Patent ID: 12232144

DETAILED DESCRIPTION

The present disclosure is directed to a system and method for scheduling and HARQ timing for aggregated TDD CCs with different Up Link/Down Link (UL/DL) configurations. For example, the disclosed systems may include inter-band carrier aggregation where component carriers in each band use different TDD configurations. In these instances, a Primary Cell (PCell) may communicate using a primary component carrier in a first frequency band having a primary TDD configuration, and a Secondary Cell (SCell) communicating using a secondary component carrier in a second frequency band different from the first frequency band having a secondary TDD configuration. In doing so, the mobile device may transmit a downlink HARQ in response to received downlink data in the second component carrier in the primary component carrier using a supplemental TDD configuration. In other words, the mobile device may transmit a downlink HARQ for the second component carrier using a TDD configuration different from the secondary TDD configuration, i.e., a supplemental TDD configuration. In the present disclosure, the term “primary” refers to aspects associated with the PCell such as the primary component carrier refers to a component carrier the PCell communicates. In addition, the term “secondary” refers to aspects associated with the SCell such as the secondary TDD configuration refers to the TDD configuration used by the SCell. In some implementations, the supplemental TDD configuration may be a union or aggregation of the TDD configuration of the PCell and the SCell. For example, the supplemental downlink TDD configuration may be a combination of the primary downlink TDD configuration and the secondary downlink TDD configuration, as discussed in more detail below. In some implementations, the supplemental configuration may be based on the duplex mode of the associated User Equipment (UE) device. For example, the supplemental configuration may be based on whether the UE operates in a full-duplex mode or a half-duplex mode. In addition, the disclosure includes determining the muting direction in the half-duplex mode.

In some implementations in full-duplex mode, the PCell may follow its own timing relationship or the primary TDD configuration for both UL and DL. In these instances, the SCell DL HARQ may follow the timing relationship or the supplemental TDD configuration having the union of DL subframe sets for two aggregated configurations. In some instances, the number of DL HARQ processes may be set to the same number as in the configuration used for DL HARQ timing, which may be the same as one of the seven HARQ timing relationships defined by the LTE standard. The SCell UL grant and UL HARQ may follow the TDD configuration including the union of UL subframe sets for two aggregated configurations. In these instances, the number UL HARQ processes may include the same number as the configuration used for UL timing. In some implementations, the scheme for the full duplex mode may be extended to more than two different configurations in more than two CC CA scenarios. For example, the supplemental downlink TDD configuration may be an aggregation of the primary downlink TDD configuration and all of the secondary downlink TDD configurations. In regards to the TDD configuration for the half-duplex mode, the scheme may be designed to support low cost UEs that do not execute simultaneous Reception/Transmission (RX/TX). To facilitate the timing design, the muting may be limited to the SCell. In some implementations, the timing relationship for the primary cell can be applied to both the primary cell and all secondary cells. In determining the muting direction in the half-duplex mode, the muting may be limited to the SCell due to timing issues. In some implementations, the scheme for the half-duplex mode may update the muting direction semi-statically based on at least one of the interference situation or traffic loading situation. For example, the PCell may be switched to the SCell and the SCell may be switched to PCell.

As previously mentioned, the supplemental TDD configuration in the full-duplex mode may reuse existing timing defined in current LTE system (Rel-Aug. 9, 2010). In other words, the supplemental TDD configuration different from the secondary TDD configuration may be defined such that the result equals one of the seven TDD configurations defined by the LTE standard. For example, the supplemental TDD configuration may be based on a first carrier C1and a second carrier C2having different UL/DL configurations and defined as followed:DL Union (DLU)=DL1∪DL2, where DL1and DL2are the downlink subframe sets of configuration C1and C2.UL Union (ULU)=UL1∪UL2, where UL1and UL2are the uplink subframe sets of configuration C1and C2.PCell follows its own UL/DL configuration or primary TDD configuration. PCell here could be either C1or C2.SCell DL HARQ follows the timing of configuration with the same DL subframe pattern as DLU, which matches one of the seven existing configurations in Table 1.SCell UL grant and UL HARQ follow the timing configuration with the same UL subframe pattern as ULU, which matches one of seven existing configurations in Table 1.

