GB2498527A - Selecting a carrier frequency and scrambling code pair for an Access Point - Google Patents

Abstract

An access point (AP) or Home Node B (HNB) associated with a femto or pico cell, needs to select a carrier frequency and scrambling code pair to allow it to provision communication within a cellular network. The AP has at least one neighbouring AP or base station and is arranged to receive (320) a set of allowable cell physical layer access parameter(s) (i.e. carrier frequency and scrambling code pairs) from a system management entity, and to obtain (340) from each of the neighbouring cells their physical layer access parameter(s). From these parameters, an available subset of cell physical layer access parameter(s) is identified (360). From the identified subset an access parameter is selected (380) for the AP. By selecting a same parameter as a neighbouring base station, the AP will then be visible to mobile devices during a hand off process. The AP may also select the parameters based on limiting interference with neighbouring cells.

Description

Title: NETWORK ELEMENT, INTEGRATED CIRCUIT, CELLULAR COMMUNICATION

SYSTEM AND METHOD FOR PROVISIONING

Description

S

Field of the invention

The field of this invention relates to a communication unit, an integrated circuit, a cellular communication system and a method therefor. The invention is applicable to, but not limited to, a communication unit and method therefor to provision communication units within a cellular communication system, and in particular for provisioning a communication system with a frequency and scrambling code pair.

Background of the Invention

Wireless communication systems, such as the 3 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 (UMTSTM), developed by the 3 Generation Partnership Project (3GPPTM) (www.3gpp.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 3GPPfM parlance) in order 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 communication system via a Radio Access Network (RAN). A wireless cellular communication system typically comprises a plurality of radio network subsystems, each radio network subsystem comprising one or more (coverage) cells to which UEs may attach', and thereby connect to the network. Each macro-cellular RAN 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.

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 Access Points (APs) or Home Node B's (HNB5)). These femto cells are intended to be able to co-deployed with 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 APs/HNBs include, by way of example, residential and commercial (e.g. office) locations, communication hotspots', etc., whereby APs/HNBs can be connected to 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 AP/HNB. Thus, femto APs/HNBs are intended to enhance the coverage of a UMTSTM Radio Access Network (RAN) within residential and/or private commercial environments, and it is planned that the number of femto HNBs in a macro cell may number thousands.

APs today are often provided with a set of frequency and scrambling codes from which the AP may select a particular frequency and scrambling code pair for its operation in its location. The AP S typically makes that selection based on measurements (using a downlink Network Listen' receiver) of the interference levels on each of the available carriers, and the signal levels on the available carrier and scrambling code pairs. In this manner, the AP is able to select a frequency and scrambling code pair to maximise the signal-to-noise ratio that the AR and the UEs it is supporting have in operation. In practice, it is preferable to provide the AP with a large selection of such carrier and scrambling code pairs so that it can select the best available pair in its local area.

For normal operation, all such carrier and scrambling code pairs are typically provided to the AP within the re-selection list of (at least some of) the surrounding cells, especially the surrounding macro cells. This re-selection list is broadcast by a cell, and used by the UE to indicate those frequency and scrambling code pairs (together with threshold and other configuration information) it should be measuring when it is idle but camped on a cell in order to determine whether it would be better to re-select the cell camp onto which it should camp. However, macro-cell Network Operators typically manage macro cell Neighbour cell (Ncell) lists using a cell planning tool that models the propagation and, thus, signal strength of coverage from each cell, from which the possible neighbours for each cell can be determined from the list of cells which have coverage overlap with the cell considered. For APs it is not feasible to plan how their frequency and scrambling code selection affects the neighbour list of the macro-cells in this way, as their location is not known prior to installation, and such tools are not used to provide online configuration data to the APs. Further, for dense deployments of APs there may be many thousand APs within the coverage area of a macro cell, and these APs are required to reuse a small set of frequency and scrambling code pairs, which means that the macro cells in any given area each use common carrier and scrambling code pairs in each of their re-selection lists, and the AP is limited to identify possible carrier and scrambling code pairs for it to use by being configured with the same restricted set of frequency and scrambling code pairs.

