Openbsc support for new BTS

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Jason DSouza Jason.DSouza at octasic.com
Tue Jan 21 12:51:41 UTC 2014


Hello Harald,
Thanks for your inputs.

On Fri, Jan 17, 2014 at 10:20 PM, Harald Welte <laforge at gnumonks.org> wrote:

>> During the configuration, openbsc takes quite a long time to configure all the physical timeslots. 
> I don't think there are any delays in the OpenBSC codes, at least not that I remember.  
> The OML configuration on the sysmoBTS or nanoBTS takes only seconds for a single TRX.

I investigated this in osmobts. The delay was exactly 20 seconds per physical ts, thus amounting around 160 seconds approx. The reason seems to be OML_PING_TIMER of 20 sec set after LINK_STATE_CONNECT in abis_timeout() function. I guess that's the polling time for the abis messages?

>> We see a lot of unexpected channels are configured 
> I suspect this is related to the fact that the RACH detection only has a very weak CRC, 
> which means that you get lots of false positives from the PHY.  Is that the case?

I do not think they are false positives from the phy, neither I think our CRC is weak. Those are mainly the rach from real commercial phones around.

> I would strongly argue against running any 'open' network outside a faraday cage.  
> So I believe you are doing it the 'right' way.
Of course yes! Auth policy in the config is always closed :)

> You can tune a lot of the parameters.  
> In osmo-bts code itself, you can set a threshold in terms of RxLevel or C/I 
> and drop all requests below a certain level or C/I

I need to check the support for those messages in our L1.

> In the system information, you can play with paramters such as Rx-Access-Level-Min.

The parameter rxlev access min <0-63> in the openbsc config takes care of this?
But again, this is measurement information I guess and need to be supported by the phy.

> Write access is permitted only via git-over-ssh, and we would need your ssh public key.  
> If you send that public key by private mail to me, I can autorize you to commit to the repository.

Ok I will do that in the separate email.

Thanks,
Jason




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