Selecting a cell identifier based on a downlink control information

A method, an apparatus, and a computer program product for wireless communication are provided in which a cell identifier is selected based on one or more properties associated with received downlink control information (DCI), where the properties may not be exclusively associated with determining a cell identifier. The cell identifier may be selected from a plurality of cell identifiers received through radio resource control signaling. The properties of the DCI may include a type of download control channel, a type of subframe and a type of DCI format used to provide the DCI.

BACKGROUND

Field

The present disclosure relates generally to communication systems, and more particularly, to wireless communication systems may employ virtual cell identifiers.

Background

SUMMARY

Certain embodiments of the invention provide a method of communicating configuration information in a wireless communication system. In particular, a set of static or semi-static configuration parameters may be provided to user equipment. The user equipment may then select specific parameters based on signaling received during subsequent operation. The selection of specific parameters may be based on a signaled index value and may also be based on information derived from the format of downlink control information received by the user equipment.

The disclosed systems and methods enable the identification of virtual cell identifiers to be used by the user equipment and may also identify the methods by which the user equipment can communicate feedback and flow control information to a base station.

In an aspect of the disclosure, a method of wireless communications comprises receiving a signal including downlink control information (DCI), and selecting one of a plurality of cell identifiers based on one or more properties associated with the DCI. The one or more properties may not be exclusively associated with determining a cell identifier. The method may also include initializing a pseudo-random sequence generator based on the selected cell identifier. In an aspect of the disclosure, the method comprises receiving the plurality of cell identifiers via radio resource control (RRC) signaling.

In certain embodiments, the DCI is received in an enhanced physical download control channel (ePDCCH). The ePDCCH may be scrambled with an ePDCCH scrambling identifier. In some embodiments, the cell identifier may be selected by determining a type of format of the DCI, and selecting the selected cell identifier based on the ePDCCH scrambling identifier when the DCI has a type 1A format. In some embodiments, the cell identifier may be selected by determining a type of format of the DCI, and selecting a predetermined cell identifier when the DCI has a type 1A format.

In an aspect of the disclosure, the cell identifier may be selected by determining a subframe type in which the DCI is received, and determining whether the subframe is a Multi-Media Broadcast over a Single Frequency Network (MBSFN) subframe or a non-MBSFN subframe. The cell identifier may be selected, at least in part, based on the subframe type.

In an aspect of the disclosure, receiving a signal includes receiving the DCI in a first set of candidate control channels (CCEs) of at least two sets of CCEs, and the selected cell identifier is selected, at least in part, based on the set of CCEs in which the DCI is received. In some embodiments, the DCI includes an uplink grant, and the selected cell identifier is used for an uplink transmission corresponding to the uplink grant.

In an aspect of the disclosure, the method comprises providing channel state information (CSI) based on the selected cell identifier.

In an aspect of the disclosure, a method of wireless communications comprises receiving a signal including downlink control information (DCI) including an uplink grant, identifying a physical hybrid ARQ indicator channel (PHICH) in a control region when the grant is provided in a PDCCH, and identifying an enhanced PHICH in a data region when the grant is provided in a ePDCCH.

In an aspect of the disclosure, the method comprises selecting one of a plurality of cell identifiers based on a property associated with the DCI. The property may not exclusively related to determining a cell identifier.

In an aspect of the disclosure, the method comprises providing an acknowledgement or a negative acknowledgement based on the selected cell identifier.

In an aspect of the disclosure, a method of wireless communications comprises determining an index based on a format type of DCI, and selecting a set of parameters from a plurality of sets of the parameters based on the index. The set of parameters may define one or more characteristics of a virtual cell, and the plurality of sets of the parameters is configured through RRC signaling.

In an aspect of the disclosure, a method of wireless communications comprises initializing a pseudo-random sequence generator using one parameter of the selected set of parameters. The set of parameters may be used to define characteristics of an uplink communication channel.

DETAILED DESCRIPTION

The E-UTRAN includes the evolved Node B (eNB)106and other eNBs108. The eNB106provides user and control planes protocol terminations toward the UE102. The eNB106may be connected to the other eNBs108via an X2 interface (e.g., backhaul). The eNB106may also be referred to as a base station, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), or some other suitable terminology. The eNB106provides an access point to the EPC110for a UE102. Examples of UEs102include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device. The UE102may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

The eNB106is connected by an S1 interface to the EPC110. The EPC110includes a Mobility Management Entity (MME)112, other MMEs114, a Serving Gateway116, and a Packet Data Network (PDN) Gateway118. The MME112is the control node that processes the signaling between the UE102and the EPC110. Generally, the MME112provides bearer and connection management. All user IP packets are transferred through the Serving Gateway116, which itself is connected to the PDN Gateway118. The PDN Gateway118provides UE IP address allocation as well as other functions. The PDN Gateway118is connected to the Operator's IP Services122. The Operator's IP Services122may include the Internet, the Intranet, an IP Multimedia Subsystem (IMS), and a PS Streaming Service (PSS).

