Method and apparatus for managing contention window in wireless communication system
A base station is provided. The base station transmits multiple data in a first subframe, receives response signals corresponding to the multiple data, determines a ratio of negative acknowledge (NACK) signals to the response signals, and adjusts or maintains a contention window based on the determined ratio. The present disclosure relates to communication schemes for combining 5th-generation (5G) communication systems with internet of things (IoT) technology to support higher data transmission rate as post-4th-generation (post-4G) systems and systems for the same. The present disclosure may be used in intelligent services (e.g., smart home, smart building, smart city, smart car, or connected car, health-care, digital education, retail business, security and safety-related services, etc.) based on the 5G communication technology and IoT-related techniques.
1. A method for managing a contention window in a wireless communication system, the method comprising:
transmitting one or more data in a reference duration within a channel occupancy interval for a latest downlink transmission for which reception result feedback is available;
obtaining a reception result corresponding to the one or more data;
adjusting or maintaining the contention window based on at least one acknowledge (ACK) signal included in the reception result; and
sensing a channel based on the adjusted or the maintained contention window,
wherein the reference duration is a duration starting from a beginning of the channel occupancy interval until an end of first transmission time interval where the one or more data is transmitted over all resources allocated for the one or more data.
2. The method of claim 1 , wherein the adjusting or maintaining of the contention window comprising:
determining at least one of a number of ACK signal included in the reception result or a ratio of the at least one ACK signal in the reception result, and
setting the contention window based on the at least one of the number of ACK signal included in the reception result or the ratio of the at least one ACK signal in the reception result.
3. The method of claim 2 , wherein the setting of the contention window comprising:
setting the contention window to an initial value, if the number of ACK signal is a predetermined number or more, or if the ratio of the at least one ACK signal is a predetermined ratio or more,
wherein the initial value is a minimum value of predetermined contention window candidate values.
4. The method of claim 2 , wherein the setting of the contention window comprising:
increasing the contention window, if the number of ACK signal is less than a predetermined number or if the ratio of the at least one ACK signal is less than a predetermined ratio.
5. The method of claim 4 , wherein the increasing of the contention window comprising:
setting the contention window with a value larger than a currently set contention window value among predetermined contention window candidate values.
6. The method of claim 2 , wherein the determining of the at least one of a number of ACK signal included in the reception result or the ratio of the at least one ACK signal includes, upon success to detect a response signal for each of the one or more data, counting an ACK signal corresponding to corresponding data.
7. The method of claim 1 , further comprising:
setting the contention window to an initial value,
wherein the initial value is a minimum value of predetermined contention window candidate values.
8. The method of claim 1 , wherein the sensing of the channel comprising:
setting a value within the adjusted or the maintained contention window as a counter value;
sensing the channel during a first sensing interval to determine whether the sensed channel is idle;
if the channel is idle, reducing the counter value and transmitting data in a second transmission time interval using the channel based on the counter value; and
if the channel is not idle, sensing the channel during a second sensing interval.
9. The method of claim 8 , further comprising:
if the counter value is larger than a predetermined value, reducing the counter value by a designated value.
10. The method of claim 1 , wherein transmission time interval is a slot.
11. An apparatus for managing a contention window in a wireless communication system, the apparatus comprising:
a transmitter configured to transmit one or more data in a reference duration within a channel occupancy interval for a latest downlink transmission for which reception result feedback is available; and
at least one processor configured to:
obtain a reception result corresponding to the one or more data,
adjust or maintain the contention window based on at least one acknowledge (ACK) signal included in the reception result, and
sense a channel based on the adjusted or the maintained contention window,
wherein the reference duration is a duration starting from a beginning of the channel occupancy interval until an end of first transmission time interval where the one or more data is transmitted over all resources allocated for the one or more data.
12. The apparatus of claim 11 ,
wherein the at least one processor is further configured to:
determine at least one of a number of ACK signal included in the reception result or a ratio of the at least one ACK signal in the reception result, and
set the contention window based on the at least one of the number of ACK signal included in the reception result or the ratio of the at least one ACK signal in the reception result.
13. The apparatus of claim 12 , wherein the at least one processor is further configured to:
set the contention window to an initial value, if the number of ACK signal is a predetermined number or more, or if the ratio of the at least one ACK signal is a predetermined ratio or more,
wherein the initial value is a minimum value of predetermined contention window candidate values.
14. The apparatus of claim 12 , wherein the at least one processor is further configured to:
increase the contention window, if the number of ACK signal is less than a predetermined number or if the ratio of the at least one ACK signal is less than a predetermined ratio.
15. The apparatus of claim 14 , wherein the at least one processor is further configured to:
set the contention window with a value larger than a currently set contention window value among predetermined contention window candidate values.
16. The apparatus of claim 12 , wherein the at least one processor is further configured to:
upon success to detect a response signal for each of the one or more data, count an ACK signal corresponding to corresponding data.
17. The apparatus of claim 11 , wherein the at least one processor is further configured to:
set the contention window to an initial value,
wherein the initial value is a minimum value of predetermined contention window candidate values.
18. The apparatus of claim 11 , wherein the at least one processor is further configured to:
set a value within the adjusted or the maintained contention window as a counter value;
sense the channel during a first sensing interval to determine whether the sensed channel is idle;
if the channel is idle, reduce the counter value and control a transceiver to transmit data in a second transmission time interval using the channel based on the counter value; and
if the channel is not idle, sense the channel during a second sensing interval.
19. The apparatus of claim 18 , wherein the at least one processor is further configured to:
if the counter value is larger than a predetermined value, reduce the counter value by a designated value.
20. The apparatus of claim 11 , wherein transmission time interval is a slot.