deactivating manner of the uplink r 1 identifying whether the command is valid for uplink or downlink the value 1 indicates that it is valid for downlink and 0 indicates that it is valid for uplink this bit is only valid under the explicit activating deactivating manner of the uplink r 2 identifying whether the command is the explicit or implicit activating deactivating command the value 1 indicates the implicit command and 0 indicates the explicit command in the mac layer activating deactivating control signaling 1 bit is defined to identify whether the command is the explicit or implicit activating deactivating command in the mac layer activating deactivating control signaling 1 bit is defined to identify whether the command is valid for uplink or downlink the bit is only valid under the explicit activating deactivating manner of the uplink in the mac layer activating deactivating control signaling 1 bit is defined to identify whether the current byte is followed by another byte the bit is only valid under the explicit activating deactivating manner of the uplink the above the mac layer activating deactivating control signaling is merely an example rather than a limiting to the signaling in practice it may be modified as required for example 1 or 0 may has other meanings and the number of cells that can be aggregated by the ue is not limited to 5 but can be any other value referring to fig9 an apparatus 900 of activating an uplink of a secondary cell of a ue according to an embodiment of the invention is described below as shown in.