FIG. 2is a diagram illustrating an example of an access network200in an LTE network architecture. In this example, the access network200is divided into a number of cellular regions (cells)202. One or more lower power class eNBs208may have cellular regions210that overlap with one or more of the cells202. The lower power class eNB208may be a femto cell (e.g., home eNB (HeNB)), pico cell, micro cell, or remote radio head (RRH). The macro eNBs204are each assigned to a respective cell202and are configured to provide an access point to the EPC110for all the UEs206in the cells202. There is no centralized controller in this example of an access network200, but a centralized controller may be used in alternative configurations. The eNBs204are responsible for all radio related functions including radio bearer control, admission control, mobility control, scheduling, security, and connectivity to the serving gateway116.

FIG. 7is a diagram750illustrating evolved Multicast Broadcast Multimedia Service (eMBMS) in a Multi-Media Broadcast over a Single Frequency Network (MBSFN). The eNBs752in cells752′ may form a first MBSFN area and the eNBs754in cells754′ may form a second MBSFN area. The eNBs752,754may be associated with other MBSFN areas, for example, up to a total of eight MBSFN areas. A cell within an MBSFN area may be designated a reserved cell. Reserved cells do not provide multicast/broadcast content, but are time-synchronized to the cells752′,754′ and have restricted power on MBSFN resources in order to limit interference to the MBSFN areas. Each eNB in an MBSFN area synchronously transmits the same eMBMS control information and data. Each area may support broadcast, multicast, and unicast services. A unicast service is a service intended for a specific user, e.g., a voice call. A multicast service is a service that may be received by a group of users, e.g., a subscription video service. A broadcast service is a service that may be received by all users, e.g., a news broadcast. Referring toFIG. 7, the first MBSFN area may support a first eMBMS broadcast service, such as by providing a particular news broadcast to UE770. The second MBSFN area may support a second eMBMS broadcast service, such as by providing a different news broadcast to UE760. Each MBSFN area supports a plurality of physical multicast channels (PMCH) (e.g., 15 PMCHs). Each PMCH corresponds to a multicast channel (MCH). Each MCH can multiplex a plurality (e.g., 29) of multicast logical channels. Each MBSFN area may have one multicast control channel (MCCH). As such, one MCH may multiplex one MCCH and a plurality of multicast traffic channels (MTCHs) and the remaining MCHs may multiplex a plurality of MTCHs.

FIG. 8is a diagram800illustrating a method of configuring a UE802. An eNB804may signal, through transmitter806, certain information, such as one or more virtual cell identifiers808, to the UE802using RRC sublayer810. Dynamic signaling may then be used to cause UE802to select one of virtual cell identifiers808, or another cell identifier such as a predetermined and/or physical cell identifier. In some embodiments, the dynamic signaling provides an index that can be used to configure an aspect of UE802operation by selecting the cell identifier. In some embodiments, a dynamically signaled index may be used to access a set of statically or semi-statically defined parameters in the UE802that may configure individual operational aspects of a virtual cell.

Certain channels used for wireless communications may be scrambled using a scrambling sequence generator that is initialized using a cell identifier. For example, a demodulation reference signal (DM-RS) pseudo-random sequence generator may be initialized at the beginning of each subframe using a cell identifier NIDcellusing:
cinit=(└ns/2┘+1)·(2NIDcell+1)·216+nSCID,
where nSrepresents slot number, NIDcell, is the cell identifier for the serving cell and nSCIDis a scrambling sequence number configured by the base station, which is dynamically conveyed to the UE802, typically in DCI associated with a PDSCH transmission. The initialization value may be determined using a different function when virtual cell identifiers are used. For example, a pseudo random sequence generator may be initialized using a value cinit, where:
cinit=(└ns/2┘+1)·(2X+1)·216+nSCID.
X is may be referred to as a virtual cell identifier, and may be a dynamically selected parameter.

