WO2015120305A1 - Improving naics dci reception - Google Patents

Abstract

Various communication systems may benefit from improved reception of downlink control information. For example, long term evolution advanced (LTE- Advanced or LTE-A) may benefit, particularly with respect to the operation of advanced receivers which are associated with network aided interference cancellation and suppression (NAICS). A method can include transmitting, to a user equipment, parameters comprising a cell identifier of a cell transmitting network aided interference cancellation and suppression downlink control information. The method can also include transmitting downlink control information consistent with the parameters.

Description

TITLE:

Improving NAICS DCI Reception

CROSS-REFERENCE TO RELATED APPLICATIONS:

[0001] This application relates to and claims the benefit and priority of U.S. Provisional Patent Application No. 61/937,181 filed February 7, 2014, the entirety of which is hereby incorporated herein by reference.

BACKGROUND:

Field:

[0002] Various communication systems may benefit from improved reception of downlink control information. For example, long term evolution advanced (LTE- Advanced or LTE-A) may benefit, particularly with respect to the operation of advanced receivers which are associated with network aided interference cancellation and suppression (NAICS).

Description of the Related Art:

[0003] In network assisted interference cancellation and suppression, there is interest in as-yet unknown signaling schemes that would enable the UE to utilize more advanced receivers for interference cancellation or suppression. In the following, the advanced receiver performing interference cancellation can be referred to as NAICS user equipment (UE). Targeted deployment scenarios include evolved Node B (eNB) scenarios where the eNBs are connected by a non- ideal backhaul with a high latency and low capacity. At the same time, suitable schemes should also work in single eNB and other cases where the different transmitting nodes may be connected by an ideal backhaul, with close to zero latency and high capacity.

[0004] In general, interference can be created by the data traffic of the UEs as well as common signals and channels transmitted in a cell. Hence there are multiple interference forms: inter-stream interference due to the non-orthogonality of spatial multiple input multiple output (MIMO) streams dedicated to the same UE, which can be called single user MIMO (SU-MIMO) interference; and inter-user interference which can arise between users served in the same cell and sharing the same resources, which can be called multiple user MIMO (MU-MIMO) interference. In addition, interference can happen among UEs located in different cells, which can be referred to as inter-cell interference. UEs located at the cell edge may particular suffer from inter-cell interference. Canceling inter-cell interference may greatly improve both the cell capacity and coverage. On the other hand, sending the information characterizing the aggressor interference structure to the victim becomes non-trivial as the aggressor is located in a neighboring cell controlled by one eNB, while the victim is located in another cell potentially controlled by another eNB.

[0005] The NAICS UE may get signaled some assistance information which provides the NAICS UE with certain parameters characterizing the interference. These parameters may permit more efficient and less complex cancellation or suppression of the interference by the NAICS UE receiver. Such parameters may include for instance (not an exhaustive list): parameters about common reference signal (CRS) transmission including multicast-broadcast single-frequency network (MBSFN) subframes, number of CRS ports, cell ID, and parameters P_A and P_B controlling the physical downlink shared channel (PDSCH) power relative to CRS power; and parameters depending on dynamic scheduling decisions including rank indicator, transmission mode, precoding matrix indicator, resource allocation, modulation and coding scheme (MCS), interfering signal demodulation reference signal (DMRS) ports, and the like.

[0006] Depending on the type of the advanced receiver, not all of the abovementioned parameters may be needed. Parameters belonging to the first category, namely about CRS transmission, may be semi-static in nature and could in principle be exchanged between the eNBs even in case of non-ideal backhaul and X2 interface, as they do not need to be signaled to the UE very often. However, the parameters in the second category, may depend on dynamic scheduling decisions made by the eNB scheduler. The eNB can make scheduling decisions once per 1 ms transmission time interval (TTI), hence exchanging the parameters between the eNBs and signaling to the UE along with the downlink grants from the serving cell may not be feasible in case of non-ideal backhaul and X2 interface. Still, for enabling advanced receiver operation at the NAICS UE without requiring the NAICS UE to blindly detect all the interference parameters, these parameters can be signaled to the NAICS UE in the downlink control information (DCI).

[0007] Dynamic signaling of interfering parameters may be possible from the serving cell or from the interfering cell. The signaling can be also dedicated, broadcast, or it may be appended in legacy DCIs. Dynamic signaling of the interference parameters from the serving eNB can imply that the interfering eNB signals the interfering parameters of interest to the serving eNB using the backhaul link connecting the serving and the interfering eNBs. Exposing the dynamic parameters to the backhaul delay may reduce the interference cancellation efficiency of a NAICS receiver.

