CN103988563B - Method and device for mapping search space of downlink control channel - Google Patents

Abstract

The embodiment of the invention provides a mapping method and a device of a search space of a downlink control channel, wherein the method comprises the following steps: determining a search space allocated to a downlink control channel (PDCCH) according to a resource allocation mode; and mapping each candidate position (candidate) of the PDCCH to a time-frequency resource corresponding to the search space by taking a resource block RB as an interval. According to the method and the device provided by the embodiment of the invention, the frequency selective scheduling gain is obtained by mapping different candidates of the PDCCH to different RBs, so that the performance of the PDCCH is improved.

Description

Method and device for mapping search space of downlink control channel

technical field

The present invention relates to wireless communication technologies, and more specifically, to a mapping method and device for a search space of a downlink control channel in an LTE (Long Term Evolution, long-term evolution)/LTE-A (LTE-Advanced, enhanced long-term evolution) system.

Background technique

With the evolution of the EUTRA (Evolved Universal Terrestrial Radio Access, Evolved Universal Terrestrial Radio Access) network, many new scenarios appear, such as heterogeneous networks with the same or different cell IDs. New characteristics of data channel and control channel shall be introduced. For the enhanced PDCCH (Physical Downlink ControlChannel, physical downlink control channel), the following needs to be considered:

Ability to support increased control channel capacity;

Can support frequency domain ICIC (Inter-Cell Interference Coordination, inter-cell interference cancellation technology);

It can improve the space reuse of control channel resources;

Capable of supporting beamforming and/or diversity;

Able to operate on new carrier types and MBSFN ((Multicast Broadcast Single Frequency Network, Multicast Broadcast Single Frequency Network) subframes;

It can coexist with a traditional UE (User Equipment, user equipment) on the same carrier.

Desired features include the ability to have scheduling frequency selection and the ability to mitigate inter-cell interference. Based on the above requirements, the E-PDCCH (Enhanced-PDCCH, enhanced PDCCH) can be located in the traditional PDSCH (Physical Downlink Shared Channel, physical downlink shared channel) area. One of the main problems that E-PDCCH is located in the traditional PDSCH area is the design of the search space. The UE blindly detects its E-PDCCH in the area allocated to it by the network. This area can be semi-statically configured through high-layer signaling, or dynamically configured through layer 1 signaling. For E-PDCCH, there are mainly two mapping schemes, namely, local mapping and distributed mapping. For local mapping, it is hoped to obtain frequency selective scheduling gain and frequency selective beamforming gain, that is, eNB (base station) can transmit E-PDCCH on subcarriers with better channel response.

In the existing system, the search space includes multiple candidate positions (candidates) with different aggregation levels (Aggregation Level), as shown in Table 1, for each aggregation level, multiple candidate positions are configured. How to map multiple candidate positions to the search space to obtain frequency selective scheduling gain or frequency diversity gain is very important for E-PDCCH.

In Rel-10v10.0.0 of the LTE system, the function of the search space is defined as follows:

Among them, Y _k is a UE-specific parameter related to C-RNTI (Cell Radio Network Temporary Identifier, cell radio network temporary identifier), i=0,...,L-1, N _{CCE, k} is the control area of subframe k The total number of CCEs (ControlChannel Elements, Control Channel Elements).

Through this function, the starting point of each UE's search space can be determined using UE-specific parameters. However, considering that the parameter _Yk is only related to the number of subframes and C-RNTI, it cannot be guaranteed that the search space includes subcarriers with good channel quality. Therefore, frequency scheduling gain cannot be obtained.

In order for UE to obtain frequency scheduling gain, E-PDCCH resources should be configured through UE-specific high-layer signaling or dynamically configured. If the E-PDCCH resource is configured through high-level signaling, it is very important to design the search space to support at least one candidate position on a carrier with better channel quality. If the existing search space function is reused, multiple candidate positions are mapped to adjacent subcarriers, for example, 4 candidate positions are mapped to the same resource block, which may limit the experience of all candidate positions for E-PDCCH The same channel fades, therefore, no frequency scheduling gain can be obtained.

It should be noted that the above introduction of the technical background is only for the convenience of a clear and complete description of the technical solution of the present invention, and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are known to those skilled in the art just because these solutions are described in the background of the present invention.

Contents of the invention

The purpose of the embodiments of the present invention is to provide a method and device for mapping a search space of a downlink control channel, so as to obtain frequency selective scheduling gain.

According to an aspect of an embodiment of the present invention, a method for mapping a search space of a downlink control channel is provided, wherein the method includes:

Determine the search space allocated for the downlink control channel (PDCCH) according to the resource allocation mode;

Each candidate position (candidate) of the PDCCH is mapped to the time-frequency resource corresponding to the search space at intervals of resource blocks (RB).

According to an aspect of an embodiment of the present invention, a base station is provided, which is used for mapping a search space of a downlink control channel, wherein the base station includes:

A determining unit, which determines the search space allocated for the downlink control channel (PDCCH) according to the resource allocation mode;

The mapping unit maps each candidate position (candidate) of the PDCCH to the time-frequency resource corresponding to the search space at intervals of resource blocks RB.

According to an aspect of an embodiment of the present invention, a computer-readable program is provided, wherein, when the program is executed in the base station, the program causes the computer to execute the aforementioned method for mapping the search space of the downlink control channel in the base station .

According to an aspect of an embodiment of the present invention, a storage medium storing a computer-readable program is provided, wherein the computer-readable program enables a computer to execute the aforementioned downlink control channel search space mapping method in a base station.

The beneficial effect of the embodiment of the present invention is that: by mapping different candidates of the PDCCH into different RBs, a frequency selective scheduling gain is obtained, thereby improving the performance of the PDCCH.

With reference to the following description and accompanying drawings, there are disclosed in detail specific embodiments of the invention, indicating the manner in which the principles of the invention may be employed. It should be understood that embodiments of the invention are not limited thereby in scope. Embodiments of the invention encompass many changes, modifications and equivalents within the spirit and scope of the appended claims.

Features described and/or illustrated with respect to one embodiment can be used in the same or similar manner in one or more other embodiments, in combination with, or instead of features in other embodiments .

