State of Frequency Hopping in OpenBSC

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Harald Welte laforge at gnumonks.org
Sun Jun 20 14:08:25 UTC 2010


Hi!

I've now merged the 'laforge/hopping' branch to master, and wanted to update
you on the state of frequency hopping support:

First, the bad news: It is still not working with the BS-11 :(

All OML attributes that I can think of are set correctly, they have been
verified from wireshark, and the BTS acknowledges all those attributes. 

On RSL, the channels are activated the right way, and even the SYSTEM
INFORMATIO 1 (cell channel allocation) as well as the chennel description and
mobile allocation parts of the IMMEDIATE ASSIGN are encoded correctly.

Still, the MS and BTS fail to establish any hopping channel.  Dieter is now
trying to get the BS-11 hopping configuration working with his Racal 6113.
If that works, the protocol trace should reveal where we still do something
wrong.

If you want to play with it:  The BTS attributes as well as the TRX attributes
are not yet 100% finished like they should be.  So you need to apply the
attached patch as a hack on top of master.  Please note that the
bs11_attr_radio_trx1 contains hard-coded ARFCN 117 and 119, i.e. you will
have to modify this unless your hopping sequence also only consists of those
two ARFCN.

I've also attached a config file for your reference.

-- 
- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
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!
! OpenBSC (0.9.0.845-57c4) configuration saved from vty
!!
password foo
!
line vty
 no login
!
network
 network country code 1
 mobile network code 1
 short name OpenBSC
 long name OpenBSC
 auth policy closed
 location updating reject cause 13
 encryption a5 0
 neci 0
 rrlp mode none
 mm info 0
 handover 0
 handover window rxlev averaging 10
 handover window rxqual averaging 1
 handover window rxlev neighbor averaging 10
 handover power budget interval 6
 handover power budget hysteresis 3
 handover maximum distance 9999
 timer t3101 10
 timer t3103 0
 timer t3105 0
 timer t3107 0
 timer t3109 0
 timer t3111 0
 timer t3113 60
 timer t3115 0
 timer t3117 0
 timer t3119 0
 timer t3141 0
 bts 0
  type bs11
  band GSM900
  cell_identity 0
  location_area_code 1
  training_sequence_code 7
  base_station_id_code 63
  ms max power 15
  cell reselection hysteresis 4
  rxlev access min 0
  channel allocator descending
  rach tx integer 9
  rach max transmission 7
  oml e1 line 0 timeslot 1 sub-slot full
  oml e1 tei 25
  gprs mode none
  trx 0
   rf_locked 0
   arfcn 121
   nominal power 24
   max_power_red 12
   rsl e1 line 0 timeslot 1 sub-slot full
   rsl e1 tei 1
    timeslot 0
     phys_chan_config CCCH
     hopping enabled 0
     e1 line 0 timeslot 1 sub-slot full
    timeslot 1
     phys_chan_config TCH/F
     hopping enabled 0
     e1 line 0 timeslot 2 sub-slot 1
    timeslot 2
     phys_chan_config TCH/F
     hopping enabled 0
     e1 line 0 timeslot 2 sub-slot 2
    timeslot 3
     phys_chan_config TCH/F
     hopping enabled 0
     e1 line 0 timeslot 2 sub-slot 3
    timeslot 4
     phys_chan_config TCH/F
     hopping enabled 0
     e1 line 0 timeslot 3 sub-slot 0
    timeslot 5
     phys_chan_config TCH/F
     hopping enabled 0
     e1 line 0 timeslot 3 sub-slot 1
    timeslot 6
     phys_chan_config TCH/F
     hopping enabled 0
     e1 line 0 timeslot 3 sub-slot 2
    timeslot 7
     phys_chan_config TCH/F
     hopping enabled 0
     e1 line 0 timeslot 3 sub-slot 3
  trx 1
   rf_locked 0
   arfcn 119
   nominal power 24
   max_power_red 12
   rsl e1 line 0 timeslot 1 sub-slot full
   rsl e1 tei 2
    timeslot 0
     phys_chan_config SDCCH8
     hopping enabled 1
     hopping sequence-number 0
     hopping maio 0
     hopping arfcn add 117
     hopping arfcn add 119
    timeslot 1
     phys_chan_config TCH/F
     hopping enabled 1
     hopping sequence-number 0
     hopping maio 0
     hopping arfcn add 117
     hopping arfcn add 119
     e1 line 0 timeslot 4 sub-slot 1
    timeslot 2
     phys_chan_config TCH/F
     hopping enabled 1
     hopping sequence-number 0
     hopping maio 0
     hopping arfcn add 117
     hopping arfcn add 119
     e1 line 0 timeslot 4 sub-slot 2
    timeslot 3
     phys_chan_config TCH/F
     hopping enabled 1
     hopping sequence-number 0
     hopping maio 0
     hopping arfcn add 117
     hopping arfcn add 119
     e1 line 0 timeslot 4 sub-slot 3
    timeslot 4
     phys_chan_config TCH/F
     hopping enabled 1
     hopping sequence-number 0
     hopping maio 0
     hopping arfcn add 117
     hopping arfcn add 119
     e1 line 0 timeslot 5 sub-slot 0
    timeslot 5
     phys_chan_config TCH/F
     hopping enabled 1
     hopping sequence-number 0
     hopping maio 0
     hopping arfcn add 117
     hopping arfcn add 119
     e1 line 0 timeslot 5 sub-slot 1
    timeslot 6
     phys_chan_config TCH/F
     hopping enabled 1
     hopping sequence-number 0
     hopping maio 0
     hopping arfcn add 117
     hopping arfcn add 119
     e1 line 0 timeslot 5 sub-slot 2
    timeslot 7
     phys_chan_config TCH/F
     hopping enabled 1
     hopping sequence-number 0
     hopping maio 0
     hopping arfcn add 117
     hopping arfcn add 119
     e1 line 0 timeslot 5 sub-slot 3


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