Patent Description:
Long term evolution-advanced (LTE-A, Long Term Evolution-Advanced) is a system further evolved and enhanced from a 3GPP LTE system. In the LTE-A system, a carrier aggregation (CA, Carrier Aggregation) technology is introduced to satisfy the requirement of the International Telecommunication Union for the peak data rate of the fourth generation communications technology. The carrier aggregation technology is also referred to as a spectrum aggregation (Spectrum Aggregation) technology or a bandwidth extension (Bandwidth Extension) technology.

In carrier aggregation, spectrums of two or more component carriers (Component Carriers) are aggregated to form an aggregated carrier to obtain a wider transmission bandwidth. Spectrums of component carriers in the aggregated carrier may be contiguous continuous spectrums, or may be non-contiguous spectrums in a same frequency band or even discontinuous spectrums in different frequency bands. For the aggregated carrier, an LTE Rel-<NUM>/<NUM> user equipment (UE) can access only one of component carriers to transmit and receive data, but an LTE-A UE can access multiple component carriers simultaneously according to its own capability and service requirement to transmit and receive data.

In the carrier aggregation, to support technologies such as dynamic scheduling, downlink multiple input multiple output (MIMO, Multiple Input Multiple Output) transmission, and hybrid automatic repeat request, the UE needs to feed back multiple types of uplink control information (UCI, Uplink Control Information) to a base station through a physical uplink control channel (PUCCH), where the UCI includes channel state information (CSI, Channel State Information), a HARQ-ACK, a scheduling request (SR, Scheduling Request), and so on, where the HARQ-ACK may also be simply referred to as an ACK (Acknowledgment, acknowledgement information)/NACK (Negative Acknowledgement, negative acknowledgement information) and the SR is used by the UE to request resources for uplink data sending from the base station.

In the prior art, during carrier aggregation, carriers in a macro base station and a micro base station that have an ideal backhaul (Backhaul) may be aggregated. For example, if the macro base station and micro base station are connected through optical fibers, where the micro base station is implemented by using a radio head and an ideal backhaul exists between the macro base station and the micro base station, data may be transmitted between the macro base station and the micro base station in real time. Multiple carries in the macro base station and micro base station may be scheduled jointly, that is, the macro base station also knows the scheduling condition on another component carrier when scheduling one component carrier in the aggregated carrier. In this case, when the UE feeds back a HARQ-ACK to the micro base station, generally the UE sends the HARQ-ACK to the macro base station through a PUCCH on an uplink primary carrier corresponding to the macro base station, and then the macro base station forwards the HARQ-ACK to the micro base station. Because an ideal backhaul exists between the macro base station and the micro base station, both the macro base station and the micro base station can obtain in real time the HARQ-ACK fed back by the UE.

With the continuous development of technologies, carrier aggregation between base stations having a non-ideal backhaul will be introduced in the LTE-A system, where the base stations having a non-ideal backhaul may be two macro base stations, or a macro base station and a micro base station, or two micro base stations, and so on. At present, the prior art has not disclosed a method for transmitting a HARQ-ACK between a UE and a base station in a case where carrier aggregation is performed between base stations having a non-ideal backhaul.

<CIT> discloses a method and device for transmitting reception confirmation in a wireless communication system. In the method, a user equipment receives uplink-downlink (UL-DL) configuration information on a plurality of subframes. The user equipment receives data in at least one subframe among the plurality of subframes; and the user equipment transmits the ACK/NACK through a UL subnframe, wherein each of the plurality of subframes is any one of a flexible subframe and a default DL subframe fixed to a DL subframe, and the flexible subframe is a subframe that can be configured as a UL subfame or a DL subframe by the UL-DL configuration information, and wherein an ACK/NACK payload size indicates an information bit size of the ACK/NACK is determined on the basis of the number of default DL subframes, the number of flexible subframes, and a transmission mode of the plurality of subframes.

<CIT> discloses a method for sending acknowledgement information and user equipment. The user equipment obtains the ACK/NACK acknowledgement information bit sequence as follows: the UE determines the ACK/NACK acknowledgement information according to the number of downlink component carriers configured by the base station, a transmission mode of each downlink component carrier, uplink to downlink subframe ratio, and the number of the at most ACK/NACK acknowledgement information that can be sent by a PUSCH.

Embodiments of the present invention provide a method, an apparatus, a UE, and a base station for transmitting a HARQ-ACK, which can implement transmission of a HARQ-ACK between a UE and a base station in a scenario where carrier aggregation is performed between base stations having a non-ideal backhaul.

To describe the technical solutions in the embodiments of the present invention or in the prior art more clearly, the following briefly introduces the accompanying drawings required for describing the embodiments or the prior art.

If carrier aggregation between base stations having a non-ideal backhaul is introduced in an LTE-A system, no method for transmitting a HARQ-ACK between a UE and a base station exists in the prior art. Therefore, the embodiments of the present invention provide a method, an apparatus, a UE, and a base station for transmitting a HARQ-ACK, which can implement transmission of a HARQ-ACK between a UE and a base station in a scenario where carrier aggregation is performed between base stations having a non-ideal backhaul.