It should be emphasized that the term "comprising/comprising" when used herein refers to the presence of a feature, integer, step or component, but does not exclude the presence or addition of one or more other features, integers, steps or components.

Description of drawings

Many aspects of the invention can be better understood with reference to the following figures. The components in the figures are not drawn to scale, merely illustrating the principles of the invention. In order to facilitate illustration and description of some parts of the present invention, corresponding parts in the drawings may be exaggerated or reduced. Elements and features described in one drawing or one embodiment of the present invention may be combined with elements and features shown in one or more other drawings or embodiments. Furthermore, in the drawings, like numerals indicate corresponding parts in the several figures and may be used to indicate corresponding parts used in more than one embodiment. In the attached picture:

FIG. 1 is a flowchart of a method for mapping a search space of a downlink control channel according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of an embodiment of mapping using formula (1) or formula (2);

Fig. 3 is a schematic diagram of another embodiment of mapping using formula (1) or formula (2);

Fig. 4 is the schematic diagram of an embodiment that utilizes formula (3) to map;

Fig. 5 is a schematic diagram of an embodiment of mapping using formula (4);

Fig. 6 is a schematic diagram of an embodiment of mapping using formula (5);

Fig. 7 is a schematic composition diagram of a base station according to an embodiment of the present invention.

detailed description

The foregoing and other features of embodiments of the present invention will become apparent from the following description, with reference to the accompanying drawings. These embodiments are illustrative only, and do not limit the present invention. In order to enable those skilled in the art to easily understand the principle and implementation of the present invention, the implementation of the present invention uses the PDCCH (hereinafter referred to as PDCCH or new PDCCH or E-PDCCH) transmitted in the PDSCH region in the LTE-A system The mapping of the search space of the PDCCH is described as an example, but it can be understood that the embodiment of the present invention is not limited to the above system, and is applicable to other systems or scenarios involving the mapping of the search space of the PDCCH.

Example 1

An embodiment of the present invention provides a method for mapping a search space of a downlink control channel. Fig. 1 is the flowchart of this method, please refer to Fig. 1, this method comprises:

Step 101: Determine the search space allocated for the downlink control channel (PDCCH) according to the resource allocation method;

Step 102: Map each candidate position (candidate) of the PDCCH to the time-frequency resource corresponding to the search space at intervals of resource blocks (RB).

In this embodiment, the PDCCH is used to carry downlink control information (DCI, Downlink Control Information), and is constructed with a control channel element (CCE, Control Channel Element) as the smallest unit. As shown in Table 1, a PDCCH can be composed of L CCEs The value range of L is 1, 2, 4, 8, which represent different aggregation levels (aggregation levels) of the PDCCH, and the L CCEs may be sent at M ^(L) positions.

In this embodiment, the resource allocation mode is, for example, type0, type1, type2, etc., and the search space allocated for the PDCCH can be determined according to different resource allocation modes. For example, based on the type0 resource allocation method, 6 RBGs (Resource Block Group, resource block group) are allocated to PDCCH. According to different system bandwidths, the length (size) of RBGs is different. For example, the system bandwidth is 10MHz, and the RBG size is 3 RBs, it is equivalent to allocating 18 RBs to the PDCCH. For another example, based on the type0 resource allocation method, 3 RBGs are allocated to the PDCCH, if the system bandwidth is 10 MHz, and the RGB size is 3 RBs, it is equivalent to 9 RBs are allocated to the PDCCH. For another example, based on the type2 resource allocation manner, 12 RBs are allocated to the PDCCH. Among them, the resource allocation mode is configured by the system and can be notified to the user through high-level signaling. Wherein, each RB may include multiple CCEs. In this embodiment, each RB includes 4 CCEs as an example for illustration.

The resource allocation methods above are just examples, and the embodiments of the present invention are not limited thereto. With the development of technology, new resource allocation methods may appear, such as the RB-level bitmap method. The method of the embodiment of the present invention can also be used in this resource allocation mode.

In this embodiment, according to different aggregation levels, each candidate position of E-PDCCH is mapped to the allocated E-PDCCH resources through the newly defined unit step size (for example, RB as the step size) to obtain frequency selection Scheduling gain. That is, different candidate positions of the PDCCH are allocated to different time-frequency resources as much as possible, and different parts of a candidate position are allocated to adjacent time-frequency resources.

In one embodiment, if the number M ^(RB) of RBs in the search space allocated for the PDCCH is not less than the number M ^(L) of the candidate positions of the PDCCH, that is, M ^(RB) ≥ M ^(L) , then all Each candidate position of the PDCCH is mapped to different RBs of the time-frequency resource corresponding to the search space.

For example, the number M ^(RB) of RBs in the search space allocated for the PDCCH is 8, then when L=1 or 2, the number M ^(L) of the candidate positions of the PDCCH is 6, satisfying M ^(RB) ≥ M ^{(L )} , that is, if the number of RBs allocated for the PDCCH is sufficient to place all candidate positions of the PDCCH, it is enough to directly map each candidate position of the PDCCH to different RBs.

In one embodiment, if the number M ^(RB) of RBs in the search space allocated for the PDCCH is less than the number M ^(L) of the candidate positions, that is, M ^(RB) <M ^(L) , the The M ^(RB) candidate positions of the PDCCH are mapped to different RBs of the time-frequency resources corresponding to the search space, and then the remaining candidate positions are mapped to different RBs of the time-frequency resources corresponding to the search space in a cyclic shift manner. inside the RB.

For example, the number M ^(RB) of RBs in the search space allocated for the PDCCH is 4, then when L=1 or 2, the number M ^(L) of the candidate positions of the PDCCH is 6, satisfying M ^(RB) <M ^{(L )} , that is, the number of RBs allocated for PDCCH is not enough to place all the candidate positions of PDCCH, then the 4 candidate positions are mapped to these 4 RBs respectively, and then the remaining 2 candidates are The positions are mapped into the first RB and the second RB respectively.

In the embodiments of the present invention, including the above two embodiments, for different aggregation levels, the start points of the candidate positions of the PDCCH may be located in the same RB or in different RBs.

For example, if the starting point of the candidate position of PDCCH is located in the first RB when L=1, then the starting point of the candidate position of PDCCH can be located in the first RB or in the second RB when L=2; similarly , when L=4, the starting point of the candidate position of the PDCCH may be located in the first RB, or may be located in the third RB or the fourth RB. and so on.

