EP2885943A1

EP2885943A1 - Network elements, cellular communication system and methods therefor

Info

Publication number: EP2885943A1
Application number: EP13739714.7A
Authority: EP
Inventors: Christopher Edward John Kilgour
Original assignee: IP Access Ltd
Current assignee: IP Access Ltd
Priority date: 2012-08-16
Filing date: 2013-07-23
Publication date: 2015-06-24
Also published as: GB201214622D0; GB2504978B; WO2014026830A1; GB2504978A

Abstract

A network element for supporting communication within at least one communication cell of a cellular communication network (100) includes a network listen receiver (107) for listening to broadcast messages of neighbouring cells and associated signal processing logic (105) for decoding the messages and extracting System Information/Packet System information therefrom. The decoded values can be used in a Network Assist Cell Change (NACC) operation for enabling a User Equipment (106) to reselect from a source cell to a target cell. Advantageously, the arrangement assists cell changes without interruption in data reception and without the need for Network Operators to employ a complex Radio Access Network Information Management (RIM) mechanism.

Description

NETWORK ELEMENTS, CELLULAR COMMUNICATION SYSTEM AND METHODS THEREFOR

Description Field of the invention

The field of this invention relates to network elements, a cellular communication system and methods therefor. The invention is applicable to, but not limited to, a network element for supporting communication within at least one cell of a cellular communication system, and a method for employing Broadcast messages therein.

Background of the Invention

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

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

Lower power (and therefore smaller coverage area) cells are currently referred to as 'small' cells, with the term femto cells typically reserved to refer to a residential small cell. Small cells are effectively communication coverage areas supported by low power base stations (otherwise referred to as Access Points (APs) with the term Home Node Bs (HNBs) identifying femto cell access points). These small cells are intended to augment the wide area macro network and support communications to UEs in a restricted, for example indoor, environment. An additional benefit of small cells is that they offload of traffic from the macro network to small cells, thereby freeing up valuable macro network resources.

Typical applications for such AP's include, by way of example, residential and commercial (e.g. office) locations, communication 'hotspots', etc., whereby HNBs can be connected to a core network via, for example, the Internet using a broadband connection or the like. In this manner, small cells can be provided in a simple, scalable deployment in specific in-building locations where, for example, network congestion at the macro-cell level may be problematic.

In small cells, it is proposed that small cell access points (APs) incorporate a downlink (DL) receiver radio sub-system, in a similar manner to a UE receiver, in order to wirelessly receive transmissions from other wireless serving communication units, such as NodeBs, other small cell AP's . It is also proposed that a small cell AP is able to scan for, receive, and decode transmissions from base stations, including macro cells and other small cells, in a manner that is termed Network Listen (NWL). Network Listen can operate with base stations belonging to the same network as the small cell AP, with base stations on the same or a different frequency band as the small cell AP, and with both 2G and 3G base stations.

Communications systems and networks are developing towards a broadband and mobile system. The 3rd Generation Partnership Project has proposed a Long Term Evolution (LTE) solution, namely, an Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, (E-UTRAN), for a mobile access network, and a System Architecture Evolution (SAE) solution, namely, an Evolved Packet Core ( EPC), for a mobile core network. The EPS network provides only packet switching (PS) domain data access so a voice service is provided by a 2G or 3G Radio Access Network (RAN) and circuit switched (CS) domain network. User Equipment^ UE) can access a CS domain core network through a 2G/3GRAN such as the (Enhanced Data Rate for GSM Evolution, EDGE) Radio Access Network (Radio Access Network, GERAN) or a Universal Mobile Telecommunication System Terrestrial Radio Access Network (Universal Mobile Telecommunication System Terrestrial Radio Access Network, UTRAN), and access the EPC through the E-UTRAN.

In a planned macro cell network, a so-called neighbour cell list is used to identify adjacent cells to each macro cell, to facilitate handover of UE communications between cells. The neighbour cell list is broadcast to roaming UEs by the network to enable the roaming UE to receive and assess the suitability of continuing a communication by transferring the communication to an adjacent (neighbour) cell. A UE receives the neighbour cell list in a radio resource control (RRC) system information broadcast message or by a specific UE message if it is in an active call. A neighbour cell list for a Node-B, for example (as configured at the RNC) is essentially a list of structures; with each structure containing a frequency and scrambling code to be used by the UE to access signals from every neighbour cell.

