CN102123016A - Method for determining acknowledgement (ACK)/negative acknowledgement (NACK) channel - Google Patents

Abstract

The invention discloses a method for determining a acknowledgement (ACK)/negative acknowledgement (NACK) channel in a wireless communication system of asymmetric carrier aggregation, the method comprises the following steps: A, determining the ACK/NACK channel mapped by an existing physical downlink control channel in accordance with a rule of evenly using an ACK/NACK channel on an uplink cell carrier (CC); and B, feeding back the ACK/NACK information by a terminal based on the determined ACK/NACK channel. By using the method, the average of the ACK/NACK channel mapped by a downlink CC can be realized easily without exerting extra limitations by a base station, thus greatly improving the scheduling flexibility.

Description

Method for determining ACK/NACK channel

Technical Field

The present invention relates to wireless communication technologies, and in particular, to a method for determining an acknowledgement/negative acknowledgement (ACK/NACK) channel.

Background

In an enhanced long term evolution (LTE-a) system, in order to support a higher transmission rate, a Carrier Aggregation (Carrier Aggregation) technology is proposed, specifically: a larger operating bandwidth is obtained by combining a plurality of Component Carriers (CCs) to constitute the downlink and uplink of the communication system. For example, to support a bandwidth of 100MHz, it can be obtained by combining 5 CCs of 20 MHz.

The data transmission in the LTE-a system is similar to the LTE system, and is based on hybrid automatic repeat request (HARQ), and specifically includes: and the data receiving side determines whether the data is correctly received, and if so, feeds back ACK information, and if not, feeds back NACK information. Here, the ACK/NACK information is transmitted on an ACK/NACK channel of a Physical Uplink Control Channel (PUCCH). Therefore, it can be seen that, when feeding back ACK/NACK information, the ACK/NACK channel that needs to be used is first determined. The following describes a method for determining an ACK/NACK channel to be used in both cases of a symmetric carrier and an asymmetric carrier, respectively.

Referring to fig. 1, fig. 1 is a schematic diagram of symmetrical carrier combination. Here, the symmetrical carrier combination is substantially equal in the number of uplink CCs and downlink CCs, that is, the uplink CCs and the downlink CCs are associated one by one. In the prior art, a method for determining an ACK/NACK channel is provided for a symmetric carrier combination, which mainly includes: aiming at each downlink CC, the downlink CC is enabled to send system broadcast information carrying identification information (specifically indexes of ACK/NACK channels and the like) of ACK/NACK channels distributed on the associated uplink CC; and then, allocating an ACK/NACK channel on the uplink CC associated with the downlink CC according to the system broadcast information.

Here, the asymmetric carrier combination is that the number of uplink CCs is not equal to that of downlink CCs, and the specific implementation may be divided into two cases, where one case is asymmetry of a service, and specifically: the number of downlink CCs configured in one cell is more than that of uplink CCs, that is, ACK/NACK channels of a plurality of downlink CCs need to be allocated in one uplink CC; the other situation is as follows: regardless of whether the number of uplink and downlink CCs configured in a cell is equal, a user-specific asymmetric carrier combination may be configured, for example, a terminal receives PDSCH on multiple downlink CCs simultaneously, and transmits uplink signals on only one uplink CC, so as to save power for the terminal. Based on the above two cases, the following describes a method for determining an ACK/NACK channel in asymmetric carrier combination in the prior art.

Taking the schematic diagram of asymmetric carrier combination shown in fig. 2 as an example, as shown in fig. 2, since the number of uplink CCs is only 1, and the number of downlink CCs is greater than 1, it is necessary to allocate ACK/NACK channels corresponding to a plurality of downlink CCs in one uplink CC. In order to control the overhead of the ACK/NACK channel to the maximum extent, the terminal adopts the same method to determine the corresponding ACK/NA aiming at all downlink CCsThe CK channel. Such as the existing LTE FDD ACK/NACK channel determination method, $n_{\mathrm{PUCCH}}^{\left(1\right)}=n_{\mathrm{CCE}}+N_{\mathrm{PUCCH}}^{\left(1\right)},$ wherein n is_CCEIs an index of a Control Channel Element (CCE) included in a downlink CC, n_PUCCH ⁽¹⁾Index of ACK/NACK channel mapped for this CCE, N_PUCCH ⁽¹⁾Parameters are configured for the higher layers. Thus, according to the "tree" structure adopted when combining PDCCHs with CCEs in LTE, that is, for PDCCHs consisting of m CCEs, m is 1, 2, 4, 8, it can only start with CCEs with a multiple of m index, and accordingly, UEs scheduled with PDCCHs consisting of m CCEs use ACK/NACK channels with a multiple of m index. It can be seen that for each CC, the respective CCs are actually more inclined to use ACK/NACK channels with indexes of multiples of m (m is greater than 1), that is, the ACK/NACK channels cannot be used on average. In order to avoid collision of ACK/NACK channels for scheduling data on each CC, more restrictions are required to be imposed by the base station, which obviously is not beneficial to improve scheduling flexibility.

Disclosure of Invention

The invention provides a method for determining an ACK/NACK channel in a wireless communication system applied to asymmetric carrier combination, so as to be beneficial to improving the scheduling flexibility.