In the embodiments of the present invention, including the above two embodiments, for different RBs, PDCCH candidate positions may be mapped to different CCE sequence number positions in different RBs, or may be mapped to the same CCE sequence number positions in different RBs. That is, for each candidate position of the PDCCH mapped to different RBs, the positions of the CCEs on the different RBs are the same or different.

For example, if the first candidate position of PDCCH is mapped to the fourth CCE of the first RB, the second candidate position of the PDCCH can be mapped to the fourth CCE of the second RB, or can be mapped to On other CCEs of the second RB, such as the first CCE; similarly, the third candidate position of the PDCCH can be mapped to the fourth CCE of the third RB, or can be mapped to the third CCE of the third RB. On other CCEs, such as the second CCE; similarly, the fourth candidate position of the PDCCH can be mapped to the fourth CCE of the fourth RB, or can be mapped to other CCEs of the fourth RB, such as On the third CCE. and so on.

Wherein, if M ^(RB) <M ^(L) , then for the above-mentioned "same" situation, the M ^(RB) candidate positions of the PDCCH may have the same position of the CCE on each RB, and the remaining candidate positions may be located in each RB The location of the CCE on the same. For the above "different" situation, it may be that the M ^(RB) candidate positions of the PDCCH have different CCE positions on each RB, and the remaining candidate positions have different CCE positions on each RB.

Wherein, if M ^(RB) ≥ M ^(L) , for the above-mentioned "same" situation, each candidate position of the PDCCH may have the same CCE position on each RB. For the above-mentioned "different" situation, the candidate positions of the number of CCEs contained in one RB can be used as a group, and the positions of the CCEs of the candidate positions in this group are different on each RB. Candidate positions, the positions of the CCEs on each RB are different. Taking the above as an example, M ^(RB) is 8, M ^(L) is 6, and one RB contains 4 CCEs, then the positions of the first 4 candidate positions on the 4 RBs are different, and the last 2 candidate positions cannot be divided into one group, the positions of the two candidate positions on the other two RBs are different.

In this embodiment, if the aggregation level is not greater than the number of control channel elements (CCEs) in each RB, all CCEs of a candidate position of the PDCCH are mapped into the same RB. For example, if the aggregation level L=1 or 2, and one RB contains 4 CCEs, the above relationship is satisfied, and 1 or 2 CCEs contained in one candidate position of the PDCCH are mapped into the same RB. For another example, if the aggregation level L=4 and one RB contains 4 CCEs, the above relationship is satisfied, and the 4 CCEs contained in one candidate position of the PDCCH are mapped into the same RB.

In one embodiment, when for different aggregation levels, the starting points of the candidate positions of PDCCH are located in different RBs, and for different RBs, the candidate positions of PDCCH are mapped to the same CCE sequence number positions in different RBs:

The CCE of the mth candidate position of the PDCCH on the time-frequency resource corresponding to the search space can be determined according to the following formula:

The CCE of the mth candidate position of the PDCCH on the time-frequency resource corresponding to the search space may also be determined according to the following formula:

Wherein, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by a higher layer, which is a parameter used to distinguish the starting position of different users in the E-PDCCH resource. For L=1, it represents the relative offset of the starting CCE relative to the E-PDCCH resource. For example, the E-PDCCH resources are 4 RBs, that is, 16 CCEs, and X _k =1 means starting from the second CCE of the first RB. X _k =10 means starting from the third CCE of the third RB. For L=2, according to the different methods provided by the embodiments of the present invention, the corresponding starting points are different; i=0,...,L-1, L is the aggregation level, N _CCE is the CCE configured for the E-PDCCH The total amount.

In order to make the method of this embodiment clearer and easier to understand, the mapping method of this embodiment will be described below by using specific examples in conjunction with the accompanying drawings.

Fig. 2 is a schematic diagram of mapping of a PDCCH search space according to an embodiment of the present invention. In this embodiment, taking M ^(RB) =4 and X _k =2 as an example, according to formula (1) or formula (2), the mapping result shown in FIG. 2 can be realized.

Referring to FIG. 2, since one RB includes 4 CCEs, when M ^(RB) = 4, N _CCE = 16, that is, 4 RBs are allocated for the PDCCH, and 16 CCEs are numbered 0-15 in total.

When L=1, the PDCCH is composed of 1 CCE. Referring to Table 1, the PDCCH has 6 candidate positions, that is, M ^(L) = 6, that is to say, the CCE of the PDCCH may be in 6 candidate positions Then, each candidate position corresponds to 1 CCE. Since X _k =2, after offsetting two CCEs, the 6 CCEs (logical time-frequency resources) starting from the third CCE (numbered 2) correspond to the 6 candidate positions of the PDCCH. Through the method of this embodiment, the 6 candidate positions are mapped to the 4 RBs corresponding to the physical time-frequency resources with the RB step size, and the numbers on the 10MHz (50 RB) bandwidth shown in Figure 2 are 0,3 ,6,48 within the RB. Since M ^(RB) < M ^(L) is satisfied, the CCEs (candidate positions) numbered 2, 3, 4, and 5 are first mapped to different RBs, and then numbered 6, 7 according to the cyclic shift method. The CCEs (candidate positions) of the CCEs are mapped to the corresponding RBs, where the RBs refer to the RBs corresponding to the physical resources. As shown in Figure 2, map the CCE numbered 2 to the RB numbered 0 of the physical time-frequency resource, map the CCE numbered 3 to the RB numbered 3 of the physical time-frequency resource, and map the CCE numbered 4 to the RB numbered 0 of the physical time-frequency resource. The CCEs numbered 6 are mapped to the RB numbered 6 of the physical time-frequency resource, the CCEs numbered 5 are mapped to the RB numbered 48 of the physical time-frequency resource, and the CCEs numbered 6 are mapped to the numbered physical time-frequency resource In the RB of 0, the CCE numbered 7 is mapped to the RB numbered 3 of the physical time-frequency resource. In this embodiment, each candidate position has the same position on the CCE in each RB, as shown in Figure 2, the CCEs numbered 2, 3, 4, and 5 are all mapped to the third CCE of each RB, The CCEs numbered 6 and 7 are mapped to the fourth CCE of each RB.

