Managing interference in a network

A method, an apparatus, and a computer program product for wireless communication are provided. In one configuration, the apparatus may be a UE. The UE determines an MCS that would facilitate interference suppression of an interfering first cell transmission from a first cell when decoding a second cell transmission from a second cell at the UE. The interfering first cell transmission is a transmission unintended for the UE. The second cell transmission is a transmission intended for the UE. The UE transmits information indicating the determined MCS for the first cell. The UE receives a transmission including the second cell transmission from the second cell and the interfering first cell transmission from the first cell. The UE demodulates and/or decodes the second cell transmission from the received transmission based on the determined MCS.

BACKGROUND

Field

The present disclosure relates generally to communication systems, and more particularly, to managing interference in a network.

Background

SUMMARY

In an aspect of the disclosure, a method, a computer program product, and an apparatus are provided. The apparatus may be a user equipment (UE). The UE determines a modulation and coding scheme (MCS) that would facilitate interference suppression of an interfering first cell transmission from a first cell when decoding a second cell transmission from a second cell at the UE. The interfering first cell transmission is a transmission unintended for the UE. The second cell transmission is a transmission intended for the UE. The UE transmits information indicating the determined MCS for the first cell. The UE receives a transmission including the second cell transmission from the second cell and the interfering first cell transmission from the first cell. The UE demodulates the second cell transmission from the received transmission based on the determined MCS. The UE may demodulate and/or decode the second cell transmission from the received transmission based on an assumption that the interfering first cell transmission is at least one of modulated or encoded based on the determined MCS.

In an aspect of the disclosure, a method, a computer program product, and an apparatus are provided. The apparatus may be a cell. The cell receives information indicating an MCS that would facilitate interference suppression by a first UE of a cell transmission from the cell. The cell performs at least one of modulating or encoding data based on the received information indicating the MCS. The cell transmits the data in the cell transmission to a second UE.

DETAILED DESCRIPTION

The E-UTRAN includes the evolved Node B (eNB)106, other eNBs108, and a Multicast Coordination Entity (MCE)128. The eNB106provides user and control planes protocol terminations toward the UE102. The eNB106may be connected to the other eNBs108via a backhaul (e.g., an X2 interface). The MCE128allocates time/frequency radio resources for evolved Multimedia Broadcast Multicast Service (MBMS) (eMBMS), and determines the radio configuration (e.g., a modulation and coding scheme (MCS)) for the eMBMS. The MCE128may be a separate entity or part of the eNB106. The eNB106may also be referred to as a base station, a Node B, an access point, 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, a tablet, 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 to the EPC110. The EPC110may include a Mobility Management Entity (MME)112, a Home Subscriber Server (HSS)120, other MMEs114, a Serving Gateway116, a Multimedia Broadcast Multicast Service (MBMS) Gateway124, a Broadcast Multicast Service Center (BM-SC)126, 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 Gateway118and the BM-SC126are connected to the IP Services122. The IP Services122may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service (PSS), and/or other IP services. The BM-SC126may provide functions for MBMS user service provisioning and delivery. The BM-SC126may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a PLMN, and may be used to schedule and deliver MBMS transmissions. The MBMS Gateway124may be used to distribute MBMS traffic to the eNBs (e.g.,106,108) belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

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. An eNB may support one or multiple (e.g., three) cells (also referred to as a sectors). The term “cell” can refer to the smallest coverage area of an eNB and/or an eNB subsystem serving are particular coverage area. Further, the terms “eNB,” “base station,” and “cell” may be used interchangeably herein.

Channel estimates derived by a channel estimator658from a reference signal or feedback transmitted by the eNB610may be used by the TX processor668to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor668may be provided to different antenna652via separate transmitters654TX. Each transmitter654TX may modulate an RF carrier with a respective spatial stream for transmission.

FIG. 7is a diagram700illustrating a range expanded cellular region in a heterogeneous network, including an aspect for managing interference. A lower power class eNB such as the pico eNB710bmay have a range expanded cellular region703that is expanded from the cellular region702through enhanced inter-cell interference coordination between the pico eNB710band the macro eNB710aand through interference cancelation performed by the UE720. In enhanced inter-cell interference coordination, the pico eNB710breceives information from the macro eNB710aregarding an interference condition of the UE720. The information allows the pico eNB710bto serve the UE720in the range expanded cellular region703and to accept a handoff of the UE720from the macro eNB710aas the UE720enters the range expanded cellular region703.

