GB2500064A - Enabling a wireless communication unit to access cellular communication network services via an IP access network - Google Patents

Abstract

A wireless communication unit for use within a cellular communication network, the wireless communication unit comprising at least one signal processing module arranged to determine the presence of at least one Internet Protocol, IP, access network, issue a Home NodeB, HNB, registration request to at least one HNB gateway, HNB-GW, via the at least one IP access network, and establish an interface link between a virtual HNB entity within the wireless communication unit and the at least one HNB-GW upon receipt of an HNB registration success message

Description

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Title: A WIRELESS COMMUNICATION UNIT AND METHOD THEREFOR Description

5 Field of the invention

The field of this invention relates to a wireless communication unit and method therefor. The invention is applicable to, but not limited to, a wireless communication unit for use within a cellular communication network, and a method for enabling such a wireless communication unit to access cellular communication network services via an IP (Internet Protocol) access network.

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Background of the Invention

Wireless communication systems, such as the 3rd 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 3rd Generation 15 Partnership Project (3GPP™) (www.3app.org). The 3rd 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, 20 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 25 so-called lub interface.

Lower power (and therefore smaller coverage area) femto cells (or pico-cells) are a recent development within the field of wireless cellular communication systems. Femto cells or pico-cells (with the term femto cells being used hereafter to encompass pico-cells or similar) are effectively communication coverage areas supported by low power base stations (otherwise referred to as 30 Access Points (APs) of Home Node Bs (HNBs)). These femto cells are intended to be able to be piggy-backed onto the more widely used macro-cellular network and support communications to UEs in a restricted, for example 'in-building', environment.

Typical applications for such femto HNBs include, by way of example, residential and commercial (e.g. office) locations, communication 'hotspots', etc., whereby HNBs can be connected to 35 a core network via, for example, the Internet using a broadband connection or the like. In this manner, femto cells can be provided in a simple, scalable deployment in specific in-building locations where, for example, UEs may come into close proximity to a femto HNB.

In a conventional femto cell implementation, the femto cell allows a UE to connect to the core network using an IP (Internet Protocol) connection. Such IP connectivity between the femto HNB and

the core network is traditionally provided via a fixed-line broadband connection, such as a DSL (Digital Subscriber Line) connection. A more recent femto cell concept is to provide such IP connectivity via a wireless backhaul bridge, for example by way of a wireless local area network (WLAN) connection. In this manner, the femto HNB is able to be located away from the fixed line connection, and within any 5 point in range of the WLAN coverage.

In addition to the use of such wireless technology to provide a connection between the femto HNB and the core network, there are also proposals for WLAN offloading strategies using WLAN access technology in a 3GPP-based network. In this manner, the substantially redundant RF connection between a UE and an HNB with WLAN connectivity to the core network may be omitted, 10 enabling the UE to connect directly with the CN via a WLAN. A benefit of using WLAN or alternative IP access connectivity is the reduction in RF pollution to the 3GPP-based network, as well as the increased bandwidth typically available as compared with over a conventional 3GPP connection. Examples of such proposed WLAN offloading strategies include Interworked Wireless LAN (l-WLAN) which is described in 3GPP TS 24.327, and the Generic Access Network (GAN) (also known as 15 Unlicensed Mobile Access (UMA)) which is described in 3GPP technical specification TS 43.318.

I-WLAN is designed for packet switched services, enabling such services to be offloaded from the conventional 3GPP-based network connection to (where available) a WLAN access point. However, a disadvantage of the proposed l-WLAN technology is that it does not offer a seamless experience from an end-user perspective, particularly in terms of mobility at the radio layer, and voice-20 based services are treated as normal packet switched services with SIP (Session Initiation Protocol) messaging and without any specific treatment in terms of prioritisation or Quality of Service (QoS) measures. Furthermore, the deployment of l-WLAN requires the extension of existing infrastructure to include a new Packet Data Gateway (PDG) network component (physical or logical) with Tunnel Termination Gateway (TTG) functionality. An IMS (IP Multimedia Subsystem) core is also required to 25 support the different services including SIP-based voice services.

GAN uses GSM (Global System for Mobile Communications) or 3G signalling for voice calls regardless of whether access is available via a WLAN access point. The UMA agent in the mobile station ensures that, where available, a WLAN access point appears to the UE as a de facto 3GPP base station, whilst a GAN controller (GANC) in the 3GPP core network acts as a gateway between 30 the WLAN access point and the 3GPP core network with 3GPP standard interfaces with the core network elements. In this manner, the GAN technology enables a seamless experience to be provided to an end-user, with voice-based services being supported using conventional 3GPP signalling based on transporting the Radio Resource Control (RRC) protocol messages. However, the GAN technology still requires the extension of existing infrastructure to include the new GANC network 35 components.

Thus, a need exists for an improved method and apparatus for enabling a wireless communication unit to access cellular communication network services via an IP access network such as a WLAN.

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Summary of the invention

Accordingly, the invention seeks to mitigate, alleviate or eliminate one or more of the above mentioned disadvantages, either singly or in any combination. Aspects of the invention provide a wireless communication unit and a method therefor, as described in the appended claims.

5 According to a first aspect of the invention, there is provided a wireless communication unit for use within a cellular communication network. The wireless communication unit comprising at least one signal processing module arranged to determine a presence of at least one Internet Protocol (IP) access network, issue a Home NodeB (HNB) registration request to at least one HNB gateway (HNB-GW) via the at least one IP access network, and establish an interface link between a virtual HNB 10 entity within the wireless communication unit and the at least one HNB-GW upon receipt of an HNB registration success message.

In this manner, by establishing an interface link between a virtual HNB entity within the wireless communication unit and the at least one HNB-GW via the IP access network, the wireless communication unit is able to communicate with the cellular communication network substantially 15 directly via the IP access network. Accordingly, a substantially redundant RF connection between a wireless communication unit and an HNB with IP access network connectivity to the core network may be omitted. Furthermore, by providing a virtual HNB entity within the wireless communication unit that is registered with the HNB-GW, a connection is able to be established using existing UMTS femto cell infrastructure (e.g. an existing HNB-GW) substantially without any modification being required within 20 the core network or the radio network subsystem.

