WO2013165199A1

WO2013165199A1 - Method for maintaining transmission continuity of uplink harq process in dynamic tdd system

Info

Publication number: WO2013165199A1
Application number: PCT/KR2013/003821
Authority: WO
Inventors: Shichang Zhang; Yingyang Li; Chengjun Sun
Original assignee: Samsung Electronics Co., Ltd.; Beijing Samsung Telecom R&D Center
Priority date: 2012-05-02
Filing date: 2013-05-02
Publication date: 2013-11-07
Also published as: KR20130123331A; CN103384192A

Abstract

An embodiment of the present invention provides a method for maintaining transmission continuity of an uplink Hybrid Automatic Repeat Request (HARQ) process in a dynamic Time Division Duplexing (TDD) system. The method includes: after sending a Physical Uplink Shared Channel (PUSCH), determining, by a User Equipment (UE), location of a next scheduling command corresponding to the uplink HARQ process of the PUSCH; detecting, by the UE, an uplink scheduling command at the determined location; processing, by the UE, retransmission of the uplink HARQ process or transmission of a new uplink HARQ process at a corresponding uplink subframe, according to the received uplink scheduling command. Thus, an uplink HARQ process before the change of TDD Uplink Downlink (UL-DL) configuration may be enabled to transit to a TDD UL-DL configuration after change, so as to maintain the transmission continuity of an uplink HARQ process.

Description

METHOD FOR MAINTAINING TRANSMISSION CONTINUITY OF UPLINK HARQ PROCESS IN DYNAMIC TDD SYSTEM

The present invention relates to mobile communications technologies, and more particularly, to a method for maintaining transmission continuity of an uplink Hybrid Automatic Repeat Request (HARQ) process in a dynamic Time Division Duplexing (TDD) system.

Long Term Evolution (LTE) system supports two duplex modes, that is, Frequency Division Duplexing (FDD) and TDD. FIG.1 is a schematic diagram illustrating a frame structure in a TDD system of the LTE. Length of each radio frame is 10ms, which is divided into two half-frames. Length of each half-frame is 5ms. Each half-frame includes 8 time slots and 3 special domains. Length of each time slot is 0.5ms. Total length of the 3 special domains is 1ms. The 3 special domains refer to Downlink Pilot Time Slot (DwPTS), Guard Period (GP) and Uplink Pilot Time Slot (UpPTS). Each subframe consists of two consecutive time slots.

Transmission in the TDD system includes: transmission from an evolved Node B (eNB) to a User Equipment (UE) (refer to as downlink), and transmission from a UE to an eNB (refer to as uplink). Based on the frame structure shown in FIG.1, 10 subframes are shared by uplink and downlink every time period of 10 ms. Each subframe may be allocated to the uplink or the downlink. A subframe allocated to the uplink may be referred to as an uplink subframe. A subframe allocated to the downlink may be referred to as a downlink subframe. A TDD system may support 7 kinds of Uplink-Downlink (UL-DL) configurations, as shown in Table 1. In Table 1, D represents a downlink subframe, U represents an uplink subframe, and S represents a special subframe which includes 3 special domains mentioned above.

Table 1

Table 1 TDD UL-DL configuration table

The TDD system in the LTE supports the HARQ mechanism. Fundamental theory of the HARQ mechanism includes the following. An eNB allocates uplink resources for a UE; the UE sends uplink data to the eNB with the uplink resources; the eNB receives the uplink data, and sends HARQ indication information to the UE. And then, the UE may retransmit the uplink data, based on the indication information. Specifically speaking, the UE may enable a Physical Uplink Shared Channel (PUSCH) to bear the uplink data. The eNB may enable a Physical Downlink Control Channel (PDCCH) to bear scheduling and control information of the PUSCH, that is, Uplink Grant (UL Grant). The eNB may enable a Physical Hybrid Automatic Repeat Request (HARQ) Indicator Channel (PHICH) to bear the HARQ indication information. In above process, a pre-configured timing relationship may be employed to determine time position for a transmission of the PUSCH and time position for a subsequent retransmission. The pre-configured timing relationship includes a timing relationship from UL Grant to PUSCH, a timing relationship from PHICH to PUSCH, and a timing relationship from PUSCH to PHICH. In the following, the foregoing three timing relationships may be referred to as PUSCH synchronization HARQ timing relationship.

Firstly, a timing relationship from the UL Grant or PHICH to the PUSCH in existing LTE is introduced.

