WO2014015504A1

WO2014015504A1 - Method and apparatus for reducing interference in a heterogenous network

Info

Publication number: WO2014015504A1
Application number: PCT/CN2012/079216
Authority: WO
Inventors: Lili Zhang; Tero Heikki Matti Henttonen; Haiming Wang; Wei Hong
Original assignee: Renesas Mobile Corporation
Priority date: 2012-07-26
Filing date: 2012-07-26
Publication date: 2014-01-30

Abstract

A method, apparatus, and computer program product are provided to reduce interference in a heterogeneous network. In the context of a method, a signal may be transmitted that includes at least first and second measurement subsets. The subsets respectively include indications of first and second resources and cell IDs, the first and second resources being orthogonal to one another and the first and second cell IDs being different from one another. In the context of another method, a signal may be transmitted that includes indications of at least first and second subframe pattern subsets, the first being subset of an almost blank subframe (ABS) pattern that is orthogonal to one or more subframe pattern subsets adopted by one or more neighboring pico cells and the second being a subset of the ABS pattern that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells.

Description

METHOD AND APPARATUS FOR REDUCING INTERFERENCE IN A

HETEROGENOUS NETWORK

TECHNOLOGICAL FIELD

[0001] An example embodiment of the present invention relates generally to wireless networks and, more particularly, to reducing interference in Heterogeneous Networks (HetNets).

BACKGROUND

[0002] In heterogeneous networks including both macro and pico cells, there may be scenarios in which multiple pico cells overlap. In such a scenario, a user equipment (UE) that is located in the overlapping area of two or more pico cells may suffer severe interference from the adjacent, e.g., neighboring, pico cells. This interference can cause issues with measurements, such as radio resource management (RRM) measurements, or channel state information measurements, as well as complicating cell-specific reference signal (CRS) interference cancellation.

[0003] This interference may not be able to be avoided unless orthogonal almost blank subframe (ABS) patterns are adopted by the pico access points, but configuring totally orthogonal ABS patterns for the adjacent pico cells can be quite difficult for the macro cell, especially when the adjacent pico cells are under heavy load. Thus, effective ways to combat interference in a heterogeneous network are needed in order to ameliorate the above mentioned issues, as well as others.

BRIEF SUMMARY

[0004] Therefore, a method, apparatus, and computer program product are provided according to an example embodiment in order to reduce interference in a heterogeneous network. In this regard, the method, apparatus, computer program product, and system may provide signaling to enhance measurement mechanisms in a HetNet, such as by reducing interference. The method, apparatus, computer program product, and system may also provide enhance cell-specific reference signal (CRS) interference cancelation signaling, to improve CRS interference cancelation in a HetNet, thereby reducing interference. The various embodiments thus provide effective and flexible interference mitigation techniques which may be beneficial in various deployment scenarios.

[0005] In one embodiment, a method is provided that includes causing a signal to be transmitted, the signal comprising at least a first and second measurement subset. The first measurement subset includes an indication of a first resource and an indication of a first cell

ID, and the second measurement subset includes an indication of a second resource that is orthogonal to the first resource and an indication of a second cell ID that is different from the first cell ID. According to another embodiment, the signal may be caused to be transmitted in response to determining that a user equipment (UE) is approaching two or more neighboring pico cells.

[0006] In a further embodiment, a method is provided that includes receiving a signal comprising at least a first and second measurement subset. The first measurement subset includes an indication of a first resource and an indication of a first cell ID, and the second measurement subset includes an indication of a second resource that is orthogonal to the first resource and an indication of a second cell ID that is different from the first cell ID.

According to another embodiment, one or more measurements may be caused to be performed on a first pico cell corresponding to the first cell ID using the first resource, and on a second pico cell corresponding to the second cell ID using the second resource.

[0007] In another embodiment, a method is provided that includes causing a signal to be transmitted, the signal comprising indications of at least first and second subframe pattern subsets. The first subframe pattern subset includes a subset of an almost blank subframe (ABS) pattern that is orthogonal to one or more subframe pattern subsets adopted by one or more neighboring pico cells. The second subframe pattern subset includes a subset of the ABS pattern that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells. According to another embodiment, the signal may be caused to be transmitted in response to determining that a UE is in range of two pico cells which overlap. According to a further embodiment, the signal may be caused to be transmitted in response to determining that a UE is approaching two or more neighboring pico cells. According to yet another embodiment, the signal may be caused to be transmitted in response to determining that a pico cell serving a UE overlaps with a neighboring pico cell. [0008] In a further embodiment, a method is provided that includes receiving a signal comprising indications of at least first and second subframe pattern subsets. The first subframe pattern subset includes a subset of an almost blank subframe (ABS) pattern that is orthogonal to one or more subframe pattern subsets adopted by one or more neighboring pico cells. The second subframe pattern subset includes a subset of the ABS pattern that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells. According to another embodiment, channel state information (CSI) measurements may be caused to be performed using one or more of the subframe pattern subsets. According to another embodiment, cell-specific reference signal (C S) interference cancellation may be caused to be performed in one or more of the subframe pattern subsets.

[0009] In another embodiment, an apparatus is provided that includes at least one processor and at least one memory storing program code instruction therein, the at least one memoiy and program code instructions being configured to, with the at least one processor, cause the apparatus to at least cause a signal to be transmitted, the signal comprising at least a first and second measurement subset. The first measurement subset includes an indication of a first resource and an indication of a first cell ID, and the second measurement subset includes an indication of a second resource that is orthogonal to the first resource and an indication of a second cell ID that is different from the first cell ID. According to another embodiment, the apparatus may be caused to cause the signal to be transmitted in response to determining that a user equipment (UE) is approaching two or more neighboring pico cells.

[0010] In a further embodiment, an apparatus is provided that includes at least one processor and at least one memory storing program code instruction therein, the at least one memory and program code instructions being configured to, with the at least one processor, cause the apparatus to at least receive a signal comprising at least a first and second measurement subset. The first measurement subset includes an indication of a first resource and an indication of a first cell ID, and the second measurement subset includes an indication of a second resource that is orthogonal to the first resource and an indication of a second cell ID that is different from the first cell ID. According to another embodiment, the apparatus may be further caused to cause one or more measurements to be performed on a first pico cell corresponding to the first cell ID using the first resource, and on a second pico cell corresponding to the second cell ID using the second resource. [0011] In another embodiment, an apparatus is provided that includes at least one processor and at least one memory storing program code instruction therein, the at least one memory and program code instructions being configured to, with the at least one processor, cause the apparatus to at least cause a signal to be transmitted, the signal comprising indications of at least first and second subframe pattern subsets. The first subframe pattern subset includes a subset of an almost blank subframe (ABS) pattern that is orthogonal to one or more subframe pattern subsets adopted by one or more neighboring pico cells. The second subframe pattern subset includes a subset of the ABS pattern that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells. According to another embodiment, the apparatus may be caused to cause the signal to be transmitted in response to determining that a UE is in range of two pico cells which overlap. According to a further embodiment, the apparatus may be caused to cause the signal to be transmitted in response to determining that a UE is approaching two or more neighboring pico cells.

According to yet another embodiment, the apparatus may be caused to cause the signal to be transmitted in response to determining that a pico cell serving a UE overlaps with a neighboring pico cell.

[0012] In a further embodiment, an apparatus is provided that includes at least one processor and at least one memory storing program code instruction therein, the at least one memory and program code instructions being configured to, with the at least one processor, cause the apparatus to at least receive a signal comprising indications of at least first and second subframe pattern subsets. The first subframe pattern subset includes a subset of an almost blank subframe (ABS) partem that is orthogonal to one or more subframe pattern subsets adopted by one or more neighboring pico cells. The second subframe pattern subset includes a subset of the ABS pattern that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells. According to another embodiment, the apparatus may be caused to cause channel state information (CSI) measurements to be performed using one or more of the subframe pattern subsets. According to another embodiment, the apparatus may be caused to cause cell-specific reference signal (CRS) interference cancellation may to be performed in one or more of the subframe pattern subsets.

[0013] 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 cause a signal to be transmitted, the signal comprising at least a first and second measurement subset. The first measurement subset includes an indication of a first resource and an indication of a first cell ID, and the second measurement subset includes an indication of a second resource that is orthogonal to the first resource and an indication of a second cell

ID that is different from the first cell ID. According to another embodiment, the apparatus may be further caused to cause the signal to be transmitted in response to determining that a user equipment (UE) is approaching two or more neighboring pico cells.

[0014] 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 cause the apparatus to at least receive a signal comprising at least a first and second measurement subset. The first measurement subset includes an indication of a first resource and an indication of a first cell ID, and the second measurement subset includes an indication of a second resource that is orthogonal to the first resource and an indication of a second cell ID that is different from the first cell ID. According to another embodiment, the apparatus may be further caused to cause one or more measurements to be performed on a first pico cell corresponding to the first cell ID using the first resource, and on a second pico cell corresponding to the second cell ID using the second resource.

[0015] 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 cause a signal to be transmitted, the signal comprising indications of at least first and second subframe pattern subsets. The first subframe pattern subset includes a subset of an almost blank subframe (ABS) pattern that is orthogonal to one or more subframe pattern subsets adopted by one or more neighboring pico cells. The second subframe pattern subset includes a subset of the ABS pattern that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells. According to another embodiment, the apparatus may be caused to cause the signal to be transmitted in response to determining that a UE is in range of two pico cells which overlap. According to a further embodiment, the apparatus may be caused to cause the signal to be transmitted in response to determining that a UE is approaching two or more neighboring pico cells. According to yet another embodiment, the apparatus may be caused to cause the signal to he transmitted in response to determining that a pico cell serving a UE overlaps with a neighboring pico cell.