The technical scheme provided by the invention is realized by the following operations:

a method for determining an ACK/NACK channel in a wireless communication system with asymmetric carrier combination comprises the following steps:

a, determining an ACK/NACK channel mapped by a current PDCCH according to a principle of uniformly using the ACK/NACK channel on an uplink CC;

and B, the terminal feeds back the ACK/NACK information through the determined ACK/NACK channel.

It can be seen from the above technical solutions that, in the method for determining ACK/NACK channels applied to an asymmetric carrier combination wireless communication system provided by the present invention, when determining ACK/NACK channels mapped by a PDCCH, the ACK/NACK channels are determined according to a principle of uniformly using ACK/NACK channels on an uplink CC, so that it is easy to implement averaging of ACK/NACK channels mapped by downlink CCs, and a technical problem that each CC tends to use ACK/NACK channels with indexes that are multiples of m (m is greater than 1) in the prior art is avoided, which is obviously beneficial to improving scheduling flexibility.

Drawings

FIG. 1 is a diagram illustrating symmetrical carrier combination in the prior art;

FIG. 2 is a diagram illustrating asymmetric carrier combination in the prior art;

FIG. 3 is a first schematic view of a first embodiment of the present invention;

FIG. 4 is a second schematic view of the first embodiment of the present invention;

FIG. 5 is a third schematic view of the first embodiment of the present invention;

FIG. 6 is a schematic view of a second embodiment of the present invention;

fig. 7 is a schematic view of a third embodiment of the present invention.

Detailed Description

The method for determining the ACK/NACK channel applied to the wireless communication system of the asymmetric carrier combination provided by the embodiment of the invention has the central idea that: and determining the ACK/NACK channel mapped by the current PDCCH according to the principle of averaging the use probability of the ACK/NACK channel on the uplink CC according to the number of CCEs contained in the current PDCCH and the number of the allocated ACK/NACK channels in the uplink CC. Then, the terminal may feed back ACK/NACK information through the determined ACK/NACK channel, and the base station may also receive the ACK/NACK information fed back by the terminal through the determined ACK/NACK channel.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments. For convenience of description, the following embodiments are described by taking as an example a case where a PDCCH is transmitted on the basis of a plurality of downlink CCs and an ACK/NACK is transmitted only in one uplink CC.

The first embodiment:

as shown in fig. 3, in order to reduce the overhead of the PDCCH, in this embodiment, identification information for distinguishing the ACK/NACK channels mapped by the PDCCH is not added to the PDCCH, but the ACK/NACK channels mapped by the PDCCH are determined according to the index of the CCE included in the current PDCCH, the index of the downlink CC where the PDCCH is located, and the number of ACK/NACK channels in the uplink CC. In this embodiment, the index of the downlink CC where the PDCCH is located is mainly used to ensure that PDCCHs in different downlink CCs are mapped to different ACK/NACK channels on the uplink CC.

In this embodiment, assuming that it is not necessary to map a CCE on a downlink CC where a current PDCCH is located to a continuous ACK/NACK channel in an uplink CC, determining the ACK/NACK channel mapped by the current PDCCH in this embodiment specifically includes:

firstly, a CCE on a downlink CC is dispersedly mapped on an ACK/NACK channel allocated in an uplink CC to obtain a temporary ACK/NACK channel index n_PUCCH. With the uplink index of the downlink CC as n_CCETaking CCE of (1) as an example, then n_PUCCHThis can be achieved by the following equation 1:

or

(formula 1)

Wherein，

Denotes lower rounding, N_CCE，kIf the value of the PCFICH corresponding to the current PDCCH is equal to k, the total number of CCEs contained in the downlink CC where the current PDCCH is located is N, and if the overhead of the PCFICH and the PHICH is ignored_CCE，kCan be as follows:

N_RB ^DLis the total number of Physical Resource Blocks (PRBs), N, within the system bandwidth_sc ^RBIs the number of subcarriers within one PRB; n is a radical of_ANInformation of the number of ACK/NACK channels allocated on the uplink CC, the N_ANMay be transmitted to the terminal through higher layer signaling such as broadcast signaling or RRC signaling, or the N_ANNot by dedicated signalling, but implicitly by other methods, e.g. specifying N_ANEqual to the maximum number of CCEs on the pre-designated main downlink CC corresponding to the uplink CC, i.e. the number of CCEs when the physical control channel is transmitted by 3 OFDM symbols, of course, if the influence of PCFICH and PHICH is ignored, N_ANThis can be estimated by equation 2:

(formula 2)

Next, for each CCE on the CC where the current PDCCH is located, according to the index of the temporary ACK/NACK channel mapped by the CCE and the offset value corresponding to the CC where the current PDCCH is located, finally determining the index n of the ACK/NACK channel mapped by the CCE_PUCCH ⁽¹⁾This can be determined by equation 3:

$n_{\mathrm{PUCCH}}^{\left(1\right)}=n_{\mathrm{PUCCH}}+f\left(i_{\mathrm{CC}}\right)+N_{\mathrm{PUCCH}}^{\left(1\right)}$ or

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(n_{\mathrm{PUCCH}}+f\left(i_{\mathrm{CC}}\right))\mathrm{mod}{N}_{\mathrm{AN}}+N_{\mathrm{PUCCH}}^{\left(1\right)}$ (formula 3)

Wherein N is_PUCCH ⁽¹⁾Parameter configured for higher layers, f (i)_CC) Is the offset value, i, corresponding to the downlink CC where the current PDCCH is located_CCIs an index of the downlink CC.