There is a general desire in this field of technology to keep re-selection lists relatively small, in terms of a number of cells specified (as this dictates the time taken by user equipment (UEs) to scan for re-selection candidate cells/base stations), and in terms of the total message size used to transmit the re-selection list (as this dictates how much broadcast bandwidth the message takes). Thus, limits are often imposed on both the total number of communication cells that may be individually specified in the re-selection list, and as the number of cells in the list grows, so does the message size. These factors affect the re-selection lists for the Global System for Mobile communications (GSM)/GERAN communications standard and long term evolution (LTE) communications standard, but in particular the UMTSTM Terrestrial Radio Access Network (UTRAN) specifies a limit of three possible carrier frequencies to use (namely the serving carrier frequency plus two other carrier frequencies)).

Therefore, in practice, if there are three or fewer UTRAN carrier frequencies in use in any particular area, it is possible to include all neighbours in the re-selection list of all cells. Thus, when adding APs in a co-channel manner with these cells, they can be given primary scrambling code (PSC) options in each of the three or fewer carrier frequencies, and again all the options can be included in the re-selection lists of all macro cells (and of each other APs if re-selection between APs is desired as part of the Network Operator policy), provided the total number of neighbours or resulting total message S size remain within the operator's policy limits.

Network Operators typically control the list of UARFCN / Scrambling Codes (ScrCodes) that the third generation access point (3GAP) can pick from to be within the re-selection list transmitted by the macro cell. This re-selection list has to be provisioned based on an approximate location of the 3GAP and, thus, makes frequency planning for Network Operators when designing femto layers more complex to roll-out.

However, in areas of dense macro-cell reuse with a large number of carrier frequencies in use, the UTRAN re-selection list is explicitly limited to holding three carrier frequencies for the UEs to scan, by the 3GPP 25.133, the 3GPP UMTSTM specification, which states that the UE is only required to be capable of measuring signals from re-selection cells in the same carrier frequency as the serving cell and cells on up to two other frequencies. Hence, for example, if there are four or more carrier frequencies in use in a specific local area (macro cell environment), it is not possible for all the cells in that area to include all other local cells in the reselection lists, As a result, some APs have the option to use all (four or more of) the available carrier frequencies. In such a scenario, the AP may indeed not have available to it the least-used (and thus best from the AP's perspective) carrier frequency.

Typically, the femto AP is made to use one carrier frequency that is broadcast by the macro cell (and is often co-channel with the macro cell). Thus, as this carrier frequency is heavily used by the macro cell, the macro cell communications may heavily interfere with the AP communications. Furthermore, in using the carrier frequency employed in the macro cell, the AP can then cause pilot pollution' to the macro cell.

The carrier frequencies and specific primary scrambling codes (PSCs) of cells using those carrier frequencies that are included in the re-selection lists of macro cells are typically determined by applying the Network Operator's design policy (e.g. the Network Operator may use some cells in umbrella layers and some cells in more localised (often referred to as hot spot") layers. In some instances or Network Operator's design policies, UEs may prefer (or be allowed) to camp on the localised hot spot layers so that the macro cells handle as much of the call-based traffic as possible.

Alternatively, it may be the Network Operator's policy for the UEs to prefer to camp on the umbrella cells in order to minimise re-selection at the cost of increased setup and handover rates). In some instances or based on a Network Operator's design policy, cell planning tools may be used to determine the coverage areas of the macro cells, and thus identify those neighbouring cells that should be in the re-selection list.

Since the number of carrier frequencies that are in use varies geographically, with areas of dense usage having more carrier frequencies than areas of sparse usage, there are also boundaries that are typically configured between areas of three or fewer carriers and areas of four or more carrier frequencies. At these boundaries care needs to be taken to ensure that the combination of cell planning tool(s) and Network Operator policy(/ies) lead to acceptable UF behaviour.

If it is desired (as is commonly the case) that the AP can be reselected by a UE currently camped on a communication cell that is using any of these four or more carrier frequencies, it implies that the APs can use at most two carrier frequencies (as the re-selection lists of cells with which they are not co-channel may include only two other carrier frequencies). These two carrier frequencies that are usable in such a local area could be determined again using a cell planning tool, and this information made available to the AP based on its location (say determined by local global positioning system (GPS), subscriber address information or any other means). However, this implies a need for very accurate location information, and for a cell planning tool that is accurate to the size of the AR cell, as well as accurate with producing an indoor propagation model. Both of these criteria, individually or considered together, can be challenging, notwithstanding the challenges in constructing an integrated system that allows this information to go to the AP via the Operations and Management (OAM) system as it is deployed.

