User equipment and data transmission method thereof

1. A method for data transmission, comprising:

detecting a scheduling assignment (SA) for other UEs within a sensing window which includes a plurality of time units (TUs);

selecting, based on the detected SA, a set of resources for data transmission;

determining, if the UE does not perform data transmission on one of the selected set of resources, whether a resource subsequent to the one resource in the selected set of resources is occupied based on the detected SA, a received power and a received energy on the resource only in a case where a number of consecutive resources, among the selected set of resources, on which the UE does not perform data transmission exceeds a predetermined threshold NR 2 , before transmitting data on a resource in the selected set of resources; and

transmitting the data on the resource in the selected set of resources if it is determined hat the resource is not occupied.

2. The method according to claim 1 , wherein the determining whether the resource is occupied comprises:

determining whether a Listen-Before-Talk (LBT) mechanism needs to be performed within a predetermined time period T; and

determining that the resource is not occupied, if it is determined that the LBT mechanism does not need to be performed.

3. The method according to claim 2 , wherein the predetermined time period T is obtained from:

a time period having a length of T from a beginning of a TU; or

a time period having a length of T in which a padding signal is transmitted before a TU.

4. The method according to claim 2 , wherein determining whether the LBT mechanism needs to be performed within the predetermined time period T comprises at least:

determining that the LBT mechanism does not need to be performed for data transmission on a resource R k,o ;

determining that the LBT mechanism does not need to be performed for data transmission on a resource R k,d , if the UE has performed data transmission on d consecutive resources before the resource R k,c where c<d<C;

determining that the LBT mechanism does not need to be performed for data transmission on the resource R k,d , if the UE has performed data transmission on D1 consecutive resources R k,c before the resource R k,d where d-D1≤c<d and D1≤d<C;

determining that the LBT mechanism does not need to be performed for data transmission on the resource R k,d if the UE has performed data transmission on min(D2, d) consecutive resources R k,c before the resource R k,d where max(d−D2,0)≤c<d<C;

determining that the LBT mechanism does not need to be performed for data transmission on the resource R k,d , if a number of resources R k,c , among D3 consecutive resources R k,c before the resource R k,d , on which the UE performs data transmission is no less than E1, where d−D3≤c<d and D3≤d<C;

determining that the LBT mechanism does not need to be performed for data transmission on the resource R k,d , if a number of resources R k,c among min(D4, d) consecutive resources R k,c before the resource R k,d , on which the UE performs data transmission is no less than E1, where max(d−D4,0)≤c<d<C;

determining that the LBT mechanism does not need to be performed, if the UE only performs a single transmission on the selected set of resources,

where R k,c represents the resource in the selected set of resources, k=0, 1, . . . , K−1, c=0, 1, . . . ,C−1, K is a number of times one piece of data is transmitted in a period, C is a number of periods for reserving the resource, and D1, D2, D3, D4 and E1 are threshold values.

5. The method according to claim 2 , wherein determining whether the LBT mechanism needs to be performed within the predetermined time period T comprises at least:

determining that the LBT mechanism needs to be performed for data transmission on a resource R k,o ;

determining that the LBT mechanism needs to be performed for data transmission on first D5 consecutive resources R k,c where c<D5;

determining that the LBT mechanism needs to be performed for data transmission on the resource R k,d , if the UE does not perform data transmission on at least one of D6 consecutive resources R k,d before the resource R k,d , where d−D6≤c<d and D6≤d<C;

determining that the LBT mechanism needs to be performed for data transmission on the resource R k,d , if the UE does not perform data transmission on at least one of min(D7, d) consecutive resources R k,c before the resource R k,d , where max(d−D7,0)≤c<d<C;

determining that the LBT mechanism needs to be performed for data transmission on the resource R k,d , if a number of resources R k,c , among D8 consecutive resources R k,c , before the resource R k,d , on which the UE does not perform data transmission is no less than 1 and a number of resources R k,c , among d consecutive resources R k,c before the resource R k,d , on which the UE does not perform data transmission is no less than E2, where d−D8≤c<d and D8≤d<C;

