Looking for a CSN.1 library

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OpenBSC implementation problem

how to know GPRS channel coding

Alexander Chemeris

21 Oct 2011 21 Oct '11

3:23 p.m.

Hi all, Does anyone know a good C/C++ library for CSN.1 bitstream reading/writing? We're working on a GPRS implementation for OpenBTS and we don't want to code all those RLC/MAC messages by hands when we can do this automatically. Right now we think that the easiest way is to re-purpose csn1 "library" from Wireshark - adopt it to OpenBTS bitstream operations and add support for writing to bitstream. Then we can even re-use those RLC/MAC messages already converted to macros' for Wireshark's rlcmac dissector. But we would appreciate if someone points us to a better way of doing this. -- Regards, Alexander Chemeris.

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Alex J Lennon

22 Oct 22 Oct

6:27 p.m.

New subject: Minor feedback on wiki build/installation instructions

Hi all, I've just started looking at OpenBSC with a nano-BTS I picked up. Thanks for the excellent OpenBSC build instructions on the web-site. I found I had to add in a couple of packages which might be worth adding in: libortp-dev, libortp8 (which I think -dev has a depency on anyway) NB. I'm using a vanilla Ubuntu dev. box, recently upgraded to oneiric Also the "make install" needed sudo prefixing but that's fairly minor I guess :) With those changes all built and installed painlessly. Now to test... Thanks & Best Regards, Alex Lennon Director Dynamic Devices Ltd http://www.dynamicdevices.co.uk

Harald Welte

23 Oct 23 Oct

10:12 a.m.

New subject: Minor feedback on wiki build/installation instructions

Hi Alex, On Sat, Oct 22, 2011 at 04:27:33PM +0100, Alex J Lennon wrote:

...

Thanks for the excellent OpenBSC build instructions on the web-site. I found I had to add in a couple of packages which might be worth adding in: libortp-dev, libortp8 (which I think -dev has a depency on anyway)

thanks for pointign this out. This is a relatively recent change required by libosmo-abis. I'm currently travelling without the required credentials, so if somebody else with wiki write permissions could take care of it, I would appreciate it.

...

Also the "make install" needed sudo prefixing but that's fairly minor I guess :)

well, it depends on what you have configured as prefix. If you use "--prefix /some/where/where/i/can/write" then it will install to that directory rather than the /usr/local/* where only root is normally permitted to write. Thanks for your positive feedback. It's good to see that some people actually find it easy and straight-forward - amang all the problem/bug reports we get ;) Regards, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

Alex J Lennon

26 Oct 26 Oct

1:16 p.m.

New subject: Question on characteristics of nano-BTS

Hi, I'm working through a UK Ofcom Non-operational license application form to obtain a license to test with an ip.access nano-BTS 1800. I'm having a little trouble determining a few of the characteristics of the nano-BTS and I wonder if anybody could offer me any advice? - Presumably I can provide GSM 1800 as the frequency of operation (or do I need to be more specific?). - What would be the "class of emission designation" for UK GSM ? - Given I'm just going to use a nano-BTS with a couple of Wifi 10dBi SMA antennae is there somewhere I can find figures for: - peak RF Power supplied to the antenna or load? - peak radiated power (ERP or EIRP) - mean radiated power (ERP or EIRP) Many thanks, Alex

Paul Dart

3:51 p.m.

New subject: Question on characteristics of nano-BTS

Hi, On 26 October 2011 11:16, Alex J Lennon <ajlennon(a)dynamicdevices.co.uk> wrote:

...

For the purposes of Ofcom this should be fine. They will then give you a set channel/freq. in that band to use and this will be specific.

...

- What would be the "class of emission designation" for UK GSM ? - Given I'm just going to use a nano-BTS with a couple of Wifi 10dBi SMA antennae is there somewhere

Wifi antennas are usually tuned for 2.4GHz and 5.8GHz (maybe 900MHz if you get it from the US or something). You are probably better getting an antenna that will work properly in the band you are using (unless it's a wideband antenna).

...

I can find figures for: - peak RF Power supplied to the antenna or load? - peak radiated power (ERP or EIRP) - mean radiated power (ERP or EIRP)

You need to know: a) the power output of the nanoBTS you have (ask the manufacturer/check the datasheet) b) any cable losses between that and the antenna c) the gain of the antenna (I presume 10dB is at 2.4GHz for wifi. It will likely be less for 1800MHz, see my comments above). Add these together and you will get the power out. a) and b) gives you the answer to the first one. ERP and EIRP are subtly different. Check wikipedia/ask Ofcom if you need some help.

...

Many thanks, Alex

Hope this helps, and good luck. Let me know if you do get an approved application as I would be interested in doing the same in the UK. Regards, Paul

Alex J Lennon

27 Oct 27 Oct

1:25 p.m.

New subject: Question on characteristics of nano-BTS

Thanks for your feedback on this Paul. I have had some more feedback from another chap who was also very helpful. I'll post it on this thread to assist anybody searching for this type of information in future. I will certainly let you know how the application proceeds. ... Yes you need to state 1800Mhz (class of emission) The BTS is a single-TRX BTS designed for indoor use (–5C to +45°C). Maximum transmit power is +23dBm for the 1800 MHz BTS Channel Spacing is 200Khz Power output control is 12 steps Power consumption is 13watts Standards are ETSI EN301489-9 Using the tool at http://www.compeng.com.au/emc_conversion_tables_power_calculator.aspx you should be able to work out what you require knowing the max output is +23db As a rough guide (as I'm NO radio expert) the formula is like so: EiRP (dBi)=ERP (dB)+2.1 ERP(dB)=Ant Gain (dBd)+POWERBTS (dBm)-Combiner loss-Cable loss-Fading margin So.... Output power = 23db Unit lose = 6.5db per 100m Gain of anntena = 10db Combiner lose = 3db Fading Margin = 2db Radiated power of attenna (ERP) = 21.5db (23 - 6.5 + 10 - 3 - 2) Max radiated power (EiRP) = 21.5 + 2.1 = 23.6dbi On 26/10/2011 13:51, Paul Dart wrote:

...

Hi, On 26 October 2011 11:16, Alex J Lennon<ajlennon(a)dynamicdevices.co.uk> wrote:

For the purposes of Ofcom this should be fine. They will then give you a set channel/freq. in that band to use and this will be specific.

- What would be the "class of emission designation" for UK GSM ? - Given I'm just going to use a nano-BTS with a couple of Wifi 10dBi SMA antennae is there somewhere

I can find figures for: - peak RF Power supplied to the antenna or load? - peak radiated power (ERP or EIRP) - mean radiated power (ERP or EIRP)

Many thanks, Alex

Hope this helps, and good luck. Let me know if you do get an approved application as I would be interested in doing the same in the UK. Regards, Paul

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Alex J Lennon
Alexander Chemeris
Harald Welte
Paul Dart