Similarly, when L=2, the PDCCH consists of 2 CCEs. Referring to Table 1, the PDCCH has 6 candidate positions, that is, M ^(L) = 6, that is, the two CCEs of the PDCCH may be in 6 candidate positions, each candidate position corresponds to 2 CCEs. Since X _k =2, in this embodiment, after shifting by 4 CCEs, 12 CCEs (logic time-frequency resources) starting from the fifth CCE (numbered 4) correspond to 6 candidate positions of the PDCCH. Through the method of this embodiment, the 6 candidate positions are mapped to the 4 RBs corresponding to the physical time-frequency resources with the RB step size, and the numbers corresponding to the physical time-frequency resources as shown in FIG. 2 are 0, 3, 6, 48 within the RB. Since the starting points of the candidate positions are located in different RBs for different Ls in this embodiment, when L=2, the first candidate position of the PDCCH (CCEs numbered 4 and 5) is mapped to the second RB (corresponding to the physical time In the RB whose frequency resource number is 3, and since M ^(RB) <M ^(L) is satisfied, the numbers are (4,5), (6,7), (8,9), (10, The CCEs (candidate positions) of 11) are mapped to different RBs, and then the CCEs (candidate positions) numbered (12, 13) and (14, 15) are mapped to the corresponding RBs in the manner of cyclic shift. In this embodiment, similar to the aforementioned case of L=1, the positions of the CCEs in each candidate position in each RB are the same, as shown in FIG. 2 , the numbers are (4,5), (6,7), (8 ,9), (10,11) are candidate positions occupying the first and second CCEs of each RB, and candidate positions numbered (12,13) and (14,15) are all occupying the third and second CCEs of each RB. 4 CCEs.

Similarly, when L=4, the PDCCH is composed of 4 CCEs. Referring to Table 1, the PDCCH has 2 candidate positions, that is, M ^(L) = 2, that is, the four CCEs of the PDCCH may be in 2 candidate positions, each candidate position corresponds to 4 CCEs. Since X _k =2, in this embodiment, after offsetting by 8 CCEs, the 8 CCEs starting from the ninth CCE (numbered 8) correspond to the 2 candidate positions of the PDCCH. Through the method of this embodiment, the two candidate positions are mapped to two RBs of the physical time-frequency resource with a step size of RB. Similarly, since the starting points of the candidate positions are located in different RBs for different Ls in this embodiment, when L=4, the starting points (8, 9, 10, 11) of the candidate positions of the PDCCH are mapped to the third RB ( In the RB (numbered 6) corresponding to the physical time-frequency resource, since each candidate position corresponds to 4 CCEs, one candidate position occupies the entire RB.

In the above description, the RBs (respectively numbered 0, 3, 6, and 48) corresponding to the physical time-frequency resources to which each candidate position of the PDCCH is mapped are also examples, which are not limited in this embodiment.

The mapping of the candidate positions of the PDCCH shown in FIG. 2 can be realized through the above formula (1) or formula (2), that is, the CCEs to which each candidate position of the PDCCH is mapped can be determined. In addition, it can be seen from FIG. 2 that through the mapping of formula (1) or formula (2), in each RB, at least one candidate position is allocated, and at most two candidate positions are allocated.

Fig. 3 is a schematic diagram of mapping of a PDCCH search space according to another embodiment of the present invention. In this embodiment, taking M ^(RB) =8 and X _k =3 as an example, according to formula (1) or formula (2), the mapping result shown in FIG. 3 can be realized.

Referring to FIG. 3, since one RB includes 4 CCEs, when M ^(RB) = 8, N _CCE = 32, that is, 8 RBs are allocated for the PDCCH, 32 CCEs in total, numbered 0-31.

When L=1, the PDCCH consists of one CCE. Referring to Table 1, the PDCCH has six candidate positions, that is, M ^(L) =6. Since X _k =3, each candidate position corresponds to 1 CCE, and after shifting by 3 CCEs, the 6 CCEs starting from the fourth CCE (numbered 3) correspond to 6 candidate positions of the PDCCH. Through the method of this embodiment, the 6 candidate positions are mapped to the 8 RBs corresponding to the physical time-frequency resources with the RB step size, and since M ^(RB) ≥ M ^(L) is satisfied, the numbers are directly numbered as 3 and 4 The six CCEs (candidate positions) of , 5, 6, 7, and 8 are mapped to the 6 RBs corresponding to the physical time-frequency resource, and the starting point of the candidate position (that is, the CCE numbered 3) is located at the corresponding physical time-frequency resource Inside the first RB (#1).

Similarly, when L=2, the PDCCH is composed of 2 CCEs. Referring to Table 1, the PDCCH has 6 candidate positions, that is, M ^(L) =6, and each candidate position corresponds to 2 CCEs. In this embodiment, After shifting 6 CCEs, the 12 CCEs starting from the seventh CCE (numbered 6) correspond to 6 candidate positions of the PDCCH. Through the method of this embodiment, the 6 candidate positions are mapped to the 8 RBs corresponding to the physical time-frequency resources with the RB step size. Since the starting points of the candidate positions are located in different RBs for different Ls, the cyclic shift Bit method, the first candidate position (CCE numbered 6,7) is mapped to the second RB (#2) corresponding to the physical time-frequency resource, and so on, numbered as (8,9), ( The CCEs (candidate positions) of 10,11), (12,13), (14,15), and (16,17) are respectively mapped to the numbers corresponding to the physical time-frequency resources as #3, #4, #5, # 6. In the RB of #7 (the positions of the CCEs are the same, both being the 3rd and 4th CCEs).

Similarly, when L=4, the PDCCH is composed of 4 CCEs. Referring to Table 1, the PDCCH has 2 candidate positions, that is, M ^(L) =2, and each candidate position corresponds to 4 CCEs. In this embodiment, After offsetting by 12 CCEs, the 8 CCEs starting from the thirteenth CCE (numbered 12) correspond to the 2 candidate positions of the PDCCH. Through the method of this embodiment, the two candidate positions are mapped to the two RBs corresponding to the physical time-frequency resource at a step size of RB, and the starting point of the candidate position should be mapped to the fourth RB corresponding to the physical time-frequency resource Since each candidate position corresponds to 4 CCEs, one candidate position occupies the entire RB.

