The number of measurements being performed in a telecommunications system can be reduced by performing a predetermined measurement in Cell A and in co-located Cell B, step 1, for example a received signal code power (RSCP) measurement. The difference between the two signals is determined, and stored for future reference, step 3. Once the difference value has been established, the mobile station no longer needs to perform measurements on both Cell A and Cell B. Instead, if a subsequent measurement is made on Cell A, step 5, the network can estimate the measurement for Cell B based on the difference signal previously determined, step 7.