WO2014161198A1

WO2014161198A1 - Method and apparatus for managing cell clustering and de-clustering

Info

Publication number: WO2014161198A1
Application number: PCT/CN2013/073756
Authority: WO
Inventors: Wei Hong; Haiming Wang; Chunyan Gao; Jing HAN; Lili Zhang
Original assignee: Broadcom Corporation
Priority date: 2013-04-03
Filing date: 2013-04-03
Publication date: 2014-10-09

Abstract

A method, apparatus, and computer program product are provided to manage cell clustering and de-clustering. In the context of a method, a macro access point (AP) may initially communicate with two or more pico APs in a cell cluster. The macro AP may further determine and transmit one or more de-clustering parameters to the one or more pico APs in the cell cluster. The macro AP may then communicate with the two or more pico APs after they have joined new cell clusters. In the context of another method, a pico AP may receive at least one clustering parameter and at least one de-clustering parameter. The pico AP may further join a first cell cluster based at least in part on the at least one clustering parameter and determine, based at least in part on the at least one de-clustering parameter, whether to join another cluster. The pico AP may further join a second cell cluster based at least in part on the at least one clustering parameter.

Description

METHOD AND APPARATUS FOR MANAGING CELL CLUSTERING AND DE- CLUSTERING

TECHNOLOGICAL FIELD

[0001] An example embodiment of the present invention relates generally to wireless networks and, more particularly, to managing cell clustering and de-clustering within a wireless network.

BACKGROUND

[0002] One of the benefits of time division duplexed wireless communication systems is that they allow for asymmetric uplink/downlink (UL/DL) resource allocation. In the context of a Long Term Evolution (LTE) system, such asymmetric resource allocation may be implemented by providing multiple semi-statically configured uplink-downlink configurations. These allocations may provide between 40% and 90% DL subframes. Currently-deployed LTE systems assume that the same TDD configurations are being used in each cell because, otherwise, interference between UL and DL, including both enhanced Node B (eNB)-to-eNB and user equipment (UE)-to-UE interference, would need to be considered. In local area (LA) networks, however, due to small number of active UEs per cell, the traffic situation may fluctuate frequently, and TDD reconfiguration to adapt to the traffic may provide improved resource efficiency and power saving.

[0003] One scheme for mitigating interference when using flexible TDD configurations is Cell Clustering Interference Mitigation (CCIM) (referred to herein simply as "cell clustering"). Cell clustering involves, unsurprisingly, creating "clusters" of one or more cells. Within each cell cluster, the active transmissions of all cells in the cluster are either uplink or downlink in any subframe or a subset of all subframes. In this way, eNB-to-eNB interference and UE-to-UE interference is mitigated within each cell cluster. For cell clustering to be successfully deployed, coordination between the multiple cells belonging to the same cell cluster is needed, as are mechanisms for managing cell clustering de-clustering. BRIEF SUMMARY

[0004] A method, apparatus and computer program product are therefore provided according to an example embodiment in order to manage cell clustering and de-clustering in a wireless network. In this regard, the method, apparatus, and computer program product of an example embodiment may provide for the transmission of at least one de-clustering parameter to pico cells in a first cluster, so as to allow de-clustering decisions to be made based thereon. The de- clustering parameter may, for example, comprise a cluster-size threshold, a cluster traffic load threshold, a coordination latency threshold, an inter-cluster interference level threshold, or other parameters.

[0005] In one embodiment, a method is provided that includes communicating with at least a first and second pico access point included in a first cell cluster, determining at least one de- clustering parameter, and causing the at least one de-clustering parameter to be transmitted to at least one of the first or second pico access points included in the first cell cluster. The method further includes communicating, subsequent to causing the at least one de-clustering parameter to be transmitted, with at least the first and second pico access points, the first pico access point being included in a second cell cluster and the second pico access point being included in a third cell cluster.

[0006] In another embodiment, a method is provided that includes receiving at least one clustering parameter and at least one de-clustering parameter and joining, based at least in part on the at least one clustering parameter, a first cell cluster. The method further includes determining whether to join another cluster, based at least in part on the at least one de-clustering parameter and, in an instant in which it is determined to join another cluster, joining a second cluster based at least in part on the at least one clustering parameter.

[0007] In a further embodiment, an apparatus is provided that includes at least one processor and at least one memory storing program code instructions therein, the memory and program code instructions being configured to, with the processor, cause the apparatus to at least communicate with at least a first and second pico access point included in a first cell cluster, determine at least one de-clustering parameter, and cause the at least one de-clustering parameter to be transmitted to at least one of the first or second pico access points included in the first cell cluster. The apparatus is further directed to communicate, subsequent to causing the at least one de-clustering parameter to be transmitted, with at least the first and second pico access points, the first pico access point being included in a second cell cluster and the second pico access point being included in a third cell cluster.

[0008] In another embodiment, an apparatus is provided that includes at least one processor and at least one memory storing program code instructions therein, the memory and program code instructions being configured to, with the processor, cause the apparatus to at least receive at least one clustering parameter and at least one de-clustering parameter and join, based at least in part on the at least one clustering parameter, a first cell cluster. The apparatus is further directed to determine whether to join another cluster, based at least in part on the at least one de- clustering parameter and, in an instant in which it is determined to join another cluster, join a second cluster based at least in part on the at least one clustering parameter.

