of each of said access nodes; wherein the device is arranged to obtain information indicative of the position of the device; and the device is arranged to determine, based on said indicative position information, whether at least one of said nodes is within a predetermined notional range of said device.

Therefore, by providing a mobile device with a list of available access nodes, together with information indicative of its position, it is able to determine when an access node will be available. In a preferred use, the device only scans for access nodes which it has determined to be within range. This reduces the number of scan requests and prevents the device having to continually scan for available access points using, for example, a WLAN connection device. WLAN connection devices use a lot of power when scanning for access nodes. The mobile device of the present invention therefore uses less battery power than an equivalent mobile device which does not make use of position information. Another advantage of this mobile device is that it enables a user to take advantage of cheaper calling plans which may be available via WLANs.

Preferably, the first communications unit is arranged such that, in a first mode, it connects to an access node of said first communications network if said device determines that an access node is within said predetermined notional range.

Preferably, the present invention further comprises a second communications unit for connecting the device to access nodes of a second communications network. The second communications unit may be arranged such that, in the first mode, it connects to an access node of said second communications network if said device determines that none of said access nodes are within said predetermined notional range.

Preferably, the present invention further comprises a handover unit for handing over a connection from said first communications network to said second communications network, if the device moves to a position being greater than said predetermined notional range from an access point. Furthermore, the handover unit may also handover a connection from said second communications network to said first communications network, if the device moves to a position being less than said predetermined notional range from an access point.

In this manner, the mobile device is able to maintain connections if the device moves away from an access point of a WLAN. The device is also able to move a connection from a mobile phone based connection to a WLAN connection, should the user move within range of an access point. This enables the user to take advantage alternative calling plans, even during a call.

Preferably, said first communication unit is arranged to measure the quality of service of any connection established by it. The handover unit is arranged such that handover from the first communication network to the second communication network is performed on the basis of said quality of service measurement.

Preferably, the present invention further comprises a first memory location for storing the time of a handover. The handover unit may be arranged to prevent handover within a predetermined time from the previous handover.. This prevents the device continually handing over when the device is moving around the edge of a WLAN hotspot. Preferably, the device comprises a positioning unit which determines the geographical position of the device. The positioning unit may comprise a receiver for receiving radio positioning signals from a plurality of sources. The radio positioning signals may be generated by a global navigation satellite system.

Preferably, the positioning unit is arranged to determine the position of the device based on signals received via the second communication network.

Preferably, said first communications unit is a wireless local area network unit. The first communications unit may be a IEEE 802.11 unit, also known as a WiFi™ unit.

Preferably, the present invention further comprises an alarm generator for generating an alarm when the range determination unit determines that the device is within range of an access point.

In an alternative embodiment, the present invention provides a mobile communications device, comprising a first communications unit for connecting the device to a first communications network, and a controller for enabling the first communications unit to connect to an access node of said network, if the device is determined to be within a predetermined notional range of at least one of said access nodes, wherein said determination is made by comparison between information indicative of the position of said at least one access point and information indicative of the position of the device.

Preferably, the present invention further comprises a second communications unit for connecting the device to a second communications network.

The second communications unit could be embodied in the same set of hardware and/or software as the first communications unit. For example, both could use the same multi-band antenna, which could be supported by different software for handling the communications over the two different networks. A relatively new technology called Software-Defined Radio enables loadable software to be available to a user so that a mobile device can be configured to adjust its communication method, rather than using dedicated hardware for modulating and de-modulating signals.

The second communications network may be arranged to determine the position of the device, and transmit position information to the second communications unit.

Alternatively, the device may be arranged to determine the position of the device. In particular, the device may further comprise a radio positioning unit which is arranged to determine the position of the device using radio positioning signals.

In another alternative, the controller may be further arranged to determine the position of the device using signals received via said second communication network.

Preferably, said controller is also for enabling the second communications unit to connect to a base station of said second communications network, if the device is determined to be a distance greater than said predetermined notional range from at least one of said access nodes of said first communications network.

Preferably, said first communications network is wireless local area network. Preferably, said second communications network is a mobile phone network.

In yet another embodiment, the present invention provides a method for controlling access to a first communications network, the network comprising at least one access node, the method comprising: determining whether a mobile device is within a predetermined notional range of at least one of said access nodes by comparing information indicative of the position the device with information indicative of the position of said at least one access node. Thus the present invention provides a method for determining whether an access point of a WLAN is in range based on information indicative of the position of a mobile device and information indicative of the position of known access points. This method prevents a mobile device having to scan for available access points using conventional WLAN scanning techniques, which have high power consumption. The other advantage of this method is that it makes it possible for a user of a mobile device to take advantage of cheaper calling plans that may be available via a WLAN.

Preferably, the step of determining is performed in response to a user request for a connection.

Preferably, the present invention further comprises connecting the mobile device to said first communications network if it is determined that an access node is within said predetermined notional range. Preferably, the present invention also comprises connecting the mobile device to an access node of a second communications network if it is determined that an access node of said first network is not within said predetermined range.

In the alternative, the step of determining may be carried out at regular intervals. A temporary record may be created of the result of said determination.