Dynamic signaling may be used to select a virtual cell identifier X from statically or semi-statically configured cell identifiers808, which may be denoted by the set:
{x(0),x(1), . . .x(N−1)}, forN>1.
The values of x(n), where 0≤n<N may be configured by UE-specific RRC signaling810. The parameter X may be dynamically signaled through additional bits provided in DCI828or through the reuse of an existing parameter such as nSCID. When the set {x(0), x(1), . . . x(N−1)}, from which X is selected, has more than one member, then an index used to select a member may be obtained through dynamic signaling, including through direct signaling of index bits in DCI828or by generating an index based on one or more properties of the DCI828.

An index n may be directly signaled to UE802for selecting a value of X=x(n) from the set {x(0), . . . , x(N−1)}, which may be populated using a plurality of semi-statically configured virtual cell identifiers808. The index may be provided to the UE802using additional bits provided in a grant, or by reusing existing bits such as scrambling identity (SCID) bit. As described elsewhere herein, the index may be provided by direct signaling when DCI828has certain properties

Additionally, or alternatively, the index or other indicator may be provided through dynamic signaling. Dynamic signaling may include modifying an attribute or property of a signal that is otherwise used for purposes unrelated to the selection of a cell identifier. In certain embodiments, one or more properties of DCI828transmitted by eNB804may be used to convey the index or otherwise indicate which of cell identifiers808should be selected by UE802for configuring an aspect of UE802operation. The one or more properties may relate to a type of DCI format814,816, or818, a type of downlink control channel820,822used to carry the DCI828, and a type of subframe824,826that carries the DCI828.

An index may be generated using criteria that may include certain properties of the DCI828, specifically assigned bits in the DCI828, reused bits in the DCI828, and other statically configured information. Some dynamically signaled information may narrow down a selection of virtual cell identifiers and other criteria may then be used to make a final selection.

Information signaled directly in DCI828and knowledge of a format type814,816, and818of the DCI828may be combined to indicate a cell identifier to the UE802. DCI828may have different formats, including Type 1A814, Type 2C816, and Type 2D818, among others, which define certain structures, fields and other attributes of the DCI828. The examples of DCI format types (1A, 2C, and 2D) are selected to simplify illustration, and the principles described in relation thereto apply equally to other DCI format types, including format types defined by current and future wireless communication protocols. DCI format types814,816and818may define or relate to certain capabilities of a UE802or eNB804. Some DCI types816and818may carry one or more bits specifically assigned to serve as an index or identifier, and may thereby directly indicate a selection to the UE802. Accordingly, UE802may determine that an index is provided in DCI payload812when DCI828has a certain format. If, for example, DCI828is transmitted with Type 2C or Type 2D format, then an index or other indicator may be coded in the DCI payload812to enable direct signaling of an index or other indicator to UE802. However, if DCI828is transmitted with Type 1A format, directly signaled bits may not be available and other information related to the transmission may be needed to select a cell identifier808. When DCI828has a Type 1A format814, the index used to select one of cell identifiers808may be set to a predetermined value. In some embodiments, a predefined cell identifier is used when DCI828has a Type 1A format814.

In some embodiments, the UE802may determine an index or a predetermined cell identifier based on the type of downlink control channel820,822and/or type of subframe824,826that carries the DCI828when, for example, a received DCI828has a Type 1A format814. For example, when the DCI828is carried in enhanced PDCCH (ePDCCH)822, one or more bits may be directly embedded in the ePDCCH822to serve as an index for selecting between statically or semi-statically defined cell identifiers808. In some embodiments, a scrambling identifier used for scrambling the ePDCCH822may serve as the cell identifier808, or as an index to select one of statically or semi-statically defined cell identifiers808.

When Type 1A formatted DCI828is carried in legacy PDCCH820, then the UE802may select a predetermined cell identifier, which may be included in the statically or semi-statically defined cell identifiers808. The predetermined cell identifier may be included in a predefined location in statically or semi-statically defined cell identifiers808and may be accessed using a predefined index value, such as an index n=0. In some embodiments, the predetermined cell identifier may be identified in the statically or semi-statically defined cell identifiers808using an index that is statically configured for the UE802. In some embodiments, the predetermined cell identifier may be statically configured. In some embodiments, the predetermined cell identifier may be a physical cell identifier, such as the identifier of a serving cell identified by the UE802.