Thus, a need exists for provisioning communication units within a communication system with a frequency and scrambling code pair.

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 network element, a cellular communication system, a method and tangible computer product for provisioning communication units, as described in the appended claims.

These and other aspects 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 an example of part of a cellular communication system.

FIG. 2 illustrates an example of a simplified block diagram of a communication unit adapted to provision a communication unit within a communication system with a frequency and scrambling code pair.

FIG. 3 illustrates a simplified flowchart of a method for provisioning a communication unit within a communication system with a frequency and scrambling code pair.

FIG. 4 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 network element within a 3rd generation (3G) Radio Network Sub-system (RNS) for supporting one or more fernto cells within a Universal Mobile Telecommunications System (UMTSTM) 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 network element for supporting communications within a cellular communication network. In particular, it is contemplated that the inventive concept is not limited to being implemented within a network element for supporting one or more femto cells within a UMTSTM cellular communication network, but may be equally applied within one or more network element(s) adapted to support any type of communication cell, e.g. one or more macro cells, and/or adapted in accordance with alternative cellular communication technologies, which may employ the concept of broadcasting information about their neighbouring cells in order to assist their mobile stations to change their serving cell to a neighbour cell.

In particular, in some examples, the neighbour information that is broadcast may not be limited to frequency and scrambling code pairs as disclosed in one example embodiment of the invention, but may comprise any description, parameter, value or information element that the mobile station can use to initiate contact with that neighbour cell, and is typically a description of where to access the broadcast channel of that cell in terms of whatever the radio technology uses as the carrier description (e.g. a channel number in GSM, a frequency and Physical Cell Identifier in LIE).

Examples of the invention provide for a provisioning of communications, such as carrier frequency and scrambling code pairs, in order to ensure the AP selects a carrier and scrambling code pair that is in a re-selection list of (at least some) surrounding neighbours, whilst still allowing a wide choice of carrier frequency and scrambling code to the AP in order to minimise interference to/from its neighbouring cells. In particular, examples of the invention provide for a locally unique combination of carrier frequency and scrambling code, noting that at least a unique frequency is preferred as this interferes with neighbouring cells the least.

Examples of the invention describe a network element, an integrated circuit and a method for provisioning communication within at least one communication cell of a cellular communication network. The network element has at least one neighbouring network element and comprises a signal processing module arranged to receive a set of at least one allowable cell physical layer access parameter(s) from a system management entity; obtain, for a plurality of neighbour cells of the network element, each neighbour cell's physical layer access parameter(s); identify an available subset of the at least one allowable cell physical layer access parameter(s) from the plurality of neighbour cells' physical layer access parameter(s); and select allowable cell physical layer access parameter(s) from the identified available subset. In a number of applications, the communication unit may, in accordance with examples of the invention, more effectively select possible broadcast channel parameters for it to use within a cellular communication system.

In some examples, such as a UMTSTM implementation, the set of at least one allowable cell physical layer access parameter(s) may comprise at least one from a group comprising: a description, a parameter, a value, an information element that a mobile station communicable with the network element can use to initiate contact with that neighbour cell. In this example, the set of at least one allowable cell physical layer access parameter(s) may comprise a set of allowable frequency and scrambling codes. In this example, the at least one allowable cell physical layer access parameter(s) may comprise each neighbour cell's re-selection list.

Examples of the invention may alleviate a need for information (or the need for high accuracy in such information) from cell planning tools in order to correctly provision APs with allowable S frequency and scrambling code pairs. Examples of the invention may also provide APs with a larger set of possible frequency and scrambling code pairs, taken from any of multiple available frequencies that have been designated for AP deployments by the Network Operator in the frequency planning phase. Examples of the invention may also use cell planning and any associated network management policy in order to determine the re-selection neighbour lists (including at least some of the frequency and scrambling codes) to be provisioned into the macro cells. Examples of the invention may additionally use information about the re-selection lists of the actual neighbours of the APs (together with the Network Operator policy) in order to limit the APs to a subset of the provisioned allowable frequency and scrambling code pairs. In this scenario, the Network Operator may implement a policy as to how re-selection is to operate based on, say, how the carrier frequencies are used in different layers of the overall radio access network (RAN).

