y from 2G to 3G. There Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. General Cellular Standards Standards for Cellular Systems is a significant difference in migrating from cdmaOne to cdma2000 on a given bandwidth versus migrating from TDMA (GSM or TIA-136) to W-CDMA on a given bandwidth. When migrating from cdmaOne to cdma2000, both the old 2G technology and the new 3G technology are CDMA spread-spectrum technologies that are inherently resis- tant to mutual interference. The 3G carrier can be overlayed on the same frequency and appears as manageable interference to the 2G carrier. The ability of cdmaOne to manage interference from cdma2000 carriers is further enhanced by the use of codes that are orthogonal on both systems. However, when migrating from TDMA to W-CDMA, the 2G TDMA system has no such protection from the interference generated by the W-CDMA carrier. As a result, there are only two ways to deploy W-CDMA. The service provider must either deploy the equipment in a separate frequency or drop TDMA and operate CDMA. Since the providers are already serving 700 million subscribers, dropping TDMA is not a realis- tic option. Instead, W-CDMA must either operate in a previously unused range of spec- trum or slowly edge out TDMA in the existing spectrum. By whatever methods, the cellular providers will continue to upgrade their networks to 3G. This will increase voice capacity and provide high-speed data capacity. At some point, some new use for high-speed data services will the catch corporate and public eyes, and we will see wide use of 3G data technologies. 9.2.3.2 High-speed data. The initiative is succeeding at reaching its goal of sup- porting enhanced data services. Standards for high-speed data have been defined and are being implemented in 2002, only a year or two after they were originally scheduled. The data rates are still 