[0009] In a further embodiment, a computer program product is provided that includes a non- transitory computer readable medium storing computer program code portions therein, the computer program code portions being configured to, upon execution, cause an apparatus to at least communicate with at least a first and second pico access point included in a first cell cluster, determine at least one de-clustering parameter, and cause the at least one de-clustering parameter to be transmitted to at least one of the first or second pico access points included in the first cell cluster. The apparatus is further directed to communicate, subsequent to causing the at least one de-clustering parameter to be transmitted, with at least the first and second pico access points, the first pico access point being included in a second cell cluster and the second pico access point being included in a third cell cluster.

[0010] In another embodiment, a computer program product is provided that includes a non- transitory computer readable medium storing computer program code portions therein, the computer program code portions being configured to, upon execution, cause an apparatus to at least receive at least one clustering parameter and at least one de-clustering parameter and join, based at least in part on the at least one clustering parameter, a first cell cluster. The apparatus is further directed to determine whether to join another cluster, based at least in part on the at least one de-clustering parameter and, in an instant in which it is determined to join another cluster, join a second cluster based at least in part on the at least one clustering parameter.

[0011] In yet another embodiment, an apparatus is provided that includes means for communicating with at least a first and second pico access point included in a first cell cluster, means for determining at least one de-clustering parameter, and means for causing the at least one de-clustering parameter to be transmitted to at least one of the first or second pico access points included in the first cell cluster. The apparatus further includes means for communicating, subsequent to causing the at least one de-clustering parameter to be transmitted, with at least the first and second pico access points, the first pico access point being included in a second cell cluster and the second pico access point being included in a third cell cluster.

[0012] In an even further embodiment, an apparatus is provided that includes means for receiving at least one clustering parameter and at least one de-clustering parameter and means for joining, based at least in part on the at least one clustering parameter, a first cell cluster. The apparatus further includes means for determining whether to join another cluster, based at least in part on the at least one de-clustering parameter and means for joining, in an instant in which it is determined to join another cluster, a second cluster based at least in part on the at least one clustering parameter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Having thus described certain example embodiments of the present disclosure in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

[0014] Figures 1 and 2 are illustrations of systems which may benefit from embodiments of the present invention;

[0015] Figure 3 is a block diagram of an apparatus that may be configured in accordance with an example embodiment of the present invention;

[0016] Figure 4 is a flowchart depicting the operations performed by an apparatus embodied by or otherwise associated with a macro access point (MAP); and

[0017] Figure 5 is a flowchart depicting the operations performed by an apparatus embodied by or otherwise associated with a local area access point (LAAP).

DETAILED DESCRIPTION

[0018] The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0019] As used in this application, the term "circuitry" refers to all of the following:

(a)hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) to combinations of circuits and software (and/or firmware), such as (as applicable): (i) to a combination of processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that

require software or firmware for operation, even if the software or firmware is not

physically present.

[0020] This definition of "circuitry" applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or application specific integrated circuit for a mobile phone or a similar integrated circuit in server, a cellular network device, or other network device.

[0021] Referring now to Figure 1, a system supporting cell clustering is depicted. As depicted, a macro access point (AP) 100 may serve a macro cell 101 and a plurality of local area APs 110, alternatively referred to as a pico APs, may serve one or more local area cells (not depicted), also known as picocells. The coverage area of a macro cell 101 may be larger than that of a given picocell, and may even overlap with or encompass one or more picocells. As shown in Figure 1, one or more pico APs 110 may form one or more clusters, such as clusters 1, 2, 3, or 4 as depicted. As discussed in the background, UL and DL transmissions may be coordinated within a given cluster such that active transmissions of all picocells within the same cluster are either uplink or downlink in any subframe or a subset of all subframes. In this way, eNB-to-eNB interference and UE-to-UE interference may be mitigated within each cell cluster.

[0022] Turning now to Figure 2, one example of the concept of de-clustering is depicted, along with one example of a circumstance in which de-clustering may be desirable. In the depicted example, de-clustering has been triggered in response to there being too many pico cells in a given cluster. That is, beginning from the system state depicted in Figure 1 , if pico APs 5 and 6 were to join cluster #1 it may be desirable to de-cluster cluster #1 and have pico APs 1, 2, 6, and 5 join a first cluster (e.g., new cluster #1) and pico APs 3, 4, and 7 join a second cluster (e.g., new cluster #5). Further examples of conditions for performing such de-clustering will be discussed in detail below.

[0023] The systems depicted in Figures 1 and 2 may support communications between a user equipment and a network, such as a Universal Mobile Telecommunications System (UMTS) network, a Long Term Evolution (LTE) network, an LTE- Advanced (LTE-A) network, a Global Systems for Mobile communications (GSM) network, a Code Division Multiple Access (CDMA) network, e.g., a Wideband CDMA (WCDMA) network, a CDMA2000 network or the like, a Frequency -Division Multiplexing (FDM) network, e.g., an Orthogonal Frequency-Division Multiplexing (OFDM) network, a General Packet Radio Service (GPRS) network or other type of network, via one or more access points, such as the macro AP 100 and/or the pico APs 110.

[0024] It will be understood that, as used herein, an AP, such as macro AP 100 or pico AP 110, may refer to any communication device which provides connectivity to a network. For example, an AP may refer to a base station, an access node, or any equivalent, such as a Node B, an evolved Node B (eNB), a relay node, or other type of access point. The term "user

equipment" (UE) includes any mobile communication device such as, for example, a mobile telephone, portable digital assistant (PDA), pager, laptop computer, a tablet computer, or any of numerous other hand held or portable communication devices, computation devices, content generation devices, content consumption devices, data card, Universal Serial Bus (USB) dongle, or combinations thereof. The communications between the UE and any of the APs discussed herein may include the transmission of data via an uplink and/or downlink that is granted between the user equipment and the AP.

