WO2014016672A1

WO2014016672A1 - Method of configuring ecce for epdcch

Info

Publication number: WO2014016672A1
Application number: PCT/IB2013/001644
Authority: WO
Inventors: Qi JIANG; Zheng Liu; Matthew Baker
Original assignee: Alcatel Lucent
Priority date: 2012-07-27
Filing date: 2013-07-09
Publication date: 2014-01-30
Also published as: CN103582135A; CN103582135B; TW201417606A

Abstract

The invention provides a method, in a network entity of a communication system, of configuring ECCE for EPDCCH. According to an embodiment of the invention, the network entity could determine the number of ECCE and the resource elements occupied by each ECCE according to the number of available resource elements in a physical resource block pair. According to another embodiment of the invention, the network entity could further determine the number of e REGs occupied by one ECCE and the number of resource elements occupied by each e REG. With the preferable embodiments according to the invention, some original configuration of previous PDCCH could be compatible, and the standardization will be accelerated.

Description

Method of Configuring ECCE for EPDCCH

Field of the invention

The present disclosure relates to communication systems, and particularly to a method of configuring ECCE for EPDCCH.

Background of the invention

For the present PDCCH (Physical Downlink Control Channel), each PDCCH use one or more CCE (Control Channel Element) to transport information, wherein each CCE corresponds to 9 groups of REG (Resource Element Group), each group includes 4 Res (Resource Element).

In 3 GPP Rel-11, the design of EPDCCH (Enhanced Physical Downlink Control Channel) is under discussion based on considerations from enhance interference coordination (elCIC), CA enhancement, new carrier type, CoMP and DL MIMO. As EPDCCH will be located in the data region, it is required to design new different rules for EPDCCH as PDCCH. Further, the following features should be taken into accounts: ECCE/eREG (enhanced Control Channel Element/enhanced Resource Element Group) definition, whether to support eREG level cross interleaving, and resource element mapping rules. Herein each EPDCCH uses ECCE to transport information.

In RANI meeting #69bis, some agreement for RE mapping rules during the collision with legacy signals has been agreed. For example, a base station and an user equipment can use coding chain rate-matching when one or more of the following situations occurs: 1. setting common reference signal; 2. setting new antenna port on new carrier type; 3 the various situations in which PDCCH occupies OFDM symbols (for example, occupies 1 symbol, 2 symbols , 3 symbols); 4. setting PBCH and PSS/SSS. Further, the meeting also agrees that ZP (zero power) CSI-RS and NZP (non zero power ) CSI-RS is configured an user equipment based on the specific situations.

However, until now, the detailed design and configuration for ECCE of EPDCCH has not been discussed, for example, the number of ECCEs in a physical resource block pair, the number of resource element included by each ECCE, whether to support a flexible number of ECCEs/eREGs, the number of eREGs included by each ECCE and the number of resource elements occupies by each eREG. Summary of the invention

Thus, the prior art is lack of the research for the detailed configuration of ECCE.

Therefore, in view of the problem present in the prior art, according to a first aspect of the invention, a method, in a network entity of a communication system, of configuring ECCE for EPDCCH is provided, wherein the method comprises the following step: a. determining number of ECCEs in a physical resource block pair and number of resource elements occupied by each ECCE.

According to an embodiment of the present invention, the step a further includes ; al l . determining number of available resource elements in the physical resource block pair; al2. determining the number of ECCEs in the physical resource block pair as 4, and determining average number of resource elements occupied by each ECCE based on the number of ECCEs in the physical resource block pair; and al 3. determining the average number of resource elements occupied by each ECCE as the number of resource elements occupied by each ECCE, when the average number of resource elements occupied by each ECCE is an integer, and when the average number of resource elements occupied by each ECCE is not an integer, implementing step al3-l or al 3-2: al 3-l . the network entity including a base station and an user equipment, and when the base station shares a first predefined rule with the user equipment, the base station and the user equipment determining the number of resource elements occupied by each ECCE based on the first predefined rule; al3-2. the network entity including a base station and an user equipment, and when the base station does not share a first predefined rule with the user equipment, the base station determining the number of resource elements occupied by each ECCE based on the first predefined rule, and sending a first message to the user equipment, the first message indicating ECCE occupied by the user equipment and number of resource elements occupied by the ECCE, and the user equipment receiving the first message from the base station and determining ECCE occupied by itself and number of resource elements occupied by the ECCE based on the first message.

The above embodiment describes a method of configuring the number of ECCEs in a physical resource block pair fixedly, thus simplifying the implementation progress.

According to an embodiment of the present invention, the step a further includes:a21. determining number of available resource elements in the physical resource block pair;a22. determining a first number of ECCEs and determining average number of resource elements occupied by each ECCE based on the first number of ECCEs, when the number of available resource elements in the physical resource block pair is higher than or equal to a first threshold, and when the number of available resource elements in the physical resource block pair is lower than the first threshold, determining a second number of ECCEs and determining average number of resource elements occupied by each ECCE based on the second number of ECCEs; and a23. determining the average number of resource elements occupied by each ECCE as the number of resource elements occupied by each ECCE, when the average number of resource elements occupied by each ECCE is an integer, and when the average number of resource elements occupied by each ECCE is not an integer, implementing step a23-l or a23-2: a23-l . the network entity including a base station and an user equipment, and when the base station shares a second predefined rule with the user equipment, the base station and the user equipment determining the number of resource elements occupied by each ECCE based on the second predefined rule;a23-2. the network entity including a base station and an user equipment, and when the base station does not share a second predefined rule with the user equipment, the base station determining the number of resource elements occupied by each ECCE based on the second predefined rule, and sending a second message to the user equipment, the second message indicating ECCE occupied by the user equipment and number of resource elements occupied by the ECCE, and the user equipment receiving the second message from the base station and determining ECCE occupied by itself and the number of resource elements occupied by the ECCE based on the second message.

The above embodiment describes a method of configuring the number of ECCEs in a physical resource block pair flexibly. Thus, the number of ECCEs could be flexibly configured according to the available resource elements in the current physical resource block pair, therefore optimizing the implementation progress.