[0008] Thus, the NAICS UE may get the NAICS assistance information signaled dynamically directly from the interfering cell. In other words, the NAICS UE may monitor the control channel, such as the physical downlink control channel (PDCCH) or enhanced PDCCH (EPDCCH), transmitted by the interfering cell. The NAICS UE may hence decode the NAICS assistance information directly from the interfering cell. Control channel transmitted from the interfering cell may be highly interfered, because in a synchronous network the control region - at least the PDCCH region - may collide with that of other cells, including the serving cell. Moreover, in a network utilizing NAICS, many or most cells may be continuously broadcasting the NAICS DCI, potentially causing heavy interference on the control channel. Indeed, the NAICS DCIs being transmitted in different cells may conventionally interfere with each other continuously in a persistent manner in all subframes.

[0009] Conventional PDCCH resource mapping does not contain any mechanism for reducing such persistent interference on broadcasted (group-) common DCIs. Conventional PDCCH resource mapping is illustrated in Figure 1.

[0010] In a conventional approach the resource mapping includes the following. First, a symbol quadruplet stream from PDCCH encoding and modulation is fed to an interleaver (N_rows x 32 matrix), row by row. Then, the interleaver columns are permuted. Next, symbol quadruplets are read out from the interleaver matrix column by column. After that, the symbol quadruplet stream is cyclically shifted by cell ID. Finally, the symbol quadruplets are mapped to resource element groups (REGs), which include four resource elements each.

[0011] The only cell-specific randomization of the radio resources on which the symbols are transmitted is the cyclic shifting of the interleaver output. This means that a given search space location will be transmitted exactly on the same resource elements (REs) in every subframe within a given cell. Hence, a NAICS DCI could be, at least partly, colliding continuously with the NAICS DCI transmitted in another cell.

[0012] Issues related to NAICS DCI transmission do not have numerous conventional treatments. One conventional approach involves transmitting NAICS DCI from the interfering cell, but does not resolve issues related to reliability and signal to interference plus noise ratio (SINR) conditions for such transmission. Another potential solution is to apply NAICS DCI cancelation at the UE, however this would require the perfect alignment of the NAICS DCI of neighbor eNBs.

SUMMARY:

[0013] According to certain embodiments, a method can include transmitting, to a user equipment, parameters comprising a cell identifier of a cell transmitting network aided interference cancellation and suppression downlink control information. The method can also include transmitting downlink control information consistent with the parameters.

[0014] In a variant, the parameters further include at least one of a number of transmit antennas, physical hybrid automatic repeat request indicator channel duration, number of physical hybrid automatic repeat request indicator channel groups, or control format indicator.

[0015] In a variant, the parameters further include at least one of a fixed offset indicating a starting position for a downlink control channel search space location or a parameter from which a search space hopping pattern is derivable.

[0016] In a variant, an amount of parameters transmitted depends on whether the cell is a serving cell or an interfering cell with respect to the user equipment.

[0017] In a variant, the parameters include at least one of type of enhanced physical downlink control channel; resource block assignment; enhanced physical downlink control channel starting symbol; demodulation reference signal scrambling sequence; and resource element mapping and quasi-colocation information.

[0018] In a variant, the method includes receiving information regarding a neighbor base station regarding downlink control information for the neighbor base station.

[0019] In a variant, the information includes parameters related to a downlink control channel and search space.

[0020] In a variant, the method further includes sending the information regarding the neighbor base station to the user equipment.

[0021] In a variant, the method further includes determining search space parameters for an own base station based on the information.

[0022] In a variant, the method includes receiving information regarding a neighbor base station regarding a downlink control information search space for the neighbor base station.

[0023] In certain embodiments, a method can include receiving, at a user equipment, parameters comprising a cell identifier of a cell transmitting network aided interference cancellation and suppression downlink control information. The method can also include searching for downlink control information based on the parameters. [0024] In a variant, the parameters further include at least one of a number of transmit antennas, physical hybrid automatic repeat request indicator channel duration, number of physical hybrid automatic repeat request indicator channel groups, or control format indicator.

[0025] In a variant, the searching can include deriving a physical downlink control channel search space location for the downlink control information based on the parameters.

[0026] In a variant, the parameters further include at least one of a fixed offset indicating a starting position for a downlink control channel search space location or a parameter from which a search space hopping pattern is derivable.

[0027] In a variant, the parameters include at least one of type of enhanced physical downlink control channel; resource block assignment; enhanced physical downlink control channel starting symbol; demodulation reference signal scrambling sequence; and resource element mapping and quasi-colocation information and transmit power indication in the form of one or more power offset values.

[0028] Apparatuses, in certain embodiments, can include means for performing the above described methods in all or any of their variants.

[0029] Apparatuses, in certain embodiments, can include at least one processor and at least one memory including computer program code. The at least one memory and the computer program code can be configured to, with at least one processor, cause the apparatuses at least to perform the methods described above in any or all of their variants.