According to an optional feature of the invention, upon determining the presence of at least one IP access network, the signal processing module may be arranged to determine whether an HNB-GW is accessible via the at least one IP access network, and if it is determined that at least one HNB-GW is accessible via the at least one IP access network to issue the HNB registration request to the at 25 least one accessible HNB-GW. For example, the at least one signal processing module may be arranged to determine whether an HNB-GW is accessible by transmitting an access network query protocol (ANQP) query comprising at least one predefined address via the at least one IP access network. In this manner, the signal processing module(s) is able to detect whether an HNB-GW is accessible via an IP access network, and if so to request to register the virtual HNB entity. 30 According to an optional feature of the invention, the at least one signal processing module may be arranged to establish an Internet Protocol security, IPsec, tunnel between the wireless communication unit and a secure gateway, SeGW, of the HNB-GW.

According to an optional feature of the invention, when an interface link between the virtual HNB entity and the at least one HNB-GW has been established, the at least one signal processing 35 module may be further arranged to perform a cell (re)selection evaluation process comprising evaluating a suitability of the at least one IP access network for supporting communication between the wireless communication unit and the cellular communication network. In this manner, the signal processing module(s) is/are able to evaluate whether to select the IP access network/virtual HNB

entity as a (virtual) cell on which to move to, for example based on a comparative evaluation process used for evaluating cells within the cellular communication network.

According to an optional feature of the invention, when an interface link between the virtual HNB entity and the at least one HNB-GW has been established and when the wireless communication 5 unit is in a connected mode, the at least one signal processing may be further arranged to generate at least one measurement report comprising pseudo measurement data for the virtual HNB entity, and to send the measurement report comprising the pseudo measurement data for the virtual HNB entity to a serving base transceiver station. In this manner, the signal processing module(s) is/are able to present the WLAN/virtual HNB entity as a potential handover target to the cellular communication 10 network. Thus, and according to an optional feature of the invention, upon subsequent receipt of a handover request to the virtual HNB entity, the at least one signal processing module may be arranged to perform a hand-in of at least one service connection of the wireless communication unit to the virtual HNB entity.

According to an optional feature of the invention, the at least one signal processing module 15 may be arranged to receive data for transmission to the cellular communication network, and to translate the received data from a wireless communication unit/HNB interface format to an HNB/HNB-GW interface format. The at least one signal processing module may be further arranged to determine whether an HNB response is expected for the received data, and if it is determined that such a response is expected to generate and return an appropriate response from the virtual HNB 20 entity. The at least one signal processing module may be further arranged to determine whether the received data comprises HNB terminating data, and if it is determined that the received data comprises data that is not HNB terminating data to transmit the translated data to the HNB-GW, via the at least one IP access network.

In this manner, the particular communication medium used for connecting the wireless 25 communication unit to the core network, and thus for providing cellular communication network services such as voice, messaging and packet data services to the wireless communication unit is substantially transparent to applications and higher level communication protocol layers within the wireless communication unit, and to the HNB-GW.

In one optional feature of the present invention, the at least one signal processing module may 30 comprise:

- a UTRAN (Universal Terrestrial Radio Access Network) communication protocol stack component arranged to enable the transmission and reception of data over a UTRAN radio frequency, RF, interface;

- an IP access network communication protocol stack component arranged to enable the 35 transmission and reception of data over an IP access network interface; and

- a translation application component provided between the UTRAN communication protocol stack component and the IP access network communication protocol stack component, and arranged to perform a translation between a wireless communication unit/HNB interface format and an HNB/HNB-GW interface format.

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In one optional feature of the present invention, the at least one IP access network may comprise at least one from a group comprising at least one wireless IP access network and at least one wired IP access network. For example, the at least one IP access network may comprise a wireless local area network (WLAN).

5 According to a second aspect of the invention, there is provided a method for enabling a wireless communication unit to access cellular communication network services via an Internet Protocol (IP) access network. The method comprises, at the wireless communication unit, determining a presence of at least one IP access network, issuing a Home NodeB, HNB, registration request to at least one HNB gateway, HNB-GW, via the at least one IP access network, 10 and establishing an interface link between a virtual HNB entity within the wireless communication unit and the at least one HNB-GW upon receipt of an HNB registration success message.

In one optional feature of the present invention, the method may further comprise performing a cell (re)selection evaluation process comprising evaluating a suitability of the IP access network for supporting communication between the wireless communication unit and the cellular communication 15 network.

In one optional feature of the present invention, the method may further comprise when an interface link between the virtual HNB entity and the at least one HNB-GW has been established and when the wireless communication unit is in a connected mode:

- generating at least one measurement report comprising pseudo measurement data for the 20 virtual HNB entity; and

- sending the measurement report comprising the pseudo measurement data for the virtual HNB entity to a serving base transceiver station.

In one optional feature of the present invention, the method may further comprise receiving data for transmission to the cellular communication network, and translating the received data from a 25 wireless communication unit/HNB interface format to an HNB/HNB-GW interface format.

According to a third aspect of the invention, there is provided a non-transitory computer program product having executable program code stored therein for enabling a wireless communication unit to access cellular communication network services via an Internet Protocol (IP) access network. The program code operable for, at the wireless communication unit, determining a 30 presence of at least one IP access network, issuing a Home NodeB, HNB, registration request to at least one HNB gateway, HNB-GW, via the at least one IP access network, and establishing an interface link between a virtual HNB entity within the wireless communication unit and the at least one HNB-GW upon receipt of an HNB registration success message.

These and other aspects of the invention will be apparent from, and elucidated with reference 35 to, the embodiments described hereinafter.

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

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clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the respective drawings to ease understanding.

FIG. 1 illustrates a simplified example of part of a cellular communication system.

FIG. 2 illustrates a simplified block diagram of an example of part of a conventional 3GPP 5 HNB architecture for providing voice and data services to a wireless communication unit via an IP access network.

FIG. 3 illustrates a simplified block diagram of an example of part of a conventional UTRAN (Universal Terrestrial Radio Access Network) communication protocol stack component.

FIG. 4 illustrates a simplified block diagram of an example of part of an alternative architecture 10 for providing voice and data services to a wireless communication unit via an IP access network.

FIG's 5 and 6 illustrate simplified block diagrams of alternative examples of parts of communication protocol stack components.

FIG's 7 to 10 illustrate simplified flowcharts of parts of an example of a method for enabling a wireless communication unit to access at least one cellular communication network service via an IP 15 access network.

FIG. 11 illustrates a simplified block diagram of an example of a circuit-switched control plane architecture of a wireless communication unit.