For the timing relationship from the UL Grant to the PUSCH, suppose the UE receives the UL Grant at the downlink subframe n (n is sequence number of subframe index, similarly hereinafter), the UL Grant is in charge of controlling the PUSCH within uplink subframe (n+k). Here, the value of k is defined in Table 2. Specifically speaking, regarding TDD UL-DL configurations (or refer to as UL-DL configuration for short) 1~6, number of uplink subframes is smaller than or equal to number of downlink subframes (S frame may be used as a downlink subframe). For any downlink subframe n, a unique PUSCH synchronization HARQ timing relationship may be configured with a unique k value, which is reflected in Table 2. The PUSCH may not be scheduled within a downlink subframe. Alternatively, only the PUSCH within an uplink subframe may be scheduled within a downlink subframe. While, regarding TDD UL-DL configuration 0, number of uplink subframes is larger than number of downlink subframes. It is necessary for the PDCCH of each downlink subframe to schedule the PUSCH in two uplink subframes. Thus, value of k cannot be unique. It is necessary for the PDCCH to employ UL index technologies to support scheduling of the PUSCH in two uplink subframes. For PUSCH with different indexes, different k values may be employed. For example, when the UE receives the PDCCH at downlink subframe 0, the PUSCH within uplink subframe 4 is scheduled, and/or, the PUSCH within uplink subframe 7 is scheduled. When the UE receives the PDCCH at downlink subframe 1, the PUSCH within uplink subframe 7 is scheduled, and/or, the PUSCH within uplink subframe 8 is scheduled.

For the timing relationship from the PHICH to the PUSCH, in existing LTE, PHICH resource set is allocated independently to the PUSCH within each uplink subframe. Suppose the UE receives the PHICH at downlink subframe n, the PHICH may be used for indicating HARQ-ACK information of the PUSCH about uplink subframe (n+j). Value of j is defined in Table 2. Specifically speaking, for the TDD UL-DL configurations 1~6, number of uplink subframes is smaller than or equal to number of downlink subframes. For any downlink subframe n, a unique PUSCH synchronization HARQ timing relationship may be configured with a unique j value, which is reflected in Table 2. The PHICH resource set may not be configured within a downlink subframe. Alternatively, only the PHICH resource set of an uplink subframe may be configured within a downlink subframe. Regarding TDD UL-DL configuration 0, number of uplink subframes is larger than number of downlink subframes. Subsequently, value of j is not unique. Instead, two PHICH resource sets, that is, PHICH resource 0 and PHICH resource 1, may be respectively configured for

downlink subframes

0 and 5. Regarding different PHICH resources, different j values may be employed. For example, when the UE receives the PHICH at downlink subframe 0, the PUSCH within uplink subframe 4, and/or, the PUSCH within uplink subframe 7 may be triggered.

Table 2

Table 2 a timing relationship table from UL-Grant/PHICH to PUSCH

Secondly, the timing relationship from the PUSCH to the PHICH in the existing LTE is introduced.

For TDD UL-DL configurations 1~6, when the UE receives the PHICH within downlink subframe n, the PHICH may indicate the HARQ-ACK information of PUSCH within uplink subframe (n-h). Value of h is shown in Table 3.

For TDD UL-DL configuration 0, since two PHICH resources are configured, when the UE receives the PHICH at PHICH resource 0 within downlink subframe n, the PHICH may indicate the HARQ-ACK information of PUSCH within uplink subframe (n-h), based on definition about h in Table 3. While, when the UE receives the PHICH at PHICH resource 1 of downlink subframe 0 or downlink subframe 5, the PHICH may indicate the HARQ-ACK information transmitted by the PUSCH within uplink subframe (n-6).

Table 3

Table 3 a timing relationship table from PUSCH to PHICH

Based on tables (Tables 2 and 3) about foregoing 3 timing relationships, a PUSCH synchronization HARQ timing relationship may be determined, when a Cell employs a certain TDD UL-DL configuration. Subsequently, synchronous transmission of the PUSCH may be implemented, according to the PUSCH synchronization HARQ timing relationship.

With the improvement about requirements to data transmission speed put forward by a user, people also propose LTE-Advanced (LTE-A) technologies. In the LTE-A, it may enable a ratio of current uplink subframe to current downlink subframe to be more in line with a ratio of current uplink service amount to current downlink service amount, by using dynamic TDD technologies, that is, by using physical layer signaling to set UL-DL configurations for a TDD system, so as to facilitate improvement of UL-DL peak rate about a user, and improvement of throughput capacity of a system.

For a dynamic TDD system, the TDD UL-DL configuration of a cell may dynamically change, accompanying with UL-DL service amount within current cell. After the TDD UL-DL configuration of the cell changes, the HARQ-ACK indication of the PUSCH, which corresponds to some uplink HARQ processes with original TDD UL-DL configuration, may not be sent with a new TDD UL-DL configuration. In this case, it may lead to non-adaptive retransmission of the some uplink HARQ processes mentioned above. Subsequently, uplink rate of the user and uplink throughput capacity of the whole system may be affected. Thus, it is necessary to put forward a corresponding technical solution, which is also effective, so as to implement retransmission indication or indication about a new transmission for an uplink HARQ process, when the TDD UL-DL configuration changes. Subsequently, transmissions about these uplink HARQ processes may be continuous.