In some embodiments, the UE802may determine an index or a predetermined cell identifier based on the type of subframe that carries DCI828. For example, the index may be determined based in part upon whether the DCI828is received in an MBSFN subframe824or a non-MBSFN subframe826. In particular, the type of subframe824or826used to carry DCI828may limit the information available for selecting a cell identifier at the UE802. For example, when DCI828is carried in a non-MBSFN type826subframe, information may be available to UE802for selecting a virtual cell identifier only if DCI format Type 2C816or Type 2D818is used or if the DCI828is provided in ePDCCH822. When DCI Type 1A format814is received in a PDCCH820of a non-MBSFN subframe826, then the index may be set to a predetermined value or a predefined cell identifier may be used. The predefined cell identifier may be a physical cell identifier. In another example, when DCI type 1A format814is used to signal DCI828in a PDSCH transmission, the UE802may be informed of the virtual cell identifier using a combination of specially assigned bits and bits that are defined for other use (e.g. the SCID bit).

In non-MBSFN subframes826, a CRS-based fallback transmission mode may be used. The use of a fallback transmission mode may require that the UE802be informed of a physical cell identifier to be used. This physical cell identifier may be tied to the serving cell for transmissions using legacy PDCCH820. In some embodiments, the physical cell identifier is signaled separately.

In some embodiments, when non-MBSFN subframes826carry the DCI828, a fallback mode may be used that employs DM-RS based demodulation. The signaling of virtual cell identifiers to be used for DM-RS scrambling may be similar to the signaling discussed in connection with DCI828carried in MBSFN824subframes. For example, port7may be used in this operation, similar to the existing transmission mode9.

A determination of which fallback mode should be used during DM-RS based fallback transmission mode may be based, at least in part, on whether control is received through legacy PDCCH820or ePDCCH822. For example, a DM-RS based fallback transmission mode may be used whenever control is received through the ePDCCH822and a CRS-based fallback transmission may be used when control is received on the legacy PDCCH820.

In some embodiments, fallback operation may be based on a predetermined cell identifier, which may be a physical cell identifier. For example, an ePDCCH822configured for a UE802may rely entirely on one or more virtual cell identifiers808, and the eNB804and the UE802may be out of synchronization when a reconfiguration of virtual cell identifiers is initiated for the UE802. Potential ambiguity and misalignment can be alleviated by specifying cell identifiers for the UE802that include one or more virtual cell identifiers associated with certain control decoding candidates and one or more physical cell identifiers associated with other control decoding candidates.

In an MBSFN subframe824, a predetermined virtual cell ID may be used when control is received through either of the PDCCH820or ePDCCH822for DCI Type 1A format814. The predetermined virtual cell identifier may be indicated using an index known to the UE802, for example, index n=0. When the DCI828is received on ePDCCH822in an MBSFN subframe824, an ePDCCH scrambling identifier may be used. The ePDCCH scrambling identifier may be one of a plurality of identifiers available when the ePDCCH822supports different scrambling initializations. An index may be formed using an entire ePDCCH scrambling identifier or a subset of the bits in the ePDCCH scrambling identifier. In some embodiments, ePDCCH822carries bits based on DCI type 1A format that may be used to signal a virtual cell identifier in use for PDSCH.

Other properties of DCI828may be used by UE802to select a cell identifier. In some embodiments, the selection of a cell identifier may be based, at least in-part on the control channel in which DCI828is found during a search of a plurality of candidate control channels (CCEs). The search space may be partitioned into a set of CCEs and a virtual cell ID808may be selected, at least in part, based on the partition in which the DCI828is received.

As described herein, dynamic signaling may identify virtual cell identifiers and physical cell identifiers. In some embodiments, the partitioning of virtual cell identifier based control and physical cell identifier based control may depend on whether the UE802is configured to monitor ePDCCH822only, or monitor a combination of ePDCCH822and PDCCH820. In the former case, some ePDCCH822decoding candidates may rely on one or more virtual cell identifiers808, and some other ePDCCH decoding candidates may rely on a physical cell identifier. In the latter case, where UE802monitors both PDCCH820and ePDCCH822, all ePDCCH822may rely on virtual cell identifiers808, while at least some PDCCH820decoding candidates may rely on a physical cell identifier.

Partitioning of virtual cell identifier based control and physical cell identifier based control may also be subframe-dependent, aggregation-level dependent, search space dependent, with differentiation between common and UE-specific search spaces for example, DCI format dependent, etc. In one example, a physical cell identifier may be used for ePDCCH822based DCI format 1A814in some subset of subframes (e.g., subframes0,4,5and9), while one or more virtual cell identifiers are used for ePDCCH822in all other cases.