[0016] 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 a signal comprising indications of at least first and second subframe pattern subsets. The first subframe pattern subset includes a subset of an almost blank subframe (ABS) partem that is orthogonal to one or more subframe pattern subsets adopted by one or more neighboring pico cells. The second subframe pattern subset includes a subset of the ABS pattern that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells. According to another embodiment, the apparatus may be caused to cause channel state information (CSI) measurements to be performed using one or more of the subframe pattern subsets. According to another embodiment, the apparatus may be caused to cause cell- specific reference signal (C S) interference cancellation may to be performed in one or more of the subframe pattern subsets.

[0017] In another embodiment, an apparatus is provided that includes means for causing a signal to be transmitted, the signal comprising at least a first and second measurement subset. The first measurement subset includes an indication of a first resource and an indication of a first cell ID, and the second measurement subset includes an indication of a second resource that is orthogonal to the first resource and an indication of a second cell ID that is different from the first cell ID. According to another embodiment, the apparatus may further include means for causing the signal to be transmitted in response to detennining that a user equipment (UE) is approaching two or more neighboring pico cells.

[0018] In a further embodiment, and apparatus is provided that includes means for receiving a signal comprising at least a first and second measurement subset. The first measurement subset includes an indication of a first resource and an indication of a first cell ID, and the second measurement subset includes an indication of a second resource that is orthogonal to the first resource and an indication of a second cell ID that is different from the first cell ID. According to another embodiment, the apparatus may further include means for causing one or more measurements to be performed on a first pico cell corresponding to the first cell ID using the first resource, and on a second pico cell corresponding to the second cell ED using the second resource.

[0019] In another embodiment, an apparatus is provided that includes means for causing a signal to be transmitted, the signal comprising indications of at least first and second subframe pattern subsets. The first subframe pattern subset includes a subset of an almost blank subframe (ABS) pattern that is orthogonal to one or more subframe pattern subsets adopted by one or more neighboring pico cells. The second subframe pattern subset includes a subset of the ABS pattern that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells. According to another embodiment, the apparatus may further include means for causing the signal to be transmitted in response to determining that a UE is in range of two pico cells which overlap. According to a further embodiment, the apparatus may further include means for causing the signal to be transmitted in response to determining that a UE is approaching two or more neighboring pico cells. According to yet another embodiment, the apparatus may further include means for causing the signal to be transmitted in response to determining that a pico cell serving a UE overlaps with a neighboring pico cell.

[0020] In a further embodiment, an apparatus method is provided that includes means for receiving a signal comprising indications of at least first and second subframe pattern subsets. The first subframe pattern subset includes a subset of an almost blank subframe (ABS) pattern that is orthogonal to one or more subframe pattern subsets adopted by one or more neighboring pico cells. The second subframe pattern subset includes a subset of the ABS pattern that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells. According to another embodiment, the apparatus may include means for causing channel state information (CSI) measurements to be performed using one or more of the subframe pattern subsets. According to another embodiment, the apparatus may include means fir causing cell-specific reference signal (CRS) interference cancellation to be performed in one or more of the subframe pattern subsets. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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:

[0022] Figure 1 is an illustration of a system that may benefit from example

embodiments of the present invention;

[0023] Figure 2 is a block diagram of an apparatus that may be configured in accordance with an example embodiment of the present invention; and

[0024] Figures 3-7 are flowcharts illustrating operations performed in accordance with an example embodiment of the present invention.

DETAILED DESCRIPTION

[0025] 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.

[0026] 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 processors) 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.

[0027] 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 a server, a cellular network device, or other network device.

[0028] Referring now to Figure 1, a heterogeneous network (Het et) is depicted. As used herein, a HetNet refers to any network consisting of multiple types of access points, such as one or more macro access points serving one or more macro cells, and one or more pico access points serving one or more pico cells. A macro cell covers a larger area than a pico cell, and therefore is ordinarily served by a macro access point transmitting at a higher power than a pico access point in the same HetNet. The HetNet depicted in Figure 1 may support communications between a user equipment, such user equipment 10, 11, or 12, 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 100, 110, and 120 is shown. As shown in Figure 1, the HetNet includes a macro cell 101, provided by macro access point 100; a first pico cell 111, provided by a first pico access point 110; and a second pico cell 121, provided by a second pico access point 120. Jagged double-sided arrows between a UE and an access point indicate that that UE is connected to, e.g., being served by, that access point. A dotted- line arrow indicates movement in space. As used herein, an access point refers to any communication device which provides connectivity to a network, such as 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 any of UEs 10, 11, or 12 and any of access points 100, 110, or 120 may include the transmission of data via an uplink that is granted between the user equipment 10, 11, or 12 and access point 100, 110 or 120.

[0029] UEs 10, 11, or 12 as well as access points 100, 110, or 120 may embody or otherwise be associated with an apparatus 20 that is generally depicted in Figure 2 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.

[0030] As shown in Figure 2, the apparatus 20 may include or otherwise be in communication with 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, such as in conjunction with Figures 3-7. 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.

[0031] 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 the processing circuitry may be embodied as a portion of the UE or access point, such as general purpose processing circuitry included therein.

[0032] 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 UE 10, 11, or 12 and access points 100, 110, or 120. In this regard, the communication interface may include, for example, an antenna (or multiple antennas), such as an antenna (or multiple antennas) capable of communicating over radio frequencies (RF), and supporting hardware and/or software, such as RF circuitry, for enabling communications with a wireless communication network. The communication interface 26 may also include a communication modem or other hardware/software for supporting communication via cable, digital subscriber line (DSL), universal serial bus (USB), Ethernet or other methods.

[0033] 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 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.

[0034] 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), DSP (digital signal processor), 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, DSP 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.

[0035] As mentioned in the Background, and as depicted in Figure 1, heterogeneous networks (HetNets) including macro 101 and pico 111, 121 cells can cause complex interference issues, such as when two or more pico cells are adjacent to one another or overlap, as pico cells 111 and 121 do in Figure 1. Although Figure 1 contains two pico cells, it should be understood that all discussion herein is just as applicable in scenarios with three or more pico cells. Broadly speaking, there are two interrelated interference issues that may arise in HetNet with two or more neighboring, e.g., adjacent, pico cells and which may be addressed by embodiments of the present invention. First, the interference can make it challenging for a UE in range of two or more neighboring pico cells, such as pico cell 111 and 121, to take measurements of those pico cells. Second, cell-specific reference signal (CRS) interference cancelation can become quite difficult to configure. These two interrelated issues will now be discussed in turn, along with embodiments of the present invention which may ameliorate or even eliminate these issues.

[0036] The problem of measurements in HetNets including two or more adjacent pico cells.

[0037] Referring back to Figure 1, a scenario is depicted in which with multiple pico cells, e.g., pico cells 111 and 121, are overlapping. In this case, UE 12, which is located in the overlapping area of two pico cells, may suffer from relatively severe interference from the two neighboring pico cells. Severe control channel interference in particular may be a concern and may not be avoided unless orthogonal almost blank subframe (ABS) patterns are adopted at pico access points 1 10 and 120.

[0038] However, if different, e.g., orthogonal, ABS patterns are required to be adopted by neighboring pico access points 110 and 120, a UE, such as UE 10, that is approaching both pico cell 110 and pico cell 121 should have different measurement subsets towards the neighboring pico cell 1 and 2. Otherwise, the measurement result may be severely corrupted by the neighboring pico access point transmissions. Moreover, a UE, such as UE 11, that is moving from pico cell 11 1 to pico cell 121, the serving cell (e.g., pico cell 111) measurement subset should be totally orthogonal to the neighboring cell (e.g., pico cell 121) measurement subset. No solution to either situation is provided by the current standards.

[0039] It is worth noting, however, that it may be quite difficult for a macro access point, such as macro access point 100, to configure the needed orthogonal ABS pattern for adjacent pico cells 111 and 121, especially when the pico cells are under heavy loads. Thus, overlapping ABS subframes may be used by neighboring pico cells during typical applications. Ordinarily, when an ABS patterns is being configured a more static second bitmap (or a subset of the second bit map) is recommended for radio link monitoring (RLM) or serving cell radio resource management (RRM) measurements, while more dynamic first bit map (or a subset of first bit map) is used for channel state information (CSI)

measurements. That is, the more static second bitmap that is used for neighboring cell measurement may be set as orthogonal, while the more dynamic first bit map that is used for CSI may be unorthogonal.

[0040] Thus, according to a first aspect of an example embodiment, multiple RRM resource restrictions may be configured for neighboring, e.g., overlapping, pico cells, such as pico cells 111 and 121, so that a UE, such as UE 10, that is approaching the neighboring cells may have correct knowledge of the measurement subframes. Thus, UE 10 may be permitted to use different, e.g., orthogonal, measurement subsets for each of the neighboring pico cells.