Further, only carrier aggregation between a macro base station and a micro base station that have an ideal backhaul exists in the prior art.

In a scenario where carrier aggregation is performed between a macro base station and a micro base station that have an ideal backhaul, when the UE needs to feed back a HARQ-ACK to the micro base station, the UE sends the HARQ-ACK to the macro base station, and then the macro base station forwards the HARQ-ACK to the micro base station. Because an ideal backhaul exists between the macro base station and the micro base station, both the macro base station and the micro base station can obtain in real time the HARQ-ACK fed back by the UE.

However, if the method is used in a scenario where carrier aggregation is performed between the macro base station and the micro base station that have a non-ideal backhaul, because a non-ideal backhaul exists between the macro base station and the micro base station, data cannot be transmitted in real time, and the macro base station cannot transmit the HARQ-ACK to the micro base station in real time. Therefore, receiving, by the micro base station, the HARQ-ACK fed back by the UE is delayed, and further, scheduling of downlink data by the micro base station for the UE is delayed.

The method, the apparatus, the UE, and the base station for transmitting a HARQ-ACK in the embodiments of the present invention, in comparison with the scenario of the present invention using the method for transmitting uplink control information in the scenario where carrier aggregation is performed between the macro base station and the micro base station that have an ideal backhaul in the prior art, can reduce the delay in obtaining the HARQ-ACK by the micro base station and reduce time of performing downlink data scheduling by the micro base station for the UE.

In addition, it should be noted that the method for transmitting a HARQ-ACK in the embodiments of the present invention may be applied to a scenario where carrier aggregation is performed between n base stations having a non-ideal backhaul, where n is an integer not less than <NUM>. A base station in the n base stations may be a macro base station or a micro base station and so on.

The current subframe in the embodiments of the present invention is a subframe for transmitting the HARQ-ACK. The base station is a base station in the scenario where carrier aggregation is performed between the n base stations having a non-ideal backhaul, that is, any base station in the n base stations. The UE is a UE that needs to send the HARQ-ACK to the n base stations in the scenario where carrier aggregation is performed between the n base stations having a non-ideal backhaul.

The description about whether a PUCCH is transmitted in a carrier in the embodiments of the present invention is a simplified description about whether data transmission through the PUCCH exists in the carrier, and is a description well known by a person skilled in the art. Other descriptions about PUCCH transmission or transmission of the PUCCH in the embodiments of the present invention are similar to the above. Other descriptions about a PUSCH in the embodiments of the present invention are also similar to the above and are not further described in detail.

In order that a person skilled in the art better understand the technical solutions of the embodiments of the present invention, and in order to make the above objective, features, and advantages of the embodiments of the present invention more comprehensible, the technical solutions of the embodiments of the present invention are hereinafter described in detail with reference to the accompanying drawings.

<FIG> is a flowchart of an embodiment of a method for transmitting a HARQ-ACK according to the present invention, where the method may be applied to a UE. As shown in <FIG>, the method includes:
Step <NUM>: Determine a channel for transmitting a HARQ-ACK.

When it is determined that the channel for transmitting the HARQ-ACK is a PUCCH, the uplink carrier where the PUCCH is located and the base station corresponding to the uplink carrier may be determined according to a specific condition in an actual application.

For example, assuming that an uplink primary carrier in the carrier aggregation scenario is designated beforehand in uplink carriers corresponding to the n base stations performing carrier aggregation, when it is determined that the channel for transmitting the HARQ-ACK is a PUCCH, the PUCCH may be a PUCCH in the uplink primary carrier in the carrier aggregation scenario. For example, if uplink carrier B corresponding to base station A in the n base stations is designated as an uplink primary carrier in the carrier aggregation scenario, the PUCCH may be a PUCCH in uplink carrier B corresponding to base station A.

Alternatively, if no uplink primary carrier in the carrier aggregation scenario is designated, but for each base station in the n base stations, an uplink primary carrier corresponding to the base station is designated, when it is determined that the channel for transmitting the HARQ-ACK is a PUCCH, the PUCCH may be a PUCCH in the uplink primary carrier corresponding to the base station accessed by the UE.

Step <NUM>: Determine a HARQ-ACK feedback bit.

The execution sequence of step <NUM> and step <NUM> is not limited.

The HARQ-ACK feedback bit refer to:
Preferably, the determining a HARQ-ACK feedback bit may include:.

The HARQ-ACK timing of each carrier is:
when at least one carrier uses an FDD manner and at least one carrier uses a TDD manner in carriers for carrier aggregation, if detecting, in subframe n, a PDSCH or a PDCCH indicating semi-persistent scheduling release in the carrier that uses the TDD manner, the UE shall determine to feed back a HARQ-ACK in subframe n+<NUM>, where the HARQ-ACK fed back in subframe n+<NUM> is a HARQ-ACK corresponding to the PDSCH or the PDCCH indicating semi-persistent scheduling release which is detected in subframe n.