[0025] The macro and/or pico APs 100, 110, as well as any UEs, may embody or otherwise be associated with an apparatus 20 that is generally depicted in Figure 3 and that may be configured in accordance with an example embodiment of the present invention as described below. However, it should be noted that the components, devices or elements described below may not be mandatory and thus some may be omitted in certain embodiments. Additionally, some embodiments may include further or different components, devices or elements beyond those shown and described herein. [0026] As shown in Figure 3, however, the apparatus 20 may include or otherwise be in communication with a processing system including processing circuitry, such as the processor 20 and, in some embodiments, the memory 24, which is configurable to perform actions in accordance with example embodiments described herein. The processing circuitry may be configured to perform data processing, application execution and/or other processing and management services according to an example embodiment of the present invention. In some embodiments, the apparatus or the processing circuitry may be embodied as a chip or chip set. In other words, the apparatus or the processing circuitry may comprise one or more physical packages (e.g., chips) including materials, components and/or wires on a structural assembly (e.g., a baseboard). The structural assembly may provide physical strength, conservation of size, and/or limitation of electrical interaction for component circuitry included thereon. The apparatus or the processing circuitry may therefore, in some cases, be configured to implement an embodiment of the present invention on a single chip or as a single "system on a chip." As such, in some cases, a chip or chipset may constitute means for performing one or more operations for providing the functionalities described herein.

[0027] In an example embodiment, the processing circuitry may include a processor 22 and memory 24 that may be in communication with or otherwise control a communication interface 26. As such, the processing circuitry may be embodied as a circuit chip (e.g., an integrated circuit chip) configured (e.g., with hardware, software or a combination of hardware and software) to perform operations described herein. However, in some embodiments taken in the context of an AP 100, 110 or a UE, the processing circuitry may be embodied as a portion of the AP or UE.

[0028] The communication interface 26 may include one or more interface mechanisms for enabling communication with other devices and/or networks. In some cases, the communication interface may be any means such as a device or circuitry embodied in either hardware, or a combination of hardware and software that is configured to receive and/or transmit data from/to a network and/or any other device or module in communication with the processing circuitry, such as between the UE and an AP 100, 110. In this regard, the communication interface may include, for example, an antenna (or multiple antennas) and supporting hardware and/or software for enabling communications with a wireless communication network and/or a communication modem or other hardware/software for supporting communication via cable, digital subscriber line (DSL), universal serial bus (USB), Ethernet or other methods.

[0029] In an example embodiment, the memory 24 may include one or more non-transitory memory devices such as, for example, volatile and/or non- volatile memory that may be either fixed or removable. The memory may be configured to store information, data, applications, instructions or the like for enabling the apparatus 20 to carry out various functions in accordance with example embodiments of the present invention. For example, the memory could be configured to buffer input data for processing by the processor 22. Additionally or alternatively, the memory could be configured to store instructions, e.g., program code portions, for execution by the processor. As yet another alternative, the memory may include one of a plurality of databases that may store a variety of files, contents or data sets. Among the contents of the memory, applications may be stored for execution by the processor in order to carry out the functionality associated with each respective application. In some cases, the memory may be in communication with the processor via a bus for passing information among components of the apparatus.

[0030] The processor 22 may be embodied in a number of different ways. For example, the processor may be embodied as various processing means such as one or more of a

microprocessor or other processing element, a coprocessor, a controller or various other computing or processing devices including integrated circuits such as, for example, an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), or the like. In an example embodiment, the processor may be configured to execute instructions stored in the memory 24 or otherwise accessible to the processor. As such, whether configured by hardware or by a combination of hardware and software, the processor may represent an entity (e.g., physically embodied in circuitry - in the form of processing circuitry) capable of performing operations according to embodiments of the present invention while configured accordingly.

Thus, for example, when the processor is embodied as an ASIC, FPGA or the like, the processor may be specifically configured hardware for conducting the operations described herein.

Alternatively, as another example, when the processor is embodied as an executor of software instructions, the instructions may specifically configure the processor to perform the operations described herein. [0031] As noted in the Background section, cell clustering may be useful for decreasing UL and DL AP-to-AP and UE-to-UE interference in wireless networks. In systems utilizing cell clustering, the need to split, or "de-cluster," cells may arise. For example, interference may increase as the number of pico cells incorporated into any given cluster grows, thus leading to a need to de-cluster the increasingly large cluster, such as into two or more smaller clusters. Two methods for de-clustering have been proposed thus far. The first is to relax one or more clustering parameters, such as a coupling loss parameter, interference level parameter, or the like. For example, a coupling loss threshold of 70dB may be used instead of 90dB. Relaxing a clustering parameter in this way may thus decrease cluster sizes and, accordingly, increase the number of clusters. The second proposed method is to select a "cutting cell" to remove from the cluster, and then to decrease the DL-UL interference from the cutting cell to other cells in the cluster.