[0030] A non-transitory computer readable medium can be encoded with instructions that, when executed in hardware, perform a process. The process can include the methods described above in any or all of their variants.

[0031] A computer program product can encode instructions for performing a process. The process can include the methods described above in any or all of their variants. BRIEF DESCRIPTION OF THE DRAWINGS:

[0032] For proper understanding of the invention, reference should be made to the accompanying drawings, wherein:

[0033] Figure 1 illustrates conventional PDCCH resource mapping.

[0034] Figure 2 illustrates a method according to certain embodiments.

[0035] Figure 3 illustrates another method according to certain embodiments.

[0036] Figure 4 illustrates a system according to certain embodiments.

DETAILED DESCRIPTION:

[0037] Certain embodiments may provide for improved reception of the NAICS DCI. Likewise, certain embodiments may improve reception SINR of the NAICS DCI. Different aspects of certain embodiments variously address these and other issues. It may be impossible to avoid interference completely on the PDCCH control channel due to how the resource mapping is specified, and the fact that the resource mapping can also depend on various parameters, such as the number of CRS ports and physical hybrid automatic repeat request (ARQ) indicator channel (PHICH) configuration. In low control channel load situations, for example in small cells, it may be possible to reduce interference. In particular, certain embodiments can minimize the persistent interference caused by NAICS DCI transmission in one cell to NAICS DCI transmission in another cell. Such interference may represent a significant fraction of all control traffic in some cases.

[0038] As described above, generally the UE may need to be informed about interference characteristics for proper interference suppression/cancellation. Moreover, for best UE detection complexity reduction, dynamic parameters can be signaled. This signaling can occur via, for example, PDCCH or EPDCCH. Moreover, in NAICS scenarios, the nodes are not necessarily connected by an ideal backhaul that would enable dynamic signaling of interference characteristics from the serving cell. Instead, the DCI may need to come from the interfering cell itself in the case of non-ideal backhaul. Furthermore, with respect to dynamic parameters, the NAICS DCI may need to be transmitted in practically every subframe, when NAICS UEs are being scheduled.

[0039] Hence, the NAICS DCI from the serving cell might interfere with the desired NAICS DCI from the interfering cell. Such interference can lead to bad SINR conditions, particularly on PDCCH where, due to resource mapping, NAICS DCI transmissions from two cells may collide continuously in the same way.

[0040] Accordingly, as indicated above, certain embodiments can ensure reliable reception of NAICS DCI and enhance the reception SINR of NAICS DCI.

[0041] According to a first approach, certain embodiments can permit semi-static configuration of the NAICS signaling cell. In some cases, depending on the deployment, ideal backhaul may be available. In such cases the signaling could come from the serving cell. In other cases, only non-ideal backhaul is available. In such cases the signaling can come from the interfering cell.

[0042] Hence, the UE can be signaled parameters about the cell transmitting the NAICS DCI. The parameters can include at least cell identifier (ID). If the cell ID does not correspond to serving cell, the parameters can further include the following: number of transmit (Tx) antennas, PHICH duration, number of PHICH groups, and possibly control format indicator (CFI), unless blindly detected. These parameters can be used for PDCCH resource mapping

[0043] According to a second approach, certain embodiments can involve interference randomization. According to a conventional PDCCH resource mapping, the only cell-specific randomization is as follows. The conventional approach include a symbol quadruplet stream from PDCCH encoding and modulation being fed to an interleaver (N_rows x 32 matrix), row by row. The conventional approach can also include the interleaver columns being permuted and then symbol quadruplets being read from the interleaver matrix column by column. Finally, the symbol quadruplet stream can be cyclically shifted by cell ID in the conventional PDCCH resource mapping. The symbol quadruplets can be mapped to REGs.

[0044] In view of the fact that the only randomization currently is the cell ID- specific cyclic shift, the NAICS DCI between two cells may collide continuously in the same way, at least if transmitted in the same search space location. Even partial collision would decrease the NAICS DCI reception reliability.

[0045] By contrast, certain embodiments can enable a configurable start location for NAICS search space. The start location can be determined such that collisions between NAICS DCIs are minimized. The start location can be determined also such that collision between NAICS DCIs leads to an overlap which would facilitate NAICS DCI cancellation by the NAICS UEs. Furthermore, certain embodiments may enable search space hopping, minimizing persistent collisions. For example, there can be additional randomization of the search space location based on NAICS radio network temporary identifier (RNTI).

[0046] To map NAICS DCI on neighboring cell EPDCCH, the UE may need to be aware of the resource mapping in neighboring cell. Thus, CRS, CSI-RS, and EPDCCH starting position may be provided to the UE.

[0047] Also, EPDCCH physical resource blocks (PRBs) and other EPDCCH parameters may need to be configured. This can be part of the NAICS DCI originating cell configuration. EPDCCH resources can be coordinated. For example, orthogonalization may be possible. In such a case, there may be no need for further randomization.

