A method performed by a serving cell (512, 600), comprising: transmitting/receiving signals to/from a plurality of user equipments, UEs, (102, 200); and transmitting at least one subframe for a physical downlink control channel, PDCCH, formed in accordance with a first Downlink Control Information, DCI, format, the first DCI format indicating a transmission state of the serving cell (512, 600), wherein the plurality of UEs (102, 200) monitor the PDCCH of the serving cell when the serving cell is in a first transmission state, and wherein the plurality of UEs (102, 200) refrain from monitoring the PDCCH of the serving cell (512, 600) when the serving cell is in a second transmission state; providing, while in the first transmission state, a scheduling assignment for at least one UE (102, 200) of the plurality of UEs (102, 200), wherein the first DCI format is transmitted in at least one subframe of a respective modification period of a plurality of modification periods, and wherein the transmission state of the serving cell (512, 600) indicated by the first DCI format transmitted in the at least one subframe of the respective modification period of the plurality of modification periods is independent of that of a transmission state of other serving cells (512, 600) indicated by the first DCI format; and transmitting higher layer signaling specifying the at least one subframe in which the UE (102, 200) monitors the first DCI format. transmitting/receiving signals to/from a plurality of user equipments, UEs, (102, 200); and transmitting at least one subframe for a physical downlink control channel, PDCCH, formed in accordance with a first Downlink Control Information, DCI, format, the first DCI format indicating a transmission state of the serving cell (512, 600), wherein the plurality of UEs (102, 200) monitor the PDCCH of the serving cell when the serving cell is in a first transmission state, and wherein the plurality of UEs (102, 200) refrain from monitoring the PDCCH of the serving cell (512, 600) when the serving cell is in a second transmission state; providing, while in the first transmission state, a scheduling assignment for at least one UE (102, 200) of the plurality of UEs (102, 200), wherein the first DCI format is transmitted in at least one subframe of a respective modification period of a plurality of modification periods, and wherein the transmission state of the serving cell (512, 600) indicated by the first DCI format transmitted in the at least one subframe of the respective modification period of the plurality of modification periods is independent of that of a transmission state of other serving cells (512, 600) indicated by the first DCI format; and wherein the first DCI format is transmitted in at least one subframe of a respective modification period of a plurality of modification periods, and wherein the transmission state of the serving cell (512, 600) indicated by the first DCI format transmitted in the at least one subframe of the respective modification period of the plurality of modification periods is independent of that of a transmission state of other serving cells (512, 600) indicated by the first DCI format; and transmitting higher layer signaling specifying the at least one subframe in which the UE (102, 200) monitors the first DCI format.