CN102905370B

CN102905370B - A kind of method and system for realizing control channel resource distribution

Info

Publication number: CN102905370B
Application number: CN201110210999.9A
Authority: CN
Inventors: 郑勇; 孙云锋; 郭森宝; 任敏; 弓宇宏
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2011-07-26
Filing date: 2011-07-26
Publication date: 2017-08-11
Anticipated expiration: 2031-07-26
Also published as: CN102905370A

Abstract

The invention discloses a kind of method and system for realizing control channel resource distribution, when can not have the UE for dispatching R8/R9/R10 in ABS, the control channel Jing Guo precoding is mapped since first OFDM symbol of the ABS.The present invention realizes the technology of control channel resource distribution, the optimization that can apply to the control channel resource distribution of LTER10 later releases and indicate.By making full use of the RE of non-carrying information in ABS, improve the level of resources utilization and improve control channel covering power, UE is saved and reduced to UE all has beneficial effect to the blind check complexity of above-mentioned control channel.

Description

Method and system for realizing control channel resource allocation

Technical Field

The present invention relates to the field of communications, and in particular, to a method and system for implementing resource allocation of a control channel.

Background

In order to increase the capacity of the cellular network, a Low Power Node (LPN) is introduced under the coverage of a Macro cell (Macro cell) to form a plurality of micro cells. Network system throughput is increased by providing access to these micro cells by User Equipments (UEs) within range of the macro cell. When these micro cells are assigned independent cell IDs, the micro cells correspond to an independent cell. In order to access as many users as possible to the micro cell, thereby reducing the load of the macro cell and realizing reuse of time-frequency resources, when the UE performs handover between the macro cell and the LPN cell, an offset relative to the received power of the macro cell is usually added to the received signal power of the LPN cell, so that the UE can preferentially access the LPN cell in the process of comparing the received powers of the two cells to determine an access cell. In this case, the power of signals received from the LPN by the UEs of some LPN cells may be smaller than the power of the received Macro base station (Macro eNB, MeNB), and thus may be interfered by the Macro cell, and these UEs are referred to as edge UEs of the LPN cell.

In order to reduce interference to LPN cell edge UEs, in LTE Release (R) 10, a macro cell is usually configured with a certain number of null subframes (ABS) periodically, and in ABS, an MeNB may transmit data by non-transmission or low power to reduce interference to LPN cell edge UEs. After the LPN cell and the macro cell achieve subframe synchronization, the edge UE of the LPN cell can receive data in the subframes of the LPN cells protected by the macro cell ABS without being seriously interfered by the macro cell. In addition, the original Common reference signal (Common reference signal), broadcast channel (PBCH), primary synchronization/secondary synchronization signal (PSS/SSS) still need to be maintained in ABS, and if 0/4/5/9 subframe of FDD (frequency division duplex) system or 0/1/5/6 subframe of TDD (time division duplex) system is configured as ABS by macro cell, some Common Information may exist in Physical Downlink Shared Channel (PDSCH) and Physical Downlink Control Channel (PDCCH) of these ABS, such as call (paging), System Information Block (SIB), Random Access Channel (RACH), and Downlink Control Information (DCI) corresponding to these Common Information, respectively.

In order to further avoid interference in heterogeneous networks and increase the control channel capacity, in a study of a later release of LTE R10, an enhanced control channel (E-PDCCH) design similar to a Relay control channel (Relay PDCCH, R-PDCCH) was proposed. The R-PDCCH is a set of Resource Blocks (RBs) configured by the base station in a semi-static manner, and is usually located on a PDSCH Resource of a first slot of a subframe, and a Control Channel Element (CCE) of the R-PDCCH may be an RB on the PDSCH. The R-PDCCH is characterized by using a UE-specific Reference Signal (URS). The URS is characterized in that it transmits only on the used resources and performs precoding processing of the spatial domain, so that it is possible to directly demodulate the corresponding data through the URS without knowing the used precoding. This allows the control channel to also use precoding for transmit beamforming to avoid interference to certain UEs, as with the data channel resources. The starting position of the control channel is behind the PDCCH in a normal subframe without ABS, so that the interference on the PDCCH of the UE of R8/R9/R10 can be avoided, and the interference on the PDSCH of other UE can be avoided through beam adjustment.

