GSM @ Camp 2011 preparations

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Konrad Meier meierk at informatik.uni-freiburg.de
Mon Jul 18 14:22:19 UTC 2011


Hi Harald,

On 16.07.2011 15:51, Harald Welte wrote:
>> We have two nanoBTS-Booster 1800 here at the university. If for some
>> reason the Ericsson RBS is not working it should be possible to lend
>> you the two bossters for the time of the camp. We also have a
>> splitter and combiner. I will test the splitter/combiner in
>> combination with a booster at the GPN end of this month.
>
> As it turns out, I have not yet managed to get the Motorola BTSs
> working, despite putting lots of time into it.  There are many reasons,
> but basically the Motorola BSS is _extremely_ different from normal GSM BSS
>
> So while I might still get it to work, I doubt it, and it would be
> better to pursue different plans now.
>
> We can certainly bring together a sufficient number of nanoBTS units to
> fill all our ARFCN.  The problem now is the coverage<->  capacity
> problem, i.e. I don't want 6 BTSs with small coverage area, but rather
> something like 2 or 3 sites (max) with each 2 or 3 BTSs.
>
> Have you meanwhile tested your splitter/combiner/booster setup?  does it
> work?

The original plan was to test the setup at the GPN. But stupid me forgot 
to order the RJ69 connectors :-(
Last week I was finally able to try the multi TRX setup with two 
nanoBTS, but without success. TRX 0 worked well but TRX 1 was not 
working for some reason. I think the problem is the initialization of 
TRX 1.
The nanoBTS are pretty new:
Equipment_Version='165g029_73'  Software_Version='168a352_v142b30d0'

Unfortunately I didn't had the time to investigate the issue further. 
Maybe tomorrow I have some time.

> What I can really easily re-use from the Motorola BTS are 2x hybrid
> combiner/duplexer units, i.e. something that has the following ports:
>
> * 1 antenna output, bidirectional, 7/16" socket
> * 2 PA Tx inputs, SMA
> * 1 Rx antenna output, N-type
>
> So if you don't have a similar setup, we could use those together with
> two nanoBTS with a Rx LNA and a Rx splitter.
>
> I have six of those hybrid combiner/duplexers.

I have two "SPLIT2P-SMA" from "Global Professional" [1]. My Idea was to 
use these two units with one naoBTS-Booster like shown here: [2]

Your idea sounds good too, but would require some RX LNA.

> I _might_ also get the Rx LNA + splitter of the Motorola BTSs to work,
> but those are less stand-alone and I'm not certain about it.
>
> What do you have in terms of antennas?

We have two omnidirectional antennas from PROCOM: CXL 1800-3
More information: [3]

> Also, when would you be able to provide the equipment to me?  I would
> want to put everything together + test it well ahead of the camp,
> probably around August 1st.

Ok, I will see what I can do.

Best regards
Konrad Meier

[1] http://www.globalprofessional.co.uk/acatalog/Splitter_mod.html
[2] http://lab.ks.uni-freiburg.de/attachments/download/260/setup.png
[3] 
http://www.procom.dk/eng/Page_menu/Products/Base_Station_Antennas/1.3_-_2.0_GHz/Omnidirectional_Antennas/CXL_1800-3




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