According to an embodiment of the present invention, the first predefined rule and/or the second predefined rule includes minimizing difference between the numbers of resource elements occupied by each ECCE. Since that if there are two or multiple ECCEs in a continuous resource, the channel fading sensed by them is similar, it can use the ways, in which the difference between the numbers of resource elements occupied by each ECCE is minimized, to allocate resource elements for each ECCE when the average number of resource elements occupies by each ECCE is not a integer. For example, if there are 63 resource elements available and there are two ECCEs, then 31 resource elements could be allocated for one ECCE, and 32 resource elements could be allocated for another ECCE. Although the second ECCE has been allocated by one more resource element, the base station can handle the above situation by using intensive code rate, adjusting power allocation (for example, adjusting the power of the last resource element), for example, since the coding is very flexible in the real system.

According to an embodiment of the present invention, the first number of ECCEs is 4, and the second number of ECCEs is 2. By such configuration, the number of ECCEs in the physical resource block could be matched with the current aggregation level { 1 , 2, 4, 8 }, thus facilitate the blind decoding of EPDCCH.

According to an embodiment of the present invention, the first threshold is 72. Herein, there are 168 physical elements in a physical resource block pair, and the decoding of EPDCCH is based on DM-RS transported in the physical resource block pair allocated to DCI transportation. Now, DM-RS requires 24 resource elements, and thus there are 144 remaining resource elements in the physical resource block pair, which means there are maximal available 144 resource elements in the physical resource block. Thus, 72 is a middle value. In another aspect, since in the CCE current used by the existing PDCCH, each CCE has 36 resource elements, then the selection of 72 corresponds to the number of resource elements occupies by two former CCE. Therefore, the compatibility with the former configuration could be improved.

According to an embodiment of the present invention, the method further comprises step b: b. determining number of eREGs occupied by one ECCE and number of resource elements occupied by each eREG.

According to an embodiment of the present invention, the step b further includes: bl l . determining the number of eREGs occupied by one ECCE as 4, and determining average number of resource elements occupied by each eREG; and bl2. determining the average number of resource elements occupied by each eREG as the number of resource elements occupied by each eREG, when the average number of resource elements occupied by each eREG is an integer, and when the average number of resource elements occupied by each eREG is not an integer, implementing step b l2- l or b l2-2: bl2-l . the network entity including a base station and an user equipment, and when the base station shares a third predefined rule with the user equipment, the base station and the user equipment determining the number of resource elements occupied by each eREG based on the third predefined rule; bl2-2. the network entity including a base station and an user equipment, and when the base station does not share a third predefined rule with the user equipment, the base station determining the number of resource elements occupied by each eREG based on the third predefined rule, and sending a third message to the user equipment, the third message indicating number of resource elements occupied by each eREG occupied by the user equipment, and the user equipment receiving the third message from the base station and determining number of resource elements occupied by each eREG occupied by itself based on the third message.

The above embodiment describes a method of configuring the number of eREGs occupied by ECCE in a physical resource block pair fixedly, thus simplifying the implementation progress.

According to an embodiment of the present invention, the step b further includes: b21. determining that one ECCE occupies a third number of eREGs, and determining the average number of resource elements occupied by each eREG, when the determined number of resource elements occupied by ECCE is higher than or equal to a second threshold, and when the determined number of resource elements occupied by ECCE is lower than the second threshold, determining that one ECCE occupies a fourth number of eREGs, and determining the average number of resource elements occupied by each eREG; and b22. determining the average number of resource elements occupied by each eREG as the number of resource elements occupied by each eREG, when the average number of resource elements occupied by each eREG is an integer, and when the average number of resource elements occupied by each eREG is not an integer, implementing step b22-l or b22-2: b22-l . the network entity including a base station and an user equipment, and when the base station shares a fourth predefined rule with the user equipment, the base station and the user equipment determining the number of resource elements occupied by each eREG based on the fourth predefined rule; b22-2. the network entity including a base station and an user equipment, and when the base station does not share a fourth predefined rule with the user equipment, the base station determining the number of resource elements occupied by each eREG based on the fourth predefined rule, and sending a fourth message to the user equipment, the fourth message indicating number of resource elements occupied by each eREG occupied by the user equipment, and the user equipment receiving the fourth message from the base station and determining number of resource elements occupied by each eREG occupied by itself based on the fourth message.

The above embodiment describes a method of configuring the number of eREGs occupied by ECCE in a physical resource block pair flexibly. Thus, the number of eREGs could be flexibly configured according to the available resource elements in the current physical resource block pair, and thus according to the average number of resource elements occupied by each ECCE, therefore optimizing the implementation progress.

According to an embodiment of the present invention, the third predefined rule and/or the fourth predefined rule includes minimizing difference between the numbers of resource elements occupied by each eREG.

According to an embodiment of the present invention, the third number of eREGs is 4, and the fourth number of eREGs is 2.

According to an embodiment of the present invention, the second threshold is 16.

According to the preferable embodiment of the present invention, it could be compatible with the original configuration of previous PDCCH. And the standardization will be accelerated. Brief description of drawings

Other features, objects and advantages of the invention will become more apparent upon review of the following detailed description of non-limiting embodiments taken with reference to the drawings in which:

Fig.l illustrates a method flowchart according to an embodiment of the present invention;

Fig.2 illustrates a method flowchart of step SI in Fig.l according to an embodiment of the present invention;

Fig.3 illustrates a method flowchart of step SI in Fig.l according to another embodiment of the present invention;

Fig.4 illustrates a method flowchart of step S2 in Fig.l according to an embodiment of the present invention; and

Fig.5 illustrates a method flowchart of step S2 in Fig.l according to another embodiment of the present invention.

Identical or like reference numerals denote identical or like components or features throughout the different figures in the drawings.

Detailed description of embodiments

Fig.l illustrates a method flowchart according to an embodiment of the present invention. As shown in Fig. l, the method of the present invention consists of 2 portions, step SI determining number of ECCEs in a physical resource block pair and number of resource elements occupied by each ECCE and step S2 determining number of eREGs occupied by one ECCE and number of resource elements occupied by each eREG. The step S I and step S2 are carried by a network entity. In the description of the present invention, the network entity includes a base station and an user equipment.

Fig.2 illustrates a method flowchart of step SI in Fig.l according to an embodiment of the present invention. In the embodiment described in Fig.2, 4 ECCEs are fixedly selected in one physical resource block pair.

