s used on the PDTCH, PACCH, PTCCH, PAGCH, PPCH, PBCCH, and PNCH. The information relative to these packet channels is transmitted onto radio blocks mapped onto four consecutive normal bursts. A normal burst contains 26 bits for the training sequence, 2 blocks of 58 bits for information. More precisely, it contains 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 Normal Burst: used for PDTCH, PACCH, PTCCH, PAGCH, PPCH and PBCCH Figure 6-38 Normal burst format. Training Guard Sequence Period 57 encrypted bits 26 bits 57 encrypted bits Normal Normal Normal Normal Burst Burst Burst Burst 8 bits for CSI 2 blocks of 57 information bits and two stealing flags, which are used in GPRS to indicate the coding scheme used (CS-1 to CS-4). It also contains two sets of three tail bits, and 8.25 bits for the guard period. The training sequence depends on the BCC (BSIC) of the cell, SO eight training sequences are possible, showing a very low correlation between each other in order to correctly differentiate the information destined to one mobile station from the information broadcast in neighboring cells. Access Burst The access burst format is used for network access and TA update (UL) only, using the PRACH (or RACH) channel. An access burst contains 41 bits for the training sequence, 36 bits for the information, and 8 and 3 tail bits at the beginning and the end of the burst, respectively. The guard period has 68.25 bits. RLC Layer Segmentation LLC frames are variable length, whereas RLC/MAC blocks are fixed length (depending though on the coding scheme used; the coding scheme is directly linked to the protection added to the rough information before transmission on the radio interface). Therefore, one LLC frame may be spread onto several RLC/MAC blocks, as shown in Figure 6-39, and conversely, one Downloaded from Di