In a method of adjusting a modulation and coding scheme (MCS) level for a transmission on a communication channel between a base station and a mobile terminal, at the base station: a target value for an error metric is defined; the error metric is measured; an MCS offset based on a degree of deviation of the measurement of the error metric from the target value is determined; an indication of a channel quality measurement for the communication channel is received from the mobile terminal; a pre-adjusted MCS level corresponding to the indication of the channel quality measurement is determined using a fixed mapping between a set of channel quality levels and a corresponding set of MCS levels; an adjusted MCS level is determined by adding the MCS offset to the pre-adjusted MCS level; and the adjusted MCS level is assigned to the transmission.