CN101425880A

CN101425880A - Method and apparatus for answering information cross sub-frame duplicate transmission

Info

Publication number: CN101425880A
Application number: CNA2007101682366A
Authority: CN
Inventors: 陈小波
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2007-10-30
Filing date: 2007-10-30
Publication date: 2009-05-06

Abstract

The invention discloses a retransmission method for ACK/NACK spanning sub-frames, which comprises: configuring a channel set of an uplink prearranged ACK; configuring a primary transmission ACK channel from the ACK channel set for dispatched user devices in a downlink sub-frame according to the implicit mapping mode of the ACK channel; and configuring a repeated ACK channel of repeated feedback ACK/NACK for the spanning sub-frames from the ACK channel set according to the times and the primary transmission ACK channel of the repeated feedback ACK/NACK for the spanning sub-frames required by the user devices. By adopting the invention, the utilization rate of the ACK channel sources can be effectively improved. Corresponding to the method, the invention also provides a retransmission device for the ACK/NACK spanning sub-frames.

Description

Method and device for transmitting response information repeatedly across subframes

Technical Field

The present invention relates to the field of wireless communication technologies, and in particular, to the third generation partnership project (3)^rdA method and apparatus for repeatedly transmitting Acknowledgement/Negative-Acknowledgement (ACK/NACK) across subframes in a general evolution (3 GPP) Evolved universal Radio Access (E-UTRA) system.

Background

In the 3GPP E-UTRA system, a Hybrid automatic-repeat request (HARQ) mechanism is adopted to obtain a higher data transmission rate. The basic process of HARQ is: the receiving end checks whether the received data packet is received correctly, if the data packet is received correctly, the receiving end feeds back the ACK information of successful response to the sending end, and the sending end continues to send the next data packet after receiving the ACK information; if the receiving is incorrect, failure response NACK information is fed back to the sending end, and the sending end retransmits the data packet after receiving the NACK information until ACK is received or the maximum sending times is reached.

In a 3GPP E-UTRA system, ACK/NACK fed back by a User Equipment (UE) to a base station (nodeb) is fed back on a Physical Uplink Control Channel (PUCCH), and there is a fixed time delay between the ACK/NACK fed back by the User Equipment and the time when the base station sends a corresponding downlink data packet to the User Equipment. In one downlink subframe, the base station may schedule downlink data packets of multiple user equipments at the same time, thereby causing a situation that the multiple user equipments simultaneously feed back ACK/NACK, and therefore, an ACK channel for feeding back ACK/NACK needs to be allocated between the base station and the user equipments in some way for each user equipment.

The ACK channel allocation method includes explicit allocation and implicit allocation. Explicit allocation means that the base station signals an ACK channel of the user equipment. For implicit allocation, there are two types, one is to implicitly map the ACK Channel by using a time-frequency resource block allocated by the base station for a Downlink data packet of the user equipment, and the other is to implicitly map the ACK Channel by using a Physical Downlink Control Channel (PDCCH) of a data packet of the user equipment scheduled by the base station. The current 3GPP uplink ACK channel allocation scheme for E-UTRA is as follows: for non-persistent scheduling (which mainly surrounds this scheduling manner), the ACK channel resource for which the user equipment feeds back ACK/NACK is implicitly mapped with the PDCCH issued by the base station in this scheduling, i.e. the second manner of implicit allocation. More specifically, when the problem of repeated feedback ACK/NACK across subframes is not considered, the problem implicitly corresponds to a Control Channel Element (CCE) with the smallest number occupied by a PDCCH.

In a 3GPP E-UTRA system, in order to improve a cell coverage radius, that is, improve a scheduling success rate of edge user equipment, a scheme of repeatedly transmitting ACK/NACK information across subframes is provided, where the repeatedly transmitting ACK/NACK across subframes refers to repeatedly feeding back the same ACK/NACK in multiple uplink subframes. In the 3 gpp-UTRA system, the channel quality of the cell edge ue is poor, and therefore, the ACK/NACK transmission performance needs to be improved by repeatedly feeding back ACK/NACK information across subframes of an uplink.

In the prior art, a scheme for ACK/NACK cross-subframe repeat transmission is provided: for the non-persistently scheduled user equipment, the ACK channel resource of the ACK/NACK information fed back by the user equipment is implicitly mapped through the PDCCH of the base station and the number of the subframe where the corresponding uplink and downlink transmission is located; for the user equipment which is continuously scheduled, the ACK channel resource of the ACK/NACK information fed back by the user equipment is implicitly mapped by the time slot resource occupied by the downlink data packet of the base station and the number of the subframe where the corresponding uplink and downlink transmission is positioned; and the system reserves a corresponding number of ACK channels for each scheduled user equipment in the subframe after determining the times of ACK/NACK repeated transmission according to the condition of the scheduled user equipment in the subframe.

Referring to fig. 1, for a specific example of the above scheme, for a scheduled user equipment in

downlink subframe

0, 3 uplink subframes are reserved for the scheduled user equipment to repeatedly transmit ACK/NACK. For example, after receiving the PDCCH of the base station, the scheduled ue in the downlink subframe 0 automatically maps an ACK channel in the ACK channel resource set labeled 0 in the

corresponding uplink subframes

0, 1, and 2 to feed back ACK/NACK information, so that the feedback ACK/NACK can be repeatedly transmitted at most twice in the scheduled ue in the downlink subframe 0. Similarly, after receiving the PDCCH of the base station, the scheduled user equipment in the downlink subframe 1 automatically maps an ACK channel in the ACK channel resource set labeled 1 of the

corresponding uplink subframes

1 and 2 to feed back ACK/NACK information, so that the fed back ACK/NACK can be repeatedly transmitted at most once in the scheduled user equipment in the downlink subframe 1; after receiving the PDCCH of the base station, the scheduled user equipment in the downlink subframe 2 automatically maps an ACK channel in the ACK channel resource set labeled as 2 of the corresponding uplink subframe 2 to feed back ACK/NACK information, so that the ACK/NACK fed back by the scheduled user equipment in the downlink subframe 2 is not transmitted repeatedly.