In the embodiment of FIG. 3 , the RBs numbered #1 to #6 are not necessarily continuous on the corresponding physical time-frequency resources, for example, they may also be discretely distributed as shown in FIG. 2 . The consecutive numbering in FIG. 3 is to illustrate that at different aggregation levels, the starting points of the candidate positions of the PDCCH are located in different RBs. In the following embodiments, the same situation also exists, for example, the first RB (#1), the second RB (#2), the third RB (#3), and the fourth RB called physical time-frequency resources The meanings of the RB (#4) and so on are the same as those in the embodiment in FIG. 3 , and will not be elaborated one by one.

In another embodiment, when for different aggregation levels, the starting point of the candidate position of PDCCH is located in the same RB, and for different RBs, the candidate position of PDCCH is mapped to the same CCE sequence number position in different RBs:

The CCE of the mth candidate position of the PDCCH on the time-frequency resource corresponding to the search space can be determined according to the following formula:

Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer, which is a parameter used to distinguish the starting position of different users in the E-PDCCH resource, and its meaning is as described above. This will not be repeated here; i=0,...,L-1, L is the aggregation level, and N _CCE is the total number of CCEs configured for the E-PDCCH.

In order to make the method of this embodiment clearer and easier to understand, the mapping method of this embodiment will be described below by using specific examples in conjunction with the accompanying drawings.

Fig. 4 is a schematic diagram of mapping of a PDCCH search space according to an embodiment of the present invention. This embodiment takes M ^(RB) =4, X _k =2 as an example, and according to formula (3), the mapping result shown in FIG. 4 can be realized.

The difference from the mapping result shown in FIG. 2 is that, for different aggregation levels L in this embodiment, the starting points of the candidate positions of the PDCCH are located in the same RB.

Referring to FIG. 4 , when L=1, the starting point of the PDCCH candidate position, that is, the CCE numbered 2 is mapped to the first RB of the physical time-frequency resource. When L=2, the starting point of the candidate position of the PDCCH, that is, the CCE numbered (4,5) is also located in the first RB of the physical time-frequency resource. When L=4, the starting point of the candidate position of the PDCCH, that is, the CCE numbered (8, 9, 10, 11) is also located in the first RB of the physical time-frequency resource.

In another embodiment, when for different aggregation levels, the starting points of the candidate positions of PDCCH are located in different RBs, and for different RBs, the candidate positions of PDCCH are mapped to different CCE sequence number positions in different RBs:

The CCE of the mth candidate position of the PDCCH on the time-frequency resource corresponding to the search space can be determined according to the following formula:

Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer, which is a parameter used to distinguish the starting position of different users in the E-PDCCH resource, and its meaning is as described above. This will not be repeated here; i=0,...,L-1, L is the aggregation level, and N _CCE is the total number of CCEs configured for the E-PDCCH.

In order to make the method of this embodiment clearer and easier to understand, the mapping method of this embodiment will be described below by using specific examples in conjunction with the accompanying drawings.

Fig. 5 is a schematic diagram of mapping of a PDCCH search space according to an embodiment of the present invention. This embodiment takes M ^(RB) =4, X _k =2 as an example, and according to formula (4), the mapping result shown in FIG. 5 can be realized.

Different from the mapping result shown in FIG. 2 , in this embodiment, for different RBs, PDCCH candidate positions are mapped to different CCE sequence number positions.

The difference from the mapping result shown in Figure 4 is that in this embodiment, for different aggregation levels, the starting points of the PDCCH candidate positions are located in different RBs, and for different RBs, the PDCCH candidate positions are mapped to different CCE sequence number positions .

Please refer to Figure 5, when L=1, the starting point of the candidate position of PDCCH, that is, the CCE numbered 2 is mapped to the first RB of the physical time-frequency resource, however, each candidate position of the PDCCH is in each RB For example, the CCE numbered 2 is located at the third CCE of the first RB of the physical time-frequency resource, and the CCE numbered 3 is located at the fourth CCE of the second RB of the physical time-frequency resource. Position, the CCE numbered 4 is located at the first CCE position of the third RB of the physical time-frequency resource, and the CCE numbered 5 is located at the second CCE position of the fourth RB of the physical time-frequency resource. After the CCEs 6 and 7 are mapped according to the cyclic shift, the CCE numbered 6 is located at the fourth CCE position of the first RB of the physical time-frequency resource, and the CCE numbered 7 is located at the second RB of the physical time-frequency resource The location of the first CCE.

Similarly, when L=2, the starting point of the candidate position of the PDCCH, that is, the CCE numbered (4,5) is located in the second RB of the physical time-frequency resource, however, each candidate position of the PDCCH is in each RB The location within is different. For example, the CCE numbered (4,5) is located at the first and second CCE positions of the second RB of the physical time-frequency resource, and the CCE numbered (6,7) is located at the third RB of the physical time-frequency resource The positions of the 3rd and 4th CCEs of the RB, the CCEs numbered (8,9) are located at the 1st and 2nd CCEs of the fourth RB, and the CCEs numbered (10,11) are located at the 1st and 2nd CCEs of the physical time-frequency resources The positions of the 3rd and 4th CCEs of an RB, the CCEs numbered (12,13) are located at the positions of the 3rd and 4th CCEs of the second RB of the physical time-frequency resource, and the CCEs numbered (14,15) The CCEs are located at the positions of the first and second CCEs of the third RB of the physical time-frequency resource. Wherein, since each candidate position corresponds to 2 CCEs, and one RB contains 4 CCEs, therefore, for the case of L=2, the term "each candidate position of PDCCH has a different position in each RB" refers to consecutive The positions of the two candidate positions are different within their respective RBs.

Similarly, when L=4, the starting point of the PDCCH candidate position, that is, the CCE numbered (8,9,10,11) is located in the third RB of the physical time-frequency resource, since each candidate position corresponds to 4 CCEs, and one RB contains 4 CCEs. Therefore, for the case of L=4, the CCEs corresponding to one candidate position already occupy the entire RB, and there is no "different positions of each candidate position of PDCCH in each RB".

