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 and according to the MAC CE, a first secondary carrier of the terminal device from a first state to a second state, wherein one of the first state and the second state is a dormant state, and the other is an activated state or a deactivated state, wherein the MAC CE is a first MAC CE or a second MAC CE, and wherein each of the first and second MAC CEs is configured to control three state changes among the dormant state, the activated state, and the deactivated state;
wherein, when the MAC CE is the first MAC CE,
the first MAC CE is used for indicating:
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, and
wherein the first MAC CE is further used for indicating:
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,

wherein, when the MAC CE is the second MAC CE, the second MAC CE indicates:
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; and

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.', 'receiving, by a terminal device, a Media Access Control (MAC) Control Element (CE) sent by a network device; and', 'switching, by the terminal device and according to the MAC CE, a first secondary carrier of the terminal device from a first state to a second state, wherein one of the first state and the second state is a dormant state, and the other is an activated state or a deactivated state, wherein the MAC CE is a first MAC CE or a second MAC CE, and wherein each of the first and second MAC CEs is configured to control three state changes among the dormant state, the activated state, and the deactivated state;', 'wherein, when the MAC CE is the first MAC CE,', 'the first MAC CE is used for indicating:
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, and
wherein the first MAC CE is further used for indicating:
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,', '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, and', 'wherein the first MAC CE is further used for indicating:', '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,', 'wherein, when the MAC CE is the second MAC CE, the second MAC CE indicates:
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; and', '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; and', '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.

2. The method according to claim 1, wherein the second MAC CE comprises:
a R domain bit and C domain bits, wherein the R domain bit is a reserved bit, value of which is 0, and wherein each of the C domain bits corresponds to an index of a secondary carrier.', 'a R domain bit and C domain bits, wherein the R domain bit is a reserved bit, value of which is 0, and wherein each of the C domain bits corresponds to an index of a secondary carrier.

3. The method according to claim 2, wherein a length of the second MAC CE is 8 bits or 32 bits.

4. The method according to claim 1, wherein a first value in the second MAC CE is1.

5. The method according to claim 1, wherein a first value in the first MAC CE is 0.

6. The method according to claim 1, 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; and
switching, by the terminal device, the first secondary carrier from the dormant state to the deactivated state when the first timer expires.', 'starting or restarting, by the terminal device, a first timer when the first secondary carrier enters the dormant state from the activated state; and', 'switching, by the terminal device, the first secondary carrier from the dormant state to the deactivated state when the first timer expires.

7. 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, one of the first state and the second state is a dormant state, and the other is an activated state or a deactivated state, wherein the MAC CE is a first MAC CE or a second MAC CE, and wherein each of the first and second MAC CEs is configured to control three state changes among the dormant state, the activated state, and the deactivated state;
wherein, when the MAC CE is the first MAC CE,
the first MAC CE is used for indicating 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, and
wherein the first MAC CE is further used for indicating 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,
wherein, when the MAC CE is the second MAC CE, the second MAC CE indicates:
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; and