In the context of a third generation partnership project (3GPPTM) wireless communication system, a third generation access point (3GAP) is configured with frequency channels to scan as pad of a network listen (NWL) mode of operation. These scanning frequency channels are used to detect macro-cell neighbours and to decode their neighbour cell lists (Ncell lists) from the system information broadcast message (SIB11). The macro-cells are distinguished from other femto-cells by determining whether the detected cell's pilot channel transmit power (CPICH_TX_Power) is greater than a threshold. In accordance with some examples of the invention, the 3GAP is additionally configured with other possible frequencies and scrambling codes that it can use in operation. These other possible frequencies and scrambling codes may, in turn, be measured to derive the minimum interference level.

In accordance with some examples of the invention, the available sets of frequency/scrambling code pairs may be sub-divided into, for example, two lists: (i) those frequency/scrambling code pairs that are available if no macro-cell Ncell list is detected; and (ii) those frequency/scrambling code pairs that are available if the macro-cell Ncell list includes them. Thus, in some examples, the AP may select a least interfered with carrier to operate on based on the other possible frequencies and scrambling code pairs.

If the Ncell lists from the SIB1 1 message also appear in the frequency/scrambling code pairs that are available if the macro-cell Ncell list includes them, the identified frequency/scrambling code pairs may also be used in a frequency/scrambling code selection operation.

In accordance with some examples of the invention, the AP may also attempt to re-use the same frequency/scrambling code pairs, if possible, to avoid collision with other AP's that might be performing a scan at the same time and are not detected by one another.

In this manner, in accordance with some examples of the invention, a third generation access point (3GAP) may be able to choose more freely from the three available frequency carriers (based on, for example, a characteristic of least interference) but with an assurance that the frequency/scrambling code pair is in the macro-cell's (Ncell) list. In this manner, the Network Operator's management of Ncell lists may be eased and/or simplified. Furthermore, such an implementation may also allow the AP to operate on a least used' carrier frequency, which may therefore reduce pilot pollution to the macro cell and improve AP and Macro call drops and general S performance.

For clarity, the term neighbouring cell' used herein is intended to encompass communication cells that, for example, may be detected by a UE within the current cell; and the term is not intended to be restricted to immediately adjacent cells.

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 (3GPPTM) Universal Mobile Telecommunication System (UMTSTM) network 100 that comprises a 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 (RNS5) 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 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 system (GPRS) support node (SGSN) and/or a mobile switching centre (MSC).

In a femto cell scenario, an RNS 112 comprises an 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 previously mentioned, in some example embodiments, the number of femto HNBs in a single macro cell may number a few or tens of thousands. As will be appreciated by a skilled artisan, an HNB is a communication element that supports 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 implemented over, say, the owner's broadband internet connection (not shown).

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 3GPPTM system may comprise some NodeB functionality and some aspects of radio network controller (RNC) 136 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.

The 3G HNB-GW 140 may be coupled to the core network (ON) 142 via an lu interface, such as the packet switched lu interface, lu-PS, as 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.

The example cellular communication system 100 illustrated in FIG. 1, may comprise one or more network elements for supporting communication within one or more cells of the communication system 100, such as the femto HNB 130.

In accordance with some example embodiments of the present invention, a signal processing module within network element, such as signal processor 165 of HNB 130 of FIG. 1, is arranged to select a carrier frequency and scrambling code pair that resides in the re-selection list of (at least one or more) surrounding neighbours, whilst still allowing a wide choice of carrier and scrambling code to minimise interference. The carrier frequency and scrambling code pair are linked in that the AP is provisioned with permissible pairs, and the combination should be locally unique across all APs and other cells in the local area. The signal processing module 165 may be arranged to determine the neighbour lists of its surrounding cells using, for example, a network listen (NWL) receiver. In some examples, the signal processing module 165 may be arranged to determine the neighbour lists of its surrounding (non-closed access AP) cells as it may only wish to determine neighbour cell lists from closed access UEs in order to reselect to macro/non-AP cells.