The present invention provides a method for maintaining transmission continuity of an uplink HARQ process in a dynamic TDD system, so as to guarantee transmission continuity of the uplink HARQ process, when the TDD UL-DL configuration changes dynamically.

An embodiment of the present invention provides a method for maintaining transmission continuity of an uplink Hybrid Automatic Repeat Request (HARQ) process in a Time Division Duplexing (TDD) system, including:

A, after sending a Physical Uplink Shared Channel (PUSCH), determining, by a User Equipment (UE), location of a next scheduling command corresponding to the uplink HARQ process of the PUSCH;

B, detecting, by the UE, an uplink scheduling command at the determined location;

C, processing, by the UE, retransmission of the uplink HARQ process or transmission of a new uplink HARQ process at a corresponding uplink subframe, according to the received uplink scheduling command.

Preferably, determining by the UE the location of the next scheduling command corresponding to the uplink HARQ process of the PUSCH in A includes:

determining, by the UE, location of the uplink subframe located by a next transmission, which corresponds to the uplink HARQ process of the PUSCH, according to current PUSCH synchronization HARQ timing relationship;

taking, by the UE, all of the possible locations where the uplink scheduling command of the uplink subframe appears, as the location of the next scheduling command, under the circumstances of all of the PUSCH synchronization HARQ timing relationships and based on the location of the uplink subframe.

Preferably, the uplink scheduling command includes a Physical Hybrid-Automatic Repeat Request (HARQ) Indicator Channel (PHICH), and/or, an uplink Grant (UL-Grant); and B includes:

for the PHICH, detecting the PHICH at a PHICH location corresponding to the PUSCH, according to current PUSCH synchronization HARQ timing relationship;

for the UL-Grant, detecting the UL-Grant at subframe

based on Table 4;

[Table 4]

wherein,

is a subframe number of the uplink subframe located by the next transmission.

Preferably, the method further includes:

when the UE detects the UL-Grant at subframe

, and determines that the PUSCH synchronization HARQ timing relationship changes according to the UL-Grant, adjusting, by the UE, current PUSCH synchronization HARQ timing relationship to a PUSCH synchronization HARQ timing relationship corresponding to the UL-Grant.

taking, by the UE, all of the possible locations where the uplink scheduling command corresponding to the PUSCH appears, as the location of the next scheduling command, under the circumstances of all of the PUSCH synchronization HARQ timing relationships and based on the location of the PUSCH.

for the UL-Grant, detecting the UL-Grant at subframe n+k based on Table 5;

[Table 5]

wherein n is a subframe number located by the PUSCH.

Preferably, the uplink scheduling command includes a PHICH, and/or, a UL-Grant; and B includes:

for the UL-Grant, detecting the UL-Grant at subframe n+k based on Table 6;

[Table 6]

wherein n is a subframe number located by the PUSCH.

for the UL-Grant, detecting the UL-Grant at subframe n+k based on Table 7;

[Table 7]

wherein n is a subframe number located by the PUSCH.

Preferably, the method further includes:

when the UE detects the UL-Grant at subframe n+k, and determines that the PUSCH synchronization HARQ timing relationship changes based on the UL-Grant, adjusting, by the UE, current PUSCH synchronization HARQ timing relationship to a PUSCH synchronization HARQ timing relationship corresponding to the UL-Grant.

Based on above technical solution provided by embodiments of the present invention, it can be seen that, each time after a UE sending PUSCH, detect a scheduling command from all of the possible locations of a next scheduling command, which corresponds to the uplink HARQ process about the PUSCH. After receiving an uplink scheduling command, process the retransmission of the uplink HARQ process, or process transmission about a new uplink HARQ process, at a corresponding uplink subframe, according to contents about the uplink scheduling command. Thus, take a first scheduling command of the uplink HARQ process in the changed PUSCH synchronization HARQ timing relationship as a bridge, connect the uplink HARQ process in the previous PUSCH synchronization HARQ timing relationship with the uplink HARQ process in the changed PUSCH synchronization HARQ timing relationship. Thus, it enables the uplink HARQ process in the previous TDD UL-DL configuration to be transited to the changed TDD UL-DL configuration. And, transmission continuity of the uplink HARQ process may be maintained.

Apply the technical solution provided by embodiments of the present invention to a dynamic TDD system, so as to effectively manage PUSCH transmission. Furthermore, modification to the existing system is small, which will not affect system compatibility. Besides, the implementation thereof is simple and efficient.

FIG.1 is a schematic diagram illustrating a frame structure in a TDD system of the LTE.

FIG.2 is a flowchart illustrating a method, in accordance with an embodiment of the present invention.

FIG.3 is a flowchart illustrating a method, in accordance with a first embodiment of the present invention.