In this case the present invention preferably checks said temporary record for said result of said determination in response to a user request for a connection, and connecting said mobile device to said first communications network if said result indicates that an access node is within said predetermined notional range.

Preferably, the present invention further comprises connecting said mobile device to an access node of a second communications network, if said result indicates that an access node of said first network is not within said predetermined notional range. Preferably, the present invention further comprises handing over an established connection from said first network to said second network if said mobile device moves further than said predetermined notional range from an access node of said first network.

Preferably, the present invention further comprises handing over an established connection from said second network to said first network if said mobile device moves within said predetermined notional range of an access node of said first network.

The step of determining could comprise looking up an access range of an access point in a database.

In yet a further embodiment, the present invention provides a method of populating a database on a mobile communications device with details of a communication network's access nodes, comprising the steps of: scanning for available access nodes; obtaining information indicative of the position of the device if an access node is located; and storing details of the access node together with the information indicative of the position of the device at the time the access node was located.

Thus, if a user purchases a mobile device which has no details concerning available access points stored thereon, this method provides a mechanism by which the database can be populated with data. Once a single entry is made, the user can use the device as described above in connection with the method provided in other embodiments.

Preferably, the step of scanning is initiated by a user of said mobile device. Preferably, the details of said access nodes are stored on said mobile device. Brief Description of the Drawings

The invention will now be described in more detail with reference to the accompanying drawings in which:

Figure 1 shows a mobile device in accordance with an embodiment of the invention;

Figure 2 is a schematic diagram showing the components of the mobile device of Figure 1 ;

Figure 3 is a diagram of an environment in which the mobile device of Figure 1 operates;

Figure 4 is a flow-chart showing a method establishing whether or not an access point is within range of the mobile device of Figure 1 ;

Figure 5 is a flow chart showing a method of establishing a connection between the mobile device of Figure 1 and another device;

Figure 6 is a flow-chart showing a first procedure for handover of a connection established by the mobile device of Figure 1 ;

Figure 7 is a flow-chart showing a second procedure for handover of a connection established by the mobile device of Figure 1 ;

Figure 8 is a flow-chart showing a third procedure for handover of a connection established by the mobile device of Figure 1 ; and

Figure 9 is a flow-chart showing a method for populating an access point database stored on the mobile device of Figure 1. Description of the Embodiments

Referring to Figure 1 , a mobile device 100 comprises an outer casing 101 , which includes an earphone 102 and a microphone 103. The mobile device 100 also includes a keypad 104 and a display 105. The keypad 104 enables a user to enter information into the mobile device 100 and instruct the mobile device to perform the various functions which it provides. For example, a user may enter a telephone number, or select another mobile device from a list stored on the mobile device 100, as well as perform functions such as initiating a telephone call.

Figure 2 is a schematic diagram showing the components of the mobile device 100. The device includes a system bus 106 to which the components are connected and which allows the components to communicate with each other. Here, the components are shown to communicate via a single system bus 106, however in practice the mobile device may include several buses to connect the various components. The components of the mobile device 100 include a processor unit 107, memory 108, an earphone controller 109, a microphone controller 110, a display controller 111 , a keyboard controller 112, a storage device controller 113 and a transceiver 114. Figure 2 shows a single processor unit 107, however in practice the device may include two or more processor units to control different components of the device. In particular, the device 100 may include a baseband processor unit to control a telephony stack, and an application processor to control an operating system and a user interface of the device. The transceiver 114 is also connected to an antenna 115. The mobile device 100 is arranged to communicate, using transceiver 114, with a base station of a mobile phone network (not shown). The storage device controller 113 is connected to a storage device 116 which may be an internal hard drive or a removable storage device such as a flash memory card.

The mobile device 100 also includes a Global Positioning System (GPS) unit 117 and WiFi™ unit 118. The GPS unit 117 includes a GPS signal receiver (not shown). The GPS unit 117 is constructed in a manner familiar to those skilled in the art and is also connected to the system bus 106. The WiFi™ unit 118 is also constructed in a manner familiar to those skilled in the art and is also connected to system bus 106.

The WiFi™ unit 118 may be referred to as a first communications unit and the components of the mobile device 100 which facilitate the establishment of a connection to the mobile phone network may be referred to as a second Communications unit. The second communications unit comprises the transceiver 114 as well as the protocol stacks (not shown) which enable the mobile device 100 connect to connect to different networks. For example, the second communications unit includes a telephony protocol stack for enabling connection with the mobile phone network, and a TCP/IP protocol stack for the establishment of Internet data connections over any established Radio Access Bearers (RABs). The stacks may be implemented in hardware or software.

Referring now to Figure 3, mobile device 100 is shown in relation to an environment 200 which includes mobile phone base stations 201a, 201b which form part of a mobile phone network. As noted above in connection with Figure 1 , the mobile device 100 is arranged to communicate with the mobile phone network when a user makes a telephone call, or otherwise requires a connection via the mobile phone network. Each base station has an associated cell 203a, 203b which represents a geographical area in which a base station can offer services to the mobile device 100.