The UE measures the cells with the specified frequency and scrambling code to identify the best (generally closest) neighbouring macro cells to consider as potential target cells.

The UE then monitors neighbour cells and once one of them meets the specified criteria, the UE sends a Measurement Report to the RNC. Based on the information in the Measurement Report, the RNC determines whether to perform handover for the UE.

When handing over between cells in a GERAN system, one known method for ensuring packet switching mobility relies on the GERAN-capable User Equipment to control the handover process. It does this by monitoring System Information (SI) / Packet System Information (PSI) Broadcast messages from the target cell, prior to notifying the target cell of its arrival and subsequently requesting the packet data stream from the target cell. However, this method can lead to several seconds of interruption in user plane data reception. To overcome this problem, an alternative known method relies on assistance from the network, the so-called network assisted cell change (NACC). In this method, the source cell receives, from the target cell, the values of the relevant System Information / Packet System Information messages before handover takes place. The User Equipment is then provided with the values from the source cell just before handover which allows a quick start to registration and subsequent data reception in the target cell. Network assisted cell change was introduced by the 3GPP for GERAN- capable User Equipments in 3GPP Release 4. In 3GPP Release 5/6, this network assisted method was extended for handovers between cells which were operating in different Radio Access Networks, specifically cell changes from 2G to GERAN and 3G to GERAN. 3GPP Release 8 extended it further still for LTE to GERAN cell changes. Network Assisted Cell Change from UTRAN to GERAN is described in 3GPP TS 25.901. An External Network Assisted Cell Change is described in 3GPP TS 44.901.

However the NACC method creates the problem of getting the required System Information / Packet System Information from the target cell to the source cell and ensuring that it is accurate. This is particularly challenging in cases where the source and target cells are not attached to the same Base Station Controller. In these cases 3GPP proposed a solution known as the radio access network information management (RIM) mechanism. This requires that network elements, for example Base Station Controllers SGSN's (Serving GPRS support node) MME (mobility management entity), serving packet data, transparently route messages carrying the required information and associated control messages between a requesting element and the source cell. However, this method is complex and few network operators have employed it.

Thus there is a need for enabling system information values to be exchanged between cells, particularly cells which are attached to different base station controllers or operating on different Radio Access Networks. Hereinafter, the term "system information" shall be understood to include packet system information. Typically, system information may include repeat frequency, timing, reference frequency channel information, Random Access Channel (RACH) and Packet RACH (PRACH) control parameters for initiating access to the cell, Power Control Parameters, Control Channel format and organisation, frequency range, neighbour cell identities, neighbour cell frequencies, neighbour cell control and broadcast channel structure and information, NC mode (cell selection mode), Location Area Identities, DTX parameters for particular channels, parameters controlling cell reselection and hysteresis, support of GPRS, paging modes used, measurement order and control, Other information broadcast by a cell, include, the contents of System Information Message Type 1 , System Information Message Type 3, System Information Type 13 as defined in 3GPP TS 48.018 for transmission on the Broadcast Control Channel (BCCH) or the Packet System Information Message Type 1 , Packet System Information Message Type 2, Packet System Information Message Type 14 as defined in 3GPP TS 44.060 for a cell supporting the Packet Broadcast Control Channel (PBCCH). 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 network elements, a cellular communication system, and methods therefor, as described in the appended claims.

According to a first aspect of the invention, there is provided a network element for supporting mobility of a wireless communication unit between cells in a cellular communication system, the network element comprising a network listen receiver for receiving broadcast transmissions including system information transmitted by at least one wireless serving communication unit supporting a cell, signal processing logic arranged to extract system information included in said broadcast transmission and relevant for assisting relocation of a wireless communication unit from one cell to another, a store for storing said extracted system information, and a transmitter, for transmitting the stored, extracted system information to the wireless communication unit for enabling the wireless communication unit to relocate from one cell to another.