[0032] Regardless of what de-clustering method is chosen, whether one of the two options discussed above or any other option, some issues arise. First, they do not resolve the issue of when to de-cluster, either by relaxing one or more clustering parameters, selecting a cutting cell, or by some other method. A further issue, which may especially apply when de-clustering by the first method, i.e., clustering parameter relaxation, is that de-clustering may require additional signaling. For instance, the most straightforward way to relax a clustering parameter may be for a macro AP to reconfigure the clustering parameter via X2 signaling. However, this may cause an increased signaling burden on the X2 interface if the number of pico cells is large. With respect to the cutting cell method, it may be difficult to find a cutting cell with which to perform the de-clustering.

[0033] Accordingly, various methods, apparatuses, and computer program products for managing cell clustering and de-clustering are described herein. According to one example embodiment, pico cells may be provided with one or more de-clustering parameters and, according to a further embodiment, one or more clustering parameters. According to yet another example embodiment, the clustering and de-clustering parameters may be implicitly mapped, thereby reducing signaling burden.

[0034] Thus, having described general concepts of the present invention, reference will now be made to Figures 4 and 5 so as to discuss example embodiments of the present invention in further detail. In this regard, the flowchart contained in Figure 4, along with its accompanying discussion, pertains to operations performed by an apparatus, such as the apparatus 20 depicted in Figure 3, embodied by or otherwise associated with a macro AP, such as the MAP 100 depicted in Figure 1 and 2. Figure 5, along with its accompanying discussion, pertains to particular operations performed by an apparatus, such as the apparatus 20 depicted in Figure 3, embodied by or otherwise associated with a pico AP, such as one or more of the pico APs 110 depicted in Figures 1 and 2.

[0035] Turning first to Figure 4, an apparatus 20 embodied by or otherwise associated with a macro AP, such as macro AP 100, may include means, such as the processing circuitry, the processor 22, the communications interface 26 or the like, for communicating with at least a first and second pico AP included in a first cell cluster. See operation 400. That is, the apparatus 20 embodied by or otherwise associated with the macro AP may send and/or receive one or more signals from two or more pico access points serving two or more respective pico cells that are included in the same cell cluster. The cell cluster may, for example, have been previously formed according to any clustering scheme, such as based on one or more clustering parameters, such as a coupling loss parameter, such as a coupling loss threshold; an interference level parameter, such as an interference level threshold; or the like.

[0036] The apparatus 20 may further include means, such as those just described, for determining at least one de-clustering parameter. See operation 410. According to one example embodiment, the at least one de-clustering parameter may comprise a cluster-size threshold, e.g., a number of pico cells or pico access points in a cluster, above which de-clustering may be triggered. According to another example embodiment, the at least one de-clustering parameter may comprise a cluster traffic load threshold, e.g., a traffic load of pico cells within a cluster, above which de-clustering may be triggered. The cluster traffic load may, for example, comprise a difference in a DL and/or UL ratio of one or more pico cells within a cluster. Determining the cluster traffic load may, according to some example embodiments, involve some degree of coordination between pico cells within the cluster. According to another example embodiment, the at least one de-clustering parameter may comprise an inter-cluster interference level threshold, e.g., an inter-cluster interference level above which de-clustering may be triggered. According to yet another example embodiment, the at least one clustering parameter may comprise a coordination latency threshold, e.g., a coordination latency measurement above which de-clustering may be triggered. Any number of other de-clustering parameters may also be used according to example embodiments, such as any measurement or characteristic of a cell cluster or the cells within a cell cluster which may tend to indicate that de-clustering would improve system performance.

[0037] It will be understood that the at least one de-clustering parameter may comprise a combination of two or more de-clustering parameters. According to a further example embodiment, the two or more de-clustering parameters may be weighted or prioritized with respect to one another. According to a further example embodiment, de-clustering may be triggered by a logical operation performed on the two or more de-clustering parameters. For example, according to an embodiment in which a cluster-size threshold and a cluster traffic load threshold are both used, de-clustering may be triggered only if both thresholds are exceeded.

According to another example embodiment, exceeding only one of the thresholds may trigger de- clustering. It will be further understood that although thresholds may be described herein as being "exceeded," such thresholds and their associated parameters may just as easily be configured to work in reverse, such that de-clustering is triggered unless a threshold is met. Accordingly, references to a threshold being exceeded will be understood not to be directionally limited.

[0038] The apparatus 20 embodied by or otherwise associated with a macro AP, such as macro AP 100, may further include means, such as the processing circuitry, the processor 22, the communications interface 26 or the like, for causing the at least one de-clustering parameter to be transmitted to at least one of the first or second pico cells included in the first cell cluster. See operation 420. The at least one de-clustering parameter may, for example, comprise one or more of the example de-clustering parameters discussed above. The apparatus 20 may further include means, such as those just mentioned, for causing at least one clustering parameter to be communicated to at least one of the first or second pico cells. See operation 430. The at least one clustering parameter may, for example, comprise one or more of a coupling loss parameter, an interference level parameter, or the like. According to an example embodiment, the at least one clustering parameter may be mapped, e.g., implicitly mapped, to the at least one de-clustering parameter. In this way, a pico AP may, for example, be able to determine one parameter from the other based at least in part on the mapping therebetween, such that only one of the parameters may need to be explicitly signaled, e.g., transmitted, to the pico AP. According to an example embodiment, the at least one de-clustering parameter and/or at least one clustering parameter, whether mapped to one another or not, may be included in an X2 SETUP RESPONSE message.

