WO2014157923A1

WO2014157923A1 - Method and apparatus for transmitting harq-ack in inter-enb carrier aggregation system

Info

Publication number: WO2014157923A1
Application number: PCT/KR2014/002518
Authority: WO
Inventors: Jingxing Fu; Yingyang Li; Chengjun Sun
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2013-03-25
Filing date: 2014-03-25
Publication date: 2014-10-02
Anticipated expiration: 2015-09-25
Also published as: CN104079390A

Abstract

Embodiments of the present application provides a method for transmitting HARQ-ACK feedback information in an Inter-eNB CA system. In the method, UE receives configuration information from Primary cell eNB (Pcell eNB), the configuration information configuring the UE to work in an Inter-eNB CA mode; the UE receives Physical Downlink Shared Channel (PDSCH) data from each cell involved in Inter-eNB carrier aggregation; and the UE sends HARQ-ACK feedback information of the PDSCH data received from each cell of the Pcell eNB to the Pcell eNB, and sends HARQ-ACK feedback information of the PDSCH data received from each cell of each Secondary cell eNB (Scell eNB) to a corresponding Scell eNB via a Scell designated by the corresponding Scell eNB. Embodiments of the present application also provide UE. By the embodiments of the present application, HARQ-ACK feedback information can be transmitted in the Inter-eNB CA system.

Description

METHOD AND APPARATUS FOR TRANSMITTING HARQ-ACK IN INTER-ENB CARRIER AGGREGATION SYSTEM

The present invention relates to wireless communication technologies, and more particularly, to a method and apparatus for transmitting hybrid automatic repeat-request acknowledgement (HARQ-ACK) information in an Inter-eNB Carrier Aggregation (Inter-eNB CA) system.

In current Long Term Evolution (LTE) system, the maximum bandwidth supported by each cell is 20MHz. In order to increase peak rate of User Equipment (UE), the Carrier Aggregation technique is introduced into a LTE-Advanced system. By the Carrier Aggregation technique, the UE can communicate simultaneously with cells which are controlled by the same evolved NodeB (eNB) and which work at different carrier frequencies, the maximum transmission bandwidth reaches 100MHz, and uplink and downlink peak rates of the UE may be increased by several times in principle.

As for UE working in the Carrier Aggregation, aggregated cells are divided into a Primary Cell (PCell) and a Secondary Cell (SCell).

In order to extend the application scope of the Carrier Aggregation technique and to further increase the peak rates of the UE, the Inter-eNB Carrier Aggregation technique may be a trend of LTE-Advanced development. The Inter-eNB Carrier Aggregation technique means that cells transmitting data simultaneously to the same UE need not belong to one eNB, that is, as shown in Figure 1, the cells may belong to different eNBs. The eNB covering Pcells is called a Pcell eNB, and the eNB covering only Scells is called a Scell eNB. As such, in the network environment where coverage of different eNBs is overlapped, the Carrier Aggregation technique can still be used to increase working bandwidth of the UE and thereby increase peak transmission rate of the UE.

However, the difference between the Inter-eNB Carrier Aggregation technique and the existing one-eNB Carrier Aggregation technique also raises new issues to the application of the Carrier Aggregation technique. For example, during transmission of HARQ-ACK feedback information, the HARQ-ACK feedback information is transmitted only in the Pcells at the present, and resources occupied by the transmission of HARQ-ACK feedback information are obtained by mapping of the lowest Control Channel Element (CCE) index used by a Physical Downlink Control Channel (PDCCH) scheduling a Physical Downlink Shared Channel (PDSCH), or are indicated in a HARQ-ACK resource indicator (ARI) field on the PDCCH scheduling the PDSCH. However, in the Inter-eNB system, PDSCH data transmitted in cells covered by different eNBs are scheduled by different eNBs, and the lowest CCE index information used by the PDCCH scheduled by different eNBs as well as the resources indicated in the ARI field on the PDCCH scheduling the PDSCH can not be shared between different eNBs, i.e., one eNB does not know the lowest CCE index information used by the PDCCH scheduled by another eNB, or the resources indicated in the ARI field on the PDCCH scheduling the PDSCH. Therefore, the existing transmission technique of HARQ-ACK feedback information can not be used normally in the Inter-eNB system.

As can be seen, there are a lot of new problems in the transmission of HARQ-ACK feedback information in the Inter-eNB Carrier Aggregation technique, e.g., methods described in a LTE-Advanced protocol can not be simply copied and used. Moreover, there is no solution for those problems yet according to current research results.

In view of the above, the present application provides a method and UE for transmitting hybrid automatic repeat-request acknowledgement (HARQ-ACK) information in two kinds of Inter-eNB Carrier Aggregation (Inter-eNB CA) systems, which can realize transmission of the HARQ-ACK) information in the Inter-eNB CA) systems.

To achieve the above, the technical scheme of the embodiments of the present application are implemented as follows:

An embodiment of the present application provides a method for transmitting Hybrid Automatic Repeat-Request Acknowledgement (HARQ-ACK) feedback information in an Inter-eNB Carrier Aggregation (Inter-eNB CA) system. The method includes:

receiving, by User Equipment (UE), configuration information from a Primary cell eNB (Pcell eNB), the configuration information configuring the UE to work in an Inter-eNB CA mode;

receiving, by the UE, Physical Downlink Shared Channel (PDSCH) data from each cell involved in Inter-eNB carrier aggregation; and

sending, by the UE, HARQ-ACK feedback information of the PDSCH data received from each cell of the Pcell eNB to the Pcell eNB, and sending, by the UE, HARQ-ACK feedback information of the PDSCH data received from each cell of each Secondary cell Scell eNB to a corresponding Scell eNB via a Scell designated by the corresponding Scell eNB.

Preferably, the Pcell and a Scell designated by each Scell eNB work in a Time Division Duplex (TDD) mode; and

the UE receives the PDSCH data of each cell sent by the Pcell eNB on a subframe k, and receives the PDSCH data of each cell sent by a Scell eNB c on a subframe |k-Nc|, wherein k represents a sequence number of a subframe, c represents a sequence number of a Scell eNB, Nc represents a subframe offset between downlink transmission of each Scell eNB and the Pcell eNB, Nc is a natural number and Nc for each Scell eNB involved in the Inter-eNB carrier aggregation is different from each other.

Preferably, eNBs involved in the Inter-eNB carrier aggregation are one Pcell eNB and one Scell eNB; and

the method further includes: transmitting, by the Pcell and a Scell designated by the Scell eNB, the HARQ-ACK feedback information on one or more subframes of

subframes

2, 3, 7 and 8;

if TDD uplink and downlink configurations of the Pcell or the Scell designated by the Scell eNB are 1, 2, 4 and 5, a HARQ-ACK timing relation of the Pcell or the Scell designated by the Scell eNB follows a HARQ-ACK relation of the TDD uplink and downlink configurations of the Pcell or the Scell designated by the Scell eNB; if the TDD uplink and downlink configurations of the Pcell or the Scell designated by the Scell eNB are 3, the HARQ-ACK timing relation of the Pcell or the Scell designated by the Scell eNB follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 4; if the TDD uplink and downlink configurations of the Pcell or the Scell designated by the Scell eNB are 0 and 6, the HARQ-ACK timing relation of the Pcell or the Scell designated by the Scell eNB follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 1.