[0048] More generally, certain embodiments provide methods for improving the NAICS DCI reception conditions in situations where different cells are broadcasting any kind of NAICS DCI containing information about the interference generated by that cell. In general, an eNB can configure NAICS UE parameters indicating the radio resources used to transmit the NAICS DCI. This may permit the eNB to determine such resources where the interference could be minimized.

[0049] Certain embodiments can involve configuring the NAICS UE to receive NAICS DCI from a certain cell, on PDCCH or EPDCCH, including configuration of the relevant parameters to enable NAICS DCI reception from that cell. The provision of these parameters can be by transmission of the NAICS DCI from the serving cell instead of interfering cell, when ideal backhaul is in fact available. This may avoid bad reception conditions, but may be limited to cases of ideal backhaul, as broadly described above. On the other hand, depending on interference conditions, different neighboring cells can be configured as the NAICS DCI originating cell for the NAICS UE.

[0050] In another aspect of certain embodiments, the NAICS UE can be configured with parameters that are used to derive a PDCCH search space location for the NAICS DCI. These parameters can include a fixed offset indicating the starting position and/or a parameter used to derive a search space hopping pattern. The provision of such parameters can facilitate randomization of interference as well as minimization of colliding REs for NAICS DCI transmission between the cells. On the other hand, the provision of such parameters can facilitate persistent collision of the NAICS DCI which would facilitate the cancelation by the NAICS UE of the interfering NAICS DCIs.

[0051] EPDCCH may support orthogonalization of control signaling between two cells. Thus, there may be no similar need for further optimization in that case.

[0052] Certain embodiments may relate to the utilization of the same or different types of NAICS DCI, if the dynamic signaling happens from the interfering or the serving cell. In one instance, the same NAICS DCI information can be transmitted from either interfering or the serving cell. In another instance, different NAICS DCI can be transmitted. For example, fewer interference parameters can be transmitted in a NAICS DCI sent from the interfering cell. Such an approach may be used in, for example, a non-ideal backhaul scenario. For example, the parameters can indicate the transmission scheme, rank 1 information, or the like. On the other hand, more information can be transmitted in a NAICS DCI originating from the serving cell, this being understood as an ideal backhaul case. For example more than rank 1 information, or the like, can be provided. [0053] In more detail, according to certain embodiments, the serving eNB can configure, via radio resource control (RRC), to the NAICS UE, parameters according to which the NAICS UE may receive the NAICS DCI from a certain cell. These parameters can include, in the case of PDCCH, the following: cell ID for the cell from which the NAICS DCI is to originate; and a number of CRS ports, PHICH duration, number of PHICH groups (N_g in TS 36.211), and possibly CFI, unless required to be blindly detected by the NAICS UE. These parameters may be used for PDCCH resource mapping.

[0054] In case of EPDCCH, these parameters can include a subset of parameters included in the EPDCCH-Config information element (TS 36.331), at least the following parameters may be used: type of EPDCCH, either localized or distributed, while in an alternative the type of EPDCCH could always be distributed for NAICS DCI; resource block assignment; EPDCCH starting symbol; DMRS scrambling sequence; and RE mapping and quasi-colocation (QCL) information.

[0055] If serving cell is the transmitting cell, the UE may only need to be provided with the information about the EPDCCH set index used for NAICS DCI, assuming that the UE is otherwise configured with EPDCCH and hence is already configured with other parameters. Additionally, the NAICS UE can be configured as to whether PDCCH or EPDCCH is to be used for NAICS DCI reception.

[0056] According another aspect of certain embodiments, the serving eNB can configure, via RRC to the NAICS UE, parameters according to which the NAICS UE can derive the PDCCH search space location(s) from which to try to decode the NAICS DCI. Search space location can refer to certain control channel elements that are mapped to the resource elements as described above. This parameter can be at least one of the following.

[0057] For example, the parameter can be a configurable offset, such as a starting location for the NAICS DCI search space. This can be used to set NAICS DCI search spaces such that the resulting overlap between them is minimized or even completely avoided in some cases. Such a result can be achieved when the interleaving and the cyclic shift used in the PDCCH resource mapping is taken into account. In this case, the NAICS DCI search space location for PDCCH candidate m can be expressed, for example, as

^L { _A ^/ J }+ '^' , i=0,... ,L- l

where n_offset is the configured offset, L={1,2,4,8} is the aggregation level, and Ncc_E._k is the number of CCEs in subframe k.