The inventor finds that the scheme can realize the repeated transmission of the ACK/NACK across the subframes, but occupies a large amount of ACK resources, and causes great ACK resource waste when less user equipment needing the repeated across the subframes, thereby reducing the uplink spectrum efficiency of the E-UTRA system.

In addition, the way of reserving the ACK channel is not flexible enough, and in some cases, a large delay may be introduced to data transmission of the user equipment that needs to repeatedly feed back ACK/NACK across subframes. Taking fig. 1 as an example, suppose that a certain ue needs to repeat ACK/NACK feedback 2 times, if the ue misses scheduling on the current downlink subframe 0 when a certain data packet is formed, scheduling may be performed on the downlink subframe 1 at the earliest time, but since the scheduled ues on the downlink subframes 1 to 7 do not support repeating ACK/NACK feedback 2 times, it is necessary to repeat ACK/NACK feedback 2 times on the corresponding uplink subframe after the next downlink subframe 0 is scheduled, which introduces an extra delay of 7 subframes for scheduling.

Disclosure of Invention

In view of this, the present invention provides a method and an apparatus for ACK/NACK cross-subframe repeat transmission, so as to solve the problem of channel resource waste caused by reserving ACK channel resources for cross-subframe repeat ACK/NACK in the existing scheme.

Therefore, the embodiment of the invention adopts the following technical scheme:

a method of ACK/NACK cross-subframe repeat transmission, comprising: configuring a reserved ACK channel set; according to an implicit mapping method of an ACK channel, configuring an initial transmission ACK channel from the reserved ACK channel set for the scheduled user equipment in the downlink subframe; and configuring a repeated ACK channel for repeatedly feeding back the ACK/NACK in the cross-subframe from the reserved ACK channel set according to the times of repeatedly feeding back the ACK/NACK in the cross-subframe and the initial transmission ACK channel required by the user equipment.

An apparatus for ACK/NACK cross-subframe repeat transmission, the apparatus being located on a network side, comprising: a primary configuration unit, configured to configure a primary ACK channel for user equipment from a reserved ACK channel set according to an ACK channel implicit mapping manner, and an ACK/NACK receiving unit, configured to receive ACK/NACK feedback information from the configured ACK channel, further including: a repetition frequency configuration unit, configured to configure the frequency of ACK/NACK feedback required by the ue through physical layer signaling or high layer signaling; and the repeated configuration unit is used for configuring a repeated ACK channel used by the user equipment for repeatedly feeding back the ACK/NACK in a cross-subframe manner from the reserved ACK channel set according to the initial transmission ACK channel and the times of repeatedly feeding back the ACK/NACK in a cross-subframe manner.

An apparatus for ACK/NACK cross-subframe repeat transmission, the apparatus being located at a user side, comprising: the device comprises a repeated frequency analysis unit, a feedback unit and a feedback unit, wherein the repeated frequency analysis unit is used for receiving a physical layer signaling or a high layer signaling so as to acquire the frequency of repeatedly feeding back ACK/NACK across subframes; the channel analysis unit is used for analyzing the initial ACK channel from the reserved ACK channel set according to an ACK channel implicit mapping method; analyzing a repeated ACK channel from a reserved ACK channel set by using the number of times of repeatedly feeding back ACK/NACK by the initial ACK channel and the cross subframe; and the feedback response unit is used for normally feeding back ACK/NACK on the initial ACK channel and repeatedly feeding back ACK/NACK on the repeated ACK channel in each corresponding subframe according to the analysis result of the channel analysis unit.

Therefore, the scheme utilizes the vacant ACK channel in the reserved ACK channel set caused by the implicit mapping method of the ACK channel of the system to transmit the cross-subframe repeated ACK/NACK information starting from the previous subframe, and avoids reserving special ACK channel resources for the cross-subframe repeated ACK/NACK, so that the utilization rate of the reserved ACK channel resources is improved, and the uplink spectrum efficiency is improved.

Drawings

FIG. 1 is a diagram illustrating cross-subframe retransmission of ACK/NACK in the prior art;

FIG. 2 is a flow chart of a first embodiment of the method of the present invention;

FIG. 3 is a schematic diagram illustrating an embodiment of a method according to the present invention;

FIG. 4 is a flowchart illustrating a method according to an embodiment of the present invention;

FIG. 5 is a second schematic diagram of an example of a first embodiment of the method of the present invention;

FIG. 6 is a diagram of a second embodiment of the method of the present invention;

FIG. 7 is a third exemplary illustration of a method according to an embodiment of the present invention;

FIG. 8 is a flowchart of a second embodiment of the method of the present invention.

Detailed Description

In summary, embodiments of the present invention provide a method comprising the steps of:

step 001: configuring a reserved ACK channel set;

the reserved ACK channel set is reserved by the system for implicit mapping of initial ACK channels of all scheduled user equipment in uplink subframes according to the implicit mapping method of the used ACK channels.

Step 002: according to an implicit mapping method of an ACK channel, configuring an initial transmission ACK channel from the reserved ACK channel set for the scheduled user equipment in the downlink subframe;

step 003: and configuring a repeated ACK channel for repeatedly feeding back the ACK/NACK in the cross-subframe from the reserved ACK channel set according to the times of repeatedly feeding back the ACK/NACK in the cross-subframe and the initial transmission ACK channel required by the user equipment.