[0041] In this regard, and with reference to Figure 3, operations for configuring multiple RRM resource restrictions according to an embodiment are depicted. These operations may be performed by an apparatus, such as apparatus 20 as shown in Figure 2, embodied by or otherwise associated with a macro access point, such as macro access point 100 depicted in Figure 1. In this regard, the apparatus 20 may include means, such as the processor 22, memory 24, the communication interface 26 or the like, for causing a signal comprising at least first and second measurement subsets to be transmitted. See operation 320 of Figure 3. As noted above, embodiments of the present invention are equally applicable in situations in which 3 or more pico cells are neighboring to one another and, accordingly, the signal may further include additional measurement subsets corresponding to additional pico cells. In any event, each of the measurement subsets may include an indication of a resource and an indication of a cell ID linked to the resource. The indicated resources may be orthogonal to one another, and the cell ID may be different. As mentioned above, this embodiment may be of particular use in situations where a UE, such as UE 10, is approaching two or more neighboring pico cells, such as pico cells 111 and 121. Accordingly, the apparatus 20 may include means, such as the processor 22, memory 24, the communication interface 26 or the like, for determining when a UE is approaching two or more neighboring pico cells, and causing the aforementioned signal to be transmitted following, or in response to, to such a determination. See operation 310 of Figure 3. The apparatus 20 may, for example, determine that a UE is approaching two or more neighboring pico cells based on one or more reference signal receive power (RSRP) or reference signal receive quality (RSRQ) reports received from the UE. See operation 300 of Figure 3.

[0042] Referring for a moment to Figure 6, corresponding UE-side operations which may be performed by an apparatus, such as apparatus 20, embodied by or otherwise associated with a UE, such as UE 10, are depicted. In this regard, apparatus 20 may include means, such as the processor 22, memory 24, the communication interface 26 or the like, for receiving the above signal comprising at least a first and second measurement subset. See operation 620 of Figure 6. As discussed above, each of the measurement subsets may respectively include an indication of a resource and an indication of a cell ID linked to the resource, the indicated resources being orthogonal to one another, and the cell IDs being different from one another. Apparatus 20 may further include means, such as the processor 22, memory 24, the communication interface 26 or the like, for causing measurements, such as, for example, RRM measurements, to be performed on a first pico cell corresponding to a first cell ID using the indicated first resources associated with the first cell ID, and on a second pico cell corresponding to a second cell ID using the indicated second resources associated with the second cell ID. See operation 620 of Figure 6. As discussed above, these operations may, according to another example embodiment, be carried out similarly on a third, fourth, or more pico cell. The apparatus 20 associated with or otherwise embodied by a UE may also include means, such as the processor 22, memory 24, the communication interface 26 or the like, for causing one or more RSRP or RSRQ reports to be transmitted. See operation 600 of Figure 6. As discussed above, these reports may allow an access point to determine when the UE is approaching two neighboring pico cells.

[0043] Having discussed the above embodiments generally, discussion will now turn to a specific embodiment of the signal discussed above. In this regard, the signal discussed above, which may be caused to be transmitted by apparatus 20 associated with or otherwise embodied by an access point, such as macro access point 100, and which may be received by an apparatus 20 associated with or otherwise embodied by a UE, may, for example, include a easObjectEUTRA IE that includes the discussed indications. The indications of the first and second resources may, for example, be radio resource control (RRC) parameters or information elements (IE) for MeasSubframePatternConfigNeigh, such as

MeasSubframePatternConfigNeigh-rlO and MeasSubframePatternConfigNeigh-rl 1. The resource indicated by MeasSubframePattemConfigNeigh-rl 1 would thus be orthogonal to that indicated by MeasSubframePatternConfigNeigh-rlO. The indications of the first and second cell IDs may, for example, be RRC parameters or IEs for measSubframeCellList, such as measSubframeCellList-rl 0 and measSubframeCellList-r 11. The cell IDs indicated by measSubframeCellList-rl 1 would thus be different from that indicated by

measSubframeCellList- 10. An example implementation is provided below, in Appendix Al. Additions to the MeasObjectEUTRA IE, as it is defined in 3GPP 36.331, according to embodiments of the present invention are indicated with dotted outlines.

[0044] Thus, it will be appreciated that the above embodiments may allow a UE, such as

UE 10, which is coming into range of two neighboring pico cells, such as pico cell 110 and pico cell 120, to perform measurements, such as RRM measurements, on each of the neighboring pico cells with reduced interference by using orthogonal resources.

[0045] Turning now to a second aspect of an example embodiment, multiple CSI resource restrictions may additionally or alternatively be configured for neighboring pico cells, such as pico cells 111 and 121, so that a UE that is in range of two or more neighboring, e.g., overlapping, pico cells, may have correct knowledge of the channel state, so that it may, for example, properly perform modulation and coding scheme (MCS) selection. Thus, a UE, such as UE 11 or 12, which is in range of two or more neighboring pico cells, such as pico cells 111 and 121, may have access to multiple subframe pattern subsets for CSI reporting.

[0046] In this regard, and with reference to Figure 4, operations for configuring multiple

CSI resource restrictions according to an embodiment are depicted. These operations may be performed by an apparatus, such as apparatus 20 as shown in Figure 2, embodied by or otherwise associated with a pico access point, such as pico access point 110 or 120 depicted in Figure 1. In this regard, the apparatus 20 may include means, such as the processor 22, memory 24, the communication interface 26 or the like, for causing a signal comprising indications of at least first and second subframe pattern subsets to be transmitted. See operation 420 of Figure 3. The first subframe pattern subset may be a subset of an ABS pattern that is orthogonal, e.g., totally orthogonal, to one or more subframe pattern subsets adopted by one or more neighboring pico cells. The second subframe pattern subset may also be a subset of an ABS pattern, but one that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells. According to an example

embodiment, the first subframe pattern subset may, for example, be a static bitmap, while the second subframe pattern subset may be a dynamic bitmap minus the static bitmap. The signal may also, according to another example embodiment, include a third subframe pattern subset that is a subset of a non-ABS pattern. According to an additional example embodiment, the signal may further include indications of CSI report configuration information. Thus, the signal may include indications of at least two channel quality indicator (CQI) and pre-coding matric indicator (PMI) configuration indexes, indications of at least two rank indicator (RI) configuration indexes, and indications of at least two CSI reporting modes. Each of the subframe pattern subsets may be respectively associated with a set of CSI report parameters.

That is, each subframe pattern subset may be associated with: one of the at least two CQI and PMI configuration indexes, one of the at least two RI configuration indexes, and one of the at least two CSI reporting modes.

[0047] As mentioned above, the above embodiments may be of particular use in situations in which a UE, such as UE 1 1 or 12, is in range of two or more neighboring, e.g., overlapping, pico cells, such as pico cells 111 and 121. Accordingly, the apparatus 20 may, according to an example embodiment, include means, such as the processor 22, memory 24, the communication interface 26 or the like, for determining when a UE, such as UE 1 1 or 12, is in range of two or more overlapping pico cells, and causing the aforementioned signal to be transmitted following, or in response to, to such a determination. See operation 410 of Figure 4. The apparatus 20 may, for example, determine that a UE is in range of two or more overlapping pico cells based on one or more reference signal receive power (RSRP) or reference signal receive quality (RSRQ) reports received from the UE. See operation 400 of Figure 4.

[0048] Referring again for a moment to Figure 6, corresponding UE-side operations which may be performed by an apparatus, such as apparatus 20, embodied by or otherwise associated with a UE, such as UE 11 or 12, are depicted. In this regard, apparatus 20 may include means, such as the processor 22, memory 24, the communication interface 26 or the like, for receiving the above signal comprising indications of at least first and second subframe pattern subsets. See operation 630 of Figure 6. As discussed above, the signal may also comprise at third subframe pattern subset and may further comprise CSI report configuration information, such as indications of at least two channel quality indicator (CQI) and pre-coding matric indicator (PMI) configuration indexes, indications of at least two rank indicator (RI) configuration indexes, and indications of at least two CSI reporting modes. Each of the subframe pattern subsets may be respectively associated with a set of CSI report parameters, as discussed above. The apparatus 20 may further include means, such as the processor 22, memory 24, the communication interface 26 or the like, for causing CSI measurements to be performed using one or more of the subframe subset patterns. See operation 640 of Figure 6. The apparatus 20 associated with or otherwise embodied by a UE may also include means, such as the processor 22, memory 24, the communication interface 26 or the like, for causing one or more RSRP or RSRQ reports to be transmitted. See operation 600 of Figure 6. As discussed above, these reports may allow an access point to determine when the UE is in range of two or more overlapping pico cells.

[0049] Having discussed the above embodiments generally, discussion will again turn to a specific embodiment of the signal discussed above. In this regard, the signal discussed above, which may be caused to be transmitted by apparatus 20 associated with or otherwise embodied by an access point, such as pico access point 110 or 120, and which may be received by an apparatus 20 associated with or otherwise embodied by a UE, may, for example, include a CQI-ReportConfig IE that includes the discussed indications. The indications of the subframe subset patterns may, for example, be RRC parameters or IEs for csi-SubframePatternConfig-rl 1, such as: csi-MeasSubframeSetl-rl 1, which may indicate the ABS pattern subset which is orthogonal to that adopted by the one or more neighboring pico cells; csi-MeasSubframeSet2-rl 1, which may indicate the ABS pattern subset which overlaps with that adopted by one or more neighboring pico cells; and, for embodiments in which the signal includes a third subframe pattern subset, csi-MeasSubframeSet3-rl 1, which may indicate a subset of a non-ABS pattern. The indications of the CSI report configuration information may include RRC parameters or IEs for csi-Configlndex. For example, the at least two CQI and PMI configuration indexes may be indicated by two or more indexes of cqi-pmi-Configlndex, the indications of at least two RI configuration indexes may be indicated by ri-Configlndex, and the indications of at least two CSI reporting modes may be indicated by csi-ReportMode-rl 1. An example implementation of the above is provided below, in Appendix A2. Additions to the CQI-ReportConfig IE, as it is defined in 3GPP

36.331, according to embodiments of the present invention are indicated with dotted outlines.