In some examples, the signal processing module 165 may then be arranged to select one or more subset(s) of the neighbour cell lists that are identified as being held within its provisioned list of allowed carrier frequency/scrambling code pairs. The signal processing module 165 may then be arranged to perform a scan of allowed carrier frequency/scrambling code pairs signal and determine therefrom signal-to-interference levels on the selected subset of carrier frequency/scrambling code pairs in order to select the best of that subset (rather than of the whole provisioned set).

In this manner, the network element may be able to select the best available frequencies /primary scrambling code pair, say to minimise interference caused to/from macro-cell NodeBs, based on those local cells actually seen rather than an estimate of what would be seen based on geographic location, which might have to be a lot more conservative (i.e. include more neighbour cells than actual).

In some examples, one or more subsets of these available carrier and scrambling code pairs may be added to the re-selection lists of the macro cells (and potentially at other layers). In some examples, the one or more subsets may be selected at the design/provisioning stage, for example in order to enable APs to be deployed that can interact properly with macro-cells.

In some examples, the one or more subsets may be selected in accordance with one or more of the following: (I) selecting the one or more subsets that is/are on the same carrier(s) as existing re-selection neighbours (within the other layers). In this manner, and advantageously, no additional frequencies or new AR-specific scrambling codes need to be added to the re-selection lists, as the maximum number of frequencies is its own frequency plus an additional two other carrier frequencies; and (ii) adding one or more further subset carrier frequencies (and their associated scrambling codes) until the carrier frequency limit (of its own frequency plus an additional two other carrier frequencies) for the re-selection list is reached. In some examples, such new carriers may be added based on a commonality with at least one re-selection list(s) of at least one other macro-cell or femto-cell in the coverage area of the network elemenis/AP's cell, or alternatively adjacent to the AP's cell.

In some examples, if the subset of frequencies that are available on all surrounding cells is zero, thereby preventing the network element (AP) to select a frequency and scrambling code pair that is in the re-selection list of all neighbours, the signal processing module 165 may fall back to either a provisioned priority, or to selecting a frequency and scrambling code pair based on the subset of surrounding cells in a specific layer(s), for example as identified by power and/or frequency bands.

Alternatively, in other examples, if the network element (AP) is unable to detect any such neighbour cell(s) or is unable to receive their neighbour lists, the signal processing module 165 of the network element (AR) may request the subset from an entity within the management system that is managing the APs, for example having already provided that entity in the management system with what location information network element (AP) is able to (for example one or more of the following: information of other APs it can detect, information of other macros it is able to detect but cannot obtain their neighbour lists, GPS information, IP address information, etc.). Such information may be supplemented with information that the management system may already have (for example street address from subscriber/UE information or from a database) in order to select the correct neighbour subset from the entity's knowledge of macro cell locations and possibly their propagation information and their neighbour information (for example as learnt from other APs in the vicinity).

Referring now to FIG. 2 for completeness, an example of a simplified block diagram of a femto HNB 130 is shown. The example femto HNB 130 contains an antenna 202 coupled to the transceiver circuitry 155. More specifically for the illustrated example, the antenna 202 is preferably coupled to a duplex filter or antenna switch 204 that provides isolation between receive and transmit chains within the femto HNB 130.

The receiver chain, as known in the art, includes receiver front-end circuitry 206 (effectively providing reception, filtering and intermediate or base-band frequency conversion). The front-end circuitry 206 is serially coupled to the signal processing module 165. An output from the signal processing module 165 is provided to a transmit element of a network connection 210, for example operably coupling the signal processing module 165 to the HNB-GW 140 of FIG. 1 via, say, the Internet (not shown). The controller 214 is also coupled to the receiver front-end circuitry 206 and the signal processing module 165 (typically realised by a digital signal processor (DSP)). The controller 214 and signal processing module 165 are also coupled to at least one memory device 216 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 essentially includes a receiving element of a network connection 210, coupled in series through transmitter/modulation circuitry 222 and a power amplifier 224 to the antenna 202. The transmitter/modulation circuitry 222 and the power amplifier 224 are operationally responsive to the controller 214, and as such are used in transmitting data to a wireless communication unit, such as UE 118.

