rections, so forward can use 3x while reverse uses 1x. We believe that it is more likely that cdma2000 service providers will be using multicarrier systems with three 1x carriers forward rather than 3x because the multicarrier option is compatible with cdmaOne. If the market has a leaning toward forward data traffic, then the service provider can al- locate more carriers in that direction. The cdma2000 1x EV-DO standard (1x carrier bandwidth, evolution data only) allows for very high rates at close range in the forward direction. This allows a provider to se- lect a target audience for high-performance data downloads using the fact that the for- ward direction can be time multiplexed (TDMA) as well as code multiplexed (CDMA). This technology will provide excellent support for data services that lean toward the forward direction, such as our Web server example. W-CDMA allows for asymmetry as well. A provider with 15 MHz may decide to use two 5-MHz carriers in the forward direction and only one in reverse. The W-CDMA sys- tem has no requirement for equal numbers of carriers in the two directions. 38.1.2 Shared packet channels Third-generation (3G) CDMA has shared packet channels in addition to dedicated CDMA data service channels. The provider can set aside CDMA capacity for these channels and allow many wireless data terminals to have access to them. The shared channels are high-speed data links, so one terminal can get or send a burst of data at high speed without having to set up a high-speed data channel. The number and ca- pacity of the shared packet channels can be set independently for forward and reverse directions. The shared packet channels set aside capacity for data services so that other subscriber activity does not squeeze them out. Use of the forward shared packet data channel is controlled by the system. The data terminal is told which time intervals on the shared channel contain its data. It is the reverse use of the shared channel that requires coordination through the Medium Ac- Downloaded from D