In this manner, the inventive concept provides an improvement to the use of Broadcast messages, which may be used to facilitate relocation (sometimes referred to as handover or reselection) from a source cell to a target cell in a cellular communication system which supports communication over both macrocells and fentocells (or any cell of small coverage area) and between cells operating on different Radio Access Networks..

Advantageously, it allows a Network Operator to avoid deploying Radio Access Network

Information Management (RIM) across their packet supporting network elements for the sole purpose of implementing Network Assisted Cell Change (NACC). Furthermore, it is easy to deploy in the case of multi-Radio Access Technologies and stacked cell sites.

The signal processing logic may be implemented in an integrated circuit device.

Extracted System Information may include repeat frequency, timing, reference frequency channel information, Random Access Channel (RACH) and Packet RACH (PRACH) control parameters for initiating access to the cell, Power Control Parameters, Control Channel format and organisation, frequency range, neighbour cell identities, neighbour cell frequencies, neighbour cell control and broadcast channel structure and information, NC mode (cell selection mode), Location Area Identities, DTX parameters for particular channels, parameters controlling cell reselection and hysteresis, support of GPRS, paging modes used, measurement order and control, Other information broadcast by a cell and which may be extracted by the signal processing logic, include, the contents of System Information Message Type 1 , System Information Message Type 3, System Information Type 13 as defined in 3GPP TS 48.018 for transmission on the Broadcast Control Channel (BCCH) or the Packet System Information Message Type 1 , Packet System Information Message Type 2, Packet System Information Message Type 14 as defined in 3GPP TS 44.060 for a cell supporting the Packet Broadcast Control Channel (PBCCH).

The invention is particularly useful for assisting handover (or relocation of a user equipment from a 3G cell to a 2G cell or from an LTE cell to a to 2G cell for a user equipment which supports NACC. The invention has the advantage that it can be employed with standard user equipment, ie.no modifications need to be made to the user equipment. According to an optional feature, the network element may be arranged to assist a handover or relocation of a user equipment from a source cell to a target neighbour cell, the target neighbour cell having been identified by the signal processing logic as being capable of supporting packet data flow transmission from broadcast messages received from the target neighbour cell by the receiver.

According to a further optional feature, the signal processing logic may be adapted to use measurements, made by the wireless communication unit, relating to a potential target neighbour cell, and reported to the network element, in addition to the received broadcast transmissions, in order to extract system information relevant for relocation to the potential target neighbour cell.

According to a second aspect of the invention, there is provided a method for supporting mobility of a wireless communication unit between cells in a cellular communication system, the method comprising; receiving at a network listen receiver, broadcast transmissions including system information transmitted by at least one wireless serving communication unit supporting a cell, extracting system information included in said broadcast transmission and relevant for assisting relocation of a wireless communication unit from one cell to another, storing said extracted system information, and transmitting the stored, extracted system information to the wireless communication unit for enabling the wireless communication unit to relocate from one cell to another.

According to a third aspect of the invention, there is provided a wireless communication system adapted to support mobility of a wireless communication unit between cells, the wireless communication system comprising; a network listen receiver for receiving broadcast transmissions including system information transmitted by at least one wireless serving communication unit supporting a cell, signal processing logic arranged to extract system information included in said broadcast transmission and relevant for assisting relocation of a wireless communication unit from one cell to another, a store for storing said extracted system information, and a transmitter, for transmitting the stored, extracted system information to the wireless communication unit for enabling the wireless communication unit to relocate from one cell to another.

The invention may find application in small cell systems, in which case, a network element in accordance with the first aspect of the invention may be incorporated into an Access Point.

The store may also be incorporated in the access point.

Alternatively, the store may be located remotely from the access point in another network module which is capable of communicating the extracted system information to and from the access point. In this alternative embodiment, several access points could contribute relevant system information broadcast from neighbouring cells to the central store. The central store could be conveniently located in a Home Note B Management System or a Home Note B, Gateway or a central control box in the enterprise operating the small cell system.

According to a fourth aspect of the invention there is provided a tangible computer program product. The tangible computer program product has executable program code stored therein for programming signal processing logic to perform a method for supporting mobility of a wireless communication unit between cells in a cellular communication system, the tangible computer program product comprising code for; receiving at a network listen receiver, broadcast transmissions including system information transmitted by at least one wireless serving communication unit supporting a cell, extracting system information included in said broadcast transmission and relevant for assisting relocation of a wireless communication unit from one cell to another, storing said extracted system information, and transmitting the stored, extracted system information to the wireless communication unit for enabling the wireless communication unit to relocate from one cell to another.