determining that the LBT mechanism needs to be performed for data transmission on the resource R k,d , if a number of resources R k,c among min(D9, d) consecutive resources R k,c before the resource R k,d , on which the UE does not perform data transmission is no less than 1 and a number of resources R k,c among d consecutive resources R k,c before the resource R k,d , on which the UE does not perform data transmission is no less than E3, where max(d−D9,0)≤c<d<C;

determining that the LBT mechanism needs to be performed for data transmission on the resource R k,d , if a number of resources R k,c , among D10 consecutive resources R k,c before the resource R k,d , on which the UE does not perform data transmission is no less than E4, where d−D10≤c<d and D10≤d<C;

determining that the LBT mechanism needs to be performed for data transmission on the resource R k,d , if a number of resources R k,c , among min(D11, d) consecutive resources R k,c before the resource R k,d , on which the UE does not perform data transmission is no less than E5, where max(d−D11,0)≤c<d<C;

determining that the LBT mechanism needs to be performed, if the UE only performs a single transmission on the selected set of resources,

where R k,c represents the resource in the selected set of resources, k=0, 1, . . . , K−1 c=0, 1, . . . , C−1, K is a number of times one piece of data is transmitted in a period, C is a number of periods for reserving the resource, and D5, D6, D7, D8, D9, D10, D11 and E2, E3, E4, E5 are threshold values.

6. The method according to claim 2 , further comprising:

determining that one of the selected resources is not occupied in a case where a channel energy does not exceed an energy threshold X Thresh , if it is determined that the LBT mechanism needs to be performed,

wherein the energy thresholds X Thresh used by the LBT mechanism are identical or different for different performing conditions.

7. The method according to claim 1 , wherein determining whether the resource is occupied comprises:

determining, if the UE does not perform data transmission on one of the selected set of resources, whether a resource subsequent to the one resource in the selected set of resources is occupied based on the detected SA, a received power and a received energy on the resource only in a case where a number of resources, among the selected set of resources, on which the UE does not perform data transmission exceeds a predetermined threshold NR 1 .

8. The method according to claim 1 , wherein a threshold of the received power for determining whether the resource subsequent to the one resource in the selected set of resources is occupied is different from a threshold of a received power for performing resource selection; and when the received energy exceeds its threshold, it is determined that the resource subsequent to the resource in the selected set of resources is occupied.

9. The method according to claim 4 , further comprising:

determining, if the UE does not perform data transmission on one of the selected set of resources, whether the resource subsequent to the one resource in the selected set of resources is occupied, in conjunction with the LBT operation and based on the detected SA, the received power and the received energy.

10. A user equipment (UE), comprising:

a detection unit configured to detect a scheduling assignment (SA) for other UEs within a sensing window which includes a plurality of time units (TUs);

a selection unit configured to select, based on the detected SA, a set of resources for data transmission;

a determination unit configured to determine, if the UE does not perform data transmission on one of the selected set of resources, whether a resource subsequent to the one resource in the selected set of resources is occupied based on the detected SA, a received power and a received energy on the resource only in a case where a number of consecutive resources, among the selected set of resources, on which the UE does not perform data transmission exceeds a predetermined threshold NR 2 , before transmitting data on a resource in the selected set of resources; and

a transceiver configured to transmit the data on the resource in the selected set of resources if the determination unit determines that the resource is not occupied.

11. The UE according to claim 10 , wherein the determination unit is configured to determine whether the resource is occupied by:

determining whether a Listen-Before-Talk (LBT) mechanism needs to be performed within a predetermined time period T; and

determining that the resource is not occupied, if it is determined that the LBT mechanism does not need to be performed.

12. The UE according to claim 11 , wherein the predetermined time period T is obtained from:

a time period having a length of T from a beginning of a TU; or

a time period having a length of T in which a padding signal is transmitted before a TU.