[0058] For another example, the parameter can be a configurable hopping parameter, which can be used to vary the NAICS DCI search space location in each subframe. Using such a hopping parameter, the possible persistent collisions between NAICS DCIs of different cells can be minimized, as the search space locations may vary all the time. In this case, the search space location for candidate m can, for example, be expressed as

^L { (f(ⁿho_P , k) + m) mod LNcc_E,_t }+ i

where f(n_hop,k) is a function of the configurable hopping parameter and the subframe index k, which varies the search space locations across subframes. As non-limiting examples, the hopping function can be

f(ⁿho_{P >} k) = n_hopk

or a similar way can be follows as for UE-specific PDCCH search space, such that

f(n_hop , k) = (A - f(n_hop , k - l)) mod D

where A and D are prime numbers and

/ „_p -!) = ·

[0059] One possibility for setting the hopping parameter is to set it equal to the NAICS RNTI used to scramble the cyclic redundancy code (CRC) of the NAICS DCIs.

[0060] The eNBs transmitting NAICS DCIs may need to coordinate the parameters over the X2 interface, including the parameters regarding NAICS DCI transmission, as well as the parameters related to the search space, such as the offset and the hopping parameters.

[0061] Figure 2 illustrates a method according to certain embodiments. The method illustrated in Figure 2 may be performed by, for example, one or more base station, such as an eNB. As shown in Figure 2, at 210, the method can include the interfering eNB, based for example on the load indicator and hence in high load conditions, informing neighbor eNBs of the intention of transmitting the NAICS DCI control channel. The neighbor eNBs can include, among others, the serving eNB of a particular NAICS UE that will be mentioned below. The interfering eNB may also indicate the parameters related to PDCCH/EPDCCH and search space to the other eNB. This transmission between eNBs may be optional and may not be included in certain embodiments.

[0062] The method can also include, at 220, the serving eNB determining search space related parameters, such as offset/starting point and hopping parameter, such that the interference on the NAICS DCI can be minimized.

[0063] Further, the method can include, at 230, the serving eNB configuring, via RRC, parameters to the NAICS UE according to which the NAICS UE may receive the NAICS DCI from a certain cell, or from more than one cell. Such parameters may include, in case of PDCCH, but are not limited to the following: cell ID of the originating NAICS DCI, number of CRS ports, PHICH duration, number of PHICH groups (N_g), and possibly CFI. In case of EPDCCH, such parameters may include a subset of EPDCCH parameters as discussed above.

[0064] At 240, the method can include the serving eNB configuring, via RRC, parameters to the NAICS UE according to which the NAICS UE shall derive the PDCCH search space location(s) from which to try to decode the NAICS DCI. The serving eNB may configure a starting location for the NAICS DCI search space, in the form of indicating an offset. Also or alternatively, the serving eNB may configure a hopping parameter. [0065] At 250, the method can include the interfering eNB sending to the neighbor eNBs, over the X2 interface, parameters used for the NAICS DCI search space configuration. Such parameters may include at least some of the following: an offset which can be used as the starting location for the NAICS DCI search space; and/or a hopping parameter which can be used to vary the NAICS DCI search space location in each subframe. This transmission between eNBs may be optional and may not be included in certain embodiments.

[0066] Figure 3 illustrates another method according to certain embodiments. The method may be performed by a device such as a user equipment. As shown in Figure 3, the method can include, at 310, the UE receiving from the serving cell, via RRC, the parameters indicating the NAICS DCI originating cell, and the parameters used to receive PDCCH/EPDCCH from that cell. In case of PDCCH, the UE may receive the following parameters, but not limited to: cell ID of the originating NAICS DCI, number of CRS ports, PHICH duration, number of PHICH groups (N_g), and possibly CFI. In case of EPDCCH, the UE may receive a subset of the EPDCCH-related parameters as discussed above. In case the UE receives NAICS DCI from the serving cell, the UE can implicitly differentiate between a NAICS DCI transmitted from the interfering cell and a NAICS DCI transmitted from a serving cell. In case multiple NAICS DCIs collide with each other as a results of an intentional configuration by the transmitting eNBs, the NAICS UE may have the ability to cancel the interfering NAICS DCIs.

[0067] At 320, if PDCCH is used, the UE can receive from the serving cell, either on RRC or on regular DCI, the parameters which can be used to derive the PDCCH search space transmitted from the interfering cell in order to decode the NAICS DCI. For example, the UE may receive an offset which is used as the starting location for the NAICS DCI search space. Also, or in addition, the UE may receive a hopping parameter which is used to vary the NAICS DCI search space location in each subframe. Then, at 330, the method can including search for downlink control information based on the parameters.