The mobile phone network may offer services other than circuit switched mobile telephone calls. For example, modern mobile phone systems allow data connections to be established using, for example, GPRS (General Packet Radio Service) packet-switched connections. These connections allow users to connect to the Internet by allowing for the transmission of TCP/IP data packets between a mobile device and a base station over an established RAB. Such connections can be used to carry VoIP calls. The environment 200 also includes WiFi™ hotspots 202a, and 202b. Each hotspot is generated by an associated access point 204a, 204b. The hotspot is a geographical area in which a given access point can provide WiFi™ services to the mobile device 100. The access points 204a, 204b are themselves connected to the Internet. This connection may be made by cable, a cellular telephone network, a PSTN/DECT connection or a line-of- sight microwave link.

Returning to Figure 2, the storage device 116 contains an access point database (not shown) which includes details of known access points. The database includes details of each access point including connection information and the geographical position of each access point. The position information may be in any conventional form familiar to those skilled in the art.

The operation of the mobile device will now be described. The mobile device 100 includes programs (not shown), stored on the storage device 116, which are arranged to perform the following operations. In use, the programs are loaded into memory 108 when required and the instructions defined in the programs are executed by the processor unit 107. Any reference in the following to the processor unit 107 performing a certain function is a reference to the processor unit executing instructions contained within one or more programs.

Referring to Figure 4, assuming that the mobile device 100 is outside hotspots 202a, 202b, but within cell 203a, any attempt by the user to make a phone call or to establish an Internet data connection is made through the mobile phone network. Periodically, the processor unit 107 polls the GPS unit 117 and requests position information (step 301). The GPS unit 117 establishes the mobile device's position in a manner familiar to those skilled in the art and provides the processor unit 107 with this information (step302). The processor unit 107 then compares the position information provided by the GPS unit 117 with the position information stored in the database relating to each access point (step 303). The processor unit 107 then determines if the mobile device is within a predetermined range (e.g. 15 metres) of an access point (step 304). If no access points are in range, the processor updates a temporary position register (not shown) to indicate that no access points are in range (step 305). The temporary position register is located in processor unit 107. The processor unit 107 then waits 30 seconds (step 306) before starting the process again at step 301. This time interval can be any suitable length, and the mobile device may be arranged to allow the user to set a suitable time interval.

The step of determining whether the mobile device 100 is within a predetermined range of an access point may be carried out by a range determination unit. This step may simply involve checking a database to find the geographical range associated with the access point, and determining whether the mobile device is currently within that range.

The range determination unit may be integral to the processor unit 107. A range determination program (not shown) is stored on the storage device 116, and is arranged to perform the range determination calculation. In use, the range determination program is loaded into memory 108 when required and the instructions defined in the program are executed by the processor unit 107. In the preferred embodiment, the range determination unit does not exist as a distinct entity; it is merely embodied by the mobile device's software and the access point database, which together can be used to assess whether the mobile unit is in range of a known access point.

Alternatively, the range determination unit may be a dedicated unit. Such a unit may comprise its own processor unit and memory. In this case, the range determination unit loads a range determination program on to its internal memory. This program may be stored on the storage device 116 or on a read only memory internal to the range determination unit.

In the example shown in Figure 3, the processor unit 107 would determine that the mobile device 100 is within range of access point 204a. The processor unit 107 records this fact in the temporary position register (step 307). The processor also records the connection details of the access point 204a in the temporary position register. The processor unit 107 then waits 60 seconds (step 308) before starting the process again at step 301. In this manner, the temporary position register provides a record of whether or not the mobile device 100 is located within a hotspot. If the mobile device 100 is located within a hotspot, the temporary position register also stores the access point connection information for the access point generating that hotspot.

In an alternative embodiment, the processor unit 107 does not poll the GPS unit 117 at predetermined intervals. Instead, the processor unit 107 only requests position information and determines if an access point is in range when a user attempts to establish a connection. In this manner, the mobile device does not need to include a temporary position register.

Figure 5 is a flow chart showing the procedure for establishing a telephone call between the mobile device 100 and another mobile device or for establishing an Internet connection.

When a user wants to make a telephone call, they enter the telephone number of the person they wish to contact into the mobile device using the keypad 104. The user then presses a predefined key on the keypad to initiate the call (step 401). The processor unit 107 firstly conducts a temporary position register look-up (step 402), and determines whether or not an access point is in range (step 403). If no access point is in range, the mobile device 100 establishes a radio access bearer (or other Over The Air (OTA) interface) with the nearest base station 201a, 201b in the manner familiar to those skilled in the art (step 404). When the user has finished the telephone conversation, the call can be terminated by the user (step 405).

If an access point is in range, the processor unit 107 sends the connection details of the access point 204a to the WiFi™ unit 118, and requests the WiFi™ unit 118 to establish a connection with the access point 204a (step 406). Once the WiFi™ connection is established the mobile phone establishes connection with a call system (not shown). An Internet Protocol (IP) packet data connection is established between the call system and the mobile device 100. Speech data is sent between the mobile device 100 and the call system using the packet data connection (so-called Voice over Internet Protocol (VoIP)). The call system connects the call through to the other user via either a fixed line, a mobile phone connection, or using VoIP, depending on the service used by the other user (step 407). When the user has finished the telephone conversation, the call can be terminated by the user (step 408).