Alternatively, this rule may be defined such that SCell DL HARQ follows the timing configuration including the superset of DL subframes, while SCell UL grant and UL HARQ follow the timing configuration including the superset of UL subframes. The number of DL or UL HARQ processes may be set to the same configuration used for DL or UL HARQ timing, respectively. In this way, the timing linkage for scheduling and HARQ on both CCs may follow the existing timing rules defined in Release Aug. 9, 2010. The above rules may be applicable to both separate scheduling and cross-carrier scheduling cases. By following these implementations, the inter-band TDD CA with different UL/DL configurations may be possible for both high cost UEs, i.e., the UEs capable of supporting simultaneous RX/TX or full-duplex mode, and low cost UEs, i.e., UEs only capable to communication in one direction at a time or half-duplex mode. In half-duplex mode, the muting direction may be semi-statically changed based on the interference condition and traffic situation.

The mobile electronic devices described above may operate in a cellular network, such as the network shown inFIG.1, which is based on the third generation partnership project (3GPP) long term evolution (LTE), also known as Evolved Universal Terrestrial Radio Access (E-UTRA). More specifically,FIG.1is a schematic representation of an example wireless cellular communication system100based on 3GPP long term evolution. The cellular network system100shown inFIG.1includes a plurality of base stations112. In the LTE example ofFIG.1, the base stations are shown as evolved Node B (eNB)112. It will be understood that the base station may operate in any mobile environment including femtocell, picocell, or the base station may operate as a node that can relay signals for other mobile and/or base stations. The example LTE telecommunications environment100ofFIG.1may include one or a plurality of radio access networks110, core networks (CNs)120, and external networks130. In certain implementations, the radio access networks may be Evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access networks (EUTRANS). In addition, in certain instances, core networks120may be evolved packet cores (EPCs). Further, there may be one or more mobile electronic devices102operating within the LTE system100. In some implementations, 2G/3G systems140, e.g., Global System for Mobile communication (GSM), Interim Standard 95 (IS-95), Universal Mobile Telecommunications System (UMTS) and CDMA2000 (Code Division Multiple Access) may also be integrated into the LTE telecommunication system100.

In the example LTE system shown inFIG.1, the EUTRAN110comprises eNB112aand eNB112b. Cell114ais the service area of eNB112aand Cell114bis the service area of eNB112b. UE102aand102boperate in Cell114aand are served by eNB112a. The EUTRAN110can comprise one or a plurality of eNBs112and one or a plurality of UEs can operate in a cell. The eNBs112communicate directly to the UEs102. In some implementations, the eNB112may be in a one-to-many relationship with the UE102, e.g., eNB112ain the example LTE system100can serve multiple UEs102(i.e., UE102aand UE102b) within its coverage area Cell114a, but each of UE102aand UE102bmay be connected only to one eNB112aat a time. In some implementations, the eNB112may be in a many-to-many relationship with the UEs102, e.g., UE102aand UE102bcan be connected to eNB112aand eNB112b. The eNB112amay be connected to eNB112bwith which handover may be conducted if one or both of UE102aand UE102btravels from eNB112ato eNB112b. UE102may be any wireless electronic device used by an end-user to communicate, for example, within the LTE system100. The UE102may be referred to as mobile electronic device, user device, mobile station, subscriber station, or wireless terminal. UE102may be a cellular phone, personal data assistant (PDA), smart phone, laptop, tablet personal computer (PC), pager, portable computer, or other wireless communications device.