Specifically, in step S201 , the network entity determines number of available resource elements in the physical resource block pair. There are 168 resource elements in a physical resource block pair, and the decoding of EPDCCH is based on DM-RS transported in the physical resource block pair allocated to DCI transportation. Now DM-RS requires 24 resource elements, and thus there are 144 remaining resource elements in the physical resource block pair. Therefore, the network entity needs to determine the number of the available resource elements among those 144 resource elements.

When the network entity is a base station, it will determine number of available resource elements in the physical resource block pair, according to the resource elements in the physical resource block pair occupied by other signals. Specifically, for example, the base station could determine number of available resource elements in the physical resource block pair based on the OFDM symbols occupied by PDCCH, the antenna ports of CRS, if there is CSI-RS in the physical resource block pair and etc. Preferably, the base station could determine number of available resource elements in the physical resource block pair by determining if PBCH, PSS/SSS are transported in the physical resource block pair. It is appreciated for those skilled in the art, the base station could determine number of available resource elements in the physical resource block pair based on the one or more of abovementioned or unmentioned condition.

When the network entity is a user equipment, since the user equipment will also know the existence of PDCCH, CRS, PSS, SSS, PBCH, CSI-RS and their configuration, then the user equipment will implicitly predict the number of the available resource elements.

Then, the network entity divides the number of available resource elements by the number for ECCEs (here, 4), so as to determine average number of resource elements occupied by each ECCE. For example, when there are 144 resource elements available, the average number of resource elements occupied by each ECCE is 36. When there are 72 resource elements available, the average number of resource elements occupied by each ECCE is 18. When there are 106 resource elements available, the average number of resource elements occupied by each ECCE is 26.5.

When the average number of resource elements occupied by each ECCE is an integer, the method goes into the step S203. In the step S203, the network entity determines the average number of resource elements occupied by each ECCE as the number of resource elements occupied by each ECCE. For the situation of 144 available resource elements, the number of the resource elements occupied by 4 ECCEs is determined as 36, 36, 36, 36 respectively.

When the average number of resource elements occupied by each ECCE is not an integer, it is necessary to determine whether the base station and the user equipment share a first predefined rule. When the base station and the user equipment share a first predefined rule, the method goes into the step S204. Otherwise, the method goes into the step S205.

Specifically, for the situation in which 106 resource elements are available, and the average number of resource elements occupied by each ECCE is 26.5, if the base station and the user equipment share (predefine) a rule, in which the number of the resource elements for those 4 ECCEs is set for 26, 26, 27, 27 respectively, the base station and the user equipment could determine the number of the resource elements occupied by each of 4 ECCEs according to this predefined rule. Herein, the predefined rule is preferably set as minimizing difference between the numbers of resource elements occupied by each ECCE. However, other applicable rules have not been excluded herein. For example, the predefined rule shared by the base station and the user equipment could also be 28, 28, 25, 25.

When the base station has not shared the above rule with the user equipment, the base station determines the number of resource elements occupied by each ECCE based on the predefined rule, that is, determines 26, 26, 27, 27, and sends a first message to the user equipment, which indicates the ECCE occupied by the user equipment and the number of the resource elements occupied by the ECCE (this message could be implemented by the control information of common searching space or a high layer signaling, for example, radio resource control ). Then, the user equipment determines the ECCE occupied by itself and the number of resource elements occupied by the ECCE based on the first message.

In a varied embodiment, when the base station uses a different rule as the first predefined rule to determine the number of the resource elements occupied by each ECCE, for example, in the above embodiment, the number of the resource elements occupied by each ECCE has been set as 28, 26, 25, 27 or 30, 22, 27, 27 and etc, the base station could also use the first message to notify the user equipment the above configuration, so as to facilitate the proceeding progress of the user equipment.

In another varied embodiment, if those 4 ECCEs correspond to 2 user equipments, for example, the base station preferably needs to send information to those 2 user equipments, so as to notify the corresponding ECCE of those 2 user equipments and the number of the resource elements in the corresponding ECCE to avoid the unnecessary blind decoding of the user equipment.

Therefore, through the step S205, when the predefined rule has not been shared, the user equipment could receive the first message from the base station, and thus determines the ECCE occupied by itself and the number of the resource elements occupied by the ECCE. Of course, even under the situation in which multiple user equipments exist, the user equipment could also obtain the ECCE occupied by other user equipments and the number of the resource elements occupied by the ECCE via suitable signalings.

In summary, in the steps shown in Fig.2, the base station and the user equipment (network entity) could implement steps S201, S202, S203 and S204 independently and respectively. Only in the step S205, an additional message is sent by the base station to interact with the user equipment, so as to accomplish the ECCE configuration for EPDCCH.

Fig.3 illustrates a method flowchart of step SI in Fig.l according to another embodiment of the present invention. The embodiment shown in Fig. 3 describes a method of configuring the number of ECCEs in a physical resource block pair flexibly, such that the number of ECCEs could be flexibly configured according the available resource elements in the current physical resource block pair. Thereby, the implementation is optimized.

Specifically, the step S301 is similar with the step S201 in Fig.2, during which, the network entity determines the number of available resource elements in the physical resource block pair. This determination progress is similar with the progress in the step S201 , and thus will not be described in detail here. In the step S302, when the number of available resource elements is higher than or equal to a first threshold, the network entity determines a first number of ECCEs, and determines the average number of resource elements occupied by each ECCE based on the first number of ECCEs. When the number of available resource elements is lower than a first threshold, the network entity determines a second number of ECCEs, and determines the average number of resource elements occupied by each ECCE based on the second number of ECCEs.

Specifically, for the purpose of illustration, the first number of ECCEs is set as 2, and the second number of ECCEs is set as 4, the first threshold is set as 72. It should be noted, those values are only preferable (their advantages have been described above and will not be described in detail herein), but not limited. The selection of other thresholds and/or the number of ECCEs will not influence the implementation of the scheme. For example, the first threshold could also be set as 80, 90 and etc. The first number of ECCEs could be set as 3, and the second number of ECCEs could be set as 6 and other suitable values. The selection of values depends on the detailed implantation of the scheme. For example, it is possible that EPDCCH would not be transported in a frame, when the number of resource elements included in ECCE is too low.