In another embodiment, when for different aggregation levels, the starting points of the candidate positions of PDCCH are located in the same RB, and for different RBs, the candidate positions of PDCCH are mapped to different CCE sequence number positions in different RBs:

The CCE of the mth candidate position of the PDCCH on the time-frequency resource corresponding to the search space can be determined according to the following formula:

Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer, which is a parameter used to distinguish the starting position of different users in the E-PDCCH resource, and its meaning is as described above. This will not be repeated here; i=0,...,L-1, L is the aggregation level, and N _CCE is the total number of CCEs configured for the E-PDCCH.

In order to make the method of this embodiment clearer and easier to understand, the mapping method of this embodiment will be described below by using specific examples in conjunction with the accompanying drawings.

Fig. 6 is a schematic diagram of mapping of a PDCCH search space according to an embodiment of the present invention. In this embodiment, taking M ^(RB) =4, X _k =2 as an example, according to the formula (5), the mapping result shown in FIG. 6 can be realized.

The difference from the mapping result shown in Figure 2 is that in this embodiment, for different aggregation levels, the start points of the candidate positions of PDCCH are located in the same RB, and for different RBs, the candidate positions of PDCCH are mapped to different CCE sequence number positions .

Different from the mapping result shown in FIG. 4 , in this embodiment, for different RBs, PDCCH candidate positions are mapped to different CCE sequence number positions.

Different from the mapping result shown in FIG. 5 , in this embodiment, for different aggregation levels, the start points of the candidate positions of the PDCCH are located in the same RB.

Please refer to Figure 6. When L=1, the starting point of the candidate position of PDCCH, that is, the CCE numbered 2 is mapped to the first RB of the physical time-frequency resource, and the position of each candidate position of the PDCCH in each RB Similar to FIG. 5 , description is omitted here.

Similarly, when L=2, the starting point of the candidate position of the PDCCH, that is, the CCE numbered (4,5) is also located in the first RB of the physical time-frequency resource, and each candidate position of the PDCCH is in each RB The position of is similar to that in Fig. 5, and its description is omitted here.

Similarly, when L=4, the starting point of the candidate position of the PDCCH, that is, the CCE numbered (8, 9, 10, 11) is also located in the first RB of the physical time-frequency resource.

In the above embodiments of FIG. 2-FIG. 6, for different subframes, the UE-specific parameter X _k is variable.

It can also be seen from the above embodiments that if the aggregation level is not greater than the number of control channel elements (CCEs) in each RB, that is, L≤4, then all CCEs in a candidate position of the PDCCH are mapped to the same within the RB.

According to the method of this embodiment, after each candidate position of the PDCCH is mapped to the time-frequency resource corresponding to the allocated search space, the UE should be notified of the RB configuration of the allocated search space and the sequence number of the CCE in the RB. Therefore, this The method of the embodiment may also include the following steps:

Step 103: Send the RB configuration of the search space allocated for the downlink control channel (PDCCH) and the sequence number of the CCE in the RB to the UE.

Thus, the number of times of blind detection of the UE can be reduced. In this embodiment, the sending method is not limited. For example, the RB and/or CCE sequence number of the UE may be configured through high layer signaling.

Through the method of the embodiment of the present invention, different candidate positions of the PDCCH are mapped to different RBs, and a frequency selective scheduling gain is obtained, thereby improving the transmission performance of the PDCCH.

The present invention also provides a base station, as described in the following embodiment 2, since the principle of solving the problem of the base station is similar to the mapping method of the search space of the downlink control channel in embodiment 1, so its specific implementation can refer to the embodiment The implementation of the method of 1, the similarities will not be repeated.

Example 2

An embodiment of the present invention provides a base station, which is used for mapping a search space of a downlink control channel. Figure 7 is a schematic diagram of the composition of the base station, please refer to Figure 7, the base station includes:

A determining unit 701, which determines the search space allocated for the downlink control channel (PDCCH) according to the resource allocation mode;

The mapping unit 702 is configured to map each candidate position (candidate) of the PDCCH to the time-frequency resource corresponding to the search space at intervals of resource blocks RB.

In one embodiment,

When the number M ^(RB) of RBs in the search space allocated for the PDCCH is not less than the number M ^(L) of the candidate positions, the mapping unit 702 maps each candidate position of the PDCCH to the corresponding position of the search space In different RBs of time-frequency resources.

In one embodiment,

The mapping unit 702 first maps the ^{M ( RB)} candidate positions of the PDCCH to the In different RBs of the time-frequency resources corresponding to the search space, the remaining candidate positions are mapped to different RBs of the time-frequency resources corresponding to the search space in a cyclic shift manner.

In the foregoing embodiments, for different aggregation levels, the mapping unit maps the start points of the candidate positions of the PDCCH into different RBs, or into the same RB.

In the foregoing embodiments, for different RBs, the mapping unit maps each candidate position of the PDCCH to a position of a different CCE of each RB, or to a position of the same CCE of each RB.

In one embodiment, for different aggregation levels, the mapping unit maps the starting points of the candidate positions of the PDCCH to different RBs, and for different RBs, the mapping unit maps each candidate position of the PDCCH When the position is mapped to the same CCE position of each RB, the mapping unit 702 can determine the CCE of the mth candidate position of the PDCCH on the time-frequency resource corresponding to the search space according to the following formula:

Among them, N _{CCE_RB} is the number of CCEs in an RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the total number of CCEs configured for E-PDCCH .

In one embodiment, for different aggregation levels, the mapping unit maps the starting points of the candidate positions of the PDCCH to different RBs, and for different RBs, the mapping unit maps each candidate position of the PDCCH When the position is mapped to the same CCE position of each RB, the mapping unit 702 may also determine the CCE of the mth candidate position of the PDCCH on the time-frequency resource corresponding to the search space according to the following formula:

Among them, N _{CCE_RB} is the number of CCEs in an RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the total number of CCEs configured for E-PDCCH .

In one embodiment, for different aggregation levels, the mapping unit maps the starting points of the candidate positions of the PDCCH to different RBs, and for different RBs, the mapping unit maps each candidate position of the PDCCH When the positions are mapped to different CCE positions of each RB, the mapping unit 702 may determine the CCE of the mth candidate position of the PDCCH on the time-frequency resource corresponding to the search space according to the following formula:

Among them, N _{CCE_RB} is the number of CCEs in an RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the total number of CCEs configured for E-PDCCH .

