- munities of interest. The trend is moving away from storing information locally in specific software packages on PCs to remotely on the Internet. When you want to check your schedule or contacts, instead of using a dedi- cated contact manager on the PC, you go onto the Internet site such as a portal. Hence, Web browsing is a very important application for GPRS. Because it uses the same protocols, the GPRS network can be viewed as a subnetwork of the Internet with GPRS-capable mobile phones being viewed as mobile hosts. This means that each GPRS terminal can potentially have its own Internet Protocol (IP) address and will be addressable as such. This really depends on the implementation by the operator. The impact to the overall Global Systems for Mobile (GSM) operation will dictate what and how much influence the operator applies to the GPRS network initially. 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. Function of GPRS Elements Function of GPRS Elements Impact on the Base Station Subsystem (BSS) No major changes occur inside the Base Station Subsystem (BSS). How- ever, two functions must be inserted inside the BSS for the GPRS func- tionality to work. These are listed in the following section and shown in Figure 4-1: Channel Codec Unit (CCU) Deals mainly with the new coding schemes (as well as any compression coding techniques) Packet Control Unit (PCU) Responsible for providing the interface with the GPRS network (Frame Relay) and managing time slot allocation The CCU is located in the Base Transceiver System (BTS) without any hardware impact. The PCU can be located at the Network Service Subsys- tem (NSS) side or at the Base Station Controller (BSC) side, depending on the network engineering rules or any cost constraints (such as long- distance Pulse Coded Modulation [PCM] interfaces). However, it is a part of the BSS. The European 