When all carriers for carrier aggregation use the FDD manner or the TDD manner, determining transmission time of the HARQ-ACK may be implemented with reference to the description in an existing standard. For example, when all carriers corresponding to a first base station and a second base station use the FDD manner, the HARQ-ACK corresponding to the PDSCH or the PDCCH indicating semi-persistent scheduling release which is received in subframe n is fed back in subframe n+<NUM>.

The downlink subframe corresponding to the current subframe means that the HARQ-ACK of the downlink subframe is fed back in the current subframe.

Preferably, the determining the HARQ-ACK feedback bit based on the number of downlink subframes corresponding to the current subframe for each carrier may include:.

Step <NUM>: Send the HARQ-ACK feedback bit on the channel.

Preferably, when the determined channel for sending the HARQ-ACK in step <NUM> is a PUCCH, the transmitting the HARQ-ACK through the channel may include:.

When a channel format of the PUCCH is format <NUM>, and when the current subframe is configured to transmit a scheduling request, the determining a PUCCH resource for transmitting the HARQ-ACK may be implemented in at least two manners:.

In the first implementation manner, a higher layer may reserve a PUCCH resource for each base station; in this case, the determining a PUCCH resource for transmitting the HARQ-ACK may include:
reserving a PUCCH resource for each base station; and determining, according to a base station corresponding to the scheduling request that the current subframe is configured to transmit, the PUCCH resource reserved for the base station as the PUCCH resource for transmitting the HARQ-ACK.

In the second implementation manner, a higher layer reserves a PUCCH resource for all base stations; for different base stations, cyclic shifts of reference signals in the reserved PUCCH resource are different, so as to distinguish the difference of the base stations that use the PUCCH resource to transmit data. In this case, the determining a PUCCH resource for transmitting the HARQ-ACK may include:
reserving a PUCCH resource; determining a PUCCH resource index, and obtaining a sequence index of an orthogonal sequence of the PUCCH according to the resource index; determining, according to the sequence index, a cyclic shift of a reference signal; and determining the reserved PUCCH resource that uses the cyclic shift, as the PUCCH resource for transmitting the HARQ-ACK.

Preferably, the determining, according to the sequence index, a cyclic shift of a reference signal includes:.

When a channel format of the PUCCH is format 1b, and when the current subframe is configured to transmit a scheduling request, the determining a PUCCH resource for transmitting the HARQ-ACK includes:
reserving a PUCCH resource for each base station; and determining, according to a base station corresponding to the scheduling request that the subframe transmitting the acknowledgement information is configured to transmit, the PUCCH resource reserved for the base station as the PUCCH resource for transmitting the HARQ-ACK.

How the UE sends, at the transmission time, the HARQ-ACK by using the PUCCH resource is not further described herein.

The higher layer may be a base station or an upper layer of the base station.

In the method for transmitting a HARQ-ACK shown in <FIG>, a UE determines a channel for transmitting a HARQ-ACK and determines a HARQ-ACK feedback bit, and sends the HARQ-ACK feedback bit on the channel. Therefore, the UE can send the HARQ-ACK to a base station.

<FIG> is a flowchart of another embodiment of a method for transmitting a HARQ-ACK according to the present invention. The method may be applied to a base station, where the base station is any base station in the n base stations; the base station may be a macro base station or a micro base station and so on. As shown in <FIG>, the method includes:
Step <NUM>: Determine a channel used by a UE for transmitting a HARQ-ACK.

Preferably, the determining a channel used by a UE for transmitting a HARQ-ACK may include:.

The PUSCH determined in this step is a PUSCH in an uplink carrier corresponding to the base station.

The method for the base station to determine the channel used by the UE for transmitting the HARQ-ACK should correspond to the method for the UE to determine the channel for transmitting the HARQ-ACK in step <NUM>. Therefore, the UE and the base station can respectively send and detect the HARQ-ACK through the corresponding channel in the corresponding carrier, thereby implementing the transmission of the HARQ-ACK between the UE and the base station. Therefore, in this step, when the base station determines that the channel used by the UE for transmitting the HARQ-ACK is a PUCCH, specifically, for which uplink carrier the PUCCH channel should be located in, reference may be made to the related description of determining the PUCCH by the UE in step <NUM>, and the determining in this step needs to correspond to the policy of determining a PUCCH by the UE in step <NUM>.

For example, if the determined channel used by the UE for transmitting the HARQ-ACK is a PUCCH in an uplink primary carrier in the carrier aggregation scenario, when the base station determines, in this step, that the channel for transmitting the HARQ-ACK is a PUCCH, the PUCCH should also be the PUCCH in the uplink primary carrier in the carrier aggregation scenario.

