can be overlaid and combined. 8 There is a multicarrier mode for cdma2000 3x that not only sends its data on three carriers at 1.2288 Mchips per second but also coordinates its Walsh codes to be orthogonal the cdmaOne channels in use. 10.2.4 cdma2000 forward channel coding The forward modulation scheme in cdma2000 has separate in-phase and quadrature bit streams as opposed to cdmaOne, where they are combined in the final stage of pro- cessing gain. This gives cdma2000 an automatic factor of 2 in bit rate capacity at the expense of a factor of 2 in processing gain. cdma2000 supports two kinds of traffic channels, fundamental and supplemental. The fundamental channel is used for voice calls and for low-bit-rate signaling during a data call, the same 9600-bit-per-second RS1 and 14.4-kbps RS2 as cdmaOne. Supplemental channels can be dedicated to a single user terminal or shared by mul- tiple packet mode users. Every user of a supplemental channel must have an active fundamental channel that may do nothing more than power control and low-bit-rate signaling at one-eighth rate and one-eighth power. Forward supplemental channels are controlled by the wireless service provider, SO subscribers can share fixed supplemen- tal channels in packet mode or can have their own supplemental channels, one or more Even if there were no specific provision for carrier coordination, the direct-sequence spread- spectrum (DSSS) principle makes the carrier resistant to narrowband jamming, even if the nar- rowband jamming is from another DSSS carrier. 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. Worldwide CDMA Standards Worldwide CDMA Standards on the same forward link. In the forward direction, the base station does the packet scheduling and tells the user terminals which time slots are assigned to them. To support the wide range of channel data rates, the Walsh co