Determining a power relationship linking the transmit powers of user data and associated control data

In a communication system where user data and associated control data are transmitted from one entity to another, a power relationship linking the transmit powers of the user data and associated control data is determined at least partly dependent on a received quality of the associated control data. For example, if the bit error rate (BER) of the received control data is found to be below a desired threshold, an increase in the control transmit power is required and a new power relationship (e.g. a different offset or ratio) is determined which enables the required increase in the control transmit power whilst maintaining the data transmit power at a level set by an outer power control loop. Conventionally, a set relationship is established between the data and control transmit powers and the transmit power of the data channel is optimised using inner and outer loop power control. However, in such systems the control power is not optimised as it merely follows the data power according to the set relationship. Implementation of the described method results in the ability to maintain the transmit power of the user data, (e.g. on a Dedicated Physical Data Channel (DPDCH) in UMTS), at an optimum power level set by a power control process, whilst ensuring that associated control data, (e.g. on a Dedicated Physical Control Channel (DPCH)), is also transmitted at an optimum power level. The invention ensures reception of the user data and control data with an acceptable error rate causing minimum interference to other users. New quality targets may also be generated for the power loop control processes.