In the embodiment of the invention, for non-persistent scheduling, an initial transmission ACK channel used by the user equipment for feeding back ACK/NACK for the first time and a repeated ACK channel used by the cross-subframe repeated feedback ACK/NACK are implicitly mapped by an ACK channel implicit mapping method; the number of times the feedback is repeated for the ACK across subframes may be explicitly signaled by the physical layer signaling of the base station, preferably by higher layer signaling above the physical layer.

The implicit mapping method of the ACK channel includes a plurality of methods, which can be referred to in patent application No. 200710076820.9 filed on 31/8/2007 by huashi technology limited, in the name of the present applicant.

One method for implicit mapping of the ACK channel is implicit mapping of CCEs to the ACK channel. In the 3gpp e-UTRA system, the non-persistently scheduled ACK/NACK channel is implicitly mapped by the PDCCH transmitted by the base station. Wherein, the PDCCH may consist of 1, 2, 4 or 8 CCEs according to the channel quality status of the user equipment, and thus the ACK channel is implicitly mapped through the CCEs occupied by the PDCCH. More specifically, an ACK channel used by the ue for feeding back the initial ACK/NACK of the primary scheduling packet implicitly corresponds to the CCE with the smallest label occupied by the PDCCH. For user equipment that needs to repeatedly feed back ACK/NACK information across subframes, its channel quality is poor, so that the PDCCH is usually composed of multiple CCEs, for example, 8 or 4 CCEs. When the ACK channel is implicitly mapped through the CCE, a PDCCH consisting of 4 or 8 CCEs is usually mapped to multiple ACK channels at the same time, for example, when one CCE corresponds to one ACK channel, a PDCCH occupying 8 CCEs is mapped to 8 ACK channels at the same time, however, at one time, only one ACK channel is used by one ue to feed back ACK/NAK, and the remaining ACK channels are not utilized, thereby causing waste.

Another implicit mapping method for the ACK channel is implicit mapping of time-frequency resources and the ACK channel. For the way of implicitly mapping the ACK channel by the time-frequency resources occupied by the user equipment during scheduling, the user equipment occupying more time-frequency resources may also be allocated with a plurality of ACK channels at the same time, thereby causing waste. In the 3GPP E-UTRA system, time-frequency resources for scheduling user equipment data are allocated in units of Resource Blocks (RBs), and the size of an RB is 12 consecutive subcarriers in the frequency domain and 1 millisecond in time. For example, when one RB corresponds to one ACK channel, a user equipment occupying a plurality of RBs during scheduling is simultaneously allocated with a plurality of ACK channels, but one user equipment only uses one ACK channel to feed back ACK/NACK at one time, which is wasteful.

The embodiment of the invention is not limited to the two implicit mapping methods of the ACK channel. That is, the embodiments of the present invention are applicable to any ACK channel mapping scheme that may implicitly map a plurality of ACK channels for one user equipment at the same time.

In the first embodiment, the mapping from CCE to ACK channel will be described as an example. Subsequently, in the second embodiment, a scheme for implementing the method for mapping the time-frequency resources to the ACK channels will be described.

The mapping of the CCE to the ACK channel is specifically: for non-persistent scheduling, the ACK channel is implicitly mapped through a PDCCH issued by the base station, and specifically, the ACK channel used for the initial ACK/NACK feedback of the user equipment implicitly corresponds to a CCE with the smallest label occupied by the PDCCH.

For a communication system, a method of an embodiment of the invention comprises the following steps:

step 101: the system configures a reserved ACK channel set;

the reserved ACK channel set is reserved by the system for implicit mapping of initial ACK channels of all scheduled user equipment in uplink subframes according to the used implicit mapping method of the ACK channels.

Step 102: the system configures the times of cross-subframe repeated feedback ACK/NACK for the user equipment which needs to repeatedly feed back the ACK/NACK information;

wherein the configuring of the number of times of repeatedly feeding back the ACK/NACK across the subframes may be accomplished by notifying the user equipment through physical layer signaling or higher layer signaling.

Step 103: the user equipment receives the PDCCH, and selects an ACK channel implicitly corresponding to the CCE with the minimum label number occupied by the PDCCH as an initial transmission ACK channel;

step 104: and configuring a repeated ACK channel for repeatedly feeding back the ACK/NACK across the subframes according to the times of repeatedly feeding back the ACK/NACK across the subframes required by the user equipment and the used initial transmission ACK channel. Wherein the duplicate ACK channel belongs to the set of reserved ACK channels.

In the above configuration process, in a preferred embodiment, a duplicate ACK channel may be first selected from the ACK channels corresponding to the PDCCH, and if an idle ACK channel cannot be selected in the set, the duplicate ACK channel is selected from the remaining channels other than the ACK channel corresponding to the PDCCH.

In the above configuration process, the number of repeated ACK channels may be the same as the number of repeated feedback ACK/NACK times, or the number of repeated ACK channels may be smaller than the number of repeated feedback ACK/NACK times. The latter is more beneficial to improving the utilization rate of channel resources, but in this case, it is to be ensured that the repeated ACK channel for transmitting ACK/NACK for many times is not occupied by other user equipments.

In the above configuration process, a preferred method for determining the number of repeated ACK channels is: the relation between the number n of ACK channels capable of implicitly mapping the ACK channels by the PDCCH and the number m of repeated feedback across subframes is as follows: n is more than or equal to m + 1. And configuring the ACK channels for repeating ACK/NACK feedback for m times across subframes in the remaining n-1 ACK channels except the initial transmission ACK channel. The implementation method has the advantages that the influence of the repeated ACK channel on the mapping from the PDCCH of the subsequent subframe to the CCE can be reduced, because each user equipment can only obtain the CCE occupied by the PDCCH at the scheduled time, and the scheduling information of other user equipment cannot be obtained.