It should be noted that, in this embodiment, the offset value corresponding to the downlink CC is already set when executing this step, and there may be a variety of ways for implementing this step specifically, for example: one way is to set different offset values for all downlink CCs respectively, which can be expressed by the following formula 3-1:

f(i_CC)＝c·i_CC(ii) a (formula 3-1)

Another way is to configure the same offset value for more than one downlink CC, that is, the number of set offset values is greater than 1 but less than the total number of downlink CCs, which can be represented by the following formula 3-2:

f(i_CC)＝c·mod(i_CCp), (formula 3-2)

Here, P is the number of offset values set.

In the above formula 3-1 or formula 3-2, the parameter c is a predefined value, or may be a semi-statically configured value, for example, c is equal to 1; alternatively, c may be equal to 2 or a multiple of 2, considering that the UE may occupy two ACK/NACK channels adjacent in index to feed back ACK/NACK information. Thus, when the step is executed, the offset value corresponding to the downlink CC where the PDCCH is located at present is searched from the offset values corresponding to the preset downlink CCs.

It should be noted that, in the above, taking the example that the CCE on the CC where the current PDCCH is located is not mapped to the continuous ACK/NACK channel in the uplink CC, preferably, as an extension of the embodiment of the present invention, assuming that the CCE on the CC where the current PDCCH is located needs to be mapped to the continuous ACK/NACK channel in the uplink CC, the specific operation is similar to the above, that is, the CCE index n is determined first_CCEMapped temporary ACK/NACK channel index n_PUCCHHere, since the CCE on one CC where the current PDCCH is located is mapped to the continuous ACK/NACK channel in the uplink CC in this embodiment, n is n_PUCCH＝n_CCE. And then combining an offset value f (i) corresponding to the downlink CC where the current PDCCH is located_CC) To obtain the final mapped ACK/NACK channel index n_PUCCH ⁽¹⁾Specifically, it is shown by the following formula 3-3:

$n_{\mathrm{PUCCH}}^{\left(1\right)}=n_{\mathrm{CCE}}+f\left(i_{\mathrm{CC}}\right)+N_{\mathrm{PUCCH}}^{\left(1\right)},$ or

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(n_{\mathrm{CCE}}+f\left(i_{\mathrm{CC}}\right))\mathrm{mod}{N}_{\mathrm{AN}}+N_{\mathrm{PUCCH}}^{\left(1\right)}$ (formula 3-3)

Note that, since the PCFICH of each downlink CC is dynamically set, that is, the number of CCEs of each downlink CC is dynamically changed, in order to fully utilize all ACK/NACK channels of the uplink CC, the offset value f (i) is set_CC) It is also necessary to ensure that CCEs on each downlink CC are mapped to different ACK/NACK channels as much as possible when the PCFICH of each downlink CC takes a relatively small value (for example, the PCFICH is equal to 1), that is, the CCEs can be fully mapped to all ACK/NACK channels of the uplink CC, and based on this, f (i) calculated in formula 3-1 or formula 3-2 can be set_CC) The time parameter c is equal to or approximately equal to the value of the CCE when one OFDM symbol transmits the physical control channel $c_0=N_{\mathrm{CCE}}^{\left(1\right)},$ Of course, if the influence of PCFICH and PHICH is neglected, N_CCE ⁽¹⁾Can be estimated as

As another way to set the parameter c in the embodiment of the present invention, the number information N of ACK/NACK channels included in the uplink CC may also be set_ANIs equally divided into N_CCIn which N is_CCThe number of downlink CCs configured for the base station, the parameter c is equal to or approximately equal to the value of one ACK/NACK channel (denoted as c)₀') to note this value as

Those skilled in the art know that CCEs in LTE are combined in a tree structure when combining PDCCHs, i.e., for PDCCHs comprising m CCEs, it can only start with CCEs with indices that are multiples of m, and the UE uses only ACK/NACK channels mapped by CCEs with the smallest index of the PDCCH, which results in that ACKs/NACKs corresponding to CCEs with indices that are multiples of m (m is greater than 1, e.g., 2, 4, and 8) are used with a greater probability. Based on this, N can be adjusted in the present embodiment_ANAnd c, balancing ACK/NAC of uplink CCWhen the load of the K channels is thus reduced to reduce the scheduling restriction, N may be configured, for example_ANIs even and the parameter c is odd, so that the index i can be guaranteed_CCEven numbered CCs tend to use even numbered ACK/NACK channels, while index i_CCOdd numbered CCs tend to use odd numbered ACK/NACK signals. Based on this, according to the above description, the parameter c in the present embodiment can be finally determined to be close to the above c₀Or c₀An odd number of e.g.

Or

By the above operation, the method for determining the CCE mapping ACK/NACK channel included in the downlink CC according to the embodiment of the present invention is implemented.

In consideration of the application of the embodiment of the present invention, the inventor of the present application further provides several specific extension ways of the embodiment, and the following three ways are taken as examples to describe, and it should be noted that the three ways are only an example and do not limit the application of the embodiment of the present invention.