A UE may employ advanced decoding algorithms such as joint decoding of serving and interferer data (e.g., PDSCH) or interference cancelation (IC) of interferer transmissions for enabling the demodulating and decoding of serving cell data (e.g., PDSCH). In codeword level interference cancelation (CWIC), a UE attempts to decode an interfering transmission from a received transmission that includes both the interfering transmission and the serving base station transmission. Based on the decoded interfering transmission, the UE cancels the interfering transmission from the received transmission. The UE then demodulates and decodes the serving base station transmission from the interference canceled received transmission. In symbol level IC (SLIC), a UE estimates symbols transmitted by the interfering base station and cancels the interfering transmission from the received transmission based on the estimation. The UE then demodulates and decodes the serving base station transmission from the interference canceled received transmission.

When the MCS of the interfering PDSCH is picked independently of the UE that attempts to cancel the PDSCH, a UE may receive one or more interfering PDSCHs at signal to interference plus noise ratio (SINR) values not suitable for performing joint decoding or successive interference cancelation. The UE may then have to revert to single user decoding in which the UE treats the interfering transmission as noise. For example, the interfering PDSCH may have an MCS that is too high to decode correctly at the UE for CWIC or any other joint decoding or successive interference cancelation algorithm.

In a first exemplary method, the UE720determines an MCS that would facilitate interference suppression of an interfering transmission714from the eNB710a(interfering base station). Interference suppression includes one or more of interference cancelation (e.g., CWIC or SLIC), reduced complexity maximum likelihood (R-ML) decoding in a network assisted inference cancelation (NAIC) context, and other techniques that allow the UE to exploit knowledge of parameters or statistics of the parameters of an interfering transmission714. The UE720transmits information740indicating the determined MCS for the eNB710a. The UE720may transmit the information740directly to the eNB710aor may transmit the information740to the pico eNB710b, which then provides the information740to the eNB710a. The eNB710areceives the information740indicating the MCS that would facilitate interference suppression by the UE720of the interfering transmission714from the eNB710a. The eNB710athen modulates and/or encodes data (e.g., PDSCH) based on the received information740indicating the MCS. The eNB710asubsequently transmits the data to the UE722, thereby generating the interfering transmission714.

The UE720receives a transmission712,714including a serving base station transmission712from the pico eNB710b(serving base station) and the interfering transmission714from the eNB710a. The UE720demodulates and/or decodes the serving base station transmission712from the received transmission712,714based on an assumption that the interfering transmission714is modulated and/or encoded based on the determined MCS. In one configuration, before demodulating and decoding the serving base station transmission712, the UE720suppresses, from the received transmission712,714, interference to the serving base station transmission712by the interfering transmission714. The UE720may suppress the interference to the serving base station transmission712based on the determined MCS.

In one configuration, the UE720determines a channel quality indicator (CQI) associated with the determined MCS. In such a configuration, the information740indicating the determined MCS is information indicating the determined CQI. The information indicating the determined CQI may include at least one of a wideband CQI, a subband CQI for one or more subbands, a most preferred precoding matrix indicator (PMI), a least preferred PMI, or a rank indicator (RI). A least preferred PMI is one that causes minimum interference at the UE720. The UE720may choose not to perform interference suppression, or may be unable to perform interference suppression, if the least preferred PMI is used. A most preferred PMI is one that maximizes interference at the UE720, or otherwise increases interference to a level that can be detected, demodulated, decoded, or otherwise suppressed at the UE. Maximizing interference at the UE720may help the UE720with interference suppression, and in particular, with decoding the interfering signal. The PMI may be unnecessary if the eNB710auses transmission mode (TM)3. With respect to the RI, the UE720may force RI to equal 1 for reasons such as implementation complexity and/or interference suppression accuracy.

The UE720may compute the CQI for a particular advanced decoding algorithm at the UE720, such as joint decoding or successive interference cancelation. The UE720may determine the MCS corresponding to the CQI such that the UE can successfully demodulate and decode the serving base station transmission712using its advanced decoding algorithm. The number of interfering base stations with which the UE720performs the exemplary method may depend on receiver capability, the decoding algorithm implemented at the UE, signaling overhead, and other factors.