Step 105: and the user equipment feeds back the initially transmitted ACK/NACK on the initially transmitted ACK channel and feeds back the retransmitted ACK/NACK on the repeated ACK channel in each uplink subframe corresponding to the PDCCH or the corresponding downlink data packet.

Referring to fig. 2, a flowchart of the first embodiment is a method at a ue side:

step 200: each user equipment receives a reserved ACK channel set configured by the system;

step 201: the user equipment receives the physical layer signaling or the high layer signaling and learns the times of repeatedly feeding back ACK/NACK;

step 202: and the user equipment receives the PDCCH issued when the base station schedules, thereby acquiring an initial ACK channel and a repeated ACK channel.

Specifically, the user equipment receives a PDCCH issued when the base station schedules a data packet, and acquires an ACK channel used by initial transmission ACK/NACK through implicit mapping between the PDCCH (namely CCE) adopted by the system and the ACK channel; and meanwhile, the user equipment acquires the repeated ACK channel according to the configuration rule of the system about the initial ACK channel. The configuration rule of the repeated ACK channel refers to step 102.

Step 203: the user equipment receives a data packet which is issued by a base station and corresponds to the PDCCH, and determines whether to feed back ACK or NACK according to whether the data packet is successfully received or not;

step 204: and the user equipment respectively uses the ACK channels configured in the step 102 in the corresponding uplink subframes to successively feed back the ACK/NACK scheduled this time.

In the 3GPP E-UTRA system, the channel quality of the cell edge ue is poor, so that ACK/NACK needs to be repeatedly fed back across subframes in the uplink to improve the ACK/NACK transmission performance, and because the channel quality of the cell edge is poor, the PDCCH transmitted by the base station usually consists of multiple CCEs, for example, 8 CCEs or 4 CCEs. In the mapping process of CCE to ACK channel, PDCCH consisting of multiple CCEs is mapped to multiple ACK channels. When the user equipment reports the ACK/NACK, one user equipment can only use one ACK channel at one moment, and the rest ACK channels can configure the rest user equipment to transmit the ACK/NACK which is fed back repeatedly by crossing the subframe starting from the previous subframe, so that the utilization rate of the ACK channel is improved.

In step 102 and step 202, the implicit mapping from the PDCCH to the ACK channel is implicit mapping from the CCE occupied by the PDCCH to the ACK channel, and in a preferred embodiment, the initial ACK/NACK is fed back by the ACK channel implicitly corresponding to the CCE with the smallest label occupied by the PDCCH. The method provided by the embodiment of the invention is described in detail by combining the specific examples.

The first embodiment is as follows:

for the mapping relationship between the PDCCH and the ACK channel, the simplest is a mapping mode that one CCE maps one ACK channel, and when the user equipment reports ACK/NACK, the normal ACK/NACK is fed back by using the ACK channel corresponding to the CCE with the minimum label occupied by the received PDCCH. For the scheme that CCEs correspond to ACK channels one by one, the number of the reserved ACK channels is equal to or larger than the number of the CCEs, so that each CCE is ensured to have the corresponding ACK channel.

Referring to fig. 3, for a simple example of a CCE to ACK channel one-to-one mapping scheme, there are 16 CCEs 0 to 15, and 16 ACK channels ACK0 to ACK15 are reserved, and they correspond to each other. At a certain downlink time, the base station schedules five user equipments, namely user equipment 0 to user equipment 4, wherein the PDCCH of each user equipment respectively occupies CCEs 0 to 7, 8 to 11, 12 to 13, 14 and 15.

Referring to fig. 4, a flowchart of a first embodiment includes the following steps:

step 400: each user equipment receives a reserved ACK channel set configured by the system;

step 401: each user equipment receives a physical layer signaling or a high layer signaling and learns the times of repeatedly feeding back ACK/NACK (acknowledgement/negative acknowledgement) required by the user equipment;

specifically, it is assumed that the times for which the user equipment 0 to 4 need to repeatedly feed back ACK/NACK are 3, 1, 0, and 0, respectively.

When the number of times of feedback repetition is required to be 0, the default is that the ACK/NACK feedback does not need to be repeated, step 401 may not be executed, and an ACK channel for repeated feedback does not need to be configured.

Step 402: at a certain downlink time, each scheduled user equipment receives a PDCCH;

step 403: each user equipment analyzes the PDCCH and acquires an initial ACK channel for normally feeding back ACK/NACK according to an implicit mapping method from the PDCCH to the ACK channel;

specifically, the ACK channels mapped by the user equipments 0 to 4 are ACK0 to ACK7, ACK8 to ACK11, ACK12 to ACK13, ACK14, and ACK15, respectively, and ACK/NACK is fed back normally on the ACK channels ACK0, ACK8, ACK12, ACK14, and ACK15, respectively. Thus, at this time, ACK 1-ACK 7, ACK 9-ACK 11, and ACK13 would be blanked and used to transmit a cross-subframe repeat ACK/NACK starting in the previous subframe. Similarly, for the repeated ACK/NACK of the cross-subframe of each user equipment of the current subframe, the feedback can be carried out by the idle ACK channel of each subsequent subframe.

It should be noted that, the first ACK channel is preferably used as the initial ACK channel for better compatibility with the prior art and to facilitate selection of the subsequent repeated ACK channel, but the embodiment of the present invention is not limited to this specific selection manner.

Step 404: each user equipment configures a repeated ACK channel for repeatedly feeding back ACK/NACK by using an initial transmission ACK channel and the repeated feedback times of the cross subframe, wherein the repeated ACK channel belongs to the reserved ACK channel set;

step 405: each user equipment determines whether to feed back ACK or NACK according to the receiving condition of the data packet;

step 406: and the user equipment respectively uses the ACK channels configured in the step 102 in the corresponding uplink subframes to successively feed back the ACK/NACK scheduled this time.