The first mode is as follows:

as shown in fig. 4, in order to further implement mapping of the same CCE index in different downlink CCs to different ACK/NACK channels, on the basis of the foregoing embodiment, the method further determines the ACK/NACK channel mapped by the PDCCH according to an identifier of the terminal UE, such as a UE ID, and specifically includes: determining the index n of the ACK/NACK channel mapped by the appointed CCE according to the index (for example, the CCE with the smallest index) of the appointed CCE contained in the current PDCCH, the UE ID of the terminal receiving the PDCCH, the index of the downlink CC where the current PDCCH is located and the number of the allocated ACK/NACK channels in the uplink CC_PUCCH ⁽¹⁾。

Here, let the UE ID of the terminal receiving PDCCH be n_RNTIThe index of the downlink CC where the current PDCCH is located is i_CCThe index of the designated CCE is n_CCEFor example, the index n of the ACK/NACK channel is determined as described above_PUCCH ⁽¹⁾The method is realized by formula 4:

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(Y_k+n_{\mathrm{CCE}})\mathrm{mod}{N}_{\mathrm{AN}}+f\left(i_{\mathrm{CC}}\right)+N_{\mathrm{PUCCH}}^{\left(1\right)}$ or

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(Y_k+n_{\mathrm{CCE}}+f\left(i_{\mathrm{CC}}\right))\mathrm{mod}{N}_{\mathrm{AN}}+N_{\mathrm{PUCCH}}^{\left(1\right)};$ (formula 4)

Wherein, f (i)_CC) Specifically, the offset value corresponding to each downlink CC is calculated as described in the above formula 3-1 or 3-2, which is not described herein again; y is_kY is determined by the UE ID if the same mapping method is used within each subframe_k＝n_RNTI(ii) a Preferably, in this embodiment, in order to randomize the mapping of the CCE assigned to the ACK/NACK channel in different subframes, the CCE assigned may be mapped to different ACK/NACK channels in different subframes, and Y may be a result of this_kDetermined by the UE ID and subframe number, e.g. using the method of determining UE specific search space in existing LTE, Y_k＝(A·Y_k-1) mod D, in which Y_-1＝n_RNTI≠0，A＝39827，D＝65537and

n_sIs the number of slots within a frame.

This completes the description of the first mode.

The second mode is as follows:

the method is different from the first method, and specifically comprises the following steps:

step 200, determining a specific search space of the terminal in the downlink CC where the PDCCH is located.

Here, step 200 may be performed according to a manner of determining a specific search space in an existing LTE system, and is not described again in this embodiment of the present invention.

Step 201, sequentially setting indexes for the CCEs contained in the specific search space from a preset value.

Here, the preset value may be 0, or other values, such as 1, and the embodiment is not limited.

Step 202, determining the index n of the ACK/NACK channel mapped by each CCE according to the index of the CCE, the index of the CC where the PDCCH is located and the UE ID of the terminal_PUCCH ⁽¹⁾。

The value set in step 201 is n_CCEFor example, the step 202 is implemented by the following formula 5:

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(Y_k+n_{\mathrm{CCE}})\mathrm{mod}{N}_{\mathrm{AN}}+N_{\mathrm{PUCCH}}^{\left(1\right)};$ (formula 5)

Of course, in order to further realize that the same CCE index is mapped to different ACK/NACK channels in different downlink CCs, the above equation 5 may also be replaced by equation 5-1:

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(Y_k+n_{\mathrm{CCE}})\mathrm{mod}{N}_{\mathrm{AN}}+f\left(i_{\mathrm{CC}}\right)+N_{\mathrm{PUCCH}}^{\left(1\right)}$ or

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(Y_k+n_{\mathrm{CCE}}+f\left(i_{\mathrm{CC}}\right))\mathrm{mod}{N}_{\mathrm{AN}}+N_{\mathrm{PUCCH}}^{\left(1\right)}$ (formula 5-1)

It should be noted that, as another embodiment of the present invention, step 202 may be replaced by step 202': according to the existing LTE method, N is used_ANCalculate the starting position of a particular search space for the number of CCEs:

wherein, L is the number of CCEs contained in the current PDCCH; then, in order

As a starting position, the CCE contained from the starting position startsDetermining an index n of an ACK/NACK channel mapped by each CCE in the specific search space_PUCCH ⁽¹⁾. Specifically, it is expressed by the formula 5-2:

or

(formula 5-2)

Preferably, step 202' may further be performed according to an index i of a downlink CC where the current PDCCH is located_CCTo set offset values f (i) of each downlink CC setup mapping, respectively_CC) Thus, equation 5-2 is further replaced with equation 5-3 accordingly:

or

(formula 5-3)

This completes the description of the second mode.

