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Bug #1671

Combined 850/1800 NITB not seen by Option Icon2 stick

Added by zecke about 2 years ago. Updated about 2 months ago.

Status:
Stalled
Priority:
Low
Assignee:
-
Category:
-
Target version:
-
Start date:
03/24/2016
Due date:
% Done:

0%

Spec Reference:

Description

When having a NITB with one GSM1800 BTS on ARFCN 877 and one on GSM850 on ARFCN 130 (that is not broadcasting), the Icon2 stick failed to join the network. When removing this cell (and hence the neighborcell information) it works immediately. The test was done with a nanoBTS.

Tests:

  • Make this stable, I had issued another AT+CFUN=0/CFUN=1 today morning and while I did this yesterday it is not a clear call
  • Test with sysmoBTS and the nanoBTS (e.g. maybe some SIs are not scheduled)
  • Look if all generated SIs are being sent
  • Look at the spec if such config is legal..
  • Look at the generated SIs

BTS 1 config

 bts 1
  type sysmobts
  band GSM850
  cell_identity 0
  location_area_code 1  
  base_station_id_code 63
  ms max power 15
  cell reselection hysteresis 4
  rxlev access min 0
  periodic location update 30
  radio-link-timeout 32 
  channel allocator ascending
  rach tx integer 9
  rach max transmission 7
  channel-descrption attach 1
  channel-descrption bs-pa-mfrms 5
  channel-descrption bs-ag-blks-res 1
  ip.access unit_id 1802 0
  oml ip.access stream_id 255 line 0
  neighbor-list mode automatic
  codec-support fr
  gprs mode none
  no force-combined-si
  trx 0
   rf_locked 0
   arfcn 130
   nominal power 23
   max_power_red 22
   rsl e1 tei 0
   timeslot 0
    phys_chan_config CCCH+SDCCH4
    hopping enabled 0
   timeslot 1
    phys_chan_config SDCCH8
    hopping enabled 0
   timeslot 2
    phys_chan_config TCH/F
    hopping enabled 0
   timeslot 3
    phys_chan_config TCH/F
    hopping enabled 0
   timeslot 4
    phys_chan_config TCH/F
    hopping enabled 0
   timeslot 5
    phys_chan_config TCH/F
    hopping enabled 0
   timeslot 6
    phys_chan_config TCH/F
    hopping enabled 0
   timeslot 7
    phys_chan_config TCH/F
    hopping enabled 0

History

#1 Updated by laforge about 2 years ago

I'm not even sure if a 850 + 1800 combination is legal at all. and even if it was legal as per the spec, I would assume that phone-side stack implementations likely are buggy, as it never happens in reality.

Either you're in the north-american region and then you have 850+1800, or you are in the rest of the world and have 900+1800.

It could be somtehing as simple as the Icon2 assuming that if a neighbor is announced by an 850MHz cell, it must be a 1900 MHz ARFCN, not an 1800 MHz one. Or the other way around, if an 850MHz ARFCN is announced in the neighbor list, it all must refer to 1900MHz? Or some other oddity along those lines.

Remember, the 1800 MHz and 1900 MHz band ARFCNs are overlapping in their numeric range.

#3 Updated by msuraev about 2 years ago

I could not find particular spec which covers it. In theory, 3-band phone for Brazil 850/1800/1900 might support it but not sure if at the same time. Shall we explicitly forbid such neighbor combinations in vty?

#4 Updated by msuraev 10 months ago

  • Status changed from New to Stalled

#5 Updated by laforge 6 months ago

  • Priority changed from Normal to Low

#6 Updated by msuraev 3 months ago

Should be re-tested with OsmoBSC.

#7 Updated by laforge about 2 months ago

  • Assignee deleted (msuraev)

#8 Updated by laforge about 2 months ago

  • Project changed from OpenBSC to OsmoNITB

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