 from the mobile to fixed nodes use normal routing. GPRS, by contrast, uses tunneling in both directions. 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. GPRS Introduction GPRS Introduction GSM and NA-TDMA Evolution Both GSM and NA-TDMA are evolving from 2G to 3G and GPRS plays an important role in this evolution. Some of the key points to note are as follows: As evident, attempts are made to seek synergy between the two TDMA base systems now (as opposed to what happened 10 years ago). GSM-GPRS standards and concepts are being adopted in North American TDMA as GPRS-136. The radio interface is being adapted to 30-kHz channels and an IS-136 DCCH channel structure. In fact, many of the North American carriers (AT&T Wireless and Voice Stream, among others) are planning to offer GPRS on GSM as an evolution from the NA-TDMA architecture). EDGE has adopted the eight-PSK-modulation scheme that is used for 136+. 136HS and EDGE are being developed with synergy in mind. UWC-136 has embraced the GPRS/EDGE architecture for 200- kHz-wide 136HS Outdoors. The North American and European proposals differ for the 2.0-Mbps systems. UWC-136 continues to use a purely TDMA scheme, whereas CDMA-based UTRA is the Radio Transmission Technology (RTT) of choice for ETSI. GPRS Terminals GPRS terminals can be grouped in three GPRS mobile station classes, each having different capabilities to fulfill market needs: Class A A mobile station that can make/receive calls on both GSM and GPRS simultaneously. Class B The mobile station can make and/or receive calls on either GSM or GPRS but not simultaneously. Class C The mobile station can be either in GPRS or in GSM mode (manually selected). GPRS will drive the convergence of mobile computing and wireless. In addition, it is expected that apart from the traditional wireless terminal Downloaded from Digital Engineering Library