The third mode is as follows:

this embodiment is different from the first and second embodiments, and takes into account the index of the designated PRB included in the PDSCH corresponding to the current PDCCH, for example, the PRB with the smallest index, as specifically shown in fig. 5. In fig. 5, the present embodiment determines the ACK/NACK channel for the index of one designated CCE (e.g., the CCE with the smallest index) included in the current PDCCH, the designated PRB index (e.g., the PRB with the smallest index) included in the corresponding PDSCH, and the index of the downlink CC where the current PDCCH is located. The assigned PRB index included in the PDSCH is n_PRBCurrent PDCCH downThe index of row CC is i_CCThe index of one designated CCE contained in the current PDCCH is n_CCEThe index n of the mapped ACK/NACK channel is determined by the following equation 6_PUCCH ⁽¹⁾：

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(n_{\mathrm{PRB}}+n_{\mathrm{CCE}})\mathrm{mod}{N}_{\mathrm{AN}}+f\left(i_{\mathrm{CC}}\right)+N_{\mathrm{PUCCH}}^{\left(1\right)}$ Or

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(n_{\mathrm{PRB}}+n_{\mathrm{CCE}}+f\left(i_{\mathrm{CC}}\right))\mathrm{mod}{N}_{\mathrm{AN}}+N_{\mathrm{PUCCH}}^{\left(1\right)}$ (formula 6)

Thus, the base station scheduler can realize that the PDCCH on one downlink CC is uniformly mapped to all ACK/NACK channels on the uplink CC by adjusting the appointed PRB index and the CCE index occupied by the current PDCCH; and, the offset f (i) is adopted_CC) And the PDCCH in different downlink CCs can be further ensured to be mapped to different ACK/NACK channels on the uplink CC.

This completes the description of the third mode.

The above is a description of the first embodiment of the present invention, and the following is a description of the second embodiment of the present invention.

Second embodiment:

different from the first embodiment, in this embodiment, in order to further improve flexibility, the ACK/NACK channel mapped by the current PDCCH may be further determined according to information b, which is used to indicate an offset value used when the CCE included in the current PDCCH maps the ACK/NACK channel, where the information b may be carried by the PDCCH, specifically, information b used to distinguish the mapped ACK/NACK channel is added to the PDCCH, or a terminal that needs to determine the ACK/NACK channel mapped by the current PDCCH is notified by using other manners, which is not specifically limited herein.

For convenience of description, in the present embodiment, the information b is carried by the PDCCH as an example, based on this, when determining the ACK/NACK channel mapped by the CCE, the index n of the ACK/NACK channel mapped by the PDCCH may be determined according to the index of the CCE included in the PDCCH and the carried information b, and by combining with a formula for calculating the index of the ACK/NACK channel in the existing LTE FDD_PUCCH ⁽¹⁾Specifically, the following formula 7:

$n_{\mathrm{PUCCH}}^{\left(1\right)}=n_{\mathrm{CCE}}+o\left(b\right)+N_{\mathrm{PUCCH}}^{\left(1\right)}$ (formula 7)

Here, o (b) is an offset value indicated by information b in PDCCH, and is specifically related to the bit occupied by information b, for example, information b is 2-bit information, and then o (b) may take 4 values, for example, 0, 1, 2 and 3. However, with the method defined in o (b), when there are fewer OFDM symbols for transmitting control channels on each CC, the number of CCEs is small, and the PDCCH on this CC can only be mapped to the ACK/NACK channel with a smaller index value in the uplink CC, thereby resulting in uneven load of the ACK/NACK channels allocated in the uplink CC.

To solve the above-mentioned negativeThe problem of uneven load is solved by the invention that according to CCE indexes, the information b for distinguishing the mapped ACK/NACK channel added in the current PDCCH and the index i of the downlink CC where the current PDCCH is positioned_CCAnd the number N of the allocated ACK/NACK channels in the uplink CC_ANTo calculate an ACK/NACK channel index of one PDCCH map. Four preferred modes are described below. It should be noted that the four ways are only examples, and do not limit the application of the embodiments of the present invention.

Mode 1:

in the method 1, according to the index i of the downlink CC where the current PDCCH is located_CCTo obtain the offset value f (i) corresponding to the downlink CC_CC) Wherein the offset value f (i)_CC) The specific setting manner of the offset value f (i) in this embodiment is similar to that in the embodiment, which is not described herein again, and preferably_CC) When the PCFICH of each downlink CC has a relatively small value (for example, the PCFICH is equal to 1), it is required to ensure that CCEs on different downlink CCs are mapped to different ACK/NACK channels as much as possible, that is, can be fully mapped to all ACK/NACK channels of the uplink CC. Then, determining ACK/NACK channel index n of current PDCCH mapping by using the obtained offset value_PUCCH ⁽¹⁾Specifically, the following formula:

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(n_{\mathrm{CCE}}+o\left(b\right))\mathrm{mod}{N}_{\mathrm{AN}}+f\left(i_{\mathrm{CC}}\right)+N_{\mathrm{PUCCH}}^{\left(1\right)}$ or

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(n_{\mathrm{CCE}}+o\left(b\right)+f\left(i_{\mathrm{CC}}\right))\mathrm{mod}{N}_{\mathrm{AN}}+N_{\mathrm{PUCCH}}^{\left(1\right)}.$ (formula 8)

Here, the offset values may be o (b) and N_ANIndependently, for example, if the information b is 2 bits, the offset value o (b) may be 0, 1, 2, 3 or 1, 3, 5, 7, etc.

This completes the description of mode 1.