In ABS, the UEs of R8/R9/R10 may be scheduled at low power. The low power scheduling is limited by the distance of the MeNB from the nearest LPN edge UE, so the number of UEs of R8/R9/R10 that can be scheduled is limited. To improve the resource utilization of the ABS, it may be considered to schedule only UEs having a URS-based control channel in all or part of the ABS. Current R-PDCCH designs only allow for transmission in normal subframes, i.e., the time domain starting position in a subframe is the first Orthogonal Frequency Division Multiplexing (OFDM) symbol after the PDCCH. However, for the ABSs of the UEs not scheduled with R8/9/10, if the control channel is mapped from the OFDM symbol following the PDCCH, the user information is not transmitted in the PDCCH of the ABSs of the UEs not scheduled with R8/9/10, and thus most of the transmission resources are wasted.

Disclosure of Invention

In view of the above, the present invention provides a method and a system for implementing resource allocation of a control channel, so as to improve resource utilization efficiency.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a method of implementing control channel resource allocation, the method comprising:

in the absence of a user equipment UE of scheduling version R8/R9/R10 in the null subframe ABS, the precoded control channel is mapped starting from the first orthogonal frequency division multiplexing, OFDM, symbol of the ABS.

The method further comprises the following steps: and indicating the starting position of the control channel mapping of the UE.

The method for indicating the starting position comprises the following steps:

the base station side informs the UE of the ABS configuration mode through a Radio Resource Control (RRC) signaling mode; or,

the base station side informs the UE of the position of the initial OFDM symbol mapped by the E-PDCCH of the enhanced control channel in a mode of indicating a physical control format indicator channel PCFICH.

When a base station side informs UE of an ABS configuration mode of the UE in an RRC signaling mode, the content informed by the RRC signaling is a bitmap of the ABS in a configuration period or a predefined configuration mode index number;

when the base station side informs the UE of the initial OFDM symbol position mapped by the E-PDCCH in a PCFICH indicating mode, the CFI code word sequence is indicated by using a control format reserved in an LTE R10 protocol to configure indicating information that the number of OFDM symbols occupied by the PDCCH is 0.

The method further comprises the following steps:

when the public information is sent in the ABS, indicating the number of OFDM symbols occupied by the PDCCH by using the PCFICH of the ABS which sends the public information; at this time, whether the configuration information of the ABS is sent to the UE through RRC signaling or not, mapping the E-PDCCH from an OFDM symbol behind an OFDM symbol region occupied by the PDCCH indicated by the PCFICH; or,

when the public information is sent in the ABS, indicating the number of OFDM symbols occupied by the PDCCH by using the PCFICH of the ABS which sends the public information; after configuration information of the ABS is sent to the UE through RRC signaling, the E-PDCCH starts mapping from the first OFDM of the ABS, the number of OFDM symbols occupied by the PDCCH is indicated by the PCFICH and is not 0; in the mapping process, for the ABS which is likely to send the common information, the common search space of the PDCCH region is assumed to be configured according to the maximum configurable number of control channel elements CCE, and the resource element group REG occupied after interleaving and mapping is avoided; and, rate matching is performed on REs of the E-PDCCH near these REGs.

The method further comprises the following steps: the UE blindly detects the E-PDCCH; in the blind detection process, for the ABS which is likely to send the public information, the UE assumes that the public search space is configured according to the maximum configurable CCE number, avoids the positions of the REGs occupied by the REGs after interleaving and mapping, performs rate matching, and then performs blind detection on the E-PDCCH special for the UE.

Starting mapping of the E-PDCCH only from a symbol after the PDCCH with the largest possible symbol number, regardless of whether the PDCCH has UE-specific DCI;

and the PDSCH corresponding to the E-PDCCH and the E-PDCCH have the same OFDM initial symbol position.

A system for realizing control channel resource allocation comprises a UE scheduling decision unit and a mapping unit; wherein,

the UE scheduling decision unit is used for confirming that no UE with R8/R9/R10 is scheduled in the ABS;

the mapping unit is configured to map the precoded control channel from the first OFDM symbol of the ABS when the UE scheduling decision unit determines that no UE is scheduled with R8/R9/R10 in the ABS.