Preferably, eNBs involved in the Inter-eNB carrier aggregation are one Pcell eNB and one to four Scell eNBs; and

the method further includes: transmitting, by the Pcell and a Scell designated by each Scell eNB, the HARQ-ACK feedback information on one or more of

subframes

2 and 7;

if TDD uplink and downlink configurations of the Pcell or the Scell designated by said each Scell eNB are 0, 1, 2 and 6, a HARQ-ACK timing relation of the Pcell or the Scell designated by said each Scell eNB follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 2; if the TDD uplink and downlink configurations of the Pcell or the Scell designated by each Scell eNB are 3, 4 and 5, the HARQ-ACK timing relation of the Pcell or the Scell designated by each Scell eNB follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 5.

Preferably, at least one of the Pcell and a Scell designated by each Scell eNB work in a Time Division Duplex (TDD) mode, and at least one of the Pcell and the Scell designated by each Scell eNB work in a Frequency Division Duplex (FDD) mode; and

the UE transmits the HARQ-ACK feedback information of the Pcell and the Scell designated by each Scell eNB on different subframes.

Preferably, eNBs involved in the Inter-eNB carrier aggregation are one Pcell eNB and one Scell eNB; wherein a cell working in the TDD mode of the Pcell and a Scell designated by the Scell eNB transmits the HARQ-ACK feedback information on one or more of

subframes

2, 3, 7 and 8, and wherein a cell working in the FDD mode of the Pcell and a Scell designated by the Scell eNB transmits the HARQ-ACK feedback information on one or more of

subframes

9, 0, 1 4 and 5;

wherein, if TDD uplink and downlink configurations of the cell working in the TDD mode are 1, 2, 4 and 5, a HARQ-ACK timing relation of the cell working in the TDD mode follows a HARQ-ACK relation of the TDD uplink and downlink configurations of the cell working in the TDD mode; if the TDD uplink and downlink configurations of the cell working in the TDD mode are 3, the HARQ-ACK timing relation of the cell working in the TDD mode follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 4; if the TDD uplink and downlink configurations of the cell working in the TDD mode are 0 and 6, the HARQ-ACK timing relation of the cell working in the TDD mode follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 1; and

a timing relation of the cell working in the FDD mode is that: a subframe 8 of a radio frame n-1 of the cell working in the FDD mode and a subframe 9 of the radio frame n-1 of the cell working in the FDD mode transmit the HARQ-ACK feedback information on a subframe 4 of a radio frame n, a subframe 0 of the radio frame n and a subframe 1 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 5 of the radio frame n, a subframe 2 of the radio frame n and a subframe 3 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 9 of the radio frame n, the subframe 4 of the radio frame n and the subframe 5 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 0 of a radio frame n+1, and a subframe 6 of the radio frame n and a subframe 7 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 1 of the radio frame n+1.

Preferably, eNBs involved in the Inter-eNB carrier aggregation are one Pcell eNB and one to four Scell eNBs; wherein a cell working in the TDD mode of the Pcell and a Scell designated by each Scell eNB transmits the HARQ-ACK feedback information on one or more of

subframes

2 and 7, and a cell working in the FDD mode of the Pcell and the Scell designated by each Scell eNB transmits the HARQ-ACK feedback information on subframes N1 and N2, wherein |N2-N1|=5，N1≠2, and N1 of each cell is different from each other;

if TDD uplink and downlink configurations of the cell working in the TDD mode are 0, 1, 2 and 6, a HARQ-ACK timing relation of the cell working in the TDD mode follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 2; if the TDD uplink and downlink configurations of the cell working in the TDD mode are 3, 4 and 5, the HARQ-ACK timing relation of the cell working in the TDD mode follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 5;

the cell working in the FDD mode follows a HARQ-ACK timing relation that HARQ-ACK feedback information of the 4th, 5th, 6th, 7th and 8th subframes before the subframe N1 is transmitted on the subframe N1, and that HARQ-ACK feedback information of the 4th, 5th, 6th, 7th and 8th subframes before the subframe N2 is transmitted on the subframe N2.

Preferably, the Pcell and a Scell designated by each Scell eNB work in a Frequency Division Duplex (FDD) mode;

Preferably, eNBs involved in the Inter-eNB carrier aggregation are one Pcell eNB and one Scell eNB;

one cell of the Pcell and a Scell designated by the Scell eNB transmits the HARQ-ACK feedback information on

subframes

2, 3, 6, 7 and 8, and another cell transmits the HARQ-ACK feedback information on

subframes

9, 0, 1, 4 and 5;

the one cell follows a HARQ-ACK timing relation that: a subframe 9 of a radio frame n-1 and a subframe 0 of a radio frame n transmit the HARQ-ACK feedback information on a subframe 6 of the radio frame n, a subframe 1 of the radio frame n and a subframe 2 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 7 of the radio frame n, a subframe 3 of the radio frame n and a subframe 4 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 8 of the radio frame n, a subframe 5 of the radio frame n and a subframe 6 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 2 of a radio subframe n+1, and the subframe 7 of the radio frame n and the subframe 8 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 3 of the radio frame n+1;

another cell follows a HARQ-ACK timing relation that: a subframe 8 of a radio frame n-1 and a subframe 9 of the radio frame n-1 transmit the HARQ-ACK feedback information on a subframe 4 of a radio frame n, a subframe 0 of the radio frame n and a subframe 1 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 5 of the radio frame n, a subframe 2 of the radio frame n and a subframe 3 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 9 of a radio frame n+1, the subframe 4 of the radio frame n and the subframe 5 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 0 of the radio subframe n+1, and a subframe 6 of the radio frame n and a subframe 7 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 1 of the radio frame n+1.

Preferably, eNBs involved in the Inter-eNB carrier aggregation are one Pcell eNB and one to four Scell eNBs;

the Pcell and a Scell designated by each Scell eNB transmits the HARQ-ACK feedback information on subframes N3 and N4, wherein |N4-N3|=5，where N3 of each cell is different from each other;

HARQ-ACK feedback information of the 4th, 5th, 6th, 7th and 8th subframes before the subframe N3 is transmitted on the subframe N3, and HARQ-ACK feedback information of the 4th, 5th, 6th, 7th and 8th subframes before the subframe N4 is transmitted on the subframe N4.

Preferably, if two subframes of different cells for transmitting the HARQ-ACK feedback information are overlapped with each other, a first subframe of the two subframes uses a shortened Physical Uplink Control Channel (PUCCH) transmission format if tail of the first subframe is overlapped with head of a second subframe of the two subframes.