The tangible computer program product may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory

These and other aspects, features and advantages of the invention will be apparent from, and elucidated with reference 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 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 part of a cellular communication system operating in accordance with an example embodiment;

FIG. 2 is a simplified flow chart of an example of a method for supporting mobility of a wireless communication unit within a wireless communication system.

Detailed Description

The inventive concept finds particular applicability in a cellular communication system that supports a number of overlapping communication coverage areas, a communication system that comprises a combination of small cells and macro-cells and also one where more than one RAN is employed, e.g. 2G, 3G, LTE.

Referring now to Fig. 1 , an example of part of a wireless communication system, adapted in accordance with some embodiments of the invention, is illustrated and indicated generally at 100 and comprises a 3G small cell(cell A), a 2G macro-cell (cell B) and a LTE small cell (cell C). A core network of the wireless communication system of Fig. 1 includes a Gateway General

Packet Radio System (GPRS) Support Node (GGSN) 101 and a Serving GPRS Support Node (SGSN) 102. The GGSN101 or SGSN 102 is responsible for interfacing the wireless communication system 100 with a packet data network, for example a Public Switched Data Network (PSDN), (such as the Internet) or a Public Switched Telephone Network (PSTN). The SSGN 102 performs a routing and tunnelling function for traffic to and from the cells A, B and C while the GGSN 102 links with external packet networks. In an Evolved Packet Core, the equivalent node ito a GSGN is a Packet Gateway (P-GW) and in this example, the two are shown combined.

Small cell A is linked to the SGSN by way of lu-PS and luh links via a 3G Home Node B Gateway 103. The small cell A is served by a network element in the form of an Access Point(AP)/Home Node B 104 which includes a signal processing logic module 105. As will be appreciated by the skilled artisan, an access point 104 is a communication element that facilitates access to a communication network via a communication cell, such as a small cell. One application is that an AP 104 may be purchased by a member of the public and installed in their home. The AP 104 may then be connected to the HNB-GW 103 over the owner's broadband Internet connection. The AP 104 is typically provided with transmitting and receiving means for communicating wirelessly with a user equipment.

Thus, an AP 104 is a scalable, multi-channel, two-way communication device that may be provided within, say, residential and commercial (e.g. office) locations, 'hotspots' etc, to extend or improve upon network coverage within those locations. Although there are no standard criteria for the functional components of an AP, an example of a typical AP for use within a 3GPP 3G system may comprise Node-B functionality and some aspects of Radio Network Controller (RNC) functionality as specified in 3GPP TS 25.467. The AP 104 communicates with User Equipments (UE) such as UE 106 of Fig. 1 , via a wireless interface. The UE 106 supports Network Assisted Cell Change NACC

The AP 104, in accordance with an example of the invention, includes a network listen receiver 107. The output of this receiver 107 is connected to the signal processing logic module105, The 2G (GSM) macro-cell B is served by a Base Transceiver Station (BTS) 108 which is controlled by a Base Station Controller (BSC) 109. The BSC 109 is linked to the SGSN 102 and a Mobile Switching Centre 1 10.

Small cell C is linked to the SSGN 102 through a Mobility Management Entity (MME) 1 1 1. Small cell C is also connected with the GGSN 101 through the MME 102 and a switching Gateway 1 12. In a similar fashion to the 3G small cell A, the LTE small cell C is served by an Access Point 1 13 which incorporates a signal processing logic module 1 14. The Access Point 1 13 is provided with a network listen receiver 1 15.

In this particular example, the UE 106 is attached to small cell A and both small cells A and C are capable of listening to the broadcast channel of the 2G macro-cell B, which is transmitted by the BTS 108, by means of their network listen receivers 107, 1 15.

The broadcast transmissions from the BTS 108 contain system information relevant for handover/relocation purposes. For example, the System Information needed for assisting a handover from a HNB LTE in NACC handover is SIB 1 , 3 and 13 and PSI 1 ,2 and 14.