[0050] Thus, it will be appreciated that the above embodiments may allow a UE, such as UE 11 or 12, which is in range of two overlapping pico cells, such as pico cell 110 and pico cell 120, to perform measurements, such as CSI measurements, on each of the neighboring pico cells with reduced interference by using one or more ABS pattern subsets.

[0051] The problem of CRS interference cancelation in HetNets including two or more neighboring pico cells.

[0052] Again referring back to Figure 1, for a UE, such as UE 11 or 12, that is in communication with, e.g., being served by, a pico cell, such as pico cell 111 or 121, the UE may need the aggressor cell's (the cell causing CRS interference) information to perform CRS interference cancellation. However, it may be difficult for a UE to promptly perform CRS interference cancellation based only on normal CRS assistance information, such as cell ID, antenna ports number, and MBSFN (multicast-broadcast single frequency network) configuration of the neighboring aggressor cell. Thus, it may be beneficial for the UE to receive certain additional information to assist in CRS interference cancelation. [0053] There are two cases related to CRS interference cancellation which are illustrated in Figure 1 and may be treated differently according to example embodiments of the present invention. In the first case, a UE, such as UE 12, may be located in the overlapped region between two pico cells, such as pico cell 111 and 121. Because UE 12 is located in the overlapped area of two neighboring pico cells, it may be desirable for UE 12 to be scheduled in the totally orthogonal ABS subset, and to perform CRS interference cancellation for both the macro cell 100 and the neighboring pico access point, either pico access point 110 or 120, depending on which is currently serving the UE. That is, if UE 12 is being served by pico cell 121, it may perform CRS interference cancellation for both macro cell 100 and pico cell 111. In the second case, a UE, such as UE 11 , may be located in the non-overlap ed pico CRE region. Because UE 11 is located in the unoverlapped region, it may be desireable for UE 11 to be scheduled in the non-orthogonal ABS subset, and to perform CRS interference cancellation only for the macro cell.

[0054] Thus, according to an example embodiment, multiple subframe subsets may be provided to a UE. One or more of the subsets may be associated with one or more cell IDs.

The UE may determine what the dominating interference source is, and then perform CRS interference cancellation in the subframe subset corresponding to the associated dominating interference source based on the CRS information from the dominant interfering source.

[0055] Turning now to Figures 5a and 5b, operations performed by an apparatus 20, embodied by or otherwise associated with an access point, for providing enhanced CRS assistance signaling to a UE that it is serving are depicted. In this regard, Figure 5a represents operations performed by an apparatus 20 embodied by or otherwise associated with a macro access point, such as access point 100, while Figure 5b represents operations performed by an apparatus 20 embodied by or otherwise associated with a pico access point, such as access point 110 or 120. Thus, the apparatus 20 may include means, such as the processor 22, memory 24, the communication interface 26 or the like, for causing a signal comprising indications of at least first and second subframe pattern subsets to be transmitted. See operation 520 of Figures 5a and 5b. As with the subframe pattern subsets included in the signal discussed above, the subframe pattern subsets of this signal may include a first subset of an ABS pattern that is orthogonal, e.g., totally orthogonal, to one or more subframe pattern subsets adopted by one or more neighboring pico cells and a second subset of an ABS pattern that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells. According to an example embodiment, the signal may include one or more cell IDs, e.g., in a list, that are associated with one or more of the subframe pattern subsets. Thus, as discussed further below, this may allow a UE that receives the signal to, after determining one or more dominant interference sources, perform CRS interference in the appropriate subframe subset which corresponds with the cell ID(s) of the dominant interfering source(s). According to an alternative embodiment, the cell ID(s) of the dominant interfering source(s) may be signaled together with the individual subframe subsets. That is, one or more subframe subset may be signaled, each being associated with the cell ID(s) of their corresponding dominant interfering source(s), such that the UE will know in which subframe subset to perform CRS interference cancelation for the corresponding cell ID. According to yet another embodiment, dedicated signaling may be used to provide CRS assistance information for different UEs in CRE areas, e.g., some may be in an overlapping area of two pico cells, some may not be. The dedicated signaling may be differentiated due to the different CRS cancelation requirements of the UEs in different CRE areas.

[0056] As depicted in Figures 5a and 5b, the triggering condition for transmitting this signal may depend on whether apparatus 20 is embodied by or otherwise associated with a macro access point, such as macro access point 100, or a pico access point, such as pico access points 110 or 120. Referring to Figure 5a, an apparatus 20 embodied by or otherwise associated with a macro access point, such as macro access point 100, may include means, such as the processor 22, memory 24, the communication interface 26 or the like, for determining whether a UE is approaching two or more neighboring, e.g., overlapping, pico cells. See operation 510 of Figure 5a. Thus, apparatus 20 may cause the signal to be transmitted following, or in response to, making such a determination. Referring to Figure 5b, an apparatus 20 embodied by or otherwise associated with a pico access point serving a UE, such as pico access point 120, may include means, such as the processor 22, memory 24, the communication interface 26 or the like, for determining whether the pico cell provided by the pico access point overlaps with one or more neighboring pico cells. See operation 515 of Figure 5b. Thus, apparatus 20 may cause the signal to be transmitted following, or in response to, making such a determination. For either of the embodiments just discussed, apparatus 20 may include means, such as the processor 22, memory 24, the communication interface 26 or the like, for making the determination on the basis of one or more received RSRP or RSRQ reports. See operation 500 of Figures 5a and 5b.

[0057] Turning now to Figures 6 and 7, corresponding UE-side operations which may be performed by an apparatus, such as apparatus 20, embodied by or otherwise associated with a UE, such as UE 10, 11 or 12, are depicted. In this regard, apparatus 20 may include means, such as the processor 22, memory 24, the communication interface 26 or the like, for receiving the above signal comprising indications of at least first and second subframe pattern subsets. See operation 630 of Figure 6. As discussed above, one or more of the subframe pattern subsets may be associated with one or more cell IDs. Apparatus 20 may further include means, such as the processor 22, memory 24, the communication interface 26 or the like, for causing CRS interference cancellation to be performed. See operation 650 of Figure 6. This operation is shown in more detail in Figure 7. In this regard, apparatus 20 may further include means, such as the processor 22, memory 24, the communication interface 26 or the like, for detenninmg the dominant interfering source(s). See operation 700 of Figure 7. That is, the apparatus 20 may determine whether it is experiencing interference from the macro cell 101 only, or from a macro and pico cell. For example, UE 11 would only experience interference from macro cell 101, while UE 12 would experience interference from macro cell 101 as well as pico cell 111. Thus, having determined the dominant source(s) of interference, the apparatus 20 may cause appropriate CRS interference cancellation to be performed. See operations 710 and 720 of Figure 7. That is, apparatus 20 may perform CRS interference for the dominating interference source(s) in the subframe pattern subset associated with the cell ID(s) of the dominating interference source(s), as indicated in the signal. Thus, as an example, in an instance in which both a macro and neighboring pico cell are the dominant interfering sources, apparatus 20 may cause CRS interference cancellation to be performed for both the macro cell and the neighboring pico cell in the first subframe pattern subset, which is an ABS pattern subset that is orthogonal to the subframe pattern subsets adopted by any neighboring pico cells. In an instance in which only the macro cell is the dominant interfering source, apparatus 20 may cause CRS interference cancellation to be performed for the macro cell in the second subframe pattern subset, which is an ABS pattern subset that overlaps with that adopted by any neighboring pico cells. An added benefit of the above embodiments are that a UE that has received one or more ABS pattern subsets in which CRS interference cancellation should be done may use this to implicitly derive the ABS configurations that are being used by itself and its cell.

[0058] Having discussed the above embodiments generally, discussion will now turn to a specific embodiment of the signal discussed above. In this regard, the signal discussed above, which may be caused to be transmitted by apparatus 20 associated with or otherwise embodied by an access point, such as macro access point 100, and which may be received by an apparatus 20 associated with or otherwise embodied by a UE, may, for example, include a MeasObjectEUTRA IE that includes the discussed indications. An example implementation of the above is provided below, in Appendix A3. Additions to the MeasObjectEUTRA IE, as it is defined in 3 GPP 36.331, according to embodiments of the present invention are indicated with dotted outlines.

[0059] Embodiments according to the invention may provide many benefits in a wireless communication system. For example, embodiments according to the invention may provide enhancements to neighboring cell measurement mechanisms which may effectively prevent measurement errors in HetNets caused by interference when a UE served by a macro cell is approaching two overlapping pico cells or a UE served by a pico cell is moving towards another neighboring pico cell that overlaps with the serving pico cell. Embodiments according to the invention may also provide enhancements to CSI measurement mechanisms which provide accurate channel state information and MCS determinations for a pico UE that is close to the overlapped area of two neighboring pico cells. Further embodiments may provide prompt, flexible CRS interference cancellation that is effective in multiple dominant interference source scenarios. Embodiments may provide enhanced assistance information for CRS interference cancellation that may effectively deal with the problem of unprompt CRS interference cancellation during different serving cell/neighboring cell measurements as well CSI/RLF reporting.