[0039] At this point, after at least one of the first or second pico cells has received the de- clustering parameter, the first cell cluster (which includes the first and second pico cells) may de- cluster and join new clusters based at least in part on the de-clustering parameter and/or the clustering parameter. After de-clustering or after joining the new clusters, one or more of the pico cells may transmit an indication of a cluster change event, as will be discussed later. Thus, the apparatus 20 embodied by or otherwise associated with a macro AP, such as macro AP 100, may further include means, such as the processing circuitry, the processor 22, the

communications interface 26 or the like, for receiving the indication of the cluster change event. See operation 440. According to an example embodiment, the indication of the cluster change event may include a cluster size and/or a cluster ID. The cluster ID may, for example, be assigned by the macro AP or, according to another example embodiment, using one Global eNB ID of one pico AP within the cluster to avoid collision. The indication of the cluster change may, according to an example embodiment, comprise an ENB CONFIGURATION UPDATE message.

[0040] The apparatus 20 embodied by or otherwise associated with a macro AP, such as macro AP 100, may further include means, such as those discussed above, for communicating with at least the first and second pico APs, the first pico AP being included in a second cell cluster and the second pico AP being included in a third cell cluster. See operation 450. It will be understood that the second or third cell cluster may not, in fact, be different (such as in the sense that it has a different cluster ID) from the first cell cluster. That is, although the two pico APs were previously described as being included in a first cell cluster and are now described as being included in second and third cell clusters, this would also encompass a scenario whereby one of the pico APs appears to simply exits the first cluster while the other remains in the first cluster. It will be further understood that a cell cluster may, in some cases, include only a single pico AP.

[0041] The apparatus 20 embodied by or otherwise associated with a macro AP, such as macro AP 100, may further include means, such as the processing circuitry, the processor 22, the communications interface 26 or the like, for reconfiguring the at least one de-clustering parameter and causing the reconfigured at least one de-clustering parameter to be transmitted, such as to one or more of the pico APs. See operations 460 and 470. That is, the macro AP may, on occasion, determine one or more new de-clustering parameters and communicate these new de-clustering parameters to one or more of the pico APs. According to another example embodiment, the apparatus embodied by or otherwise associated with the macro AP may additionally or alternatively include means for reconfiguring and transmitting one or more clustering parameters.

[0042] Turning now to Figure 5 an apparatus 20 embodied by or otherwise associated with a pico AP, such as one or the pico APs 110 of Figures 1 and 2, may include means, such as the processing circuitry, the processor 22, the communications interface 26 or the like, for receiving at least one clustering parameter. See operation 500. As discussed above, the at least one clustering parameter may, for example, comprise one or more of a coupling loss parameter, an interference level parameter, or the like. The apparatus 20 may further include means, such as those just listed, for receiving at least one de-clustering parameter. As discussed above, the at least one de-clustering parameter may, for example, comprise one or more of a cluster-size threshold, a cluster traffic load threshold, an inter-cluster interference level threshold, a coordination latency threshold, or any other measurement or characteristic of a cell cluster or the cells or APs within a cell cluster which may tend to indicate that de-clustering would improve system performance. As discussed above, the at least one clustering parameter and the at least one de-clustering parameter may be mapped, e.g., implicitly mapped, to one another. In this way, a pico AP may, for example, be able to determine at least one clustering parameter based on at least one de-clustering parameter. As discussed above, the at least one de-clustering parameter and/or the at least one clustering parameter may, according to an example embodiment, be included in an X2 SETUP RESPONSE message.

[0043] The apparatus 20 embodied by or otherwise associated with a pico AP may further include means, such as those discussed above, for joining a first cell cluster based at least in part on the at least one clustering parameter. See operation 520. The apparatus 20 may further include means, such as those discussed above, for determining, based at least in part on the at least one de-clustering parameter, whether to join another cluster. See operation 530. That is, the apparatus 20 may include means for determining, based at least in part on the de-clustering parameter, whether to de-cluster. The apparatus 20 may further include means for determining at least one new clustering parameter based at least in part on the at least one de-clustering parameter.

According to an example embodiment, this determination may be further based on a mapping between the at least one clustering parameter and the at least one de-clustering parameter. The apparatus 20 may further include means, such as those discussed above, for joining a second cell cluster based at least in part on the at least one clustering parameter. See operation 550.

[0044] Thus, to summarize operations 530 through 550, the apparatus 20 may, according to an example embodiment, determine that at least one de-clustering parameter, such as at least one of the thresholds discussed above, has been satisfied such that de-clustering should occur. The apparatus 20 may then, upon making such a determination, determine at least one clustering parameter, such as based on a mapping between the de-clustering parameter and the at least one new clustering parameter. As discussed above, the new clustering parameter may, for example, comprise a relaxed coupling loss threshold or the like which, when adopted by the one or more pico APs, may cause cluster sizes to decrease, thus causing one or more existing clusters to be de-clustered, i.e., broken apart, and causing the one or more pico APs to join new and, in some cases, smaller, clusters.

[0045] The apparatus 20 embodied by or otherwise associated with a pico AP may further include means, such as the processing circuitry, the processor 22, the communications interface 26 or the like, for causing an indication of a cluster event change to be transmitted. See operation 560. The indication may, for example, be caused to be transmitted after the pico AP de-clusters, e.g., leaves its original cluster, or following clustering, e.g., after the pico AP joins a new cluster. As discussed above, the indication of the cluster change event may, for example, include one or more of a cluster ID and/or a cluster size, such as a cluster ID and/or size of the new cluster joined by the pico AP. As discussed above, the cluster ID may, for example, be assigned by the macro AP or, according to another example embodiment, using one Global eNB ID of one pico AP within the cluster to avoid collision. Also as discussed above, the indication of the cluster change event may, for example, be included in an ENB CONFIGURATION UPDATE message. The apparatus 20 may further include means, such as those listed above, for receiving at least on reconfigured de-clustering parameter. See operation 570. As illustrated, upon receiving the reconfigured de-clustering parameter the apparatus 20 embodied by or otherwise associated with the pico AP may repeat operations 530-560, discussed above.