FIG. 12 illustrates a simplified block diagram of an example of a packet-switched control plane architecture of a wireless communication unit.

20 FIG. 13 illustrates a simplified block diagram of an example of a circuit-switched user plane architecture of a wireless communication unit.

FIG. 14 illustrates a simplified block diagram of an example of a packet-switched user plane architecture of a wireless communication unit.

FIG. 15 illustrates an example of a simplified block diagram of a wireless communication unit. 25 FIG. 16 illustrates a typical computing system that may be employed to implement signal processing functionality in example embodiments.

Detailed Description

Examples of the invention will be described in terms of a wireless communication unit, or user 30 equipment (UE), within a 3rd generation (3G) Radio Network Sub-system (RNS) for supporting one or more femto cells within a Universal Mobile Telecommunications System (UMTS™) cellular communication network. However, it will be appreciated by a skilled artisan that the inventive concept herein described may be embodied in any type of wireless communication unit for use within a cellular communication network. In particular, it is contemplated that the inventive concept is not limited to 35 being implemented within a wireless communication unit for use within a UMTS cellular communication network, but may be equally applied within one or more wireless communication unit(s) adapted for use within any type of cellular communication system adapted in accordance with alternative cellular communication technologies.

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Moreover, the invention will be described in terms of an example of enabling a wireless communication unit to access at least one cellular communication network service via a WLAN, as exemplified by the IEEE 802.11 standard. However, it will be appreciated that the invention is not limited to enabling access to cellular communication network services via a WLAN, and may be 5 applied to embodiments enabling access to cellular communication network services via alternative IP (Internet Protocol) access networks, or similar data packet networks. In particular, the present invention is not limited to enabling access to cellular communication network services via wireless IP access networks, such as a WLAN, but may equally enable access to cellular communication network services via wired IP access networks, for example via a LAN, or via a fixed-line broadband 10 connection, such as a DSL (Digital Subscriber Line) connection.

Referring now to the drawings, and in particular FIG. 1, a simplified example of part of a cellular communication system is illustrated and indicated generally at 100. In FIG. 1, there is illustrated an example of a communication system in a form of a third generation partnership project (3GPP™) Universal Mobile Telecommunication System (UMTS™) network 100 that comprises a 15 combination of a macro cell 185 and a plurality of femto cells 150, 152. For the example embodiment illustrated in FIG. 1, radio network sub-systems (RNSs) comprise two distinct architectures to handle the respective macro cell and femto cell communications.

In the macro cell scenario, the RNS 110 comprises a controller in a form of a Radio Network Controller (RNC) 136 having, inter alia, one or more signal processing module(s) 138. The RNC 136 20 is operably coupled to at least one NodeB 124 for supporting communications within the macro cell 185. The NodeB 124 comprises signal processing module 126 and transceiver circuitry 128 arranged to enable communication with one or more wireless communication units located within the general vicinity of the macro communication cell 185, such as User Equipment (UE) 114. The RNC 136 is further operably coupled to a core network element 142, such as a serving general packet radio 25 system (GPRS) support node (SGSN) and/or a mobile switching centre (MSC), as known.

In a femto cell scenario, an RNS 112 comprises a femto access point, 130, also known as a Home NodeB (HNB), that is arranged to perform a number of functions generally associated with a cellular communication base station, and a controller in a form of a Home NodeB Gateway (HNB-GW) 140. As will be appreciated by a skilled artisan, an HNB is a communication element that supports 30 communications within a communication cell, such as a femto cell 150, and as such may provide access to a cellular communication network via the femto cell 150. One envisaged application is that an HNB 130 may be purchased by a member of the public and installed in their home. The HNB 130 may then be connected to an HNB-GW 140 via an luh interface 135, for example transported over, say, the owner's broadband internet connection (not shown).

35 Thus, an HNB 130 may be considered as encompassing a scalable, multi-channel, two-way communication device that may be provided within, say, residential and commercial (e.g. office) locations, communication 'hotspots' etc., to extend or improve upon network coverage within those locations. An example of a typical third generation (3G) HNB for use within a 3GPP™ system may comprise some NodeB functionality and some aspects of radio network controller (RNC) 136

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functionality. For the illustrated example embodiment, the HNB 130 comprises signal processing module 165 and transceiver circuitry 155 arranged to enable communication with one or more wireless communication units located within the general vicinity of the femto communication cell 150, such as User Equipment (UE) 114, via a wireless interface (Uu) 132.

5 The 3G HNB-GW 140 may be coupled to the core network (CN) 142 via an lu interface, such as the packet switched lu interface, lu-PS, and the circuit switched lu interface, lu-CS shown. In this manner, the HNB 130 is able to provide voice and data services to a cellular handset, such as UE 114, in a femto cell, in the same way as a conventional NodeB would in a macro cell, but with the deployment simplicity of, for example, a Wireless Local Area Network (WLAN) access point. In a 10 conventional femto cell implementation, the femto cell 150 allows a UE 114 to connect to the core network (CN) 142 using an IP (Internet Protocol) connection. Such IP connectivity between the femto HNB and the core network is traditionally provided via a fixed-line broadband connection, such as a DSL (Digital Subscriber Line) connection. A more recent femto cell concept is to provide such IP connectivity via a wireless backhaul bridge, for example by way of a wireless local area network 15 (WLAN) connection. In this manner, the femto HNB is able to be located away from the fixed line connection, and within any point in range of the WLAN coverage.

FIG. 2 illustrates a simplified block diagram of an example of such a conventional 3GPP HNB architecture for providing voice and data services to a UE 114 in a femto cell 150, via an IP access network. As illustrated in FIG. 2, the UE 114 is operably coupled to the HNB 130 via the UMTS air 20 interface (Uu) 132, which is implemented wirelessly by way of RF (radio frequency) signalling. The HNB 130 is in turn operably coupled to the HNB-GW via the luh interface 135, which is typically implemented over an IP (Internet Protocol) access network 210, such as via a user's broadband connection. The IP access network 210 may include a WLAN, for example comprising a WLAN access point 215 operably coupled to a fixed line connection, such as a DSL (Digital Subscriber Line) 25 connection. Access to the HNB-GW 140 is typically provided through a security gateway (SeGW) 220. The SeGW 220 establishes IPSec (Internet Protocol Security) tunnels with HNBs 130, via which all voice, messaging and packet data services between an HNB 130 and the core network 142 are delivered. As illustrated in FIG. 2, with such a conventional architecture, the UE 114 communicates with the core network 142 via RF signals over the Uu interface 132.