An embodiment of the present application provides User Equipment (UE), applicable to transmitting Hybrid Automatic Repeat-Request Acknowledgement (HARQ-ACK) feedback information in an Inter-eNB Carrier Aggregation (Inter-eNB CA) system. The UE includes:

a configuring module, adapted to configure the UE to work in an Inter-eNB carrier aggregation mode according to configuration information received from a Primary cell (Pcell) eNB;

a receiving module, adapted to receive Physical Downlink Shared Channel (PDSCH) data from each cell involved in Inter-eNB carrier aggregation;

a feedback module, adapted to transmit HARQ-ACK feedback information of the PDSCH data received from each cell of the Pcell eNB to the Pcell eNB, and transmit HARQ-ACK feedback information of the PDSCH data received from each cell of each Secondary cell (Scell) eNB to a corresponding Scell eNB via a Scell designated by the corresponding Scell eNB

As can be seen, according to the method and UE for transmitting HARQ-ACK feedback information in the Inter-eNB carrier aggregation system, HARQ-ACK feedback information of different eNBs can be transmitted respectively in the Inter-eNB carrier aggregation system due to relevant configurations at both the base station side and the UE side.

Additional merits and explanation of the present application will be given in the following description, which will be detailed in the following description or in the practice implementation of the present application.

Figure 1 is a schematic diagram of conventional Inter-eNB carrier aggregation.

Figure 2 is a flowchart of a method for transmitting HARQ-ACK feedback information in an Inter-eNB carrier aggregation system in accordance with the present application.

Figure 3 is a schematic diagram showing that a subframe offset is introduced between a Pcell and a main Scell when both the Pcell and the main Scell work in a Time Division Duplex (TDD) mode in accordance with an embodiment of the present application.

Figure 4 is a schematic diagram showing that there is a “three-frame + delta” time delay between a Pcell and a main Scell in accordance with a first embodiment of the present application.

Figure 5 is a schematic diagram of some subframes in which a shortened PUCCH transmission format is used to transmit HARQ-ACK feedback information in accordance with the present application.

Figure 6 is a schematic diagram showing that there is a “one-frame + delta” time delay between a Pcell and a main Scell in accordance with a second embodiment of the present application.

Figure 7 is a schematic diagram showing transmission of HARQ-ACK feedback information in a Pcell and a main Scell by way of Time Division Multiplexing when the Pcell and the main Scell work respectively in a TDD mode and a Frequency Division Duplex (FDD) mode in accordance with the present application.

Figure 8 is a schematic diagram of a timing relation of HARQ-ACK feedback information in a Pcell in accordance with a third embodiment and a firth embodiment of the present application.

Figure 9 is a schematic diagram showing that there is a “one-frame + delta” time delay between a Pcell and a main Scell in accordance with a fourth embodiment of the present application.

Figure 10 is a schematic diagram showing transmission of HARQ-ACK feedback information in a Pcell and a main Scell by way of Time Division Multiplexing when both the Pcell and the main Scell work in a FDD mode in accordance with the present application.

Figure 11 is a schematic diagram of a timing relation of HARQ-ACK feedback information in a main Scell in accordance with a fifth embodiment of the present application.

Figure 12 is a schematic diagram showing that there is a “delta” time delay between the Pcell and the main Scell in accordance with the fifth embodiment of the present application.

Figure 13 is a schematic diagram showing transmission of HARQ-ACK feedback information in a Pcell and a main Scell by way of Time Division Multiplexing in accordance with a sixth embodiment of the present application.

Figure 14 is a schematic diagram of a timing relation of HARQ-ACK feedback information in the Pcell in accordance with the sixth embodiment of the present application.

Figure 15 is a schematic diagram of a structure of preferred UE in accordance with the present application.

Embodiments of the present application will be described hereinafter in detail with reference to accompanying drawings. In the drawings, the same or similar reference signs represent the same or similar elements or elements with the same or similar functions. The embodiments described with referent to the drawings are exemplary, only for explaining the present application but not for limiting the scope of the present application.

In order to achieve the objective of the present application, the present application provides a method for transmitting HARQ-ACK feedback information in an Inter-eNB carrier aggregation system. Figure 2 is a flowchart of a method for transmitting HARQ-ACK feedback information in an Inter-eNB carrier aggregation system in accordance with the present application. As shown in Figure 2, the method includes the following:

Step 201: UE receives configuration information from a Pcell eNB, the configuration information configuring the UE to work in an Inter-eNB carrier aggregation mode.

Step 202: The UE receives data from each cell involved in Inter-eNB carrier aggregation. Specifically, the UE receives PDCCH data and PDSCH data respectively from each cell of a Pcell eNB and each cell of a Scell eNB.

Step 203: The UE sends HARQ-ACK feedback information of the PDSCH data received from each cell of the Pcell eNB to the Pcell eNB, and sends HARQ-ACK feedback information of the PDSCH data received from each cell of the Scell eNB to a corresponding Scell eNB via a Scell designated by the corresponding Scell eNB.

In this embodiment, the UE determines a HARQ-ACK timing relation of the Pcell and the Scell designated by each Scell eNB according to a duplex mode of the Pcell and the Scell designated by each Scell eNB. The duplex mode includes a Time Division Duplex mode and a Frequency Division Duplex mode.

In the present application, the UE may receive the PDCCH sent by the Pcell eNB via the Pcell or Scell of the Pcell eNB and may receive the PDSCH scheduled by the PDCCH via the Pcell or Scell of the Pcell eNB, and then may feed back the HARQ-ACK feedback information of the PDSCH scheduled in the Pcell eNB via the Pcell; the UE may also receive the PDCCH sent by the Scell eNB via the Scell of the Scell eNB and may receive the PDSCH scheduled by the PDCCH via the Scell of the Scell eNB, and then may feed back the HARQ-ACK feedback information of the PDSCH scheduled in the Scell eNB via a Scell designated by the Scell eNB. The Scell designated by the Scell eNB is a Scell designated in the Scell eNB to transmit the HARQ-ACK feedback information to the Scell eNB, and each Scell eNB designates one respective Scell to transmit the HARQ-ACK feedback information. To be simplified, the Scell designated in the Scell eNB will be called main Scell of the Scell eNB in the subsequent description of the present application.

With respect to the situation that the UE may receive the PDCCH and the PDSCH scheduled by the PDCCH from the Pcell eNB or the Scell eNB and then may send the HARQ-ACK feedback information of the PDSCH respectively via the Pcell or the main Scell, a timing relation and transmission method of HARQ-ACK feedback information of each cell will be described with several different configurations of Inter-eNB CA in detail

The HARQ-ACK feedback information of the PDSCH received by the UE from the Pcell eNB is fed back to the Pcell eNB via the Pcell, and the HARQ-ACK feedback information of the PDSCH received by the UE from the Scell eNB is fed back to the Scell eNB via the main Scell. To ensure that the UE would not simultaneously transmit the HARQ-ACK feedback information via two or more cells, Time Division Multiplexing is used in the present application so as to make the Pcell and the main Scell transmit the HARQ-ACK feedback information at different time.

There are the following 3 situations when the Pcell eNB configures the UE to receive the PDCCH and the PDSCH scheduled by the PDCCH from the Pcell and the Scell eNB respectively.

