Method for transmitting discovery message in wireless communication system and apparatus for same
A method for transmitting a discovery message in a wireless communication system supporting device-to-device (D2D) direct communication, the method performed by the device, includes: discovering a D2D synchronization signal; classifying one or more macros by using the strength of the discovered D2D synchronization signal; receiving macro resource allocation information from a base station of the classified macro; sensing a macro resource of the classified macro based on the received macro resource allocation information; determining a macro resource for selecting a discovery resource through the sensing result; determining a discovery resource for transmitting a discovery message in the determined macro resource; and transmitting the discovery message through the determined discovery resource.
1. A method, performed by a terminal, for transmitting a discovery signal in a wireless communication system supporting device-to-device (D2D) direct communication, the method comprising:
discovering a D2D synchronization signal;
classifying one or more macro base stations by using a strength of the discovered D2D synchronization signal;
receiving macro resource allocation information from the classified macro base stations;
sensing a macro resource of the classified macro base stations based on the received macro resource allocation information;
selecting the macro resource as a discovery resource based on the sensing of the macro resource;
transmitting the discovery signal through the discovery resource,
wherein the macro resource is selected based on a maximum summation of power values measured in the macro resource and a value indicating the number of other terminals which are anticipated to successfully receive the discovery signal.
2. The method of claim 1 , wherein:
the classifying of the one or more macro base stations includes:
measuring strengths of D2D synchronization signals transmitted from multiple macro base stations;
comparing the measured strengths of the D2D synchronization signals and a predetermined threshold; and
classifying one or more macro base stations for transmitting D2D synchronization signals having strengths greater than the threshold.
3. The method of claim 1 , wherein:
the macro resource is based on an equation given below:
m
^
=
argmax
m
∈
M
α
∑
k
=
1
K
b
k
m
subject
to
N
m
o
-
N
m
<
ϵ
wherein b k m represents a power value measured in a macro resource of an m-th macro base station and N m represents a value indicating the number of other terminals which are anticipated to successfully receive discovery signals thereof when the m-th macro base station is selected.
4. The method of claim 1 , further comprising:
receiving another discovery signal transmitted from another terminal through a resource other than the determined discovery resource.
5. The method of claim 4 , further comprising:
reselecting a macro resource as the discovery resource based on the received discovery signal of the another terminal.
6. The method of claim 5 , further comprising:
the macro resource is reselected based on an equation given below:
m
^
=
argmax
m
∈
M
α
∑
k
=
1
K
b
k
m
subject
to
N
m
o
-
N
m
<
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wherein b k m represents a measured power value of a discovery signal received in the m-th macro base station and N m represents a value indicating the number of other terminals which are anticipated to successfully receive discovery signals thereof when the m-th macro base station is selected.
7. A terminal for transmitting a discovery signal in a wireless communication system supporting device-to-device (D2D) direct communication, the terminal comprising:
a radio frequency (RF) unit for transmitting and receiving a radio signal; and
a processor functionally connected with the RF unit,
wherein the processor:
discovers a D2D synchronization signal;
classifies one or more macro base stations by using a strength of the discovered D2D synchronization signal;
controls the RF unit to receive macro resource allocation information from the classified macro base stations;
senses a macro resource of the classified macro base stations based on the received macro resource allocation information;
selects the macro resource as a discovery resource based on the sensing of the macro resource;
controls the RF unit to transmit the discovery signal through the discovery resource,
wherein the processor selects the macro resource based on a maximum summation of power values measured in the macro resource and a value indicating the number of other terminals which are anticipated to successfully receive the discovery signal.
8. The terminal of claim 7 , wherein the processor measures strengths of D2D synchronization signals transmitted from multiple macro base stations;
compares the measured strengths of the D2D synchronization signals and a predetermined threshold; and
classifies one or more macro base stations for transmitting D2D synchronization signals having strengths greater than the threshold.
9. The terminal of claim 7 , wherein the processor controls the RF unit to receive the discover signal transmitted from another terminal through a resource other than the determined discovery resource.
10. The terminal of claim 9 , wherein the processor reselects a macro resource as the discovery resource based on the received discovery signal of another terminal.