If the determined channel used by the UE for transmitting the HARQ-ACK is a PUCCH in an uplink primary carrier corresponding to the base station accessed by the UE, when the base station determines, in this step, that the channel for transmitting the HARQ-ACK is a PUCCH, the PUCCH should also be the PUCCH in the uplink primary carrier corresponding to the base station accessed by the UE.

Step <NUM>: Determine the number of bits of the HARQ-ACK transmitted by the UE.

Preferably, the determining the number of bits of the HARQ-ACK transmitted by the UE includes:.

The HARQ-ACK timing of each carrier is:
when at least one carrier uses an FDD manner and at least one carrier uses a TDD manner in carriers for carrier aggregation for the user equipment, if detecting, in subframe n, a PDSCH or a PDCCH indicating semi-persistent scheduling release in the carrier that uses the TDD manner, the UE shall determine to feed back a HARQ-ACK in subframe n+<NUM>. The HARQ-ACK fed back in subframe n+<NUM> should be a HARQ-ACK corresponding to the PDSCH or the PDCCH indicating semi-persistent scheduling release which is scheduled for the UE in subframe n.

The determining the number of bits of the HARQ-ACK based on the number of downlink subframes corresponding to the current subframe for each carrier may include:.

For the case of determining, in step <NUM>, that the channel for transmitting the HARQ-ACK is a PUCCH and a PUSCH, the number of bits corresponding to the PUCCH and PUSCH needs to be determined respectively according to the method for determining the number of bits described in (<NUM>) and (<NUM>). Specifically, for the determined PUCCH, the number of bits of the acknowledgement information is determined according to the method corresponding to the PUCCH in (<NUM>); for the determined PUSCH, the number of bits of the acknowledgement information is determined according to the method corresponding to the PUSCH in (<NUM>).

The specific implementation method for determining the number of bits of the HARQ-ACK is exemplified as follows:.

The number of bits of the HARQ-ACK is determined through the following formula: OACK = Nsubframe ·(C+C<NUM>), where, OACK is the number of bits of the HARQ-ACK, Nsubframe is the number of downlink subframes corresponding to the current subframe, C is the number of configured carriers, and C<NUM> is the number of carriers where a configured transmission mode may support dual-codeword transmission. When all carriers using the TDD manner use timing of hybrid automatic repeat request-acknowledgement information in the FDD manner, Nsubframe=<NUM>.

Step <NUM>: Detect the HARQ-ACK on the channel according to the number of bits.

Assuming that it is determined, in step <NUM>, that the channel used by the UE for transmitting the HARQ-ACK is a PUCCH, the HARQ-ACK only needs to be detected directly on the PUCCH in this step.

Assuming that it is determined, in step <NUM>, that the channel used by the UE for transmitting the HARQ-ACK is a PUCCH and a PUSCH, and when the PUCCH has a higher priority than the PUSCH, the detecting the HARQ-ACK on the channel may include:.

Preferably, assuming that it is determined, in step <NUM>, that the channel used by the UE for transmitting the HARQ-ACK is a PUCCH, or when the HARQ-ACK is first detected on the PUCCH in this step, the detecting the HARQ-ACK on the PUCCH may include:.

In addition, apart from detecting the HARQ-ACK on the PUCCH resource, the method may further include:
detecting scheduling request information on the PUCCH resource, and determining, according to the determined PUCCH resource, a base station corresponding to the scheduling request information request, where the base station corresponding to the scheduling request is a base station from which an uplink resource is requested by the scheduling request.

The determining a PUCCH resource used by the UE for transmitting the HARQ-ACK may include:.

The PUCCH resource is a resource semi-statically reserved by the base station for the user equipment, and the base station transmits information indicating the semi-statically reserved PUCCH resource to another base station through an X2 interface.

With reference to the description in step <NUM>, the higher layer may reserve a PUCCH resource for each base station; or the higher layer may also reserve a PUCCH resource for all base stations. However, for different base stations, cyclic shifts of reference signals in the reserved PUCCH resource may be different to distinguish the difference of base stations that use the PUCCH resource to transmit data. The reserved information may be stored in each base station, or may also be stored in a base station and transmitted between base stations through an X2 interface between the base stations.

In the method for transmitting a HARQ-ACK shown in <FIG>, a base station determines a channel used by a UE for transmitting a HARQ-ACK, determines the number of bits and transmission time of the HARQ-ACK, and detects the HARQ-ACK on the channel according to the number of bits and the transmission time. Therefore, a base station can detect the HARQ-ACK.

<FIG> is a flowchart of another embodiment of a method for transmitting a HARQ-ACK according to the present invention. This embodiment is described with reference to a specific application instance.

The embodiment shown in <FIG> is applicable to a scenario where carrier aggregation is performed between two base stations having a non-ideal backhaul. In this embodiment, the two base stations are respectively described as a first base station and a second base station. The two base stations may be both macro base stations or both micro base stations, or, one is a macro base station and the other is a micro base station, which is not limited herein.