UEs102may transmit voice, video, multimedia, text, web content and/or any other user/client-specific content. On the one hand, the transmission of some of these contents, e.g., video and web content, may require high channel throughput to satisfy the end-user demand. On the other hand, the channel between UEs102and eNBs112may be contaminated by multipath fading, due to the multiple signal paths arising from many reflections in the wireless environment. Accordingly, the UEs' transmission may adapt to the wireless environment. In short, UEs102generate requests, send responses or otherwise communicate in different means with Enhanced Packet Core (EPC)120and/or Internet Protocol (IP) networks130through one or more eNBs112.

A radio access network is part of a mobile telecommunication system which implements a radio access technology, such as UMTS, CDMA2000 and 3GPP LTE. In many applications, the Radio Access Network (RAN) included in a LTE telecommunications system100is called an EUTRAN110. The EUTRAN110can be located between UEs102and EPC120. The EUTRAN110includes at least one eNB112. The eNB can be a radio base station that may control all or at least some radio related functions in a fixed part of the system. The at least one eNB112can provide radio interface within their coverage area or a cell for UEs102to communicate. eNBs112may be distributed throughout the cellular network to provide a wide area of coverage. The eNB112directly communicates to one or a plurality of UEs102, other eNBs, and the EPC120.

The eNB112may be the end point of the radio protocols towards the UE102and may relay signals between the radio connection and the connectivity towards the EPC120. In certain implementations, the EPC120is the main component of a core network (CN). The CN can be a backbone network, which may be a central part of the telecommunications system. The EPC120can include a mobility management entity (MME), a serving gateway (SGW), and a packet data network gateway (PGW). The MME may be the main control element in the EPC120responsible for the functionalities comprising the control plane functions related to subscriber and session management. The SGW can serve as a local mobility anchor, such that the packets are routed through this point for intra EUTRAN110mobility and mobility with other legacy 2G/3G systems140. The SGW functions may include the user plane tunnel management and switching. The PGW may provide connectivity to the services domain comprising external networks130, such as the IP networks. The UE102, EUTRAN110, and EPC120are sometimes referred to as the evolved packet system (EPS). It is to be understood that the architectural evolvement of the LTE system100is focused on the EPS. The functional evolution may include both EPS and external networks130.

Though described in terms ofFIG.1, the present disclosure is not limited to such an environment. In general, cellular telecommunication systems may be described as cellular networks made up of a number of radio cells, or cells that are each served by a base station or other fixed transceiver. The cells are used to cover different areas in order to provide radio coverage over an area. Example cellular telecommunication systems include Global System for Mobile Communication (GSM) protocols, Universal Mobile Telecommunications System (UMTS), 3GPP Long Term Evolution (LTE), and others. In addition to cellular telecommunication systems, wireless broadband communication systems may also be suitable for the various implementations described in the present disclosure. Example wireless broadband communication system includes IEEE 802.11 wireless local area network, IEEE 802.16 WiMAX network, etc.

FIG.2is a schematic200illustrating aggregating two CCs with configuration 0 and 1 in accordance with some implementations of the present disclosure. As illustrated, the schematic200includes a timing linkage for c-scheduling with Primary Cell (PCell)202having a configuration 0 and a Secondary Cell (SCell)204having a configuration 1. In these implementations, the downlink subframe union or supplemental downlink TDD configuration and the uplink subframe union or supplemental uplink TDD configuration are defined as followed:DL(conf #0)={0,1,5,6}, DL(conf #1)={0,1,4,5,6,9}; So, DLU={0,1,4,5,6,9}, matches conf #1.UL(conf #0)={2,3,4,7,8,9}, DL(conf #1)={2,3,7,8}; So, ULU={2,3,4,7,8,9}, matches conf #0.

If the PCell202is has configuration 0, the PCell202may follow its own configuration timing. The SCell UL grant and HARQ may also follow configuration 0, and the SCell DL HARQ may follow configuration 1 timing based on the above definition. The schematic200only shows the SCell timing linkage for cross-carrier scheduling case and not the timing linkage for the PCell202as it is the same as in the current specification.