The service provider can provide the user with different call charge plans depending on whether the call is being made via the mobile telephone network, or via a WiFi™ connection. Furthermore, a user could subscribe to one service provider for mobile phone calls, and a different service provider for WiFi™ calls. It is generally anticipated that service providers can provide cheaper call rates for VoIP calls than for traditional mobile phone calls.

The mobile device 100 may also be arranged to provide a user with an alert when the mobile device is within range of a hotspot. Referring to Figure 4, at step 307, if the process unit 107 determines that the mobile device 100 has moved into a hotspot and hence changes the temporary position register to indicate this fact, the processor unit instructs the display controller 111 to display an alarm on the display 105. The alarm may be a text based alarm that informs the mobile device user that a hotspot is in range. In addition, or alternatively, the processor unit instructs a speaker controller (not shown) to produce an audible signal via a speaker (also not shown).

The above process provides an indication to the user that they can now make cheaper calls. In particular, the mobile device may be arranged to provide the user with an alert when the mobile device moves into range of a particular hotspot, or class of hotspots. For example, the user may subscribe to a VoIP calling plan provided by a particular service provider through particular access points. The access point database includes an indication of which access points allow the user to connect to a particular service provider's calling plan. When the user moves within range of a hotspot of one of these access points, the mobile device alerts the user and informs them that they may make calls to the particular service provider whose calling plan they are subscribed to.

The above described embodiment deals with the situation in which the user makes a telephone call and remains in the same location for the duration of the call. While this may be desirable for a user who wishes to take advantage of a particular calling plan, in some cases the user may prefer to be mobile and move away from the hotspot in which they are currently located. This process will now be described in connection with Figure 6.

The process begins when a VoIP connection is established via access point 204a (step 501). The WiFi™ unit 118 continually monitors the Quality of

Service (QoS) which is being provided by the radio connection between the mobile device 100 and access point 204a (step 502). The QoS provides an indication, amongst other things, of the distance between the mobile device

100 and the access point 204a. If the QoS drops below a predetermined level, the processor unit 107 instructs the transceiver.114 to establish a radio access bearer with the nearest mobile phone base station 201a, 202b (step

503). Once the radio access bearer is established, the processor unit 107 agrees with the call system to handover the existing VoIP connection to the radio access bearer (step 504). The processor unit 107 then instructs the WiFi™ unit 118 to terminate its connection with access point 204a (step 505).

In an alternative embodiment, the QoS may be monitored by the call system. When the call system determines that the QoS has dropped below a predetermined level, it initiates the establishment of a mobile phone connection and the handover of the connection. In yet another embodiment, the QoS of the WiFi™ connection is not monitored for the purpose of connection handover. Instead, the mobile device performs the following process which is described in connection with Figure 7.

The process begins when a call or other connection is established via access point 204a (step 601). The processor unit 107 requests that the GPS unit 117 provide it with position information at predetermined time intervals. The time intervals are selected to be very short (e.g. 1 second) so that the processor unit 107 effectively receives continuous information concerning the position of the mobile device 100. The GPS unit 117 then determines the position of the device and provides the processor unit 107 with this information at the end of each predetermined time interval (step 602).

The processor unit 107 then determines whether the mobile device 100 is within the hotspot of the access point to which the WiFi™ unit 118 is currently connected (step 603). This is achieved by comparing the information concerning the current position of the device with the position of the access point to which the WiFi™ unit 118 is connected. The processor unit 107 then determines if the mobile device 100 has moved beyond a predetermined distance from the access point.

If the processor unit 107 determines that the mobile device is more than the predetermined distance from the access point, it instructs the transceiver 114 to establish a radio access bearer with the nearest mobile phone base station 201a, 202b (step 604). Once the radio access bearer is established, the processor unit 107 agrees with the call system to handover the existing VoIP connection to the radio access bearer (step 605). The processor unit 107 then instructs the WiFi™ unit 118 to terminate its connection with access point 204a (step 606).

Another possibility is that a user establishes a mobile phone connection while out of range of any WiFi™ hotspots. The mobile device 100 is arranged to enable handover to a WiFi™ connection should the mobile device move within range of an access point 204a, 204b. This process will be described in connection with Figure 8.

The process begins when a VoIP call is established via base station 201a (step 701). The processor unit 107 requests that the GPS unit 117 provide it with position information at predetermined time intervals. The time intervals are selected to be very short (e.g. 1 second) so that the processor unit 107 effectively receives continuous information concerning the position of the mobile device 100. The GPS unit 117 then determines the position of the device 100 and provides the processor unit 107 with this information at the end of each predetermined time interval (step 702).

The processor unit 107 then determines whether the mobile device 100 is within a hotspot 204a, 204b. This is achieved by comparing the information concerning the current position of the device with the position information, stored in the access point database, concerning each of the available access points. The processor unit 107 then determines if the mobile device 100 moves within a predetermined distance of any of the access points 204a, 204b (step 703).

If the processor unit 107 determines that the mobile device is within the predetermined distance from an access point, it instructs the WϊFi™ unit 118 to establish a WiFi™ connection with that access point (step 704). Once the WiFi™ connection is established, the processor unit 107 agrees with the call system to handover the existing VoIP connection to WiFi™ connection (step 705). The processor unit 107 then instructs the transceiver 114 to terminate its connection with base station 201a (step 706).