In the following, the first number of ECCEs is set as 2, the second number of ECCEs is set as 4 and the first threshold is set as 72.

Specifically, table 1 and table 2 show ECCE configuration under the situation in which the physical resource block pair has not PBCH, PSS, SSS and under the situation in which the physical resource block pair has PBCH, PSS, SSS, respectively (herein table 1 and table 2 is only used for the purpose of illustration, but not for limitation). Further, since in the progress of standardization whether EPDCCH will be transported in the situation, in which the physical resource block pair has PBCH, PSS, SSS, will be discussed, the configuration of ECCE has be categorized into table 1 and table 2.

PDCCH CRS PBCH PSS/SSS CSI-RS number of average number of REs symbols(the ports(the available in each ECCE

number required REs 4 ECCEs 2 ECCEs of number of per PRB per PRB occupied REs) pair pair

REs)

0 0 No No No 144 36 72

0 1 (8 REs) No No No 136 34 68

Yes (8

0 0 No No REs) 136 34 68

0 2 (16 REs) No No No 128 32 64

Yes (8

0 1 (8 REs) No No REs) 128 32 64

1 (10 REs) 1 (8 REs) No No No 126 31 .5 63

0 4 (24 REs) No No No 120 30 60

Yes (8

0 2 (16 REs) No No REs) 120 30 60

1 (8 REs) 2 (16 REs) No No No 120 30 60

Yes (8

1 (10 REs) 1 (8 REs) No No REs) 118 29.5 59

Yes (8

1 (8 REs) 2 (16 REs) No No REs) 114 28.5 57

2 (22 REs) 1 (8 REs) No No No 114 28.5 57

Yes (8

0 4 (24 REs) No No REs) 112 28 56

1 (8 REs) 4 (24 REs) No No No 112 28 56

Yes (8

1 (8 REs) 4 (24 REs) No No REs) 112 28 56

2 (20 REs) 2 (16 REs) No No No 108 27 54

Yes (8

2 (22 REs) 1 (8 REs) No No REs) 106 26.5 53

2 (16 REs) 4 (24 REs) No No No 104 26 52

3 (34 REs) 1 (8 REs) No No No 102 25.5 51

Yes (8

2 (20 REs) 2 (16 REs) No No REs) 100 25 50

Yes (8

2 (16 REs) 4 (24 REs) No No REs) 96 24 48

3 (32 REs) 2 (16 REs) No No No 96 24 48

Yes (8

3 (34 REs) 1 (8 REs) No No REs) 94 23.5 47 3 (28 REs) 4 (24 REs) No No No 92 23 46

Yes (8

3 (32 REs) 2 (16 REs) No No REs) 88 22 44

Yes (8

3 (28 REs) 4 (24 REs) No No REs) 84 21 42

Table 1 (the physical resource block pair has not PBCH, PSS, SSS)

REs)

Yes (12

0 0 No REs) No 132 33 66

Yes (12

0 1 (8 REs) No REs) No 124 31 62

Yes (12 Yes (8

0 0 No REs) REs) 124 31 62

Yes (12

0 1 (16 REs) No REs) No 116 29 58

Yes (12 Yes (8

0 1 (8 REs) No REs) REs) 116 29 58

Yes (12

1 (10 REs) 1 (8 REs) No REs) No 114 28.5 57

Yes (12

0 4 (24 REs) No REs) No 108 27 54

Yes (12 Yes (8

0 2 (16 REs) No REs) REs) 108 27 54

Yes (12

1 (8 REs) 1 (16 REs) No REs) No 108 27 54

Yes (12 Yes (8

1 (10 REs) 1 (8 REs) No REs) REs) 106 26.5 53

Yes (12

2 (22 REs) 1 (8 REs) No REs) No 102 25.5 51

Yes (12 Yes (8

0 4 (24 REs) No REs) REs) 100 25 50

Yes (12

1 (8 REs) 4 (24 REs) No REs) No 100 25 50

Yes (12 Yes (8

1 (8 REs) 2 (16 REs) No REs) REs) 100 25 50

0 0 Yes (48 No No 96 24 48 REs)

Yes (12

(20 REs) 1 (16 REs) No REs) No 96 24 48

Yes (12 Yes (8

(22 REs) 1 (8 REs) No REs) REs) 94 23.5 47

Yes (12 Yes (8

(8 REs) 4 (24 REs) No REs) REs) 92 23 46

Yes (12

(16 REs) 4 (24 REs) No REs) No 92 23 46

Yes (46

0 1 (8 REs) REs) No No 90 22.5 45

Yes (12

(34 REs) 1 (8 REs) No REs) No 90 22.5 45

Yes (48 Yes (8

0 0 REs) No REs) 88 22 44

Yes (12 Yes (8

(20 REs) 2 (16 REs) No REs) REs) 88 22 44

Yes (12 Yes (8

(16 REs) 4 (24 REs) No REs) REs) 88 22 44

Yes (48 Yes (12

0 0 REs) REs) No 84 21 42

Yes (44

0 2 (16 REs) REs) No No 84 21 42

Yes (12

(32 REs) 1 (16 REs) No REs) No 84 21 42

Yes (46 Yes (8

0 1 (8 REs) REs) No REs) 82 20.5 41

Yes (12 Yes (8

(34 REs) 1 (8 REs) No REs) REs) 82 20.5 41

Yes (46

(10 REs) 1 (8 REs) REs) No No 80 20 40

Yes (40

0 4 (24 REs) REs) No No 80 20 40

Yes (12

(28 REs) 4 (24 REs) No REs) No 80 20 40

Yes (46 Yes (12

0 1 (8 REs) REs) REs) No 78 19.5 39

Yes (48 Yes (12 Yes (8

0 0 REs) REs) REs) 76 19 38

Yes (44 Yes (8

0 2 (16 REs) REs) No REs) 76 19 38

Yes (44

(8 REs) 2 (16 REs) REs) No No 76 19 38 (32 REs) 2 (16 REs) No Yes (12 Yes (8 76 19 38 REs) REs)