Since the number of UL subframes with SCell configuration 1 is less than the number of UL subframes in configuration 0, the UL index may not be varied in scheduling, and IPHICHmay not be varied in ACK/NACK identification. The UL index value and IPHICHmay be set to a fixed value, e.g., LSB=1, MSB=0 as well as IPHICH=1. Alternatively, the UL index may not be included in the UL grant for SCell's PUSCH scheduling as UL index is used, for example, for UL/DL configuration 0 only. The former approach may keep a DCI format size for SCell's PUSCH the same as the one for PCell's PUSCH which may be desirable for cross-carrier scheduling to share the search space. Not including UL index for the separate scheduling may reduce the DCI format size. Since UL index and Downlink Assignment Index (DAI) share the same two bits in DCI0, collision between these two fields is typically avoided. In some implementations, the UL index may only be used for configuration 0 due to a large number of UL subframes. Any other configurations, except for configuration 6, which use configuration 0 as UL scheduling timing may not use the UL index bits. If there is potential collision with DAI bits, UL index bits may not be included. For configuration 6, the cross-carrier scheduling may be disabled and only use separate scheduling. For SCell subframe #4 and #9, there may be no DL PDCCH at the same TTI to schedule them. For subframe #4 and #9, one or more of the following may be executed: (a) cross TTI scheduling (shown in schematic200, #4 SCell is scheduled by PCell subframe #1); (b) bundle scheduling, e.g. same grant for SCell #4 and #1; (c) temporarily disable cross-carrier scheduling, the SCell #4 and #9 are scheduled by SCell itself; or others.

FIG.3is a schematic300illustrating the SCell timing linkage for separate scheduling case based on one or more implementations in the present disclosure. In particular, the schematic300includes PCell302and SCell304illustrating SCell timing linkage for s-scheduling with PCell configuration 0 and SCell configuration 1. In these implementations, the SCell subframe #0 and #5 may not be configured with any PHICH resource for the UL/DL configuration 1. To be able to transmit ACK/NACK on those subframes, PHICH resource may be configured on those subframes for a new release UE. The legacy UE may not know this newly configured PHICH resource, which may be discarded. The PDCCH blind decoding may not be able to pick it up. Alternatively, only resource adaptive retransmission with UL grant may be supported without PHICH reception for PUSCH in subframe #3 and #8.

Alternatively, the current timing relationship may be reused and the new proposed rule may be applied only in case there is a problem with the current scheduling and HARQ timing. More specifically, for separate scheduling case, the UE may execute a second method including the following: PCell302follows its own UL/DL configuration timing relationship; SCell DL HARQ follows the timing of configuration with the same DL subframe pattern as DLU; and SCell UL grant and UL HARQ follow its own UL/DL configuration timing relationship.

FIG.4is a schematic400illustrating the SCell timing linkage executing the second method previously discussed. In particular, the schematic400includes the PCell402and the SCell404where the SCell UL grant and UL HARQ follow its own UL/DL configuration timing relationship as compared with an UL union. These implementations may not include the zero PHICH resource issue as previously discussed. The UL HARQ cycle may be shorter as well. With carrier aggregation, the load on both PUCCH and PHICH increases. Although the new timing linkage may be used, it may still follow one of the existing UL/DL configurations. In these instances, the current PUCCH and PHICH structure may be supported. For example, for PUCCH, PUCCH format 1b with channel selection may be configured with up to 4 ACK/NACK bits transmission. Otherwise, if the capacity is exceeded, PUCCH format 3 may be used. For PHICH, the amount of PHICH resource may be adjusted by phich-Resource, Ng, in PHICH-Config1E.

FIG.5is a schematic500illustrating SCell timing linkage where the primary cell is configuration 1 and the secondary cell is configuration 0. In particular, the schematic500includes PCell502and SCell504where the SCell timing linkage for c-scheduling with PCell configuration 1 and SCell configuration 2. In these implementations, with cross-carrier scheduling, the SCell UL grant and UL HARQ may follow configuration 0 timing and DL HARQ may follow configuration 1.