[0060] 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.

APPENDIX

Al:

MeasObjectEUTRA information element

-- ASN1START

MeasObj ectEUTRA : : = SEQUENCE {

carrierFreq ARFCN-ValueEUTRA,

allowedMeasBandwidth AllowedMeasBandwidth,

presenceAnteniiaPortl PresenceAnteniiaPortl,

neighCellConfig NeighCellConfig,

offsetFreq Q-OffsetRange DEFAULT dBO,

-- Cell list

cellsToRemoveList CelllndexList OPTIONAL, -- Need ON CellsToAddModList CellsToAddModList OPTIONAL, -- Need ON -- Black list

blackCellsToRetnoveList CelllndexList OPTIONAL, -- Need ON blackCellsToAddModiist BlackCellsToAddModList OPTIONAL, -- Need ON cellForWhichToReportCGI PhysCellld OPTIONAL, -- Need ON

[ [measCycleSCell-rlO MeasCycleSCell-rlO OPTIONAL, -- Need ON measSubframePatternConfigNeigh-rlO MeasSubframePatternConfigNeigh-rlO OPTIONAL

-- Need ON

measSubf amePatternConfigNeigh-rll MeasSubframePatternConfigNeigh-rll OPTIONAL

-- Need ON

]]

CellsToAddModList ::= SEQUENCE (SIZE (1.. maxCellMeas) ) OF CellsToAddMod

CellsToAddMod ;:= SEQUENCE {

celllndex INTEGER (l..maxCellMeas) ,

physCellld PhysCellld,

celllndividualOffset Q-OffsetRange

BlackCellsToAddModList SEQUENCE (SIZE ( 1..maxCellMeas) ) OF BlackCellsToAddMod

BlackCellsToAddMod ::= SEQUENCE (

celllndex INTEGER (1.. maxCellMeas)

physCellldRange PhysCellldRange

}

RRM-ResourceRestrictionConfig-rlO SEQUENCE {

rm-ResourceRes riction-r10 TimeDomainResourceRestriction-rl0 ,

resourceRestrictionCellList ResourceRestrictionCellList-rlO OPTIONAL Need OR

)

ResourceRestrictionCellList-rlO ::- SEQUNCE (SIZE (1 , .maxCellMeas) ) OF PhysCellldRange

MeasSubframePatternConfigNeigh-rlO ;:= CHOICE {

release NULL,

setup SEQUENCE {

measSubframePatternNeigh-rlO MeasSubframePattern-rlO ,

measSubframeCellList-rlO MeasSubframeCellList-rlO OPTIONAL Need

OP

}

} easSubframeCellList-rlO ::= SEQUENCE (SIZE (1..maxCellMeas) ) OF PhysCellldRange

MeasSubframePatternConfigNeigh-rll ::= CHOICE {

release NULL,

setup SEQUENCE {

measSubframePa ternNeigh-rll MeasSubframePattern-rll,

measSubframeCellList-rll MeasSubframeCellList-rll OPTIONAL -- Need

OP

}

MeasSubframeCellList-rll :;= SEQUENCE (SIZE (l..maxCellMeas) ) OF PhysCellldRange

- ASN1STOP

MeasObjectEUTRA field descriptions carrierFreq

Identifies E-UTRA carrier frequency for which this configuration is valid. offsetFreq

Offset value applicable to the carrier frequency. Value dB-24 corresponds to -24 dB, dB- 22 corresponds to -22 dB and so on. cellsToRemoveList

List of cells to remove from the cell list. cellsToA ddModList

List of cells to add/ modify in the cell list. celllndex

Entry index in the cell list. An entry may concern a range of cells, in which case this value applies to the entire range. physCellld

Physical cell identity of a cell in the cell list. eel tin dividualOffse t

Cell individual offset applicable to a specific cell. Value dB-24 corresponds to -24 dB, dB-22 corresponds to -22 dB and so on. blackCells ToRemoveList

List of cells to remove from the black list of cells. blackCellsToAddMoList

List of cells to add/ modify in the black list of cells. physCe!l!dRange

Physical cell identity or a range of physical cell identities of cells in the black list.

A2:

CQI-ReportConfig information elements

ASNISTART

CQI-ReportConfig ::= SEQUENCE {

cqi-ReportModeAperiodic CQI-ReportModeAperiodic OPTIONAL, Need OR nomPDSCH-RS-EPRE-Offset INTEGER (-1..6),

cqi-Repor Periodic CQI-ReportPeriodic OPTIONAL Need ON

}

CQI-ReportConfig-v920 ::= SEQUENCE {

cqi-Mask-r9 ENUMERATED {setup} OPTIONAL, Cond cqi-Setup pmi-RI-Report-r9 ENUMERATED {setup} OPTIONAL Cond PMIEI

}

CQI-ReportConfig-rlO SEQUENCE {

cqi-ReportAperiodic-r10 CQI-ReportAperiodic-r10 OPTIONAL, - - Need ON nomPDSCH-RS-EPRE-Offset INTEGER (-1..6),

cqi-ReportPeriodic- lO CQI- eportPeriodic-rl0 OPTIONAL, - - Need ON pmi-RI-Report-r9 ENUMERATED {setup} OPTIONAL, - - Cond PMIRI csi-SubframePatternConfig-rlO CHOICE {

release NULL,

setup SEQUENCE {

csi-MeasSubframeSetl-rlO MeasSubframePattern- no.

csi-MeasSubframeSet2 -rlO MeasSubframePattem- no

}

!

csi-SubframePatternConfig-rll CHOICE {

release NULL,

setup SEQUENCE {

csi-MeasSubframeSetl-rll MeasSubframePattern-no,

csi-MeasSubframeSet2-rll MeasSubframePattern-no.

csi-MeasSubframeSet3-rll MeasSubframePattern- rlO

}

OPTIONAL Need ON

}

CQl-ReportConfigSCell-rlO SEQUENCE {

cqi-ReportModeApe iodic-r10 CQI-ReportModeAperiodic OPTIONAL, Need OR nomPDSCH-RS-EPRE-Offset-rlO INTEGER (-1..6) ,

cqi- eportPe iodicSCell-rlO CQI-ReportPeriodic-rlO OPTIONAL, Need ON pmi-RI-Report-rlO ENUMERATED {setup} OPTIONAL Cond PMIRI

}

CQI-ReportPeriodic ::= CHOICE

release NULL,

setup SEQUENCE {

cqi-PUCCH-Resourcelndex INTEGER (0..1185) ,

cqi-pmi-Configlndex INTEGER (0..1023) ,

cqi-FormatlndicatorPeriodic CHOICE {

widebandCQI NULL,

subbandCQI SEQUENCE {

k INTEGER (1..4) ri-Configlndex INTEGER (0..1023) OPTIONAL, Need

OR

simultaneousAckNackAndCQI BOOLEAN

}

CQI-ReportPeriodic-rlO ::= CHOICE {

release NULL,

setup SEQUENCE {

cqi-PUCCH-ResourceIndex-r10 INTEGER (0..1184) , cqi-PUCCH-ResourcelndexPl-rlO INTEGER (0..1184) OPTIONAL, Need

OR

cqi-pmi-Configlndex INTEGER {0..1023),

cqi-FormatlndicatorPeriodic-rlO CHOICE {

widebandCQI-r10 SEQUENCE {

csi-ReportMode- l0 ENUMERATED {submodel, s bmode2} OPTIONAL Need

OR

subbandCQI- lO SEQUENCE {

k INTEGER (1..4) ,

periodic!tyFactor-r10 ENUMERATED {n2, n4 }

}

h

ri-Configlndex INTEGER (0..1023) OPTIONAL, Need

OR

simultaneousAckNackAndCQI BOOLEAN,

cqi-Mask-r9 ENUMERATED {setup} OPTIONAL, - - Need

OR

-Configlndex-rlO CHOICE {

release NULL,

setup SEQUENCE {

cqi-pmi-Configlndex - INTEGER (0..1023) ,

ri-Configlndex2-rl0 INTEGER (0..1023) OPTIONAL Need

OR

}

OPTIONAL Need

ON

}

CQI-ReportPeriodic-rll CHOICE {

release NULL,

setup SEQUENCE {

cqi-PUCCH-ResourceIndex- ll INTEGER :0..1184)

cqi-PUCCH- esou ceIndexPl-r11 INTEGER ID..1184) OPTIONAL, Need

OR

cqi-pmi-Configlndex INTEGER (0..1023),

cqi-FormatlndicatorPeriodic-rll CHOICE {

widebandCQI-r11 SEQUENCE {

csi-ReportHode-rll ENUMERATED {submodel, submode2, submode3 } OPTIONAL

Need OR

}- subbandCQI- l1 SEQUENCE {

k INTEGER {1..4) ,

periodicityFactor- rll ENUMERATED {n2, n4 }

}

}.

