1. A method for switching a state of a secondary carrier, comprising:', 'receiving, by a terminal device, a Media Access Control (MAC) Control Element (CE)', 'sent by a network device; and', 'switching, by the terminal device according to the MAC CE, a first secondary carrier of', 'the terminal device from a first state to a second state, wherein the first state and the second', 'state are two different states among activated state, deactivated state, and dormant state.

2. The method according to claim 1, wherein the MAC CE is a first MAC CE or a second', 'MAC CE, wherein the first MAC CE is used for indicating to switch thefirst secondary carrier from the activated state or the dormant state to the deactivated state when a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a first value, and to switch the first secondary carrier from the deactivated state or the dormant state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE is a second value; and the second MAC CE is used for indicating to switch the first secondary carrier from the activated state or the deactivated state to the dormant state.

3. The method according to claim 1, wherein the MAC CE is a first MAC CE or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the dormant state to the deactivated state, when a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a first value;', 'switching the first secondary carrier from the deactivated state to the activated state, when the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE is a second value;', 'and wherein the second MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the deactivated state to the dormant state when a value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is a first value, and switching the first secondary carrier from the dormant state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value.

4. The method according to claim 1, wherein the MAC CE is a first MAC CE or a second', 'MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the deactivated state or the dormant state to the', 'activated state when a value of a bit corresponding to an index of thefirst secondary carrier in', 'the first MAC CE is a first value;', 'switching the first secondary carrier from the activated state to the deactivated state when', 'the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE', 'is a second value;', 'and wherein the second MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the deactivated state to the', 'dormant state when a value of a bit corresponding to an index of the first secondary carrier in', 'the second MAC CE is a first value, and switching the first secondary carrier from the dormant', 'state to the deactivated state when the value of the bit corresponding to the index of the first', 'secondary carrier in the second MAC CE is a second value.

5. The method according to claim 1, wherein the MAC CE is a first MAC CE or a second', 'MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the deactivated state to the activated state when', 'a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a', 'first value;', 'switching the first secondary carrier from the activated state to the deactivated state', 'when the value of the bit corresponding to the index of the first secondary carrier in the first', 'MAC CE is a second value;', 'and wherein the second MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state to the dormant state when a', 'value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is', 'a first value, and switching the first secondary carrier from the dormant state to the activated', 'state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value.

6. The method according to any one of claims 2 to 5, wherein a sub-header corresponding to the first MAC CE comprises a first logical channel identifier (LCID), and a sub-header corresponding to the second MAC CE comprises a second LCID, wherein the first LCID is different from the second LCID.

7. The method according to any one of claims 1 to 6, wherein the first state is the activated state, the second state is the dormant state, and the method further comprises:', 'starting or restarting, by the terminal device, a first timer when the first secondary carrier enters the dormant state from the activated state;', 'if the terminal device receives, within a duration of the first timer, a MAC CE for indicating the first secondary carrier to enter the activated state from the dormant state, switching, by the terminal device, the first secondary carrier from the dormant state to the activated state, and starting or restarting the first timer, or', 'switching, by the terminal device, the first secondary carrier from the dormant state to the deactivated state if the first timer expires.

8. The method according to claim 7, wherein starting or restarting, by the terminal device, the first timer, comprises:', 'restarting, by the terminal device, the first timer, if the first timer is a timer configured by the network device for the first secondary carrier in the activated state; or', 'starting, by the terminal device, the first timer, if the first timer is a timer configured by the network device for the first secondary carrier in the dormant state.

9. The method according to any one of claims 1 to 8, wherein the MAC CE comprises multiple bits corresponding one-to-one to multiple secondary carriers of the terminal device, wherein a quantity of the multiple secondary carriers is a quantity of aggregated carriers supported by a system

10. The method according to any one of claims 1 to 9, wherein when thefirst secondary carrier is configured by the network device for the terminal device, the first secondary carrier is in the dormant state by default

11. A method for switching a state of a secondary carrier, comprising:', 'starting or restarting, by a terminal device, a first timer, when a first secondary carrier of', 'the terminal device enters dormant state;', 'if the terminal device receives, within a duration of the first timer, a Medium Access', 'Control (MAC) Control Element (CE) which indicates the first secondary carrier to enter', 'activated state, switching, by the terminal device, the first secondary carrier from the dormant', 'state to the activated state, and starting or restarting the first timer, or', 'switching, by the terminal device, the first secondary carrier from the dormant state to', 'deactivated state if the first timer expires

12. The method according to claim 11, wherein starting or restarting, by the terminal', 'device, the first timer, comprises:', 'restarting, by the terminal device, the first timer, if the first timer is a timer configured by a network device for the first secondary carrier in the activated state; or', 'starting, by the terminal device, the first timer, if the first timer is a timer configured by a network device for the first secondary carrier in the dormant state

