LTE system information is one of the key aspects of the air
interface. It consists of the Master Information Block (MIB) and a number of System
Information Blocks (SIBs). The MIB is broadcast on the Physical Broadcast Channel
(PBCH), while SIBs are sent on the Physical Downlink Shared Channel (PDSCH) through
Radio Resource Control (RRC) messages. SIB1 is carried by "SystemInformationBlockType
1" message. SIB2 and other SIBs are carried by "SystemInformation (SI)" message.
An SI message can contain one or several SIBs.
The MIB is the first thing a
UE looks for after it achieves downlink synchronization. The MIB carries the
most essential information that is needed for the UE to acquire other
information from the cell. It includes:
SIB1 is carried in a SystemInformationBlockType1
message. It includes information related to UE cell access and defines the schedules
of other SIBs, such as:
SIB2 contains radio resource
configuration information common for all UEs, including:
SIB3 contains information
common for intra-frequency, inter-frequency, and/or inter-RAT cell reselection.
This information does not necessarily apply to all scenarios; please refer to 3GPP
TS 36.304 for the details. The basic parameters include:
SIB4 contains the intra-frequency
neighboring cell information for Intra-LTE intra-frequency cell reselection,
such as neighbor cell list, black cell list, and Physical Cell Identities (PCIs)
for Closed Subscriber Group (CSG). CSG
can be used to support Home eNBs.
SIB5 contains the neighbor
cell related information for Intra-LTE inter-frequency cell-reselection, such
as neighbor cell list, carrier frequency, cell reselection priority, threshold
used by the UE when reselecting a higher/lower priority frequency than the
current serving frequency, etc.
(Note that 3GPP states that LTE neighbor cell
search is feasible without providing an explicit neighbor list. Since the UE can
do blind detection of neighbor cells in LTE, the broadcast of LTE neighbor
cells is optional.)
well written article and very informative. Found a complete list of functionalities of SIB 2