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.', '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, one of the first state and the second state is a dormant state, and the other is an activated state or a deactivated state, wherein the MAC CE is a first MAC CE or a second MAC CE, and wherein each of the first and second MAC CEs is configured to control three state changes among the dormant state, the activated state, and the deactivated state;', 'wherein, when the MAC CE is the first MAC CE,', 'the first MAC CE is used for indicating 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, and', 'wherein the first MAC CE is further used for indicating 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,', 'wherein, when the MAC CE is the second MAC CE, the second MAC CE indicates:
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; and', '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; and', '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.', '8. The method according to claim 7, wherein the second MAC CE comprises:
a R domain bit and C domain bits, wherein the R domain bit is a reserved bit, value of which is 0, and wherein each of the C domain bits corresponds to an index of a secondary carrier.', 'a R domain bit and C domain bits, wherein the R domain bit is a reserved bit, value of which is 0, and wherein each of the C domain bits corresponds to an index of a secondary carrier.', '9. The method according to claim 8, wherein a length of the second MAC CE is 8 bits or 32 bits.', '10. The method according to claim 7, wherein a first value in the second MAC CE is1.', '11. The method according to claim 7, wherein a first value in the first MAC CE is 0.', '12. The method according to claim 7, 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.', '13. The method according to claim 7, 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.', '14. A terminal device, comprising a memory, a processor, an input interface and an output interface, the memory, the processor, the input interface and the output interface are connected through a bus system, the memory is configured to store instructions, and the processor is configured to execute the instructions stored in the memory to:
receive a Media Access Control (MAC) Control Element (CE) sent by a network device; and
switch, according to the MAC CE, a first secondary carrier of the terminal device from a first state to a second state, wherein one of the first state and the second state is a dormant state, and the other is an activated state or a deactivated state, wherein the MAC CE is a first MAC CE or a second MAC CE, and wherein each of the first and second MAC CEs is configured to control three state changes among the dormant state, the activated state, and the deactivated state;
wherein, when the MAC CE is the first MAC CE,
the first MAC CE is used for indicating:
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, and
wherein the first MAC CE is further used for indicating: 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,

wherein, when the MAC CE is the second MAC CE, the second MAC CE indicates:
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; and

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.', 'receive a Media Access Control (MAC) Control Element (CE) sent by a network device; and', 'switch, according to the MAC CE, a first secondary carrier of the terminal device from a first state to a second state, wherein one of the first state and the second state is a dormant state, and the other is an activated state or a deactivated state, wherein the MAC CE is a first MAC CE or a second MAC CE, and wherein each of the first and second MAC CEs is configured to control three state changes among the dormant state, the activated state, and the deactivated state;', 'wherein, when the MAC CE is the first MAC CE,', 'the first MAC CE is used for indicating:
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, and
wherein the first MAC CE is further used for indicating: 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,', '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, and', 'wherein the first MAC CE is further used for indicating: 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,', 'wherein, when the MAC CE is the second MAC CE, the second MAC CE indicates:
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; and', '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; and', '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.', '15. The terminal device according to claim 14, wherein the second MAC CE comprises:
a R domain bit and C domain bits, wherein the R domain bit is a reserved bit, value of which is 0, and wherein each of the C domain bits corresponds to an index of a secondary carrier.', 'a R domain bit and C domain bits, wherein the R domain bit is a reserved bit, value of which is 0, and wherein each of the C domain bits corresponds to an index of a secondary carrier.', '16. A network device, comprising a memory, a processor, an input interface and an output interface, the memory, the processor, the input interface and the output interface are connected through a bus system, the memory is configured to store instructions, and the processor is configured to execute the instructions stored in the memory 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, one of the first state and the second state is dormant state, and the other is activated state or deactivated state, wherein the MAC CE is a first MAC CE or a second MAC CE, and wherein each of the first and second MAC CEs is configured to control three state changes among the dormant state, the activated state, and the deactivated state;
wherein, when the MAC CE is the first MAC CE,
the first MAC CE is used for indicating:
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, and
wherein the first MAC CE is further used for indicating:
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,

wherein, when the MAC CE is the second MAC CE, the second MAC CE indicates:
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; and

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.', '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, one of the first state and the second state is dormant state, and the other is activated state or deactivated state, wherein the MAC CE is a first MAC CE or a second MAC CE, and wherein each of the first and second MAC CEs is configured to control three state changes among the dormant state, the activated state, and the deactivated state;', 'wherein, when the MAC CE is the first MAC CE,', 'the first MAC CE is used for indicating:
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, and
wherein the first MAC CE is further used for indicating:
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,', '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, and', 'wherein the first MAC CE is further used for indicating:', '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,', 'wherein, when the MAC CE is the second MAC CE, the second MAC CE indicates:
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; and', '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; and', '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.']