The mapping unit is further configured to: and indicating the starting position of the control channel mapping of the UE.

The mapping unit, when indicating the start position, is configured to:

informing the UE of the ABS configuration mode in an RRC signaling mode; or,

and informing the UE of the position of the starting OFDM symbol mapped by the E-PDCCH in a mode of PCFICH indication.

When the UE is informed of the ABS configuration mode through an RRC signaling mode, the content informed by the RRC signaling is a bitmap of the ABS in a configuration period or a predefined configuration mode index number;

when the UE is informed of the starting OFDM symbol position mapped by the E-PDCCH in the PCFICH indication manner, the mapping unit is configured to: and configuring indication information of 0 number of OFDM symbols occupied by the PDCCH by using a CFI codeword sequence reserved in the LTE R10 protocol.

When the common information is sent in the ABS, the mapping unit is configured to: indicating the number of OFDM symbols occupied by PDCCH by using PCFICH of ABS which sends public information; at this time, whether the configuration information of the ABS is sent to the UE through RRC signaling or not, mapping the E-PDCCH from an OFDM symbol behind an OFDM symbol region occupied by the PDCCH indicated by the PCFICH; or,

when the common information is sent in the ABS, the mapping unit is configured to: indicating the number of OFDM symbols occupied by PDCCH by using PCFICH of ABS which sends public information; after configuration information of the ABS is sent to the UE through RRC signaling, the E-PDCCH starts mapping from the first OFDM of the ABS, the number of OFDM symbols occupied by the PDCCH is indicated by the PCFICH and is not 0; in the mapping process, for the ABS which is likely to send the public information, the public information is mapped firstly, then the E-PDCCH information is mapped, and the REG occupied by the public information after the REG interweaving and mapping is avoided when the E-PDCCH is mapped; and, rate matching is performed on REs of the E-PDCCH near these REGs.

The UE is configured to: blind detection of the E-PDCCH; in the blind detection process, for the ABS which is likely to send the public information, the public information is firstly detected in a blind manner, after the REG mapping positions are detected and obtained, the positions are avoided and rate matching is carried out, and then the E-PDCCH special for the UE is detected in a blind manner.

The mapping unit is configured to:

The method and the device for realizing the control channel resource allocation can be applied to the optimization of the control channel resource allocation and indication of the subsequent version of LTE R10. By fully utilizing the RE which does not bear information in the ABS, the resource utilization efficiency is improved, the control channel coverage capability is improved, and the method has the advantages of saving energy for the UE and reducing the blind detection complexity of the UE on the control channel.

Drawings

FIG. 1 is a schematic view of a macro + pico scene according to an embodiment of the present invention;

FIG. 2 is a diagram illustrating an E-PDCCH start symbol position according to an embodiment of the present invention;

FIG. 3 is a flowchart illustrating an E-PDCCH initial position indication according to an embodiment of the present invention;

FIG. 4 is a flowchart of indicating the starting position of the E-PDCCH through a Physical Control Format Indicator Channel (PCFICH) according to an embodiment of the present invention;

FIG. 5 is a flowchart of indicating the starting position of the E-PDCCH by notifying the ABS configuration according to the embodiment of the present invention;

FIG. 6 is a simplified flowchart of an embodiment of the present invention for implementing resource allocation of a control channel;

fig. 7 is a system diagram for implementing resource allocation of a control channel according to an embodiment of the present invention.

Detailed Description

In practical applications, the precoded control channel may be mapped starting from the first OFDM symbol of the ABS, in case there are no UEs scheduling R8/R9/R10 in the ABS. In order to enable the UE to know that the mapping of its control channel resources is from the first OFDM symbol, the base station side can indicate the starting position of the UE control channel mapping in two ways. One way is via PCFICH indication, and the other way is via Radio Resource Control (RRC) signaling (including unicast RRC signaling or system message SIB). When the UE detects the indication of mapping from the first OFDM symbol, the UE performs control channel detection from the first OFDM symbol of the indicated ABS.

It should be noted that, when the base station side notifies the UE of its ABS configuration mode through an RRC signaling mode, the content notified by the RRC signaling may be a bitmap (bitmap) of the ABS in a configuration period or an index number of a predefined configuration mode. After knowing the ABS configuration information, the UE can accordingly determine which subframes on the E-PDCCH are mapped from the first OFDM symbol.