Preferably, the ACK channel mapped by the CCE corresponding to the PDCCH of the scheduled user equipment is selected as the duplicate ACK channel.

Preferably, in the process of configuring the ACK/NACK channel for repeatedly feeding back the ACK/NACK, the ACK channel may be selected as the ACK/NACK channel for repeatedly feeding back the ACK/NACK according to a certain priority. One preferred priority setting is: the first priority comprises ACK channels corresponding to CCEs with odd labels; the second priority contains the ACK channels corresponding to CCEs whose index is a multiple of 2 but not a multiple of 4; the third priority level contains the ACK channels corresponding to CCEs with the index being a multiple of 4 but not a multiple of 8; the fourth priority contains ACK channels corresponding to CCEs numbered as multiples of 8.

Taking the user equipment 0 in fig. 3 as an example, it is preferable to select from the ACKs 0 to the ACK 7. More preferably, the ACK channel corresponding to the odd numbered CCE among the ACKs 0 to 7 is preferentially selected.

The reason why the above-described method of configuring the duplicate ACK/NACK channel can be well combined with the ACK/NACK channel mapping method without collision is that in the mapping from PDCCH to CCE based on the tree structure, CCEs occupied by PDCCH consisting of k1, 2, 4, and 8 CCEs are consecutive k CCEs starting from a CCE with an integral multiple of k, and CCEs are generally occupied sequentially from large to small according to the number of CCEs occupied by PDCCH, for example, the number of CCEs occupied by user equipment 0 to user equipment 4 receiving PDCCH is sequentially reduced in fig. 4. Then, the ACKs 1, the ACKs 3, the ACKs 5 and the ACKs 7 can be implicitly mapped to the initial ACK channel of other user equipments in the subsequent subframe only after the corresponding CCE is occupied by the PDCCH consisting of 1 CCE, and after being configured as the repeated ACK channel, the impact on PDCCH-to-CCE mapping when scheduling other user equipments in the subsequent subframe is minimal.

For example, the user equipment 0 preferably uses ACK1, ACK3, and ACK5 of the subsequent subframes when repeating feedback ACK/NACK three times across subframes next. Referring to fig. 5, it is a schematic diagram of the user equipment 0 repeatedly feeding back ACK/NACK across subframes. The first uplink subframe normally feeds back ACK/NACK by using ACK0, the second uplink subframe repeatedly feeds back ACK/NACK for the first time by using ACK1, the third uplink subframe repeatedly feeds back ACK/NACK for the second time by using ACK3, and the fourth uplink subframe repeatedly feeds back ACK/NACK for the third time by using ACK 5. The first uplink subframe to the fourth uplink subframe may be continuous or discontinuous, and preferably, each subframe is continuous, so that the time delay of ACK/NACK feedback can be effectively reduced.

In addition, it should be noted that when the user equipment 0 uses each ACK channel as the cross-subframe repeated feedback ACK/NACK, the CCE corresponding to the ACK channel cannot be allocated by the base station as the CCE with the smallest label of other PDCCHs, so as to avoid collision.

In the example of fig. 5, the duplicate ACK channel is configured in the ACK channel corresponding to the CCE configuring the PDCCH of user equipment 0, that is, the duplicate ACK channel is selected from ACK0 to ACK7, and actually, as described above, the duplicate ACK channel of user equipment 0 may be selected from ACK channels corresponding to other user equipments in the downlink subframe, that is, within the range of ACK0 to ACK15, as long as it is ensured that when a certain CCE corresponding to the ACK channel is repeated as the duplicate ACK channel, the CCE corresponding to the ACK channel is not allocated to other PDCCHs, so as to avoid collision.

Example two:

although the scheme for one-to-one mapping of CCEs to ACK channels in the first example is simple, considering that one PDCCH usually occupies multiple CCEs, a large reserved ACK channel set is introduced, and a certain waste is also caused, therefore, the mapping scheme of the number of CCEs redundant in number of ACK channels is adopted in the present example.

In this embodiment, the other steps are the same as those in the first embodiment, except that the repeated ACK channel is configured differently depending on the mapping method between the PDCCH (or CCE) and the ACK channel.

Preferably, the unused ACK channel left unused under the mapping method is configured as a duplicate ACK channel.

The mapping method of PDCCH (or CCE) and ACK channel is specifically that PDCCH may be divided into two groups according to the number of occupied CCEs, where the first group is PDCCH composed of 2, 4 and 8 CCEs, and mapping is started from the CCE with the smallest label, and this group is labeled PG 1; the second group is PDCCHs consisting of 1 CCE, which is mapped in reverse order starting from the largest-numbered CCE, and this group is labeled PG 2. Each two CCEs in PG1 correspond to one ACK channel, and each CCE in PG2 corresponds to one ACK channel.

See fig. 6. Assuming that 8 ACK channels are reserved for 16 CCEs, the normal ACK/NACK mapped by the PDCCH in PG1 is fed back on the ACK channel corresponding to the smallest number CCE occupied by the normal ACK/NACK, and the normal ACK/NACK mapped by the PDCCH in PG2 is fed back on the ACK channel corresponding to the CCE occupied by the normal ACK/NACK.

Assume that at some point, the base station schedules four user equipments: user equipment 0 to user equipment 3, wherein the PDCCHs of the user equipment respectively occupy CCEs 0 to 7, CCEs 8 to 11, CCEs 12 to 13 and CCE 15. At the corresponding uplink time when the ACK/NACK is fed back, each user equipment implicitly maps the ACK channel through the CCE occupied by the PDCCH: the ACK information comprises ACK 0-ACK 3, ACK 4-ACK 5, ACK6 and ACK7, and normal ACK/NACK information is fed back by using ACK0, ACK4, ACK6 and ACK7 respectively. At this point ACK2, ACK3, and ACK5 are left unused.

