gital 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. Radio and MS-PCUSN Interfaces Radio and MS-PCUSN Interfaces LLC Frames of Variable Length Figure 6-39 LLC Header The RLC/MAC data blocks segment the LLC data. LLC Data LLC Data LLC Data LLC Data LLC Data Level 1: channel coding (FEC) RLC/MAC interleaving burst formatting Header Length Indicator Block Check (1 Byte) Normal Burst Normal Burst Normal Burst Normal Burst Sequence RLC/MAC Frames of Fixed Length RLC/MAC block may carry several LLC frames (not necessarily com- pletely). This is why the RLC header has optional-length indicators in order to delimitate the different LLC frames information. Quality of Service (QoS) A QoS profile is associated with each PDP context and is considered a sin- gle parameter with multiple data transfer attributes. These are defined as Precedence class Delay class Reliability class Peak throughput class Mean throughput class Several possible QoS profiles are defined by these various attributes and as such a PLMN may support a limited number of the profiles. This is implementation-dependent. During the QoS profile negotiation, it is possi- ble for the mobile station to request a value for each of the QoS attributes, including the Home Location Register (HLR) stored subscribed default val- ues. QoS parameters are normally negotiated at subscription or during call setup. The network will negotiate each attribute at a level that is consistent with available GPRS resources. 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. Radio and MS-PCUSN Interfaces Chapter 6 The use of the interface and the group of protocols to handle data trans- fer between the mobile station and the PCUSN are clearly defined in the role of th