The eNB710amay send the interfering transmission714that is modulated and/or encoded based on the determined MCS in particular predetermined subframes and/or subbands. Accordingly, the UE720may determine subframes and/or subbands on which the interfering transmission714will be modulated and encoded based on the determined MCS. The UE720may then determine whether to suppress interference from the received transmission712,714based on whether the transmission is received in the determined subframes and/or subbands.

The eNB710amay schedule UEs for receiving a downlink transmission based on the received information740indicating the MCS. The eNB710amay schedule UEs for receiving a downlink transmission based on whether the UEs are able to receive the downlink transmission at the determined MCS. If the eNB710adetermines that the UE722can receive the interfering transmission714at the determined MCS, the eNB710amay schedule the UE722to receive the interfering transmission714.

As discussed supra, the eNB710amodulates and/or encodes the interfering transmission714based on the determined MCS. The eNB710amay modulate and/or encode the interfering transmission714with the determined MCS. Alternatively, the eNB710amay modulate and/or encode the interfering transmission714with an MCS equal to or lower than the determined MCS. In one configuration, the eNB710adetermines the MCS for modulating and/or encoding the interfering transmission714based on a predetermined maximum MCS.

When the eNB710amodulates and/or encodes the interfering transmission714based on a predetermined maximum MCS or with an MCS equal to or lower than an MCS received (directly or indirectly) from the UE720, the pico eNB710bmay schedule UEs so that they can reliability suppress the interference from the eNB710a. Accordingly, the UE720may receive downlink grants from the pico eNB710bin which the downlink grants are based on the determined MCS utilized by the eNB710a. The pico eNB710bmay schedule the UE720when the eNB710auses an MCS less than or equal to the MCS determined by the UE720, and may refrain from scheduling the UE720when the eNB710auses an MCS that is greater than the MCS determined by the UE720.

The UE720may determine the MCS for the eNB710abased on an SINR associated with reference signals received from the eNB710a. If the UE720is implementing successive SLIC, the UE720may determine a modulation order that the UE720can reliably suppress/cancel based on the SINR of the reference signals received from the eNB710a. The UE720then determines a highest MCS associated with the determined modulation order. The UE720indicates the determined highest MCS in the information740. If the UE720is implementing successive CWIC, the UE720determines an MCS that the UE720can reliably suppress/cancel based on the SINR of the reference signals received from the eNB710a. The UE720indicates the determined MCS in the information740. The UE720may adjust the determined MCS based on a previously determined MCS and an accuracy of a previous suppression of interference based on the previously determined MCS.

The reference signals may be CRS or channel state information (CSI) RS (CSI-RS) transmitted from the eNB710a. When determining the SINR associated with reference signals received from the eNB710a, the UE720may estimate the noise based on CRS transmissions from the pico eNB710band/or based on CSI-RS using interference management resources (IMRs).

The UE720sends the information740directly to the eNB710aor to the pico eNB710b, which may then forward the information740to the eNB710a. If the pico eNB710breceives the information740, the pico eNB710bmay aggregate all MCS/CQI reports from served UEs (including the UE720) and send one or more MCS/CQI reports to the eNB710aof a function ƒ of the MCS/CQI reports to the eNB710a. The function ƒ may include just the minimum of all MCS/CQI reports or the kthpercentile of the MCS/CQI reports (e.g., 20%, 50%, etc).

The UE720may determine whether a previous interference suppression was successful, and transmit an ACK when the previous interference suppression is determined to be successful and transmit a NACK when the previous interference suppression is determined to be unsuccessful. The UE720may transmit the ACK/NACK750to the eNB710aor to the pico eNB710b. The pico eNB710bmay forward the ACK/NACK to the eNB710a. When reported to the eNB710a, the eNB710amay bias the MCS used for modulating and/or encoding the interfering transmission714. When reported to the pico eNB710b, the pico eNB710bmay bias the MCS in the aggregated reports.