In this example, the AP 104 of cell A is supporting packet data communications with UE 106. The network listen receiver 107 is constantly listening to the broadcast transmissions of neighbouring cells particularly the 2G cell A in this example. The network listen receiver outputs the received signals to the signal processing logic module 105. The logic module 105 extracts the System Information contained within the broadcast signals which are relevant to handover/relocation and stores the information in an associated data store 1 16 along with the identity of the neighbour cell 108. The extracted System Information values are monitored ( by the logic module 105) for any changes over time and the store is updated accordingly The network listen receiver 1 15 of cell C may act in a similar fashion whereby its signal processing logic module 1 14 extracts relevant System Information and stores it in an associated store (not shown).

The stored System Information is used to pre-provision the UE 106 with the relevant information for assisting a NACC handover or relocation operation, eg. from 3G small cell A to 2G cell B or from LTE cell C to 2G cell B. A commonly used term for handover or relocation in the context of NACC is "reselection."

The UE 106 starts the reselection procedure. It requests reselection from its source cell A to a particular identified target cell, cell B in this example. The relevant System Information of this cell has been extracted by the logic module 105 from cell A's broadcast transmissions and stored in the store 1 16. During the reselection process, this information is extracted from the store 1 16 by the processing logic module 105 and transmitted from the AP 104 to the UE 106.

Hence, the UE is pre-provisioned with relevant System Information for reselection, therefore handover is done quickly, improving the user experience during cell change. The UE does not have to be modified in any way and the use of RIM is not required.

The relevant System Information for handover may be incorporated into the conventional Radio Resource Control RRC message which is sent, by the source cell (A) to the UE 106 for assisting with the handover. An example of such a message is the Cell Change Order from U-TRAN- TS 25.331. This has the advantage of improving the user experience during cell change.

In one optional embodiment, an Automatic Neighbour Relation process may be employed which allows cells to detect automatically their neighbours based on UE reports. The network listen receiver 107 might not have the same range as a UE so these UE measurement reports may be used to supplement the relevant System Information detected by the network listen receiver 107 and subsequently stored in the store 1 16.

Referring now to FIG. 2, there is illustrated a simplified flow chart 200 of an example of a method for supporting mobility of a wireless communication unit within a wireless communication system. The flow chart of FIG. 2 starts at 201 and moves to 202 where network listen results for NACC-relevant broadcast system data, which are obtained from one or more cells, are placed in a store. Subsequently at 203, a UE arrives on a source cell and registers for a packet switched domain. At 204, if the UE does not support NACC, then no further action can be taken but if it does, then the method moves to 205. At 205, the UE indicates to the network that it wishes to reselect to a target cell for which NACC is applicable (eg. GPRS (General Packet Radio Service)-enabled) and enters cell change (CCN) notification mode. .Next, at 206, at the source cell, the NACC System Information is obtained from the store. At 207, the source cell supplies the UE with the NACC information for the selected target cell. At 208, the UE is allowed to continue reselection to the target cell and at 209, the process ends.

Although the above embodiments of the invention describe a method and means to facilitate reselection from a small cell to a macro-cell, it is envisaged that the inventive concept is not restricted to such a reselection embodiment and reselection between other cell combinations are possible; for example, from any cell having a small coverage area to a nacro-cell and vice versa. Furthermore, although the example described above to with reference to Fig. 1 relates to listening to broadcast transmissions from a 2G cell, the invention can be implemented in other networks provided that the necessary RRC protocol modifications are made.

The signal processing functionality of the embodiments of the invention, particularly the signal processing logic modules105, 1 14 may be achieved using computing systems or architectures known to those who are skilled in the relevant art. Computing systems such as, a desktop, laptop or notebook computer, hand-held computing device (PDA, cell phone, palmtop, etc.), mainframe, server, client, or any other type of special or general purpose computing device as may be desirable or appropriate for a given application or environment can be used. The computing system can include one or more processors which can be implemented using a general or special-purpose processing engine such as, for example, a microprocessor, microcontroller or other control module.