FIG.4 is a schematic diagram illustrating a specific implementation scenario about a first example, in accordance with a first embodiment of the present invention.

FIG.5 is a schematic diagram illustrating a specific implementation scenario about a second example, in accordance with the first embodiment of the present invention.

FIG.6 is a flowchart illustrating a method, in accordance with a second embodiment of the present invention.

FIG.7 is a schematic diagram illustrating a specific implementation scenario about a first example, in accordance with a second embodiment of the present invention.

FIG.8 is a schematic diagram illustrating a specific implementation scenario about a second example, in accordance with the second embodiment of the present invention.

FIG.9 is a schematic diagram illustrating a UE, in accordance with an embodiment of the present invention.

To make objectives, technical solutions and advantages of the present invention more clear, detailed descriptions about the present invention will be provided in the following, accompanying with attached figures and embodiments.

Embodiments of the present invention mainly aim at a dynamic TDD scenario. In this scenario, the TDD UL-DL configuration of a cell may change, accompanying with dynamic change of UL-DL service amount within current cell. To guarantee continuity of an uplink HARQ process before and after the change of TDD UL-DL configuration to the largest extent, an embodiment of the present invention provides a method for maintaining transmission continuity about an uplink HARQ process.

In the method provided by an embodiment of the present invention, take a first scheduling command about an uplink HARQ process in the changed PUSCH synchronization HARQ timing relationship as a bridge, connect an uplink HARQ process in the PUSCH synchronization HARQ timing relationship before the change with the uplink HARQ process in the changed PUSCH synchronization HARQ timing relationship. That is, each time after a UE sending the PUSCH, determine all of the possible locations about a next scheduling command, which corresponds to the uplink HARQ process of the PUSCH, with a certain mode. And, detect the scheduling command from all of the possible locations. After receiving the scheduling command, process the retransmission about the uplink HARQ process, or process transmission about a new uplink HARQ process, at a corresponding uplink subframe, according to the contents in the scheduling command. Determine current PUSCH synchronization HARQ timing relationship once again. Thus, it may enable an uplink HARQ process in a TDD UL-DL configuration before the change to be transited to a changed TDD UL-DL configuration. Subsequently, transmission continuity about an uplink HARQ process may be maintained, as shown in FIG.2, which includes the following blocks.

Referring to fig.2, Block 201: after sending PUSCH, a UE may determine location of a next scheduling command, which corresponds to an uplink HARQ process about the PUSCH, according to a certain rule.

Block 202: the UE detects an uplink scheduling command from the location determined in block 201.

Block 203: the UE processes retransmission of the uplink HARQ process, or processes transmission of a new uplink HARQ process, at a corresponding uplink subframe, according to the received uplink scheduling command. When necessary, the UE may convert current PUSCH synchronization HARQ timing relationship into another PUSCH synchronization HARQ timing relation latest indicated by the eNB.

Detailed descriptions about the present invention will be provided in the following, accompanying with two specific embodiments.

a first embodiment

In the embodiment, each time after a UE sending PUSCH, determine an uplink subframe (hereinafter referred to as

) located by a next transmission, which corresponds to the uplink HARQ process (hereinafter referred to as

) of the PUSCH, according to current PUSCH synchronization HARQ timing relationship (hereinafter referred to as

). Take an uplink scheduling command about

subsequently received as a next scheduling command about

. Here, suppose

in the changed TDD UL-DL configuration is not an uplink subframe, and

has been processed correspondingly by the eNB. That is, all of the

involved in embodiments of the present invention is an uplink subframe.

Specific implementation blocks are as follows.

Referring to FIG.3, 110, after sending PUSCH, a UE may determine an uplink subframe location

located by a next transmission, which corresponds to an uplink HARQ process Pc about the PUSCH, according to current PUSCH synchronization HARQ timing relationship

.

When

corresponds to an uplink Round Trip Time (RTT) of 10ms,

is a subframe same as the next system frame. When

corresponds to an uplink RTT, which is not 10ms, it is necessary to firstly determine location of PHICH, and/or, UL-Grant, according to

, in which the PHICH and UL-Grant correspond to

. And then, determine NUlNext, based on

as well as location of the PHICH, and/or, UL-Grant.

120, when a PUSCH synchronization HARQ timing relationship of a system frame located by NUlNext is the same as current PUSCH synchronization HARQ timing relationship, the eNB may send the PHICH, and/or, HL-Grant, according to requirements of existing LTE/LTE-A. When the PUSCH synchronization HARQ timing relationship of the system frame located by

is different from current PUSCH synchronization HARQ timing relationship, the eNB needs to determine the UL-Grant location corresponding to

, based on a new PUSCH synchronization HARQ timing relationship (that is, the PUSCH synchronization HARQ timing relationship of the system frame located by

). And then, the eNB may send a UL-Grant scheduling

at the UL-Grant location, and inform the UE about the new PUSCH synchronization HARQ timing relationship.