30 FIG. 3 illustrates a simplified block diagram of an example of part of a conventional UTRAN

(Universal Terrestrial Radio Access Network) communication protocol stack component 300 such as may be implemented within the signal processing module 118 of a UE 114, and arranged to enable the transmission and reception of data over the wireless interface (Uu) 132 to, in the example illustrated in FIG. 2, the HNB 130. The UTRAN communication protocol stack component 300 35 comprises a conventional UE UTRAN L2+ (data link) layer component 310 arranged to transfer data between the UE 114 and, say, the HNB 130. The UTRAN communication protocol stack component 300 further comprises a UTRAN PHY (physical) layer component 320 arranged to provide a procedural interface to the RF transmission medium, and a UTRAN RF layer component 330 arranged

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to perform the physical transmission and reception of RF signals between the UE 114 and (in this example) the HNB 130.

In accordance with some example embodiments of the present invention, the UE 114 may be further arranged to establish a substantially direct connection between itself and the core network 5 (CN) 142 via the IP access network 210 and the HNB-GW 140. For example, FIG. 4 illustrates a simplified block diagram of such an alternative architecture for providing voice and data services to a UE 114 via an IP access network. As illustrated in FIG. 4, the UE 114 is operably coupled directly to the IP access network 210 via the WLAN access point 215, which is implemented wirelessly by way RF signalling. Access to the HNB-GW 140 is again typically provided through a security gateway 10 (SeGW) 220, which establishes IPSec tunnels with, in this architecture, the UE 114 and via which all voice, messaging and packet data services between the UE 114 and the core network 142 are delivered using the luh interface. In this alternative architecture, the UE 114 communicates via RF signals over a WLAN interface (not shown). Such interfaces are well known in the art, for example as defined within the IEEE 802.11 standard incorporated herein by reference, and thus will not be 15 described in greater detail herein.

FIG. 5 illustrates a simplified block diagram of an example of part of an IP access network communication protocol stack component 500, such as may be implemented within the signal processing module 118 of a UE 114, and arranged to enable the transmission and reception of data (such data comprising voice, messaging and packet data, etc.) over an IP access network interface 20 to/from in the example illustrated in FIG. 5, the HNB-GW 140. In the illustrated example, the IP access communication protocol stack component 500 is in the form of a WLAN communication protocol stack component 500, and thus comprises a WLAN MAC (media access control) layer component 510, which is a sub-layer of the data link layer arranged to enable addressing and channel access control mechanisms for the IP access network 210. The WLAN communication protocol stack 25 component 500 further comprises a WLAN PHY layer component 520 arranged to provide a procedural interface to the RF transmission medium, and a WLAN RF layer component 530 arranged to perform the physical transmission and reception of RF signals between the UE 114 and (in this example) the HNB-GW 140. In order to enable voice, messaging and packet data services, conventionally provided to the UE 114 via the UTRAN Uu interface 132, to be provided via a WLAN 30 interface, a translation application component 540 is provided between the conventional UE UTRAN L2+ (data link) layer component 310 of the UE 114 and an HNB UTRAN L2+ component 550. The UE 114 is arranged to enable the transmission and reception of data to/from, in the illustrated example, the HNB-GW 140, with the translation application component 540 being arranged to perform a translation between relevant Uu interface data and messages and luh interface data and messages, 35 as described in greater detail below. In particular for the illustrated example, the translation application component 540 is responsible for the exchange of Uu-equivalent transmissions (control and user planes) between the HNB UTRAN L2+ and the UTRAN UE L2+ stacks. The translation application component 540 is also responsible for terminating certain messages on either sides and generating responses without the need to involve the stack on the other side. In this manner, the

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translation application component 540 and HNB UTRAN L2+ component 550 enable at least some HNB functionality to be implemented within the UE 114, and enable a 'virtual' HNB entity, illustrated generally at 545, to be established within the UE 114 with which the HNB-GW 140 is able to communicate.

5 The WLAN communication protocol stack component 500 further comprises a TCP/IP (link layer) component 560 provided between the HNB UTRAN L2+ component 550 and the WLAN MAC layer component 510, and arranged to implement the required protocols for the transmission and reception of data over the IP access network 210.

In this manner, the substantially redundant RF connection between a UE 114 and an HNB 10 130 with WLAN connectivity to the core network 142 may be omitted, enabling the UE 114 to connect directly with the core network 142 via a WLAN. A benefit of using IP access network connectivity is the reduction in RF pollution, as well as the increased bandwidth typically available as compared with over, say, a conventional 3GPP connection. Advantageously, by performing a translation between UE - HNB data and messages and HNB - HNB-GW data and messages in this manner, the particular 15 communication medium used for connecting the UE 114 to the core network, and thus for providing voice, messaging and packet data services to the UE 114 is substantially transparent to applications and communication layers higher up the protocol stack within the UE 114.

FIG. 6 illustrates a simplified block diagram of an example of part of a communication protocol stack component within the UE 114 comprising the components of the UTRAN communication 20 protocol stack component 300 and the components of, in the illustrated example, the WLAN communication protocol stack component 500. In this manner, the UE 114 is able to access voice, messaging and packet data services via an HNB 140 or NodeB 124 over a conventional UTRAN Uu interface 132, such as by way of the convention architecture illustrated in FIG. 2, and/or directly via an IP access network 210, as illustrated in FIG. 4, over a WLAN interface 215. A selection controller 610 25 is provided and arranged to selectively configure via which of the communication protocol stack components 300, 500 voice, messaging and packet data services are to be accessed, as described in greater detail below.

FIG's 7 to 10 illustrate simplified flowcharts of parts of an example of a method for enabling a 30 wireless communication unit, such as UE 114, to access at least one cellular communication network service via an IP access network, for example such as voice, messaging and packet data services. The method of FIG's 7 to 10 may be performed, at least partially, by the signal processing module 118 of the UE 114. For the example illustrated in FIG's 7 to 10, and hereinafter described, access to the cellular communication network service(s) is enabled via a WLAN connection. However, it will be 35 appreciated that the invention is not limited to enabling access to cellular communication network services via a WLAN, and it is contemplated that access to the cellular communication network service(s) may equally be enabled via alternative IP (Internet Protocol) access networks, or similar data packet networks. In particular, the present invention is not limited to enabling access to cellular communication network services via wireless IP access networks, such as a WLAN, but may equally

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enable access to cellular communication network services via wired IP access networks, for example via a LAN, or via a fixed-line broadband connection, such as a DSL (Digital Subscriber Line) connection.

