Method for transmitting signal on basis of clear channel assessment in unlicensed band channel, and mobile communication system
Disclosed is a 5G or pre-5G communication system for supporting a data transmission rate higher than that of a 4G communication system such as LTE. Disclosed are: a method for transmitting a signal in an unlicensed band channel on the basis of a counter reduction in the unlicensed band channel of a mobile communication system and a clear channel assessment (CCA) of the channel; and a mobile communication system, and according to an embodiment of the present disclosure, the method for transmitting a signal in an unlicensed band channel on the basis of a counter reduction in the unlicensed band channel of a mobile communication system and a clear channel assessment (CCA) of the channel comprises the steps of: reducing the counter and performing a CCA for the channel, during a first period of transmitting a discovery signal and data; storing the reduced counter when a second period of transmitting only the discovery signal without the data is started; reducing the counter by using the stored counter and performing the CCA for the channel when a third period of transmitting the discovery signal and the data is started; and transmitting the discovery signal or the data on the channel on the basis of the counter value.
1. A method for transmitting a signal on a channel of a wireless communication system, the method comprising:
maintaining, by an electronic device, a counter for a first duration in which a discovery signal is transmitted but data is not transmitted;
decreasing, by the electronic device, the maintained counter and sensing the channel for a second duration; and
transmitting, by the electronic device, data on the channel if a value of the decreased counter is zero and the channel for the second duration is sensed to be idle.
2. The method of claim 1 , further comprising decreasing, by the electronic device, the counter and sensing the channel for a third duration before maintaining the counter for the first duration.
3. The method of claim 1 , wherein the counter is randomly set within a size of a contention window (Q) and the counter is zero or more than zero.
4. The method of claim 2 , wherein thresholds in listen before talk (LBT) parameters are differently set for the third duration and the first duration.
5. The method of claim 3 , wherein Q is set between a minimum value and a maximum value for a contention window (CW).
6. The method of claim 5 , wherein the minimum value or the maximum value for the CW are differently set for the third duration and the first duration.
7. The method of claim 1 , wherein if the channel for the second duration is sensed to be idle, the counter is decreased by one.
8. The method of claim 2 , wherein the third duration is less than 1 ms.
9. A wireless communication system for transmitting a signal on a channel, the wireless communication system comprising:
at least one transceiver; and
at least one processor configured to:
maintain a counter for a first duration in which a discovery signal is transmitted but data is not transmitted,
decrease the maintained counter and sense the channel for a second period, and
transmit data on the channel if a value of the decreased counter is zero and the channel for the second duration is sensed to be idle.
10. The wireless communication system of claim 9 , wherein the at least one processor is further configured to decrease the counter and sense the channel for a third duration before maintaining the counter for the first duration.
11. The wireless communication system of claim 9 , wherein the counter is randomly set within a size of a contention window (Q) and the counter is zero or more than zero.
12. The wireless communication system of claim 10 , wherein thresholds in listen before talk (LBT) parameters are differently set for the third duration and the first duration.
13. The wireless communication system of claim 11 , wherein Q is set between a minimum value and a maximum value for a contention window (CW).
14. The wireless communication system of claim 13 , wherein the minimum value or the maximum value for the CW are differently set for the third duration and the first duration.
15. The wireless communication system of claim 9 , wherein if the channel for the second duration is sensed to be idle, the counter is decreased by one.
16. The wireless communication system of claim 10 , wherein the third duration is less than 1 ms.