Certain aspects of the invention may be applied to uplink signaling. In some embodiments, one or more of virtual cell identifiers808may be configured for the uplink. Dynamic signaling may be used to select which of the cell identifiers808should be used for a specific subframe. This dynamic signaling may take advantage of additional bits available in certain DCI formats816and818, and may also be based specifically on the type of DCI format used (e.g., DCI format Type 0 vs. DCI format Type 4) or some combination of payload812and format of the DCI828. In one example, DCI format Type 4 may provide one or more bits that are not available in DCI format Type 0. The additional bits in DCI format Type 4 may be used or assigned to determine the virtual cell identifier for use in uplink transmission, while a predetermined virtual cell identifier may be used when DCI format Type 0 is received.

In some embodiments, determination of a virtual cell identifier may be based, at least in part, on whether the DCI828is received through ePDCCH822or a PDCCH820. For example, use of DCI format Type 0 may indicate to the UE802that a physical cell identifier should be used for fallback operation, while DCI format Type 4 may indicate that virtual cell identifier should be used. For retransmissions, the UE802may use the same virtual cell identifier that was used for the initial transmission.

Dynamic signaling may be used to select other parameters used for configuring a UE802. Configuration information that may be semi-statically configured and selected using dynamic signaling may include locations in control or data region used for hybrid ARQ indicator channel (PHICH) information and virtual cell identifiers for transmission of channel state information (CSI) information carried in PUCCH.

Certain embodiments employ dynamic signaling and identifier selection for Hybrid ARQ indication. Legacy PHICH transmission may be accommodated in a corresponding legacy control region and an “enhanced PHICH” (ePHICH) may be supported as part of ePDCCH822and may be carried in the data region. A combination of parameters may be employed by the UE802to determine where HARQ indication corresponding to its uplink transmissions can be found. The parameters may include DCI format type, subframe type, PDCCH type, and search space partitioning. In one example, the UE802may look for the PHICH in the legacy control region when a grant associated with an uplink PUSCH transmission is received on the legacy PDCCH820. If the grant is received on ePDCCH822, the UE802may look for an ePHICH in the data region. In another example, the type of grant that triggered the uplink transmission may provide additional indication to the UE802as to where the Hybrid ARQ indication may be found.

Certain embodiments employ dynamic signaling and identifier selection for uplink PUCCH transmissions. In one example, for uplink transmission of HARQ ACK/NACK information, the UE802may take advantage of additional bits available in certain DCI formats and may also be based on the specific DCI format type814,816or818used, as well as whether control is received through ePDCCH822or legacy PDCCH820to determine a virtual cell identifier. In some embodiments, the UE802may use the same virtual cell identifier for uplink ACK/NACK transmission that was used for downlink signaling. Other mappings may also be performed, and the mapping may depend upon a combination of parameters including DCI format type, downlink control channel type, subframe type, or by an explicit indication in DCI828. When multiple types of uplink control information are multiplexed on PUCCH, a common virtual cell ID808may be selected for transmission according to a predetermined prioritization.

Certain embodiments employ dynamic signaling and identifier selection for feedback of CSI information. In one example, a virtual cell identifier may be configured for use in transmitting aperiodic feedback on PUSCH as part of the feedback configuration, and/or may be selected based on one or more parameters, including explicit bits provided in a DCI format requesting the aperiodic CSI report, DCI format type, and the type of control channel that delivers the grant requesting the aperiodic report. The type of control channel may be legacy PDCCH820, or ePDCCH822, for example.

A combination of semi-static and dynamic signaling may be employed to determine a virtual cell identifier808for transmitting the CSI feedback. The selected virtual cell identifier selected for transmission of periodic CSI feedback carried on PUCCH may be configured as part of the feedback configuration. In some embodiments, the virtual cell identifier selected for transmitting PUCCH multiplexed with other uplink control information may be based on other components of the multiplexed transmission or the multiplexed transmission itself.

In certain embodiments, cell identifiers808may comprise one or more physical cell identifiers in addition to one or more virtual cell identifiers, particularly for use during fallback operations and/or to avoid ambiguity whenever a reconfiguration of virtual cell identifiers is initiated. For example, a physical cell identifier may be used when a set of virtual cell identifiers used in conjunction with dynamic selection is configured through RRC810.

