An apparatus of user equipment, UE, (102, 200) the apparatus comprising: a memory; and processing circuitry in communication with the memory and arranged to: measure a reception, Rx,-transmission, Tx, time difference of a cell specific reference signal from a Primary Cell, PCell, of an evolved NodeB, eNB, the Rx-Tx time difference comprising a time difference between a received timing of a downlink radio frame from the PCell, defined by a first detected path in time, and a transmit timing of an uplink radio frame, the Rx-Tx time difference measured at an antenna connector of the UE (102, 200); send, from the processing circuitry for transmission to the eNB, a report comprising the Rx-Tx time difference value; and after transmission of the report, decode a Timing Advance, TA, Command Media Access Control, MAC, control element from the eNB comprising a TA for a subsequent transmission from the UE (102, 200) to the eNB; wherein the processing circuitry is further arranged to: map the Rx-Tx time difference to a Rx-Tx time difference value based on a first or second table, the first table selected when the UE (102, 200) is a Time Division Duplexing, TDD, UE and the second table selected when the UE (102, 200) is a Frequency Division Duplexing, FDD, UE, the first and second tables comprising different mappings between a measured Rx-Tx time difference and a Rx-Tx time difference value; characterised in that the first table comprises a 2T s resolution for a Rx-Tx time difference of less than 4720T s and an 8T s resolution for a Rx-Tx time difference of at least 4720T s; and wherein, when the first table is selected, a Rx-Tx time difference value of 0 for a Rx-Tx time difference of less than 626T s is selected. a memory; and processing circuitry in communication with the memory and arranged to: measure a reception, Rx,-transmission, Tx, time difference of a cell specific reference signal from a Primary Cell, PCell, of an evolved NodeB, eNB, the Rx-Tx time difference comprising a time difference between a received timing of a downlink radio frame from the PCell, defined by a first detected path in time, and a transmit timing of an uplink radio frame, the Rx-Tx time difference measured at an antenna connector of the UE (102, 200); send, from the processing circuitry for transmission to the eNB, a report comprising the Rx-Tx time difference value; and after transmission of the report, decode a Timing Advance, TA, Command Media Access Control, MAC, control element from the eNB comprising a TA for a subsequent transmission from the UE (102, 200) to the eNB; measure a reception, Rx,-transmission, Tx, time difference of a cell specific reference signal from a Primary Cell, PCell, of an evolved NodeB, eNB, the Rx-Tx time difference comprising a time difference between a received timing of a downlink radio frame from the PCell, defined by a first detected path in time, and a transmit timing of an uplink radio frame, the Rx-Tx time difference measured at an antenna connector of the UE (102, 200); send, from the processing circuitry for transmission to the eNB, a report comprising the Rx-Tx time difference value; and send, from the processing circuitry for transmission to the eNB, a report comprising the Rx-Tx time difference value; and after transmission of the report, decode a Timing Advance, TA, Command Media Access Control, MAC, control element from the eNB comprising a TA for a subsequent transmission from the UE (102, 200) to the eNB; wherein the processing circuitry is further arranged to: map the Rx-Tx time difference to a Rx-Tx time difference value based on a first or second table, the first table selected when the UE (102, 200) is a Time Division Duplexing, TDD, UE and the second table selected when the UE (102, 200) is a Frequency Division Duplexing, FDD, UE, the first and second tables comprising different mappings between a measured Rx-Tx time difference and a Rx-Tx time difference value; characterised in that the first table comprises a 2T s resolution for a Rx-Tx time difference of less than 4720T s and an 8T s resolution for a Rx-Tx time difference of at least 4720T s; and wherein, when the first table is selected, a Rx-Tx time difference value of 0 for a Rx-Tx time difference of less than 626T s is selected. map the Rx-Tx time difference to a Rx-Tx time difference value based on a first or second table, the first table selected when the UE (102, 200) is a Time Division Duplexing, TDD, UE and the second table selected when the UE (102, 200) is a Frequency Division Duplexing, FDD, UE, the first and second tables comprising different mappings between a measured Rx-Tx time difference and a Rx-Tx time difference value; characterised in that the first table comprises a 2T s resolution for a Rx-Tx time difference of less than 4720T s and an 8T s resolution for a Rx-Tx time difference of at least 4720T s; and wherein, when the first table is selected, a Rx-Tx time difference value of 0 for a Rx-Tx time difference of less than 626T s is selected.