When the base station side notifies the UE of the initial OFDM symbol position mapped by the E-PDCCH in a mode of PCFICH indication, indication information with the OFDM symbol number of the PDCCH being 0 can be configured by using a reserved Control Format Indicator (CFI) codeword sequence, so that the UE with the capability of identifying the information can judge that the E-PDCCH is mapped from the first OFDM symbol in the current subframe.

When the common information is transmitted in the ABS, the PCFICH of the ABS transmitting the common information may be used to indicate the number of OFDM symbols occupied by the PDCCH. At this time, whether the configuration information of the ABS is transmitted to the UE through RRC signaling or not, the E-PDCCH is mapped from an OFDM symbol after an OFDM symbol region occupied by the PDCCH indicated by the PCFICH. The common information may be paging (paging), SIB, RACH, etc.

In addition, when the common information is transmitted in the ABS, the PCFICH of the ABS transmitting the common information may indicate the number of OFDM symbols occupied by the PDCCH. After configuration information of the ABS is sent to the UE through RRC signaling, the E-PDCCH starts mapping from the first OFDM of the ABS, wherein the PCFICH indicates that the number of OFDM symbols occupied by the PDCCH is not 0. In the mapping process, it is assumed that a common search space of a PDCCH region is configured according to the maximum configurable number of Control Channel Elements (CCEs) (from the 1 st CCE to the 8 th CCE in the search space in LTE R8/9/10), and REGs occupied after interleaving and mapping by Resource Element Groups (REGs) are avoided. And, rate matching is performed on REs of the E-PDCCH near these REGs. In the ABS in which the PCFICH indicates that the number of OFDM symbols occupied by the PDCCH is not 0, another method for mapping the E-PDCCH from the first OFDM symbol is to map the common information first and then map the E-PDCCH. In this process, mapping of the E-PDCCH avoids the REGs occupied by the common information and performs rate matching. The second method does not require an assumption on the number of CCEs occupied by the common information.

In the process of blind detection of the E-PDCCH, the UE may assume that the common search space in the PDCCH region is configured according to the maximum configurable CCE number, and avoid the REG occupied after resource interleaving and mapping. And, REs of the E-PDCCH near these REGs are rate-matched and then blind-checked. When blind detection is performed, the UE may perform blind detection on the common information, avoid the REG mapping positions after the REG mapping positions are detected and acquired, perform rate matching, and perform blind detection on the E-PDCCH specific to the UE.

In practical applications, it can also be defined that E-PDCCH can only be mapped starting from the symbol after the PDCCH with the largest possible number of symbols, regardless of whether the PDCCH has UE-specific DCI.

Based on the mapping of the E-PDCCH, the PDSCH corresponding to the E-PDCCH and the E-PDCCH have the same OFDM initial symbol position.

The invention is described below with reference to the drawings and examples.

A macro + pico configuration as shown in fig. 1 may be considered. In fig. 1, pico cells are distributed within the coverage area of a macro cell. In order to ensure that the UE at the edge of the pico cell can normally communicate, the macro configures some ABS, and in the configured ABS subframes, the MeNB can schedule the UE of R8/R9/R10/R11 at low power or only schedule the UE of R11 and avoid the interference to the pico edge UE through beam cooperation. In ABS, if no UE of R8/R9/R10 is scheduled, the E-PDCCH and PDSCH of the UE of R11 can be mapped starting from the first symbol of the ABS subframe satisfying this condition in order to fully utilize resources.

Example 1:

as shown in fig. 3, the UE not scheduling R8/R9/R10 in the ABS configured in the embodiment of the present invention indicates whether the UE performs blind detection from the first OFDM symbol in an RRC signaling manner.