ri-Configlndex INTEGER (0..1023) OPTIONAL, Need

OR

simultaneousAckNackAndCQX BOOLEAN,

cqi-Mask-r9 ENUMERATED {setup} OPTIONAL, - - Need

OR

csi-Configlndex-rll CHOICE {

release NULL,

setup SEQUENCE {

cqi-pmi-Configlndex3 -rll INTEGER .1023) ,

ri-Configlndex3-rll INTEGER .1023) OPTIONAL Need

OR

}

OPTIONAL Need

ON

}

CQI-ReportAperiodic-rlO ::= CHOICE {

release NULL,

setup SEQUENCE {

cqi-ReportModeAperiodic-rlO ENUMERATED {

rml2, rm20, rm22, rm30, rm31,

spare3, spare2, sparel}. aperiodicCSI-Trigger SEQUENCE {

triggerl-ΠΟ BIT STRING {SIZE (8) )

trigger2-rl0 BIT STRING (SIZE ( B) )

} OPTIONAL Need

OR

)

}

CQI-ReportModeAperiodic ::= ENUMERATED {

rml2, rm20, rm22, rm30, rm31.

spare3 , spare2 , sparel

ASN1STOP

CQI-ReportConfig field descriptions aperiodicCSI- Trigger

indicates for which serving cell(s) the aperiodic CSI report is triggered when one or more SCells are configured, triggerl corresponds to the CSI request field 10 and trigger2 corresponds to the CSI request field 1 1, see TS 36.213 [23, table 7.2.1-1 A]. The leftmost bit, bit 0 in the bit string corresponds to the cell with ServCelllndex=0 and bit 1 in the bit string corresponds to the cell with ServCelllndex^ etc. Each bit has either value 0 (means no aperiodic CSI report is triggered) or value 1 (means the aperiodic CSI report is triggered). At most 5 bits can be set to value 1 in the bit string. One value apples for all serving cells (the associated functionality is common i.e. not performed independently for each cell). cqi-Mask

Limits CQI/PMl/PTl/RI reports to the on-duration period of the DRX cycle, see TS 36.321 [6]. One value apples for all serving cells (the associated functionality is common i.e. not performed independently for each cell). csi-Configlndex

E-UTRAN configures csi-Configlndex only for PCell and only if csi- SubframePatternConfig is configured. csi-ReportMode

Parameter: PUCCH_format1-1_CSI_reporting_mode, see TS 36.213 [23, 7.2.2]. cqi-Format!ndicatorPeriodic

Parameter: PUCCH CQI Feedback Type, see TS 36.213 [23, table 7.2.2-1], Depending on transmissionMode, reporting mode is implicitly given from the table. cqi-pmi-Configlndex

Parameter: CQI/PMI Periodicity and Offset Configuration Index ICQI/PMI, see TS 36.213 [23, tables 7.2.2-1 A and 7.2.2-1 C]. If subframe patterns for CSI (CQI/PMI/PTI/RI) reporting are configured (i.e. csi-SubframePatternConfig is configured), the parameter applies to the subframe pattern corresponding to_csi-MeasSubframeSet1. cqi-pmi-Configlndex2

Parameter: CQI/PMI Periodicity and Offset Configuration Index ICQI/PMI, see TS 36.213 [23, tables 7.2.2-1 A and 7.2.2-1 C]. The parameter applies to the subframe pattern corresponding to csi-MeasSubframeSet2. CQI-ReportConfig field descriptions cqi-pmi-Configlndex3

Parameter: CQI/PMI Periodicity and Offset Configuration Index ICQI/PMI, see TS 36.213 [23, tables 7.2.2-1 A and 7.2.2-1 C]. The parameter applies to the subframe pattern corresponding to csi-MeasSubframeSet3. cqi-PUCCH-Resourcelndex, cqi-PUCCH-ResourcelndexP1

Parameter UCCH for antenna port P0 and for antenna port P1 respectively, see TS 36.213 [23, 7.2]. E-UTRAN does not apply value 1185. cqi-ReportModeAperiodic

Parameter: reporting mode. Value rm12 corresponds to Mode 1-2, rm20 corresponds to Mode 2-0, rm22 corresponds to Mode 2-2 etc. PUSCH reporting modes are described in TS 36.213 [23, 7.2.1].

K

Parameter: K, see TS 36.213 [23, 7.2.2]. nomPDSCH-RS-EPRE-Offset

Parameter: A_offset see TS 36.213 [23, 7.2.3]. Actual value = IE value ^* 2 [dB].

periodicityFactor

Parameter: W , see TS 36.2 3 [23, 7.2.2]. pmi-Rl-Report

See TS 36.213 [23, 7.2]. The presence of this field means PMI/RI reporting is configured; otherwise the PMI/RI reporting is not configured. EUTRAN configures this field only when transmissionMode is set to tm8 or tm9. ri-Configlndex

Parameter: Rl Config Index l_RI, see TS 36.213 [23, 7.2.2-1 B]. If subframe patterns for CSI (CQI/PMI/PTI/RI) reporting are configured (i.e. csi-SubframePatternConfig is configured), the parameter applies to the subframe pattern corresponding to_cs/^'- MeasSubframeSetl . CQI-ReportConfig field descriptions ri- Configlndex2

Parameter: RI Config Index IRI, see TS 36.213 [23, 7.2.2-1 B]. The parameter applies to the subframe pattern corresponding to_csi-MeasSubframeSet2. E-UTRAN configures ri- Configlndex2 only if ri-Configlndex is configured. ri-Configlndex3

Parameter: RI Config Index IRI, see TS 36.213 [23, 7.2.2-1 B]. The parameter applies to the subframe pattern corresponding to_csi-MeasSubframeSet2. E-UTRAN configures ri- Configindex3 only if ri-Configlndex is configured. simultaneousAckNackAndCQI

Parameter: Simultaneous-AN-and-CQI, see TS 36.213 [23, 10.1] TRUE indicates that simultaneous transmission of ACK/NACK and CQI is allowed. For SCells this field is not applicable and the UE shall ignore the value.

A3:

MeasObjectEUTRA information element

MeasOb ectEUTHA : : = SEQUENCE {

carrierFreq ARFCN-ValueEUTRA,

allowedMeasBandwidth AllowedMeasBandwidth,

presenceAntennaPortl PresenceAntennaPortl,

neighCellConfig NeighCellConfig,

offsetFreq Q-OffsetRange DEFAULT dBO,

-- Cell list

blackCelIsToRemoveList CelllndexList OPTIONAL, -- Need ON blackCellsToAddModList BlackCellsToAddModList OPTIONAL, -- Need ON cellForWhichToReportCGI PhysCellld OPTIONAL, -- Need ON

[ imeasCycleSCell-rlO MeasCycleSCell-rlO OPTIONAL, -- Need ON measSubfratnePattemConfigNeigh-rlO MeasSubframePatternConfigNeigh-rlO OPTIONAL

-- Need ON

1!

[ [crslnterferenceHandlinglnformation-rll NeighCellCRSInfo-rll OPTIONAL

Cond felCIC

])

CellsToAddModList SEQUENCE (SIZE (1..maxCellMeas) ) OF CellsToAddMod

CellsToAddMod : : = SEQUENCE

celllndex INTEGER {1..maxCellMeas) ,

physCellld PhysCellld,

celllndividualOffset Q-OffsetRange

1

BlackCellsToAddModList : : = SEQUENCE (SIZE (1.. maxCellMeas) ) OF BlackCellsToAddMod

BlackCellsToAddMod : SEQUENCE {

celllndex INTEGER ( 1..maxCellMeaS) ,

PhysCellldRange PhysCellldRange

}

MeasCycleSCell-rlO : ENUMERATED {sfl60, sf25S, sf320, s£512,

sf640, sfl024, sfl280, sparel}

MeasSubframePatteriiCon£igNeigh-rlO :: :: = CHOICE {

release NULL,

setup SEQUENCE {

measSubframePatternNeigh-rlO MeasSubfraraePattern-rlO ,

measSubframeCellList-rlO MeasSubframeCellList-rlO OPTIONAL Cond measSubframe

}

MeasSubframeCellList-rlO ::= SEQUENCE (SIZE (1..maxCellMeas) ) OF PhysCellldRange

; NeighCellCRSInfo-rll ::= SEQUENCE (SIZE (1.. maxCelllntra) ) OF NeighCellCRSConfig j NeighCellCRSConfig : : = SEQUENCE {

• physCellld-rll PhysCellld,

I antennaPortsCount-rll ENUMERATED {anl, an2, an4, sparel),

! mbsfn-SubframeConfigList-rll MBSFN-S bframeConf gList

; AppliableMeasSubframePatternConfigNeigh ENUMERATED

! { MeasSubframePatternConfigNeigh-rlO, MeasSubfratnePattemConfigNeigh-rll} ,

j AppllableCsi-SubframePatternConfig ENUMERATED { csi-MeasSubframeSetl-rll, csi-

; MeasSubframeSet2-rll, csi-MeasSubframeSet3-rll },

: }

ASNISTOP MeasObjectEUTRA field descriptions blackCellsToAddMoList

List of cells to add/ modify in the black list of cells. blackCellsToRemoveList

List of cells to remove from the black list of cells. carrierFreq

Identifies E-UTRA carrier frequency for which this configuration is valid. celllndex

Entry index in the cell list. An entry may concern a range of cells, in which case this value applies to the entire range. celllndividualOffset

Cell individual offset applicable to a specific cell. Value dB-24 corresponds to -24 dB, dB-22 corresponds to -22 dB and so on. cells To Add Mo dUst

List of cells to add/ modify in the cell list. cells ToRemo veList

List of cells to remove from the cell list. crslnterferenceHandlinglnformation

Information about cells for which UE can apply receiver-based techniques when felCIC is configured. measCycleSCell

Parameter: T_measure_scc See TS 36.133 [16, 8.3.3]. The parameter is used only when an SCell is configured on the frequency indicated by the measObject and is in deactivated state, but the field may also be signalled when an SCell is not configured. Value sf160 corresponds to 160 sub-frames, sf256 corresponds to 256 sub-frames and so on. MeasObjectEUTRA field descriptions measSubframeCellList

List of cells for which measSubframePatternNeigh is applied. measSubframePatternNeigh

Time domain measurement resource restriction pattern applicable to neighbour cell RSRP and RSRQ measurements on the carrier frequency indicated by carrierFreq. For cells in measSubframeCellList the UE shall assume that the subframes indicated by measSubframePatternNeigh are non- BSFN subframes.