In certain embodiments, one or more virtual cell identifiers used for uplink operation may each be replaced by an index for selecting a set of parameters that are used together in place of the virtual cell ID. The set of parameters may define one or more characteristics of a virtual cell. The set of parameters may individually define characteristics, attributes, parameters and/or behaviors that would otherwise be defined by the virtual cell. In particular, this set of parameters may include a value NIDBSIwhich may substitute NIDCELLfor initiating a pseudo-random sequence generator, DSSBSIwhich may substitute group number (u) and sequence index (v) generation formulas (including SH and SGH initialization), and cinitCSHwhich may serve as a substitute cinitin the CSH initialization (nPN(nS)).

Table 1 below describes methods by which an index, a cell identifier or other information can be signaled to a UE802from an eNB804according to certain aspects of the invention.

FIG. 9is a flow chart900of a method of wireless communication. The method may be performed by a UE802. At step902, the UE802receives a plurality of cell identifiers through RRC signaling. In some embodiments, the UE802may receive other configuration information through the RRC810signaling.

At step904, the UE802receives a signal including DCI828. The DCI828may be received in an ePDCCH822or a PDCCH820. In some embodiments, receiving a signal includes receiving the DCI828in a first set of candidate control channels (CCEs) of at least two sets of CCEs. The selected cell identifier may be selected, at least in part, based on the set of CCEs in which the DCI828is received.

At step906, the UE802selects one of the plurality of cell identifiers based on one or more properties associated with the DCI. In some embodiments, the one or more properties are not exclusively associated with determining a cell identifier. The properties may include a control channel in which DCI828is delivered, a type of the DCI828and the subframe type that carries the DCI828.

At step908, if the DCI format type provides bits that carry an index or other indicator, then the UE802may select a cell identifier using the bits and the UE802initializes a pseudo-random sequence generator using the selected cell identifier at step922.

If the DCI format type does not support direct signaling of an index or other indicator, then at step910, the UE802determines whether the DCI828is carried in an ePDCCH822. If the DCI828is carried in a PDCCH820, then the UE802may determine a cell identifier based on whether at step912it is determined that the DCI is carried in an MBSFN subframe824. If an MBSFN subframe824is the type of subframe used, then the UE802may use a predetermined cell identifier to initialize a pseudo-random sequence generator at step924. Otherwise, the UE802may initialize the pseudo-random generator using a physical cell identifier at step918.

At step914, it is determined whether the ePDCCH822is scrambled with an ePDCCH scrambling identifier and, if so, it is determined if the UE802should use the ePDCCH scrambling identifier to initialize a pseudo-random sequence generator at step920. If it is determined that the UE802should not use the ePDCCH scrambling identifier as a virtual cell identifier or for initializing the pseudo-random generator, the at step916, the UE802determines whether the generator should be initialized using bits transmitted in the ePDCCH at step922, or using a predetermined identifier at step924.

In some embodiments, the DCI828includes an uplink grant. The selected cell identifier may be used for an uplink transmission corresponding to the uplink grant.

In some embodiments, channel state information (CSI) may be provided based on the selected cell identifier.

FIG. 10includes a flow chart1000of a method of wireless communication. The method may be performed by a UE802. At step1002, the UE802receives a signal including DCI that includes an uplink grant. The DCI may be received in one of a PDCCH or an ePDCCH. At step1004, the UE802determines if the control channel providing the grant is a PDCCH and, if so, may identify PHICH in a control region at step1012. If at step1004, the UE determines the control channel to be ePDCCH, the UE may identify an ePHICH in a data region at step1006.

At step1008, the UE802selects one of a plurality of cell identifiers based on a property associated with the DCI. The property may not be exclusively related to determining a cell identifier.

At step1010, the UE802provides an acknowledgement or a negative acknowledgement based on the selected cell identifier.

FIG. 10includes a flow chart1020of a method of wireless communication. The method may be performed by a UE802. At step1022, the UE802determines an index based on a format type of DCI. At step1024, the UE selects a set of parameters from a plurality of sets of the parameters based on the index. The set of parameters may define one or more characteristics of a virtual cell. The plurality of sets of the parameters is configured through RRC signaling.

FIG. 11includes a flow chart1100of a method of wireless communication. The method may be performed by an eNB804. At step1102, eNB804provides a plurality of identifiers in radio resource control (RRC) signaling to the UE802. The indicated cell identifier may be one of the plurality of identifiers808.

The eNB804configures one or more properties of DCI. A UE802may be adapted to determine a cell identifier indicated by the configured properties. However, the configured properties may not be exclusively associated with determining the cell identifier. The UE802may be adapted to use the indicated cell identifier to initialize a pseudo-random sequence generator. At step1104, eNB804, configures a format type of the DCI. At step1106, eNB804selects a control channel to carry the DCI. The DCI may be transmitted in an ePDCCH that is scrambled with an ePDCCH scrambling identifier and the indicated cell identifier may be the ePDCCH scrambling identifier when the DCI has a type 1A format.

