EP2716100A1

EP2716100A1 - Reporting of neighbour femtocell information using automatic neighbour relation reports

Info

Publication number: EP2716100A1
Application number: EP12722165.3A
Authority: EP
Inventors: Hanns Juergen Schwarzbauer; Alexander Vesely; Karol Drazynski
Original assignee: Nokia Solutions and Networks Oy
Current assignee: Nokia Solutions and Networks Oy
Priority date: 2011-05-30
Filing date: 2012-05-23
Publication date: 2014-04-09

Abstract

A neighbour cell is measured at a subscriber station. The measured neighbour cell is reported to a first network node and the report of the measured neighbour cell is forwarded from the first network node to a control node. The neighbour cell report is sent from the control node to a second network node associated with the neighbour cell included in the measured neighbour cell report.

Description

DESCRIPTION

TITLE

REPORTING OF NEIGHBOUR FEMTOCELL INFORMATION USING AUTOMATIC NEIGHBOUR RELATION REPORTS

FIELD OF THE INVENTION

The invention generally relates to reporting of neighbour cell information. More particularly, the invention

relates to automated generation of neighbour cell

information for handover purposes in a mobile

communications network that includes femto cells.

BACKGROUND OF THE INVENTION

Femto cells are small cellular base stations or Home Node Bs (HNBs) designed for use in the home or business

environment and are connected to the mobile network

operator's macro network. They are becoming ever more important as they provide improved network coverage

indoors, amongst other advantages.

In order to facilitate handover (HO) of a subscriber

station or mobile device from one femto cell to another, it is required to know the available neighbour cells.

Neighbour cell relationships and neighbour cell lists

(NCLs) ) are generally established by Automatic Neighbor

Relation (ANR) functions using the mobile device or user equipment (UE) . A UE ANR log contains not just an entry for one cell, but rather many entries since the start of logging the ANRs by the UE . Each entry reports neighbour cell relations for all cells which the UE has traversed since it started logging the ANRs. If the UE is attached to a HNB cell, it typically reports only HNB cells neighbouring to the attached HNB-cell.

The UE, under configurable conditions, reads relevant system information broadcasted by cells neighbouring the cell currently serving the UE . The UE then stores the neighbour cell information internally and reports the collected information at a later point in time to a network control node; i.e. a radio network controller

(RNC) or a Home Node B gateway (HNB-GW) , which is not necessarily the one to which it was connected when it starting reading the neighbour cells' system information. This means that neighbour relation information is simply discarded and gets lost, which can lead to missing or outdated entries on an ANR log or neighbour cell list, and therefore to HO failure.

In order to allow a larger (campus or corporate) 3G HNB network to operate without detailed pre-configuration of the respective HNB neighbour relations, the HNB would have the possibility to scan its environment and request Iurh-connectivity towards its neighbour HNB.

However, as an existing lurh connectivity can typically only be assumed between directly neighbouring HNBs and HNBs typically only serve small geographical areas, a successful update of NCLs via ANR log report is of very low probability. Moreover, if the UE reports a missing neighbour relation between 3G HNBs, and a missing

neighbour relation would coincide with a missing Iurh connection, if this connectivity is not pre-configured, the necessity of a respective solution is evident.

A further problem is that a macro cell is not concerned about receiving UE ANR logbook entries containing

information from HNB cells.

The invention seeks to solve at least some of the

aforementioned problems.

SUMMARY OF THE INVENTION

Accordingly, embodiments of the invention provide a method, which includes measuring a neighbour cell at a subscriber station, reporting the measured neighbour cell to a first network node, forwarding a report of the measured neighbour cell from the network node to a control node, and sending the neighbour cell report from the control node to a second network node associated with the neighbour cell included in the measured neighbour cell report.

A neighbour cell is measured at a subscriber station in a communications network. The measured neighbour cell is reported to a first network node, then the first network node forwards the report of the measured neighbour cell node to a control node. The control node then sends the neighbour cell report to a second network node associated with the neighbour cell that was measured by the

subscriber station and included in the measured neighbour cell report.

In this way, an actual measured neighbour cell

relationship is reported to the network and used to update a neighbour cell list, thereby improving neighbour cell relationships by providing correct information about actual available cells. This leads to an improved QoS, as well as more reliable voice calls and data transfer.

The control node can receive and align measured neighbour cell information with its configuration, which results in improved network quality, continued service quality during HO due to actual and up to date neighbour cell information, as well as improved HO behaviour with reduced HO failure due to missing or outdated neighbour cell information.