The signal processor module 165 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. 2. Clearly, the various components within the femto HNB 130 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 216 stores computer-readable code thereon for programming the signal processing module 165 to perform a method for enabling a reduction in inter-cell interference within a cellular communication system.

Referring now to FIG. 3 there is illustrated a simplified flowchart 300 of a method for provisioning communication units within a communication system with a frequency and scrambling code pair, for example as may be implemented within the signal processing module 165 of the HNB 130 of FIG's 1 and 2. The method of operation at the access point (AP), say AP 130 of FIG. 1 and FIG. 2, starts at 310, and moves on to 320 with the AP receiving a (relatively large) set of allowable frequency and scrambling codes from the management system, for example during a provisioning mode, together with information to configure the selection policy. In 330, the AP may then obtain a list of neighbour cells by any suitable means (for example by a Network Listen receiver, or by UE measurements, or by DAM provisioning, etc.). In 340, the AP obtains, for each neighbour, that neighbour's re-selection list by any suitable means (for example using a Network Listen receiver, or by DAM provisioning, or by information shared from other APs (as disclosed in a UK patent application filed concurrently by the Applicant with this application). In 350, the AP applies the configured policy to this information (which in one example may entail stipulating that the neighbour must be a neighbour of cells in band A, or must be a neighbour of cells with power levels greater than X', or with PSCs in a specified range) in order to determine those re-selection neighbour lists that it should consider.

In 360, the AP determines (identifies) the available subset of the allowable frequency and scrambling code pairs that it obtained in 320 and that are confirmed as being present in the neighbour re-selection lists from 340. The AP then determines whether an appropriate frequency and scrambling code pair is available from the identified subset in 370. If an appropriate frequency and scrambling code pair is available, in 370 the AP selects the appropriate frequency and scrambling code pair in 380 from the available subset (from 360) according to the configured policy of 350. In one example of the configured policy, the AP may select a frequency with a lowest total noise power and then select a comparable PSC with lowest specific noise power. If an appropriate frequency and scrambling code pair is not available, in 370, the AP may apply an alternative or further policy to be applied in 320 about how to then determine an available subset. For example, the AP may be configured to use a specific fixed subset to use in 360 or 380, or a different set of neighbours to consider in 350. The method then ends at 395.

S Referring now to FIG. 4, there is illustrated a typical computing system 400 that may be employed to implement signal processing functionality in embodiments of the invention. Computing systems of this type may be used in access points (HNBs), base transceiver stations and wireless communication units. Those skilled in the relevant art will also recognize how to implement the invention using other computer systems or architectures. Computing system 400 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 400 can include one or more processors, such as a processor 404. Processor 404 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 404 is connected to a bus 402 or other communications medium.

Computing system 400 can also include a main memory 408, such as random access memory (RAM) or other dynamic memory, for storing information and instructions to be executed by processor 404. Main memory 408 also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor 404. Computing system 400 may likewise include a read only memory (ROM) or other static storage device coupled to bus 402 for storing static information and instructions for processor 404.

The computing system 400 may also include information storage system 410, which may include, for example, a media drive 412 and a removable storage interface 420. The media drive 412 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 418 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 412. As these examples illustrate, the storage media 418 may include a computer-readable storage medium having particular computer software or data stored therein.

In alternative embodiments, information storage system 410 may include other similar components for allowing computer programs or other instructions or data to be loaded into computing system 400. Such components may include, for example, a removable storage unit 422 and an interface 420, 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 422 and interfaces 420 that allow software and data to be transferred from the removable storage unit 418 to computing system 400.

Computing system 400 can also include a communications interface 424. Communications interface 424 can be used to allow software and data to be transferred between computing system 400 and external devices. Examples of communications interface 424 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 communications interface 424 are in the form of signals which can be electronic, S electromagnetic, and optical or other signals capable of being received by communications interface 424. These signals are provided to communications interface 424 via a channel 428. This channel 428 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 produci, computer-readable medium' and the like may be used generally to refer to tangible media such as, for example, memory 408, storage device 418, or storage unit 422. These and other forms of computer-readable media may store one or more instructions for use by processor 404, 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 400 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.

