 enhance data capabilities in existing cdmaOne networks or in standalone data networks. With existing CDMA networks, a number of channels are changed from voice to data. Using a combination of TDM and CDMA, IS-95 HDR shares each channel among several users, but on an as-needed basis rather than as fixed time slots, as in TDMA. CDMA2000 promises a 2.4Mbps peak data rate in a standard 1.25MHz CDMA voice channel. The IS-95 HDR data rate varies, depending on the distance between the mobile phone and the base station. Some 94% of current 3G deployments use CDMA2000, but this represents only a fraction of all operators. As more GSM operators convert to 3G W-CDMA tech- nology and implement HSDPA, HSDPA could dwarf CDMA2000. Multicarrier Base Transceiver Station 1X/IS-95 Mobile Switching 1X/IS-95 RF Carrier Center Base Station 1xEV-DO Controller Packet Data Internet RF Carrier 1xEV-DO Serving Node Integrated 1x and 1xEV-DO Figure 14.8 A CDMA2000 network Chapter 14 Wireless WANs At the beginning of 2006, there were more than 300 million subscribers to CDMA networks, with an average growth rate of around 5 million subscribers per month, and CDMA2000 had surpassed 225 million subscribers as of March 2006 (see the CDMA Development Group Web site, at www.cdg.org). CDMA2000 represents an entire family of technologies, including the following: CDMA2000 1X RTT (Radio Transmission Technology)-This technology can double the voice capacity of cdmaOne networks, delivering peak rate packet data speeds of 153Kbps downstream (Release 0) and 307Kbps down- stream (Release 1) in mobile environments, using a single 1.25MHz carrier, in new or existing spectrum. Enabled services include entertainment (e.g., playing a videogame with a friend), e-mail and picture transfer (e.g., using a camera phone to send a photo postcard), and location/traffic/GPS service (e.g., navigating through rush hour or finding the nearest grocery store). CDMA2000 1xEV-DO (Enhanced Version-Data Only)-This 3G technol- ogy uses a separate 1.25MHz carrier for data, prov