[0068] Figure 4 illustrates a system according to certain embodiments. It should be understood that each block of the flowchart of Figures 2 or 3 and any combination thereof may be implemented by various means or their combinations, such as hardware, software, firmware, one or more processors and/or circuitry. In one embodiment, a system may include several devices, such as, for example, network element 410 and user equipment (UE) or user device 420. The system may include more than one UE 420 and more than one network element 410, although only one of each is shown for the purposes of illustration. A network element can be an access point, a base station, an eNode B (eNB), server, host or any of the other network elements discussed herein. Each of these devices may include at least one processor or control unit or module, respectively indicated as 414 and 424. At least one memory may be provided in each device, and indicated as 415 and 425, respectively. The memory may include computer program instructions or computer code contained therein. One or more transceiver 416 and 426 may be provided, and each device may also include an antenna, respectively illustrated as 417 and 427. Although only one antenna each is shown, many antennas and multiple antenna elements may be provided to each of the devices. Other configurations of these devices, for example, may be provided. For example, network element 410 and UE 420 may be additionally configured for wired communication, in addition to wireless communication, and in such a case antennas 417 and 427 may illustrate any form of communication hardware, without being limited to merely an antenna. Likewise, some network elements 410 may be solely configured for wired communication, and in such cases antenna 417 may illustrate any form of wired communication hardware, such as a network interface card.

[0069] Transceivers 416 and 426 may each, independently, be a transmitter, a receiver, or both a transmitter and a receiver, or a unit or device that may be configured both for transmission and reception. The transmitter and/or receiver (as far as radio parts are concerned) may also be implemented as a remote radio head which is not located in the device itself, but in a mast, for example. The operations and functionalities may be performed in different entities, such as nodes, hosts or servers, in a flexible manner. In other words, division of labor may vary case by case. One possible use is to make a network element deliver local content. One or more functionalities may also be implemented as virtual application(s) in software that can run on a server.

[0070] A user device or user equipment 420 may be a mobile station (MS) such as a mobile phone or smart phone or multimedia device, a computer, such as a tablet, provided with wireless communication capabilities, personal data or digital assistant (PDA) provided with wireless communication capabilities, portable media player, digital camera, pocket video camera, navigation unit provided with wireless communication capabilities or any combinations thereof.

[0071] In an exemplary embodiment, an apparatus, such as a node or user device, may include means for carrying out embodiments described above in relation to Figures 2 or 3.

[0072] Processors 414 and 424 may be embodied by any computational or data processing device, such as a central processing unit (CPU), digital signal processor (DSP), application specific integrated circuit (ASIC), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), digitally enhanced circuits, or comparable device or a combination thereof. The processors may be implemented as a single controller, or a plurality of controllers or processors.

[0073] For firmware or software, the implementation may include modules or unit of at least one chip set (for example, procedures, functions, and so on). Memories 415 and 425 may independently be any suitable storage device, such as a non- transitory computer-readable medium. A hard disk drive (HDD), random access memory (RAM), flash memory, or other suitable memory may be used. The memories may be combined on a single integrated circuit as the processor, or may be separate therefrom. Furthermore, the computer program instructions may be stored in the memory and which may be processed by the processors can be any suitable form of computer program code, for example, a compiled or interpreted computer program written in any suitable programming language. The memory or data storage entity is typically internal but may also be external or a combination thereof, such as in the case when additional memory capacity is obtained from a service provider. The memory may be fixed or removable.

[0074] The memory and the computer program instructions may be configured, with the processor for the particular device, to cause a hardware apparatus such as network element 410 and/or UE 420, to perform any of the processes described above (see, for example, Figures 2 and 3). Therefore, in certain embodiments, a non-transitory computer-readable medium may be encoded with computer instructions or one or more computer program (such as added or updated software routine, applet or macro) that, when executed in hardware, may perform a process such as one of the processes described herein. Computer programs may be coded by a programming language, which may be a high-level programming language, such as objective-C, C, C++, C#, Java, etc., or a low- level programming language, such as a machine language, or assembler. Alternatively, certain embodiments of the invention may be performed entirely in hardware.

[0075] Furthermore, although Figure 4 illustrates a system including a network element 410 and a UE 420, embodiments of the invention may be applicable to other configurations, and configurations involving additional elements, as illustrated and discussed herein. For example, multiple user equipment devices and multiple network elements may be present, or other nodes providing similar functionality, such as nodes that combine the functionality of a user equipment and an access point, such as a relay node. The UE 420 may likewise be provided with a variety of configurations for communication other than communication network element 410. For example, the UE 420 may be configured for device- to-device communication.

[0076] Certain embodiments may have various benefits or advantages. For example, certain embodiments can be used to improve NAICS DCI reception conditions. More particularly, certain embodiments can be used to reduce persistent collisions between NAICS DCIs transmitted in different cells.

[0077] One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention.