In yet another embodiment, the present invention provides for connection handover between hotspots 204a and 204b. In this embodiment, the hotspots 204a and 204b geographically overlap. The process begins when a call or other connection is established via access point 204a. The WiFi™ unit 118 continually monitors the Quality of Service (QoS) which is being provided by the radio connection between the mobile device 100 and access point 204a. The QoS provides an indication, amongst other things, of the distance between the mobile device 100 and the access point 204a. If the QoS drops below a predetermined level, the processor unit 107 instructs the GPS unit 117 to establish the position of the device. The processor unit 107 then compares this position with the access point database to establish whether any other access points are local to the mobile device. In this embodiment, the processor unit 107 checks the access point database and determines that access point 204b is now nearer to the mobile device 100. The processor unit 107 instructs the WiFi™ unit 118 to establish a connection with the access point 204b. The processor unit 107 then agrees with the call system to handover the existing connection to access point 204b. The processor unit 107 then instructs the WiFi™ unit 118 to terminate its connection with access point 204a. This process is carried out without the need for further scanning when the QoS drops below a predetermined level.

It will be appreciated that the above-described handover mechanisms may be carried out either independently or in combination. For example, the mobile device may be arranged so that when the QoS for an existing connection drops below a predetermined level, the device firstly determines whether any other hotspots are available, and if not, the device establishes a connection with the mobile phone network.

When any of the above described handover procedures result in handover, the processor unit 107 makes a record of this fact in a handover time register

(not shown) which is typically located within the processor unit 107. The processor unit 107 refers to this register before initiating any of the handover procedures described above. The processor unit 107 will only allow the handover procedures to begin once a predetermined period of time has elapsed. This is to prevent the phone continually handing over to another connection type in the event that a user is positioned near the edge of a hotspot. In an alternative embodiment, the mobile device 100 does not have GPS unit 117. Instead, the mobile device 100 is arranged to use the signals received from mobile phone base stations to calculate its position using triangulation techniques. The techniques for achieving this are well known to the man skilled in the art and are not repeated here. Other techniques for determining the position of a mobile device may be used in conjunction with the present invention.

In the above described embodiments, the access point database is preloaded with information concerning all of the access points available to the particular mobile device 100. The database may be maintained by a third party system which updates it at regular intervals using standard provisioning technologies known to those skilled in the art. Alternatively a user could purchase new information from a third party, for example if the user wants to subscribe to a new calling plan which requires the user to obtain details of the associated access points. Another alternative would be for the mobile device 100 to be provided with a piece of software which allows a user to manually update and maintain the access point database.

The access point database is arranged to store a number of records, each record relating to a single access point. The access point database comprises a number of fields for storing information relating to each access point. The database includes fields for recording the identity of each access point, including for example the MAC (Media Access Control) address of each access point. The database also includes fields for recording other connection information relating to each access point, for example security information such as WEP (Wired Equivalent Privacy) key details. In addition the database includes a field for recording the exact location of an access point, if known. This field is used to record the exact location of an access point when this information is preloaded on the device, or if the information is subsequently purchased from a third party, or otherwise provided to the device. The database also includes a field to record the estimated position of an access point. This is used instead of the exact location field in the event that the mobile device calculates the position of the access point, as will be described below. The database preferably also includes information specifying the geographical area within which the access point can be accessed by a mobile device. The database may also include a field to indicate whether a particular service provider can be accessed through a given access point. It may also contain any other fields as may be deemed necessary for any given implementation of the present invention. The term "database" is not intended to be limiting and is intended to include any suitable type of data structure, as would be clear to the skilled person.

In an alternative embodiment, the access point database is initially empty. The WiFi™ unit 118 is arranged to perform a scanning operation in order to detect new access points. This is a standard function of a WiFi™ device and is known to the person skilled in the art. The user sets up the mobile device 100 so that it either continuously scans for new access points, or scans for new access points when instructed by the user. In the latter case, the user may instruct the mobile device 100 to scan for an access point when the user knows that they are within a hotspot of that access point. In this case, the scan is arranged to progress for a predetermined length of time, for example five seconds. If no access point is located in this time, the scan is stopped by the processor unit 107. The scanning function is used to populate the access point database with entries for any new access points that are located, together with connection information and information concerning the position of the new access points. This process will be described in connection with Figure 9.

The process begins by initiating a scan. The processor unit 107 instructs WiFi™ unit 118 to perform a scan (step 801). This scan may be in response a user instruction for the mobile device 100 to conduct a continuous or single scan. When an access point is located by the WiFi™ unit 118 (step 802), the processor unit 107 scans the access point database and establishes whether or not the access point is already stored in the database (step 803). If the access point already has an entry in the database, the scan is stopped (step 804). The device 100 can then connect to the access point, or not, depending on the requirements of the user. If no entry exists for the new access point, the processor creates a new entry in the access point database (805). The entry includes information concerning the position or estimated position of the access point as well as connection parameters for the new access point. The processor unit 107 then stops the scan (step 806) and informs the user, via display 105, that a new access point has been located and stored.

