services to individual subscribers. This is incompatible with carrying voice calls on the same channel because it is not acceptable for a voice call to drop out or experience extremely high interference for a few seconds. As a result, it would be inappropriate for a single subscriber to dominate a carrier supporting voice calls. There are some other issues that will need to be addressed in the design and imple- mentation of 3G standards. With CDMA, high-speed power control is a crucial tool in managing interference, and this power control uses capacity on the carrier. Also, a channel must be maintained at an acceptable error rate rather than be set for the fewest possible errors because having fewer errors requires a higher power level for that one channel, and this produces more interference for other channels on the same CDMA carrier. For cdma2000, support for cmdaOne on the same channel requires backward com- patibility. This limits the flexibility of design because any system must continue to sup- port existing user terminals. As a general rule, the wider the bandwidth a carrier has, the more bits it can carry on each channel. There are two ways of giving an individual subscriber a higher data rate. One approach uses supplemental channels, and the other uses carriers with wider bandwidth. In the first alternative, supplemental channels are provided when they are needed. This is handled differently depending on whether the request is for high-speed data on the reverse channel or on the forward channel. For the reverse direction, the user ter- minal requests additional capacity for a higher data rate, and the base station sets up the supplemental channel. In the forward direction, the base station sets up the sup- plemental channel and informs the user terminal as to what channels to access. As long as the user terminal has only one receiver, the maximum data rate is limited by the maximum capacity of the carrier. The technique of using supplemental channels can only increase the data rate to the maximum data r