NeighCellCRSConfig

Information about a neighbor cell CRS configuration. The UE can use this information to handle the CRS interference from the indicated neighbor cells for RRM/RLM

measurements using measurement resource restriction configured by,

measSubframePatternConfigNeigh-r10/r11. The UE can also use the information for CQI reporting of subframes configured in various cs SubframeSet. The corresponding CRS interference cancellation at measSubframePatternPCell can be determined by judging its overlapped set with various csi-SubframeSet and consistent with that done in csi- SubframeSet. offsetFreq

Offset value applicable to the carrier frequency. Value dB-24 corresponds to -24 dB, dB- 22 corresponds to -22 dB and so on. physCellld

Physical cell identity of a cell in the cell list. physCellldRange

Conditional Explanation

presence measSubframe The field is mandatory present if measSubframePatternNeigh is configured. felCIC The field is mandatory present if measSubframePatternPCell,

measSubframePatternNeigh or csi-SubframeSet2 is configured.

Claims

WHAT IS CLAIMED IS:

1. A method comprising:

causing a signal to be transmitted, the signal comprising at least a first and second measurement subset, the first measurement subset comprising an indication of a first resource and an indication of a first cell ID and the second measurement subset comprising an indication of a second resource and an indication of a second cell ID;

wherein the first resource is orthogonal to the second resource and the first cell ID is different from the second cell ID.

2. The method of claim 1, wherein the signal comprises a MeasObjectEUTRA information element (IE) and the indications are included in the MeasObjectEUTRA IE.

3. The method of either of claims 1 or 2, wherein the indications of the first and second resources respectively comprise:

a MeasSubframePatternConfigNeigh-rlO IE or radio resource control (RRC) parameter, and

a MeasSubframePatternConfigNeigh-rl 1 IE or RRC parameter.

4. The method of any of claims 1 to 3, wherein the indications of the first and second cell IDs respectively comprise:

a MeasSubframeCellList-rlO IE or RRC parameter, and

a MeasSubframeCellList-rl 1 IE or RRC parameter.

5. The method of any of claims 1 to 4, further comprising:

receiving a reference signal receive power (RSRP) report or reference signal receive quality (RSRQ) report, and

determining the first and second resources based on the received report.

6. A method comprising: causing a signal to be transmitted, the signal comprising indications of at least first and second subframe pattern subsets;

wherein:

the first subframe pattern subset comprises a subset of an almost blank subframe (ABS) pattern that is orthogonal to one or more subframe pattern subsets adopted by one or more neighboring pico cells, and

the second subframe pattern subset comprises a subset of the ABS pattern that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells.

7. The method of claim 6, wherein the first subframe pattern subset comprises a static bitmap and the second subframe pattern subset comprises a dynamic bitmap minus the static bitmap.

8. The method of either of claims 6 or 7, wherein the signal further comprises a third subframe pattern subset comprising a subset of a non-ABS pattern.

9. The method of any of claims 6 to 8, wherein the signal further comprises:

indications of at least two channel quality indicator (CQI) and pre-coding matrix indicator (PMI) configuration indexes,

indications of at least two rank indicator (RI) configuration indexes, and

indications of at least two channel state information (CSI) reporting modes;

wherein each of the subframe pattern subsets is respectively associated with:

one of the at least two CQI and PMI configuration indexes,

one of the at least two RI configuration indexes, and

one of the at least two CSI reporting modes.

10. The method of any of claims 6 to 9, wherein the signal comprises a csi- SubfraniePatternConfig-rl 1 IE and a csi-Configlndex-rl 1 IE, and further wherein:

the indications the subframe pattern subsets are included in the SubframePattemConfig rl 1 IE, and the indications of the at least three channel quality indicator (CQI) and pre-coding matrix indicator (PMI) configuration indexes and the indications of the at least three rank indicator (RI) configuration indexes are included in the csi-Configlndex-rl 1 IE.

11. The method of any of claims 1 to 10, further comprising detecting that a user equipment (UE) is approaching two or more of the neighboring pico cells;

wherein causing the signal to be transmitted comprises causing the signal to be transmitted in response to detecting that the UE is approaching two or more neighboring pico cells.

12. The method of claim 11 , further comprising receiving a reference signal receive power (RSRP) report or reference signal receive quality (RSRQ) report;

wherein detecting that the UE is approaching two or more of the neighboring pico cells comprises determining whether the UE is approaching two or more of the neighboring pico cells based on the received report.

13. The method of any of claims 6 to 10, further comprising detecting that a pico cell in communication with a UE overlaps with one or more of the neighboring pico cells;

wherein causing the signal to be transmitted comprises causing the signal to be transmitted in response to detecting that the pico cell in communication with the UE overlaps with one or more of the neighboring pico cells.

14. The method of claim 13, wherein at least one of the subframe pattern subsets is associated with one or more cell IDs.

15. The method of either of claims 13 or 14, further comprising receiving a RSRP report or RSRQ report;

wherein detecting that the pico cell in communication with the UE overlaps with one or more of the neighboring pico cells comprises determining whether the pico cell in

communication with the UE overlaps with one or more of the neighboring pico cells based on the received report.

16. The method of any of claims 13 to 15, wherein the signal comprises a first signal, and further comprising causing a second signal to be transmitted, wherein the second signal: comprises CRS assistance information,

is transmitted via direct signaling to a second UE, and

is differentiated from the first signal.

17. A method comprising:

receiving a signal comprising at least a first and second measurement subset, the first measurement subset comprising an indication of a first resource and an indication of a first cell ID and the second measurement subset comprising an indication of a second resource and an indication of a second cell ID, wherein the first resource is orthogonal to the second resource and the first cell ID is different from the second cell ID.

18. The method of claim 17, further comprising:

causing one or more measurements to be performed using the first resource on a first pico cell corresponding to the first cell ID; and

causing one or more measurements to be performed using the second resource on a second pico cell corresponding to the second cell ID.

19. The method of either of claims 17 or 18, wherein the signal comprises a

MeasObjectEUTRA information element (IE) and the measurement subsets are included in the MeasObjectEUTRA IE.

20. The method of any of claims 17 to 19, wherein the indications of the first and second resources respectively comprise:

a MeasSubframePattemConfigNeigh-rl 1 IE or RRC parameter.

21. The method of any of claims 17 to 20, wherein the indications of the first and second cell IDs respectively comprise:

a MeasSubframeCellList-rlO IE or RRC parameter, and

a MeasSubframeCellList-rl 1 IE or RRC parameter.

22. The method of any of claims 17 to 21, further comprising:

causing a reference signal receive power (RSRP) report or reference signal receive quality (RSRQ) report to be sent prior to receiving the signal.

23. The method of any of claims 17 to 22, wherein the first and second pico cells are overlapping.

24. A method comprising:

receiving a signal comprising indications of at least first and second subframe pattern subsets, wherein:

the first subframe pattern subset comprises a subset of an almost blank subframe (ABS) pattern that is orthogonal to subframe pattern subsets adopted by one or more neighboring pico cells, and

the second subframe pattern subset comprises a subset of the ABS pattern that is overlapped with subframe pattern subsets adopted by one or more neighboring pico cells.

25. The method of claim 24, wherein the first subframe pattern subset comprises a static bitmap and the second subframe pattern subset comprises a dynamic bitmap minus the static bitmap.

26. The method of either of claims 24 or 25, wherein the signal comprises a third subframe pattern subset comprising a subset of a non-ABS pattern.

27. The method of any of claims 24 to 26, wherein the signal further comprises: indications of at least three channel quality indicator (CQI) and pre-coding matrix indicator (PMI) configuration indexes,

indications of at least three rank indicator (RI) configuration indexes, and indications of at least three channel state information reporting modes;

wherein each of the subframe pattern subsets is respectively associated with:

one of the at least three channel quality indicator (CQI) and pre-coding matrix indicator (PMI) configuration indexes,

one of the at least three rank indicator (RI) configuration indexes, and one of the at least three channel state information reporting modes.

28. The method of any of claims 24 to 27, wherein the signal comprises a csi- SubframePatternConfig-rl 1 IE and a csi-Configlndex-rl 1 IE, and further wherein:

the indications the subframe pattern subsets are included in the SubframePatternConfig- rl 1 IE, and

the indications of the at least three channel quality indicator (CQI) and pre-coding matrix indicator (PMI) configuration indexes and the indications of the at least three rank indicator (RI) configuration indexes are included in the csi-Configlndex-rl 1 IE.

29. The method of any of claims 24 to 28, further comprising:

30. The method of any of claims 24 to 29, further comprising causing one or more channel state information (CSI) measurements to be performed using one or more of the subframe pattern subsets.

31. The method of any of claims 24 to 30, further comprising causing cell-specific reference signal (CRS) interference cancellation to be performed in one or more of the subframe pattern subsets.

