Abstract: In a mobile communication system having channels with different bandwidths, a channel bandwidth can be dynamically selected for transmitting data over a connection between a radio access network and a mobile station. According to the invention, a channel bandwidth and also a target for a data error rate for the transmission is selected based on a determined transmission need, i.e. a determined characteristics of the data to be transmitted and on a determined load of a communication resource, e.g. channel power and/or total carrier power used in a cell. By making it possible to dynamically select a data error rate, a connection can, by increasing the data error rate and consequently decreasing the channel power, carry on using a certain channel bandwidth even if at a first instance a load threshold level is achieved for the channel power or the total power used in the cell. Thereby, the capacity of the system can be increased, while at the same time the throughput over the connection is increased.