An example best demonstrates the exemplary method. Assume a CWIC capable UE receives a single data transmission including data transmissions from a serving eNB, a first interfering eNB, and a second interfering eNB. Further, assume the SNR from the serving eNB is 10 dB, the SNR from the first interfering eNB is 20 dB, and the SNR from the second interfering eNB is 13 dB. For simplicity, assume also that the UE can perform perfect cancelation if the UE can decode the signal to be canceled (possible with perfect channel estimation). For a single user decoding with additive white Gaussian noise (AWGN) interference, the serving CQI corresponds to an SINR of approximately −11 dB. The SNR is equal to 10 log10X, where X is the power ratio. As such, an SNR of 10 dB corresponds to a power ratio of 10. An SNR of 20 dB corresponds to a power ratio of 100 and an SNR of 13 dB corresponds to a power ratio of approximately 20. For single user decoding with AWGN interference, the SINR corresponds to a power ratio of 10/(100+20), which corresponds to an SINR of approximately −11 dB. However, for CWIC decoding with decoding order being (1) the first interfering eNB, (2) the second interference eNB, and (3) the serving eNB, a UE reports a CQI for the first interfering eNB corresponding to an SINR of approximately 5 dB (i.e., an SINR corresponding to a power ratio of 100/(20+10), a CQI for the second interfering eNB corresponding to an SINR of approximately 3 dB (i.e., an SINR corresponding to a power ratio of 20/10), and a CQI for the serving eNB of 10 dB. If the first interfering eNB modulates and encodes its interfering data transmission based on an MCS/CQI corresponding to an SINR of 5 dB and the second interfering eNB modulates and encodes its interfering data transmission based on an MCS/CQI corresponding to an SINR of 3 dB, a UE that receives the interfering transmissions in a data transmission that also includes a serving transmission at 10 dB SNR may be able to demodulate and to decode the serving transmission from the data transmission.

In the example ofFIG. 7, the interfering transmission714is from the eNB710a.

However, the UE720may apply the exemplary methods to suppress an interfering transmission from the pico eNB710b. Generally, in the exemplary methods, the UE720may determine an MCS that would facilitate interference suppression of an interfering first cell transmission from a first cell when decoding a second cell transmission from a second cell at the UE720. The interfering first cell transmission is a transmission unintended for the UE720and the second cell transmission is a transmission intended for the UE720. The UE720transmits information indicating the determined MCS for the first cell. The UE720receives a transmission including the second cell transmission from the second cell and the interfering first cell transmission from the first cell. The UE720demodulates the second cell transmission from the received transmission based on the determined MCS. The second cell belongs to the pico eNB710b. The first cell belongs to the eNB710aor the pico eNB710b. When the first cell belongs to the pico eNB710b, the first and second cells may be the same cell, e.g., in a MU-MIMO transmission, or different cells of the pico eNB710b.

FIG. 8is a flow chart800of a method of wireless communication. The method may be performed by a UE, such as the UE720. At step802, the UE determines an SINR associated with reference signals received from a first cell. At step804, the UE determines an MCS that would facilitate interference suppression of an interfering first cell transmission from the first cell when decoding a second cell transmission from a second cell. The interfering first cell transmission is a transmission unintended for the UE. The second cell transmission is a transmission intended for the UE. The interference suppression includes one or more of interference cancelation (e.g., CWIC or SLIC), R-ML decoding in an NAIC context, and other techniques that allow the UE to exploit knowledge of parameters or statistics of the parameters of an interfering first cell transmission. The first cell and the second cell may be the same cell or different cells. When the first and second cells are different cells, they may belong to the same eNB or different eNBs. The UE determines the MCS based on the determined SINR. In one configuration, the UE determines a CQI associated with the determined MCS. The CQI may be one or more of a wideband CQI, a subband CQI for one or more subbands, a most preferred PMI, a least preferred PMI, or a RI. If the UE is performing SLIC, the UE may determine a modulation order that the UE can reliably suppress based on the determined SINR, and determine a highest MCS associated with the determined modulation order. The UE may then determine the MCS to be the highest MCS. If the UE is performing CWIC, the UE may determine the MCS to be an MCS that the UE can reliably suppress based on the SINR.

At step804, the UE may also adjust the determined MCS based on a previously determined MCS and an accuracy of a previous suppression of interference based on the previously determined MCS. If the accuracy of the previous suppression of interference is less than a first threshold (i.e., the previous suppression of interference was inaccurate), the UE may adjust the determined MCS to be lower, and if the accuracy of the previous suppression of interference is greater than a second threshold (i.e., the previous suppression of interference was accurate), the UE may adjust the determined MCS to be higher.