32. The method of claim 31, wherein causing cell-specific reference signal interference cancellation to be performed in one or more of the subframe pattern subsets comprises: detennining whether CRS interference cancellation should be performed for a macro cell only or whether CRS interference cancellation should be performed for both the macro cell and one or more of the neighboring pico cells;

in an instance in which CRS interference cancellation should be performed for the macro cell only, causing CRS interference cancellation to be performed for the macro cell in the second subframe pattern subset; and

in an instance in which CRS interference cancellation should be performed for both the macro cell and one or more of the neighboring pico cells, causing CRS interference cancellation to be performed for the macro cell and one or more of the neighboring pico cells in the second sub frame p attern subset.

33. The method of either of claims 31 or 32, wherein at least one of the subframe pattern subsets is associated with at least one respective cell ID.

34. The method of any of claims 31 to 33, further comprising receiving CRS assistance information from a dominating interference source; wherein causing CRS interference cancellation to be performed for a cell comprises causing CRS interference cancellation to be performed using the received CRS assistance information.

35. The method of any of claims 24 to 34, further comprising deriving an ABS configuration being used by a UE or a cell that is serving the UE based on the received signal.

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

cause a signal to be transmitted, the signal comprising at least a first and second measurement subset, the first measurement subset comprising an indication of a first resource and an indication of a first cell ID and the second measurement subset comprising an indication of a second resource and an indication of a second cell ID;

37. The apparatus of claim 36, wherein the signal comprises a MeasObjectEUTRA information element (IE) and the indications are included in the MeasObjectEUTRA IE.

38. The apparatus of either of claims 36 or 37, wherein the indications of the first and second resources respectively comprise:

a MeasSubframePatternConfigNeigh-rl 1 IE or RRC parameter.

39. The apparatus of any of claims 36 to 38, wherein the indications of the first and second cell IDs respectively comprise:

a MeasSubframeCellList-rlO IE or RRC parameter, and

a MeasSubframeCellList-rl 1 IE or RRC parameter.

40. The apparatus of any of claims 36 to 39, wherein the apparatus is further caused to:

receive a reference signal receive power (RSRP) report or reference signal receive quality (RSRQ) report, and

determine the first and second resources based on the received report.

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

cause a signal to be transmitted, the signal comprising indications of at least first and second subframe pattern subsets;

wherein:

the first subframe pattern subset comprises a subset of an almost blank subframe (ABS) pattern that is orthogonal to one or more subframe pattern subsets adopted by one or more neighboring pico cells, and the second subframe pattern subset comprises a subset of the ABS pattern that overlaps with one or more subframe pattern subsets adopted by one or more neighboring pico cells.

42. The apparatus of claim 41, wherein the first subframe pattern subset comprises a static bitmap and the second subframe pattern subset comprises a dynamic bitmap minus the static bitmap.

43. The apparatus of either of claims 41 or 42, wherein the signal further comprises a third subframe pattern subset comprising a subset of a non-ABS pattern.

44. The apparatus of any of claims 41 to 43, wherein the signal further comprises: indications of at least two channel quality indicator (CQI) and pre-coding matrix indicator (PMI) configuration indexes,

indications of at least two rank indicator (RI) configuration indexes, and

indications of at least two channel state information (CSI) reporting modes;

wherein each of the subframe pattern subsets is respectively associated with:

one of the at least two CQI and PMI configuration indexes,

one of the at least two RI configuration indexes, and

one of the at least two CSI reporting modes.

45. The apparatus of any of claims 41 to 44, wherein the signal comprises a csi- SubframePatternConfig-rl 1 IE and a csi-Configlndex-rl I IE, and further wherein:

46. The apparatus of any of claims 35 to 45, wherein the apparatus is further caused to detect that a user equipment (UE) is approaching two or more of the neighboring pico cells; wherein the apparatus is caused to cause the signal to be transmitted in response to detecting that the UE is approaching two or more neighboring pico cells.

47. The apparatus of claim 46, wherein the apparatus is further caused to receive a reference signal receive power (RSRP) report or reference signal receive quality (RSRQ) report; wherein the apparatus is caused to detect that the UE is approaching two or more of the neighboring pico cells by determining whether the UE is approaching two or more of the neighboring pico cells based on the received report.

48. The apparatus of any of claims 41 to 45, further comprising detecting that a pico cell in communication with a UE overlaps with one or more of the neighboring pico cells;

wherein the apparatus is caused to cause the signal to be transmitted in response to detecting that the pico cell in communication with the UE overlaps with one or more of the neighboring pico cells.

49. The apparatus of claim 48, wherein at least one of the subframe pattern subsets is associated with one or more cell IDs.

50. The apparatus of either of claims 48 or 49, wherein the apparatus is further caused to receive an RSRP report or an RSRQ report;

51. The apparatus of any of claims 48 to 50, wherein the signal comprises a first signal, and further comprising causing a second signal to be transmitted, wherein the second signal:

comprises CRS assistance information,

is transmitted via direct signaling to a second UE, and

is differentiated from the first signal.

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

receive a signal comprising at least a first and second measurement subset, the first measurement subset comprising an indication of a first resource and an indication of a first cell ID and the second measurement subset comprising an indication of a second resource and an indication of a second cell ID, wherein the first resource is orthogonal to the second resource and the first cell ID is different from the second cell ID.

53. The apparatus of claim 52, wherein the apparatus is further caused to:

cause one or more measurements to be performed using the first resource on a first pico cell corresponding to the first cell ID; and

cause one or more measurements to be performed using the second resource on a second pico cell corresponding to the second cell ID.

54. The apparatus of either of claims 52 or 53, wherein the signal comprises a MeasObjectEUTRA information element (IE) and the measurement subsets are included in the MeasObjectEUTRA IE.

55. The apparatus of any of claims 52 to 54, wherein the indications of the first and second resources respectively comprise:

a MeasSubframePattemConfigNeigh-rlO IE or radio resource control (RRC) parameter, and

a MeasSubframePatternConfigNeigh-rl 1 IE or RRC parameter.

56. The apparatus of any of claims 52 to 55, wherein the indications of the first and second cell IDs respectively comprise:

a MeasSubframeCellList-rlO IE or RRC parameter, and

a MeasSubframeCellList-rl 1 IE or RRC parameter.

57. The apparatus of any of claims 52 to 56, wherein the apparatus is further caused to:

cause a reference signal receive power (RSRP) report or reference signal receive quality (RSRQ) report to be sent prior to receiving the signal.

58. The apparatus of any of claims 52 to 57, wherein the first and second pico cells are overlapping.

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

receive a signal comprising indications of at least first and second subframe pattern subsets, wherein:

60. The apparatus of claim 59, wherein the first subframe pattern subset comprises a static bitmap and the second subframe pattern subset comprises a dynamic bitmap minus the static bitmap.

61. The apparatus of either of claims 59 or 60, wherein the signal comprises a third subframe pattern subset comprising a subset of a non-ABS pattern.

62. The apparatus of any of claims 59 to 61, wherein the signal further comprises: indications of at least three channel quality indicator (CQI) and pre- coding matrix indicator (PMI) configuration indexes,

indications of at least three rank indicator (RI) configuration indexes, and

indications of at least three channel state information reporting modes;

wherein each of the subframe pattern subsets is respectively associated with: one of the at least three channel quality indicator (CQI) and pre-coding matrix indicator (PMI) configuration indexes,

63. The apparatus of any of claims 59 to 62, wherein the signal comprises a csi- SubframePatternConfig-rl 1 IE and a csi-Configlndex-rl 1 IE, and further wherein:

64. The apparatus of any of claims 59 to 63, wherein the apparatus is further caused to:

cause a reference signal receive ower (RSRP) report or reference signal receive quality (RSRQ) report to be sent prior to receiving the signal.

65. The apparatus of any of claims 59 to 64, wherein the apparatus is further caused to cause one or more channel state information (CSI) measurements to be performed using one or more of the subframe pattern subsets.

66. The apparatus of any of claims 59 to 65, wherein the apparatus is further caused to cause cell-specific reference signal (CRS) interference cancellation to be performed in one or more of the subframe pattern subsets.

67. The apparatus of claim 66, wherein the apparatus is caused to cause cell-specific reference signal interference cancellation to be performed in one or more of the subframe pattern subsets by: determining whether CRS interference cancellation should be performed for a macro cell only or whether CRS interference cancellation should be performed for both the macro cell and one or more of the neighboring pico cells;

in an instance in which CRS interference cancellation should be performed for both the macro cell and one or more of the neighboring pico cells, causing CRS interference cancellation to be performed for the macro cell and one or more of the neighboring pico cells in the second subframe pattern subset.

68. The apparatus of either of claims 66 or 67, wherein at least one of the subframe pattern subsets is associated with at least one respective cell ID.

69. The apparatus of any of claims 66 to 68, wherein the apparatus is further caused to receive CRS assistance information from a dominating interference source; wherein causing CRS interference cancellation to be performed for a cell comprises causing CRS interference cancellation to be performed using the received CRS assistance information.

70. The apparatus of any of claims 59 to 69, further comprising deriving an ABS configuration being used by a UE or a cell that is serving the UE based on the received signal.

71. A computer program product comprising a non-transitory computer readable storage medium storing program code portions therein, the program code portions being configured to, upon execution, cause an apparatus to perform the method according to any of claims 1 to 35.