In one embodiment, for different aggregation levels, the mapping unit maps the starting points of the candidate positions of the PDCCH to the same RB, and for different RBs, the mapping unit maps each candidate position of the PDCCH When the position is mapped to the same CCE position of each RB, the mapping unit 702 can determine the CCE of the mth candidate position of the PDCCH on the time-frequency resource corresponding to the search space according to the following formula:

Among them, N _{CCE_RB} is the number of CCEs in an RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the total number of CCEs configured for E-PDCCH .

In one embodiment, for different aggregation levels, the mapping unit maps the starting points of the candidate positions of the PDCCH to the same RB, and for different RBs, the mapping unit maps each candidate position of the PDCCH When the positions are mapped to different CCE positions of each RB, the mapping unit 702 may determine the CCE of the mth candidate position of the PDCCH on the time-frequency resource corresponding to the search space according to the following formula:

Among them, N _{CCE_RB} is the number of CCEs in an RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the total number of CCEs configured for E-PDCCH .

In the foregoing embodiments, if the aggregation level is not greater than the number of control channel elements (CCEs) in each RB, all CCEs in one candidate position of the PDCCH are mapped into the same RB.

In the foregoing embodiments, for different subframes, the UE-specific parameter X _k is variable.

In one embodiment, the base station may also include:

A sending unit 703, which sends the RB configuration of the search space allocated for the downlink control channel (PDCCH) and the sequence number of the CCE in the RB to the UE.

Through the base station of this embodiment, different candidate positions of the PDCCH are mapped to corresponding RBs, so that a frequency selective scheduling gain can be obtained, thereby improving the transmission performance of the PDCCH.

An embodiment of the present invention also provides a computer-readable program, wherein, when the program is executed in the base station, the program causes the computer to execute the method for mapping the search space of the downlink control channel described in Embodiment 1 in the base station .

An embodiment of the present invention also provides a storage medium storing a computer-readable program, wherein the computer-readable program enables a computer to execute the method for mapping a search space of a downlink control channel described in Embodiment 1 in a base station.

The above devices and methods of the present invention can be implemented by hardware, or by combining hardware and software. The present invention relates to such a computer-readable program that, when the program is executed by a logic component, enables the logic component to realize the above-mentioned device or constituent component, or enables the logic component to realize the above-mentioned various methods or steps. Logic components such as field programmable logic components, microprocessors, processors used in computers, and the like. The present invention also relates to a storage medium for storing the above program, such as hard disk, magnetic disk, optical disk, DVD, flash memory and the like.

The present invention has been described above in conjunction with specific embodiments, but those skilled in the art should be clear that these descriptions are all exemplary and not limiting the protection scope of the present invention. Those skilled in the art can make various variations and modifications to the present invention according to the spirit and principle of the present invention, and these variations and modifications are also within the scope of the present invention.

Claims (23)