At step804, the UE may determine the MCS further based on a predetermined maximum MCS for the interfering first cell transmission. In such a configuration, the UE may reduce the determined MCS to the predetermined maximum MCS and report the predetermined maximum MCS. In one configuration, the first cell and the second cell may agree on a maximum MCS that can be used by the first cell. In another configuration, the first cell may use an MCS less than or equal to a predetermined maximum MCS for particular subframes/subbands. If the UE determines an MCS that is greater than the predetermined maximum MCS for the particular subframes/subbands, the UE may report the predetermined maximum MCS rather than the determined MCS. Accordingly, the UE may reduce the determined MCS to the predetermined maximum MCS and report the determined reduced MCS.

At step806, the UE transmits information indicating the determined MCS/CQI for the first cell. The UE may transmit the information to the second cell or the first cell. If the UE transmits the information to the second cell, the second cell may aggregate received MCS/CQI information and forward the aggregated information or a portion of the aggregated information to the first cell.

At step808, the UE may receive a downlink grant from the second cell in which the downlink grant is based on the transmitted information indicating the determined MCS for the first cell. As discussed supra, the second cell may schedule UEs that can reliably suppress the interference from the first cell. Specifically, the second cell may schedule the UE for a downlink transmission based on whether the first cell is sending its downlink transmission with an MCS that is less than or equal to the determined MCS. If the first cell is sending its downlink transmission at an MCS less than or equal to a maximum MCS in which the maximum MCS is known to the second cell, the second cell may schedule the UE when the UE reports at step806an MCS that is greater than or equal to the maximum MCS.

At step810, the UE receives a transmission including a second cell transmission from the second cell and an interfering first cell transmission from the first cell. The interfering first cell transmission may be modulated and/or encoded based on the determined MCS for the first cell. Specifically, in a first configuration, the interfering first cell transmission is modulated and/or encoded with the determined MCS for the first cell. In a second configuration, the interfering first cell transmission is modulated and/or encoded with an MCS equal to or lower than the determined MCS. When the interfering first cell transmission is modulated and/or encoded with the MCS indicated at step806, the indicated MCS may be higher than when the interfering first cell transmission is modulated and/or encoded with an MCS less than or equal to the MCS indicated at step806. That is, the UE may indicate a first MCS when the UE knows exactly the MCS that the first cell will use, and may indicate a second MCS less than the first MCS when the UE knows that the first cell will use an MCS less than or equal to indicated MCS.

At step812, the UE determines at least one of subframes or subbands on which the interfering first cell transmission will be modulated and encoded based on the determined MCS. For example, referring toFIG. 7, the UE720may receive information indicating the subframes/subbands from the pico eNB710b. The eNB710aand the pico eNB710bmay agree on the subframes/subbands on which the eNB710awill respect the MCS/CQI report (modulate and/or encode based on the reported MCS/CQI) from the UE.

At step814, the UE determines whether to suppress interference from the received transmission based on whether the transmission is received in the subframes/subbands. If the transmission is received in subframes/subbands on which the interfering first cell transmission is modulated and/or encoded based on the determined MCS, the UE may suppress, from the received transmission, interference to the second cell transmission by the interfering first cell transmission.

The UE may suppress the interference based on knowledge that the interfering first cell transmission is modulated and/or encoded based on the MCS determined and transmitted at steps804,806.

At step816, the UE demodulates and/or decodes the second cell transmission from the received transmission based on an assumption that the interfering first cell transmission is at least one of modulated or encoded based on the determined MCS. At step818, the UE may determine whether the interference suppression was successful. If the interference suppression is determined to be successful, the UE may transmit an ACK. If the interference is determined to be unsuccessful, the UE may transmit a NACK. The UE may transmit the ACK/NACK to either of the first cell or the second cell. If transmitted to the second cell, the second cell may bias the MCS/CQI aggregated reports based on the received ACK/NACK. If transmitted to the first cell, the first cell may bias the MCS based on the received ACK/NACK. Specifically, the first cell may decrease the MCS when a NACK is received and increase the MCS when an ACK is received. In some configurations, the first cell may increase the MCS when an ACK is received only if the MCS was previously decreased based on a received NACK. Accordingly, at804, the UE may determine whether a previous interference suppression was successful. The UE may transmit an ACK when the previous interference suppression is determined to be successful, and transmit a NACK when the previous interference suppression is determined to be unsuccessful. In such a configuration, the interfering first cell transmission from the first cell is modulated and/or encoded based on the determined MCS and based on whether the UE transmits an ACK or a NACK in response to the previous interference suppression.