Situation 1: The Pcell and each main Scell work in the TDD mode.

The HARQ-ACK feedback information of the PDSCH received by the UE from the Pcell eNB is fed back to the Pcell eNB via the Pcell, and the HARQ-ACK feedback information of the PDSCH received by the UE from the Scell eNB is fed back to the Scell eNB via the main Scell. To ensure that the UE would not simultaneously transmit the HARQ-ACK feedback information via two or more cells, a subframe offset Nc is introduced between the Pcell and the main Scell so as to make the Pcell and the main Scell transmit the HARQ-ACK feedback information at different time. Moreover, the subframe offsets for all cells of the same eNB are the same. Specifically, it is supposed that k represents a sequence number of a subframe, that c represents a sequence number of a Scell eNB, and that Nc represents a subframe offset of downlink transmission of the Pcell eNB and each Scell eNB, wherein Nc is a natural number and Nc representing each Scell eNB involved in the Inter-eNB carrier aggregation is different from each other; in this case, after the Pcell eNB configures Nc for each Scell eNB, the UE receives the PDSCH data sent by the Pcell eNB on subframe k of each cell and receives the PDSCH data sent by the Scell eNB c on subframe |k-Nc| of each cell. As shown in Figure 3, the Pcell and Scell 1 are cells covered by the Pcell eNB, and the main Scell and Scell 2 are cells covered by the Scell eNB; the subframe offset Nc between the Pcell and the main Scell is three subframes, and respective subframe offsets Nc between all the cells under the Pcell eNB and all the cells under the Scell eNB are also three subframes. The subframe offset between the Pcell and the main Scell may be sent to the UE by the Pcell eNB via configuration information, and as such, the UE may receive data from each cell involved in the Inter-eNB carrier aggregation according to the configuration information. Moreover, there is an offset of Nc subframes between the data received by the UE from each cell of the Pcell eNB and the data received by the UE from each cell of each Scell eNB due to the configuration information.

The situation 1 will be hereinafter described in detail with reference to the first embodiment and the second embodiment.

In the first embodiment, it is supposed that the UE configures a Carrier Aggregation (CA) system of two cells which belong to the Pcell eNB and the Scell eNB respectively. The cell belonging to the Pcell eNB is called Pcell while the cell belonging to the Scell eNB is called main Scell. Both the Pcell and the main Scell work in the TDD mode. An offset between a subframe 0 of the main Scell and a subrame 0 of the Pcell is configured as three subframes. Because respective distances from the UE to the Pcell eNB and to the Scell eNB are different, there may be an extra delay delta between the subframe 0 of the Pcell and the subframe 0 of the main Scell. Thereby, at the UE side, there is a delay of “three-subframe + delta” between the subframe 0 of the Pcell and the subframe 0 of the main Scell. Each radio frame contains 10 subframes. Due to symmetry of subframes, the effect to configure a 3-subframe offset between the subframe 0 of the main Scell and the subframe 0 of the Pcell is the same as the effect to configure a 2-subframe offset between the subframe 0 of the main Scell and the subframe 0 of the Pcell. It is hence recommended to configure the 2-subframe offset in the present application.

Based on an analysis of current TDD uplink and downlink configurations, subframes in the Pcell and the main Scell for transmitting HARQ-ACK feedback information are determined as

subframes

2, 3, 7 and 8 in accordance with this embodiment in order to balance the number of subframes available for transmitting the HARQ-ACK feedback information in the Pcell and the main Scell. In other words, the HARQ-ACK feedback information of the Pcell and the main Scell may be transmitted on the

subframes

2, 3, 7 and 8, as shown in Figure 4.

It will be described hereinafter by an example that there is a “3-subframe + delta” delay between the subframe 0 of the main Scell and the subframe 0 of the Pcell.

Based on the suppose that the HARQ-ACK feedback information of the Pcell and the main Scell is transmitted on the

subframes

2, 3, 7 and 8, the Pcell and the main Scell follow respective reference timing in this embodiment. A method of determining the reference timing will be described hereinafter. If the TDD uplink and downlink configurations of the Pcell or main Scell are 1, 2 4 and 5, a timing relation of HARQ-ACK feedback information of the Pcell or main Scell may follow a timing relation of the HARQ-ACK feedback information of the TDD uplink and downlink configurations of the Pcell or main Scell. If the TDD uplink and downlink configurations of the Pcell or main Scell are 3, the timing relation of the HARQ-ACK feedback information of the Pcell or main Scell may follow the timing relation of the HARQ-ACK feedback information of the TDD uplink and downlink configuration 4. If the TDD uplink and downlink configurations of the Pcell or main Scell are 0 and 6, the timing relation of the HARQ-ACK feedback information of the Pcell or main Scell may follow the timing relation of the HARQ-ACK feedback information of the TDD uplink and downlink configuration 1.

There is a “3-subframe + delta” delay between a downlink subframe of the Pcell and a downlink subframe of the main Scell. If delta is 0 microsecond and subframes of the two cells are aligned, a subframe 3 and a subframe 8 of the Pcell are configured by high-layer signaling to use a normal PUCCH transmission format. If delta is 30 microseconds and subframes of the two cells are not aligned, a subframe 7 of the Pcell is overlapped with a subframe 3 of the main Scell, and a subframe 2 of the Pcell is also overlapped with a subframe 8 of the main Scell, as shown in Figure 4. In order to avoid the overlapping between transmission of HARQ-ACK feedback information on the subframe 7 of the Pcell and that on the subframe 3 of the main Scell as well as the overlapping between transmission of HARQ-ACK feedback information on the subframe 2 of the Pcell and that on the subframe 8 of the main Scell, the

subframes

3 and 8 of the main Scell are configured by high-layer signaling to use a shortened PUCCH transmission format.

Specifically, referring to Figure 5, each subframe consists of two time slots, called time slot 0 and time slot 1, and each subframe contains 14 OFDM symbols, and the shortened PUCCH transmission format in accordance with the present application is that:

OFDM symbols

0, 1, 2, 3, 4 and 5 in slot 1 are used for the PUCCH transmission while OFDM symbol 6 in slot 1 is not used, as shown in Figure 5.

If two subframes of different cells for transmitting the HARQ-ACK feedback information are overlapped in time, it is necessary to determine which subframe uses the shortened PUCCH transmission format. The determining method is that: if the tail of a first subframe of the two subframes is overlapped with the head of a second sbuframe thereof, the first subframe uses the shortened PUCCH transmission format.

In the second embodiment, it is supposed that the UE configures a CA system of two cells which belong to the Pcell eNB and the Scell eNB respectively. The cell belonging to the Pcell eNB is called Pcell while the cell belonging to the Scell eNB is called main Scell. Both the Pcell and the main Scell work in the TDD mode. An offset of 1 subframe is configured between a subframe 0 of the main Scell and a subrame 0 of the Pcell, and thus there is a delay of “one-subframe + delta” between the subframe 0 of the Pcell and the subframe 0 of the main Scell.

