ate of the carrier. To achieve higher data rates, carriers with greater capacity are needed. This problem is resolved in 3G CDMA implementations by offering carriers with wider bandwidth. 3 These carriers have higher chip rates and bit rates than the nar- rower 1.25-MHz cdmaOne carriers. This increases the maximum data rate that can be offered on a single carrier. It is important to note that while the maximum data rate does increase, spectral efficiency does not. Using 1 percent of a 3x carrier is no more ef- ficient than using 3 percent of a 1x carrier. 3This is the W in W-CDMA. 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. Quality of Service (QoS) Quality of Service (QoS) The carrier bandwidth for 3G systems will migrate from the second-generation (2G) standard of 1.25 MHz up to 5 MHz in the near future. cdma2000 has two ways of of- fering 5-MHz service, 3x is a single 3.75-MHz carrier (5 MHz with guard bands), and multicarrier is three 1x carriers coordinated to offer data rates similar to 3x. The 3G standards for cdma2000 allow the possibility of even wider carriers, each a multiple of a 3x carrier, 6x with 7.5 MHz of bandwidth, 9x with 11.25 MHz, and 12x with 15 MHz plus whatever guard bands are required. 17.2.5 Allocating voice and data carriers So far we have been focusing our discussion on the data capacity of individual channels and the methods for increasing that capacity. There is a separate capacity challenge for high-speed data services looming in the near future. How will the system perform when many subscribers all want high-speed data services on the same cell sector? All the ad- vanced planning and careful design of standards and specifications done thus far will not answer this question. The proof is in the pudding, and sometime in the next few years, as subscribers use more and more wireless data service, the pudding wi