In one disclosed embodiment, a mobile unit receives an assigned reverse supplemental channel data rate, for example, as part of a supplemental channel assignment from a base station to the mobile unit in a CDMA spread spectrum communication system. The mobile unit utilizes a profiling table to determine a maximum feasible reverse supplement channel data rate corresponding to a given forward supplemental channel data rate. For example, the profiling table can be constructed by testing the mobile unit to determine what combinations of forward and reverse supplemental channel data rates and operating conditions cause the mobile unit's processor to 'crash'. The mobile unit communicates data over the reverse supplemental channel at a data rate which does not exceed the maximum feasible reverse supplemental channel data rate, for example, by constructing service data units using filler to lower the communication data rate below the maximum feasible reverse supplemental channel data rate.