FIG. 9is a flow chart900of a method of wireless communication. The method may be performed by an eNB, such as the interfering eNB710a. At step902, a cell receives information indicating an MCS that would facilitate interference cancelation by a first UE (e.g., the UE720) of a cell transmission from the cell. At step904, the cell may determine UEs to schedule for receiving a downlink transmission based on the received information indicating the MCS. The determined UEs include a second UE. The cell may determine to utilize the indicated MCS for the downlink transmission or to utilize an MCS less than or equal to the indicated MCS. The cell may determine to schedule the UEs that can reliably decode and demodulate the downlink transmission at the to-be-utilized MCS that the cell determines to utilize for the downlink transmission. UEs that need a lower MCS than the to-be-utilized MCS in order to reliably demodulate/decode the downlink transmission may be scheduled at other times when the cell is not limited by the indicated MCS.

At step906, the cell schedules the second UE to receive a cell transmission based on the determined scheduling. Accordingly, the cell determined that the second UE can reliably demodulated/decode the downlink transmission at the to-be-utilized MCS. The to-be-utilized MCS may be the indicated MCS or an MCS less than or equal to the indicated MCS.

At step908, the cell modulates and/or encodes data based on the received information indicating the MCS. The cell modulates and/or encodes data at the indicated MCS or at an MCS less than or equal to the indicated MCS. At step910, the cell transmits the data in the cell transmission to the second UE.

At step902, the information indicating the received MCS may be received from the first UE or from a second cell serving the first UE. As discussed supra, the cell determines the UEs for receiving the downlink transmission at steps904,906based on whether the UEs are able to receive the downlink transmission at the indicated MCS or an MCS less than or equal to the indicated MCS. The information indicating the MCS may be information indicating a CQI.

At step908, the cell may modulate and/or encode the data with the indicated MCS or with an MCS less than or equal to the indicated MCS. The cell may modulate and/or encode the data with an MCS less than or equal to the indicated MCS when the cell and the second cell agree on a maximum MCS that can be used for the downlink transmission.

FIG. 10is a conceptual data flow diagram1000illustrating the data flow between different modules/means/components in an exemplary apparatus1002. The apparatus may be a UE. The UE includes an MCS/CQI determination module1010that is configured to determine an MCS that would facilitate interference suppression of an interfering first cell transmission from a first cell1060when decoding a second cell transmission from a second cell1050at the UE. The interfering first cell transmission is a transmission unintended for the UE and the second cell transmission is a transmission intended for the UE. The UE further includes a transmission module1014that is configured to transmit information indicating the determined MCS for the first cell1060. The UE further includes a receiving module1004that is configured to receive a transmission including a second cell transmission from a second cell1050and the interfering first cell transmission from the first cell1060. The UE further includes demodulating/decoding module1008that is configured to demodulate and/or to decode the second cell transmission from the received transmission based on an assumption that the interfering first cell transmission is at least one of modulated or encoded based on the determined MCS. The UE may further include an interference suppression module1006that is configured to suppress, from the received transmission, interference to the second cell transmission by the interfering first cell transmission. The interference suppression module1006is configured to suppress the interference based on the determined MCS. The transmission module1014may be configured to transmit the information indicating the determined MCS to one of the second cell1050or the first cell1060. The MCS/CQI determination module1010may be configured to determine a CQI associated with the determined MCS. In such a configuration, the transmission module1014is configured to transmit information indicating the determined CQI. The information indicating the determined CQI may include at least one of a wideband CQI, a subband CQI for one or more subbands, a most preferred PMI, a least preferred PMI, or an RI. The receiving module1004may be configured to receive a downlink grant from the second cell1050. The downlink grant may be based on the transmitted information indicating the determined MCS for the first cell1060. The interfering first cell transmission may be modulated and encoded based on the determined MCS for the first cell1060. The interference suppression module1006may be configured to determine at least one of subframes or subbands on which the interfering first cell transmission will be modulated and encoded based on the determined MCS, and to determine whether to suppress interference from the received transmission based on whether the transmission is received in the at least one of the subframes of the subbands. The interfering first cell transmission may be modulated and encoded with the determined MCS. Alternatively, the interfering first cell transmission may be modulated and encoded with an MCS equal to or lower than the determined MCS. The MCS may be determined based on a predetermined maximum MCS for the interfering first cell transmission. The UE may further include an SINR determination module1012that is configured to determine an SINR associated with reference signals received from the first cell1060. The MCS/CQI determination module1010may be configured to determine the MCS based on the determined SINR. The MCS/CQI determination module1010may be configured to determine a modulation order based on the determined SINR, and to determine a highest MCS associated with the determined modulation order. In such a configuration, the MCS/CQI determination module1010is configured to determine the MCS to be the determined highest MCS. The MCS/CQI determination module1010may be configured to adjust the determined MCS based on a previously determined MCS and an accuracy of a previous suppression of interference based on the previously determined MCS. The demodulating/decoding module1008may be configured to determine whether a previous interference suppression was successful and to inform the transmission module1014whether the demodulating/decoding was successful/unsuccessful. In such a configuration, the transmission module1014may be configured to transmit an ACK when the previous interference suppression is determined to be successful, and to transmit a NACK when the previous interference suppression is determined to be unsuccessful. The interfering first cell transmission from the first cell1060may be modulated and encoded based on the determined MCS and based on whether the UE transmits an ACK or a NACK in response to the previous interference suppression.