As shown in <FIG>, the method for transmitting a HARQ-ACK in the embodiment of the present invention includes:
Step <NUM>: A UE determines a channel for transmitting a HARQ-ACK.

The implementation of this step may include:.

The related description about the implementation of the above step is given in step <NUM>, and is not further described herein. Here the case described in <NUM> is described in more detail.

Preferably, the determining, according to whether the UE detects that a PDSCH and/or a PDCCH indicating semi-persistent scheduling release is transmitted in downlink carriers corresponding to the first base station and second base station and whether PUSCHs are transmitted in uplink carriers corresponding to the first base station and second base station, the channel for transmitting the HARQ-ACK may include:.

The determining, according to a first preset manner, the channel for transmitting the HARQ-ACK may include:.

The preset priority condition may be: a HARQ-ACK transmission priority of each base station; and therefore, the determining, according to a preset priority condition, the channel for transmitting the HARQ-ACK may include:
determining, according to the HARQ-ACK transmission priority of each base station, that the channel for transmitting the HARQ-ACK is a PUSCH transmitted in an uplink carrier corresponding to a base station of a higher transmission priority.

For example, when the priority condition is preset, the HARQ-ACK transmission priority of the first base station may be preset to be higher than the HARQ-ACK transmission priority of the second base station, for example, the HARQ-ACK transmission priority of the first base station is set to be high, and the HARQ-ACK transmission priority of the second base station is set to be low, then the channel for transmitting the HARQ-ACK may be determined as: the PUSCH transmitted in the uplink carrier corresponding to the first base station.

Alternatively, the preset priority condition may be: a priority of a PUSCH transmitted in an uplink carrier corresponding to each base station; and therefore, the determining, according to a preset priority condition, the channel for transmitting the HARQ-ACK includes:
determining, according to the priorities of PUSCHs, that the channel for transmitting the HARQ-ACK is a PUSCH of a higher priority.

For example, when the priority condition is preset, the priority of the PUSCH transmitted in the uplink carrier corresponding to the first base station may be set to be higher than the priority of the PUSCH transmitted in the uplink carrier corresponding to the second base station, for example, the priority of the PUSCH transmitted in the uplink carrier corresponding to the first base station is set to be high, and the priority of the PUSCH transmitted in the uplink carrier corresponding to the second base station is set to be low, then the channel for transmitting the HARQ-ACK may be determined as: the PUSCH transmitted in the uplink carrier corresponding to the first base station.

When the UE detects that a PDSCH and/or a PDCCH indicating semi-persistent scheduling release is transmitted in a downlink carrier corresponding to the first base station, and the UE detects that a PDSCH and/or a PDCCH indicating semi-persistent scheduling release is transmitted in a downlink carrier corresponding to the second base station, and a PUSCH is transmitted in an uplink carrier corresponding to only the first base station or the second base station in the current subframe, determine, according to a second preset manner, the channel for transmitting the HARQ-ACK.

The determining, according to a second preset manner, the channel for transmitting the HARQ-ACK may include:.

When the UE only detects that a PDSCH and/or a PDCCH indicating semi-persistent scheduling release is transmitted in a downlink carrier corresponding to the first base station, and a PUSCH is transmitted in an uplink carrier corresponding to only the second base station in the current subframe, determine that the channel for transmitting the HARQ-ACK is a PUCCH.

In this case, the PUSCH transmitted in the uplink carrier corresponding to the second base station is discarded.

When the UE only detects that a PDSCH and/or a PDCCH indicating semi-persistent scheduling release is transmitted in a downlink carrier corresponding to the second base station, and a PUSCH is transmitted in an uplink carrier corresponding to only the first base station in the current subframe, determine that the channel for transmitting the HARQ-ACK is a PUCCH;.

In this case, the PUSCH transmitted in the uplink carrier corresponding to the first base station is discarded.

Step <NUM>: The UE determines, according to HARQ-ACK timing of each carrier, the number of downlink subframes corresponding to the current subframe for each carrier.

Step <NUM>: Determine a HARQ-ACK feedback bit based on the number of downlink subframes corresponding to the current subframe for each carrier.

When it is determined, in step <NUM>, that the channel for transmitting the HARQ-ACK is a PUCCH, the HARQ-ACK feedback bit may be determined based on the number of carriers configured for the UE, a transmission mode of each carrier, and the number of downlink subframes corresponding to the current subframe for each carrier; and
when it is determined, in step <NUM>, that the channel for transmitting the HARQ-ACK is a PUSCH, the HARQ-ACK feedback bit may be determined based on a first configured carrier set, a transmission mode of each carrier in the first configured carrier set, and the number of downlink subframes corresponding to the current subframe for each carrier, where the first configured carrier set includes all downlink carriers corresponding to the PUSCH in downlink carriers configured for the UE, where the downlink carriers corresponding to the PUSCH are downlink carriers corresponding to a base station corresponding to the PUSCH.