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 400 using, for example, removable storage drive 422, drive 412 or communications interface 424. The control module (in this example, software instructions or executable computer program code), when executed by the processor 404, causes the processor 404 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) andfor 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 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 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 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 communication unit for provisioning a communication system with a frequency and scrambling code pair within a cellular communication system have been described, wherein the aforementioned disadvantages with prior art arrangements have been substantially alleviated.

Claims (1)

1. <claim-text>Claims 1. A network element for provisioning communication within at least one communication cell of a cellular communication network, wherein the network element has at least one neighbouring network element and comprises a signal processing module arranged to: receive (320) a set of at least one allowable cell physical layer access parameter(s) from a system management entity; obtain (340), for a plurality of neighbour cells of the network element, each neighbour cell's physical layer access parameter(s); identify (360) an available subset of the at least one allowable cell physical layer access parameter(s) from the plurality of neighbour cells' physical layer access parameter(s); and select (380) allowable cell physical layer access parameter(s) from the identified available subset.</claim-text> <claim-text>2. The network element of Claim 1 wherein the set of at least one allowable cell physical layer access parameter(s) comprises at least one from a group comprising: a description, a parameter, a value, an information element that a mobile station communicable with the network element can use to initiate contact with that neighbour cell.</claim-text> <claim-text>3. The network element of Claim 1 or Claim 2 wherein the set of at least one allowable cell physical layer access parameter(s) comprises a set of allowable frequency and scrambling codes.</claim-text> <claim-text>4. The network element of any preceding Claim wherein the at least one allowable cell physical layer access parameter(s) comprises each neighbour cell's re-selection list.</claim-text> <claim-text>5. The network element of any preceding Claim wherein the signal processing module is further arranged to: determine (350) from the plurality of neighbour cells' physical layer access parameter(s), based at least partly on a configured selection policy, a number of neighbour cells for consideration when identifying (360) an available subset; and select the appropriate at least one allowable cell physical layer access parameter(s) from the available subset based at least partly on the configured selection policy.</claim-text> <claim-text>6. The network element of Claim 5 when dependent upon Claim 3 wherein configured selection policy comprises selecting a frequency with a lowest total noise power and/or that creates least interference with the plurality of neighbour cells' and thereafter selecting a comparable scrambling code with lowest noise power.</claim-text> <claim-text>7. The network element of Claim 5 or Claim 6 wherein the signal processing module is arranged to receive information to configure the selection policy and the set of allowable physical layer access parameter(s) from a system management entity during a provisioning mode of operation.</claim-text> <claim-text>8. The network element of any preceding Claim wherein the signal processing module is arranged to sub-divide the available subsets of physical layer access parameter(s) into at least two sub-lists: (i) those physical layer access parameter(s) that are available if no macro-cell neighbour cell list is detected; and (ii) those physical layer access parameter(s) that are available if the macro-cell neighbour cell list includes the identified available subset of the allowable physical layer access parameter(s) from the plurality of neighbour cells' physical layer access parameter(s).</claim-text> <claim-text>9. The network element of any of preceding Claims 3 to 8 wherein the signal processing module is further arranged to add one or more further subset carrier frequency and associated scrambling code(s) until a carrier frequency limit for the re-selection list is reached.</claim-text> <claim-text>10. The network element of Claim 9 wherein the signal processing module is further arranged to add at least one new carrier frequency based on a commonality with the re-selection lists of at least one other macro-cell or femto-cell in a coverage area of, or adjacent to, the network element's cell.</claim-text> <claim-text>11. The network element of any preceding Claim wherein the signal processing module is further arranged to obtain (340) each neighbour cell's physical layer access parameter(s) for a plurality of neighbour cells of the network element via at least one from a group comprising: a Network Listen receiver, a user equipment measurement, Operations and Management provisioning.</claim-text> <claim-text>12. The network element of any preceding Claim wherein, in response to identifying (360) zero allowable physical layer access parameter(s) from the plurality of neighbour cells' physical layer access parameter(s), the signal processing module is arranged to apply an alternative selection policy in determining an available subset.