In this embodiment, subframes for transmitting the HARQ-ACK feedback information in the Pcell and the main Scell are

subframe

2 and 7, that is, the HARQ-ACK feedback information in the Pcell and the main Scell may be transmitted on the

sbuframes

2 and 7, as shown in Figure 6. In this embodiment, as for each eNB involved in the carrier aggregation, the UE may transmit the HARQ-ACK feedback information to the eNB on at most two subframes. Thereby, the method in this embodiment is particularly applicable to the situation that eNBs involved in the carrier aggregation are more than 2 and less or equal to 5.

subframes

2 and 7, the Pcell and the main Scell follow a timing relation as follows: if TDD uplink and downlink configurations of the Pcell or main Scell are 0, 1, 2 and 6, a timing relation of the HARQ-ACK feedback information of the Pcell or main Scell may follow a timing relation of the HARQ-ACK feedback information of the TDD uplink and downlink configuration 2; if the TDD uplink and downlink configurations of the Pcell or main Scell are 3, 4 and 5, the timing relation of the HARQ-ACK feedback information of the Pcell or main Scell may follow the timing relation of the HARQ-ACK feedback information of the TDD uplink and downlink configuration 5.

At the UE side, there is a “1-subframe + delta” delay between the subframe 0 of the main Scell and the subframe 0 of the Pcell, as shown in Figure 6; if delta is 30 microsecond and subframes of the two cells are not aligned, a subframe 2 of the Pcell is not overlapped with a subframe 2 of the main Scell and a subframe 7 of the Pcell is not overlapped with a subframe 7 of the main Scell, and the

subframes

2 and 7 of the Pcell are configured by high-layer signaling to use a normal PUCCH transmission format.

Situation 2: At least one of a Pcell and a Scell designated by each Scell eNB works in the TDD mode, and at least one of the Pcell and the Scell designated by each Scell eNB works in the FDD mode.

The HARQ-ACK feedback information of the PDSCH received by the UE from the Pcell eNB is fed back to the Pcell eNB via the Pcell, and the HARQ-ACK feedback information of the PDSCH received by the UE from the Scell eNB is fed back to the Scell eNB via the main Scell. In order to ensure that the UE does not send HARQ-ACK feedback information via two or more cells simultaneously, the HARQ-ACK feedback information of the Pcell and the HARQ-ACK feedback information of the main Scell are transmitted by way of Time Division Multiplexing so that the Pcell and the main Scell send the HARQ-ACK feedback information respectively at different time, as shown in Figure 7.

The situation 2 will be hereinafter described in detail with reference to a third embodiment and a fourth embodiment.

In the third embodiment, it is supposed that the UE configures a CA system of two cells which belong to the Pcell eNB and the Scell eNB respectively. The cell belonging to the Pcell eNB is called Pcell while the cell belonging to the Scell eNB is called main Scell. The main Scell works in the TDD mode. At the UE side, there is a delta delay between a subframe 0 of the main Scell and a subframe 0 of the Pcell. To be compatible with the first embodiment, the main Scell transmits the HARQ-ACK feedback information on

subframe

2, 3, 7 and 8, while the Pcell transmits the HARQ-ACK feedback information on subframes different from the subframes of the main Scell in time, and specifically, the Pcell transmits the HARQ-ACK feedback information on

subframes

9, 0, 1, 4 and 5, as shown in Figure 7.

The timing relation of the HARQ-ACK feedback information of the Pcell is as follows: a subframe 8 of a radio frame n-1 and a subframe 9 of the radio frame n-1 transmit the HARQ-ACK feedback information on a subframe 4 of a radio frame n, a subframe 0 of the radio frame n and a subframe 1 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 5 of the radio frame n, a subframe 2 of the radio frame n and a subframe 3 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 9 of a radio frame n+1, the subframe 4 of the radio frame n and the subframe 5 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 0 of the radio subframe n+1, and a subframe 6 of the radio frame n and a subframe 7 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 1 of the radio frame n+1, as shown in Figure 8.

Based on the suppose that the HARQ-ACK feedback information of the main Scell is transmitted on

subframes

2, 3, 7 and 8, the HARQ-ACK timing relation of the main Scell is as follows: if TDD uplink and downlink configurations of the main Scell are 1, 2, 4 and 5, a timing relation of the HARQ-ACK feedback information of the main Scell follows a timing relation of the HARQ-ACK feedback information of the TDD uplink and downlink configurations of the main Scell; if the TDD uplink and downlink configurations of the main Scell are 3, the timing relation of the HARQ-ACK feedback information of the main Scell follows the timing relation of the HARQ-ACK feedback information of the TDD uplink and downlink configuration 4; if the TDD uplink and downlink configurations of the main Scell are 0 and 6, the timing relation of the HARQ-ACK feedback information of the main Scell follows the timing relation of the HARQ-ACK feedback information of the TDD uplink and downlink configuration 1 .

The

subframes

3 and 8 of the main Scell may need to use a shortened PUCCH transmission format according to different delta values.

Specifically, if delta is 0 microsecond and subframes of the two cells are aligned, the subframe 3 and subframe 8 of the main Scell are configured by high-layer signaling to use a normal PUCCH transmission format, and a subframe 1 of the Pcell is also configured by high-layer signaling to use a normal PUCCH transmission format.

If delta is 30 microseconds and subframes of the two cells are not aligned, as shown in Figure 7. In this case, a subframe 3 of a radio frame n of the main Scell is overlapped with a subframe 4 of the radio frame n of the Pcell, and a subframe 8 of the radio frame n of the main Scell is overlapped with a subframe 9 of a radio frame n+1 of the Pcell. In order to avoid such overlapping of subframes, the subframe 3 and subframe 8 of the main Scell are configured by high-layer signaling to use a shortened PUCCH transmission format, that is,

OFDM symbols

0, 1, 2, 3, 4 and 5 of the

subframes

3 and 8 are used for the PUCCH transmission in time slot 1 while OFDM symbol 6 in time slot 1is not used, as shown in Figure 5.

In the fourth embodiment, it is supposed that the UE configures a CA system of two cells which belong to the Pcell eNB and the Scell eNB respectively. The cell belonging to the Pcell eNB is called Pcell while the cell belonging to the Scell eNB is called main Scell. The main Scell works in the TDD mode. To be compatible with the second embodiment, the main Scell sends the HARQ-ACK feedback information on

subframes

2 and 7, and the Pcell transmits the HARQ-ACK feedback information on subframes having one-frame interleaving with the subframes of the main Scell, i.e., the Pcell transmits the HARQ-ACK feedback information on

subframes

1 and 6, as shown in Figure 9.

Based on the suppose that the main Scell transmits the HARQ-ACK feedback information on the

subframes

2 and 7, a HARQ-ACK timing relation of the main Scell is that: if TDD uplink and downlink configurations of the main Scell are 0, 1, 2 and 6, the timing relation of the HARQ-ACK feedback information of the main Scell follows the timing relation of the HARQ-ACK feedback information of the TDD uplink and downlink configuration 2; if the TDD uplink and downlink configurations of the main Scell are 3, 4 and 5, the timing relation of the HARQ-ACK feedback information of the main Scell follows the timing relation of the HARQ-ACK feedback information of the TDD uplink and downlink configuration 5.