In a further embodiment of the present invention, when an access point is located by the WiFi ™ unit 118, the position of the access point is estimated by the processor unit 107. Once the access point has been located, the GPS unit 117 is instructed by the processor unit 107 to establish the position of the mobile device 100. The processor unit 107 then enters this position as the position of the access point in the estimated position filed. Although the position of the access point and the position of the mobile device are normally not the same when this determination is made, for the purposes of the present invention this estimation enables the mobile device to operate satisfactorily when operating according to Figure 4.

In an alternative embodiment, once the GPS unit 117 has determined the position of the mobile device 100, the processor unit 107 estimates the range of the mobile device from the access point. This may be done by measuring the strength of the signal received by the mobile device 100 and comparing this with a comparison table (not shown) which contains predetermined estimates of range based on signal strength. The comparison table is stored in the storage device 116. The processor unit then makes a temporary record of this information. The processor unit 107 then waits a predetermined length of time before instructing the GPS unit 117 to calculate the position of the mobile device again. Assuming the device has moved, and is still in range of the access point, the processor unit 107 measures position and calculates range a second time and makes a temporary record of this information. Once this routine has been completed three times, the processor unit 107 runs a triangulation algorithm familiar to those skilled in the art to estimate the position of the access point. This estimated position is then recorded in the estimated position field.

In yet another embodiment, each access point maintains a record of its location. Once the mobile device 100 has connected to an access point the access point transfers its location information to the mobile device 100. The mobile device records this information in the exact position field in the access point database. In use, the exact position information is used, if present, instead of any estimated position information that may be stored.

In a further embodiment, a mobile device (not shown) is provided which includes all of the features of mobile device 100, except that the device does not include a GPS unit. In the following, the numbering of Figures 1 and 2 will be used to refer to elements of the mobile device of the present embodiment which are common with those of the mobile device 100. The mobile device of the present embodiment has no inbuilt mechanism for determining its location.

Other mechanisms exist which enable a user to establish their position. One such mechanism is Cell ID. Every base station in a mobile phone network has a unique Cell ID. This information can be communicated to each mobile device which is active within a particular cell. The location of each base station is known. The service provider therefore has information on the location of each base station as well as the Cell ID for each base station. This information may be stored in a database which can be used by the service provider to provide location based services. If a user wishes to know their location, the service provider can provide an approximate position based the Cell ID of the base station of the cell in which the mobile device is currently active. The details of Cell ID are not provided here as the technique is well known to those skilled in the art.

In the present embodiment, the mobile device does not actual need to know its geographical position. Instead, the mobile device simply needs to know if an access point is within a particular cell. In the present embodiment, the mobile device uses Cell ID in a different manner to that described above. Instead of associating the Cell ID with a geographical position, all that is required is that the Cell ID is associated with particular access points. This is described in more detail below.

The access point database includes fields for the Cell ID of the base station in which the access points are located, rather than the geographical position of each access point. In use, instead of polling a GPS unit, the processor unit 107 polls the Cell ID of the base station of the cell in which the device is active. This information may be obtained directly from the base station in a manner familiar to those skilled in the art. Rather than comparing the devices location with the access point database, the processor unit 107 compares the current Cell ID with the Cell IDs in the access point database. If an access point is located within the cell in question, the processor unit 107 updates the temporary register to indicate that an access point is within range.

The frequency at which the Cell ID comparison is carried out can be manually set or preset by the service provider. One advantage that Cell ID has over GPS is that the amount of battery power used when checking Cell ID is substantially lower than the amount of battery power used when polling the GPS unit. One of the aims of the present invention is to reduce power use. While occasional GPS use is more efficient that continuous WiFi™ scanning, GPS units still require power. However, the amount of power required to obtain Cell ID information is negligible. In this sense the use of Cell ID to determine if an access point is in range is essentially "power free". For this reason Cell ID comparisons can be made with a much higher frequency than is desirable when using GPS. Preferably, the check is carried out at least once a second. Alternatively, the comparison may be carried out on a continuous basis.

In the present embodiment, the mobile device does not require a range determination unit. If a particular cell has an access point in it, this is indicated in the access point database. If the user enters such a cell then the user is deemed to be within range of the access point in question.

In terms of the manner in which connections to the mobile phone network and access points is handled, the methods described above in relation to the GPS unit embodiment apply equally to the present embodiment. These methods will not be repeated here.

As with previous embodiments, the access point database may be preloaded with Cell IDs and access points. Alternatively, the database may be populated with entries as new access points are located as described above in relation to the first embodiment.

A cell can cover a relatively large geographical area and it is therefore possible that two or more access points are located within a given cell. If the

Cell ID comparison reveals that two access points are within range, this information can be stored in the temporary register. The device is arranged such that, if a user attempts to make a call, it will attempt to connect to one of the access points first. If that connection fails, it will attempt to connect to the other access point. If connection with other access points fails, the device is arranged to establish the call through the mobile phone network.

Cells in different countries may share the same Cell ID and cells within different networks may share the same cell ID . In view of this, the access point database may include MCC (Mobile Country Code) and MNC (Mobile Network Code) details for each cell in order to distinguish cells from different networks and countries.

