Method for cell discovery
View Patent ↗Disclosed is a method for cell discovery. In a network in which a macro cell overlaps at least one small cell, when the carrier frequency used by the macro cell is different from the carrier frequency used by the small cell, the small cell transmits a discovery signal using the carrier frequency used by the macro cell, or the small cell transmits a discovery signal using a carrier frequency of the small cell that is different from the carrier frequency used by the macro cell.
1. A cell discovery method performed in a terminal, the cell discovery method, comprising:
receiving, from a base station, a resource and sequence information including a virtual cell ID which is used for calculating a sequence for a channel state information-reference signal (CSI-RS) included in a discovery signal;
calculating the sequence for the CSI-RS included in the discovery signal using the virtual cell ID included in the resource and sequence information;
measuring the discovery signal using the calculated sequence; and
reporting the measurement result of the discovery signal to the base station,
wherein the sequence is calculated based on a following initialization equation:
c init =2 10 ·(7·( n s +1)+ I+ 1)·(2· N ID CSI +1)+2· N ID CSI +N CP ,
n s is a slot number in a frame, I is a symbol number in a slot, N ID CSI is the virtual cell ID, N cp is 0 when an extended cyclic prefix (CP) is used, and N cp is 1 when a normal CP is used.
2. The cell discovery method of claim 1 , wherein the sequence is calculated by a following sequence equation:
r
l
,
n
s
(
m
)
=
1
2
(
1
-
2
·
c
(
2
m
)
)
+
j
1
2
(
1
-
2
·
c
(
2
m
+
1
)
)
,
m
=
0
,
1
,
…
,
N
RB
max
,
DL
-
1
,
r 1,n s (m) is the sequence, N RB max,DL is a maximum number of downlink resource blocks (DL RBs), and c(2m) and c(2m+1) are calculated using the C init .
3. The cell discovery method of claim 1 , wherein the discovery signal is configured based on a single antenna port.
4. The cell discovery method of claim 1 , wherein the discovery signal is received through subframes for frame type 1 or 2.
5. The cell discovery method of claim 1 , wherein the discovery signal is received through two resource elements for respective resource blocks.
6. The cell discovery method of claim 1 , wherein the resource and sequence information indicates at least one of a transmission period of the discovery signal and resource elements to which the discovery signal is allocated.
7. The cell discovery method of claim 1 , wherein the discovery signal further includes a primary discovery signal (PDS) and a secondary discovery signal (SDS), the PDS is generated based on a primary synchronization signal (PSS), and the SDS is generated based on a secondary synchronization signal (SSS).
8. The cell discovery method of claim 1 , wherein the measuring of the discovery signal measures at least one of a received signal strength indicator (RSSI) of the discovery signal, a reference signal received power (RSRP) of the discovery signal, and a reference signal received quality (RSRQ) of the discovery signal.