In a preferred embodiment, ACK2, ACK3, and ACK5 are used to transmit feedback that repeats ACK/NACKs across subframes starting at a previous subframe. In this example, there are fewer idle ACK channels than in the first example, and therefore the channel utilization is higher.

In the example shown in fig. 6, after the base station schedules four ues, there is still a CCE14 unused, and its corresponding ACK6 is also empty, and if a ue 4 consisting of a CCE is placed here, then the ue 4 and the ue 2 are mapped to ACK6 at the same time, resulting in collision.

Example three:

referring to fig. 7, the corresponding relationship between CCEs and ACK channels is further optimized, where the ACK channel corresponding to the CCE where PG2 is configured on each PDCCH is different from the ACK channel corresponding to the first CCE of PG1 on each PDCCH. When the number of the user equipment scheduled at the same time is not more than 8, and the total number of CCEs occupied is not more than 16, the ACK channels between the implicitly mapped user equipment are not collided according to the mapping relation.

For example, at this time, on the basis of the example in fig. 6, one more user equipment 4 is added to occupy CCE14, and then after implicit mapping, user equipment 0 to user equipment 4 respectively use ACK0, ACK4, ACK6, ACK7, and ACK1 to feed back their own ACK/NACK.

Based on the ACK mapping methods of fig. 6 and 7, it is preferable that, in configuring the ACK/NACK channel for repeatedly feeding back the ACK/NACK, the ACK channel may be selected as the ACK/NACK channel for repeatedly feeding back the ACK/NACK according to a certain priority. One preferred priority setting is: the first priority contains the ACK channels corresponding to CCEs numbered as multiples of 2 but not as multiples of 4; the second priority contains the ACK channels corresponding to CCEs numbered as multiples of 4 but not as multiples of 8; the third priority contains ACK channels corresponding to CCEs numbered as multiples of 8.

For example, assuming that for user equipment 0, the base station needs to repeat across subframes for 3 times by configuring ACK/NACK feedback thereof through high-layer signaling, in one-time scheduling, PDCCH of user equipment 0 occupies 8 CCEs 0 to 7, then ACK channels that can be allocated through mapping from CCEs to ACK channels are ACK0 to ACK3, user equipment 0 occupies ACK0 when normally feeding ACK/NACK back to the base station, and the remaining 3 times of repeated ACK/NACK feedback across subframes may sequentially use ACK1, ACK2, and ACK 3.

Preferably, for the cross-subframe repeated ACK/NACK feedback of user equipment 0, the three occupied channel preference orders are ACK1, ACK3, and ACK 2. When the user equipment 1 repeatedly feeds back the ACK/NACK twice across the subframes, the ACK1 and the ACK3 may be sequentially selected.

The preferred embodiment described above can be well combined with the ACK mapping method described above without collision. Since, in PG1, ACK1 and ACK3 can only be mapped to other user equipments by PDCCH occupancy consisting of two CCEs, ACK2 can be mapped to other user equipments by PDCCH occupancy consisting of two CCEs or four CCEs.

It should be noted that, when the user equipment 0 uses ACK1 to feed back the downlink time corresponding to ACK/NACK, the base station cannot use CCE2 as any starting CCE occupied by the scheduled PDCCH in PG1, and cannot use CCE14 as any CCE occupied by the scheduled PDCCH in PG2, so as to avoid collision.

In the example of the first embodiment, if it is required to support that the maximum cross-subframe repetition number of ACK/NACK is configured to be 3 for a user equipment whose PDCCH is composed of 8 CCEs, it is preferable that a PDCCH composed of 8 CCEs is mapped with a minimum of 4 ACK channels in implicit mapping of CCEs to ACK channels, which is beneficial for a plurality of user equipments which repeatedly feed back ACK/NACK across subframes to multiplex the cross-subframe ACK channels.

The advantageous effects of the above examples are specifically described below. Suppose that at time points t0, t0+1, t0+2, and t0+3 of downlink, 4 user equipments are scheduled on CCE0 to CCE 7: the ACK/NACK fed back by each user equipment needs to be repeated 3 times across subframes for user equipment 0 to user equipment 3, and ACK channels used for transmitting the initial ACK/NACK feedback and the repeated ACK/NACK feedback across subframes in the ACK channels implicitly mapped by CCE0 to CCE7 are sequentially: the ACK0 to the ACK3 are respectively shown in table 1, where T is a fixed time delay between the sending of the PDCCH by the base station and the feedback of the ACK/NACK by the ue, and at the corresponding uplink time T0+ T-T0 + T +6 of the ACK/NACK feedback, the ACK channels used by the ues 0 to 3 are shown in table 1.

TABLE 1

As can be seen from table 1, the sliding of the ACK channel used by repeating the ACK/NACK feedback across subframes is just multiplexed with the four user equipments, so that no collision occurs. Moreover, in order to reduce the delay of ACK/NACK feedback, when ACK/NACK is repeatedly fed back across subframes, a plurality of subframes occupied by one ACK/NACK is generally continuous.

Therefore, after the base station implicitly maps a plurality of ACK channels through the PDCCH issued when the user equipment is scheduled or the used time-frequency resources, the empty ACK channels are utilized to transmit the cross-subframe repeated ACK/NACK information starting from the previous subframe, thereby improving the utilization rate of reserved ACK channel resources, avoiding reserving special ACK channel resources for the cross-subframe repeated ACK/NACK and providing uplink spectrum efficiency.