FIG. 11is a diagram1300illustrating an example of a hardware implementation for an apparatus1002′ employing a processing system1114. The processing system1114may be implemented with a bus architecture, represented generally by the bus1124. The bus1124may include any number of interconnecting buses and bridges depending on the specific application of the processing system1114and the overall design constraints. The bus1124links together various circuits including one or more processors and/or hardware modules, represented by the processor1104, the modules1004,1006,1008,1010,1012,1014, and the computer-readable medium/memory1106. The bus1124may 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 system1114may be coupled to a transceiver1310. The transceiver1110is coupled to one or more antennas1120. The transceiver1110provides a means for communicating with various other apparatus over a transmission medium. The transceiver1110receives a signal from the one or more antennas1120, extracts information from the received signal, and provides the extracted information to the processing system1114. In addition, the transceiver1110receives information from the processing system1114, and based on the received information, generates a signal to be applied to the one or more antennas1120. The processing system1114includes a processor1104coupled to a computer-readable medium/memory1106. The processor1104is responsible for general processing, including the execution of software stored on the computer-readable medium/memory1106. The software, when executed by the processor1104, causes the processing system1114to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory1106may also be used for storing data that is manipulated by the processor1104when executing software. The processing system further includes at least one of the modules1004,1006,1008,1010,1012,1014. The modules may be software modules running in the processor1104, resident/stored in the computer readable medium/memory1106, one or more hardware modules coupled to the processor1104, or some combination thereof. The processing system1114may 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 apparatus1002/1002′ for wireless communication includes means for determining an MCS that would facilitate interference suppression of an interfering first cell transmission from a first cell when decoding a second cell transmission from a second cell at the UE. The interfering first cell transmission is a transmission unintended for the UE. The second cell transmission is a transmission intended for the UE. The apparatus further includes means for transmitting information indicating the determined MCS for the first cell, means for receiving a transmission comprising the second cell transmission from the second cell and the interfering first cell transmission from the first cell, and means for performing at least one of demodulating or decoding the second cell transmission from the received transmission based on the determined MCS. The means for performing may be configured to demodulate the second cell transmission from the received transmission based on an assumption that the interfering first cell transmission is at least one of modulated or encoded based on the determined MCS. The means for performing may be configured to decode the second cell transmission from the received transmission based on an assumption that the interfering first cell transmission is at least one of modulated or encoded based on the determined MCS. The apparatus may further include means for suppressing, from the received transmission, interference to the second cell transmission by the interfering first cell transmission, the interference being suppressed based on the determined MCS. The apparatus may further include means for determining a CQI associated with the determined MCS. The information indicating the determined MCS may include information indicating the determined CQI. The apparatus may further include means for receiving a downlink grant from the second cell. The downlink grant may be based on the transmitted information indicating the determined MCS for the first cell. In one configuration, the interfering first cell transmission is modulated and encoded based on the determined MCS for the first cell. In such a configuration, the apparatus may further include means for determining at least one of subframes or subbands on which the interfering first cell transmission will be modulated and encoded based on the determined MCS, and means for determining whether to suppress interference from the received transmission based on whether the transmission is received in the at least one of the subframes of the subbands. The apparatus may further include means for determining SINR associated with reference signals received from the first cell. The MCS may be determined based on the determined SINR. The apparatus may further include means for determining a modulation order based on the determined SINR, and means for determining a highest MCS associated with the determined modulation order. The determined MCS may be the determined highest MCS. The apparatus may further include means for adjusting the determined MCS based on a previously determined MCS and an accuracy of a previous suppression of interference based on the previously determined MCS. The apparatus may further include means for determining whether a previous interference suppression was successful, means for transmitting an ACK when the previous interference suppression is determined to be successful, and means for transmitting a NACK when the previous interference suppression is determined to be unsuccessful. The interfering first cell transmission from the first cell may be modulated and encoded based on the determined MCS and on whether the UE transmits an ACK or a NACK in response to the previous interference suppression.