A further advantage is that efforts, costs and drive tests to verify network deployment are reduced due to simplified and more efficient measurement and reporting of information about neighbour cells. This provides the benefit of adding new cells into the network without prior planning and prior synchronisation with other control nodes. Preferably, the method further includes evaluating the neighbour cell report at the control node and, based on a result of the evaluation, sending the report only to network nodes associated with cells included in the neighbour cell report. This provides the advantage that non-neighbour cells do not receive unnecessary

information .

The neighbour report may also be sent to a network node serving a cell in which the subscriber station is

currently located. This network node may be the same as the first network node.

The method may further include storing measurement information in an Automatic Neighbour Relation log at the subscriber station. A memory in the subscriber station may store the neighbour cell measurement in an Automatic Neighbour Relation log, which contains entries of

neighbour cells.

An instruction may be sent to the first network node to set up an interface with the second network node

associated with the reported neighbour cell. The control node may send an instruction to the first network node to set up an interface (e.g. an Iurh interface) with the second control node so that they may communicate with each other and exchange neighbour cell information.

Alternatively, or in addition, the control node may instruct the first network node that it is allowed to exchange signalling with second network node in the reported neighbour cell.

Preferably, the first network node evaluates the measured neighbour cell report for a new neighbour cell and updates a neighbour cell list with reported parameters from the neighbour cell report.

Furthermore, an Automatic Neighbour Relation log

identifier may be added to the neighbour cell report.

The first control node may add the ANR log identifier to the neighbour cell report before sending it to the control node. Then the network node can also add a list of network nodes through which the Automatic Neighbour Relation log has already passed to the neighbour cell report. In this way, the control node does not have to send unnecessary neighbour relation information to cells that already have this information.

The neighbour cell report may also be sent to a second control node corresponding to the reported measured neighbour cell. The second control node may be

associated with a macro cell (in which case the control node is an RNC) or a femto cell (in which case the control node is an HNB-GW) . The neighbour cell report may either be sent to the second control node via an Iur interface or via a core network. Further embodiments of the invention provide a subscribe station. The subscriber station includes a measurement unit configured to measure a neighbour cell, and a transmitter unit configured to send a report of the measured neighbour cell to a network node.

Preferably, the subscriber station further includes a data storage unit configured to store measurement

information in an Automatic Neighbour Relation log.

Additional embodiments of the invention provide a network node, which includes a receiver unit configured to receive a report of a measured neighbour cell from a subscriber station, and a transmitter unit configured to forward the report of the measured neighbour cell to a control node.

The network node may further include a processor, which is configured to evaluate the measured neighbour cell report for a new neighbour cell and configured to update a neighbour cell list with reported parameters from the neighbour cell report. The processor may be further configured to add an Automatic Neighbour Relation log identifier to the neighbour cell report. In addition, the processor may be configured to add a list of network nodes through which the Automatic Neighbour Relation log has already passed to the neighbour cell report. Further embodiments of the invention provide a control node. The control node includes a receiver unit

configured to receive a report of a measured neighbour cell from a first network node and a transmitter unit configured to send the report to a second network node associated with a neighbour cell included in the measured neighbour cell report.

Preferably, the control node further includes a processor configured to evaluate the neighbour cell report. Based on a result of the evaluation, the transmitter unit is then configured to send the report only to network nodes associated with cells included in the neighbour cell report. In this way, cells that are not neighbour cells do not receive unnecessary information.

The control node reports an actual measured neighbour cell relationship to a communications network, which can be used to update a neighbour cell list, thereby

improving neighbour cell relationships by providing correct information about actual available cells. This leads to an improved QoS, as well as more reliable voice calls and data transfer.

The control node may be a radio network controller (RNC) or a home Node B gateway (HNB-GW) , for example.

Embodiments of the invention further provide a computer program product including a program comprising software code portions being arranged, when run on a processor, to perform: measuring a neighbour cell at a subscriber station; reporting the measured neighbour cell to a first network node; forwarding a report of the measured

neighbour cell from the network node to a control node; and sending the neighbour cell report from the control node to a second network node associated with the

neighbour cell included in the measured neighbour cell report .

Preferably, the computer program product includes a computer-readable medium on which the software code portions are stored, and/or wherein the program is directly loadable into a memory of the processor.

The invention will now be described, by way of example only, with reference to specific embodiments, and to the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a simplified schematic diagram of a

communications network;

Figure 2 is a simplified schematic diagram of a

subscriber station according to an embodiment of the invention ;

Figure 3 is a simplified schematic diagram of a network node according to an embodiment of the invention;

Figure 4 is a simplified schematic diagram of a control node according to an embodiment of the invention; and

Figure 5 is a flow chart illustrating a method according to an embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Figure 1 shows a wireless communications network, which in this example is a UMTS network: however, the following embodiments may be applicable to any wireless

communications network, for example an LTE network.

