ists). PBCCH first block (BO) decoding If a PBCCH description is sent on BCCH SI 13, the mobile station listens to the first PBCCH block (B0) on the PDCH carrying PBCCH. The information contained in this first block indicates how many PBCCH blocks are used (and necessarily transmitted on the first blocks of this time slot, according to the multiframe blocks order) through the parameter BS_PBCCH_BLKS. Packet System Information decoding The mobile station then decodes all the PBCCH blocks, carrying the PSI 1, 2, 3bis, 4, 5, and 13. All the necessary information for the mobile station is transmitted on the PSI, and some redundancy occurs with the SI broadcast on BCCH SO that the mobile station only needs to decode PBCCH. The following parameters, among others, are transmitted on the PSI (PBCCH): BS_PCC_CHANS Indicates the number of PDCH carrying PCCCH channels BS PAG_BLKS_RES Indicates the number of blocks on which paging (PPCH) is forbidden on each PDCH carrying PCCCH channels BS_PRACH BLKS (optional) Indicates the number of blocks (UL) reserved for random access (initial resource request on PRACH) 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 Radio and MS-PCUSN Interfaces BS_PCC_CHANS and BS PAG BLKS_RES Useful for the mobile station to determine the paging subgroup it will use when in DRX mode (after expiration of the timer: NON DRX TIMER) Example of PBCCH + PCCCH Configuration The multiplexing of the packet channels on a PDCH is not fixed like in the GSM system. In GPRS, it is managed by some parameters and the follow- ing block order: B0, B6, B3, B9, B1, B7, B4, B10, B2, B8, B5, and B11. Figure 6-10 shows the parameters that manage the multiplexing of the packet channels on the same PDCH: BS_PBCCH_BLKS This indicates the number of PBCCH blocks used to broadcast the PSI. These blocks are always the first bloc