A method comprising: receiving, at user equipment, UE, a downlink radio resource control, RRC, message including a PhysicalCellGroupConfig information element, wherein: the downlink RRC message is used to configure RRC for the UE; and the PhysicalCellGroupConfig IE is used to configure a cell group and a radio network temporary identifier, RNTI, wherein configuration parameters for the cell group are provided in the PhysicalCellGroupConfig IE; determining the RNTI associated with the UE based on the PhysicalCellGroupConfig IE of in the downlink RRC message; using the PhysicalCellGroupConfig IE to configure the cell group, wherein the RNTI is configured for cells within the cell group; receiving an uplink grant for the cells within the cell group; and applying an RNTI-based modulation coding scheme, MCS, determination rule to the uplink grant in response to the RNTI being configured via the PhysicalCellGroupConfig IE, wherein applying the RNTI-based MCS determination rule includes: obtaining information from a physical downlink control channel, PDCCH, wherein the information includes downlink control information, DCI, and wherein the DCI includes a set of cyclic redundancy check, CRC, bits; applying a first MCS table as a result of determining one or more CRC bits of the set of CRC bits if the information are scrambled with the RNTI; and applying a second MCS table as a result of determining one or more CRC bits of the set of CRC bits if the information are not scrambled with the RNTI, wherein the first MCS table is associated with a higher channel code rate than the second MCS table. receiving, at user equipment, UE, a downlink radio resource control, RRC, message including a PhysicalCellGroupConfig information element, wherein: the downlink RRC message is used to configure RRC for the UE; and the PhysicalCellGroupConfig IE is used to configure a cell group and a radio network temporary identifier, RNTI, wherein configuration parameters for the cell group are provided in the PhysicalCellGroupConfig IE; the downlink RRC message is used to configure RRC for the UE; and the PhysicalCellGroupConfig IE is used to configure a cell group and a radio network temporary identifier, RNTI, wherein configuration parameters for the cell group are provided in the PhysicalCellGroupConfig IE; determining the RNTI associated with the UE based on the PhysicalCellGroupConfig IE of in the downlink RRC message; using the PhysicalCellGroupConfig IE to configure the cell group, wherein the RNTI is configured for cells within the cell group; receiving an uplink grant for the cells within the cell group; and applying an RNTI-based modulation coding scheme, MCS, determination rule to the uplink grant in response to the RNTI being configured via the PhysicalCellGroupConfig IE, wherein applying the RNTI-based MCS determination rule includes: obtaining information from a physical downlink control channel, PDCCH, wherein the information includes downlink control information, DCI, and wherein the DCI includes a set of cyclic redundancy check, CRC, bits; applying a first MCS table as a result of determining one or more CRC bits of the set of CRC bits if the information are scrambled with the RNTI; and applying a second MCS table as a result of determining one or more CRC bits of the set of CRC bits if the information are not scrambled with the RNTI, wherein the first MCS table is associated with a higher channel code rate than the second MCS table. obtaining information from a physical downlink control channel, PDCCH, wherein the information includes downlink control information, DCI, and wherein the DCI includes a set of cyclic redundancy check, CRC, bits; applying a first MCS table as a result of determining one or more CRC bits of the set of CRC bits if the information are scrambled with the RNTI; and applying a second MCS table as a result of determining one or more CRC bits of the set of CRC bits if the information are not scrambled with the RNTI, wherein the first MCS table is associated with a higher channel code rate than the second MCS table.