Here, the eNB needs to execute operations in block 110 like the UE, and determines

of next sending location about data of the uplink HARQ process. When the PHICH corresponding to

based on

is still a downlink subframe, the eNB may send the PHICH, and/or, UL-Grant at the location of the PHICH, based on requirements and receiving conditions about Pc (receive correctly/receive incorrectly).

The eNB may inform the UE about the PUSCH synchronization HARQ timing relationship corresponding to the UL-Grant, by using location of a downlink subframe located by the UL-Grant, and/or, state of some bits in the UL-Grant.

130, the UE may detect an uplink scheduling command from all of the possible locations, where an uplink scheduling command about

may appear.

Here, the uplink scheduling command includes the PHICH, and/or, UL-Grant. Regarding the PHICH, the UE only needs to detect the PHICH for

, according to the PHICH location corresponding to

. While, regarding the UL-Grant, the UE needs to detect the UL-Grant at the location of subframe

. The relationship between k and

is shown in Table 4. Table 4 shows all of the possible locations, where the UL-Grant may appear, in all of the PUSCH synchronization HARQ timing relationships, in which all of the possible locations are obtained by performing reverse-reasoning on Table 2.

Table 4

140, the UE processes retransmission of

at

, according to the received scheduling command, or processes transmission of a new uplink HARQ process. When the UE received the UL-Grant about

, and determines that the PUSCH synchronization HARQ timing relationship is changed, according to the UL-Grant. And then, the UE may adjust current PUSCH synchronization HARQ timing relationship to a PUSCH synchronization HARQ timing relationship corresponding to the UL-Grant; otherwise, the UE may maintain current PUSCH synchronization HARQ timing relationship.

The UE may determine the PUSCH synchronization HARQ timing relationship corresponding to the UL-Grant, by using location of a downlink subframe located by the detected UL-Grant, and/or, by using states of some bits in the UL-Grant.

Detailed descriptions about embodiments of the present invention are further provided in the following, accompanying with FIG.3 and FIG.4, which illustrate two specific examples.

A first example

As shown in FIG.4, in the first example, a first system frame employs TDD UL-DL configuration 0, and a second system frame employs TDD UL-DL configuration 2.

Based on 110, after sending the PUSCH at subframe 4 of the first system frame, a UE may determine location of a next sending corresponding to an uplink HARQ process of the PUSCH, which is subframe 7 of the second system frame, according to the PUSCH synchronization HARQ timing relationship of current TDD UL-DL configuration 0.

Since the eNB needs to change the TDD UL-DL configuration in the second system frame into TDD UL-DL configuration 2, based on the PUSCH synchronization HARQ timing relationship shown in Table 2, the UL-Grant of scheduling subframe 7 with the TDD UL-DL configuration 2 should be sent at subframe 3. Thus, the eNB needs to send the UL-Grant to schedule subframe 7 of the second system frame, at subframe 3 of the second system frame, and informs the UE about the new PUSCH synchronization HARQ timing relationship.

Meanwhile, based on the timing relationship from the PUSCH to the PHICH with the TDD UL-DL configuration 0, the PHICH of subframe 4 should be sent at subframe 0 of a next system frame. While, in the example, subframe 0 of a next system frame of the first system frame (that is, a second system frame) is still a downlink subframe. Thus, the eNB may still send the PHICH of subframe 4 of the first system frame at subframe 0 of the second system frame, according to the PUSCH synchronization HARQ timing relationship with the TDD UL-DL configuration 0.

Based on 130, the UE needs to detect the PHICH of subframe 4 of the first system frame, at subframe 0 of the second system frame, and detects the UL-Grant of subframe 7 of the second system frame at

subframes

0, 1 and 3 of the second system frame, according to Table 4. Since subframe 0 of the second system frame is still a downlink subframe, the UE may detect the PHICH. Meanwhile, when correctly receiving the UL-Grant of subframe 3 of the second system frame, the UE needs to process retransmission of an uplink HARQ process about subframe 4 of the first system frame, or process transmission of a new uplink HARQ process, at subframe 7 of the second system frame, according to indication of the received UL-Grant. The UE needs to change current PUSCH synchronization HARQ timing relationship into a PUSCH synchronization HARQ timing relationship corresponding to TDD UL-DL configuration 2.

A second example

As shown in FIG.5, in the second example, a first system frame employs TDD UL-DL configuration 1, while a second system frame employs TDD UL-DL configuration 0.

Based on 110, after sending the PUSCH at subframe 8 of the first system frame, the UE may determine that location of a next sending corresponding to an uplink HARQ process about the PUSCH is subframe 8 of the second system frame, according to the PUSCH synchronization HARQ timing relationship of current TDD UL-DL configuration 1.