Based on the suppose that the Pcell transmits the HARQ-ACK feedback information on the

subframes

1 and 6, the timing relation of the HARQ-ACK feedback information of the Pcell is that:

subframes

3, 4, 5, 6 and 7 of a radio frame n transmit the HARQ-ACK feedback information on a subframe 1 of a radio frame n+1, and

subframes

8 and 9 of the radio frame n as well as

subframes

0, 1 and 2 of the radio frame n+1 transmit the HARQ-ACK feedback information on a subframe 6 of the radio frame n+1.

There is a delta delay between a subframe 9 of a radio frame n-1 of the Pcell and a subframe 9 of a radio frame n-1 of the main Scell, as shown in Figure 9. If delta is 0 microsecond and subframes of the two cells are aligned, the subframe 1 and subframe 6 of the Pcell are configured by high-layer signaling to use a normal PUCCH transmission format. If delta is 30 microseconds and subframes of the two cells are not aligned, the subframe 1 of the Pcell is not overlapped with the subframe 2 of the main Scell while the subframe 6 of the Pcell is not overlapped with the subframe 7 of the main Scell, and the subframe 1 and subframe 6 of the Pcell are configured by high-layer signaling to use a normal PUCCH transmission format.

In this embodiment, as for each eNB involved in the carrier aggregation, the UE may transmit the HARQ-ACK feedback information to the eNB on at most two subframes. Thereby, the method in this embodiment is particularly applicable to the case that the eNBs involved in the carrier aggregation are more than 2 and less or equal to 5. In this embodiment, only the situation that the eNBs involved in the carrier aggregation are two is described as an example. If the eNBs involved in the carrier aggregation are three, a second main Scell may have one-frame interleaving with the above-mentioned Pcell and main Scell. For example, the HARQ-ACK feedback information may be transmitted on

subframes

3 and 8 of the second main Scell and a HARQ-ACK timing relation of the second main Scell may be determined according to the determine method mentioned above. By way of formulas, it may be |N2-N1|=5，wherein N1 and N2 are subframes applicable to transmitting the HARQ-ACK feedback information in a cell working in the FDD mode, N1≠2 and N1 of each cell is different from each other. The cell working in the FDD mode follows the HARQ-ACK timing relation that: the HARQ-ACK feedback information of the 4th, 5th, 6th, 7th and 8th subframes before the subframe N1 is transmitted on the subframe N1, and the HARQ-ACK feedback information of the 4th, 5th, 6th, 7th and 8th subframes before the subframe N2 is transmitted on the subframe N2.

Situation 3: The Pcell and each main Scell work in the FDD mode.

The HARQ-ACK feedback information of the PDSCH received by the UE from the Pcell eNB is fed back to the Pcell eNB via the Pcell, and the HARQ-ACK feedback information of the PDSCH received by the UE from the Scell eNB is fed back to the Scell eNB via the main Scell. In order to ensure that the HARQ-ACK feedback information would not be transmitted by the UE via two or more cells simultaneously, the HARQ-ACK feedback information of the Pcell and the HARQ-ACK feedback information of the main Scell are transmitted by Time Division Multiplexing, so that different Pcells and main Scells transmit the HARQ-ACK feedback information respectively at different time, as shown in Figure 10.

Preferably, to be compatible with the above situation 2, if both the Pcell and the main Scell work in the FDD mode, an uplink subframe for transmitting the HARQ-ACK feedback information may be the same as the uplink subframe of a cell working in the FDD mode for transmitting the HARQ-ACK feedback information in the situation 2 in which one of the Pcell and the main Scell works in the TDD mode and the other works in the FDD mode, and the timing relation of the HARQ-ACK feedback information in the situation 3 is also the same as the timing relation of the HARQ-ACK feedback information in the cell working in the FDD mode in accordance with the situation 2.

The situation 3 will be described in detail with reference with a fifth embodiment and a sixth embodiment.

In the fifth embodiment, it is supposed that the UE configures a CA system of two cells which belong to the Pcell eNB and the Scell eNB respectively. The cell belonging to the Pcell eNB is called Pcell while the cell belonging to the Scell eNB is called main Scell. Both the Pcell and the main Scell work in the FDD mode. The Pcell sends the HARQ-ACK feedback information on

subframes

9, 0, 1, 4 and 5, and the main Scell sends the HARQ-ACK feedback information on

subframe

2, 3, 7 and 8, as shown in Figure 10.

The timing relation of the HARQ-ACK feedback information of the main Scell is as follows: a subframe 9 of a radio frame n-1 and a subframe 0 of a radio frame n transmit the HARQ-ACK feedback information on a subframe 6 of the radio frame n, a subframe 1 of the radio frame n and a subframe 2 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 7 of the radio frame n, a subframe 3 of the radio frame n and a subframe 4 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 8 of the radio frame n, a subframe 5 of the radio frame n and a subframe 6 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 2 of a radio subframe n+1, and the subframe 7 of the radio frame n and the subframe 8 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 3 of the radio frame n+1, as shown in Figure 11.

As shown in Figure 12, it is supposed that there is a delta delay between the subframe 0 of the main Scell and the subframe 0 of the Pcell. If delta is 0 microsecond and subframes of the two cells are aligned, the subframe 3 and subframe 8 of the main Scell are configured by high-layer signaling to use a normal PUCCH transmission format.

If delta is 30 microseconds and subframes of the two cells are not aligned, as shown in Figure 12, the subframe 3 of the radio frame n of the main Scell is overlapped with the subframe 4 of the radio frame n of the Pcell, and the subframe 8 the radio frame n of the main Scell is also overlapped with the subframe 9 of radio frame n+1 of the Pcell. In order to avoid such overlapping of subframes, the

subframes

3 and 8 of the main Scell are configured by high-layer signaling to use a shortened PUCCH transmission format, that is, the PUCCH transmission in time slot 1 uses

OFDM symbols

0, 1, 2, 3, 4 and 5, but not OFDM symbol 6 in time slot 1, as shown in Figure 5.

In the sixth embodiment, it is supposed that the UE configures a CA system of two cells which belong to the Pcell eNB and the Scell eNB respectively. The cell belonging to the Pcell eNB is called Pcell while the cell belonging to the Scell eNB is called main Scell. Both the Pcell and the main Scell work in the FDD mode. The Pcell sends the HARQ-ACK feedback information on

subframes

9 and 4, and the main Scell sends the HARQ-ACK feedback information on

subframes

1 and 6, as shown in Figure 13.

The HARQ-ACK timing relation of the Pcell is as follows:

subframes

1, 2, 3, 4 and 5 of a radio frame n transmit the HARQ-ACK feedback information on a subframe 9 of the radio frame n, and

subframes

6, 7, 8 and 9 of the radio frame n and a subframe 0 of a radio frame n+1 transmit the HARQ-ACK feedback information on a subframe 4 of the radio frame n+1, as shown in Figure 14.

