1.5 System Information
System information is sent to MS from network in broadcast form. It informs all the MSs within the coverage area of location area, cell selection and re-selection, neighbor cell information, channel allocation and random access control. By receiving system information, MS can quickly and accurately locate network resources and make full use of all kinds of services that network provides. There are 16 types of system information: type1, 2, 2bis, 2ter, 3, 4, 5, 5bis, 5ter, 6, 7, 8, and 13.
System information is transmitted on BCCH or SACCH. MS receives system information in different mode from different logic channel.
In idle mode, system information 1– 4, 7, and 8 are transmitted on BCCH ;
In communication mode, system information 5 and 6 are transmitted on SACCH;
The content of system information is as follows:
System information 1：cell channel description + RACH control parameter, transmitted on BCCH
System information 2： frequency description of neighbor cell + RACH control information + network color code (NCC) permitted, transmitted on BCCH, used for cell re-selection
System information 2bis： Extended neighbor cell BCCH frequency description + RACH control information, transmitted on BCCH, used for cell re-selection.
System information 2ter： Extended neighbor cell BCCH frequency description, transmitted on BCCH, used for cell re-selection.
System information 3： Cell identity + location area identity (LAI) + control channel description + cell selection + cell selection parameter + RACH control parameter, transmitted on BCCH.
System information 4： LAI + cell selection parameter + RACH control parameter + CBCH channel description + CBCH mobile configuration, transmitted on BCCH.
System information 5： Neighbor cell BCCH frequency description, transmitted on SACCH channel, used for cell handover.
System information 5bis： Extended neighbor cell BCCH frequency description, transmitted on SACCH channel, used for cell handover.
System information 5ter： Extended neighbor cell BCCH frequency description, transmitted on SACCH channel, used for cell handover.
System information 6： Cell Global Identification (CGI) + cell option＋NCC Permitted, transmitted on SACCH.
System information 7： cell re-selection parameter
System information 8： cell re-selection parameter
BCCH is a low-capacity channel, every 51 multiframes ((235 ms) have only four frames (one information block) to transmit a 23 byte LAPDm message.
Each information unit contains:
Cell channel description contains all the frequencies used in this cell.
RACH control information contains parameters such as Max Retrans, TX_integer, CBA, RE, EC, and AC CN.
Neighbor cell BCCH frequency description contains the BCCH frequency that the neighbor cell uses.
Allowed PLMN is used to provide NCC Permitted that MS monitors on BCCH TRX.
Control channel description contains parameters such as MS ATTACH/DEATTACH allowed Indicator ATT, BS-AG-BLKS-RES, CCCH-CONF, BA-PA-MFRMS, and T3212.
Cell selection contains parameters such as power control (PWRC) indication, discontinuous Transmission (DTX) indication, and RADIO-LINK-TIMEOUT.
Cell selection parameter contains parameters such as cell re-selection hysteresis, MS-TXPWR-MAX-CCH, and RXLEV-ACCESS-MIN.
CBCH channel description contains channel type and TDMA deviation (the combination mode of dedicated channel), timeslot number (TN), training sequence code (TSC), hopping frequency channel indication H, mobile allocation index offset (MAIO), hopping frequency sequence number (HSN) and absolute radio frequency channel number ( ARFCN).
CBCH mobile configuration contains the relationship between hopping channel sequence and cell channel description.
Cell re-selection parameter contains CELLRESELIND, cell bar qualify (CBQ), cell reselection offset (CRO), temporary offset (TO), and penalty time (PT).
1.5 System Information