LTE System Information: Part 2

Expert Opinion

Expert Opinion
Short LTE articles and opinions by our team of Subject Matter Experts (SMEs)

LTE System Information: Part 2

  • Comments 1

In E-UTRAN, SIBs 6, 7, 8 carry information for IRAT cell reselection to UTRAN, GERAN, and CDMA2000 systems respectively. SIB 1 and SIB 3 also carry IRAT related information.

7.       SIB6 contains information for IRAT cell reselection to UTRAN, such as:

  • Carrier frequency List: a list of neighboring UTRAN carrier frequencies
  • Cell reselection priority: the absolute priority
  • Q_RxLevMin: the minimum required Rx level
  • ThreshX-high/ThreshX-low: threshold used by the UE when reselecting a higher/lower priority frequency than the current serving frequency
  • T-ReselectionURTA: cell reselection timer value for UTRAN
  • Speed dependent reselection parameters

In UTRAN, the IRAT related information is broadcasted in SIBs 6, 18, 19, as well as SIBs 3 and 4. SIB 19 is new to 3GPP Release 8.

8.       SIB7 contains information for IRAT cell reselection to GERAN, such as:

  • Carrier Frequency Info List: a list of neighboring GERAN carrier frequencies
  • Cell reselection priority: the absolute priority
  • Q_RxLevMin: the minimum required Rx level
  • ThreshX-high/ThreshX-low: threshold used by the UE when reselecting a higher/lower priority frequency than the current serving frequency
  • T-ReselectionGERA: cell reselection timer value for GERAN
  • Speed dependent reselection parameter

In GSM/GERAN, system information from second quarter is modified in 3GPP Release 8 to include LTE-related cell-reselection parameters.

9.       SIB8 contains information for IRAT cell reselection to eHRPD (evolved High Rate Packet Data, which is the 1xEV-DO Rev.A with the support of connectivity to Evolved Packet Core of LTE), such as:

  • Information for searching eHRPD: carrier frequencies, system time info for PN synchronization, and the search window size
  • Pre-registration info for eHRPD (optional): required or not. The pre-registration procedure intends to minimize the service interruption time and accelerate the handover by allowing the UE to pre-register with the CDMA 2000 eHRPD system when the UE is still connected with the E-UTRAN. When the UE is connected to eHRPD, it may also pre-register with E-UTRAN. The pre-registration may happen well ahead of the actual handover. The registration Zone ID is also given (eHRPD or 1xEV-DO Sessions belong to an RNC and hence apply to certain zones).
  • Cell reselection thresholds and parameters: ThreshX-high, ThreshX-low, T-reselectionCDMA2000, Speed dependent reselection parameter. The E-UTRAN can prioritize the selection of the technology by the UE by setting the cell reselection parameters properly.
  • Neighbor cell list for monitoring potential eHRPD target cells.

10.   SIB9 contains a Home eNB name. The home eNB is the femto-cell in the context of LTE, a small base station used in residential area or by small businesses. 

11.   SIB10 is for an ETWS (Earthquake and Tsunami Warning System) primary notification. ETWS is a public warning system. The paging procedure is used to inform the ETWS capable UEs in RRC idle and RRC connected modes to listen to SIB10 and SIB11.

12.   SIB11 is for an ETWS secondary notification.