Since the eNB needs to modify the TDD UL-DL configuration in the second system frame to TDD UL-DL configuration 0, based on the PUSCH synchronization HARQ timing relationship shown in Table 2, the UL-Grant to schedule subframe 8 should be sent at subframe 1 with TDD UL-DL configuration 0. Thus, the eNB needs to send the UL-Grant to schedule subframe 8 of the second system frame, at subframe 1 of the second system frame, and needs to inform the UE about the new PUSCH synchronization HARQ timing relationship.

Meanwhile, the PHICH of subframe 8 should be sent at subframe 4 of a next system frame, according to the timing relationship from the PUSCH to the PHICH with TDD UL-DL configuration 1. While, in the example, subframe 4 of a next system frame about the first system frame (that is, the second system frame) is an uplink subframe, which cannot send the PHICH. Thus, the eNB may not send the PHICH for subframe 8 of the first system frame.

Based on 130, the UE should detect the PHICH of subframe 8 of the first system frame at subframe 4 of the second system frame, and detect the UL-Grant of subframe 8 of the second system frame at

subframes

4 and 1 of the second system frame, according to Table 4. Since subframe 4 of the second system frame has already become an uplink subframe, the UE cannot detect the PHICH. However, the UE may detect the UL-Grant at subframe 1 of the second system frame. At this time, the UE needs to process retransmission of an uplink HARQ process about subframe 8 of the first system frame, or process transmission of a new uplink HARQ process, at subframe 8 of the second system frame, according to indication of the received UL-Grant. The UE also modifies current PUSCH synchronization HARQ timing relationship to a PUSCH synchronization HARQ timing relationship corresponding to TDD UL-DL configuration 0.

A second embodiment

In the second embodiment, each time after a UE sending PUSCH, the UE may detect an uplink scheduling command from all of the possible locations. When detecting an uplink scheduling command, and the PUSCH synchronization HARQ timing relationship determined based on the uplink scheduling command may correspond to the PUSCH, determine the uplink scheduling command to be a next scheduling command of the PUSCH. The specific blocks are as follows.

Referring to FIG.6, 210, after sending the PUSCH at uplink subframe n, the UE may detect the PHICH at a corresponding location, according to current PUSCH synchronization HARQ timing relationship Tc. The UE may detect the UL-Grant from all of the possible locations (n+k).

Here, value of k is relevant with sending location n of the PUSCH. When maintaining all of the PUSCH synchronization HARQ timing relationships about all of the TDD UL-DL configurations defined by current LTE/LTE-A, the relationship between n and k is shown in Table 5. Table 5 shows all of the possible locations where UL-Grant may appear, in which all of the possible locations are obtained by performing reverse-reasoning on Table 3.

Table 5

An improved technical solution is as follows. Since an uplink subframe of TDD UL-DL configuration 2 defined by existing LTE/LTE-A is a subnet of that of TDD UL-DL configuration 1, and an uplink RTT of each of them is 10ms. Thus, in the dynamic TDD, the PUSCH synchronization HARQ timing relationship of TDD UL-DL configuration 2 may be replaced with PUSCH synchronization HARQ timing relationship of TDD UL-DL configuration 1. Similarly, the PUSCH synchronization HARQ timing relations of TDD UL-

DL configurations

4 and 5 may be replaced with PUSCH synchronization HARQ timing relationship of TDD UL-DL configuration 3. Thus, take into account all of the locations where the UL-Grant may be detected, it may only reserve the PUSCH synchronization HARQ timing relationships of TDD UL-

DL configurations

0, 1, 3, 6 defined by current LTE/LTE-A. Subsequently, the relationship between n and k is shown in Table 6. Compared with Table 5, locations to be detected by the UE for the UL-Grant in Table 6 are reduced.

Table 6

Based on Table 6, when further limit that, the location for sending scheduling indication. Thus, locations to be detected by the UE for UL-Grant may be further reduced, as shown in Table 7.

Table 7

220, when a PUSCH synchronization HARQ timing relationship of a next system frame is the same as current PUSCH synchronization HARQ timing relationship, the eNB may send the PHICH, and/or, the UL-Grant, according to requirements of existing LTE/LTE-A. When the PUSCH synchronization HARQ timing relationship of the next system frame is different from current PUSCH synchronization HARQ timing relationship, the eNB needs to send the UL-Grant at (n+k), according to the new PUSCH synchronization HARQ timing relationship, and inform the UE about the new PUSCH synchronization HARQ timing relationship.

Here, the value of k may be determined by the eNB, based on the new PUSCH synchronization HARQ timing relationship and Table 3. The eNB may inform the UE about the PUSCH synchronization HARQ timing relationship corresponding to the UL-Grant, by using location of a downlink subframe located by the UL-Grant, and/or, states of some bits in the UL-Grant.

