System Information 19 – SIB19 For 5g Satellite NTN

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Introduction 

In 5G NR, System Information Block #19 (SIB19) carries information for UE to access Non Terrestrial Network- NTN or 5G Satellite Network.

SIB19 was introduced by 3GPP in Release 17 providing NTN-specific parameters for serving cell and/or neighbor cells. It contains satellite assistance information, for example, Ephemeris data, common timing advance parameters, koffset, validity duration for UL synchronization epoch time, cell reference location, cell stop time.

SIB19 For 5g Satellite NTN

SIB 19 Transmission Details

  • Signaling radio bearer: Not Applicable
  • RLC-SAP: TM
  • Logical channels: BCCH
  • Transport Channel: DL-SCH
  • Physical Channel: PDSCH
  • Scrambling RNTI :  SI-RNTI
  • Direction: gNB to UE

SIB 19 Information Elements

The description of SIB19 Information Element as defined in 3GPP Specification 38.331 is shown in the figure below

SIB 19 Information Elements

  • ntn-Config: Provides parameters needed for the UE to access NR via NTN access such as Ephemeris data, common TA parameters, k_offset, validity duration for UL sync information and epoch.
  • t-Service: Indicates the time information on when a cell provided via NTN quasi-Earth fixed system is going to stop serving the area it is currently covering. The field indicates a time in multiples of 10 ms after 00:00:00 on Gregorian calendar date 1 January, 1900 (midnight between Sunday, December 31, 1899 and Monday, January 1, 1900). The exact stop time is between the time indicated by the value of this field minus 1 and the time indicated by the value of this field
  • referenceLocation: Reference location of the serving cell provided via NTN quasi-Earth fixed system and is used in location-based measurement initiation in RRC_IDLE and RRC_INACTIVE, as defined in TS 38.304
  • distanceThresh: Distance from the serving cell reference location and is used in location-based measurement initiation in RRC_IDLE and RRC_INACTIVE, as defined in TS 38.304 [20]. Each step represents 50m.

Why SIB 19 Required?

  • Cell Re-selection: SIB 19 in NTN gives UE vital information about nearby cells or satellite gateways. Similar to its function in terrestrial networks, this data helps UEs decide which satellite or gateway to connect to.
  • Selecting a Satellite or Gateway: SIB 19 assists UEs in selecting the best satellite or gateway in NTN, where they may have several options depending on factors like signal strength, quality, and other network-related data.
  • Seamless Handovers: SIB 19 helps ensure smooth handovers for mobile users in NTN by giving information about nearby cells or gateways and their suitability for handover. This is especially helpful for users moving across different satellite beams or gateways.
  • Resource Allocation: Information about the distribution and administration of resources within the NTN may also be found in SIB 19. UEs can improve their connectivity and grasp the resources that are available with the aid of this data.
  • Network Efficiency: SIB 19 enhances the overall performance and efficiency of the NTN by giving UEs precise and current information about the state of the network, including the satellites and gateways that are available.

SIB 19 Sample Log

A Sample Log is shown in following figure showing the detailed information.

SIB 19 Sample Log

5G System Information Summary 

A Summary of All System Information Blocks for 5G NR

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