In addition, the implementation mode of the invention does not influence the existing implicit mapping scheme, has good compatibility with the existing scheme and is easy to realize.

The following describes a second embodiment of mapping between time-frequency resources and ACK channels:

referring to fig. 8, an embodiment includes the following steps:

step 800: each user equipment receives a reserved ACK channel set configured by the system;

step 801: the user equipment receives a physical layer signaling or a high layer signaling and acquires the times of repeatedly feeding back ACK/NACK across subframes;

step 802: the user equipment receives a PDCCH (physical downlink control channel) issued during scheduling of a base station and a downlink data packet corresponding to the PDCCH, and acquires an initial ACK channel and a repeated ACK channel configured by a system;

specifically, the user equipment receives a PDCCH issued during base station scheduling, receives a downlink data packet, analyzes time-frequency resources allocated by the base station for the downlink data packet through the PDCCH, or learns the time-frequency resources allocated by the base station for the downlink data packet through the received data packet, and implicitly maps an initial transmission ACK channel through the occupied time-frequency resources; and analyzing and obtaining a repeated ACK channel used by repeated feedback of ACK/NACK of each subsequent uplink subframe according to the initial transmission ACK channel and the times of repeated feedback of ACK/NACK of the cross-subframe, wherein the repeated ACK channel belongs to a reserved ACK channel set.

Step 803: and the user equipment respectively uses the ACK channels configured in the step 802 in the corresponding uplink subframes to successively feed back the ACK/NACK scheduled this time.

Wherein, the ACK channel used by the initial ACK/NACK is preferably implicitly mapped by the first or last RB of the time-frequency resource.

For implementation details of the second embodiment, reference may be made to the first embodiment, which is not described herein again.

Corresponding to the method, the embodiment of the invention also provides a device for ACKACK/NACK repeated transmission across subframes, which exists at the network side and can be a base station or a functional entity in the base station.

Specifically, the device comprises the following parts:

a primary configuration unit, configured to configure a primary ACK channel for the user equipment from the reserved ACK channel set according to the implicit mapping mode of the ACK channel,

an ACK/NACK receiving unit for receiving ACK/NACK feedback information from the configured ACK channel,

in particular, the device further comprises:

a repetition frequency configuration unit, configured to configure the frequency of ACK/NACK feedback required by the ue through physical layer signaling or high layer signaling;

and the repeated configuration unit is used for configuring a repeated ACK channel used by the user equipment for repeatedly feeding back the ACK/NACK in a cross-subframe manner from the reserved ACK channel set according to the initial transmission ACK channel and the times of repeatedly feeding back the ACK/NACK in a cross-subframe manner.

For details of the implementation of the apparatus, reference is made to the method embodiment, which is not described herein again.

In addition, the embodiment of the invention also provides a device for repeatedly transmitting the ACK/NACK across the subframes at the user side, and the device can be user equipment or a functional entity inside the user equipment.

Specifically, the device comprises the following parts:

the device comprises a repeated frequency analysis unit, a feedback unit and a feedback unit, wherein the repeated frequency analysis unit is used for receiving a physical layer signaling or a high layer signaling so as to acquire the frequency of repeatedly feeding back ACK/NACK across subframes;

the channel analysis unit is used for analyzing the initial ACK channel from the reserved ACK channel set according to an ACK channel implicit mapping method; analyzing a repeated ACK channel from a reserved ACK channel set by using the number of times of repeatedly feeding back ACK/NACK by the initial ACK channel and the cross subframe;

and the feedback response unit is used for normally feeding back ACK/NACK on the initial ACK channel and repeatedly feeding back ACK/NACK on the repeated ACK channel in each corresponding subframe according to the analysis result of the channel analysis unit.

Details of the implementation of the above-described apparatus existing at the user side are not described again, and reference may be made to the method embodiment.

In addition, when the ACK/NACK information fed back by the user is repeated across subframes, the embodiment of the present invention further provides a method for coordinating and allocating an ACK channel between the user equipment and the base station: the system reserves special ACK channel resources for the repeated ACK/NACK feedback information of the cross subframe; in a session establishment stage, a base station configures the repetition times of feedback ACK/NACK and an ACK channel occupied by the repeated ACK/NACK across subframes for user equipment through signaling; in order to save the resource amount of the ACK channel reserved for the cross-subframe repeated ACK/NACK feedback information by the system and improve the use efficiency of the reserved ACK channel set, the cross-subframe repeated ACK/NACK information of different user equipment can be multiplexed on the same ACK channel in a subframe-level time division multiple access multiplexing mode. For the users needing to repeatedly feed back the ACK/NACK information across the subframes, the ACK channel occupied by the primary feedback of each piece of ACK/NACK information can be kept the same as the ACK channel distribution mode of the user equipment not needing to repeatedly feed back the ACK/NACK information across the subframes.

In the scheme, the system can allocate the ACK channel to each user equipment according to the ACK resource actually required by the user equipment, and compared with a high-pass scheme, the system can save the ACK resource which needs to be reserved for the cross-subframe repeated ACK/NACK information, and improve the uplink spectrum efficiency of the E-UTRA system.

