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. Main GPRS Procedures Main GPRS Procedures Figure 5-8 The network-initiated GPRS detach procedures. GPRS Detach Request Delete PDP Context Request Delete PDP Context Response GPRS Detach Accept Activating a PDP Context for Packet Routing and Transfer Before data can be sent or received, a PDP context (a data address) must be activated (created for the mobile station). The PDP context is used for routing purposes inside the GPRS network. A GPRS subscription con- tains several PDP addresses and an individual PDP context is maintained in the mobile station, SGSN, and GGSN for every PDP address. All PDP contexts for a subscriber are associated with the same MM context for the IMSI of the subscriber. It is possible to inquire and/or set the following parameters: Requested QoS such as the peak bit rate, mean bit rate, delay requirements, service precedence, and reliability level expected Data compression or no data compression such as using V.42 bis data compression on the payload Whether or not to use TCP/IP header compression PDP address and type requested (particularly if an IP or X.25 address are static) 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. Main GPRS Procedures Chapter 5 Each PDP context can be either active or inactive, as seen earlier in Fig- ure 5-3, and three PDP context functions are available-activate, deacti- vate, or modify: The mobile station is responsible for activation and deactivation. GGSN is responsible for activation (for incoming packets) and deactivation. SGSN is responsible for modification. The three functions are only meaningful at the Network Subsystems (NSS) level and do not directly involve the Base Station Subsyst