FIGS.6-11illustrate schematics600-1100, respectively, for timing linkage in full duplex mode for special cases in regards to UL grant timing and UL HARQ timing. Referring toFIGS.6and7, the schematic600and700illustrate an example with a combination of configuration 2 and configuration 6 where the DLU matches configuration 2 and ULU matches configuration 6. In particular, the schematic600includes PCell602and SCell604where the SCell timing linkage for c-scheduling with PCell configuration 2 and SCell configuration 6, and the schematic700includes the PCell702and the SCell704where SCell timing linkage for c-scheduling with PCell configuration 6 and SCell configuration 2. In other words,FIGS.6and7illustrate the timing linkage for the secondary cell with different primary cell configurations. InFIG.7, when the PCell702is configuration 6, the retransmission for NACK from subframe #1, #6 would be on SCell subframe #8, #3 which is not a UL subframe. The retransmission may be amended to subframe #7, #2. This situation may also apply to the initial UL grant. The similar scenario may occur with a few other configuration combinations as shown below.

Referring toFIGS.8and9, the schematic800and900illustrate an example with a combination of configuration 0 and configuration 2. In particular, the schematic800includes PCell802and SCell804where the SCell timing linkage for c-scheduling with PCell configuration 2 and SCell configuration 0, and the schematic900includes the PCell902and the SCell904where SCell timing linkage for c-scheduling with PCell configuration 0 and SCell configuration 2. With this combination, the SCell UL grant and HARQ follow the configuration 0 timing, and the DL HARQ is following configuration 2. SCell subframe #8 and #3 may not be UL subframes for the UL transmission or retransmission. As shown inFIGS.7and9, the solution may include using (the original subframe index−1) instead. In some implementations, the resulting subframe index for transmission or retransmission cannot be less than n+4, while n is the subframe index conveying the grant or NACK.

Referring toFIGS.10and11, the schematic1000and1100illustrate an example with a combination of configuration 1 and configuration 6. In particular, the schematic1000includes PCell1002and SCell1004where the SCell timing linkage for c-scheduling with PCell configuration 1 and SCell configuration 6, and the schematic1100includes the PCell1102and the SCell1104where the SCell timing linkage for c-scheduling with PCell configuration 6 and SCell configuration 1. Based on the proposed method, the SCell UL grant and HARQ may follow the configuration 6 timing. DL HARQ may follow configuration 1. InFIG.11, subframe #4 may not be an UL, and, if minus one, the subframe #3 may be occupied by the retransmission for NACK from subframe #6. In these instances, the transmission or retransmission may be on the next available UL subframe, which is subframe #7 in this case.

In summary, regardingFIGS.6-11, these special cases may occur when the primary cell DL subframe set is the subset of the secondary cell DL subframe set. In these instances, the following may be executed: the current transmission or retransmission subframe index, m, minus one (m−1) if (m−1) is not less than n+4, while n is the subframe index conveying the grant or NACK; otherwise, or if the m−1 subframe is occupied, transmit or retransmit on the next available UL subframe; and the eNB may have the knowledge of the situation and determine when to expect the transmission or retransmission.

FIGS.12and13are schematics1200and1300, respectively, illustrating timing linkage in full duplex mode with two CCs with different switch periodicities. Two switch periodicities are frequently introduced for compatibility with different chip rate legacy systems. 5 ms switching point periodicity may be introduced to support the coexistence between LTE and low chip rate UTRA TDD systems, and 10 ms switching point periodicity may be for the coexistence between LTE and high chip rate UTRA TDD system. The possibility of aggregating carriers with different switching periodicity configurations may be low, but the methods previously discussed may also work with the different switch periodicity configurations.

