s and short movies, there are two techniques that reduce QoS requirements below what broadcast television requires while still being acceptable to customers. One is to provide images at lower resolution, which are either shown on a smaller screen, appear more grainy, or both. The other is to use video streaming, which uses buffering and allows the start of play of the video image prior to completion of file download. Streaming also can be used for compact disk-quality music transmission. For our pur- poses, this brief introduction to the role of video in convergence suffices. In cellular 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. Hybrid Voice-Data Networks Key Data Concepts networks, video is not yet an important issue. Until the high-capacity standards of full 3G implementation prove their cost-effectiveness, video transmission over the cellular network is not a significant part of our capacity planning. When these services become available, data rates will be close to what is found in landline digital subscriber line (DSL), and it is likely that technologies such as video streaming, which are acceptable in that environment, will be acceptable for cellular subscribers as well. With our background in data systems and convergence complete, we now turn to the transmission of data over cellular networks. There are two sets of standards that sup- port user data on cellular networks: the short message service (SMS) and its descen- dants, which carry limited data over the signal channel without establishing a call, and the data-carrier services of 2.5G and 3G networks. We will look at each of these in turn. 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. Source: CDMA CAP