At step1108, the eNB804selects a subframe type for the DCI. The DCI may be provided in an MBSFN subframe or a non-MBSFN subframe. The cell identifier may be indicated based on the subframe type. The DCI may include an uplink grant, and the indicated cell identifier may be used for an uplink transmission corresponding to the uplink grant. The selected cell identifier may be used to provide CSI.

At step1110, the eNB804transmits a signal including the DCI to the UE802.

FIG. 11includes a flow chart1120of a method of wireless communication. The method may be performed by an eNB804. At step1122, eNB804configures one or more properties of the DCI. The UE802may be adapted to determine a location in which PHICH is transmitted by the eNB804, based on the configured properties.

At step1124, eNB804transmits a signal including DCI that includes an uplink grant to a UE802. The DCI may be transmitted in one of a PDCCH or an ePDCCH.

At step1126, eNB804receives an uplink data or control transmission from the UE, in accordance with the uplink grant.

At step1128, eNB804sends an ACK or a NACK in a PHICH in a control region or in an ePHICH in a data region based on whether the grant was provided in the PDCCH or in the ePDCCH.

FIG. 12is a conceptual data flow diagram1200illustrating the data flow between different modules/means/components in an exemplary apparatus1202. The apparatus may be a UE. The apparatus1202includes a module1204that receives DCI, a module1206that selects a cell identifier, a module1208that initializes a random sequence generator, a module1210that receives RRC, a module1212that provides CSI feedback and a module1214that transmits to an eNB804using transceiver1250.

FIG. 13is a diagram1300illustrating an example of a hardware implementation for an apparatus1202′ employing a processing system1314. The processing system1314may be implemented with a bus architecture, represented generally by the bus1324. The bus1324may include any number of interconnecting buses and bridges depending on the specific application of the processing system1314and the overall design constraints. The bus1324links together various circuits including one or more processors and/or hardware modules, represented by the processor1304, the modules1204,1206,1208,1210,1212, and1214, and the computer-readable medium1306. The bus1324may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system1314may be coupled to a transceiver1310. The transceiver1310is coupled to one or more antennas1320. The transceiver1310provides a means for communicating with various other apparatus over a transmission medium. The processing system1314includes a processor1304coupled to a computer-readable medium1306. The processor1304is responsible for general processing, including the execution of software stored on the computer-readable medium1306. The software, when executed by the processor1304, causes the processing system1314to perform the various functions described supra for any particular apparatus. The computer-readable medium1306may also be used for storing data that is manipulated by the processor1304when executing software. The processing system further includes at least one of the modules1204,1206,1208,1210,1212, and1214. The modules may be software modules running in the processor1304, resident/stored in the computer readable medium1306, one or more hardware modules coupled to the processor1304, or some combination thereof. The processing system1314may be a component of the UE650and may include the memory660and/or at least one of the TX processor668, the RX processor656, and the controller/processor659.

In one configuration, the apparatus1202/1202′ for wireless communication includes means1204for receiving a signal including DCI, means1206for selecting one of a plurality of cell identifiers based on one or more properties associated with the DCI, means1208for initializing a pseudo-random sequence generator based on the selected cell identifier, means1210for receiving the plurality of cell identifiers via RRC signaling, means1212for providing CSI based on the selected cell identifier, and means1214for transmitting information to the eNB804.

In some embodiments, the one or more properties are not exclusively associated with determining a cell identifier. In some embodiments, the DCI is received in ePDCCH. The ePDCCH may be scrambled with an ePDCCH scrambling identifier. In some embodiments, means1206determines a type of format of the DCI, and selects the selected cell identifier based on the ePDCCH scrambling identifier when the DCI has a type 1A format. In some embodiments, means1206determines a type of format of the DCI and selects a predetermined cell identifier when the DCI has a type 1A format. In some embodiments, means1206determines a subframe type in which the DCI is received, and further determines whether the subframe is a MBSFN subframe or a non-MBSFN subframe. The cell identifier may be selected, at least in part, based on the subframe type.

In some embodiments, means1204receives the DCI in a first set of candidate control channels (CCEs) of at least two sets of CCEs, and the selected cell identifier may be selected, at least in part, based on the set of CCEs in which the DCI is received. The DCI may include an uplink grant. In some embodiments, the selected cell identifier is used for an uplink transmission corresponding to the uplink grant.

