ke 16,384 bytes, so a 100-byte file wastes 16,284 bytes, the rest of the disk cluster. 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. CDMA Data Capacity Principles Capacity and Quality Principles 29.3 cdmaOne Data Capacity (2G) While cdmaOne is almost entirely a voice call system, it supports several distinct data modes, including short message service (SMS), asynchronous data (modems), facsimile (fax), and packet data. These are handled by the same CDMA channels as voice traffic with different handling at the user terminal and system ends. This makes sense for the services and data rates of second-generation (2G) systems. SMS is handled by the paging channel, so user terminals can handle short messages even while engaged in a voice call. Since cdmaOne short messages are limited to 160 bytes and each character is a press of a button, we doubt that SMS will be a cdmaOne capacity issue as far as the air interface is concerned. 29.3.1 Data over voice-coded links Asynchronous data and fax services are sent over cdmaOne channels set up as circuit- switched service with a dedicated path using the Radio Link Protocol (RLP) described in Sec. 10.1.1. The RLP manages the data communication with automatic repeat request (ARQ), (FEC), and flow control, so the user mobile data terminal and the equipment at the other end of the call see a normal asynchronous data link or fax signal. While the data or fax service uses a normal 19.2-kilobit data stream, the cdmaOne system uses its own service option 4 for asynchronous data service and service option 5 for group 3 fax. Since there is no speech, there are no voice pauses, so the partial rates may not be used. Fax service is a continuous stream of bits, so it runs at full rate for the entire call in the direction the fax is being sent. Using the IS-95B protocols, as many as eight voice channels can be bundled