Yes (46 Yes (8

(10 REs) 1 (8 REs) REs) No REs) 72 18 36

Yes (44 Yes (12

0 2 (16 REs) REs) REs) No 72 18 36

Yes (40 Yes (8

0 4 (24 REs) REs) No REs) 72 18 36

Yes (40

(8 REs) 4 (24 REs) REs) No No 72 18 36

Yes (12 Yes (8

(28 REs) 4 (24 REs) No REs) REs) 72 18 36

Yes (46 Yes (12 Yes (8

0 1 (8 REs) REs) REs) REs) 70 17.5 35

Yes (46

(22 REs) 1 (8 REs) REs) No No 68 17 34

Yes (46 Yes (12

(10 REs) 1 (8 REs) REs) REs) No 68 17 34

Yes (44 Yes (8

(8 REs) 2 (16 REs) REs) No REs) 68 17 34

Yes (40 Yes (12

0 4 (24 REs) REs) REs) No 68 17 34

Yes (44

(20 REs) 2 (16 REs) REs) No No 64 16 32

Yes (44 Yes (12 Yes (8

0 2 (16 REs) REs) REs) REs) 64 16 32

Yes (40 Yes (8

(8 REs) 4 (24 REs) REs) No REs) 64 16 32

Yes (40

(16 REs) 4 (24 REs) REs) No No 64 16 32

Yes (46 Yes (8

(22 REs) 1 (8 REs) REs) No REs) 60 15 30

Yes (46 Yes (12 Yes (8

(10 REs) 1 (8 REs) REs) REs) REs) 60 15 30

Yes (44 Yes (12

(8 REs) 2 (16 REs) REs) REs) No 60 15 30

Yes (40 Yes (12 Yes (8

0 4 (24 REs) REs) REs) REs) 60 15 30

Yes (46

(34 REs) 1 (8 REs) REs) No No 56 14 28

Yes (46 Yes (12

(22 REs) 1 (8 REs) REs) REs) No 56 14 28

Yes (44 Yes (8

(20 REs) 2 (16 REs) REs) No REs) 56 14 28 (8 REs) 2 (16 REs) Yes (44 Yes (12 Yes (8 56 14 28 REs) REs) REs)

Yes (40 Yes (8

(16 REs) 4 (24 REs) REs) No REs) 56 14 28

Yes (40 Yes (12

(8 REs) 4 (24 REs) REs) REs) No 56 14 28

Yes (44

(32 REs) 2 (16 REs) REs) No No 52 13 26

Yes (44 Yes (12

(20 REs) 2 (16 REs) REs) REs) No 52 13 26

Yes (40

(28 REs) 4 (24 REs) REs) No No 52 13 26

Yes (40 Yes (12 Yes (8

(8 REs) 4 (24 REs) REs) REs) REs) 52 13 26

Yes (40 Yes (12

(16 REs) 4 (24 REs) REs) REs) No 52 13 26

Yes (46 Yes (8

(34 REs) 1 (8 REs) REs) No REs) 48 12 24

Yes (46 Yes (12 Yes (8

(22 REs) 1 (8 REs) REs) REs) REs) 48 12 24

Yes (46 Yes (12

(34 REs) 1 (8 REs) REs) REs) No 44 11 22

Yes (44 Yes (8

(32 REs) 2 (16 REs) REs) No REs) 44 11 22

Yes (44 Yes (12 Yes (8

(20 REs) 2 (16 REs) REs) REs) REs) 44 11 22

Yes (40 Yes (8

(28 REs) 4 (24 REs) REs) No REs) 44 11 22

Yes (40 Yes (12 Yes (8

(16 REs) 4 (24 REs) REs) REs) REs) 44 11 22

Yes (44 Yes (12

(32 REs) 2 (16 REs) REs) REs) No 40 10 20

Yes (40 Yes (12

(28 REs) 4 (24 REs) REs) REs) No 40 10 20

Yes (46 Yes (12 Yes (8

(34 REs) 1 (8 REs) REs) REs) REs) 36 9 18

Yes (44 Yes (12 Yes (8

(32 REs) 2 (16 REs) REs) REs) REs) 32 8 16

Yes (40 Yes (12 Yes (8

(28 REs) 4 (24 REs) REs) REs) REs) 32 8 16

Table 2 (the physical resource block pair has PBCH, PSS, SSS)

In the table 1 and table 2, the first row shows PDCCH symbols(the number of occupied REs), CRS ports (the required number of REs), PBCH, PSS/SSS, CSI-RS and the average number of REs in each ECCE under the situations in which one physical resource block pair has 4 ECCEs and one physical resource block pair has 2 ECCEs. In the tables, Yes stands for "has", No stands for "has not".

With respect to the tables 1 and 2, it should be noted that, the configuration of CSI-RS is very flexible. In the tables 1 and 2, CSI-RS has been set as occupying 8 resource elements, which is only an example. In practice, the number of the resource elements occupied by CSI-RS could be varied according to the configuration of the base station. Furthermore, since the decoding of PDCCH is conduct through CRS, if there is no CRS, then there is no necessary of the existence of PDCCH. For the fractions appearing tables 1 and 2, for example 31.5, it does not mean there exists a half resource elements, but instead, it only indicated the average number of the resource elements occupied by each ECCE. For example, when there are 4 ECCEs, these four ECCEs could has 31 , 32, 31 , 32 resource elements, respectively. Moreover, the rightest column of tables 1 and 2 shows the two situations in which one physical resource block pair has 4 ECCEs and one physical resource block pair has 2 ECCEs, which is only used to facilitate the blind decoding of the user equipment. Thus, other numbers of ECCEs not shown in tables 1 and 2 have not been excluded.

Further, it is appreciated for those skilled in the art, in the situation shown in the table 1 and 2, the number of the resource elements occupied by various signals could be obtained according to the frame construction. Thus, the number of the available resource elements in the physical resource block pair shown in the tables 1 and 2 can be obtained, and will not be described in detail herein.