Preferably, when the determined channel for transmitting the HARQ-ACK in step <NUM> is a PUCCH, the sending the HARQ-ACK feedback bit on the channel may include:.

When a channel format of the PUCCH is format <NUM>, and when the current subframe is configured to transmit a scheduling request, the determining a PUCCH resource for transmitting the HARQ-ACK may include:.

The determining, according to the sequence index, a cyclic shift of a reference signal may include:.

When a channel format of the PUCCH is format 1b, and when the current subframe is configured to transmit a scheduling request, the determining a PUCCH resource for transmitting the HARQ-ACK includes:
reserving a PUCCH resource for the first base station and the second base station respectively; and determining, according to a base station corresponding to the scheduling request that the subframe transmitting the acknowledgement information is configured to transmit, the PUCCH resource reserved for the base station as the PUCCH resource for transmitting the HARQ-ACK.

When the UE determines, in step <NUM>, that the channel for transmitting the HARQ-ACK is a PUSCH, the transmission at the transmission time may be implemented with reference to the method described in an existing standard and is not further described herein.

Step <NUM>: The second base station determines the channel used by the UE for transmitting the HARQ-ACK.

Preferably, the determining, by the second base station, the channel used by the UE for transmitting the HARQ-ACK may include:.

Step <NUM>: The second base station determines, according to HARQ-ACK timing of each carrier, the number of downlink subframes corresponding to the current subframe for each carrier.

Step <NUM>: The second base station determines the number of bits of the HARQ-ACK based on the number of downlink subframes corresponding to the current subframe for each carrier.

Preferably, the determining, by the second base station, the number of bits of the HARQ-ACK based on the number of downlink subframes corresponding to the current subframe for each carrier may include:.

Step <NUM>: The second base station detects the HARQ-ACK on the determined channel according to the number of bits.

When the channel determined by the second base station in step <NUM> is a PUCCH, the second base station detects the HARQ-ACK on the PUCCH in this step.

When the channel determined by the second base station in step <NUM> is a PUCCH and a PUSCH in the uplink carrier corresponding to the second base station, the detecting the HARQ-ACK on the determined channel may include:.

The detecting the HARQ-ACK on the PUCCH may include:.

The determining a PUCCH resource used by the UE for transmitting the HARQ-ACK includes:.

The PUCCH resource reserved for each base station may be stored in each base station, or may also be stored in a base station and transmitted between base stations through an X2 interface between the base stations.

The process of detecting the HARQ-ACK by the first base station is the same as the process of detecting the HARQ-ACK by the second base station in step <NUM> to step <NUM> in the embodiment of the present invention, and is not further described herein.

In the method for transmitting a HARQ-ACK shown in <FIG>, transmission of the HARQ-ACK between the UE and the base station is implemented through the cooperation between the UE and the base station.

More specifically, the embodiment shown in <FIG> may be applied to a scenario where cells corresponding to a macro base station and a micro base station are coupled in <FIG>. The macro base station eNB1 deployed at frequency f1 mainly provides system information, radio link monitoring, and mobility management to ensure continuity of services; in addition, the macro base station also provides a semi-persistent scheduling service to ensure continuity of the voice service. The macro base station eNB1 includes multiple micro base stations within its coverage, for example, micro base stations eNB2 and eNB3, where the micro base stations are deployed at frequency f2 and mainly provide transmission of a high data rate service. A non-ideal backhaul exists between the macro base station and each micro base station and between two micro base stations. In this case, the first base station in this embodiment may be the macro base station shown in <FIG>, and the second base station may be any micro base station shown in <FIG>. In this case, so long as the second base station has a capability of receiving the PUCCH sent in the uplink carrier corresponding to the macro base station,
if the UE determines, in step <NUM>, that a HARQ-ACK is sent in an uplink primary carrier corresponding to the first base station through a PUCCH, the second base station may directly receive, on the PUCCH of the uplink primary carrier corresponding to the first base station, the HARQ-ACK sent by the UE, without requiring the first base station to forward the HARQ-ACK to the second base station after the first base station receives the HARQ-ACK, which shortens the time of receiving the HARQ-ACK by the second base station and further shortens the time of performing downlink data scheduling by the second base station for the UE.

In addition, in a case where a PUSCH is transmitted in the current subframe, the UE may further directly determine to send the HARQ-ACK through the PUSCH in the uplink carrier corresponding to the second base station. In this case, the UE directly sends the HARQ-ACK to the second base station, without requiring the first base station to forward the acknowledgement information to the second base station, which can also shorten the time of receiving the HARQ-ACK by the second base station and further shorten the time of performing downlink data scheduling by the second base station for the UE.

Corresponding to the above methods, an embodiment of the present invention further provides an apparatus for transmitting a HARQ-ACK.

<FIG> shows a first embodiment of an apparatus for transmitting a HARQ-ACK according to the present invention. The transmission apparatus may be disposed in a UE, and the transmission apparatus <NUM> includes:.

Preferably, the first determining unit <NUM> may include:.