Mode 2:

here, the mode 2 is based on the number N of ACK/NACK channels allocated in the uplink CC_ANTo configure the offset value o (b), specifically, to distribute the values of o (b) to 0 to N_ANIn this manner, the ACK/NACK channel index n is determined accordingly in this manner_PUCCH ⁽¹⁾Can be replaced with equation 9:

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(n_{\mathrm{CCE}}+o\left(b\right))\mathrm{mod}{N}_{\mathrm{AN}}+N_{\mathrm{PUCCH}}^{\left(1\right)}.$ (formula 9)

In order to distribute the values of o (b) to 0 to N_ANIn the above aspect, in the present embodiment 2, o (b) may be defined as o (b) ═ b · N_CCE，1Or

Wherein N is_CCE，1Is only in the first OFDM symbolThe value of CCE when a physical control channel is signaled, where if the effects of PCFICH and PHICH are ignored, this value can be estimated as

Wherein N is_bN is the number of values allowed for the information b, specifically b ═ 0, 1_bE.g. information b is 2 bits of information, then N_bEqual to 4.

It should be noted that, since o (b) is required to be used in determining the ACK/NACK channel index mapped to each CCE, and N used in determining o (b) is determined according to the above description_bIs the number of allowed values of the information b, specifically 0, 1_b-1, so that the ACK/NACK channel mapped by each CCE is distributed to all ACK/NACK channels on the uplink CC. Therefore, the base station can control the ACK/NACK channel actually occupied by the current PDCCH by adjusting the information b, so that the load averaging of the ACK/NACK channel on the uplink CC is achieved, and the scheduling limitation and interference are reduced.

Preferably, in order to avoid extra scheduling restriction caused by mapping CCEs with the same index in different downlink CCs to the same ACK/NACK channel, the index i of the CC where the current PDCCH is located may be further determined according to_CCTo obtain the offset value f (i) of different downlink CCs in mapping ACK/NACK channel_CC) As shown in fig. 6 in particular, equation 9 may thus be replaced with equation 9 below:

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(n_{\mathrm{CCE}}+o\left(b\right))\mathrm{mod}{N}_{\mathrm{AN}}+f\left(i_{\mathrm{CC}}\right)+N_{\mathrm{PUCCH}}^{\left(1\right)}$ or

$n_{\mathrm{PUCCH}}^{\left(1\right)}=(n_{\mathrm{CCE}}+o\left(b\right)+f\left(i_{\mathrm{CC}}\right))\mathrm{mod}{N}_{\mathrm{AN}}+N_{\mathrm{PUCCH}}^{\left(1\right)}.$ (formula 9)

This completes the description of mode 2.

Mode 3:

the embodiment 3 is specifically realized by the following steps:

step 300, according to the total number N of CCEs currently contained in the downlink CC where the current PDCCH is located_CCE，kAnd the number N of ACK/NACK channels distributed in the uplink CC_ANAnd calculating the initial position information of the ACK/NACK channel mapped by one CCE in the downlink CC.

Here, the calculation principle is specifically to distribute ACK/NACK channels mapped by CCEs of the CC where the PDCCH is located to ACK/NACK allocated in the uplink CC. For example, the index in step 300 is n_CCEThe starting position of the ACK/NACK mapped by the CCE of (1) is represented by the following formula:

step 301, calculating an index n of an ACK/NACK channel mapped by the CCE according to the calculated initial position information and the offset value o (b) of the CCE indicated by the information b carried by the PDCCH_PUCCH ⁽¹⁾。

Here, in step 301, the offset values may be o (b) and N_ANIndependently, e.g., information b is 2 bits, then the offset value o (b) is 0, 1, 2, 3 or 1, 3, 5, 7, etc., such that the ACK determined in this step 301 is ≧ HIndex n of NACK channel_PUCCH ⁽¹⁾Comprises the following steps:

or

(formula 10)

Preferably, in order to avoid extra scheduling restriction caused by mapping CCEs with the same index in different downlink CCs to the same ACK/NACK channel, the index i of the CC where the current PDCCH is located may be further determined according to_CCTo obtain the offset value f (i) of different downlink CCs in mapping ACK/NACK channel_CC). Thus, equation 10 can be replaced with equation 10' below:

or

(formula 10)

This completes the description of mode 3.

Mode 4:

this mode is similar to the second mode of the first embodiment, and specifically includes the following steps:

step 400, determining a specific search space of the terminal in the CC where the current PDCCH is located.

Step 401, sequentially setting indexes for CCEs contained in the specific search space from a preset value.

Step 402, according to the existing LTE method, using N_ANCalculating a specific for the number of CCEsThe starting position of the search space.

Here, step 402 may be calculated by the following formula:

where L is the number of CCEs included in the PDCCH.

Step 403, for the start position calculated from step 402, according to the index n of the CCE_CCEAnd an offset value o (b) determining an index n of the ACK/NACK channel to which the CCE is mapped_PUCCH ⁽¹⁾。

Here, step 403 is implemented by equation 11:

or

(formula 11)

Preferably, in order to avoid extra scheduling restriction caused by mapping CCEs with the same index in different downlink CCs to the same ACK/NACK channel, the index i of the CC where the current PDCCH is located may be further determined according to_CCTo change the index of the mapped ACK/NACK channel, thus, equation 11 can be replaced with the following equation 11':

or

(formula 11)

This completes the description of equation 4.

The above is a description of the second embodiment of the present invention, and the following is a description of the third embodiment of the present invention.