The network includes two macro cells Ml and M2, which are part of the radio access network (RAN) part of the communications network and are coupled to the core network (CN) part of the communications network.

The macro cell Ml includes femto cells Fl, F2 and F3, which can be accessed via the home Node Bs (HNBs) 1, 2 and 3, respectively. The HNBs 1, 2 and 3 are controlled by a home Node B gateway (HNB-GW) 20, to which they are connected via an Iuh interface. The HNBs 1, 2 and 3 can communicate with each other over an Iurh interface, which may be a direct interface or may be proxied via the HNB-

GW 20. The HNB-GW 20 is coupled to the CN via standard Iu-cs and Iu-ps interfaces.

The macro cell M2 is a neighbour cell to the macro cell Ml and is controlled by a radio network controller (RNC)

4 coupled to the CN over Iu-cs and Iu-ps interfaces. A Node B 5 is controlled by the RNC 4 and provides access to the macro cell M2.

A user equipment (UE) 10 is a subscriber station to the network including the macro cells Ml and M2 and is also in the closed subscriber group (CSG) of the femto network, which includes the cells Fl, F2 and F3.

Handover may take place between the HNBs 1, 2 and 3 via the HNB-HNB Iurh interface, which is able to support all functions defined for RNSAP (as defined in 3GPP TS

25.423) in order to allow RNSAP Relocation between the involved HNBs 1, 2 and 3 without involving the CN at all so that only the HNB-GW 20 is involved. The protocol stack of the lurh interface is basically the same as the Iur interface, except that SCCP is replaced by RNA (a new adaptation layer) over SCTP.

lurh connectivity is either a direct one as illustrated in Figure 1 (lurh signalling traffic is not at all touched by the HNB-GW 20 and each HNB 1, 2, 3 has to have a lurh connection to all its neighbouring HNBs 1, 2, 3) or a HNB-GW routed one (each HNB 1, 2, 3 is lurh

connected to the HNB-GW 20 with a single lurh interface instance and manages all respective lurh signalling via this single lurh interface) . For both connectivity options, means are provided to prevent lurh signalling between HNBs 1, 2, 3 that are not neighbours or do not yet know each other to be neighbours.

In order to allow the setup of lurh connectivity between the respective HNBs 1, 2, 3 affected within the logbook report of the UE 10, a method according to the invention provides that the HNB 1, 2, 3, finally receiving the logbook report of the UE 10, shall communicate the logbook entry towards the HNB-GW (either already

translated into Iurh-connection requests or the logbook entry of the UE10 unchanged) in order to initiate the

HNB-GW 20 providing connectivity information (identity of the HNB 1, 2, 3 and signalling transport addresses for lurh signalling) to the relevant HNBs 1, 2, 3 using the Iuh interface. Figure 2 shows the UE 10 in more detail. In the examples below, the serving cell for the UE 10 is the femto cell Fl . The UE 10 includes a transmit/receive unit 11, and a measurement unit 12, which is configured to measure received signal strength in order to determine a

neighbour cell for HO. A data storage unit 13 is

configured to store the measurement information in an Automatic Neighbour Relation (ANR) log. A processor 14 is included in the UE 10, which can run software to cause the measurement unit 12 to perform the relevant neighbour cell measurements and to cause the transmit/receive unit 11 to forward a report of the neighbour cell measurements to the serving HNB 1, which is shown in more detail in Figure 3: however, all of the HNBs 1, 2 and 3 in the femto network have the same structure and function as each other.

The HNB 1 includes a transmitter 15, a receiver 16 and a processor 17 and is controlled by the HNB-GW 20 over the Iuh interface. The HNB-GW 20 is shown in Figure 4 and also includes a transmitter 21, a receiver 22 and a processor 23.

An embodiment of the invention is illustrated in the flow chart shown in Figure 5. The UE 10 is currently served by the femto cell Fl accessed by the HNB 1 but the transmit/receive unit 11 may also receive signals from other cells in the network (both femto and macro cells) . In step SI, the measurement unit 12 in the UE 10 measures a neighbour cell that could be used for handover, for example F2. The UE 10 may then store the measured neighbour cell F2 in an Automatic Neighbour Relation log contained in its data storage unit 13. The

transmit/receive unit 11 then sends a report of the measured neighbour cell to the HNB 1 in step S2 and the receiver 16 receives the neighbour cell report. (The HNB 1 is just used here as an example - the UE 10 may send a report of the measured neighbour cell to any of the femto cells in the network) . In step S3, the transmitter 15 of the HNB 1 then forwards the report of the measured neighbour to the HNB-GW 20, where it is received by the receiver 22. In step S4 the HNB-GW sends the neighbour cell report to the HNB 2, which is the HNB associated with the neighbour cell F2 included in the measured neighbour cell report.