The aforementioned means may be one or more of the aforementioned modules of the apparatus1202and/or the processing system1314of the apparatus1202′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system1314may include the TX Processor668, the RX Processor656, and the controller/processor659. As such, in one configuration, the aforementioned means may be the TX Processor668, the RX Processor656, and the controller/processor659configured to perform the functions recited by the aforementioned means.

FIG. 14is a conceptual data flow diagram1400illustrating the data flow between different modules/means/components in an exemplary apparatus1402. The apparatus may be an eNB804. The apparatus includes a module1404that configures DCI828, a module1406that selects one of a PDCCH820or ePDCCH822to carry the DCI828, a module1408that selects between an MBSFN subframe824and a non-MBSFN subframe826for transmitting the DCI828, a module1410for providing statically or semi-statically configured parameters in RRC810, and a transmission module1412that transmits DCI828and RRC810to UE802through transceiver1450.

FIG. 15is a diagram1500illustrating an example of a hardware implementation for an apparatus1402′ employing a processing system1514. The processing system1514may be implemented with a bus architecture, represented generally by the bus1524. The bus1524may include any number of interconnecting buses and bridges depending on the specific application of the processing system1514and the overall design constraints. The bus1524links together various circuits including one or more processors and/or hardware modules, represented by the processor1504, the modules1404,1406,1408,1410,1412, and the computer-readable medium1506. The bus1524may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system1514may be coupled to a transceiver1510. The transceiver1510is coupled to one or more antennas1520. The transceiver1510provides a means for communicating with various other apparatus over a transmission medium. The processing system1514includes a processor1504coupled to a computer-readable medium1506. The processor1504is responsible for general processing, including the execution of software stored on the computer-readable medium1506. The software, when executed by the processor1504, causes the processing system1514to perform the various functions described supra for any particular apparatus. The computer-readable medium1506may also be used for storing data that is manipulated by the processor1504when executing software. The processing system further includes at least one of the modules1404,1406,1408,1410, and1412. The modules may be software modules running in the processor1504, resident/stored in the computer readable medium1506, one or more hardware modules coupled to the processor1504, or some combination thereof. The processing system1514may be a component of the eNB610and may include the memory676and/or at least one of the TX processor616, the RX processor670, and the controller/processor675.

In one configuration, the apparatus1402/1402′ for wireless communication includes means1404for configuring one or more properties of DCI828. UE802may be adapted to determine a cell identifier indicated by the configured properties. The configured properties may not be exclusively associated with determining the cell identifier. Means1404may configure a format type of the DCI828. Means1404may select a control channel for transmitting the DCI828, whereby the cell identifier is indicated, at least in part, by the control channel selection

The apparatus1402/1402′ for wireless communication may include means1412for transmitting a signal including the DCI828to the UE802.

The apparatus1402/1402′ for wireless communication may include means1410for providing a plurality of identifiers808in RRC810signaling to the UE802, whereby the indicated cell identifier is one of the plurality of identifiers808. The UE802may be adapted to use the indicated cell identifier to initialize a pseudo-random sequence generator.

The apparatus1402/1402′ for wireless communication may include means1406for transmitting the DCI828in an ePDCCH822that is scrambled with an ePDCCH scrambling identifier. The indicated cell identifier may be equal to the ePDCCH scrambling identifier when the DCI828has a type 1A format814, for example. In some embodiments, the indicated cell identifier is a predetermined cell identifier when the DCI828has a type 1A format814.

The apparatus1402/1402′ for wireless communication may include means1408for transmitting the DCI828in one of a MBSFN subframe824and a non-MBSFN subframe826. The cell identifier may be indicated based on the subframe type824or826.

In some embodiments, the DCI828includes an uplink grant, and the indicated cell identifier may be used for an uplink transmission corresponding to the uplink grant. In some embodiments, the selected cell identifier is to be used to provide CSI. In certain embodiments, means1412transmits an ACK or a NACK in a PHICH in a control region when the grant is provided in the PDCCH820, and transmits the ACK or the NACK in an enhanced PHICH in a data region when the grant is provided in the ePDCCH822.

The aforementioned means may be one or more of the aforementioned modules of the apparatus1402and/or the processing system1514of the apparatus1402′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system1514may include the TX Processor616, the RX Processor670, and the controller/processor675. As such, in one configuration, the aforementioned means may be the TX Processor616, the RX Processor670, and the controller/processor675configured to perform the functions recited by the aforementioned means.