The third embodiment:

compared with the first embodiment and the second embodiment, the present embodiment is simpler, and specifically includes: when ACK/NACK channels corresponding to PDCCHs of multiple downlink CCs are transmitted on the same CC, as shown in fig. 7, two groups of ACK/NACK channels are allocated on the uplink CC, where a first group of ACK/NACK channels and a CCE of a downlink CC designated as a main downlink CC have a one-to-one mapping relationship, so that HARQ transmission of LTE UEs and higher-level UEs in the main downlink CC can be achieved, and it should be noted that a method of mapping ACK/NACK channels using CCEs defined in LTE may be adopted to satisfy backward compatibility; and the second group of ACK/NACK channels is mapped with CCEs of other downlink CCs except the primary downlink CC, and based on this, determining the mapped ACK/NACK channels in this embodiment specifically includes: firstly, determining whether a CC where a current PDCCH is located is a designated downlink CC serving as a main downlink CC, and if so, determining an ACK/NACK channel mapped by the PDCCH according to a principle that the main downlink CC and one of two groups of ACK/NACK channels allocated in the uplink CC are mapped one by one; and if not, determining the ACK/NACK channel mapped by the PDCCH according to a preset mapping method adopted by the downlink CCs except the main downlink CC. Here, the primary downlink CC supports LTE UEs, and downlink CCs other than the primary downlink CC cannot support LTE UEs, based on which mapping from CCEs of the downlink CCs other than the primary downlink CC to ACK/NACK may be redefined, specifically, on the premise that it is ensured that ACK/NACK channels mapped in uplink CCs by PDCCHs scheduled on the respective downlink CCs do not collide, the downlink CCs other than the primary downlink CC may be mapped to the second group of ACK/NACK channels by the same method, for example, the existing LTE method is used for mapping, or the methods provided in the first embodiment or the second embodiment are used.

It can be seen from the above technical solutions that, when determining the ACK/NACK channel mapped by the PDCCH, the ACK/NACK channel mapped by the PDCCH is determined according to the principle of uniformly using the ACK/NACK channel on the uplink CC, so that the ACK/NACK channel mapped by the downlink CC is easily averaged, and the technical problem that each CC in the prior art tends to use the ACK/NACK channel with an index being a multiple of m (m is greater than 1) is avoided, which is obviously beneficial to improving scheduling flexibility.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (15)

1. A method for determining ACK/NACK channel in a wireless communication system with asymmetric carrier combination, the method comprising:

a, determining an ACK/NACK channel mapped by a current PDCCH according to a principle of uniformly using the ACK/NACK channel on an uplink Cell Carrier (CC);

and B, the terminal feeds back the ACK/NACK information through the determined ACK/NACK channel.

2. The method of claim 1, wherein the determining in step a comprises:

a1, determining an offset value corresponding to a downlink CC where a current PDCCH is located;

a2, determining the ACK/NACK channel mapped by the PDCCH according to the number of the allocated ACK/NACK channels in the uplink CC, the offset value corresponding to the downlink CC where the current PDCCH is located, which is determined in the step A1, and the index of a control channel element CCE contained in the PDCCH.

3. The method according to claim 2, wherein said step a2 comprises:

step A21, calculating index n of ACK/NACK channel allocated in uplink CC temporarily mapped by each CCE contained in the PDCCH_PUCCH；

Step A22, aiming at each CCE contained in the PDCCH, according to the index n of the ACK/NACK channel temporarily mapped by the CCE_PUCCHAnd the number N of the distributed ACK/NACK channels in the uplink CC_ANAnd determining the index n of the ACK/NACK channel finally mapped by the CCE according to the offset value corresponding to the downlink CC where the PDCCH is positioned_PUCCH ⁽¹⁾。

4. The method according to claim 3, wherein said step A21 is calculated according to a principle that each CCE included in said PDCCH is mapped to ACK/NACK channel in a distributed manner, and is specifically implemented by the following formula:

or

Wherein,

denotes lower rounded, n_CCEIs an index of CCE contained in the PDCCH, N_CCE，kWhen the value of the physical format indicator channel PCFICH corresponding to the PDCCH is k,the total number of CCEs in the downlink CC where the PDCCH is located;

the step A22 is represented by the following formula

$n_{\mathrm{PUCCH}}^{\left(1\right)}=n_{\mathrm{PUCCH}}+f\left(i_{\mathrm{CC}}\right)+N_{\mathrm{PUCCH}}^{\left(1\right)}$ Or $n_{\mathrm{PUCCH}}^{\left(1\right)}=(n_{\mathrm{PUCCH}}+f\left(i_{\mathrm{CC}}\right))\mathrm{mod}{N}_{\mathrm{AN}}+N_{\mathrm{PUCCH}}^{\left(1\right)}$ The implementation is carried out; wherein, f (i)_CC) Is an offset value, i, corresponding to the downlink CC where the PDCCH is located_CCIs an index of the CC in which the PDCCH is located, N_PUCCH ⁽¹⁾Parameters are configured for the higher layers.