As another example, if UE 10 stores within the 3G ANR log that it has the potential to handover to HNB2 while being served by HNB1 and reports this to HNB3, the HNB3 may provide this information (e.g. "Source HNB identity = HNB1, HO Candidate = HNB2 ) to the HNB-GW 20, which in turn provides connectivity information to the HNB 1 (and possibly also to the HNB 2), thereby updating the

neighbour relations. The HNB-GW 20 then either causes or instructs the HNB 1 or the HNB 2 to setup a direct Iurh interface or informs them that they are neighbours and that Iurh signalling between them is allowed (if they have already an Iurh connection setup towards the HNB-GW 20, otherwise the HNB 20 causes one or both of the HNBs 1, 2 to setup this Iurh interface to the HNB-GW 20. In one embodiment, the HNB 1, 2 or 3, to which the UE 10 sends the neighbour cell measurement report, evaluates the measured neighbour cell report at the processor 17 to determine whether the report contains a measurement of a new neighbour cell. The processor 17 can then update a neighbour cell list accordingly with reported parameters from the neighbour cell report.

The HNB 1, 2, 3 receiving the neighbour cell measurement report can also add an Automatic Neighbour Relation log identifier and/or a list of HNBs through which the

Automatic Neighbour Relation log has already passed to the neighbour cell report.

In one embodiment, the HNB-GW 20 evaluates the neighbour cell report and then sends the report only to HNBs associated with cells included in the report.

If a different HNB-GW or RNC from the HNB-GW 20 is controlling the HNB associated with the cell (s) included in the neighbour cell report, the HNB-GW 20 also sends the neighbour cell report to that particular control node controlling the measured neighbour cell (s) . For example, the UE 10 may have measured the macro cell M2 as being a neighbour cell. In that case, the HNB-GW 20 will send the neighbour cell report to the RNC 4. The HNB-GW 20 can either send the neighbour cell report to the RNC 4 (or any other relevant control node) via an Iur interface or via the core network. In an alternative embodiment, means are provided to inform the UE 10 whether it shall read system information from cells served by a HNB 1, 2, 3 or if it shall read information from CSG-cells in order to avoid that

respective HNB/CSG-cell related information is reported to macro network nodes. The UE 10 has to be able to read HNB/CSG-cell relevant system information (such as the CSG-Identity and the cell-access-mode) and to report this information to the proper RAN node.

In a further embodiment, the macro-RNC 4 is enabled to forward HNB/CSG relevant information towards the HNB-GW 20 in order to allow for mixed macro/femto deployment where, for example, macro cells serve as an "umbrella layer" for HNB/CSG-networks .

For the purpose of the present invention as described hereinabove, it should be noted that

- method steps likely to be implemented as software code portions and being run using a processor at a network control element or terminal (as examples of devices, apparatuses and/or modules thereof, or as examples of entities including apparatuses and/or modules therefore), are software code independent and can be specified using any known or future developed programming language as long as the functionality defined by the method steps is preserved;

- generally, any method step is suitable to be

implemented as software or by hardware without changing the idea of the embodiments and its modification in terms of the functionality implemented;

- method steps and/or devices, units or means likely to be implemented as hardware components at the above- defined apparatuses, or any module (s) thereof, (e.g., devices carrying out the functions of the apparatuses according to the embodiments as described above) are hardware independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS (Metal Oxide

Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL (Transistor-Transistor Logic), etc., using for example ASIC (Application Specific IC (Integrated

Circuit) ) components, FPGA (Field-programmable Gate

Arrays) components, CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components ;

- devices, units or means (e.g. the above-defined

apparatuses and network devices, or any one of their respective units/means) can be implemented as individual devices, units or means, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device, unit or means is preserved;

- an apparatus may be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of an apparatus or module, instead of being hardware implemented, be

implemented as software in a (software) module such as a computer program or a computer program product comprising executable software code portions for execution/being run on a processor;

- a device may be regarded as an apparatus or as an assembly of more than one apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing, for example.

In general, it is to be noted that respective functional blocks or elements according to above-described aspects can be implemented by any known means, either in hardware and/or software, respectively, if it is only adapted to perform the described functions of the respective parts. The mentioned method steps can be realized in individual functional blocks or by individual devices, or one or more of the method steps can be realized in a single functional block or by a single device.

Generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the present invention. Devices and means can be

implemented as individual devices, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the

functionality of the device is preserved. Such and similar principles are to be considered as known to a skilled person.

The terms "user equipment (UE) " and "mobile station" described herein may refer to any mobile or stationary device including a mobile telephone, a computer, a mobile broadband adapter, a USB stick for enabling a device to access to a mobile network, etc. The exemplary embodiments of the invention have been described above with reference to a 3GPP UMTS network. However, the above-described examples may be applied to any wireless communications network.

Although the invention has been described hereinabove with reference to specific embodiments, it is not limited to these embodiments and no doubt further alternatives will occur to the skilled person, which lie within the scope of the invention as claimed.

LIST OF ABBREVIATIONS

ANR Automatic Neighbour Relation

CSG Closed Subscriber Group

E-UTRAN Enhanced UTRAN

HNB Home Node B

HNB-GW HNB Gateway

NCL Neighbour Cell List

RNC Radio Network Controller

RNSAP Radio Network Subsystem Application Part

SON Self Optimising Networks

UE User Equipment

UTRAN UMTS Terrestrial Radio Access Network

3GPP 3^rd Generation Partnership Project

Claims

1. A method, comprising measuring a neighbour cell at a subscriber station, reporting the measured neighbour cell to a first network node, forwarding a report of the measured neighbour cell from the first network node to a control node, and sending the neighbour cell report from the control node to a second network node associated with the neighbour cell included in the measured neighbour cell report.

2. The method according to claim 1, further comprising evaluating the report at the control node and, based on a result of the evaluation, sending the report only to network nodes associated with cells included in the neighbour cell report.

3. The method according to claim 1 or claim 2, further comprising sending the report to a network node serving a cell in which the subscriber station is currently

located .

4. The method according to any of claims 1 to 3, further comprising storing measurement information in an

Automatic Neighbour Relation log at the subscriber station .

5. The method according to any of claims 1 to 4, further comprising sending an instruction to the first network node to set up an interface with the second network node associated with the reported neighbour cell.

6. The method according to any of claims 1 to 5, further comprising informing the first network node it is allowed to exchange signalling with second network node in the reported neighbour cell.

7. The method according to any of claims 1 to 6, wherein the first network node evaluates the measured neighbour cell report for a new neighbour cell and updates its neighbour cell list with reported parameters from the neighbour cell report.

8. The method according to any of claims 1 to 7, further comprising adding an Automatic Neighbour Relation log identifier to the neighbour cell report.

9. The method according to claim 8, further comprising adding a list of network nodes through which the

10. The method according to any of claims 1 to 9, further comprising sending the neighbour cell report to a second control node corresponding to the reported

measured neighbour cell.

11. The method according to claim 10, wherein the neighbour cell report is sent to the second control node via an Iur interface.

12. The method according to claim 10, wherein the neighbour cell report is sent to the second control node via a core network.

13. A subscriber station, comprising a measurement unit configured to measure a neighbour cell, and a transmitter unit configured to send a report of the measured

neighbour cell to a network node.

14. The subscriber station according to claim 13, further comprising a data storage unit configured to store measurement information in an Automatic Neighbour Relation log.

15. A network node, comprising a receiver unit

configured to receive a report of a measured neighbour cell from a subscriber station, and a transmitter unit configured to forward the report of the measured

neighbour cell to a control node.

16. The network node according to claim 15, further comprising a processor configured to evaluate the

measured neighbour cell report for a new neighbour cell and configured to update a neighbour cell list with reported parameters from the neighbour cell report.

17. The network node according to claim 16, wherein the processor is further configured to add an Automatic

Neighbour Relation log identifier to the neighbour cell report .

18. The network node according to claim 17, wherein the processor is further configured to add a list of network nodes through which the Automatic Neighbour Relation log has already passed to the neighbour cell report.

19. A control node, comprising a receiver unit

20. The control node according to claim 19, further comprising a processor configured to evaluate the report, wherein the transmitter unit is configured to send the report only to network nodes associated with cells included in the neighbour cell report.

21. A computer program product including a program comprising software code portions being arranged, when run on a processor, to perform: measuring a neighbour cell at a subscriber station; reporting the measured neighbour cell to a first network node; forwarding a report of the measured neighbour cell from the network node to a control node; and sending the neighbour cell report from the control node to a second network node associated with the neighbour cell included in the measured neighbour cell report.

22. The computer program product according to claim 21, wherein the computer program product

comprises a computer-readable medium on which the software code portions are stored, and/or wherein the program is directly loadable into a memory of the processor .