Referring first to FIG. 7, there is illustrated a simplified flowchart 700 of a first part of the 5 method for enabling, in this example, the UE 114 to access cellular communication network services via a WLAN. This first part of the method starts at 710 with determining the presence of a WLAN. For example, a WLAN transceiver module of the UE 114 may detect a WLAN, and provide an indication of the detection of the WLAN to the signal processing module 118. Next, at 720, the method comprises establishing a connection with the WLAN and, assuming a successful connection to the WLAN (for 10 example dependent on security restrictions, encryption requirements, etc.), determining whether an HNB-GW 140 is accessible via the WLAN at 730. For example, the UE 114 may be provisioned with one or more predefined SeGW and/or HNB-GW addresses, and arranged to determine whether an HNB-GW 140 is accessible by transmitting an access network query protocol (ANQP) query comprising at least one of the predefined addresses via the WLAN. The signal processing module 15 118 may be arranged to transmit such an ANQP query comprising one of the predefined addresses selected based on, for example, location, macro PLMN (public land mobile network), etc. For completeness, WLAN technology is well known in the art, with most modern WLANs being based on the IEEE 802.11 standards, which are incorporated herein by reference.

If it is determined that no HNB-GW is accessible, this part of the method ends, at 780. 20 However, if it is determined that at least one HNB-GW 140 is accessible via the WLAN, the method moves on to 740 where an Internet Protocol security (IPsec) tunnel is established between the UE 114 and a SeGW 220 of the HNB-GW 140, for example between the HNB UTRAN L2+ component 550 illustrated in FIG's 5 and 6 and the HNB-GW 140. Typically this may require an appropriate authentication credential to be installed on the UE that is compatible with the SeGW. Next, at 750, an 25 HNBAP HNB registration request, such as described in 3GPP TS 25.467 and TS 25.469, is issued to the HNB-GW 140 via the IPsec tunnel, for example the HNBAP HNB registration request being issued by the HNB UTRAN L2+ component 550 on behalf of the virtual HNB entity 545 within the UE 114. This message and response identify the virtual HNB entity 545 and contain the necessary parameters for the virtual HNB entity 545 to communicate with the HNB-GW 140. If the HNB registration request 30 is successful, i.e. upon receipt of an HNB registration success message from the HNB-GW 140, via the IPsec tunnel over the WLAN, at 760, the method moves on to 770 where an interface link is established between the virtual HNB entity 545 within the UE 114 and the HNB-GW 140, such as the luh interface link illustrated at 135 in FIG. 4. By this method the virtual HNB entity 545 and HNB-GW 140 may exchange messages according to the luh protocol as described in 3GPP TS 25.467, TS 35 25.468 and TS 25.479. The method then ends, at 780.

In this manner, by establishing an interface link between the virtual HNB entity 545 within the UE 114 and the HNB-GW 140, a connection via which cellular communication network services may be provided is established substantially directly between the UE 114 and the core network 142 via the WLAN. Significantly, such a connection is able to be established using existing UMTS femto cell

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infrastructure (HNB-GW 140) substantially without any modification being required within the core network 132 or the radio network subsystem 112. Furthermore, by implementing such a virtual HNB entity 545 between the UE UTRAN L2+ data link layer component 310 and the HNB UTRAN L2+ data link layer component 550 of the UE 114 in this manner, the particular communication medium used for 5 connecting the UE 114 to the core network, and thus for providing voice, messaging and packet data services to the UE 114 is substantially transparent to applications and communication layers higher up the protocol stack within the UE 114, enabling a substantially seamless experience from an end-user perspective.

10 Referring next to FIG. 8, there is illustrated a simplified flowchart 800 of a further part of the example method for enabling, in this example, the UE 114 to access cellular communication network services via an IP access network, such as a WLAN. This further part of the method starts at 810, for example with the UE 114 in an idle mode, and moves on to 820 where a cell (re)selection evaluation process is performed. For example, as within a conventional UMTS cell (re)selection evaluation 15 process, the signal processing module 118 of the UE 114 may be arranged to search for a suitable cell on which to camp, or move to, with the aid of the UE's transceiver 116, by evaluating each cell based on, say, signal strength, signal quality, etc. of a PICH (paging indicator channel) and/or PCH (paging channel) of the cell in accordance with specific criteria, such as those defined in 3GPP technical specification TS 25.304. In accordance with some example embodiments of the present 20 invention, if a virtual HNB entity 545 has been established within the UE 114, the signal processing module 118 may be arranged to perform a similar evaluation process for the WLAN via which a connection with the HNB-GW 140 has been established. In this manner, a suitability of the WLAN for supporting communication between the wireless communication unit and the cellular communication network may be evaluated. In some examples, the criteria may include signal strength and quality, 25 operator preferences and user preferences. In some examples, the evaluation criteria for the WLAN may be more favourable towards the WLAN as compared with the evaluation criteria for the cellular communication network cells. It is contemplated that, in the case were access to cellular communication network services is provided via a wired IP access network, e.g. where the UE 114 is connected directly to a user's hardwired broadband connection, pseudo (favourable) data may be 30 used for the IP access network. In this manner, the UE 114 may be biased towards moving to, and camping on, the IP access network (e.g. the WLAN in the illustrated example) ahead of conventional cellular communication network cells.

Having performed the cell reselection evaluation process, if, at 830, it is determined that the UE 114 should camp on (move to) a cell within the cellular communications network, the method 35 moves on to 840 where the conventional procedure for camping on such a cellular communications network cell (e.g. a UMTS/GERAN cell) is performed, and the method ends at 860. However, if it is determined that the UE 114 should move to the WLAN, the method moves on to 850, where the UE 114 is registered with the virtual HNB entity 545 within the UE 114, for example by sending from the HNB UTRAN L2+ component 550 of the virtual HNB entity 545 an HNBAP UE registration request to

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the HNB-GW 140, and receiving in response a registration accept message as described in 3GPP TS 25.467. The method then ends, at 860.