5. The method according to claim 3, wherein said step A21 is calculated according to a principle that each CCE included in said PDCCH is mapped to consecutive ACK/NACK channels;

in the step A22, the determined offset value and N are adjusted_ANAnd using the following formula

$n_{\mathrm{PUCCH}}^{\left(1\right)}=n_{\mathrm{CCE}}+f\left(i_{\mathrm{CC}}\right)+N_{\mathrm{PUCCH}}^{\left(1\right)}$ Or $n_{\mathrm{PUCCH}}^{\left(1\right)}=(n_{\mathrm{CCE}}+f\left(i_{\mathrm{CC}}\right))\mathrm{mod}{N}_{\mathrm{AN}}+N_{\mathrm{PUCCH}}^{\left(1\right)}$ And (5) realizing.

6. The method according to claim 4 or 5, wherein in step a1, the predetermined offset values corresponding to the downlink CCs are set according to a principle that all downlink CCs correspond to different offset values, which is specifically implemented by the following formula: offset value f (i)_CC)＝c·i_CC(ii) a Or,

the method is implemented by the following formula according to the principle that more than one downlink CC corresponds to the same offset value:

f(i_CC)＝c·mod(i_CC，P)

wherein i_CCP is the number of offset values set, c is a preset value, or a semi-statically configured value.

7. The method of claim 6, wherein c is an odd number,

the number of CCEs used for transmitting the physical control channel in one OFDM symbol is determined; or

Number N of ACK/NACK channels allocated in the uplink CC_ANIs equally divided into N_CCWhen being divided, N is_CCThe number of downlink CCs configured for the base station is determined by the number of any ACK/NACK channels.

8. The method of claim 1, wherein the determining in step a comprises:

determining the ACK/NACK channel mapped by the appointed CCE according to the index of the appointed CCE contained in the PDCCH, the index of the downlink CC where the PDCCH is located, the number of the allocated ACK/NACK channels in the uplink CC and the ID (identity) of the UE of the terminal; or,

determining a specific search space of the terminal in the downlink CC where the PDCCH is located, and sequentially setting indexes for CCEs contained in the specific search space from a preset value;

then, aiming at each CCE contained in the specific search space, determining an ACK/NACK channel mapped by the CCE according to the index of the CCE, the index of the downlink CC where the PDCCH is located and the ID of the terminal, namely the UE; or, calculating the starting position of the specific search space, and sequentially determining the ACK/NACK channel mapped by each CCE in the specific search space from the CCE contained in the starting position.

9. The method of claim 1, wherein the determining in step a comprises:

a0, determining the ACK/NACK channel mapped by the PDCCH according to the index of the appointed CCE contained in the PDCCH, the index of the appointed PRB in the physical downlink shared control channel PDSCH corresponding to the PDCCH and the index of the downlink CC where the PDCCH is located.

10. The method of claim 1, wherein the determining in step a comprises:

a3, determining the ACK/NACK channel mapped by the PDCCH according to the information b of the offset value used for indicating the mapping of the ACK/NACK channel by the CCE contained by the PDCCH, the index of the downlink CC where the PDCCH is located and the number of the ACK/NACK channels distributed in the uplink CC.

11. The method of claim 10, wherein information b indicating an offset value used when CCEs contained in the PDCCH map ACK/NACK channels is carried by the PDCCH.

12. The method according to claim 10 or 11, wherein the offset values used for mapping ACK/NACK channels on CCEs contained in the PDCCH are distributed from 0 to N_ANIs determined by the principle of

Or N_CCE ⁽¹⁾B, determining;

wherein,denotes lower rounding, N_ANNumber of allocated ACK/NACK channels in uplink CC, N_bThe number of allowed values of the information b carried by the PDCCH, N_CCE ⁽¹⁾Is the number of CCEs when the physical control channel is transmitted in the first OFDM symbol.

13. The method according to claim 10 or 11, wherein said step a3 comprises:

calculating the initial position information of the ACK/NACK channel mapped by the CCE in the downlink CC according to the total number of the CCE contained in the downlink CC in which the PDCCH is positioned and the number of the ACK/NACK channels distributed in the uplink CC;

and for each CCE contained in the downlink CC, calculating the identifier of the ACK/NACK channel mapped by the CCE according to the initial position information and the deviant value of the CCE indicated by the information b, and determining the ACK/NACK channel identified as the calculated identifier as the ACK/NACK channel mapped by the CCE.

14. The method according to claim 10 or 11, wherein said step a3 comprises:

determining a specific search space of the terminal in the CC where the PDCCH is located, and sequentially setting indexes for CCEs contained in the specific search space from a preset value; calculating the starting position of the specific search space, calculating the identifier of the ACK/NACK channel mapped by the CCE according to the index of the CCE and the offset value of the CCE indicated by the information b for each CCE from the starting position in the CC where the PDCCH is located, and determining the ACK/NACK channel identified as the calculated identifier as the ACK/NACK channel mapped by the CCE.

15. The method of claim 1, wherein the determining in step a comprises:

determining whether the CC where the PDCCH is located is a designated downlink CC serving as a main downlink CC, and if so, determining the ACK/NACK channel mapped by the PDCCH according to a principle that the main downlink CC and one ACK/NACK channel of two groups of ACK/NACK channels allocated in the uplink CC are mapped one by one; and if not, determining the ACK/NACK channel mapped by the PDCCH according to a preset mapping method adopted by the downlink CCs except the main downlink CC.

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