The HARQ-ACK timing relation of the main Scell is as follows:

subframes

3, 4, 5, 6 and 7 of a radio frame n transmits the HARQ-ACK feedback information on a subframe 1 of a radio frame n+1, and

subframes

8 and 9 of the radio frame n and

subframes

There is a delta delay between the subframe 0 of the radio frame n of the main Scell and the subframe 0 of the radio frame n of the Pcell. As shown in Figure 14, if the delta is 0 microsecond and subframes of the two cells are aligned, the subframe 0 and subframe 5 of the Pcell are configured by high-layer signaling to use a normal PUCCH transmission format; if the delta is 30 microseconds and subframes of the two cells are not aligned, the subframe 0 of the Pcell is not overlapped with the subframe 1 of the main Scell, and the subframe 5 of the Pcell is not overlapped with the subframe 6 of the main Scell, and the

subframes

0 and 5 of the Pcell are configured by high-layer signaling to use a normal PUCCH transmission format.

In this embodiment, as for each eNB involved in the carrier aggregation, the UE may transmit the HARQ-ACK feedback information to the eNB on at most two subframes. Thereby, the method in this embodiment is particularly applicable to the situation in which the eNBs involved in the carrier aggregation are more than 2 and less or equal to 5. In this embodiment, only the situation in which the eNBs involved in the carrier aggregation are two is described as an example. If eNBs involved in the carrier aggregation are three, a second main Scell may have one-frame interleaving with the above-mentioned Pcell and main Scell. For example, the HARQ-ACK feedback information may be transmitted on

subframes

2 and 7 of the second main Scell and a HARQ-ACK timing relation of the second main Scell may be determined according to the above-mentioned method. By way of formulas, it may be |N4-N3|=5，wherein N3 and N4 are subframes of each cell applicable to transmitting the HARQ-ACK feedback information, and N3 of each cell is different from each other. Each cell follows the HARQ-ACK timing relation that: the HARQ-ACK feedback information of the 4^th, 5^th, 6^th, 7^th and 8^th subframes before the subframe N3 is transmitted on the subframe N3, and the HARQ-ACK feedback information of the 4^th, 5^th, 6^th, 7^th and 8^th subframes before the subframe N4 is transmitted on the subframe N4.

The foregoing only describes the method of the present application. Corresponding to the method, User Equipment is also provided in the present application. As shown in Figure 15, the User Equipment includes a configuring module, a receiving module and a feedback module.

The configuring module is adapted to configure the UE to work in an Inter-eNB carrier aggregation mode according to configuration information received from a Pcell eNB.

The receiving module is adapted to receive PDCCH and PDSCH data respectively from each cell of the Pcell eNB and each cell of a Scell eNB.

The feedback module is adapted to transmit HARQ-ACK feedback information of the PDSCH data received from each cell of the Pcell eNB to the Pcell eNB, and transmit HARQ-ACK feedback information of the PDSCH data received from each cell of the Scell eNB to the Scell eNB.

As can be seen from the above, according to the method and UE for transmitting HARQ-ACK feedback information in the Inter-eNB carrier aggregation system, HARQ-ACK feedback information of different eNBs can be transmitted respectively in the Inter-eNB carrier aggregation system due to relevant configurations at both the base station side and the UE side.

The foregoing is only embodiments of the present invention. The protection scope of the present invention, however, is not limited to the above description. Any change or substitution, easily occurring to those skilled in the art, should be covered by the protection scope of the present invention.

Claims

A method for transmitting Hybrid Automatic Repeat-Request Acknowledgement (HARQ-ACK) feedback information in an Inter-eNB Carrier Aggregation (Inter-eNB CA) system, comprising:

receiving, by User Equipment (UE), configuration information from a Primary cell eNB (Pcell eNB), the configuration information configuring the UE to work in an Inter-eNB CA mode;

receiving, by the UE, Physical Downlink Shared Channel (PDSCH) data from each cell involved in Inter-eNB carrier aggregation; and

sending, by the UE, HARQ-ACK feedback information of the PDSCH data received from each cell of the Pcell eNB to the Pcell eNB, and sending, by the UE, HARQ-ACK feedback information of the PDSCH data received from each cell of each Secondary cell Scell eNB to a corresponding Scell eNB via a Scell designated by the corresponding Scell eNB.
The method of claim 1, wherein

the Pcell and a Scell designated by each Scell eNB work in a Time Division Duplex (TDD) mode;

wherein the UE receives the PDSCH data of each cell sent by the Pcell eNB on a subframe k, and receives the PDSCH data of each cell sent by a Scell eNB c on a subframe |k-Nc|, wherein k represents a sequence number of a subframe, c represents a sequence number of a Scell eNB, Nc represents a subframe offset between downlink transmission of each Scell eNB and the Pcell eNB, Nc is a natural number and Nc for each Scell eNB involved in the Inter-eNB carrier aggregation is different from each other.
The method of claim 2,

wherein eNBs involved in the Inter-eNB carrier aggregation are one Pcell eNB and one Scell eNB; wherein the method further comprises: transmitting, by the Pcell and a Scell designated by the Scell eNB, the HARQ-ACK feedback information on one or more subframes of subframes 2, 3, 7 and 8;

if TDD uplink and downlink configurations of the Pcell or the Scell designated by the Scell eNB are 1, 2, 4 and 5, a HARQ-ACK timing relation of the Pcell or the Scell designated by the Scell eNB follows a HARQ-ACK relation of the TDD uplink and downlink configurations of the Pcell or the Scell designated by the Scell eNB; if the TDD uplink and downlink configurations of the Pcell or the Scell designated by the Scell eNB are 3, the HARQ-ACK timing relation of the Pcell or the Scell designated by the Scell eNB follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 4; if the TDD uplink and downlink configurations of the Pcell or the Scell designated by the Scell eNB are 0 and 6, the HARQ-ACK timing relation of the Pcell or the Scell designated by the Scell eNB follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 1.
The method of claim 2,

wherein eNBs involved in the Inter-eNB carrier aggregation are one Pcell eNB and one to four Scell eNBs; wherein the method further comprises: transmitting, by the Pcell and a Scell designated by each Scell eNB, the HARQ-ACK feedback information on one or more of subframes 2 and 7;

if TDD uplink and downlink configurations of the Pcell or the Scell designated by said each Scell eNB are 0, 1, 2 and 6, a HARQ-ACK timing relation of the Pcell or the Scell designated by said each Scell eNB follows a HARQ-ACK timing relation of the TDD uplink and downlink configurations which are 2; if the TDD uplink and downlink configurations of the Pcell or the Scell designated by each Scell eNB are 3, 4 and 5, the HARQ-ACK timing relation of the Pcell or the Scell designated by said each Scell eNB follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 5.
The method of claim 1,

wherein at least one of the Pcell and a Scell designated by each Scell eNB work in a Time Division Duplex (TDD) mode, and at least one of the Pcell and the Scell designated by said each Scell eNB work in a Frequency Division Duplex (FDD) mode;