Referring now to FIG. 9, there is illustrated a simplified flowchart 900 of a further part of the 5 example method for enabling, in this example, the UE 114 to access cellular communication network services via a WLAN. This further part of the method starts at 910, for example with the UE 114 in a connected mode. In particular, the UE 114 may comprise one or more active service connections with a cellular communications network cell (serving cell). The method then moves on to 920 where RF downlink measurements are performed for the serving cell and for neighbouring cells within the 10 cellular communications network. For example, as within a conventional UMTS network, the signal processing module 118 of the UE 114 may be arranged to perform RF downlink measurements for cells identified within a neighbour cell list broadcast by the serving cell. In accordance with some example embodiments of the present invention, if an luh interface link has been established between the virtual HNB entity 545 within the UE 114 and the HNB-GW 140, the signal processing module 118 15 may be arranged to perform similar RF downlink measurements for the WLAN via which the luh interface link with the HNB-GW 140 has been established. It is contemplated that, in the case were access to cellular communication network services is provided via a wired IP access network, e.g. where the UE 114 is connected directly to a user's hardwired broadband connection, pseudo (favourable) measurement data may be used for the IP access network.

20 Having performed the RF downlink measurements, the method moves on to 930 where a measurement report is generated. In the illustrated example, the measurement report is generated to comprise pseudo data for the virtual HNB entity 545; for example such pseudo data comprising positively biased RF measurement values in order to make the virtual HNB entity 545 appear more attractive from a handover perspective. Next, at 940, the measurement report is sent to the serving 25 cell. As is well known in the art, data contained within such measurement reports is typically used by, for example, the cellular communications network to determine whether a handover is required. Thus, by providing positively biased pseudo RF measurement data for the virtual HNB entity 545, the likelihood of the network deciding to perform a handover to the virtual HNB entity 545 is increased. The serving RNS may be configured so that certain neighbours in the neighbour list are interpreted as 30 referring to a HNB-GW thus enabling correct routing of handover requests.

Accordingly, in the illustrated example the method then moves on to 950 where a handover request to the virtual HNB entity 545 is received via the WLAN from, for example, an MSC within the cellular communications network. Next, at 960, the handover request is acknowledged, for example by the HNB UTRAN L2+ component 550 transmitting an acknowledgement message back to the 35 network from the virtual HNB entity 545 via the WLAN. A handover command to the UE 114 is then received, at 970, from the serving cell instructing the UE 114 to handover to the virtual HNB entity 545. A handover of one or more active service connection(s) is then performed from the serving cell to the virtual HNB entity 545 within the UE 114 such that the active service connection(s) are subsequently provided over the WLAN. A handover complete message is then sent from the virtual HNB entity 545,

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by the HNB UTRAN L2+ component 550, back to, in the illustrated example, the MSC via the WLAN, at 990, and the method ends at 995.

For such inbound mobility of the UE 114 to 'hand-in' to the virtual HNB entity 545, an HNB-Identity for the virtual HNB entity 545 to be used should allow the HNB-GW 140 to map to the IMSI 5 (International Mobile Subscriber Identity) of the UE 114. Including the IMSI of the UE 114 within HNB-Identity for the virtual HNB identity provided to the HNB-GW 140 is one option, although this would reveal the IMSI. TMSI (Temporary Mobile Scriber Identity) based techniques may also be used, such as disclosed in the technical specifications for Interworked Wireless LAN (l-WLAN) which is described in 3GPP TS 24.327, although this would require additional core network lookup from the HNB_GW 10 140. Accordingly, in order to support full handover of the UE 114 to the virtual HNB entity 545 therein, a minor modification to the HNB-GW 140 is necessary in order to enable the HNB-GW 140 to map the HNB-identity to, say, the IMSI and/or TMSI of the UE 114. However, such a modification may be avoided by not implementing such full handover functionality; for example by restricting the UE 114 from moving to the virtual HNB entity 545 therein when in idle mode.

15

Referring now to FIG. 10, there is illustrated a simplified flowchart 1000 of a further part of the example method for enabling, in this example, the UE 114 to access cellular communication network services via, in the illustrated example, a WLAN. This further part of the method starts at 1010, for example with the UE 114 in an idle mode, and moves to 1020 with the receipt of data for transmission 20 to the cellular communication network, such as would be transmitted over the UTRAN air interface (Uu interface) 132 in a conventional UMTS system. Such data may comprise, for example, data relating to voice, messaging and packet data services, measurement reports, control signalling, etc, and for the example illustrated in FIG's 5 and 6 is received by the by the UE UTRAN L2+ component 310, which applies the appropriate UE/HNB interface format to the received data for transferring the data between 25 the UE 114 and, say, an HNB 130 or Node B124. Next, at 1030, it is determined whether the UE 114 is camped on the virtual HNB entity 545; for example such a determination being made by the selection controller 610 illustrated in FIG. 6. If the UE 114 is not camped on the virtual HNB entity 545, the method moves on to 1040 where the received data is transmitted over the UTRAN air interface (Uu interface) 132 in a conventional manner, and the method ends at 1095. However, if it is 30 determined that the UE 114 is camped on the virtual HNB entity 545, the method moves on to 1050 where, the received data is translated from the UE/HNB interface format to an HNB/HNB-GW interface format typically used for transferring data between an HNB and an HNB-GW, i.e. from a Uu interface format to an luh interface format in the illustrated example. Next, at 1060, it is determined whether an HNB response is expected for the received data. If such a response is expected, an appropriate 35 response from the virtual HNB entity 545 is generated and returned, at 1070. In the illustrated example, it is also determined whether the received data comprises HNB terminating data, at 1080. If the received data does comprise HNB terminating data, the method ends, at 1095. Conversely, if the received data comprises data that is not HNB terminating data, the method moves on to 1090 where the translated data is transmitted to the HNB-GW 140, via the WLAN, and the method ends, at 1095.

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FIG's 11 to 14 illustrated simplified block diagrams of examples of control plane and user plane architectures for implementing the present invention within a wireless communication unit such as UE 114. In particular: FIG. 11 illustrates a simplified block diagram of an example of a circuit-5 switched control plane architecture; FIG. 12 illustrates a simplified block diagram of an example of a packet-switched control plane architecture; FIG. 13 illustrates a simplified block diagram of an example of a circuit-switched user plane architecture; and FIG. 14 illustrates a simplified block diagram of an example of a packet-switched user plane architecture.

