Infrastructure equipment, communications devices and methods for compensating for frequency drift of an oscillator of a communications device

An infrastructure equipment forming part of a mobile communications network configured to transmit signals to and receive signals from one or more communications devices, the infrastructure equipment comprising

• a receiver configured to receive signals on the uplink from the one or more communications devices via a wireless access interface of the mobile communications network,
• a transmitter configured to transmit signals on the downlink to the one or more communications devices via the wireless access interface, and
• a controller configured to control the receiver to receive the signals and to control the transmitter to transmit the signals, wherein the controller is configured in combination with the receiver and the transmitter
• to receive uplink signals transmitted from one of the communications devices in a plurality of transmission periods, each of the plurality of transmission periods being separated from a next transmission by a first predetermined period in which the one of the communications devices receives downlink signals from the infrastructure equipment to correct a transmission frequency with respect to a carrier frequency of allocated communications resources, and
• after a last of the transmission periods in which the uplink signals are received from the one of the communications devices, to determine whether the duration of reception of the signals from the one of the communications devices in the last of the transmission periods exceeded the predetermined threshold, and if so to control the transmitter
• to delay transmission of signals to the one of the communications devices for a second predetermined period following the reception of the signals from the one of the communications devices.

An infrastructure equipment forming part of a mobile communications network configured to transmit signals to and receive signals from one or more communications devices, the infrastructure equipment comprising:

• a receiver configured to receive signals on the uplink from the one or more communications devices via a wireless access interface of the mobile communications network,
• a transmitter configured to transmit signals on the downlink to the one or more communications devices via the wireless access interface, and
• a controller configured to control the receiver to receive the signals and to control the transmitter to transmit the signals, wherein the controller is configured in combination with the receiver and the transmitter
• to measure a frequency error of signals received from one of the communications devices, the frequency error being an amount by which a carrier frequency of the received signals differs from a predetermined frequency,
• to transmit, in one or more temporal periods, during which reception of the signals transmitted by and received from the one of the communications devices is paused, a frequency correction signal to the one of the communications devices, the frequency correction signal providing an indication of a correction to compensate for the measured frequency error, and
• to transmit the frequency correction signal on a downlink control channel,
• wherein the frequency correction signal is a plurality of bits indicating a value equal to one of a plurality of predetermined levels of frequency change, the one of the predetermined levels of frequency change being the closest to the measured frequency error.