In a further embodiment of the present invention, a mobile device may be provided with a GPS unit and with Cell ID functionality. The user can set up the device so that it uses these capabilities in whatever manner he/she decides. For example, the device could be set up so that GPS is always used in preference to Cell ID in order to take advantage of the better accuracy offered by GPS. If the GPS signals are too weak for the GPS unit to be able to obtain a position, the device will revert to using Cell ID. Alternatively, if battery power consumption is the main concern, the device can be set up to use Cell ID in preference to GPS.

A further embodiment of the present invention uses GSM timing information in conjunction with Cell ID in order to improve the accuracy of the system. Timing information can be used to more accurately determine a users location. The length of time it takes for timing signals to pass between a mobile device and a base station can be used to estimate the distance the device is from the base station. This information can be included within the access point database.

The phrase "information indicative of position" can refer to the actual, or estimated, geographical position of a particular device. Alternatively, this phrase can refer to information which is not geographical position information but is some other information which can be used to determine the relative location of a device. For example, in the above embodiments, Cell ID is used to determine whether or not a device is in the same cell as a WiFi™ hotspot. Cell ID is "information indicative of the position" of the device.

The phrase "predetermined notional range" can mean distance. If the geographical position of two devices are known, the distance between them can be calculated. However, in the above embodiment, geographical position is not known. When a device is determined to be within the same cell as a WiFi™ hotspot, it is assumed that the device is within range of the hotspot, although often, this will not be the case. In this case, the device and the WiFi™ hotspot are considered to be within, "predetermined notional range" of each other.

Various modifications, changes, and/or alterations may be made to the above described embodiments to provide further embodiments which use the underlying inventive concept, falling within the spirit and/or scope of the invention. Any such further embodiments are intended to be encompassed by the appended claims.

For example, as a modification to the above described embodiments, to provide a further embodiment, instead of using a satellite positioning system such as GPS to perform the location determinations, triangulation techniques can be used, as are already known in the art. More particularly, it is known for both GSM and UMTS networks that location determination can be performed using triangulation of the mobile devices position using signals received from the device at a plurality of mobile phone network base solutions, such position information can then be communicated back to the mobile device such that the device knows its position.

A further modification to the above embodiments provides an embodiment in which the user is given an option as to which network to connect to. For example, the user could configure the mobile device 100 such that, if the processor unit 107 determines that a mobile phone network and a WiFi™ network are available, rather than connecting to the WiFi™ network as a matter of course, the mobile device 100 could offer the user the choice as to which network the mobile device connects to. Thus, when a user tries to place a call, the mobile device 100 provides a visual or audible alert combined with on-screen instructions to choose a network. The user may then select either the mobile phone network or the WiFi™ network, depending on the importance of, for example, call cost, call mobility, connection quality, etc.

Claims

1. A mobile communications device, comprising: a first communication unit for connecting the device to access nodes of a first communications network; and a storage unit for storing a database of information indicative of the position of each of said access nodes; wherein the device is arranged to obtain information indicative of the position of the device; and the device is arranged to determine, based on said indicative position information, whether at least one of said nodes is within a predetermined notional range of said device.

2. A mobile device according to claim 1, wherein the first communications unit is arranged such that, in a first mode, it connects to an access node of said first communications network if said device determines that an access node is within said predetermined notional range.

3. A device according to claims 1 or 2, further comprising a second communications unit for connecting the device to access nodes of a second communications network.

4. A device according to claim 3, wherein said second communications unit is arranged such that, in said first mode, it connects to an access node of said second communications network if said device determines that none of said access nodes are within said predetermined notional range.

5. A device according to claims 3 or 4, wherein said second communications unit is a mobile phone radio transceiver.

6. A device according to claims 3, 4 or 5, further comprising a handover unit for handing over a connection from said first communications network to said second communications network, if the device moves to a position which is greater than said predetermined notional range from an access point.

7. A device according to claim 6, wherein said handover unit is also for handing over a connection from said second communications network to said first communications network, if the device moves to a position being less than said predetermined notional range from an access point.

8. A device according to claims 6 or 7, wherein said first communication unit is arranged to measure the quality of service of any connection established by it.

9. A device according to claim 8, wherein said handover unit is arranged such that handover from the first communication network to the second communication network is performed on the basis of said quality of service measurement.

10. A device according to any of claims 6 to 9, further comprising a first memory location for storing the time of a handover.

11. A device according to claim 10, wherein the handover unit is arranged to prevent handover within a predetermined time from the previous handover.

12. A device according to any preceding claim, wherein said information indicative of the position of an access node is the geographical position of an access node and the information indicative of the position of the device is the geographical position of the device.

13. A mobile device according to any claim 12, further comprising a positioning unit, wherein the positioning unit is arranged to determine said geographical position of the device.

14. A device according to any claim 13, wherein said positioning unit comprises a receiver for receiving radio positioning signals from a plurality of sources.

15. A device according to claim 14, wherein said radio positioning signals are used by the positioning unit to determine the geographical position of the device.

16. A device according to claim 15 wherein said radio positioning signals are generated by a global navigation satellite system.

17. A device according to any of claims 12 to 16, wherein said predetermined notional range is a predetermined distance.

18. A device according to any of claims 17, further comprising a range determination unit for determining whether at least one of said access nodes is within said predetermined distance of said device.

19. A device according to any of claims 3 to 11 wherein said information indicative of the position of each access node is information relating to the identity of at least one of said access nodes of said second communication network.