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

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

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

The computing system can also include a communications interface. Such a communications interface can be used to allow software and data to be transferred between a computing system and external devices. Examples of communications interfaces can include a modem, a network interface (such as an Ethernet or other NIC card), a communications port (such as for example, a universal serial bus (USB) port), a PCMCIA slot and card, etc. Software and data transferred via a communications interface are in the form of signals which can be electronic, electromagnetic, and optical or other signals capable of being received by a communications interface medium.

In this document, the terms 'computer program product', 'computer-readable medium' and the like may be used generally to refer to tangible media such as, for example, a memory, storage device, or storage unit. These and other forms of computer-readable media may store one or more instructions for use by the processor comprising the computer system to cause the processor to perform specified operations. Such instructions, generally referred to as 'computer program code' (which may be grouped in the form of computer programs or other groupings), when executed, enable the computing system to perform functions of embodiments of the present invention. Note that the code may directly cause a processor to perform specified operations, be compiled to do so, and/or be combined with other software, hardware, and/or firmware elements (e.g., libraries for performing standard functions) to do so.

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

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

(ASIC) and/or any other sub-system element.

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

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

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term 'comprising' does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by, for example, a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Also, the inclusion of a feature in one category of claims does not imply a limitation to this category, but rather indicates that the feature is equally applicable to other claim categories, as appropriate.

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

Thus, an improved method and apparatus for facilitating a Network Assisted Cell Change within a cellular communication system have been described, wherein the aforementioned disadvantages with prior art arrangements have been substantially alleviated.

Claims

1. A network element for supporting mobility of a wireless communication unit (106) between cells in a cellular communication system (100), the network element comprising a network listen receiver (107) for receiving broadcast transmissions including System Information transmitted by at least one wireless serving communication unit (108) supporting a cell, signal processing logic (105) arranged to extract System Information included in said broadcast transmission and relevant for assisting relocation of a wireless communication unit (106) from one cell to another, a store (1 16) for storing said extracted System Information, and a transmitter (104) for transmitting the stored, extracted System Information to the wireless communication unit for enabling the wireless communication unit (106) to relocate from one cell to another.

2. The network element of claim 1 wherein the signal processing logic (105) is adapted to use measurements, made by the wireless communication unit (106) relating to a potential target neighbour cell, and reported to the network element, in addition to the received broadcast transmissions, in order to extract System Information relevant for relocation to the potential target neighbour cell.

3. The network element of either preceding claim wherein the signal processing logic (105) is implemented in an integrated circuit device.

4. A method for supporting mobility of a wireless communication unit (106) between cells in a cellular communication system (100), the method comprising; receiving at a network listen receiver, broadcast transmissions including System Information transmitted by at least one wireless serving communication unit (108) supporting a cell, extracting System Information included in said broadcast transmission and relevant for assisting relocation of a wireless communication unit (106) from one cell to another, storing said extracted System Information, and transmitting the stored, extracted System Information to the wireless communication unit (106) for enabling the wireless communication unit to relocate from one cell to another.

5. A wireless communication system (100) adapted to support mobility of a wireless communication unit (106) between cells, the wireless communication system comprising; a network listen receiver (107) for receiving broadcast transmissions including System Information transmitted by at least one wireless serving communication unit (108) supporting a cell, signal processing logic (105) arranged to extract System Information included in said broadcast transmission and relevant for assisting relocation of a wireless communication unit (106) from one cell to another, a store (1 16) for storing said extracted System Information, and a transmitter (104), for transmitting the stored, extracted System Information to the wireless communication unit (106) for enabling the wireless communication unit to relocate from one cell to another.

6. A tangible computer program product (105) having executable program code stored therein for programming signal processing logic to perform a method for supporting mobility of a wireless communication unit (106) between cells in a cellular communication system, the tangible computer program product comprising code for; receiving at a network listen receiver, broadcast transmissions including System Information transmitted by at least one wireless serving communication unit supporting a cell, extracting System Information included in said broadcast transmission and relevant for assisting relocation of a wireless communication unit from one cell to another, storing said extracted System Information, and transmitting the stored, extracted System Information to the wireless communication unit for enabling the wireless communication unit to relocate from one cell to another.

7. The tangible computer program product of Claim 6 wherein the tangible 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, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory.