Method for transmitting a synchronization signal block (SSB) based on a fixed frame period (FFP) by a communication device in a wireless communication system and apparatus using the same
Provided is a synchronization signal block (SSB) transmission method performed by a communication device in a wireless communication system. The method is characterized in that: a time duration of a fixed frame period (FFP) is set for another communication device; and the SSB is periodically transmitted to the other communication device, wherein the SSB is periodically transmitted on each Nth FFP, said N being an integer greater than or equal to 1, and the transmission start time of the SSB is the first time resource included in each Nth FFP.
1. A method for transmitting a downlink signal by a first communication device in a wireless communication system, the method comprising:
setting a value of counter (N) as N init , where N init is a random number uniformly distributed between 0 and a value of contention window, wherein the value of contention window is based on a channel access priority class associated with a transmission of the first communication device;
sensing a channel for an additional sensing slot duration;
based on the additional sensing slot duration being idle, the N being larger than 0, and the first communication device choosing to decrement the counter, setting the N as N−1;
transmitting, to a second communication device, a downlink control signal through the channel after the N is zero;
configuring time duration of a Fixed Frame Period (FFP) for the second communication device; and
transmitting a Synchronization Signal Block (SSB) to the second communication device periodically,
wherein the FFP is a divisor of a period in which the SSB is transmitted,
wherein the SSB is transmitted periodically on every N-th FFP, and the N is an integer larger than or equal to 1, and
wherein a transmission start position of the SSB is a first time resource included in every N-th FFP.
2. The method of claim 1 , wherein a transmission period of the SSB is the same as a measurement period related to cell measurement.
3. The method of claim 2 , wherein the cell measurement is a measurement of a serving cell or a neighboring cell.
4. The method of claim 1 , wherein the first communication device transmits a downlink signal to the second communication device after the SSB transmission.
5. The method of claim 1 , wherein the FFP includes a channel occupancy time and an idle period, and
wherein the idle period includes an observation slot.
6. The method of claim 5 , wherein the first communication device transmits a downlink signal to the second communication device during the channel occupancy time.
7. The method of claim 5 , wherein the first communication device performs a Clear Channel Assessment (CCA) operation in the observation slot.
8. The method of claim 5 , wherein time duration of the FFP configured by the first communication device is the same for each FFP.
9. The method of claim 1 , wherein the first communication device transmits a signal related to random access to the second communication device at the same period as the transmission period of the SSB.
10. The method of claim 1 , wherein the SSB is transmitted on an unlicensed band.
11. The method of claim 1 , wherein the first communication device is a base station, and the second communication device is a UE.
12. A communication device, comprising:
a transceiver transmitting and receiving a radio signal; and
a processor operating by being combined with the transceiver, wherein the processor is configured to:
set a value of counter (N) as N init , where N init is a random number uniformly distributed between 0 and a value of contention window, wherein the value of contention window is based on a channel access priority class associated with a transmission of the communication device;
sense a channel for an additional sensing slot duration;
based on the additional sensing slot duration being idle, the N being larger than 0, and the communication device choosing to decrement the counter, set the N as N−1;
transmit, to a different communication device, a downlink control signal through the channel after the N is zero;
configure time duration of a Fixed Frame Period (FFP) for the different communication device; and
transmit a Synchronization Signal Block (SSB) to the different communication device periodically,
wherein the FFP is a divisor of a period in which the SSB is transmitted,
wherein the SSB is transmitted periodically on every N-th FFP, and the N is an integer larger than or equal to 1, and
wherein a transmission start position of the SSB is a first time resource included in every N-th FFP.
13. The communication device of claim 12 , wherein the communication device communicates with at least one of a mobile terminal, a network, and a self-driving vehicle other than the communication device.
14. The communication device of claim 12 , wherein the communication device is a base station, and the different communication device is a UE.