Method for transmitting synchronization signal and base station, and method for receiving synchronization signal and user equipment
N synchronization signals (where, N is an integer greater than 1) may be transmitted in a first subframe. M synchronization signals among the N synchronization signals (where, M is an integer satisfying M<N) may be turned off. The remaining N−M synchronization signals except the M synchronization signals may be transmitted in a second subframe. Each of the first subframe and the second subframe may comprise a plurality of time symbol sets, each including one or more time symbols in the time domain. The N synchronization signals may be transmitted in N time symbol sets among the plurality of time symbol sets of the first subframe, respectively. The N−M synchronization signals may be transmitted in N−M time symbol sets among the plurality of time symbol sets of the second subframe, respectively.
1. A method of transmitting a synchronization signal by a base station (BS), the method comprising:
transmitting N synchronization signal sets in a first subframe, where N is an integer larger than 1,
wherein each of the N synchronization signal sets is related to one of N different transmission beam directions; and
turning off M synchronization signal sets among the N synchronization signal sets and transmitting the remaining N−M synchronization signal sets in a second subframe, where M is an integer smaller than N,
wherein each of the N−M synchronization signal sets is related to one of N−M transmission beam directions,
wherein each of the first and second subframes includes a plurality of time symbol sets, each of which includes one or more time symbols in a time domain,
wherein the N synchronization signal sets are respectively transmitted in N time symbol sets among the plurality of time symbol sets in the first subframe,
wherein the N−M synchronization signal sets are respectively transmitted in N−M time symbol sets among the plurality of time symbol sets in the second subframe, and
wherein each of synchronization signal sets includes at least one of a primary synchronization signal (PSS) or a secondary synchronization signal (SSS).
2. The method according to claim 1 , wherein the N time symbol sets are consecutive, and wherein the N−M time symbol sets are consecutive.
3. The method according to claim 2 , wherein the N−M time symbol sets are composed of symbols at the start of the second subframe or symbols at the end of the second subframe.
4. The method according to claim 1 , comprising:
transmitting either the N synchronization signal sets or the N−M synchronization signal sets in each of a plurality of subframes for synchronization signal transmission,
wherein the plurality of subframes for synchronization signal transmission occur on a first periodicity,
wherein the first and second subframes are included in the subframes for the synchronization signal transmission.
5. The method according to claim 4 , comprising:
transmitting the M synchronization signal sets with a second periodicity longer than the first periodicity after the first subframe; and
based on a random access preamble being received on a random access channel resource associated with a first synchronization signal set among the M synchronization signal sets, turning on the first synchronization signal set and transmitting the N−M synchronization signal sets and the first synchronization signal set in N−M+1 time symbol sets with the first periodicity,
wherein the N−M+1 time symbol sets are consecutive.
6. The method according to claim 1 , further comprising:
transmitting information indicating the second subframe where the M synchronization signal sets are off.
7. The method according to claim 1 , further comprising:
transmitting information indicating that some of the N synchronization signal sets are off.
8. A base station (BS) for transmitting a synchronization signal, the BS comprising:
a radio frequency (RF) unit including a transceiver; and
a processor configured to control the RF unit, the processor configured to:
control the RF unit to transmit N synchronization signal sets in a first subframe, where N is an integer greater than 1,
wherein each of the N synchronization signal sets is related to one of N different transmission beam directions; and
control the RF unit to turn off M synchronization signal sets among the N synchronization signal sets and transmit the remaining N M synchronization signal sets in a second subframe, where M is an integer smaller than N,
wherein each of the N−M synchronization signal sets is related to one of N−M transmission beam directions,
wherein each of the first and second subframes includes a plurality of time symbol sets, each of which includes one or more time symbols in a time domain,
wherein the N synchronization signal sets are respectively transmitted in N time symbol sets among the plurality of time symbol sets in the first subframe,
wherein the N−M synchronization signal sets are respectively transmitted in N−M time symbol sets among the plurality of time symbol sets in the second subframe, and
wherein each of synchronization signal sets includes at least one of a primary synchronization signal (PSS) or a secondary synchronization signal (SSS).
9. The BS according to claim 8 , wherein the N time symbol sets are consecutive, and wherein the N−M time symbol sets are consecutive.
10. The BS according to claim 9 , wherein the N−M time symbol sets are composed of symbols at the start of the second subframe or symbols at the end of the second subframe.
11. The BS according to claim 8 ,
wherein the processor is configured to control the RF unit to transmit either the N synchronization signal sets or the N−M synchronization signal sets in each of a plurality of subframes for synchronization signal transmission,
wherein the plurality of subframes for synchronization signal transmission occur on a first periodicity, and
wherein the first and second subframes are included in the subframes for the synchronization signal transmission.
12. The BS according to claim 11 , wherein the processor is configured to:
control the RF unit to transmit the M synchronization signal sets with a second periodicity longer than the first periodicity after the first subframe; and
based on a random access preamble being received on a random access channel resource associated with a first synchronization signal set among the M synchronization signal sets, control the RF unit to turn on the first synchronization signal and transmit the N−M synchronization signal sets and the first synchronization signal set in N−M+1 time symbol sets with the first periodicity, and
wherein the N−M+1 time symbol sets are consecutive.
13. The BS according to claim 8 , wherein the processor is configured to control the RF unit to transmit information indicating the second subframe where the M synchronization signal sets are off.
14. The BS according to claim 8 , wherein the processor is configured to control the RF unit to transmit information indicating that some of the N synchronization signal sets are off.
15. A method for receiving a synchronization signal by a user equipment (UE), the method comprising:
receiving at least one of N synchronization signal sets in a first subframe, where N is an integer larger than 1,
wherein each of the N synchronization signal sets is related to one of N different transmission beam directions; and
receiving at least one of N−M synchronization signal sets in a second subframe, where M is an integer smaller than N, and wherein M synchronization signal sets are turned off among the N synchronization signal sets,
wherein each of the N−M synchronization signal sets is related to one of N−M transmission beam directions,
wherein each of the first and second subframes includes a plurality of time symbol sets, each of which includes one or more time symbols in a time domain,
wherein the N synchronization signal sets are respectively transmitted in N time symbol sets among the plurality of time symbol sets in the first subframe,
wherein the N−M synchronization signal sets are respectively transmitted in N−M time symbol sets among the plurality of time symbol sets in the second subframe, and
wherein each of synchronization signal sets includes at least one of a primary synchronization signal (PSS) or a secondary synchronization signal (SSS).
16. A user equipment (UE) for receiving a synchronization signal, the UE comprising:
a radio frequency (RF) unit including a transceiver; and
a processor configured to control the RF unit, the processor configured to:
control the RF unit to receive at least one of N synchronization signal sets in a first subframe, where N is an integer larger than 1,
wherein each of the N synchronization signal sets is related to one of N different transmission beam directions; and
control the RF unit to receive at least one of N−M synchronization signal sets in a second subframe, where M is an integer smaller than N, and wherein M synchronization signal sets are turned off among the N synchronization signal sets,
wherein each of the N−M synchronization signal sets is related to one of N−M transmission beam directions,
wherein each of the first and second subframes includes a plurality of time symbol sets, each of which includes one or more time symbols in a time domain,
wherein the N synchronization signal sets are respectively transmitted in N time symbol sets among the plurality of time symbol sets in the first subframe,
wherein the N−M synchronization signal sets are respectively transmitted in N−M time symbol sets among the plurality of time symbol sets in the second subframe, and
wherein each of synchronization signal sets includes at least one of a primary synchronization signal (PSS) or a secondary synchronization signal (SSS).