Communication method and communication terminal under discontinuous reception mode

1. A communication method in a discontinuous reception mode of a mobile communication system, comprising:

obtaining, by a terminal, allocation information of a contention based uplink grant, wherein the terminal knows in advance a time when a base station allocates the contention based uplink grant;

starting a second timer, wherein the terminal is kept active during the operation of the second timer;

stopping the second timer when a preset third condition is met;

performing, by the terminal, a contention based transmission in which the terminal performs uplink transmission by using a resource that is allocated via the contention based uplink grant in a manner of contention without transmitting a scheduling request in advance;

starting a first timer after the contention based transmission, wherein the terminal is kept active during operation of the first timer; and

stopping the first timer when a preset first condition is met.

2. The communication method according to claim 1 , wherein the first condition comprises: the terminal receiving a dedicated uplink grant allocated by the base station or the terminal receiving acknowledgement information sent by the base station, or expiration of a predefined first time period, or reception of a stop instruction.

3. The communication method according to claim 1 , further comprising:

determining, by the terminal, whether a contention based retransmission needs to be performed;

performing the contention based retransmission by the terminal when the terminal determines that the contention based retransmission is needed;

restarting the first timer; and

stopping the first timer when a preset second condition is met.

4. The communication method according to claim 1 , wherein the third condition comprises: the terminal completing an uplink transmission in the contention based uplink grant, or expiration of a predefined second time period, or reception of a stop instruction.

5. The communication method according to claim 1 , further comprising:

determining, by the terminal, whether a contention based retransmission needs to be performed;

obtaining, by the terminal, allocation information of the contention based uplink grant again when the terminal determines that the contention based retransmission is needed;

restarting the second timer; and

stopping the second timer when a preset fourth condition is met.

6. The communication method according to claim 1 , wherein in the step of obtaining, by the terminal, allocation information of a contention based uplink grant, the terminal obtains the information about the time when the base station allocates the contention based uplink grant via a broadcast or a dedicated message sent by the base station.

7. The communication method according to claim 1 , wherein in the step of obtaining, by the terminal, allocation information of a contention based uplink grant, the information about the time when the base station allocates the contention based uplink grant is obtained by mapping a cell radio network temporary identifier of the terminal to the time for receiving the contention based uplink grant.

8. The communication method according to claim 1 , wherein the terminal performs a blind decoding on the allocation of the base station, so as to obtain the allocation information of the contention based uplink grant.

9. A communication terminal having a discontinuous reception mode, comprising a transmitter, a receiver and a controller, the controller comprises a first timer and a second timer, wherein

the receiver is configured to obtain allocation information of a contention based uplink grant;

the transmitter is configured to perform a contention based transmission in which the terminal performs uplink transmission by using a resource that is allocated via the contention based uplink grant in a manner of contention without transmitting a scheduling request in advance;

the first timer is configured to be started after the contention based transmission, and to be stopped when a preset first condition is met; the second timer is configured to be started after the allocation information is obtained by the receiver, and to be stopped when a preset third condition is met; and

the controller is configured to keep the terminal active during the operation of the first timer and to keep the terminal active during the operation of the second timer,

wherein when the terminal obtains the allocation information of the contention based uplink grant, the terminal knows in advance a time when a base station allocates the contention based uplink grant.

10. The communication terminal according to claim 9 , wherein the first condition comprises: the terminal receiving a dedicated uplink grant allocated by the base station or the terminal receiving acknowledgement information sent by the base station, or expiration of a predefined first time period, or reception of a stop instruction.

11. The communication terminal according to claim 9 , wherein

the transmitter is further configured to perform a contention based retransmission when the terminal determines that the contention based retransmission is needed;

the first timer is further configured to be restarted after the retransmission; wherein the first timer is stopped when a preset second condition is met.

12. The communication terminal according to claim 9 , wherein the third condition comprises: the terminal completing an uplink transmission in the contention based uplink grant, or expiration of a predefined second time period, or reception of a stop instruction.

13. The communication terminal according to claim 9 , wherein:

the receiver is further configured to obtain allocation information of the contention based uplink grant again when the terminal determines that the contention based retransmission is needed;

the second timer is further configured to be restarted when the allocation information is obtained by the receiver again;

wherein the second timer is stopped when a preset fourth condition is met.

14. The communication terminal according to claim 9 , wherein when the terminal obtains the allocation information of the contention based uplink grant, the terminal obtains the information about the time when the base station allocates the contention based uplink grant via a broadcast or a dedicated message sent by the base station.

15. The communication terminal according to claim 9 , wherein when the terminal obtains the allocation information of the contention based uplink grant, the information about the time when the base station allocates the contention based uplink grant is obtained by mapping a cell radio network temporary identifier of the terminal to the time for receiving the contention based uplink grant.

16. The communication terminal according to claim 9 , wherein the terminal performs a blind decoding on the allocation of the base station, so as to obtain the allocation information of the contention based uplink grant.