[0046] Having thus described the various operations which may be performed by apparatuses respectively embodied by or otherwise associated with a macro AP and a pico AP and configured to manage cell clustering and de-clustering, examples of two of the above-discussed signals which may be used during such clustering and de-clustering will now be provided. [0047] In this regard, a summary of the structure and characteristics of an X2 SETUP RESPONSE message according to an example embodiment is provided below. Rows which represent additions to a conventional X2 SETUP RESPONSE message are indicated with a leading asterisk (*):

[0048]

A summary of the structure and characteristics of an ENB CONFIGURATION message according to an example embodiment is provided below. Rows which represent additions to a conventional ENB CONFIGURATION UPDATE message are again indicated with a leading asterisk (*):

[0050]

[0051] As discussed above, figures 4 and 5 are flowcharts illustrating operations performed by a method, apparatus and computer program product, such as apparatus 20 of Figure 3 in accordance with example embodiments of the present invention. It will be understood that each block of the flowchart, and combinations of blocks in the flowchart, may be implemented by various means, such as hardware, firmware, processor, circuitry and/or other device associated with execution of software including one or more computer program instructions. For example, one or more of the procedures described herein may be embodied by program code instructions, e.g., program code portions. In this regard, the program code instructions which embody the procedures described above may be stored by a memory 24 of an apparatus employing an embodiment of the present invention and executed by a processor 22 in the apparatus. As will be appreciated, any such program code instructions may be loaded onto a computer or other programmable apparatus (e.g., hardware) to produce a machine, such that the resulting computer or other programmable apparatus provides for implementation of the functions specified in the flowchart blocks. These program code instructions may also be stored in a non-transitory computer-readable storage memory that may direct a computer or other programmable apparatus to function in a particular manner, such that the instructions stored in the computer-readable storage memory produce an article of manufacture, the execution of which implements the function specified in the flowchart blocks. The program code instructions may also be loaded onto a computer or other programmable apparatus to cause a series of operations to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide operations for implementing the functions specified in the flowchart blocks. As such, the operations of Figures 4 and 5, when executed, convert a computer or processing circuitry into a particular machine configured to perform an example embodiment of the present invention.

Accordingly, the operations of Figures 4 and 5 define an algorithm for configuring a computer or processing circuitry, e.g., processor, to perform an example embodiment. In some cases, a general purpose computer may be provided with an instance of the processor which performs the algorithms of Figures 4 and 5 to transform the general purpose computer into a particular machine configured to perform an example embodiment.

[0052] Accordingly, blocks of the flowcharts support combinations of means for performing the specified functions and combinations of operations for performing the specified functions. It will also be understood that one or more blocks of the flowchart, and combinations of blocks in the flowchart, can be implemented by special purpose hardware-based computer systems which perform the specified functions, or combinations of special purpose hardware and computer instructions.

[0053] In some embodiments, certain ones of the operations above may be modified or further amplified as described below. Moreover, in some embodiments additional optional operations may also be included. It should be appreciated that each of the modifications, optional additions or amplifications below may be included with the operations above either alone or in combination with any others among the features described herein. [0054] Example embodiments of the present invention may provide many benefits over the prior art. For example, certain example embodiments described above may allow for well- defined yet flexible de-clustering conditions, thereby increasing network performance. Certain example embodiments may further reduce signaling, e.g., X2 signaling, by using implicit mapping between de-clustering and clustering parameters.

[0055] Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

WHAT IS CLAIMED:

1. A method comprising:

communicating with at least a first and second pico access point included in a first cell cluster;

determining at least one de-clustering parameter;

causing the at least one de-clustering parameter to be transmitted to at least one of the first or second pico access points included in the first cell cluster; and

communicating, subsequent to causing the at least one de-clustering parameter to be transmitted, with at least the first and second pico access points, the first pico access point being included in a second cell cluster and the second pico access point being included in a third cell cluster.

2. The method of claim 1, wherein the de-clustering parameter comprises a cluster- size threshold.

3. The method of either of claims 1 or 2, wherein the de-clustering parameter comprises a cluster traffic load threshold.

4. The method of any of claims 1 to 3, wherein the de-clustering parameter comprises an inter-cluster interference level threshold.

5. The method of any of claims 1 to 4, wherein the de-clustering parameter comprises a coordination latency threshold.

6. The method of any of claims 1 to 5, further comprising:

reconfiguring the at least one de-clustering parameter, and

causing the reconfigured at least one de-clustering parameter to be transmitted.

7. The method of any of claims 1 to 6, further comprising receiving an indication of a cluster change event.

8. The method of claim 7, wherein the indication of the cluster change event comprises at least one of an indication of a cluster ID or an indication of a cluster size.

9. The method of claim 8, further comprising assigning the cluster ID.

10. The method of claim 8, wherein the cluster ID is assigned using at least one Global eNB ID of a pico AP within.

11. The method of either of claims 7 or 8, wherein the indication of the cluster change event comprises an ENB CONFIGURATION UPDATE message.