The aforementioned means may be one or more of the aforementioned modules of the apparatus1002and/or the processing system1114of the apparatus1002′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system1114may 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. 12is a conceptual data flow diagram1200illustrating the data flow between different modules/means/components in an exemplary apparatus1202. The apparatus may be an eNB, such as the interfering base station710a. The cell includes a receiving module1210that is configured to receive information indicating an MCS that would facilitate interference suppression by a first UE1250of a cell transmission from the cell. The cell further includes a modulation/encoding module1212that is configured to perform at least one of modulating or encoding data based on the received information indicating the MCS. The cell further includes a transmission module1216that is configured to transmit the data in a cell transmission to a second UE1260. The information indicating the received MCS may be received from the first UE1250or from a second cell serving the first UE1250. The cell may further include a scheduling module1214that is configured to determine UEs to schedule for receiving a downlink transmission based on the received information indicating the MCS. The determined UEs include the second UE1260. The scheduling module1214may be further configured to schedule the second UE1260to receive the cell transmission based on the determined scheduling. The scheduling module1214may be configured to determine the UEs for receiving the downlink transmission based on whether the UEs are able to receive the downlink transmission at the MCS. The information indicating the MCS may be information indicating a CQI. The modulation/encoding module1212may be configured to modulate and/or encode the data with the received MCS or with an MCS less than or equal to the indicated MCS.

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 modules1210,1212,1214,1216, and the computer-readable medium/memory1306. 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 transceiver1310receives a signal from the one or more antennas1320, extracts information from the received signal, and provides the extracted information to the processing system1314. In addition, the transceiver1310receives information from the processing system1314, and based on the received information, generates a signal to be applied to the one or more antennas1320. The processing system1314includes a processor1304coupled to a computer-readable medium/memory1306. The processor1304is responsible for general processing, including the execution of software stored on the computer-readable medium/memory1306. The software, when executed by the processor1304, causes the processing system1314to perform the various functions described supra for any particular apparatus.

The computer-readable medium/memory1306may also be used for storing data that is manipulated by the processor1304when executing software. The processing system further includes at least one of the modules1210,1212,1214,1216. The modules may be software modules running in the processor1304, resident/stored in the computer readable medium/memory1306, one or more hardware modules coupled to the processor1304, or some combination thereof. The processing system1314may 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 apparatus1202/1202′ for wireless communication includes means for receiving information indicating an MCS that would facilitate interference suppression by a first UE of a cell transmission from the cell, means for performing at least one of modulating or encoding data based on the received information indicating the MCS, and means for transmitting the data in the cell transmission to a second UE. The apparatus further include means for determining UEs to schedule for receiving a downlink transmission based on the received information indicating the MCS. The determined UEs include the second UE. The apparatus further includes means for scheduling the second UE to receive the cell transmission based on the determined scheduling.

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 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.