Hi dear osmocom folks,
I have been doing some bitrate throughput tests from different MS (i.e. phones models) connected to a working osmo-nitb/sgsn/ggsn configuration (with a nanoBTS DCS1800) and i get 15kbits/s maximum (tcp/udp transfer) with the gprs subnet nat-ed to a 100baseT lan connected to a 2Mbits/s dsl line
The channel configuration is as follow in the osmo-nitb configuration file :
<file /etc/osmocom/bsc.conf> (...) nominal power 23 max_power_red 0 rsl e1 tei 0 timeslot 0 phys_chan_config CCCH+SDCCH4 ! hopping enabled 0 timeslot 1 phys_chan_config TCH/F ! 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 PDCH
</file>
Should i change the channel configuration to get more bitrate ? Should add more cells (bts?) to add more channels ?
my best, cheers.
Xavier.
On Thu, Apr 26, 2012 at 08:23:20AM +0200, carcelle wrote:
Should i change the channel configuration to get more bitrate ?
you can increase the bitrate by adding more PDCH on other timeslots. You will lose those for voice, though. The nanoBTS is capable of dynamic TCH/F + PDCH switching, but we don't support that in OpenBSC yet.
Should add more cells (bts?) to add more channels ?
More BTSs (stand-alone) is not improving capacity, but you can increase coverage by putting them at different locations.
If you stack BTSs (multi-TRX), you can e.g. run the firs TRX with 7*PDCH and run the second TRX with TCH. This way you have maximum GPRS/EDGE bitrate, plus full set of voice channels.
Regards, Harald
Hi Harald,
thanks for your reply
On Thu, Apr 26, 2012 at 08:56:08AM +0200, Harald Welte wrote:
On Thu, Apr 26, 2012 at 08:23:20AM +0200, carcelle wrote:
Should i change the channel configuration to get more bitrate ?
you can increase the bitrate by adding more PDCH on other timeslots. You will lose those for voice, though. The nanoBTS is capable of dynamic TCH/F + PDCH switching, but we don't support that in OpenBSC yet.
ok understand, TCH/F + PDCH repartitions based on your how could i calcultate the theorical layer2/ip troughput available for one PDCH and correlate it to the troughput measured from the MS to an external IP ?
Should add more cells (bts?) to add more channels ?
More BTSs (stand-alone) is not improving capacity, but you can increase coverage by putting them at different locations.
If you stack BTSs (multi-TRX), you can e.g. run the firs TRX with 7*PDCH and run the second TRX with TCH. This way you have maximum GPRS/EDGE bitrate, plus full set of voice channels.
Excellent, i will work in this direction and let you know.
My best regards,
Xavier.
Regards, Harald --
- Harald Welte laforge@gnumonks.org http://laforge.gnumonks.org/
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Hi Xavier,
On Thu, Apr 26, 2012 at 12:22:16PM +0200, carcelle wrote:
you can increase the bitrate by adding more PDCH on other timeslots. You will lose those for voice, though. The nanoBTS is capable of dynamic TCH/F + PDCH switching, but we don't support that in OpenBSC yet.
ok understand, TCH/F + PDCH repartitions based on your how could i calcultate the theorical layer2/ip troughput available for one PDCH and correlate it to the troughput measured from the MS to an external IP ?
you can see the raw bitrates for different EDGE coding modes (PDCH coding scheme will vary depending on RF layer performance): https://en.wikipedia.org/wiki/Enhanced_Data_Rates_for_GSM_Evolution so it's 8.8 kbit/second / slot to 59 kbit/second /slot
For pure GPRS it's 8 kbit/second / slot to 20 kbit/second / slot
-
carcelle -
Harald Welte