13. A method for switching a state of a secondary carrier, comprising:', 'sending, by a network device, a Media Access Control (MAC) Control Element (CE) to a terminal device, wherein the MAC CE is used for indicating to switch a first secondary carrier of the terminal device from a first state to a second state, and the first state and the second state are two different states among activated state, deactivated state, and dormant state.14. The method according to claim 13, wherein the MAC CE is a first MAC CE or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the dormant state to the deactivated state when a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a first value;', 'switching the first secondary carrier from the deactivated state or the dormant state to the activated state when the value of the bit corresponding to the index of thefirst secondary carrier in the first MAC CE is a second value; and wherein the second MAC CE is used for indicating to switch thefirst secondary carrier from the activated state or the deactivated state to the dormant state.15. The method according to claim 13, wherein the MAC CE is a first MAC CE or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the dormant state to the deactivated state when a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a first value;', 'switching the first secondary carrier from the deactivated state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE is a second value;', 'and wherein the second MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the deactivated state to the dormant state when a value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is a first value, and switching the first secondary carrier from the dormant state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value.16. The method according to claim 13, wherein the MAC CE is a first MAC CE or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the deactivated state or the dormant state to the activated state when a value of a bit corresponding to an index of thefirst secondary carrier in the first MAC CE is afirst value;', 'switching the first secondary carrier from the activated state to the deactivated state when the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE is a second value;', 'and wherein the second MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the deactivated state to the dormant state when a value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is a first value, and switching the first secondary carrier from the dormant state to the deactivated state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value.17. The method according to claim 13, wherein the MAC CE is a first MAC CE or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the deactivated state to the activated state when a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a first value;', 'switching the first secondary carrier from the activated state to the deactivated state when the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE is a second value;', 'and wherein the second MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state to the dormant state when a value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is a first value, and switching the first secondary carrier from the dormant state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value.18. The method according to any one of claims 13 to 17, wherein a sub-header corresponding to the first MAC CE comprises a first logical channel identifier (LCID), and a sub-header corresponding to the second MAC CE comprises a second LCID, wherein the first LCID is different from the second LCID.19. The method according to any one of claims 13 to 18, wherein the MAC CE comprises multiple bits corresponding one-to-one to multiple secondary carriers of the terminal device, wherein a quantity of the multiple secondary carriers is a quantity of aggregated carriers supported by a system.

20. The method according to any one of claims 13 to 19, wherein when configuring, by the network device, the first secondary carrier for the terminal device, the first secondary carrier is in the dormant state by default.

21. A terminal device, comprising: a receiving unit, configured to receive a Media Access Control (MAC) Control Element', '(CE) sent by a network device; and', 'a switching unit, which switches, according to the MAC CE, a first secondary carrier of', 'the terminal device from a first state to a second state, wherein the first state and the second', 'state are two different states among activated state, deactivated state, and dormant state.

22. The terminal device according to claim 21, wherein the MAC CE is a first MAC CE', 'or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the dormant state to the', 'deactivated state when a value of a bit corresponding to an index of the first secondary carrier', 'in the first MAC CE is a first value;', 'switching the first secondary carrier from the deactivated state or the dormant state to the', 'activated state when the value of the bit corresponding to the index of the first secondary carrier', 'in the first MAC CE is a second value;', 'and wherein the second MAC CE is used for indicating to switch thefirst secondary', 'carrier from the activated state or the deactivated state to the dormant state.

23. The terminal device according to claim 21, wherein the MAC CE is a first MAC CE', 'or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the dormant state to the', 'deactivated state when a value of a bit corresponding to an index of the first secondary carrier', 'in the first MAC CE is a first value;', 'switching the first secondary carrier from the deactivated state to the activated state when', 'the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE', 'is a second value;', 'and the second MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the deactivated state to the', 'dormant state when a value of a bit corresponding to an index of the first secondary carrier in', 'the second MAC CE is a first value, and switching the first secondary carrier from the dormant', 'state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value.

24. The terminal device according to claim 21, wherein the MAC CE is a first MAC CE', 'or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the deactivated state or the dormant state to the', 'activated state when a value of a bit corresponding to an index of thefirst secondary carrier in', 'the first MAC CE is a first value;', 'switching the first secondary carrier from the activated state to the deactivated state when', 'the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE', 'is a second value;', 'and wherein the second MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the deactivated state to the', 'dormant state when a value of a bit corresponding to an index of the first secondary carrier in', 'the second MAC CE is a first value, and switching the first secondary carrier from the dormant', 'state to the deactivated state when the value of the bit corresponding to the index of the first', 'secondary carrier in the second MAC CE is a second value.

25. The terminal device according to claim 21, wherein the MAC CE is a first MAC CE', 'or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the deactivated state to the activated state when', 'a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a', 'first value;', 'switching the first secondary carrier from the activated state to the deactivated state when', 'the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE', 'is a second value;', 'and wherein the second MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state to the dormant state when a', 'value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is', 'a first value, and switching the first secondary carrier from the dormant state to the activated', 'state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value.

26. The terminal device according to any one of claims 22 to 25, wherein a sub-header corresponding to the first MAC CE comprises a first logical channel identifier (LCID), and a sub-header corresponding to the second MAC CE comprises a second LCID, wherein the first LCID is different from the second LCID.