Preferably, the base stations may include a first base station and a second base station; in this case,.

Preferably, the third determining subunit may be specifically configured to implement, in the following manners, the determining, according to a first preset manner, the channel for transmitting the HARQ-ACK:.

Preferably, the preset priority condition is a HARQ-ACK transmission priority of each base station; and therefore, the third determining subunit is specifically configured to implement, in the following manners, the determining, according to a preset priority condition, the channel for transmitting the HARQ-ACK:.

Preferably, the third determining subunit may be specifically configured to implement, in the following manners, the determining, according to a second preset manner, the channel for transmitting the HARQ-ACK:.

Preferably, the first base station is a macro base station, and the second base station is a micro base station.

Preferably, referring to <FIG>, the bit determining unit <NUM> may include:.

Preferably, the bit determining subunit <NUM> may be specifically configured to:.

Preferably, when it is determined that the channel for transmitting the HARQ-ACK is a PUCCH, referring to <FIG>, the sending unit <NUM> may include:.

Preferably, when a channel format of the PUCCH is format <NUM>, and when the current subframe is configured to transmit a scheduling request, the first resource determining subunit <NUM> may be specifically configured to:.

Preferably, when a channel format of the PUCCH is format 1b, and when the current subframe is configured to transmit a scheduling request, the first resource determining subunit <NUM> may be specifically configured to:
reserve a PUCCH resource for each base station; and determine, according to a base station corresponding to the scheduling request that the current subframe is configured to transmit, the PUCCH resource reserved for the base station as the PUCCH resource for transmitting the HARQ-ACK.

In the apparatus for transmitting a HARQ-ACK shown in <FIG>, a channel for transmitting a HARQ-ACK is determined and a HARQ-ACK feedback bit are determined, and the HARQ-ACK feedback bit are sent on the channel, so that a UE can send the HARQ-ACK to a base station.

<FIG> is a structural diagram of a second embodiment of an apparatus for transmitting a HARQ-ACK according to an embodiment of the present invention. The transmission apparatus may be disposed in a base station, and the transmission apparatus <NUM> includes:.

Preferably, the second determining unit <NUM> may be specifically configured to:.

Preferably, as shown in <FIG>, the bit number determining unit <NUM> may include:.

Preferably, the bit number determining subunit <NUM> may be specifically configured to:.

Preferably, when it is determined that the channel used by the UE for transmitting the HARQ-ACK is a PUCCH, referring to <FIG>, the detecting unit <NUM> may include:.

Preferably, the detecting subunit <NUM> may be further configured to:
detect scheduling request information on the PUCCH resource, and determine, according to the determined PUCCH resource, a base station corresponding to the scheduling request information request, where the base station corresponding to the scheduling request is a base station from which an uplink resource is requested by the scheduling request.

Preferably, the PUCCH resource is a resource semi-statically reserved by the base station for the user equipment, and the base station transmits information indicating the semi-statically reserved PUCCH resource to another base station through an X2 interface.

In the apparatus for transmitting a HARQ-ACK shown in <FIG>, a channel used by a UE for transmitting a HARQ-ACK is determined, the number of bits and transmission time of the HARQ-ACK are determined, and the HARQ-ACK is detected on the channel according to the number of bits and the transmission time. Therefore, a base station can detect the HARQ-ACK.

An embodiment of the present invention further provides a UE for transmitting a HARQ-ACK. Referring to <FIG>, the UE <NUM> includes a first data processor <NUM> and a first radio transceiver <NUM>, where:.

Preferably, the first data processor <NUM> may be specifically configured to implement, in the following manners, the determining a channel for transmitting a HARQ-ACK:.

Preferably, the base stations include a first base station and a second base station;.

Preferably, the first data processor <NUM> may be specifically configured to implement, in the following manners, the determining, according to a first preset manner, the channel for transmitting the HARQ-ACK:.

Preferably, the preset priority condition is a HARQ-ACK transmission priority of each base station; and therefore, the first data processor <NUM> may be specifically configured to implement, in the following manners, the determining, according to a preset priority condition, the channel for transmitting the HARQ-ACK:.

Preferably, the first data processor <NUM> may be specifically configured to implement, in the following manners, the determining, according to a second preset manner, the channel for transmitting the HARQ-ACK:.

Preferably, the first data processor <NUM> may be specifically configured to implement, in the following manners, the determining the HARQ-ACK feedback bit:.

Preferably, the first data processor <NUM> may be specifically configured to implement, in the following manners, the determining the HARQ-ACK feedback bit based on the number of downlink subframes corresponding to the current subframe for each carrier:.

Preferably, when it is determined that the channel for transmitting the HARQ-ACK is a PUCCH, the first radio transceiver <NUM> may be specifically configured to:.

Preferably, when a channel format of the PUCCH is format <NUM>, and when the current subframe is configured to transmit a scheduling request, the first radio transceiver <NUM> may be specifically configured to implement, in the following manners, the determining a PUCCH resource for transmitting the HARQ-ACK:.

