Component carrier (de)activation in communication systems using carrier aggregation

A communication method comprising:

• reception circuitry of a terminal apparatus receiving a MAC control element including a cluster of bits which indicate an activation/deactivation status of each of at least one secondary component carrier added to a primary component carrier, which is always activated, each of the at least one secondary component carrier corresponding to one bit included in the cluster of bits, and each bit indicating whether a corresponding secondary component carrier should be activated or deactivated, wherein when any one bit among the cluster of bits indicates that its corresponding secondary component carrier should be activated, the cluster of bits further indicate an automatic trigger for sounding reference signal (SRS) transmission;
• processing circuitry of the terminal apparatus activating or deactivating each of the at least one secondary component carrier according to the received MAC control element;
• and
• transmission circuitry of the terminal apparatus starting an SRS transmission on the activated secondary component carrier(s).

A non-transitory computer-readable medium having contents which configure signal processing circuitry to perform a communication method, the communication method comprising:

• receiving a MAC control element including a cluster of bits which indicate an activation/deactivation status of each of at least one secondary component carrier added to a primary component carrier, which is always activated, each of the at least one secondary component carrier corresponding to one bit included in the cluster of bits, and each bit indicating whether a corresponding secondary component carrier should be activated or deactivated, wherein when any one bit among the cluster of bits indicates that its corresponding secondary component carrier should be activated, the cluster of bits further indicate an automatic trigger for sounding reference signal (SRS) transmission;
• activating or deactivating each of the at least one secondary component carrier according to the received MAC control element;
• and
• starting an SRS transmission on the activated secondary component carrier(s).