Referring toFIG.12, the schematic1200illustrates that PCell1202and SCell1204where the ULU1206is configuration 4 and the DLU1208is configuration 6. Since configuration 1 has two special subframes, one may be identified as a DL subframe. In the instances, the DLU1206is equivalent to configuration 4; while ULU1208is equivalent to configuration 6. The secondary cell UL grant and HARQ may follow configuration 6 timing linkage and DL HARQ may follow configuration 4. Referring toFIG.13, the schematic1300includes PCell1302and the SCell1304where SCell timing linkage for c-scheduling with PCell configuration 3 and SCell configuration 1. In particular, the schematic1300illustrates the secondary cell timing linkage with configuration 3 as the primary cell and configuration 1 as the secondary cell in the case of cross-carrier scheduling.

In addition toFIGS.2-13, the time linkage in the full duplex mode may be extend to more than two different configurations. For example, in the case with five different UL/DL configurations, CPand CS1, CS2, CS3, CS4, on different CCs may be aggregated together. CPmay be the primary cell and CSii=1,2,3,4, may be the secondary cells. The timing linkage or supplemental TDD configuration may be defined as followed: (1) DLUi=DLP∪DLSi, where DLPand DLSiare the downlink subframe sets of configuration CPand CSi, i=1,2,3,4; (2) ULUi=ULP∪ULSi, where ULPand ULSiare the uplink subframe sets of configuration CPand CSi, i=1,2,3,4; (3) PCell follows its own UL/DL configuration timing relationship; (4) SCell with CSi, i=1,2,3,4, DL HARQ follows the timing of configuration with the same DL subframe pattern as DLUi; and (5) SCell with CSi, i=1,2,3,4, UL grant and UL HARQ follow the timing of configuration with the same UL subframe pattern as ULUi. For separate scheduling case, the second method previously discussed may be also applied as followed: (1) PCell follows its own UL/DL configuration timing relationship; (2) SCell with CSi, i=1,2,3,4, DL HARQ follows the timing of configuration with the same DL subframe pattern as DLUi; and (3) SCell with CSi, i=1,2,3,4, UL grant and UL HARQ follow its own UL/DL configuration, CSi, timing relationship.

FIGS.14-17are schematics1400-1700, respectively, that illustrate carrier aggregation in half-duplex mode. These implementations are designed for the low cost UE which does not support simultaneous RX/TX. To facilitate the timing design, the muting may occur on the SCell because the PUCCH may be on the primary cell and grants may come from the PCell as well if cross-carrier scheduling. The flexibility of radio subframe allocation is implemented by the approach described with respect toFIG.17.

For half duplex capable UEs, CCs with different switch periodicity UL/DL configurations are typically not aggregated because the number of special subframes is different with different switch periodicities. Referring toFIG.14, the schematic1400illustrates CA between configuration 0 and configuration 5. In particular, the schematic1400includes the cell1402and the cell1404such that subframe #6 is muted, which may lead to low resource utilization efficiency. To address this inefficiency, UEs operating in a half-duplex mode may execute one or more of the following: (1) do not consider CA with different switch periodicity configurations; (2) during conflicting subframes, execute the PCell subframe direction; use the PCell timing on all CCs; and the few exception cases are handled with the same method as in full duplex case.

Referring toFIGS.15and16, the schematics1500and1600illustrate the situation where configuration 2 and configuration 6 are aggregated with half duplex mode. In these implementations, the subframes in boxes are muted. Referring toFIG.15, the schematic1500includes PCell1502and SCell1504illustrating SCell timing linkage for c-scheduling with PCell configuration 2 and SCell configuration 6. In other words, the PCell1502is configuration 2, so the timing relationship follows configuration 2 timing. Referring toFIG.16, the schematic1600includes PCell1602and SCell1604illustrating SCell timing linkage for c-scheduling with PCell configuration 6 and SCell configuration 2. The PCell16-2is configuration 6, so the timing linkage follows configuration 6. In this case, the exception case appears on PCell subframes #3 and #8, so the minus one rule previously described may be applied in these instances. The implementations described inFIGS.14-17may be applied to both cross-carrier scheduling and separate scheduling scenarios.