For example, with reference to the seventh row in the table 1 , PDCCH occupies one OFDM symbol (10 resource elements), CRS has one antenna port (8 resource elements), and there is no PBCH, PSS/SSS, the number of current available resource elements could be determined as 126, by subtracting 18 resource elements from 144 resource elements after excluding 24 resource elements required by DM-RS. And since 126 is higher than the threshold 72, 4 ECCEs will be selected. By dividing 126 with 4, the average number of resource elements occupied by each ECCE could be obtained (in this example, 31.5). In another example, with reference to the 45th row in the table 2, PDCCH occupies 2 OFDM symbols (22 resource elements), CRS has one antenna port (8 resource elements), there exists PBCH (occupying 46 resource elements), there is no PSS/SSS, the number of current available resource elements could be determined as 68, by subtracting 76 resource elements from 144 resource elements after excluding 24 resource elements required by DM-RS. And since 68 is lower than the threshold 72, 2 ECCEs will be selected. By dividing 68 with 2, the average number of resource elements occupied by each ECCE could be obtained (in this example, 34).

In a preferable embodiment, the network entity (both base station and user equipment) has tables 1 and 2, and will configure ECCE according to the rule of step S302 and with the help of the tables 1 and 2, for example selecting the number of ECCEs, determining the average number of resource elements occupied by each ECCE. Of course, the base station and the user equipment could also need no tables 1 and 2, but instead, calculate the number of ECCEs in real time, and determine the average number of resource elements occupied by each ECCE according to the current available resource elements.

In summary, the base station and the user equipment could determine the number of ECCEs through the step S301 and the step S302, and thus determine the average number of resource elements occupied by each ECCE.

Then, when the average number of resource elements occupied by each ECCE is an integer, the method goes into the step S303.

The step S303 is similar with the step S203. In the step S303, the network entity determines the average number of resource elements occupied by each ECCE as the number of resource elements occupied by each ECCE. For the situation in which 144 resource elements are available, the number of the resource elements occupied by the 4 ECCEs could be determined as 36, 36, 36, 36.

Similar to the related steps in Fig. 2, when the average number of resource elements occupied by each ECCE is not a integer, it is need to determine whether the base station and the user equipment share a second predefined rule. When the base station and the user equipment share a second predefined rule, the method goes into the step S304. Otherwise, the method goes into the step S305. Herein, it should be noted, the second predefined rule could be identical or different with the above mentioned the first predefined rule.

The step 304 is similar to the corresponding step 204 in Fig.2. For the example, in which the average number of resource elements occupied by each ECCE is 31.5 under 4 ECCEs, if the base station and the user equipment shares (predefines) the rule in which the number of the resource elements of 4 ECCEs is set respectively as 31 , 32, 31 , 32, the base station and the user equipment could determine the number of the resource elements occupied by each of 4 ECCEs according to this predefined rule. Herein, the predefined rule is preferably set as minimizing difference between the numbers of resource elements occupied by each ECCE. However, other applicable rules have not been excluded herein. For example, the predefined rule shared by the base station and the user equipment could also be 32, 32, 32, 30.

When the base station has not shared the above rule with the user equipment, the base station determines the number of resource elements occupied by each ECCE based on the predefined rule, that is, determines 31, 32, 31 , 32, and sends a second message to the user equipment, which indicates the ECCE occupied by the user equipment and the number of the resource elements occupied by the ECCE (this message could be implemented by the control information of common searching space or a high layer signaling, for example, radio resource control ). Then, the user equipment determines the ECCE occupied by itself and the number of resource elements occupied by the ECCE based on the second message.

In a varied embodiment, when the base station uses a different rule as the second predefined rule to determine the number of the resource elements occupied by each ECCE, for example, in the above embodiment, the number of the resource elements occupied by each ECCE has been set as 33, 33, 30, 30 or 33, 32, 31, 30 and etc, the base station could also use the second message to notify the user equipment the above configuration, so as to facilitate the proceeding progress of the user equipment.

Therefore, through the step S305, when the predefined rule has not been shared, the user equipment could receive the second message from the base station, and thus determines the ECCE occupied by itself and the number of the resource elements occupied by the ECCE. Of course, even under the situation in which multiple user equipments exist, the user equipment could also obtain the ECCE occupied by other user equipments and the number of the resource elements occupied by the ECCE via suitable signalings.

In summary, in the steps shown in Fig.3, the base station and the user equipment (network entity) could implement steps S301, S302, S303 and S304 independently and respectively. Only in the step S305, an additional message is sent by the base station to interact with the user equipment, so as to accomplish the ECCE configuration for EPDCCH.

Fig.4 illustrates a method flowchart of step S2 in Fig.l according to an embodiment of the present invention. In the embodiment shown in Fig.4, the number of eREGs occupied by one ECCE is determined as 4 fixedly.

Specifically, in the step S401 , the network entity determines the number of eREGs occupied by one ECCE as 4, and determines the average number of resource elements occupied by each eREG. For example, with the reference to the embodiment according to Figs 2 and 3, the number of the resource elements occupied by each ECCE could be determined. Therefore, the number of the resource elements occupied by the ECCE could be divided by the number of eREG (here is 4) so as to determine the number of the resource elements occupied by each eREG. For example, in the situation in which there are 4 ECCEs, and each ECCE has 31, 32, 31, 32 resource elements, respectively, those values will be divided by 4, such that in the situation in which ECCE has 31 resource elements, the average resource elements occupied by each eREG is 7.75, and in the situation in which ECCE has 32 resource elements, the average resource elements occupied by each eREG is 8.

When the average number of resource elements occupied by each eREG is an integer, the method goes into the step S402. In the step 402, the network entity determines the average number of resource elements occupied by each eREG as the number of resource elements occupied by each eREG. For example, for the situation in which the average number of resource elements occupied by each eREG is 8, the number of the resource elements of each of 4 ECCEs is respectively determined as 8, 8, 8, and 8.

When the average number of resource elements occupied by each eREG is not an integer, it is necessary to determine whether the base station and the user equipment share a third predefined rule. When the base station and the user equipment share the third predefined rule, the method goes in the step S403. Otherwise, the method goes into the step S404.

Specifically, for example, for the situation in which the average number of resource elements occupied by each eREG is 7.75, if the base station and the user equipment shares (predefines) the rule in which the number of the resource elements of 4 eREGs is set respectively as 8, 8, 8,

7, the base station and the user equipment could the number of the resource elements occupied by each of 4 eREGs according to this predefined rule. Herein, the predefined rule is preferably set as minimizing difference between the numbers of resource elements occupied by each eREG. However, other applicable rules have not been excluded herein. For example, the predefined rule shared by the base station and the user equipment could also be 9, 8, 7, 7.

When the base station has not shared the above rule with the user equipment, the base station determines the number of resource elements occupied by each eREG based on the predefined rule, that is, determines

8, 8, 8, 7, and sends a third message to the user equipment, which indicates the number of resource elements occupied by each eREG occupied by the user equipment (this message could be implemented by the control information of common searching space or a high layer signaling, for example, radio resource control ). Then, the user equipment determines the number of resource elements occupied by each eREG occupied by itself based on the third message.

In a varied embodiment, when the base station uses a different rule as the third predefined rule to determine the number of the resource elements occupied by each eREG, for example, in the above embodiment, the number of the resource elements occupied by each 4 eREGs has been set as 6, 8, 8, 9 and etc, the base station could also use the third message to notify the user equipment the above configuration, so as to facilitate the proceeding progress of the user equipment.

Therefore, through the step S404, when the predefined rule has not been shared, the user equipment could receive the third message from the base station, and thus determines the number of resource elements occupied by the eREG occupied by itself.

In summary, in the steps shown in Fig.4, the base station and the user equipment (network entity) could implement steps S401, S402, S403 independently and respectively. Only in the step S404, an additional message is sent by the base station to interact with the user equipment, so as to accomplish the eREG configuration for EPDCCH, that is the ECCE configuration for EPDCCH.

Fig.5 illustrates a method flowchart of step S2 in Fig.l according to another embodiment of the present invention. The embodiment shown in Fig. 5 describes a method of configuring the number of eREGs occupied by ECCE in a physical resource block pair flexibly, such that the number of ECCEs could be flexibly configured according the available resource elements in the current physical resource block pair, and thus according to the average number of resource elements occupied by each ECCE. Thereby, the implementation is optimized.

Specifically, in step 501 , the number of resource elements occupied by each ECCE is determined by the embodiment according to Figs. 2 and 3. When the determined number of resource elements occupied by ECCE is higher than or equal to a second threshold, the network entity determines that one ECCE occupies a third number of eREGs, and determines the average number of resource elements occupied by each eREG, and when the determined number of resource elements occupied by ECCE is lower than the second threshold, the network entity determines that one ECCE occupies a fourth number of eREGs, and determines the average number of resource elements occupied by each eREG.

Specifically, only for the purpose of illustration herein, the third number of eREGs is set as 4, and the fourth number of eREGs is set as 2, the second threshold is set as 16. It should be noted, those values are only preferable, but not limited and fixed. It is appreciated for those skilled in the art, the selection of other thresholds and/or the number of eREGs will not influence the implementation of the scheme. The following discussion will be conduct based on that the third number of eREGs is set as 4, and the fourth number of eREGs is set as 2, the second threshold is set as 16.

Specifically, when the number of resource element occupied by ECCE is 36, since 36 is higher than 16, the number of eREGs will be set as 4, and thus the average number of resource elements occupied by each eREG is 9 (dividing 36 resource elements by 4 eREGs). When the number of resource elements occupied by ECCE is 15, for example, the number of eREGs will be set as 2, and thus the average number of resource elements occupied by each eREG is 7.5.

In summary, the base station and the user equipment could determine the number of eREG through the step S501, and thus determine the average number of resource elements occupied by each eREG.

Then, when the average number of resource elements occupied by each eREG is an integer the method goes into the step S502. In the step S502, the network entity determines the average number of resource elements occupied by each eREG as the number of resource elements occupied by each eREG. For example, for the situation in which the number of the resource elements occupied by ECCE is 36, for example, and the average number of resource elements occupied by each eREG is 9, the number of resource elements occupied by 4 eREGs is determined as 9, 9, 9, 9, respectively. When the average number of resource elements occupied by each eREG is not an integer, it is necessary to determine whether a fourth predefined rule is shared between the base station and the user equipment. When the base station shares the fourth predefined rule with the user equipment, the method goes into the step S503. Otherwise, the method goes into the step 504. Herein, it should be noted, the fourth predefined rule could be identical with the above third predefined rule, but could be also different with the above third predefined rule.

Specifically, similar with the step S404 in Fig. 4, for the situation in which 4 eREGs exist and the average number of resource elements occupied by each eREG is 7.75, if the base station and the user equipment shares (predefines) the rule in which the number of the resource elements of 4 eREGs is set respectively as 8, 8, 8, 7, the base station and the user equipment could determine the number of the resource elements occupied by each of 4 eREGs according to this predefined rule. Herein, the predefined rule is preferably set as minimizing difference between the numbers of resource elements occupied by each eREG. However, other applicable rules have not been excluded herein. For example, the predefined rule shared by the base station and the user equipment could also be 9, 8, 7, 7.

When the base station has not shared the above rule with the user equipment, the base station determines the number of resource elements occupied by each eREG based on the predefined rule, that is, determines 9, 8, 7, 7, and sends a fourth message to the user equipment, which indicates the number of resource elements occupied by each eREG occupied by the user equipment (this message could be implemented by the control information of common searching space or a high layer signaling, for example, radio resource control ). Then, the user equipment determines the number of resource elements occupied by each eREG occupied by itself based on the fourth message. In a varied embodiment, when the base station uses a different rule as the fourth predefined rule to determine the number of the resource elements occupied by each eREG, for example, in the above embodiment, the number of the resource elements occupied by each 4 eREGs has been set as 6, 8, 8, 9 and etc, the base station could also use the fourth message to notify the user equipment the above configuration, so as to facilitate the proceeding progress of the user equipment. Therefore, through the step S504, when the predefined rule has not been shared, the user equipment could receive the fourth message from the base station, and thus determines the number of resource elements occupied by the eREG occupied by itself.

In summary, in the steps shown in Fig.5, the base station and the user equipment (network entity) could implement steps S501, S502, S503 independently and respectively. Only in the step S504, an additional message is sent by the base station to interact with the user equipment, so as to accomplish the eREG configuration for EPDCCH, that is the ECCE configuration for EPDCCH.

Those skilled in the art shall appreciate that the foregoing embodiments are illustrative but not limiting. Different technical features appearing in different embodiments can be combined to advantage. Those skilled in the art can appreciate and make other variant embodiments of the disclosed embodiments upon review of the drawings, the description and the claims. For example, the related signaling is used instead of the predefined steps, shared steps, and vice versa.

In the claims, the term "comprising" will not preclude another device(s) or step(s); the definite article "a" or "an" will not preclude plural; and the terms "first", "second", etc., are intended to designate a name but not to suggest any specific order. Any reference numerals shall not be construed as limiting the claimed scope. Functions of a plurality of elements appearing in a claim can be performed by a single element.

Claims

1. A method, in a network entity of a communication system, of configuring ECCE for EPDCCH, wherein the method comprises the following step:

a. determining number of ECCEs in a physical resource block pair and number of resource elements occupied by each ECCE.

2. A method according to claim 1 , wherein the step a further includes; al l . determining number of available resource elements in the physical resource block pair;

al2. determining the number of ECCEs in the physical resource block pair as 4, and determining average number of resource elements occupied by each ECCE based on the number of ECCEs in the physical resource block pair; and

al 3. determining the average number of resource elements occupied by each ECCE as the number of resource elements occupied by each ECCE, when the average number of resource elements occupied by each ECCE is an integer, and when the average number of resource elements occupied by each ECCE is not an integer, implementing step al 3-l or al 3-2:

al3-l . the network entity including a base station and an user equipment, and when the base station shares a first predefined rule with the user equipment, the base station and the user equipment determining the number of resource elements occupied by each ECCE based on the first predefined rule;

al3-2. the network entity including a base station and an user equipment, and when the base station does not share a first predefined rule with the user equipment, the base station determining the number of resource elements occupied by each ECCE based on the first predefined rule, and sending a first message to the user equipment, the first message indicating ECCE occupied by the user equipment and number of resource elements occupied by the ECCE, and the user equipment receiving the first message from the base station and determining ECCE occupied by itself and number of resource elements occupied by the ECCE based on the first message.

3. A method according to claim 1 , wherein the step a further includes: a21. determining number of available resource elements in the physical resource block pair;

a22. determining a first number of ECCEs and determining average number of resource elements occupied by each ECCE based on the first number of ECCEs, when the number of available resource elements in the physical resource block pair is higher than or equal to a first threshold, and when the number of available resource elements in the physical resource block pair is lower than the first threshold, determining a second number of ECCEs and determining average number of resource elements occupied by each ECCE based on the second number of ECCEs; and

a23. determining the average number of resource elements occupied by each ECCE as the number of resource elements occupied by each ECCE, when the average number of resource elements occupied by each ECCE is an integer, and when the average number of resource elements occupied by each ECCE is not an integer, implementing step a23-l or a23-2:

a23-l . the network entity including a base station and an user equipment, and when the base station shares a second predefined rule with the user equipment, the base station and the user equipment determining the number of resource elements occupied by each ECCE based on the second predefined rule;

a23-2. the network entity including a base station and an user equipment, and when the base station does not share a second predefined rule with the user equipment, the base station determining the number of resource elements occupied by each ECCE based on the second predefined rule, and sending a second message to the user equipment, the second message indicating ECCE occupied by the user equipment and number of resource elements occupied by the ECCE, and the user equipment receiving the second message from the base station and determining ECCE occupied by itself and the number of resource elements occupied by the ECCE based on the second message.

4. A method according to claim 2 or 3, wherein the first predefined rule and/or the second predefined rule includes minimizing difference between the numbers of resource elements occupied by each ECCE.

5. A method according to claim 3, wherein the first number of ECCEs is 4, and the second number of ECCEs is 2.

6. A method according to claim 3, wherein the first threshold is 72.

7. A method according to claim 2 or 3, wherein the method further comprises step b:

b. determining number of eREGs occupied by one ECCE and number of resource elements occupied by each eREG.

8. A method according claim 7, wherein the step b further includes:

bl l . determining the number of eREGs occupied by one ECCE as 4, and determining average number of resource elements occupied by each eREG; and

bl2. determining the average number of resource elements occupied by each eREG as the number of resource elements occupied by each eREG, when the average number of resource elements occupied by each eREG is an integer, and when the average number of resource elements occupied by each eREG is not an integer, implementing step b l2- l or bl2-2:

bl2-l . the network entity including a base station and an user equipment, and when the base station shares a third predefined rule with the user equipment, the base station and the user equipment determining the number of resource elements occupied by each eREG based on the third predefined rule;

bl2-2. the network entity including a base station and an user equipment, and when the base station does not share a third predefined rule with the user equipment, the base station determining the number of resource elements occupied by each eREG based on the third predefined rule, and sending a third message to the user equipment, the third message indicating number of resource elements occupied by each eREG occupied by the user equipment, and the user equipment receiving the third message from the base station and determining number of resource elements occupied by each eREG occupied by itself based on the third message.

9. A method according to claim 7, wherein the step b further includes: b21. determining that one ECCE occupies a third number of eREGs, and determining the average number of resource elements occupied by each eREG, when the determined number of resource elements occupied by ECCE is higher than or equal to a second threshold, and when the determined number of resource elements occupied by ECCE is lower than the second threshold, determining that one ECCE occupies a fourth number of eREGs, and determining the average number of resource elements occupied by each eREG; and

b22. determining the average number of resource elements occupied by each eREG as the number of resource elements occupied by each eREG, when the average number of resource elements occupied by each eREG is an integer, and when the average number of resource elements occupied by each eREG is not an integer, implementing step b22-l or b22-2:

b22-l . the network entity including a base station and an user equipment, and when the base station shares a fourth predefined rule with the user equipment, the base station and the user equipment determining the number of resource elements occupied by each eREG based on the fourth predefined rule;

b22-2. the network entity including a base station and an user equipment, and when the base station does not share a fourth predefined rule with the user equipment, the base station determining the number of resource elements occupied by each eREG based on the fourth predefined rule, and sending a fourth message to the user equipment, the fourth message indicating number of resource elements occupied by each eREG occupied by the user equipment, and the user equipment receiving the fourth message from the base station and determining number of resource elements occupied by each eREG occupied by itself based on the fourth message.

10. A method according to claim 8 or 9, wherein the third predefined rule and/or the fourth predefined rule includes minimizing difference between the numbers of resource elements occupied by each eREG.

11. A method according to claim 9, wherein the third number of eREGs is 4, and the fourth number of eREGs is 2.

12. A method according to claim 9, wherein the second threshold is 16.