In this case, the procedures of E-PDCCH resource allocation and user detection are as follows:

the MeNB sends ABS configuration information to the UE of R11. The ABS configuration may be a 40-bit bitmap, where each bit corresponds to one subframe, and 40 bits correspond to 40 subframes, as shown in fig. 3, 1 may be used to represent ABS and 0 may be used to represent non-ABS, that is, the bitmap of ABS in the figure may be configured as:

[0 0 0 0 1 1 0 0 0 1 0 0 0 1 1 0 0 0 0 1 0 0 0 0 1 1 0 0 0 1 0 0 0 01 0 0 0 0 1]。

the bitmap may be several pre-configured patterns, each pattern is represented by an index number, and the index number is notified, so that the UE knows the ABS in the 40 subframes, where each bit represents one subframe. The 40 subframes are contained in 4 radio frames, of which the first radio frame number n_fSatisfies mod (n)_f,4)＝0。

The example implementation may be described as:

step 301: judging that the current subframe is ABS;

step 302: judging whether the subframe number of the current ABS is 0, 4, 5, 9 (the PDCCH may contain common information), if so, entering step 305; otherwise, step 303 is entered.

Step 303: and the base station side maps the E-PDCCH from the first OFDM symbol.

Step 304: the UE starts to blindly detect the E-PDCCH from the first OFDM symbol and ends the process.

Step 305: the base station side configures CFI according to the number of symbols occupied by the public information in the PDCCH, and maps the E-PDCCH from the symbol indicated by the CFI.

Step 306: the UE side detects the CFI value in the PCFICH and blindly detects the E-PDCCH from the OFDM symbol after the number of the OFDM symbols indicated by the CFI.

Example 2:

unlike embodiment 1, in this embodiment, whether mapping of E-PDCCH starts from 1 st OFDM symbol of the current subframe is indicated by configuring the number of PDCCH occupied symbols indicated by CFI to be 0. As shown in fig. 4, in the embodiment of the present invention, the starting symbol positions of the E-PDCCH and the corresponding PDSCH are indicated by the PCFICH. The CFI indication as shown in table 1 is configured in the existing 3GPP protocol 36.212:

TABLE 1 PDCCH symbol number indicated by CFI and codeword correspondence thereof

The all-zero sequence codeword configured to be 4 by the CFI reserved in table 1 may be utilized to indicate that the current E-PDCCH is mapped from the first OFDM symbol of the current subframe, i.e., the number of OFDM symbols occupied by the PDCCH is 0.

step 401: the current subframe is ABS;

step 402: judging whether the current subframe number is 0, 4, 5 or 9, if so, entering step 403; otherwise, go to step 405;

step 403: the base station side configures CFI to indicate the number of PDCCH symbols, and maps the E-PDCCH from the symbol after the PDCCH of the current subframe, as shown in b in FIG. 2;

step 404: the UE detects the PCFICH, acquires the number of symbols occupied by the PDCCH through the detected CFI, and starts to blindly detect the E-PDCCH from the symbols behind the PDCCH to finish the process;

step 405: a base station configures a code word with a CFI indicating that the PDCCH occupies 0 OFDM symbols, and maps the E-PDCCH from the first OFDM symbol of the current subframe, as shown in c in figure 2;

step 406: and the UE detects the PCFICH, and when the number of the OFDM symbols of the PDCCH is known to be 0 by detecting the CFI, the E-PDCCH is detected in a blind mode from the first OFDM symbol of the current subframe.

Example 3:

unlike embodiment 2, in this embodiment, it is not indicated by CFI whether to map E-PDCCH from the first OFDM symbol of the current ABS subframe, but the UE is informed by RRC signaling which subframes are ABS at which time in the form of ABS bitmap. Unlike embodiment 1, in the present embodiment, the E-PDCCH is not mapped from the OFDM symbol following the PDCCH in the 0, 4, 5, 9 subframes, but always from the first OFDM symbol. As shown in FIG. 5, in the embodiment of the present invention, the MeNB does not schedule the R8/9/10 UE in the ABS. In ABS, the E-PDCCH and PDSCH of the UE of R11 are always mapped starting from the first OFDM symbol. At this time, the UE of R11 needs to be informed of the ABS configuration condition through RRC signaling, so that the UE knows the mapped subframe from the first symbol.

step 501: judging that the current subframe is ABS;

step 502: judging whether the current subframe number is 0, 4, 5 or 9, if so, entering step 503; otherwise, go to step 506;

step 503: the base station side configures the number of PDCCH symbols indicated by CFI as the possible maximum value, and maps the E-PDCCH from the first OFDM symbol of the current subframe, as shown in a in FIG. 2;

step 504: the MeNB assumes that the search space of the PDCCH is configured to be the largest in mapping the E-PDCCH, i.e., the common search space occupies the 1 st to 8 th CCEs of the search space. After the REGs corresponding to the CCEs are interleaved and mapped, the E-PDCCH avoids the REGs in the mapping process and performs rate matching.