In regards to determining the muting direction in the half-duplex mode, the muting, in some implementations, can occur on the SCell due to the timing issue. In these instances, the muting direction may be semi-statically based on at least one of the interference situation or traffic intensity. For example, the PCell and SCell may be switched.

Referring toFIG.17, the schematic1700illustrates CA with configuration 0 and 1 in half duplex mode. In particular, the schematic1700includes the cell1702and the cell1704illustrating a combination of configuration 0 and 1 where the direction conflicting subframes are #4 and #9. In half duplex mode, schematic1700illustrates that one direction subframe is muted from both the cell1702and the cell1704. The determination of the muting direction may be based on the evaluation of current interference condition (interference at least one of a certain band, time period or UL/DL direction) and traffic situation (UL or DL heavy). If the decision is to mute the DL direction, then the cell1702may be taken as the primary cell, all the timing relationship follows the configuration 0 timing, subframes #4 and #9 on configuration 1 may be muted and vice versa. This process may be performed periodically and the muting direction may be semi-statically changed. In some implementations, the UE may switch the PCell and SCell, in order to change the muting direction, executing the following: (1) for given period, evaluate the interference condition and traffic situation; (2) if the muting direction need to be changed, (a) handover from current PCell to deactivated SCell, (b) remove the current SCell in the SCell list, and (c) add the current PCell as a SCell; and (3) return to the initial step.

FIGS.18and19are flowcharts illustrating example methods for HARQ timing for CCs with different UL/DL configurations for a full-duplex mode and a half-duplex mode, respectively. These methods are for illustration purposes only and that the described or similar techniques may be performed at any appropriate time, including concurrently, individually, or in combination. In addition, many of the steps in the flowchart may take place simultaneously and/or in different orders than as shown. Moreover, systems may use methods with additional steps, fewer steps, and/or different steps, so long as the methods remain appropriate.

Referring toFIG.18, method1800begins at step1802where, using a primary Time Division Duplex (TDD) configuration, data is received on a primary component carrier in a first frequency band. For example, the PCell may communicate downlink data to a UE using a primary component carrier in a first frequency band in accordance with a primary TDD configuration. As previously mentioned, the downlink TDD configuration for a PCell may be referred to as a primary downlink TDD configuration. At step1804, using a secondary TDD configuration, data is received on a secondary component carrier in a second frequency band different from the first frequency band. In the example, the SCell may communicate with the UE using a secondary component carrier in a second frequency band different from the first frequency band. Similar to the PCell, the downlink TDD configuration for the SCell may be referred to the secondary downlink TDD configuration. Next, at step1806, a Hybrid Automatic Repeat Request (HARQ) for data received on the second component carrier is transmitted using a supplemental DL TDD configuration. As for the example, the UE may transmit a downlink HARQ using a supplemental TDD configuration different from the secondary TDD configuration. In some implementations, the supplemental TDD configuration may be an aggregation of the primary TDD configuration and the secondary TDD configuration. At step1808, using a supplemental uplink TDD configuration, an uplink HARQ for uplink data transmitted on the secondary component carrier is received. In some implementations, the supplemental uplink TDD configuration specifies a set of uplink subframes including uplink subframes in the primary TDD configuration and the secondary TDD configuration. Next, at step1810, using the supplemental uplink TDD configuration, an uplink grant granting resources for uplink data transmissions is received on the secondary component carrier.

Referring toFIG.19, method1900begins at step1902where a first transmission direction at a subframe in a primary component carrier is determined using a primary Time Division Duplex (TDD) configuration. In some implementations, the primary component carrier is in a first frequency band. Next, at step1904, second transmission direction at the subframe in a secondary component carrier is determined using a secondary TDD configuration. In some implementations, the second component carrier is in a second frequency band different from the first frequency band. At step1906, a muted component carrier is selected from component carriers based on interference situation and traffic scenario. Next, at step1908, transmission and reception on the muted component carrier is muted at the subframe.

A number of implementations of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.