12. The method of any of claims 1 to 11, further comprising causing a clustering parameter to be communicated to at least one of the first or second pico access points.

13. The method of claim 12, wherein the clustering parameter is mapped to the at least one de-clustering parameter.

14. The method of either of claims 12 or 13, wherein the clustering parameter comprises a coupling loss threshold.

15. A method comprising:

receiving at least one clustering parameter and at least one de-clustering parameter; joining, based at least in part on the at least one clustering parameter, a first cell cluster; determining, based at least in part on the at least one de-clustering parameter, whether to join another cluster; and

joining, based at least in part on the at least one clustering parameter, a second cluster in an instant in which it is determined to join another cluster.

16. The method of claim 15, wherein the de-clustering parameter comprises a cluster-size threshold.

17. The method of either of claims 15 or 16, wherein the de-clustering parameter comprises a cluster traffic load threshold.

18. The method of any of claims 15 to 17, wherein the de-clustering parameter comprises an inter-cluster interference level threshold.

19. The method of any of claims 15 to 18, wherein the de-clustering parameter comprises a coordination latency threshold.

20. The method of any of claims 15 to 19, further comprising:

receiving at least one reconfigured de-clustering parameter, and

determining, based at least in part on the at least one reconfigured de-clustering parameter, whether to join another cluster.

21. The method of any of claims 15 to 20, further comprising causing, subsequent to joining the second cluster, an indication of a cluster change event to be transmitted.

22. The method of claim 21, wherein the indication of the cluster change event comprises at least one of an indication of a cluster ID of the second cluster or an indication of a cluster size of the second cluster.

23. The method of claim 21 , wherein the cluster ID is assigned by a macro AP.

24. The method of claim 21, wherein the cluster ID is assigned using at least one Global eNB ID of a pico AP within the second cluster.

25. The method of either of claims 21 or 22, wherein the indication of the cluster change event comprises an ENB CONFIGURATION UPDATE message.

26. The method of any of claims 15 to 25, wherein the clustering parameter is mapped to the at least one de-clustering parameter.

27. The method of claim 26, further comprising:

determining, in an instance in which it is determined to join another cluster, at least one new clustering parameter based at least in part on the at least one de-clustering parameter; and wherein joining the second cluster based at least in part on the at least one clustering parameter comprises joining the second cluster based at least in part on the at least one new clustering parameter.

28. The method of any of claims 15 to 26, wherein the clustering parameter comprises a coupling loss threshold.

29. An apparatus comprising at least one processor and at least one memory storing program code instructions, the at least one memory and program code instructions being configured to, with the at least one processor, direct the apparatus to at least:

communicate with at least a first and second pico access point included in a first cell cluster;

determine at least one de-clustering parameter;

cause the at least one de-clustering parameter to be transmitted to at least one of the first or second pico access points included in the first cell cluster; and

communicate, subsequent to causing the at least one de-clustering parameter to be transmitted, with at least the first and second pico access points, the first pico access point being included in a second cell cluster and the second pico access point being included in a third cell cluster.

30. The apparatus of claim 29, wherein the de-clustering parameter comprises a cluster-size threshold.

31. The apparatus of either of claims 29 or 30, wherein the de-clustering parameter comprises a cluster traffic load threshold.

32. The apparatus of any of claims 29 to 31, wherein the de-clustering parameter comprises an inter-cluster interference level threshold.

33. The apparatus of any of claims 29 to 32, wherein the de-clustering parameter comprises a coordination latency threshold.

34. The apparatus of any of claims 29 to 33, the apparatus being further directed to:

reconfiguring the at least one de-clustering parameter, and

35. The apparatus of any of claims 29 to 34, the apparatus being further directed to receive an indication of a cluster change event.

36. The apparatus of claim 35, wherein the indication of the cluster change event comprises at least one of an indication of a cluster ID or an indication of a cluster size.

37. The apparatus of claim 36, wherein the apparatus is further directed to assign the cluster ID.

38. The apparatus of claim 36, wherein the cluster ID is assigned using at least one Global eNB ID of a pico AP within a cluster corresponding to the cluster ID.

39. The apparatus of either of claims 35 or 36, wherein the indication of the cluster change event comprises an ENB CONFIGURATION UPDATE message.

40. The apparatus of any of claims 29 to 39, the apparatus being further directed to cause a clustering parameter to be communicated to at least one of the first or second pico access points.

41. The apparatus of claim 40, wherein the clustering parameter is mapped to the at least one de-clustering parameter.

42. The apparatus of either of claims 40 or 41, wherein the clustering parameter comprises a coupling loss threshold.

43. An apparatus comprising at least one processor and at least one memory storing program code instructions, the at least one memory and program code instructions being configured to, with the at least one processor, direct the apparatus to at least:

receive at least one clustering parameter and at least one de-clustering parameter; join, based at least in part on the at least one clustering parameter, a first cell cluster; determine, based at least in part on the at least one de-clustering parameter, whether to join another cluster; and

join, based at least in part on the at least one clustering parameter, a second cluster in an instant in which it is determined to join another cluster.

44. The apparatus of claim 43, wherein the de-clustering parameter comprises a cluster-size threshold.

45. The apparatus of either of claims 43 or 44, wherein the de-clustering parameter comprises a cluster traffic load threshold.

46. The apparatus of any of claims 43 to 45, wherein the de-clustering parameter comprises an inter-cluster interference level threshold.