Step 505: the UE assumes the common search space in the PDCCH to be the 1 st to 8 th CCEs and can determine the interleaved REG locations accordingly. In the process of blind detection of the E-PDCCH, when there is REG corresponding to the PDCCH common channel in a Physical Resource Block (PRB), the UE defaults that there is no required information in these REGs, and performs rate matching and blind detection in a predefined manner, as shown in a in fig. 2. The flow is ended.

Step 506: if the current ABS subframe number is not 0, 4, 5, 9, the base station side maps the E-PDCCH from the 1 st OFDM symbol of the current subframe, the mapping mode is as shown in c in fig. 2.

Step 507: and when the UE performs E-PDCCH blind detection, the default E-PDCCH is mapped from the first OFDM symbol.

As can be seen from the above description, the operation idea of the present invention for implementing resource allocation of control channel can be represented by a flow shown in fig. 6, where the flow includes the following steps:

step 610: confirming that there are no UEs scheduling R8/R9/R10 in the ABS.

Step 620: mapping the precoded control channel starting from the first OFDM symbol of the ABS.

In order to ensure that the technical description and the operation idea can be smoothly realized, the arrangement shown in fig. 7 can be performed. Referring to fig. 7, fig. 7 is a system diagram for implementing resource allocation of a control channel according to an embodiment of the present invention, where the system includes a UE scheduling decision unit and a mapping unit connected to each other.

In practical application, the UE scheduling decision unit can confirm that no UE scheduling R8/R9/R10 exists in the ABS. The mapping unit can map the precoded control channel from the first OFDM symbol of the ABS when the UE scheduling decision unit confirms that no UE is scheduled with R8/R9/R10 in the ABS.

In summary, the technology for implementing the control channel resource allocation can be applied to the optimization of the control channel resource allocation and indication of the subsequent release of LTE R10, regardless of the method or the system. By fully utilizing the RE which does not bear information in the ABS, the resource utilization efficiency is improved, the control channel coverage capability is improved, and the method has the advantages of saving energy for the UE and reducing the blind detection complexity of the UE on the control channel.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.

Claims

1. A method for implementing control channel resource allocation, the method comprising:

2. The method of claim 1, further comprising: and indicating the starting position of the control channel mapping of the UE.

3. The method of claim 2, wherein the method of indicating the starting position is:

4. The method of claim 3,

when the base station side informs the UE of the initial OFDM symbol position mapped by the E-PDCCH in a mode of PCFICH indication, the CFI code word sequence is indicated by using a control format reserved in an LTER10 protocol to configure indication information with the number of OFDM symbols occupied by a physical downlink control channel PDCCH being 0.

5. The method of any one of claims 1 to 4, further comprising:

6. The method of claim 5, further comprising: the UE blindly detects the E-PDCCH; in the blind detection process, for the ABS which is likely to send the public information, the UE assumes that the public search space is configured according to the maximum configurable CCE number, avoids the positions of the REGs occupied by the REGs after interleaving and mapping, performs rate matching, and then performs blind detection on the E-PDCCH special for the UE.

7. The method according to any one of claims 1 to 4,

8. A system for realizing control channel resource allocation is characterized in that the system comprises a UE scheduling decision unit and a mapping unit; wherein,

9. The system of claim 8, wherein the mapping unit is further configured to: and indicating the starting position of the control channel mapping of the UE.

10. The system of claim 9, wherein the mapping unit, when indicating the starting location, is configured to:

informing the UE of the ABS configuration mode in an RRC signaling mode; or,

11. The system of claim 10,

12. The system according to any one of claims 8 to 11,

13. The system of claim 12, wherein the UE is configured to: blind detection of the E-PDCCH; in the blind detection process, for the ABS which is likely to send the public information, the public information is firstly detected in a blind manner, after the REG mapping positions are detected and obtained, the positions are avoided and rate matching is carried out, and then the E-PDCCH special for the UE is detected in a blind manner.

14. The system according to any one of claims 8 to 11, wherein the mapping unit is configured to: