Method for setting search region for downlink control channel in wireless communication system, and apparatus therefor
The present invention relates to a method for a terminal to receive an enhanced physical downlink control channel (EPDCCH) from a based station in a wireless communication system. In detail, the method includes the step of: receiving the EPDCCH by monitoring EPDCCH candidates consisting of one or more enhanced control channel elements (ECCEs) in at least one resource block set for EPDCCH, wherein the number of ECCEs forming each of the EPDCCH candidates corresponds to an aggregation level, and the period between the EPDCCH candidates for one carrier, which is a specific aggregation level, is determined by dividing the total number of ECCEs included in each of the one or more resource blocks by a corresponding aggregation level and the number of the EPDCCH candidates which are the specific aggregation level.
1. A method for receiving an EPDCCH (Enhanced Physical Downlink Control Channel) from a base station by a user equipment (UE) in a wireless communication system, the method comprising:
receiving the EPDCCH by monitoring EPDCCH candidates in at least one resource block set for the EPDCCH,
wherein a number of ECCEs (Enhanced Control Channel Elements) included in each of the EPDCCH candidates is an aggregation level; and
wherein an interval between each of the EPDCCH candidates for a first carrier at a specific aggregation level is determined based on a first value obtained by dividing a total number of ECCEs included in the at least one resource block set by a number of the EPDCCH candidates at the specific aggregation level.
2. The method of claim 1 , wherein the interval between each of the EPDCCH candidates for the first carrier at the specific aggregation level is determined by equation A:
⌊
N
ECCE
,
p
,
k
L
·
M
p
(
L
)
⌋
,
〈
Equation
A
〉
where N ECCE,p,k is a number of ECCEs included in a resource block set p of a subframe k, L is the specific aggregation level, and M p (L) is a number of EPDCCH candidates at the specific aggregation level.
3. The method of claim 1 , wherein a position of the EPDCCH candidate #m for a second carrier at the specific aggregation level is determined by applying an offset value into a position of the EPDCCH candidate #m for the first carrier at the specific aggregation level.
4. The method of claim 3 , wherein the offset value is determined based on a carrier index n CI of the second carrier.
5. The method of claim 1 , wherein a position of the EPDCCH candidate #m at the specific aggregation level L is determined by equation B:
L
{
(
Y
p
,
k
+
⌊
m
·
N
ECCE
,
p
,
k
L
·
M
p
(
L
)
⌋
+
b
)
mod
⌊
N
ECCE
,
p
,
k
/
L
⌋
}
+
i
〈
Equation
B
〉
where i=0, . . . , L−1, Y p,k is a variable, N ECCE,p,k is a number of ECCEs included in a resource block set p of a subframe k, M p (L) is a number of EPDCCH candidates at the specific aggregation level, and b indicates an offset value determined based on a carrier index.
6. The method of claim 5 , wherein:
if the EPDCCH candidate # m is for the first carrier, the offset value is 0, and
if the EPDCCH candidate # m is for the second carrier, the offset value is configured as the carrier index n CI of the second carrier.
7. The method of claim 6 , wherein the variable Y p,k is defined by equation C:
Y p,k =( A·Y p,k-1 )mod D, <Equation C>
where A=39827, D=65537, k=└n s /2┘, n s indicates a slot index in one radio frame, Y −1 =n RNTI ≠0 and n RNTI indicates a UE ID.
8. The method of claim 1 , wherein the interval between each of the EPDCCH candidates for the first carrier at the specific aggregation level is determined based on a second value obtained by dividing the first value by the specific aggregation level.
9. A user equipment (UE) in a wireless communication system, the UE comprising:
a radio frequency (RF) module; and
a processor operably coupled with the RF module and configured to:
receive, via the RF module, an EPDCCH (Enhanced Physical Downlink Control Channel) by monitoring EPDCCH candidates in at least one resource block set for the EPDCCH,
wherein a number of ECCEs (Enhanced Control Channel Elements) included in each of the EPDCCH candidates corresponds to an aggregation level, and
wherein an interval between each of the EPDCCH candidates for a first carrier at a specific aggregation level is determined based on a first value obtained by dividing a total number of ECCEs included in the at least one resource block set by a number of the EPDCCH candidates at the specific aggregation level.
10. The UE of claim 9 , wherein the interval between each of the EPDCCH candidates for the one carrier at the specific aggregation level is determined by equation A:
N
ECCE
,
p
,
k
L
·
M
p
(
L
)
〈
Equation
A
〉
where N ECCE,p,k is a number of ECCEs included in a resource block set p of a subframe k, L is the specific aggregation level, and M p (L) is a number of EPDCCH candidates at the specific aggregation level.
11. The UE of claim 9 , wherein the processor determines a position of an EPDCCH candidate #m for a second carrier at the specific aggregation level by applying an offset value to a position of the EPDCCH candidate #m for the second carrier at the specific aggregation level.
12. The UE of claim 11 , wherein the offset value is determined based on a carrier index n CI of the second carrier.
13. The UE of claim 12 , wherein the processor determines a position of the EPDCCH candidate #m at the specific aggregation level L by equation B:
L
{
(
Y
p
,
k
+
⌊
m
·
N
ECCE
,
p
,
k
L
·
M
p
(
L
)
⌋
+
b
)
mod
⌊
N
ECCE
,
p
,
k
/
L
⌋
}
+
i
(
where
,
i
=
0
,
…
,
L
-
1
)
L
{
(
Y
p
,
k
+
⌊
m
·
N
ECCE
,
p
,
k
L
·
M
p
(
L
)
⌋
+
b
)
mod
⌊
N
ECCE
,
p
,
k
/
L
⌋
}
+
i
,
〈
Equation
B
〉
where i=0, . . . , L−1, Y p,k is a variable, N ECCE,p,k is a number of ECCEs included in a resource block set p of a subframe k, M p (L) is a number of EPDCCH candidates at the specific aggregation level, and b indicates an offset value determined based on a carrier index.
14. The UE of claim 13 , wherein:
if the EPDCCH candidate # m is for the first carrier, the offset value is 0, and
if the EPDCCH candidate # m is for the second carrier, the offset value is configured as the carrier index n CI of the second carrier.
15. The UE of claim 14 , wherein the variable Y p,k is defined by equation C:
Y p,k =( A·Y p,k-1 )mod D, <Equation C>
where A=39827, D=65537, k=└n s /2┘, n s indicates a slot index in one radio frame, Y −1 =n RNTI ≠0 and n RNTI indicates a UE ID.
16. The UE of claim 9 , wherein the interval between each of the EPDCCH candidates for the first carrier at the specific aggregation level is determined based on a second value obtained by dividing the first value by the specific aggregation level.