20. A device according to claim 19 wherein said information indicative of the position of the device is information relating to the identity of an access node of said second network.

21. A device according to claim 20, wherein said device is arranged to obtain said information relating to the identity of each access node of the second network from signals received via the second communication network.

22. A device according to claims 19 to 21 wherein said information relating to the identity of said access nodes of said second network is the Cell IDs of said access nodes.

23. A device according to claim 22, wherein said device determines that it is within said predetermined notional range of an access node of said first network if said Cell ID of an access node of the second network corresponds a Cell ID in said database.

24. A device according to any preceding claim wherein said first communications unit is a wireless local area network unit.

25. A device according to claim 24 wherein said first communications unit is a IEEE 802.11 unit.

26. A device according to any preceding claim, further comprising an alarm generator for generating an alarm when it is determined that the device is within notional range of an access point.

27. A mobile communications device, comprising a first communications unit for connecting the device to a first communications network, and a controller for enabling the first communications unit to connect to an access node of said network, if the device is determined to be within a predetermined notional range of at least one of said access nodes, wherein said determination is made by comparison between information indicative of the position of said at least one access point and information indicative of the position of the device.

28. A device according to claim 27, further comprising a second communications unit for connecting the device to a second communications network.

29. A device according to claim 28, wherein said information concerning position is geographical position.

30. A device according to claim 29, wherein said second communications network is arranged to determine the geographical position of the device, and transmit geographical position to the second communications unit.

31. A device according to claim 29, wherein the device is arranged to determine the geographical position of the device.

32. A device according to claim 31 , further comprising a radio positioning unit which is arranged to determine the geographical position of the device using radio positioning signals.

33. A device according to claim 30, wherein said controller is further arranged to determine the geographical position of the device using signals received via said second communication network.

34. A device according to any of claims 28 to 33, wherein said controller is also for enabling the second communications unit to connect to a base station of said second communications network, if the device is determined to be a distance greater than said predetermined range from at least one of said access nodes of said first communications network.

35. A device according to any of claims 27 to 34, wherein said first communications network is wireless local area network.

36. A device according to any of claims 27 to 35, wherein said second communications network is a mobile phone network.

37. A method for controlling access to a first communications network, the network comprising at least one access node, the method comprising: determining whether a mobile device is within a predetermined notional range of at least one of said access nodes by comparing information indicative of the position the device with information indicative of the position of said at least one access node.

38. A method according to claim 37, wherein said step of determining is performed in response to a user request for a connection.

39. A method according to claim 38, further comprising connecting the mobile device to said first communications network if it is determined that an access node is within said predetermined notional range.

40. A method according to claim 39, further comprising connecting the mobile device to an access node of a second communications network if it is determined that an access node of said first network is not within said predetermined notional range.

41. A method according to any of claims 37 to 40, wherein said step of determining is carried out at regular intervals.

42. A method according to claim 40, further comprising creating a temporary record of the result of said determination.

43. A method according to claim 42, further comprising checking said temporary record for said result of said determination in response to a user request for a connection, and connecting said mobile device to said first communications network if said result indicates that an access node is within said predetermined notional range.

44. A method according to claim 42, further comprising connecting said mobile device to an access node of a second communications network, if said result indicates that an access node of said first network is not within said predetermined notional range.

45. A method according to claims 39 or 43, further comprising handing over an established connection from said first network to said second network if said mobile device moves to a position at which it is not within said predetermined notional range from an access node of said first network.

46. A method according to claims 40 or 44, further comprising handing over an established connection from said second network to said first network if said mobile device moves within said predetermined notional range of an access node of said first network.

47. A method according to any of claims 37 to 46, wherein said step of determining further comprises a step of calculating the position of said mobile device.

48. A method according to claim 47, wherein said mobile device comprises a positioning unit and said step of calculating the position of said mobile device is performed by said positioning unit.

49. A method according to any of claims 37 to 48, wherein said position of said at least one access node is pre-stored on said mobile device.

50. A method according to any of claims 37 to 49, wherein the said step of determining comprises looking up an access range of an access point in a database.

51. A method according to any of claims 44 to 46, wherein said information indicative of the position of the device and said information indicative the position of said access nodes of the first communications network is information concerning the identity of an access node of the second communications network.

52. A method according to claim 51 , wherein said step of determining includes the step of comparing the identity of the access node of the second network, within which the device is currently active, with the identity of the access node of the second network, within which at least one of the access nodes of the first network are located.

53. A method of populating a database on a mobile communications device with details of a communication network's access nodes, comprising the steps of: scanning for available access nodes; obtaining information indicative of the position of the device if an access node is located; and storing details of the access node together with the information indicative of the position of the device at the time the access node was located.

54. A method according to claim 53, wherein said step of scanning is initiated by a user of said mobile device.

55. A method according to claim 541 , wherein said details of said access nodes are stored on said mobile device.

56. A computer program or suite of computer programs arranged such that when executed by a computer they cause the computer to operate in accordance with the method of any of claims 37 to 55.

57. A computer readable medium storing the computer program, or at least one of the suite of computer programs, according to claim 56.

58. An operating system for causing a computing device to operate in accordance with a method as claimed in any one of claims 37 to 55.