Specifically, in this scheme, in order to support the user equipment to repeatedly feed back the ACK/NACK information across subframes to improve the coverage radius of the cell, when the system reserves ACK channel resources for the ACK/NACK feedback information, two independent SETs of ACK channel resources SET _ ACK and SET _ ACK _ REP are reserved. For users who do not need to repeatedly feed back ACK/NACK information across subframes, ACK channel resources of the users are positioned in a SET SET _ ACK and are distributed according to explicit or implicit mapping; for the user equipment which needs to repeatedly feed back the ACK/NACK information across the sub-frames, the ACK/NACK information fed back each time is divided into two parts, namely primary ACK/NACK feedback and repeated ACK/NACK feedback across the sub-frames for convenient description. The ACK channel resource for repeating ACK/NACK feedback across the subframes is positioned in a SET SET _ ACK _ REP and is configured by a base station through signaling; the ACK channel resources for the initial ACK/NACK feedback may be located in the SET _ ACK and allocated by an explicit or implicit technique, or may be located in the SET _ ACK _ REP and configured by the base station through signaling. When the base station configures the ACK channel resources for the user equipment from the SET _ ACK _ REP, the signaling used may be physical layer signaling or higher layer signaling from above the physical layer.

In a 3GPP E-UTRA system, for non-persistent scheduling, user equipment implicitly maps ACK channel resources from a SET SET _ ACK through a PDCCH issued by a base station during scheduling; for persistent scheduling, the base station may also have some mechanism to allocate ACK channel resources for users from the SET _ ACK, e.g., explicitly signaled by a higher layer signaling. Considering that the base station always allocates an ACK channel in the SET SET _ ACK for each user equipment, for the user equipment needing to repeatedly feed back ACK/NACK information across subframes, preferably, ACK channel resources fed back by the initial ACK/NACK are allocated from the SET SET _ ACK through implicit mapping, and when a session is established, the ACK channel resources for the user equipment needing to repeatedly feed back ACK/NACK information across subframes are configured with the times of repeating across subframes and the ACK/NACK feedback across subframes through high-layer signaling.

In order to further reduce the number of ACK channels reserved by the system for the SET _ ACK _ REP and improve the utilization rate of the reserved ACK channels in the SET _ ACK _ REP, the base station may configure the same ACK channel for the cross-subframe repeated ACK/NACK feedback of multiple users through signaling. At this time, the plurality of base stations need to multiplex their cross-subframe repetition ACK/NACK feedback onto the same ACK channel in a subframe-level time division multiple access multiplexing manner, and need to avoid collision of their cross-subframe repetition ACK/NACK feedback through scheduling of a base station scheduler.

In the scheme, the base station allocates the ACK resource fed back by the cross-subframe repeated ACK/NACK for the user equipment according to the actual requirement of the user equipment, so that the ACK resource required to be reserved for the cross-subframe repeated ACK/NACK information can be saved, and the uplink spectrum efficiency of the E-UTRA system is improved.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A method for ACK/NACK repeated transmission across subframes, comprising:

configuring a reserved ACK channel set;

according to an implicit mapping method of an ACK channel, configuring an initial transmission ACK channel from the reserved ACK channel set for the scheduled user equipment in the downlink subframe;

and configuring a repeated ACK channel for repeatedly feeding back the ACK/NACK in the cross-subframe from the reserved ACK channel set according to the times of repeatedly feeding back the ACK/NACK in the cross-subframe and the initial transmission ACK channel required by the user equipment.

2. The method of claim 1,

configuring the priority of each ACK channel;

and according to the priority of the ACK channels, selecting the ACK channel with the highest priority as a repeated ACK channel.

3. The method according to claim 2, wherein the implicit mapping method for the ACK channel refers to an implicit mapping method from a Control Channel Element (CCE) included in a Physical Downlink Control Channel (PDCCH) to the ACK channel;

wherein,

when the CCEs correspond to the ACK channels one by one, the ACK channels corresponding to the CCEs with odd labels are configured to have the highest priority;

when some or all of the ACK channels correspond to a plurality of CCEs, respectively, the ACK channel corresponding to a CCE whose configuration index is divisible by 2 but not divisible by 4 has the highest priority.

4. The method of claim 2, wherein the implicit mapping method for the ACK channel refers to an implicit mapping method from resource blocks RB contained in the time-frequency resources to the ACK channel;

wherein,

when the RBs correspond to the ACK channels one by one, configuring the ACK channels corresponding to the RBs with odd numbers with the highest priority;

when part or all of the ACK channels correspond to a plurality of RBs, respectively; CCEs whose configuration index is divisible by 2 but not divisible by 4 correspond to the highest ACK channel priority.

5. The method according to any of claims 1 to 4, wherein the duplicate ACK channel is preferentially selected among ACK channels other than the primary ACK channel.

6. The method according to claim 5, wherein the duplicate ACK channel is preferentially selected within an ACK channel corresponding to the PDCCH or a time-frequency resource.

7. The method of claim 6, wherein the ACK channel corresponding to the CCE with the smallest label is selected as the initial ACK channel.

8. The method of claim 7, wherein the number of times the user equipment needs to repeat the feedback of the ACK/NACK across the subframes is signaled by physical layer signaling or higher layer signaling.

9. An apparatus for ACK/NACK cross-subframe repeat transmission, the apparatus being located on a network side, comprising:

a primary configuration unit, configured to configure a primary transmission ACK channel for the user equipment from the system uplink reserved ACK channel set according to the implicit mapping mode of the ACK channel,

it is characterized by also comprising:

and the repeated configuration unit is used for configuring a repeated ACK channel used by the user equipment for repeatedly feeding back the ACK/NACK in a cross-subframe manner from the system uplink reserved ACK channel set according to the initial transmission ACK channel and the times of repeatedly feeding back the ACK/NACK in a cross-subframe manner.

10. An apparatus for ACK/NACK cross-subframe repeat transmission, the apparatus being located at a user side, comprising:

the channel analysis unit is used for analyzing an initial transmission ACK channel from the system uplink reserved ACK channel set according to an ACK channel implicit mapping method; analyzing a repeated ACK channel from a system uplink reserved ACK channel set by using the times of the initial transmission ACK channel and the times of the repeated feedback ACK/NACK of the cross-subframe;