Feature #1630

Implement SI2quater generation in OpenBSC / OsmoBTS

Added by laforge almost 5 years ago. Updated over 4 years ago.

Target version:
Start date:
Due date:
% Done:


Spec Reference:


Implementation of E-UTRAN neighbor cell reporting via System Information 2 quater in OsmoBTS/OsmoBSC/OsmoNITB software including unit
tests and system test and fixing existing known SI2ter scheduling issues.

This includes
  • Verifying existing SI2ter is scheduled, use something like osmo-bts + gsmtap to see that it is scheduled at the right frame
  • bitvec for encoding the SI2 quater messages
  • Scheduling (segmented) SI2 quater messages in osmo-bts
  • VTY options to represent them. This is the most involved one so the actual interface and commands should be discussed.


  • Extending SI3 to indicate presence of SI2quater
  • Encoding of SI2quater messages with only the following optional parts (details see above):
    • Priority and E-UTRAN Parameters Description, containing
      • Serving Cell Priority Parameters Description
      • E-UTRAN Parameters Description, containing
        • Repeated E-UTRAN Neighbour Cells, with all their fields
        • Repeated E-UTRAN Not Allowed Cells, with all their fields
          • only implement the fixed single PCID (which can be repeated) encoding, not the bit-map / bit-masking encoding options
        • Repeated E-UTRAN PCID to TA mapping
  • Implementing "fragmentation" of SI2quater over multiple messages with their respective Index/Count fields
  • Sending SI2quater via A-bis RSL to the BTS
do not implement other elements, specifically not
  • "E-UTRAN Measurement Parameters Description"
  • "GPRS E-UTRAN Measurement Parameters Description"
  • "Extended EARFCNs" (EARFCN > 65535)
  • "MEASUREMENT INFORMATION" messages to instruct MS to provide measurement results for LTE while on GSM/GPRS
  • "Fast Acquisition" with UTRAN_Start/UTRAN_Stop


  • Fixing the existing SI2ter scheduling issues that may exist
  • Implement receiving SI2quater via A-bis RSL, taking into account there mgiht be multiple fragmented messages with index/count
  • Implement scheduling of SI2quater

Test Cases

  • Implement unit tests for SI2qater encoding in BSC (part of "make check")
  • Impement code that receives GSMTAP BCCH frames from OsmoBTS and verifies that only the correct expected SI messages occur at the right point in tme (FN / ...). This will be a separate program/tool, which hopefully we can later run together with osmo-bts-virtual as part of "make check", as the virtual BTS requires no real BTS hardware.


OsmoBTS - Feature #1631: implement SI2quater supportClosedmsuraev

Related issues

Related to OpenBSC - Feature #1660: segmented SI2quater supportClosed03/17/2016

Related to OpenBSC - Feature #1666: Implement UARFCN support for SI2quaterClosed03/22/2016


#1 Updated by laforge almost 5 years ago

feel free to create a child ticket in the OsmoBTS project to track the status of the BTS-specific parts.

#2 Updated by laforge almost 5 years ago

  • Due date set to 03/28/2016

#3 Updated by laforge almost 5 years ago

The SI2quater description can be found Chapter of TS 44.018 version 13.0.0 Release 13. Please use only this specifiation document/version, and not any other/older versions for reference.

#4 Updated by msuraev over 4 years ago

  • File si_check.gawk added
  • Status changed from New to In Progress

Attached is GNU Awk script which checks whether SI in a given .pcap are scheduled properly. Usage example is inside. Since script works with .csv as input it could be easily adopted later on to serve as part of "make check".

Using that script I've checked .pcap obtained via osmocom-bb's ./mobile app - no errors in 2ter (or any other) scheduling found so far.

#5 Updated by laforge over 4 years ago

#6 Updated by msuraev over 4 years ago

  • File deleted (si_check.gawk)

#7 Updated by msuraev over 4 years ago

Improved version of test script will be merged into osmo-bts/contrib.

#8 Updated by laforge over 4 years ago

  • Related to Feature #1666: Implement UARFCN support for SI2quater added

#9 Updated by laforge over 4 years ago

  • Status changed from In Progress to Closed

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