[0078] Partial Glossary

[0079] 3GPP Third Generation Partnership Program

[0080] CFI Control Format Indicator

[0081] C-RNTI Cell RNTI

[0082] DCI Downlink Control Information

[0083] DL Downlink

[0084] DMRS Demodulation Reference Signal

[0085] eNB eNode B (Base Station)

[0086] FDD Frequency Division Duplexing

[0087] HARQ Hybrid Automatic Repeat Request

[0088] LTE Long Term Evolution

[0089] MU-MIMO Multi User Multi Input Multiple Output

[0090] NAICS Network Assisted Interference <

Suppression

[0091] PBCH Physical Broadcast Channel

[0092] PCI Physical Cell ID

[0093] PDCCH Physical Downlink Control Channel

[0094] PDSCH Physical Downlink Shared Channel

[0095] PHICH Physical Hybrid- ARQ Indicator Channel

[0096] PHY Physical (layer)

[0097] QCL Quasi-Colocation [0098] RAN Radio Access Network

[0099] RE Resource Element

[0100] Rel Release

[0101] RNTI Radio Network Temporary Identifier

[0102] RRM Radio Resource Management

[0103] SINR Signal-to-Interference and Noise Ratio

[0104] SU-MIMO Single User Multi Input Multiple Output

[0105] UE User Equipment

[0106] UL, U Uplink

[0107] X2 Logical interface between network elements.

Claims

WE CLAIM:

1. A method, comprising:

transmitting, to a user equipment, parameters comprising a cell identifier of a cell transmitting network aided interference cancellation and suppression downlink control information; and

transmitting downlink control information consistent with the parameters.

2. The method of claim 1, wherein the parameters further comprise at least one of a number of transmit antennas, physical hybrid automatic repeat request indicator channel duration, number of physical hybrid automatic repeat request indicator channel groups, or control format indicator.

3. The method of claim 1, wherein the parameters further comprise at least one of a fixed offset indicating a starting position for a downlink control channel search space location or a parameter from which a search space hopping pattern is derivable.

4. The method of claim 1, wherein an amount of parameters transmitted depends on whether the cell is a serving cell or an interfering cell with respect to the user equipment.

5. The method of claim 1, wherein the parameters comprise at least one of type of enhanced physical downlink control channel;

type of physical downlink control channel;

resource block assignment;

enhanced physical downlink control channel starting symbol;

physical downlink control channel starting symbol;

demodulation reference signal scrambling sequence; or

resource element mapping and quasi-colocation information.

6. The method of claim 1, further comprising:

receiving information regarding a neighbor base station regarding downlink control information for the neighbor base station.

7. The method of claim 6, wherein the information comprises parameters related to a downlink control channel and search space.

8. The method of claim 6, further comprising:

sending the information regarding the neighbor base station to the user equipment.

9. The method of claim 6, further comprising:

determining search space parameters for an own base station based on the information.

10. The method of claim 1, further comprising:

receiving information regarding a neighbor base station regarding a downlink control information search space for the neighbor base station.

11. A method, comprising:

receiving, at a user equipment, parameters comprising a cell identifier of a cell transmitting network aided interference cancellation and suppression downlink control information; and

searching for downlink control information based on the parameters.

12. The method of claim 11, wherein the parameters further comprise at least one of a number of transmit antennas, physical hybrid automatic repeat request indicator channel duration, number of physical hybrid automatic repeat request indicator channel groups, or control format indicator.

13. The method of claim 11, wherein the searching comprises deriving a physical downlink control channel search space location for the downlink control information based on the parameters.

14. The method of claim 11, wherein the parameters further comprise at least one of a fixed offset indicating a starting position for a downlink control channel search space location or a parameter from which a search space hopping pattern is derivable.

15. The method of claim 11, wherein the parameters comprise at least one of

type of enhanced physical downlink control channel;

type of physical downlink control channel;

resource block assignment;

enhanced physical downlink control channel starting symbol;

physical downlink control channel starting symbol;

demodulation reference signal scrambling sequence; or

resource element mapping and quasi-colocation information.

16. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to

transmit, to a user equipment, parameters comprising a cell identifier of a cell transmitting network aided interference cancellation and suppression downlink control information; and

transmit downlink control information consistent with the parameters.

17. The apparatus of claim 16, wherein the parameters further comprise at least one of a number of transmit antennas, physical hybrid automatic repeat request indicator channel duration, number of physical hybrid automatic repeat request indicator channel groups, or control format indicator.

18. The apparatus of claim 16, wherein the parameters further comprise at least one of a fixed offset indicating a starting position for a downlink control channel search space location or a parameter from which a search space hopping pattern is derivable.

19. The apparatus of claim 16, wherein an amount of parameters transmitted depends on whether the cell is a serving cell or an interfering cell with respect to the user equipment.

20. The apparatus of claim 16, wherein the parameters comprise at least one of

type of enhanced physical downlink control channel;

type of physical downlink control channel;

resource block assignment;

enhanced physical downlink control channel starting symbol;

physical downlink control channel starting symbol;

demodulation reference signal scrambling sequence; or

resource element mapping and quasi-colocation information.