1. A method for mapping a search space of a downlink control channel, wherein the method comprises: determining the search space allocated for the downlink control channel according to the resource allocation method; Mapping each candidate position candidate of the downlink control channel to the time-frequency resource corresponding to the search space at intervals of resource blocks RB; Wherein, if the number M ^(RB) of RBs in the search space allocated for the downlink control channel is not less than the number M ^(L) of the candidate positions, each candidate position of the downlink control channel is mapped to the search space Spaces correspond to different RBs of time-frequency resources. 2. A method for mapping a search space of a downlink control channel, wherein the method comprises: determining the search space allocated for the downlink control channel according to the resource allocation method; Mapping each candidate position candidate of the downlink control channel to the time-frequency resource corresponding to the search space at intervals of resource blocks RB; Wherein, if the number M ^(RB) of RBs in the search space allocated for the downlink control channel is less than the number M ^(L) of the candidate positions, first map the M ^(RB) candidate positions of the downlink control channel into different RBs of the time-frequency resources corresponding to the search space, and then map the remaining candidate positions to different RBs of the time-frequency resources corresponding to the search space in a cyclic shift manner. 3. The method according to claim 1 or 2, wherein, For different aggregation levels, the starting points of the candidate positions of the downlink control channel are located in different RBs. 4. The method according to claim 3, wherein, for each candidate position of the downlink control channel mapped to different RBs, the positions of the CCEs on the different RBs are the same or different. 5. The method according to claim 4, wherein, when mapping to each candidate position of the downlink control channel in different RBs, when the positions of the CCEs on the different RBs are the same, the following formula is used to determine the The CCE of the mth candidate position of the downlink control channel on the time-frequency resource corresponding to the search space: Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the number of CCEs configured for the enhanced downlink control channel Total number; m'=m in the absence of carrier aggregation CA, m'=m+M ^(L) n _CI in the presence of carrier aggregation CA, where n _CI is the value of the carrier indicator field value, M ^(L) is the number of candidate positions of the PDCCH. 6. The method according to claim 4, wherein, when mapping to each candidate position of the downlink control channel in different RBs, the positions of the CCEs on the different RBs are the same, the following formula is used to determine the The CCE of the mth candidate position of the downlink control channel on the time-frequency resource corresponding to the search space: Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the number of CCEs configured for the enhanced downlink control channel Total number; m'=m in the absence of carrier aggregation CA, m'=m+M ^(L) n _CI in the presence of carrier aggregation CA, where n _CI is the value of the carrier indicator field value, M ^(L) is the number of candidate positions of the PDCCH. 7. The method according to claim 4, wherein, when mapping to each candidate position of the downlink control channel in different RBs, and the positions of the CCEs on the different RBs are different, the The CCE of the mth candidate position of the downlink control channel on the time-frequency resource corresponding to the search space: Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the number of CCEs configured for the enhanced downlink control channel Total number; m'=m in the absence of carrier aggregation CA, m'=m+M ^(L) n _CI in the presence of carrier aggregation CA, where n _CI is the value of the carrier indicator field value, M ^(L) is the number of candidate positions of the PDCCH. 8. The method of claim 1 or 2, wherein, For different aggregation levels, the starting points of the candidate positions of the downlink control channels are located in the same RB. 9. The method according to claim 8, wherein, for each candidate position of the downlink control channel mapped to different RBs, the positions of the CCEs on the different RBs are the same or different. 10. The method according to claim 9, wherein, when mapping to each candidate position of the downlink control channel in different RBs, the positions of the CCEs on the different RBs are the same, the following formula is used to determine the The CCE of the mth candidate position of the downlink control channel on the time-frequency resource corresponding to the search space: Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the number of CCEs configured for the enhanced downlink control channel Total number; m'=m in the absence of carrier aggregation CA, m'=m+M ^(L) n _CI in the presence of carrier aggregation CA, where n _CI is the value of the carrier indicator field value, M ^(L) is the number of candidate positions of the PDCCH. 11. The method according to claim 9, wherein, when mapping to each candidate position of the downlink control channel in different RBs, the positions of the CCEs on the different RBs are different, the following formula is used to determine the The CCE of the mth candidate position of the downlink control channel on the time-frequency resource corresponding to the search space: Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the number of CCEs configured for the enhanced downlink control channel Total number; m'=m in the absence of carrier aggregation CA, m'=m+M ^(L) n _CI in the presence of carrier aggregation CA, where n _CI is the value of the carrier indicator field value, M ^(L) is the number of candidate positions of the PDCCH. 12. The method of claim 5 or 6 or 7 or 10 or 11, wherein, For different subframes, the UE-specific parameter X _k is variable. 13. A base station, which is used for mapping a search space of a downlink control channel, wherein the base station comprises: A determining unit, which determines the search space allocated for the downlink control channel according to the resource allocation mode; a mapping unit, which maps each candidate position candidate of the downlink control channel to the time-frequency resource corresponding to the search space at intervals of resource blocks RB; ^{Wherein ,} the mapping unit maps each candidate position of the downlink control channel to to different RBs of the time-frequency resource corresponding to the search space. 14. A base station, which is used for mapping a search space of a downlink control channel, wherein the base station comprises: A determining unit, which determines the search space allocated for the downlink control channel according to the resource allocation mode; a mapping unit, which maps each candidate position candidate of the downlink control channel to the time-frequency resource corresponding to the search space at intervals of resource blocks RB; Wherein, when the number M ^(RB) of RBs in the search space allocated for the downlink control channel is less than the number M ^(L) of the candidate positions, the mapping unit first maps the number M ( ^RB ) of the downlink control channel to The candidate positions are mapped to different RBs of the time-frequency resources corresponding to the search space, and then the remaining candidate positions are mapped to different RBs of the time-frequency resources corresponding to the search space in a cyclic shift manner. 15. The base station according to claim 13 or 14, wherein, For different aggregation levels, the mapping unit maps the starting points of the candidate positions of the downlink control channel into different RBs. 16. The base station according to claim 15, wherein, for each candidate position of the downlink control channel mapped to different RBs, the positions of the CCEs on the different RBs are the same or different. 17. The base station according to claim 16, wherein, when mapping to each candidate position of the downlink control channel in different RBs, the positions of the CCEs on the different RBs are the same, the mapping unit according to the following The formula determines the CCE of the mth candidate position of the downlink control channel on the time-frequency resource corresponding to the search space: Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the number of CCEs configured for the enhanced downlink control channel Total number; m'=m in the absence of carrier aggregation CA, m'=m+M ^(L) n _CI in the presence of carrier aggregation CA, where n _CI is the value of the carrier indicator field value, M ^(L) is the number of candidate positions of the PDCCH. 18. The base station according to claim 16, wherein, when mapping to each candidate position of the downlink control channel in different RBs, the positions of the CCEs on the different RBs are the same, the mapping unit according to the following The formula determines the CCE of the mth candidate position of the downlink control channel on the time-frequency resource corresponding to the search space: Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the number of CCEs configured for the enhanced downlink control channel Total number; m'=m in the absence of carrier aggregation CA, m'=m+M ^(L) n _CI in the presence of carrier aggregation CA, where n _CI is the value of the carrier indicator field value, M ^(L) is the number of candidate positions of the PDCCH. 19. The base station according to claim 16, wherein, when mapping to each candidate position of the downlink control channel in different RBs, the positions of the CCEs on the different RBs are different, the mapping unit according to the following The formula determines the CCE of the mth candidate position of the downlink control channel on the time-frequency resource corresponding to the search space: Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the number of CCEs configured for the enhanced downlink control channel Total number; m'=m in the absence of carrier aggregation CA, m'=m+M ^(L) n _CI in the presence of carrier aggregation CA, where n _CI is the value of the carrier indicator field value, M ^(L) is the number of candidate positions of the PDCCH. 20. The base station according to claim 13 or 14, wherein, For different aggregation levels, the mapping unit maps the starting points of the candidate positions of the downlink control channel into the same RB. 21. The base station according to claim 20, wherein, for each candidate position of the downlink control channel mapped to different RBs, the positions of the CCEs on the different RBs are the same or different. 22. The base station according to claim 21, wherein, when mapping to each candidate position of the downlink control channel in different RBs, the positions of the CCEs on the different RBs are the same, the mapping unit according to the following The formula determines the CCE of the mth candidate position of the downlink control channel on the time-frequency resource corresponding to the search space: Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the number of CCEs configured for the enhanced downlink control channel Total number; m'=m in the absence of carrier aggregation CA, m'=m+M ^(L) n _CI in the presence of carrier aggregation CA, where n _CI is the value of the carrier indicator field value, M ^(L) is the number of candidate positions of the PDCCH. 23. The base station according to claim 20, wherein, when mapping to each candidate position of the downlink control channel in different RBs, the positions of the CCEs on the different RBs are different, the mapping unit according to the following The formula determines the CCE of the mth candidate position of the downlink control channel on the time-frequency resource corresponding to the search space: Among them, N _{CCE_RB} is the number of CCEs in one RB; X _k is a UE-specific parameter configured by the upper layer; i=0,...,L-1, L is the aggregation level, and N _CCE is the number of CCEs configured for the enhanced downlink control channel Total number; m'=m in the absence of carrier aggregation CA, m'=m+M ^(L) n _CI in the presence of carrier aggregation CA, where n _CI is the value of the carrier indicator field value, M ^(L) is the number of candidate positions of the PDCCH.