wherein the UE transmits the HARQ-ACK feedback information of the Pcell and the Scell designated by said each Scell eNB on different subframes.
The method of claim 5,

wherein eNBs involved in the Inter-eNB carrier aggregation are one Pcell eNB and one Scell eNB; wherein a cell working in the TDD mode of the Pcell and a Scell designated by the Scell eNB transmits the HARQ-ACK feedback information on one or more of subframes 2, 3, 7 and 8, and wherein a cell working in the FDD mode of the Pcell and a Scell designated by the Scell eNB transmits the HARQ-ACK feedback information on one or more of subframes 9, 0, 1 4 and 5;

wherein, if TDD uplink and downlink configurations of the cell working in the TDD mode are 1, 2, 4 and 5, a HARQ-ACK timing relation of the cell working in the TDD mode follows a HARQ-ACK relation of the TDD uplink and downlink configurations of the cell working in the TDD mode; if the TDD uplink and downlink configurations of the cell working in the TDD mode are 3, the HARQ-ACK timing relation of the cell working in the TDD mode follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 4; if the TDD uplink and downlink configurations of the cell working in the TDD mode are 0 and 6, the HARQ-ACK timing relation of the cell working in the TDD mode follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 1; and

a timing relation of the cell working in the FDD mode is that: a subframe 8 of a radio frame n-1 of the cell working in the FDD mode and a subframe 9 of the radio frame n-1 of the cell working in the FDD mode transmit the HARQ-ACK feedback information on a subframe 4 of a radio frame n, a subframe 0 of the radio frame n and a subframe 1 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 5 of the radio frame n, a subframe 2 of the radio frame n and a subframe 3 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 9 of the radio frame n, the subframe 4 of the radio frame n and the subframe 5 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 0 of a radio subframe n+1, and a subframe 6 of the radio frame n and a subframe 7 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 1 of the radio frame n+1.
The method of claim 5,

wherein eNBs involved in the Inter-eNB carrier aggregation are one Pcell eNB and one to four Scell eNBs; wherein a cell working in the TDD mode of the Pcell and a Scell designated by each Scell eNB transmits the HARQ-ACK feedback information on one or more of subframes 2 and 7, and a cell working in the FDD mode of the Pcell and the Scell designated by said each Scell eNB transmits the HARQ-ACK feedback information on subframes N1 and N2, wherein |N2-N1|=5，N1≠2, and N1 of each cell is different from each other;

if TDD uplink and downlink configurations of the cell working in the TDD mode are 0, 1, 2 and 6, a HARQ-ACK timing relation of the cell working in the TDD mode follows a HARQ-ACK timing relation of the TDD uplink and downlink configurations which are 2; if the TDD uplink and downlink configurations of the cell working in the TDD mode are 3, 4 and 5, the HARQ-ACK timing relation of the cell working in the TDD mode follows a HARQ-ACK timing relation of the TDD uplink and downlink configuration 5; and

wherein the cell working in the FDD mode follows a HARQ-ACK timing relation that HARQ-ACK feedback information of the 4^th, 5^th, 6^th, 7^th and 8^th subframes before the subframe N1 is transmitted on the subframe N1, and that HARQ-ACK feedback information of the 4^th, 5^th, 6^th, 7^th and 8^th subframes before the subframe N2 is transmitted on the subframe N2.
The method of claim 1,

wherein the Pcell and a Scell designated by each Scell eNB work in a Frequency Division Duplex (FDD) mode;

wherein the UE transmits the HARQ-ACK feedback information of the Pcell and the Scell designated by said each Scell eNB on different subframes.
The method of claim 8,

wherein eNBs involved in the Inter-eNB carrier aggregation are one Pcell eNB and one Scell eNB;

wherein one cell of the Pcell and a Scell designated by the Scell eNB transmits the HARQ-ACK feedback information on subframes 2, 3, 6, 7 and 8, and another cell transmits the HARQ-ACK feedback information on subframes 9, 0, 1, 4 and 5;

wherein the one cell follows a HARQ-ACK timing relation that: a subframe 9 of a radio frame n-1 and a subframe 0 of a radio frame n transmit the HARQ-ACK feedback information on a subframe 6 of the radio frame n, a subframe 1 of the radio frame n and a subframe 2 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 7 of the radio frame n, a subframe 3 of the radio frame n and a subframe 4 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 8 of the radio frame n, a subframe 5 of the radio frame n and a subframe 6 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 2 of a radio subframe n+1, and the subframe 7 of the radio frame n and the subframe 8 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 3 of the radio frame n+1;

wherein said another cell follows a HARQ-ACK timing relation that: a subframe 8 of a radio frame n-1 and a subframe 9 of the radio frame n-1 transmit the HARQ-ACK feedback information on a subframe 4 of a radio frame n, a subframe 0 of the radio frame n and a subframe 1 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 5 of the radio frame n, a subframe 2 of the radio frame n and a subframe 3 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 9 of a radio frame n+1, the subframe 4 of the radio frame n and the subframe 5 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 0 of the radio subframe n+1, and a subframe 6 of the radio frame n and a subframe 7 of the radio frame n transmit the HARQ-ACK feedback information on a subframe 1 of the radio frame n+1.
The method of claim 8,

wherein eNBs involved in the Inter-eNB carrier aggregation are one Pcell eNB and one to four Scell eNBs;

wherein the Pcell and a Scell designated by each Scell eNB transmits the HARQ-ACK feedback information on subframes N3 and N4, wherein |N4-N3|=5，wherein N3 of each cell is different from each other;

wherein HARQ-ACK feedback information of the 4^th, 5^th, 6^th, 7^th and 8^th subframes before the subframe N3 is transmitted on the subframe N3, and HARQ-ACK feedback information of the 4^th, 5^th, 6^th, 7^th and 8^th subframes before the subframe N4 is transmitted on the subframe N4.
The method of any of claims 1-10, wherein

if two subframes of different cells for transmitting the HARQ-ACK feedback information are overlapped with each other, a first subframe of the two subframes uses a shortened Physical Uplink Control Channel (PUCCH) transmission format if tail of the first subframe is overlapped with head of a second subframe of the two subframes.
User Equipment (UE), applicable to transmitting Hybrid Automatic Repeat-Request Acknowledgement (HARQ-ACK) feedback information in an Inter-eNB Carrier Aggregation (Inter-eNB CA) system, comprising:

a configuring module, adapted to configure the UE to work in an Inter-eNB carrier aggregation mode according to configuration information received from a Primary cell (Pcell) eNB;

a receiving module, adapted to receive Physical Downlink Shared Channel (PDSCH) data from each cell involved in Inter-eNB carrier aggregation;

a feedback module, adapted to transmit HARQ-ACK feedback information of the PDSCH data received from each cell of the Pcell eNB to the Pcell eNB, and transmit HARQ-ACK feedback information of the PDSCH data received from each cell of each Secondary cell (Scell) eNB to a corresponding Scell eNB via a Scell designated by the corresponding Scell eNB.