CN103874202A

CN103874202A - Method for space searching in enhanced control channel

Info

Publication number: CN103874202A
Application number: CN201210525923.XA
Authority: CN
Inventors: 焦慧颖
Original assignee: Research Institute of Telecommunications Transmission Ministry of Industry and Information Technology
Current assignee: Spreadtrum Communications Shanghai Co Ltd; Research Institute of Telecommunications Transmission Ministry of Industry and Information Technology
Priority date: 2012-12-07
Filing date: 2012-12-07
Publication date: 2014-06-18
Anticipated expiration: 2032-12-07
Also published as: CN103874202B

Abstract

Disclosed is a method for space searching in an enhanced control channel. An enhanced downlink control channel is composed of three ePDCCH groups. The method comprises the following steps: step 1, a base station performs configuration to enable each terminal to monitor two ePDCCH groups including a main ePDCCH group and an auxiliary ePDCCH group, and terminals in different groups is configured with the same main ePDCCH group and different auxiliary ePDCCH groups; and step 2, the terminals search a common search space in the main ePDCCH group to obtain common downlink control information. A new common search space and special search spaces for the terminals are designed to enable the number of times of blind decoding by the terminals to be kept unchanged.

Description

A kind of method that strengthens search volume in control channel

Technical field

The present invention relates to wireless communication field, and be particularly related to a kind of method that strengthens search volume in control channel.

Background technology

The LTE network design initial stage, most one or two transmitting antennas of base station deployment, along with the increase of load, operator increases number of antennas by consideration and improves spectrum efficiency, and popularizing along with LTE, more base station will be deployed to suburb or even grass roots, increasing on the basis of antenna amount, also will consider coverage.

Base station deployment multi-antenna array, downlink data can obtain the gain of wave beam forming, and down control channel (PDCCH) is owing to adopting the mode of transmit diversity, can not well obtain the gain that number of antennas increase brings, therefore consider that introducing the precoding mode identical with data channel designs control channel, this namely introduces the reason that strengthens down control channel (ePDCCH).

Strengthen down control channel and be positioned at data area, descending demodulation pilot frequency (DM RS) will be available for demodulation, some pilot tones are in addition (as CRS, CSI-RS) and the existence of down control channel affected the upper available RE number of a RB, for the descending covering that strengthens down control channel is not affected, the RE maximum number of an ePDCCH support must be more than or equal to the RE number (288) in PDCCH polymerization grade maximum (8) situation, therefore considers the situation of supporting that higher polymerization grade is 16.

At present, the down control channel of LTE R8 is organized with the form of CCE, and 1 CCE is made up of 4 RE 9 REG(1 REG) form, define 4 kinds of PDCCH forms, take respectively 1,2,4 and 8 CCE, be called polymerization grade.Terminal receives the mode that adopts blind Detecting to PDCCH, search volume is divided into public search space and terminal-specific search volume.

The down control channel of LTE R8 has defined two public search spaces, and polymerization grade is respectively 4 and 8, and the size in space is 16 CCE, due to need to the decode DCI of two kinds of different length types of terminal, and need to maximum 12 blind checks in public search space.

For each UE, 4 spaces that UE is special are defined again, polymerization grade is respectively 1,2,4 and 8, corresponding space size is 6,12,8 and 16 CCE, when upstream data is single codeword transmission, the terminal two kinds of dissimilar DCI that need to attempt decoding, need to be terminal-specific search volume search 32 times.

The backward position number of terminal-specific search volume and public search space is as shown in the table.

Table 1-terminal-specific search volume

Polymerization grade	PDCCH candidate collection
		1	6
2	6
		4	2
8	2

Table 2-public search space

Polymerization grade	PDCCH candidate collection
		4	4
8	2

If increasing polymerization grade in enhancing down control channel is 16, corresponding search volume will redesign, and simultaneously in order not increase the complexity of terminal, requires searching times to remain unchanged.

Therefore,, when design strengthens down control channel, need to design corresponding search volume, and blind Detecting number of times is identical with the down control channel of LTE R8.

Summary of the invention

For the problems referred to above, the object of the invention is to propose a kind of method that strengthens search volume in control channel.

The method of search volume in the enhancing control channel that the present invention proposes, the down control channel of enhancing is made up of 3 ePDCCH groups, and the method comprises:

Step 1: base station configures two ePDCCH groups of each terminal monitoring, one is main ePDCCH group, another one is auxiliary ePDCCH group, the not identical main ePDCCH group of terminal configuration on the same group, different auxiliary ePDCCH groups;

Step 2: terminal is searched for public search space in main ePDCCH group, obtains common downlink control information.

Further, send mode comprises centralized transmission and distributed transmission, wherein,

For centralized transmission, each ePDCCH group is by 1 PRB to forming, and each PRB, facing to after removing demodulation pilot frequency RE, is divided into 16 eREG, an eCCE of 4 eREG compositions, and such ePDCCH group is made up of 4 eCCE;

For distributed transmission, each ePDCCH group is by 8 PRB to forming, and each PRB, to after removing demodulation pilot frequency RE, is divided into 16 eREG, an eCCE of 4 eREG compositions, and such ePDCCH group is made up of 32 eCCE.

Further, when terminal number is few, terminal just obtains the Downlink Control Information of terminal-specific at main ePDCCH group searching, and now auxiliary ePDCCH group sends as data.

Further, in the time that terminal number increases, except searching for main ePDCCH group, the not different ePDCCH group of terminal searching on the same group.

Further, when polymerization grade is 1,2 and 4, terminal is carried out blind Detecting in the ePDCCH of centralized transmission group; In the time that polymerization grade is 8 and 16, terminal is carried out blind Detecting in the ePDCCH of distributed transmission group.