21. The apparatus of claim 16, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to receive information regarding a neighbor base station regarding downlink control information for the neighbor base station.

22. The apparatus of claim 21, wherein the information comprises parameters related to a downlink control channel and search space.

23. The apparatus of claim 21, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to send the information regarding the neighbor base station to the user equipment.

24. The apparatus of claim 21, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to determine search space parameters for an own base station based on the information.

25. The apparatus of claim 16, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to receive information regarding a neighbor base station regarding a downlink control information search space for the neighbor base station.

26. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to

receive, at a user equipment, parameters comprising a cell identifier of a cell transmitting network aided interference cancellation and suppression downlink control information; and

search for downlink control information based on the parameters.

27. The apparatus of claim 26, wherein the parameters further comprise at least one of a number of transmit antennas, physical hybrid automatic repeat request indicator channel duration, number of physical hybrid automatic repeat request indicator channel groups, or control format indicator.

28. The apparatus of claim 26, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to search at least by deriving a physical downlink control channel search space location for the downlink control information based on the parameters.

29. The apparatus of claim 26, wherein the parameters further comprise at least one of a fixed offset indicating a starting position for a downlink control channel search space location or a parameter from which a search space hopping pattern is derivable.

30. The apparatus of claim 26, wherein the parameters comprise at least one of

type of enhanced physical downlink control channel;

type of physical downlink control channel;

resource block assignment;

enhanced physical downlink control channel starting symbol;

physical downlink control channel starting symbol;

demodulation reference signal scrambling sequence; or

resource element mapping and quasi-colocation information.

31. An apparatus, comprising:

means for transmitting, to a user equipment, parameters comprising a cell identifier of a cell transmitting network aided interference cancellation and suppression downlink control information; and

means for transmitting downlink control information consistent with the parameters.

32. The apparatus of claim 31, wherein the parameters further comprise at least one of a number of transmit antennas, physical hybrid automatic repeat request indicator channel duration, number of physical hybrid automatic repeat request indicator channel groups, or control format indicator.

33. The apparatus of claim 31, wherein the parameters further comprise at least one of a fixed offset indicating a starting position for a downlink control channel search space location or a parameter from which a search space hopping pattern is derivable.

34. The apparatus of claim 31, wherein an amount of parameters transmitted depends on whether the cell is a serving cell or an interfering cell with respect to the user equipment.

35. The apparatus of claim 31, wherein the parameters comprise at least one of

type of enhanced physical downlink control channel;

type of physical downlink control channel;

resource block assignment;

enhanced physical downlink control channel starting symbol;

physical downlink control channel starting symbol;

demodulation reference signal scrambling sequence; or

resource element mapping and quasi-colocation information.

36. The apparatus of claim 31, further comprising:

means for receiving information regarding a neighbor base station regarding downlink control information for the neighbor base station.

37. The apparatus of claim 36, wherein the information comprises parameters related to a downlink control channel and search space.

38. The apparatus of claim 36, further comprising:

means for sending the information regarding the neighbor base station to the user equipment.

39. The apparatus of claim 36, further comprising:

means for determining search space parameters for an own base station based on the information.

40. The apparatus of claim 31, further comprising:

means for receiving information regarding a neighbor base station regarding a downlink control information search space for the neighbor base station.

41. An apparatus, comprising:

means for receiving, at a user equipment, parameters comprising a cell identifier of a cell transmitting network aided interference cancellation and suppression downlink control information; and

means for searching for downlink control information based on the parameters.

42. The apparatus of claim 41, wherein the parameters further comprise at least one of a number of transmit antennas, physical hybrid automatic repeat request indicator channel duration, number of physical hybrid automatic repeat request indicator channel groups, or control format indicator.

43. The apparatus of claim 41, wherein the searching comprises deriving a physical downlink control channel search space location for the downlink control information based on the parameters.

44. The apparatus of claim 41, wherein the parameters further comprise at least one of a fixed offset indicating a starting position for a downlink control channel search space location or a parameter from which a search space hopping pattern is derivable.

45. The apparatus of claim 41, wherein the parameters comprise at least one of

type of enhanced physical downlink control channel;

type of physical downlink control channel;

resource block assignment;

enhanced physical downlink control channel starting symbol;

physical downlink control channel starting symbol;

demodulation reference signal scrambling sequence; or

resource element mapping and quasi-colocation information.

46. A computer program product encoding instructions for performing a process, the process comprising the method according to any of claims 1-15.

47. A non-transitory computer-readable medium encoded with instructions that, when executed in hardware, perform a process, the process comprising the method according to any of claims 1-15.

48. A system, comprising:

a first apparatus, comprising an apparatus according to any of claims 16-25 or 31-40; and

a second apparatus, comprising an apparatus according to any of claims 26- 30 or 41-45,

wherein the first apparatus and second apparatus are operationally and communicatively interconnected.