27. The terminal device according to any one of claims 21 to 26, wherein the first state is the activated state, the second state is the dormant state, and the terminal device further comprises:', 'a timing unit, configured to, when the first secondary carrier enters the dormant state from the activated state, start or restart a first timer; and', 'the switching unit is further configured to:', 'if the receiving unit receives, within a duration of the first timer, a MAC CE for indicating the first secondary carrier to enter the activated state from the dormant state, switch the first secondary carrier from the dormant state to the activated state, or', 'switch the first secondary carrier from the dormant state to the deactivated state if the first timer expires.

28. The terminal device according to claim 27, wherein the timing unit is specifically configured to:', 'restart the first timer, if the first timer is a timer configured by the network device for the first secondary carrier in the activated state; or', 'start the first timer, if the first timer is a timer configured by the network device for the first secondary carrier in the dormant state.

29. The terminal device according to any one of claims 21 to 28, wherein the MAC CE comprises multiple bits corresponding one-to-one to multiple secondary carriers of the terminal device, wherein a quantity of the multiple secondary carriers is a quantity of aggregated carriers supported by a system.

30. The terminal device according to any one of claims 21 to 29, wherein when the first secondary carrier is configured by the network device for the terminal device, the first secondary carrier is in the dormant state by default.

31. A terminal device, comprising:', 'a timing unit, configured to start or restart a first timer when afirst secondary carrier of the terminal device enters dormant state; and', 'a switching unit, configured to, if the terminal device receives, within a duration of the first timer, a Medium Access Control (MAC) Control Element (CE) which indicates the first secondary carrier to enter activated state, switch the first secondary carrier from the dormant state to the activated state, or', 'switch the first secondary carrier from the dormant state to deactivated state if the first timer expires.

32. The terminal device according to claim 31, wherein the timing unit is specifically configured to:', 'restart the first timer, if the first timer is a timer configured by a network device for the first secondary carrier in the activated state; or', 'start the first timer if the first timer is a timer configured by a network device for the first secondary carrier in the dormant state.

33. A network device, comprising:', 'a sending unit, configured to send a Media Access Control (MAC) Control Element (CE) to a terminal device, wherein the MAC CE is used for indicating to switch a first secondary carrier of the terminal device from a first state to a second state, and the first state and the second state are two different states among activated state, deactivated state, and dormant state.

34. The network device according to claim 33, wherein the MAC CE is a first MAC CE or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the dormant state to the deactivated state when a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a first value;', 'switching the first secondary carrier from the deactivated state or the dormant state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE is a second value; and wherein the second MAC CE is used for indicating to switch thefirst secondary carrier from the activated state or the deactivated state to the dormant state.

35. The network device according to claim 33, wherein the MAC CE is a first MAC CE or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the dormant state to the deactivated state when a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a first value,', 'switching the first secondary carrier from the deactivated state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE is a second value;', 'and the second MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the deactivated state to the dormant state when a value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is a first value, and switching the first secondary carrier from the dormant state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value.

36. The network device according to claim 33, wherein the MAC CE is a first MAC CE or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the deactivated state or the dormant state to the activated state when a value of a bit corresponding to an index of thefirst secondary carrier in the first MAC CE is afirst value;', 'switching the first secondary carrier from the activated state to the deactivated state when the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE is a second value;', 'and wherein the second MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state or the deactivated state to the dormant state when a value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is a first value, and switching the first secondary carrier from the dormant state to the deactivated state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value.

37. The network device according to claim 33, wherein the MAC CE is a first MAC CE or a second MAC CE, wherein the first MAC CE is used for indicating that:', 'switching the first secondary carrier from the deactivated state to the activated state when a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a first value;', 'switching the first secondary carrier from the activated state to the deactivated state when the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE is a second value;', 'and wherein the second MAC CE is used for indicating that:', 'switching the first secondary carrier from the activated state to the dormant state when a value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is a first value, and switching the first secondary carrier from the dormant state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value.

38. The network device according to any one of claims 33 to 37, wherein a sub-header corresponding to the first MAC CE comprises a first logical channel identifier (LCID), and a sub-header corresponding to the second MAC CE comprises a second LCID, wherein the first LCID is different from the second LCID.

39. The network device according to any one of claims 33 to 38, wherein the MAC CE comprises multiple bits corresponding one-to-one to multiple secondary carriers of the terminal device, wherein a quantity of the multiple secondary carriers is a quantity of aggregated carriers supported by a system.

40. The network device according to any one of claims 33 to 39, wherein when the network device configures the first secondary carrier for the terminal device, the first secondary carrier is in the dormant state by default.', 'FIG. 1', 'FIG. 2', 'FIG. 3', 'FIG. 4', 'FIG. 5', 'FIG. 6', 'FIG. 7', 'FIG. 8', 'FIG. 9', 'FIG. 10', 'FIG. 11', 'FIG. 12', 'FIG. 13', 'FIG. 14', 'FIG. 15', 'FIG. 16']