The present invention has designed new public search space and the search volume of terminal-specific, and terminal blind decoding number of times is remained unchanged.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of group main in the preferred embodiment of the inventive method;

Fig. 2 is the schematic diagram of assisted group #2 in the preferred embodiment of the inventive method;

Fig. 3 is the schematic diagram of assisted group #3 in the preferred embodiment of the inventive method.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearer, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that embodiment described herein is only for explaining the present invention, rather than for limiting the present invention.

According to the present invention, the down control channel of enhancing is made up of 3 ePDCCH groups.

For centralized transmission, each ePDCCH group is by 1 PRB to forming, and each PRB, facing to after removing demodulation pilot frequency RE, is divided into 16 eREG, an eCCE of 4 eREG compositions, and such ePDCCH group is made up of 4 eCCE.

If there is PDCCH and CRS, the number of the REs that each eCCEs comprises can be less than 36 REs, as considered, 3 OFDM symbols are as PDCCH, and 4 CRS ports, only have 23 available REs as eCCE, will have influence on like this performance of covering, therefore defined higher polymerization grade 16.

In order to improve resource utilization, UEs will have some flexibilities to select to monitor not ePDCCH resource on the same group, and configure a public resource and use to all terminals, and auxiliary resource, only use when main group is blocked.Public search space is also defined in main group.

In a preferred embodiment of the invention, as Figure 1-3, there are three ePDCCH groups in system side, it is main group that Fig. 1 shows ePDCCH group #1, and Fig. 2 and Fig. 3 show ePDCCH group #2 and #3 as auxiliary group, configuration is to 2 ePDCCH groups of each UE, ePDCCH group #1 is that all UEs share, and UEs does not on the same group distribute to different assisted group, and first the control information of all terminals is distributed in main group, if exist and block on main group, be redistributed in assisted group.The configuration of the main and assisted group based on such, in the time that terminal is few, main group sends as ePDCCH, assisted group sends as data, only, when terminal number is many, assisted group is used as ePDCCH, and because the different auxiliary different UEs of component dispensing, identical assisted group is shared by little terminal, and the blocking probability in assisted group diminishes.

The setting of corresponding search volume as Figure 1-3, in main group of #1, configure 1,2,4,8 and 16 polymerization grade, corresponding space size is 4,4,4,8 and 16, in assisted group #2, configure 1,4 and 16 polymerization grade, corresponding space size is 2,4 and 16, in assisted group #3, configure 2 and 8 polymerization grade, corresponding space size is 4 and 8.When can obtaining thus upstream data and be single codeword and send, the terminal two kinds of dissimilar DCI that need to attempt decoding, need to be terminal-specific search volume search 32 times, identical with the searching times of PDCCH.

Thus, can obtain search volume in multiple groups, each terminal as shown in the table:

Search volume in multiple groups, table 3-each terminal

In addition, because centralized transmission (localized transmission) is more suitable in oligomerization grade as wave beam forming, distributed transmission (distributed transmission) is more suitable for obtaining diversity gain in high polymerization grade, therefore design the centralized transmission of time standby of

polymerization grade

1,2 and 4, corresponding searching times is 12, polymerization grade is 8 and 16 the distributed transmission of time standby, and corresponding searching times is 4.

The search volume of the different send modes of table 4-

Polymerization grade	Distributed transmission candidate collection	Centralized transmission candidate collection
			1	0	6
2	0	4
			4	0	2
8	2	0
			16	2	0

The polymerization grade of public search space is 8 and 16, adopts distributed transmission, and corresponding space size is 32 eCCE.Due to need to the decode DCI of two kinds of different length types of terminal, need to maximum 12 blind checks in public search space, identical with the searching times of PDCCH

Polymerization grade	Candidate collection
			8	4

16

2

The down control channel strengthening is used for expanding and covers, and improves the spectrum efficiency of down control channel.Different from the down control channel of LTE R8, Downlink Control Information is not to send on front 3 OFDM symbols, but send in the position that sends downlink data, therefore the definition of corresponding eREG and eCCE all needs to carry out new definition, and in order to there is identical covering with the PDCCH of R8, increase higher polymerization grade, in order not increase the complexity of terminal, the number of times of blind decoding will remain unchanged.

As can be seen here, terminal-specific search volume and public search space in the enhancing control channel of this patent design, all identical with PDCCH of corresponding searching times.

Above are only preferred embodiment of the present invention, certainly, can also have other execution mode with further exploration according to actual needs.But, should be clear and definite, based on similar the conversion above-mentioned or execution mode with same idea that other is not explained out, all should be encompassed among the protection range of the claims in the present invention.

Claims

1. a method that strengthens search volume in control channel, is characterized in that, the down control channel of enhancing is made up of 3 ePDCCH groups, and the method comprises:

2. method according to claim 1, is characterized in that, send mode comprises centralized transmission and distributed transmission, wherein,

3. method according to claim 1, is characterized in that, when terminal number is few, terminal just obtains the Downlink Control Information of terminal-specific at main ePDCCH group searching, and now auxiliary ePDCCH group sends as data.

4. method according to claim 1, is characterized in that, in the time that terminal number increases, and except searching for main ePDCCH group, the not different ePDCCH group of terminal searching on the same group.

5. method according to claim 2, is characterized in that, when polymerization grade is 1,2 and 4, terminal is carried out blind Detecting in the ePDCCH of centralized transmission group; In the time that polymerization grade is 8 and 16, terminal is carried out blind Detecting in the ePDCCH of distributed transmission group.