10 Referring now to FIG. 15 for completeness, an example of a simplified block diagram of a wireless communication unit, such as UE 114, is shown. The example UE 114 contains at least one antenna 1502 coupled to the transceiver circuitry 116. More specifically for the illustrated example, the antenna 1502 is preferably coupled to a duplex filter or antenna switch 1504 that provides isolation between receive and transmit chains within the UE 114.

15 The receiver chain, as known in the art, includes receiver front-end circuitry 1506 (effectively providing reception, filtering and intermediate or base-band frequency conversion) arranged to enable data to be received from a base transceiver station within a cellular communication system, such as, for example, Node B 124 and/or HNB 130. The front-end circuitry 1506 is serially coupled to the signal processing module 118 (typically realised by a digital signal processor (DSP)). For example, 20 the signal processing module(s) 118 may be arranged to execute computer-readable code stored within one or more non-transitory computer program products, such as illustrated generally at 120, such computer-readable code being operable for performing the method of performing the verification of integrated circuit layouts.

As used herein, the expression non-transitory will be understood to refer to the non-ephemeral 25 nature of the storage medium itself rather than to a notion of how long the stored information itself may persist in a stored state. Accordingly, memories that might otherwise be viewed, for example, as being volatile (such as many electronically-erasable programmable read-only memories (EPROM's) or random-access memories (RAM's)) are nevertheless to be viewed here as being "non-transitory" whereas a signal carrier in transit is to be considered "transitory" notwithstanding that the signal may 30 remain in transit for a lengthy period of time. Accordingly, it is contemplated that such non-transitory computer program products 114 may comprise, by way of example only, at least one of a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, ROM, a Programmable Read Only Memory, PROM, an Erasable Programmable Read Only Memory EPROM, EPROM, an Electrically Erasable Programmable Read Only Memory, EEPROM, and a Flash memory. 35 An output from the signal processing logic 118 may be provided to a user-interface 1510,

which may comprise a display, loudspeaker, etc.

The controller 1514 is also coupled to the receiver front-end circuitry 1506 and the signal processing module 118. The controller 1514 and signal processing module 118 are also coupled to at

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least one memory device 1516 that selectively stores operating regimes, such as decoding/encoding functions, synchronisation patterns, code sequences, event measurement report data and the like.

As regards the transmit chain, this includes transmitter/modulation circuitry 1522 and a power amplifier 1524 coupled in series through to the antenna 1502. The transmitter/modulation circuitry 5 1522 and the power amplifier 1524 are operationally responsive to the controller 1514, and as such are used in transmitting data to a base transceiver station within a cellular communication system, such as, for example, Node B 124 and/or HNB 130.

In accordance with some examples, the UE may further comprise additional transceiver circuitry, illustrated generally at 1550, operably coupled to an additional antenna 1552. This additional 10 transceiver circuitry 1550 may components analogous to those of transceiver circuitry 116, but arranged to enable the transmission and reception of data over a WLAN.

The signal processor module 118 in the transmit chain may be implemented as distinct from the processor function in the receive chain. Alternatively, a single processor may be used to implement processing of both transmit and receive signals, as shown in FIG. 15. Clearly, the various 15 components within the UE 114 can be realised in discrete or integrated component form, with an ultimate structure therefore being merely an application-specific or design selection.

In accordance with examples of the invention, the memory device 1516 stores computer-readable code thereon for programming the signal processing module 118 to perform a method for enabling a wireless communication unit to access at least one cellular communication network service 20 via a WLAN.

Referring now to FIG. 16, there is illustrated a typical computing system 1600 that may be employed to implement signal processing functionality in embodiments of the invention. Computing systems of this type may be used in, by way of example, wireless communication units. Those skilled 25 in the relevant art will also recognize how to implement the invention using other computer systems or architectures. Computing system 1600 may represent, for example, 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. Computing system 1600 can include one or more processors, 30 such as a processor 1604. Processor 1604 can be implemented using a general or special-purpose processing engine such as, for example, a microprocessor, microcontroller or other control module. In this example, processor 1604 is connected to a bus 1602 or other communications medium.

Computing system 1600 can also include a main memory 1608, such as random access memory (RAM) or other dynamic memory, for storing information and instructions to be executed by 35 processor 1604. Main memory 1608 also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor 1604. Computing system 1600 may likewise include a read only memory (ROM) or other static storage device coupled to bus 1602 for storing static information and instructions for processor 1604.

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The computing system 1600 may also include information storage system 1610, which may include, for example, a media drive 1612 and a removable storage interface 1620. The media drive 1612 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 5 digital video drive (DVD) read or write drive (R or RW), or other removable or fixed media drive. Storage media 1618 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 1612. As these examples illustrate, the storage media 1618 may include a computer-readable storage medium having particular computer software or data stored therein.

10 In alternative embodiments, information storage system 1610 may include other similar components for allowing computer programs or other instructions or data to be loaded into computing system 1600. Such components may include, for example, a removable storage unit 1622 and an interface 1620, 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 15 storage units 1622 and interfaces 1620 that allow software and data to be transferred from the removable storage unit 1618 to computing system 1600.

Computing system 1600 can also include a communications interface 1624. Communications interface 1624 can be used to allow software and data to be transferred between computing system 1600 and external devices. Examples of communications interface 1624 can include a modem, a 20 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 communications interface 1624 are in the form of signals which can be electronic, electromagnetic, and optical or other signals capable of being received by communications interface 1624. These signals are provided to communications interface 1624 via a channel 1628. This 25 channel 1628 may carry signals and may be implemented using a wireless medium, wire or cable, fiber optics, or other communications medium. Some examples of a channel include a phone line, a cellular phone link, an RF link, a network interface, a local or wide area network, and other communications channels.

In this document, the terms 'computer program product', 'computer-readable medium' and the 30 like may be used generally to refer to non-transitory media such as, for example, memory 1608, storage device 1618, or storage unit 1622. These and other forms of computer-readable media may store one or more instructions for use by processor 1604, 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 35 system 1600 to perform functions of embodiments of the present invention. Note that the code may directly cause the 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.

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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 1600 using, for example, removable storage drive 1622, drive 1612 or communications interface 1624. The control module (in this example, software instructions or executable computer program code), when executed by the 5 processor 1604, causes the processor 1604 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 wireless communication unit. It is further envisaged that, for example, 10 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 signal processing module. However, the 15 inventive concept may equally be implemented by way of a plurality of different functional units and processors to provide the signal processing functionality. Accordingly, it will be understood that the term 'signal processing module' used herein is intended to encompass one or more signal processing functional units, circuits and/or processors. 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 20 a strict logical or physical structure or organization.

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 25 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 30 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 35 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

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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 5 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.

Thus, an improved method and apparatus for enabling wireless communication unit to access at least one cellular communication network service via an IP access network have been described, 10 wherein the aforementioned disadvantages with prior art arrangements have been substantially alleviated.

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Claims (19)

Claims 10

1. A wireless communication unit for use within a cellular communication network; the wireless communication unit comprising at least one signal processing module arranged to:

determine a presence of at least one Internet Protocol, IP, access network;

issue a Home NodeB, HNB, registration request to at least one HNB gateway, HNB-GW, via the at least one IP access network; and establish an interface link between a virtual HNB entity within the wireless communication unit and the at least one HNB-GW upon receipt of an HNB registration success message.

2. The wireless communication unit of Claim 1 wherein, upon determining the presence of at least one IP access network, the signal processing module is arranged to determine whether an HNB-GW is accessible via the at least one IP access network, and if it is determined that at least one HNB-GW is accessible via the at least one IP access network to issue the HNB registration

15 request to the at least one accessible HNB-GW.

3. The wireless communication unit of Claim 2 wherein the at least one signal processing module is arranged to determine whether an HNB-GW is accessible by transmitting an access network query protocol, ANQP, query comprising at least one predefined address via the at least

20 one IP access network.

4. The wireless communication unit of any one of the preceding Claims wherein the at least one signal processing module is arranged to establish an Internet Protocol security, IPsec, tunnel between the wireless communication unit and a secure gateway, SeGW, of the HNB-GW.

25

5. The wireless communication unit of any one of the preceding Claims wherein, when an interface link between the virtual HNB entity and the at least one HNB-GW has been established, the at least one signal processing module is further arranged to perform a cell (re)selection evaluation process comprising evaluating a suitability of the at least one IP access network for

30 supporting communication between the wireless communication unit and the cellular communication network.

6. The wireless communication unit of any one of the preceding Claims wherein, when an interface link between the virtual HNB entity and the at least one HNB-GW has been established 35 and when the wireless communication unit is in a connected mode, the at least one signal processing is further arranged to generate at least one measurement report comprising pseudo measurement data for the virtual HNB entity, and to send the measurement report comprising the pseudo measurement data for the virtual HNB entity to a serving base transceiver station.

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7. The wireless communication unit of Claim 6 wherein, upon subsequent receipt of a handover request to the virtual HNB entity, the at least one signal processing module is arranged to perform a hand-in of at least one service connection of the wireless communication unit to the virtual HNB entity.

5

8. The wireless communication unit of any one of the preceding Claims wherein the at least one signal processing module is arranged to receive data for transmission to the cellular communication network, and to translate the received data from a wireless communication unit/HNB interface format to an HNB/HNB-GW interface format.

10

9. The wireless communication unit or Claim 8 wherein the at least one signal processing module is further arranged to determine whether an HNB response is expected for the received data, and if it is determined that such a response is expected to generate and return an appropriate response from the virtual HNB entity.

15

10. The wireless communication unit of Claim 8 or Claim 9 wherein the at least one signal processing module is further arranged to determined whether the received data comprises HNB terminating data, and if it is determined that the received data comprises data that is not HNB terminating data to transmit the translated data to the HNB-GW, via the at least one IP access

20 network.

11. The wireless communication unit of any preceding Claim wherein the at least one signal processing module comprises:

a UTRAN (Universal Terrestrial Radio Access Network) communication protocol stack 25 component arranged to enable the transmission and reception of data over a UTRAN radio frequency, RF, interface;

an IP access network communication protocol stack component arranged to enable the transmission and reception of data over an IP access network interface; and a translation application component provided between the UTRAN communication protocol 30 stack component and the IP access network communication protocol stack component, and arranged to perform a translation between a wireless communication unit/HNB interface format and an HNB/HNB-GW interface format.

12. The wireless communication unit of any preceding Claim wherein the at least one IP access 35 network comprises at least one from a group comprising at least one wireless IP access network and at least one wired IP access network.

13. The wireless communication unit of Claim 12 where the at least one IP access network comprises a wireless local area network (WLAN).

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14. A method for enabling a wireless communication unit to access cellular communication network services via an Internet Protocol, IP, access network; the method comprising, at the wireless communication unit:

5 determining a presence of at least one IP access network;

issuing a Home NodeB, HNB, registration request to at least one HNB gateway, HNB-GW, via the at least one IP access network; and establishing an interface link between a virtual HNB entity within the wireless communication unit and the at least one HNB-GW upon receipt of an HNB registration success 10 message.

15. The method of Claim 14 wherein the method further comprises performing a cell (re)selection evaluation process comprising evaluating a suitability of the IP access network for supporting communication between the wireless communication unit and the cellular

15 communication network.

16. The method of Claim 14 or Claim 15 wherein the method further comprises, when an interface link between the virtual HNB entity and the at least one HNB-GW has been established and when the wireless communication unit is in a connected mode:

20 generating at least one measurement report comprising pseudo measurement data for the virtual HNB entity; and sending the measurement report comprising the pseudo measurement data for the virtual HNB entity to a serving base transceiver station.

25

17. The method of any one of Claims 14 to 16 wherein the method further comprises receiving data for transmission to the cellular communication network, and translating the received data from a wireless communication unit/HNB interface format to an HNB/HNB-GW interface format.

18. A non-transitory computer program product having executable program code stored therein 30 for enabling a wireless communication unit to access cellular communication network services via an Internet Protocol, IP, access network, the program code operable for, at the wireless communication unit:

determining a presence of at least one IP access network;

issuing a Home NodeB, HNB, registration request to at least one HNB gateway, HNB-GW, 35 via the at least one IP access network; and establishing an interface link between a virtual HNB entity within the wireless communication unit and the at least one HNB-GW upon receipt of an HNB registration success message.

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19. The non-transitory computer program product of Claim 18 wherein the non-transitory computer program product comprises 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, ROM, a Programmable Read Only Memory, PROM, an Erasable Programmable Read Only Memory, 5 EPROM, an Electrically Erasable Programmable Read Only Memory, EEPROM, and a Flash memory.