ronment. Protocol Architecture Figure 11-10 illustrates the protocol stack for the 3G CN. This protocol stack is similar to the one being utilized by GPRS. However, it must be noted that the protocols sitting above RLC and GPRS Tunneling Protocol- User Plane (GTP-U) are for further study by 3GPP. The main difference between the 3G protocol stack and the GPRS stack is the lack of the Subnetwork-Dependent Convergence Protocol (SNDCP), Link Layer Control (LLC), and BSS GPRS Protocol (BSSGP). In addition, Frame Relay has been replaced by the Asynchronous Transfer Mode (ATM) switching technology supporting the ATM Adaptation Layer 5 (AAL5). Also, the Transmission Control Protocol (TCP) will not be used when tunneling data across the Gn interface. Instead, the User Datagram Protocol (UDP) will support all connections. 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. Future Enhancements and Services Future Enhancements and Services Figure 11-10 3G-SGSN 3G-GGSN The 3G protocol stack. GTP-U UDP/IP UMTS and other IMT-2000 3G mobile systems will deliver voice, graphics, video, and other broadband information directly to the user, regardless of location, network, or terminal. These personal communication services will provide terminal and service mobility on fixed and mobile networks, taking advantage of the convergence of existing and future fixed and mobile networks and the potential synergies that can be derived from such con- vergence. The key benefits that UMTS/IMT-2000 promises include improve- ments in quality and security, incorporating broadband and networked multimedia services, flexibility in service creation, and ubiquitous service portability. Networked multimedia can be defined to include services such as Pay-TV Video- and audio-on-demand Interactive entertainment Educational and information services Communication services such as video-tel