Cellular Network Infrastructure » Radio Access Network » OsmoBSC

OpenBSC is currently supporting the Site family of Nokia BTSes.

'''Things that work:'''

 - Nokia InSite and MetroSite units are proven to be working, UltraSite is probably working

 - Full Rate and Enhanced Full Rate voice calls (MO & MT)

 - SMS (MO & MT)

 - Cell reselection

 - Handover (please see this patch: [http://cgit.osmocom.org/openbsc/commit/?id=7d8fa3418ff6c589eba10e562da8b96995e19f7a] )

'''Handover:'''

The OpenBSC side of the handover logic works quiet well. But at the moment, there is a slight problem with the Nokia units. The handover decision is made correctly, the GSM phone is commanded to switch to the new channel on the new BTS, which the phone does. But despite the channel release is sent, the old channel never get released, and this leads to a Radio Link Failure.

Update: it seems that the root cause of the previous handover failure is that the InSite BTSes (probably others too) are not sending the channel release ACK to the BSC after the old channel release is requested by the BSC. Andreas Eversberg added a patch which overcomes this problem by implicating the missing ACK, so the BSC can continue and finish the handover process. This can be enbaled by adding the next line to the BTS part of the config file:

{{{

nokia_site no-local-rel-conf 1

}}}

This fix is tested on Nokia InSite and MetroSite units, all of them are performing handovers normally.

For more info, please see this patch: [http://cgit.osmocom.org/openbsc/commit/?id=7d8fa3418ff6c589eba10e562da8b96995e19f7a]

'''E1 cards:'''

The original Nokia support was written for HFC-E1 and mISDN. The Site can only be interfaced via traditional E1 lines (no IP ABIS support for these old units). It is also possible to use a DAHDI card to interface with the BTS. For this you have to use the following configuration in /etc/dahdi/system.conf:

{{{

span=1,0,0,ccs,hdb3,crc4	

bchan=1-31

}}}

Unlike in traditional E1 communication, we are using CCS signalling. For every signalling and traffic channel between the BTS and the BSC, we are using dedicated timeslots. Because of that, we are no longer need any shared signalling channel on the E1 line (e.g. D channel on timeslot 16.

'''Example config file for an 1800MHz Nokia InSite unit:'''

{{{

!

! OpenBSC configuration saved from vty

!   !

password foo

!

line vty

 no login

!

e1_input

 e1_line 0 driver dahdi

 # e1_line 0 port 0

 log file /root/900_nokia.log

 logging filter all 1

 logging color 1

 logging timestamp 1

network

 network country code 1

 mobile network code 1

 short name OpenBSC

 long name OpenBSC 

 neci 0

 rrlp mode none

 mm info 1

 handover 0

 handover window rxlev averaging 5

 handover window rxqual averaging 1

 handover window rxlev neighbor averaging 5

 handover power budget interval 6

 handover power budget hysteresis 3

 handover maximum distance 9999

 timer t3101 3

 timer t3103 5

 timer t3105 20

 timer t3107 10

 timer t3109 15

 timer t3111 2

 timer t3113 10

 timer t3115 0

 timer t3117 0

 timer t3119 0

 timer t3141 0

 timer t3122 10

 bts 0

  type nokia_site

  band GSM1800

  cell_identity 1

  location_area_code 1

  base_station_id_code 63

  training_sequence_code 7

  ms max power 12

  cell reselection hysteresis 4

  periodic location update 10

  nokia_site skip-reset 0

  nokia_site no-local-rel-conf 1

  oml e1 line 0 timeslot 8 sub-slot full

  oml e1 tei 1

  trx 0

   arfcn 885

   nominal power 18

   max_power_red 10

   rsl e1 line 0 timeslot 7 sub-slot full

   rsl e1 tei 1

    timeslot 0

     phys_chan_config CCCH+SDCCH4

     e1 line 0 timeslot 5 sub-slot 0

    timeslot 1

     phys_chan_config SDCCH8

     e1 line 0 timeslot 5 sub-slot 1

    timeslot 2

     phys_chan_config TCH/F

     e1 line 0 timeslot 5 sub-slot 2

    timeslot 3

     phys_chan_config TCH/F

     e1 line 0 timeslot 5 sub-slot 3

    timeslot 4

     phys_chan_config TCH/F

     e1 line 0 timeslot 6 sub-slot 0

    timeslot 5

     phys_chan_config TCH/F

     e1 line 0 timeslot 6 sub-slot 1

    timeslot 6

     phys_chan_config TCH/F

     e1 line 0 timeslot 6 sub-slot 2

    timeslot 7

     phys_chan_config TCH/F

     e1 line 0 timeslot 6 sub-slot 3

}}}

'''LMP cable pinout for InSite units:'''

'''LMP cable pinout for MetroSite units:'''

'''Tips and tricks for Site family and OpenBSC:'''