47. The apparatus of any of claims 43 to 46, wherein the de-clustering parameter comprises a coordination latency threshold.

48. The apparatus of any of claims 43 to 47, wherein the apparatus is further directed to: receiving at least one reconfigured de-clustering parameter, and

49. The apparatus of any of claims 43 to 48, wherein the apparatus is further directed to cause, subsequent to joining the second cluster, an indication of a cluster change event to be transmitted.

50. The apparatus of claim 49, wherein the indication of the cluster change event comprises at least one of an indication of a cluster ID of the second cluster or an indication of a cluster size of the second cluster.

51. The apparatus of claim 50, wherein the cluster ID is assigned by a macro AP.

52. The apparatus of claim 50, wherein the cluster ID is assigned using at least one Global eNB ID of a pico AP within the second cluster.

53. The apparatus of either of claims 49 or 50, wherein the indication of the cluster change event comprises an ENB CONFIGURATION UPDATE message.

54. The apparatus of any of claims 43 to 53, wherein the clustering parameter is mapped to the at least one de-clustering parameter.

55. The apparatus of claim 54, wherein the apparatus is further directed to:

determine, in an instance in which it is determined to join another cluster, at least one new clustering parameter based at least in part on the at least one de-clustering parameter; and wherein the apparatus is directed to join the second cluster based at least in part on the at least one clustering parameter by joining the second cluster based at least in part on the at least one new clustering parameter.

56. The apparatus of any of claims 43 to 55, wherein the clustering parameter comprises a coupling loss threshold.

57. A computer program product comprising at least one non-transitory computer-readable medium having program code portions embodied therein, the program code portions being configured to, upon execution, cause an apparatus to at least:

determine at least one de-clustering parameter;

58. The computer program product of claim 57, wherein the de-clustering parameter comprises a cluster-size threshold.

59. The computer program product of either of claims 57 or 58, wherein the de-clustering parameter comprises a cluster traffic load threshold.

60. The computer program product of any of claims 57 to 59, wherein the de-clustering parameter comprises an inter-cluster interference level threshold.

61. The computer program product of any of claims 57 to 60, wherein the de-clustering parameter comprises a coordination latency threshold.

62. The computer program product of any of claims 57 to 61, the apparatus being further directed to:

reconfiguring the at least one de-clustering parameter, and

63. The computer program product of any of claims 57 to 62, the apparatus being further directed to receive an indication of a cluster change event.

64. The computer program product of claim 63, wherein the indication of the cluster change event comprises at least one of an indication of a cluster ID or an indication of a cluster size.

65. The computer program product of claim 64, wherein the apparatus is further directed to assign the cluster ID.

66. The computer program product of claim 64, wherein the cluster ID is assigned using at least one Global eNB ID of a pico AP within a cluster corresponding to the cluster ID.

67. The computer program product of either of claims 63 or 64, wherein the indication of the cluster change event comprises an ENB CONFIGURATION UPDATE message.

68. The computer program product of any of claims 57 to 67, the apparatus being further directed to cause a clustering parameter to be communicated to at least one of the first or second pico access points.

69. The computer program product of claim 68, wherein the clustering parameter is mapped to the at least one de-clustering parameter.

70. The computer program product of either of claims 68 or 69, wherein the clustering parameter comprises a coupling loss threshold.

71. A computer program product comprising at least one non-transitory computer-readable medium having program code portions embodied therein, the program code portions being configured to, upon execution, cause an apparatus to at least:

receive at least one clustering parameter and at least one de-clustering parameter;

join, based at least in part on the at least one clustering parameter, a first cell cluster; determine, based at least in part on the at least one de-clustering parameter, whether to join another cluster; and

72. The computer program product of claim 71 , wherein the de-clustering parameter comprises a cluster-size threshold.

73. The computer program product of either of claims 71 or 72, wherein the de-clustering parameter comprises a cluster traffic load threshold.

74. The computer program product of any of claims 71 to 73, wherein the de-clustering parameter comprises an inter-cluster interference level threshold.

75. The computer program product of any of claims 71 to 74, wherein the de-clustering parameter comprises a coordination latency threshold.

76. The computer program product of any of claims 71 to 75, wherein the apparatus is further directed to:

receiving at least one reconfigured de-clustering parameter, and

77. The computer program product of any of claims 71 to 76, wherein the apparatus is further directed to cause, subsequent to joining the second cluster, an indication of a cluster change event to be transmitted.

78. The computer program product of claim 77, wherein the indication of the cluster change event comprises at least one of an indication of a cluster ID of the second cluster or an indication of a cluster size of the second cluster.

79. The computer program product of claim 78, wherein the cluster ID is assigned macro AP.

80. The computer program product of claim 78, wherein the cluster ID is assigned using at least one Global eNB ID of a pico AP within the second cluster.

81. The computer program product of either of claims 77 or 78, wherein the indication of the cluster change event comprises an ENB CONFIGURATION UPDATE message.

82. The computer program product of any of claims 71 to 81, wherein the clustering parameter is mapped to the at least one de-clustering parameter.

83. The computer program product of claim 82, wherein the apparatus is further directed to: determine, in an instance in which it is determined to join another cluster, at least one new clustering parameter based at least in part on the at least one de-clustering parameter; and wherein the apparatus is directed to join the second cluster based at least in part on the at least one clustering parameter by joining the second cluster based at least in part on the at least one new clustering parameter.

84. The computer program product of any of claims 71 to 83, wherein the clustering parameter comprises a coupling loss threshold.