230, under the circumstances that the UE detects the PHICH from the PHICH location corresponding to the PUSCH at subframe n, which is determined by Tc. or, under the circumstances that the UE detects the UL-Grant from the PHICH location corresponding to the PUSCH at subframe n, which is determined by Tc, when the PUSCH synchronization HARQ timing relationship indicated by the UL-Grant is the same as Tc, behavior of the UE is the same as requirements of existing LTE/LTE-A.

When the UE detects the UL-Grant at subframe (n+k), and the PUSCH synchronization HARQ timing relationship indicated by the UL-Grant is different from Tc, the UE processes retransmission of an uplink HARQ process about subframe n, or processes transmission of a new uplink HARQ process, at a corresponding uplink subframe, according to contents in the UL-Grant and the new PUSCH synchronization HARQ timing relationship. The UE adjusts current PUSCH synchronization HARQ timing relationship to a PUSCH synchronization HARQ timing relationship indicated by the UL-Grant.

Detailed descriptions about the second embodiment of the present invention are provided in the following, accompanying with FIG.5 and FIG.6, which are about two specific embodiments.

A first example

As shown in FIG.7, in the first example, a first system frame employs TDD UL-DL configuration 0, and a second system frame employs TDD UL-DL configuration 3.

Based on 210, after a UE sending PUSCH at subframe 4 of the first system frame, the UE may detect the PHICH at subframe 0 of the second system frame, according to the PUSCH synchronization HARQ timing relationship of current TDD UL-DL configuration 0. The UE may also detect the UL-Grant at subframe 0 of the second system fame, according to Tables 5, 6, or 7.

Since the eNB needs to modify the TDD UL-DL configuration of the second system frame to TDD UL-DL configuration 3, based on the PUSCH synchronization HARQ timing relationship shown in Table 2, the UL-Grant which schedules subframe 4 should be sent at subframe 0, with TDD UL-DL configuration 3. Thus, the eNB needs to send the UL-Grant, which schedules subframe 4 of the second system frame, at subframe 0 of the second system frame, and inform the UE about the new PUSCH synchronization HARQ timing relationship.

Based on 230, after detecting the UL-Grant at subframe 0, the UE may process retransmission of an uplink HARQ process about subframe 4 of the first system frame, or process transmission of a new uplink HARQ process, at subframe 4 of the second system frame, according to contents in the UL-Grant. The UE may also modify current PUSCH synchronization HARQ process to the PUSCH synchronization HARQ process corresponding to TDD UL-DL configuration 3.

A second example

As shown in FIG.8, in the second example, a first system frame employs TDD UL-DL configuration 1, and a second system frame employs TDD UL-DL configuration 0.

Based on 210, after sending the PUSCH at subframe 8 of the first system frame, the UE may detect the PHICH at subframe 4 of the second system frame, according to the PUSCH synchronization HARQ timing relationship of current TDD UL-DL configuration 1. The UE may also detect the UL-Grant at

subframes

4 and 5 of the second system frame, based on Tables 5, 6, or 7.

Since the eNB needs to modify the TDD UL-DL configuration of the second system frame to TDD UL-DL configuration 0, based on the PUSCH synchronization HARQ timing relationship shown in Table 2, the UL-Grant which schedules subframe 9 should be sent at subframe 5, with TDD UL-DL configuration 0. Thus, the eNB needs to send the UL-Grant at subframe 5 of the second system frame, in which the UL-Grant schedules subframe 9 of the second system frame. The eNB may also inform the UE about the new PUSCH synchronization HARQ timing relationship.

Based on 230, after detecting the UL-Grant at subframe 5, the UE should process retransmission of an uplink HARQ process about subframe 8 of the first system frame, or process transmission of a new uplink HARQ process, at subframe 9 of the second system frame, based on contents in the UL-Grant. The UE should also modify current PUSCH synchronization HARQ process to a PUSCH synchronization HARQ process corresponding to TDD UL-DL configuration 0.

Fig. 9 is a schematic diagram illustrating a UE, in accordance with an embodiment of the present invention.

Referring to FIG. 9, a UE comprise a control unit and a communication unit. The control unit may determine location of a next scheduling command corresponding to the uplink HARQ process of the PUSCH, after sending a Physical Uplink Shared Channel (PUSCH). And then, the controller unit may detect an uplink scheduling command at the determined location, and process retransmission of the uplink HARQ process or transmission of a new uplink HARQ process at a corresponding uplink subframe, according to the received uplink scheduling command. The communication unit may retransmit the uplink HARQ process or transmit a new uplink HARQ, according to control of the controller unit.

Persons having ordinary skill in the art may understand and implement foregoing embodiments. All of or part of blocks in the method may be implemented with relevant hardware instructed by a program. The program may be stored in a computer readable storage medium. When executing the program, one block or the combination thereof in forgoing method embodiment may be included.