13. The UE according to claim 11 , wherein the determination unit is configured to determine whether the LBT mechanism needs to be performed within the predetermined time period T by at least:

determining that the LBT mechanism does not need to be performed for data transmission on a resource R k,o ;

determining that the LBT mechanism does not need to be performed for data transmission on a resource R k,d , if the UE has performed data transmission on d consecutive resources R k,c before the resource R k,d where c<d<C;

determining that the LBT mechanism does not need to be performed for data transmission on the resource R k,d , if the UE has performed data transmission on D1 consecutive resources R k,c before the resource R k,d , where d−D1≤c<d and D1≤d<C;

determining that the LBT mechanism does not need to be performed for data transmission on the resource R k,d , if the UE has performed data transmission on min(D2, d) consecutive resources R k,c before the resource R k,d , where max(d−D2,0)≤c<d<C;

determining that the LBT mechanism does not need to be performed for data transmission on the resource R k,d , if a number of resources R k,c , among D3 consecutive resources R k,c , before the resource R k,d , on which the UE performs data transmission is no less than E1, where d−D3≤c<d and D3≤d<C ;

determining that the LBT mechanism does not need to be performed for data transmission on the resource R k,d , if a number of resources R k,c ,among min(D4, d) consecutive resources R k,c before the resource R k,d , on which the UE performs data transmission is no less than E1, where max(d−D4,0)≤c<d<C;

determining that the LBT mechanism does not need to be performed, if the UE only performs a single transmission on the selected set of resources,

where R k,c represents the resource in the selected set of resources, k=0, 1, . . . , K−1 c=0, 1, . . . , C−1, K is a number of times one piece of data is transmitted in a period, C is a number of periods for reserving the resource, and D1, D2, D3, D4 and E1 are threshold values.

14. The UE according to claim 11 , wherein the determination unit is configured to determine whether the LBT mechanism needs to be performed within the predetermined time period T by at least:

determining that the LBT mechanism needs to be performed for data transmission on a resource R k,o ;

determining that the LBT mechanism needs to be performed for data transmission on first D5 consecutive resources R k,c where c<D5;

determining that the LBT mechanism needs to be performed for data transmission on the resource R k,d , if the UE does not perform data transmission on at least one of D6 consecutive resources R k,c before the resource R k,d , where d−D6≤c<d and D6≤d<C;

determining that the LBT mechanism needs to be performed for data transmission on the resource R k,d , if the UE does not perform data transmission on at least one of min(D7, d) consecutive resources R k,c before the resource R k,d , where max(d−D7,0)≤c<d<C;

determining that the LBT mechanism needs to be performed for data transmission on the resource R k,d , if a number of resources R k,c , among D8 consecutive resources R k,c , before the resource R k,d , on which the UE does not perform data transmission is no less than 1 and a number of resources R k,c , among d consecutive resources R k,c before the resource R k,d , on which the UE does not perform data transmission is no less than E2, where d−D8≥c<d and D8≥d<C;

determining that the LBT mechanism needs to be performed for data transmission on the resource R k,d , if a number of resources R k,c , among min(D9, d) consecutive resources R k,c before the resource R k,d , on which the UE does not perform data transmission is no less than 1 and a number of resources R k,c , among d consecutive resources R k,c before the resource R k,d , on which the UE does not perform data transmission is no less than E3, where max(d−D9,0)≤c<d<C;

determining that the LBT mechanism needs to be performed for data transmission on the resource R k,d , if a number of resources R k,c , among D10 consecutive resources R k,c before the resource R k,d , on which the UE does not perform data transmission is no less than E4, where d−D10≤c<d and D10≤d<C;

determining that the LBT mechanism needs to be performed for data transmission on the resource R k,d , if a number of resources R k,c , among min(D11, d) consecutive resources R k,c before the resource R k,d , on which the UE does not perform data transmission is no less than E5, where max(d−D11,0)≤c<d<C;

determining that the LBT mechanism needs to be performed, if the UE only performs a single transmission on the selected set of resources,

where R k,c represents the resource in the selected set of resources, k=0, 1, . . . , K−1 c=0, 1, . . . , C−1, K is a number of times one piece of data is transmitted in a period, C is a number of periods for reserving the resource, and D5, D6, D7, D8, D9, D10, D11 and E2, E3, E4, E5 are threshold values.