Preferably, when a channel format of the PUCCH is format 1b, and when the current subframe is configured to transmit a scheduling request, the first radio transceiver <NUM> may be specifically configured to implement, in the following manners, the determining a PUCCH resource for transmitting the HARQ-ACK:
reserving a PUCCH resource for each base station; and determining, according to a base station corresponding to the scheduling request that the current subframe is configured to transmit, the PUCCH resource reserved for the base station as the PUCCH resource for transmitting the HARQ-ACK.

In the UE shown in <FIG>, the first data processor <NUM> determines a channel for transmitting a HARQ-ACK and determines a HARQ-ACK feedback bit; and the first radio transceiver <NUM> sends the HARQ-ACK feedback bit on the channel determined by the data processor. Therefore, the UE can send the HARQ-ACK to a base station.

An embodiment of the present invention further provides a base station for transmitting a HARQ-ACK. As shown in <FIG>, the base station <NUM> includes a second data processor <NUM> and a second radio transceiver <NUM>, where:.

Preferably, the second data processor <NUM> may be specifically configured to implement, in the following manners, the determining a channel used by a UE for transmitting a HARQ-ACK:.

Preferably, the second data processor <NUM> may be specifically configured to implement, in the following manners, the determining the number of bits of the HARQ-ACK transmitted by the UE:.

Preferably, the second data processor <NUM> may be specifically configured to implement, in the following manners, the determining the number of bits of the HARQ-ACK based on the number of downlink subframes corresponding to the current subframe for each carrier:.

Preferably, when it is determined that the channel used by the UE for transmitting the HARQ-ACK is a PUCCH, the second radio transceiver <NUM> may be specifically configured to:.

Preferably, the second radio transceiver <NUM> may be further configured to detect scheduling request information on the PUCCH resource, and determine, according to the determined PUCCH resource, a base station corresponding to the scheduling request information request, where the base station corresponding to the scheduling request is a base station from which an uplink resource is requested by the scheduling request.

In the base station shown in <FIG>, the second data processor <NUM> determines a channel used by a UE for transmitting a HARQ-ACK, and determines the number of bits of the HARQ-ACK transmitted by the UE; and the second radio transceiver <NUM> detects the HARQ-ACK on the channel according to the number of bits. Therefore, a base station can detect the HARQ-ACK.

A person skilled in the art may clearly understand that, the technique in the embodiments of the present invention may be implemented through software and a necessary general hardware platform. Based on such an understanding, the technical solutions in the embodiments of the present invention essentially, or the part contributing to the prior art may be implemented in the form of a software product. The computer software product is stored in a storage medium, such as a ROM/RAM, a magnetic disk, or an optical disc, and includes several instructions for instructing a computer device (which may be a personal computer, a server, or a network device or the like) to perform the methods described in the embodiments of the present invention or in some parts of the embodiments of the present invention.

The embodiments in this specification are all described in a progressive manner, mutual reference may be made to the same or similar part of the embodiments, and each embodiment focuses on describing difference from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the apparatus embodiment is described simply, and the relevant part may be obtained with reference to the part of the description of the method embodiment.

Claim 1:
A method for transmitting hybrid automatic repeat request-acknowledgement, HARQ-ACK, information performed by a user equipment, UE, comprising
determining (<NUM>, <NUM>) a channel for transmitting a HARQ-ACK;
determining (<NUM>), according to HARQ-ACK timing of each carrier, the number of downlink subframes corresponding to a current subframe for each carrier;
determining (<NUM>) HARQ-ACK feedback bits based on the number of downlink subframes for each carrier; and
sending (<NUM>, <NUM>) the HARQ-ACK feedback bits on the channel in the current subframe;
wherein the HARQ-ACK timing of each carrier comprises: when at least one carrier uses a frequency division duplex, FDD, manner and at least one carrier uses a time division duplex, TDD, manner in carriers for carrier aggregation for the UE, and if, in subframe n, a physical downlink shared channel, PDSCH, is detected in the carrier that uses the TDD manner or a physical downlink control channel, PDCCH, indicating semi-persistent scheduling release is detected in the carrier that uses the TDD manner, the HARQ-ACK corresponding to the PDSCH or the PDCCH shall be fed back in subframe n+<NUM>;
wherein the channel is a PUCCH, and the determining the HARQ-ACK feedback bit comprises:
determining the HARQ-ACK feedback bit based on the number of carriers configured for the UE, a transmission mode of each carrier, and the number of downlink subframes corresponding to the current subframe for each carrier, wherein
the number of the HARQ-ACK bits satisfies following formula: OACK = Nsubframe ·(C+C<NUM>), where OACK is the number of bits of the HARQ-ACK, Nsubframe is the number of downlink subframes corresponding to the current subframe, C is the number of configured carriers, and C<NUM> is the number of carriers where a configured transmission mode may support dual-codeword transmission.