Besides, each functional unit in each embodiment of the present invention may be integrated into a processing module, or may exist separately. Still alternatively, at least two functional units may be integrated into a module. The foregoing integrated module may be implemented with hardware, or with software functional module. When the integrated module is implemented with software functional module, and is sold or used as an independent product, the integrated module may be stored in a computer readable storage medium.

The storage medium mentioned above may be a Read-Only Memory (ROM), disk or CD-ROM, etc.

The foregoing is only preferred embodiments of the present invention, which are not used for limiting the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention, should be covered by the protection scope of the present invention.

Claims

A method for maintaining transmission continuity of an uplink Hybrid Automatic Repeat Request (HARQ) process in a Time Division Duplexing (TDD) system, comprising:

A, after sending a Physical Uplink Shared Channel (PUSCH), determining, by a User Equipment (UE), location of a next scheduling command corresponding to the uplink HARQ process of the PUSCH;

B, detecting, by the UE, an uplink scheduling command at the determined location;

C, processing, by the UE, retransmission of the uplink HARQ process or transmission of a new uplink HARQ process at a corresponding uplink subframe, according to the received uplink scheduling command.
The method according to claim 1, wherein determining by the UE the location of the next scheduling command corresponding to the uplink HARQ process of the PUSCH in A comprises:

determining, by the UE, location of the uplink subframe located by a next transmission, which corresponds to the uplink HARQ process of the PUSCH, according to current PUSCH synchronization HARQ timing relationship;

taking, by the UE, all of the possible locations where the uplink scheduling command of the uplink subframe appears, as the location of the next scheduling command, under the circumstances of all of the PUSCH synchronization HARQ timing relationships and based on the location of the uplink subframe.
The method according to claim 2, wherein the uplink scheduling command comprises a Physical Hybrid-Automatic Repeat Request (HARQ) Indicator Channel (PHICH), and/or, an uplink Grant (UL-Grant); and B comprises:

for the PHICH, detecting the PHICH at a PHICH location corresponding to the PUSCH, according to current PUSCH synchronization HARQ timing relationship;

for the UL-Grant, detecting the UL-Grant at subframe
based on Table 4;

[Table 4]

wherein, NUlNext is a subframe number of the uplink subframe located by the next transmission.
The method according to claim 3, further comprising:

when the UE detects the UL-Grant at subframe
, and determines that the PUSCH synchronization HARQ timing relationship changes according to the UL-Grant, adjusting, by the UE, current PUSCH synchronization HARQ timing relationship to a PUSCH synchronization HARQ timing relationship corresponding to the UL-Grant.
The method according to claim 1, wherein determining by the UE the location of the next scheduling command corresponding to the uplink HARQ process of the PUSCH in A comprises:

taking, by the UE, all of the possible locations where the uplink scheduling command corresponding to the PUSCH appears, as the location of the next scheduling command, under the circumstances of all of the PUSCH synchronization HARQ timing relationships and based on the location of the PUSCH.
The method according to claim 5, wherein the uplink scheduling command comprises a Physical Hybrid-Automatic Repeat Request (HARQ) Indicator Channel (PHICH), and/or, an uplink Grant (UL-Grant); and B comprises:

for the PHICH, detecting the PHICH at a PHICH location corresponding to the PUSCH, according to current PUSCH synchronization HARQ timing relationship;

for the UL-Grant, detecting the UL-Grant at subframe n+k based on Table 5;

[Table 5]

wherein n is a subframe number located by the PUSCH.
The method according to claim 5, wherein the uplink scheduling command comprises a Physical Hybrid-Automatic Repeat Request (HARQ) Indicator Channel (PHICH), and/or, an uplink Grant (UL-Grant); and B comprises:

for the PHICH, detecting the PHICH at a PHICH location corresponding to the PUSCH, according to current PUSCH synchronization HARQ timing relationship;

for the UL-Grant, detecting the UL-Grant at subframe n+k based on Table 6;

[Table 6]

wherein n is a subframe number located by the PUSCH.
The method according to claim 5, wherein the uplink scheduling command comprises a Physical Hybrid-Automatic Repeat Request (HARQ) Indicator Channel (PHICH), and/or, an uplink Grant (UL-Grant); and B comprises:

for the PHICH, detecting the PHICH at a PHICH location corresponding to the PUSCH, according to current PUSCH synchronization HARQ timing relationship;

for the UL-Grant, detecting the UL-Grant at subframe n+k based on Table 7;

[Table 7]
The method according to any of claims 6 to 8, further comprising:

when the UE detects the UL-Grant at subframe n+k, and determines that the PUSCH synchronization HARQ timing relationship changes based on the UL-Grant, adjusting, by the UE, current PUSCH synchronization HARQ timing relationship to a PUSCH synchronization HARQ timing relationship corresponding to the UL-Grant.
An apparatus implemented by using any one of claim 1 to claim 9.