</claim-text> <claim-text>13. An integrated circuit comprising the signal processing module of any preceding Claim.</claim-text> <claim-text>14. A method (300) for provisioning a communication unit in a wireless cellular communication system, the method comprising, at a network element having at least one neighbouring network element: receiving (320) a set of at least one allowable cell physical layer access parameter(s) from a system management entity; obtaining (340), for a plurality of neighbour cells of the network element, each neighbour cell's physical layer access parameter(s); identifying (360) an available subset of the at least one allowable cell physical layer access parameter(s) from the plurality of neighbour cells' physical layer access parameter(s); selecting (380) allowable cell physical layer access parameter(s) from the identified available subset.</claim-text> <claim-text>15. The method of Claim 14 wherein the set of at least one allowable cell physical layer access parameter(s) comprises at least one from a group comprising: a description, a parameter, a value, an information element that a mobile station communicable with the network element can use to initiate contact with that neighbour cell.</claim-text> <claim-text>16. The method of Claim 14 or Claim 15 wherein the set of at least one allowable cell physical layer access parameter(s) comprises a set of allowable frequency and scrambling codes.</claim-text> <claim-text>17. The method of any of preceding Claims 14 to 16 wherein the at least one allowable cell physical layer access parameter(s) comprises each neighbour cell's re-selection list.</claim-text> <claim-text>18. The method of any of preceding Claims 14 to 17 further comprising: determining (350) from the plurality of neighbour cells' physical layer access parameter(s), based at least partly on a configured selection policy, a number of neighbour cells for consideration when identifying (360) an available subset; and selecting the appropriate at least one allowable cell physical layer access parameter(s) from the available subset based at least partly on the configured selection policy.</claim-text> <claim-text>19. The method of Claim 18 when dependent upon Claim 16 wherein the configured selection policy comprises selecting a frequency with a lowest total noise power and/or that creates least interference with the plurality of neighbour cells' and thereafter selecting a comparable scrambling code with lowest noise power.</claim-text> <claim-text>20. The method of Claim 18 or Claim 19 wherein receiving (320) comprises receiving information to configure the selection policy and the set of allowable physical layer access parameter(s) from a system management entity is performed during a provisioning mode of operation.</claim-text> <claim-text>21. The method of any of preceding Claims 14 to 20 wherein available subsets of physical layer access parameter(s) are sub-divided into at least two sub-lists: (i) those physical layer access parameter(s) that are available if no macro-cell neighbour cell list is detected; and (ii) those physical layer access parameter(s) that are available if the macro-cell neighbour cell list includes the identified available subset of the allowable physical layer access parameter(s) from the plurality of neighbour cells' physical layer access parameter(s).</claim-text> <claim-text>22. The method of any of preceding Claims 16 to 21 further comprising adding one or more further subset carrier frequency and associated scrambling code(s) until a carrier frequency limit for the re-selection list is reached.</claim-text> <claim-text>23. The method of any of preceding Claims 14 to 22 wherein adding comprises adding at least one new carrier frequency based on a commonality with the re-selection lists of at least one other macro-cell or femto-cell in a coverage area of, or adjacent to, the network element's cell.</claim-text> <claim-text>24. The method of any of preceding Claims 14 to 23 wherein obtaining (340) each neighbour cell's physical layer access parameter(s for a plurality of neighbour cells of the network element, further comprises obtaining (330) a list of neighbour cells via at least one from a group comprising: a Network Listen receiver, a user equipment measurement, Operations and Management provisioning - 25. The method of any of preceding Claims 14 to 24 wherein obtaining that neighbour's physical layer access parameter(s) is performed using at least one from a group comprising: a Network Listen receiver, Operations and Management provisioning, information shared from at least one further network element.26. The method of any of preceding Claims 14 to 25 wherein, in response to identifying (360) zero allowable physical layer access parameter(s) from the plurality of neighbour cells' physical layer access parameter(s), the method further comprises applying an alternative selection policy in determining an available subset.27. A cellular communication system comprising a network element according to any of Claims ito 14.28. A tangible computer program product having executable program code stored therein for provisioning a communication unit in a wireless cellular communication system, the program code operable for, at a network element for performing the method of any of preceding Claims 14 to 26.29. The tangible computer program product of Claim 28 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.</claim-text>