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O&M link problem with flexi 2g/3g

Viewing 5 posts - 1 through 5 (of 5 total)
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  • #66787

    Hello! I’ve been doing field repairs for the same operator for about 6 years now, and I’m facing the strangest problem so far. The problem started after thunderstorm some 2 weeks ago (our crew been very busy so we are still struggling with this one amidst all the other tasks on hand). Subjects are 2 nokia flexi sites. 2G multiradio and 3G flexi. I first got to the site with information that sites are “stuck”. So I got to the site and checked out both units with manager, everything seemed ok, no alarms, o&m up on both, all the links up with the 3G. Just that all the cells were inactive. Gave them both a reset (electricity). No radio-unit alarms whatsoever.
    After this everything got back to this exactly same situation. O&m up, links up etc… Called to the bsc and he told that he can’t get access to neither one of the sites.
    Allthough when he gave commands like reset to the 2g I saw that they came through, bsc just didn’t receive ack for those thus showing time out at the bsc side.
    Ok so, started to investigate this piece of marvelous imperfection!

    Some background information before I go on:

    Site is in middle of nowhere, rural area.
    Transmission for both sites (1xE1 for 2G and ethernet for 3G) comes through 2 radiolink hops, both are nsn flexi packets. And in the very last knot they go in ESS the ethernet and marconi sdh the 2mb.

    So, as the topic says, only thing that you can see is wrong on the site, is that the cnbap-link on the 3g (o&m?) and the o&m link on the 2G keeps disconnecting mostly every 1 minute, and sometimes lasts for a bit over 3 minutes, thus not giving the sites any chance to get on air. No alarms can be seen on the main view of the both managers! Only that the 3g switches between “integrated to ran” and “bts configured” – states. And when looking at the 2G event viewer you can see the o&m disconnecting with the mentioned times.
    Softwares are up to date, and I’ve re-comissioned both sites just to make sure, also the main unit and transmission cards have been replaced on BOTH sites, so no hardware can be the cause of this problem at the bts-side. Then, neither one of the flexipacket radio hops show any alarm or any other signs of fault, I’ve hard resetted them both to make sure. Also I measured the 2mb connection to the last point before BSC, from the first site before first radiolink hop, then before the second hop, and from the end where the bts’es are. No errors, no nothing during 10 minute samples. The 2mb stays happy as ever.

    So there we have it. The BSC is pretty much still thinking that the problem is somewhere on the field, but I’m losing my humour and keenness on this case. Strange is that the problem is exactly the same on the ethernet trs of the 3g site too.
    Next thing I’m thinking of doing is to set up the spare part – 2g multiradio with trs card to the first site where the trs comes, see if the same problem still occurs, and id it does, gonna throw the ball to the bsc. If it doesn’t,then there’s probably something consealed in those hops that keeps cutting the o&m.
    Hate thunderstorms… And the 2mb line was measured with a professional-grade dedicated meter, through active bts-bsc connection and agains a loop at the site, from the point before BSC. That’s about it! 🙂


    Hi JT,

    What a headache !
    I’m not a field engineer, but based on your description, it does look like a transmission issue on the last hop (between the last nsn flexipacket and the BTS). And issue seem to be in one direction only (from bts to bss) ?

    Good luck !


    I noticed that my post was perhaps a bit off-topic in this forum but anyway, thx for the reply, pix!
    The issue finally came to its solution. As I threatened, I took the nice and mobile test unit of one main unit+trs of flexi multiradio 2G to the first entry of the transmission route, right before the 2 flexi packet hops, and hooked “her” up there, and bang.
    Everything started to roll up nicely ane the device was ready to get “on air” in just few minutes, without a radio of course ;). No O&M disconnections were to be seen anymore!
    So next thing I took this babe behind the first flexipacket hop and the problem instantly occurred again!
    So, I gave all the equipment of the first hop ANOTHER electricity off/on treatment during this issue at hands, and that finally did the trick. Bsc connection started to work smoothly again and those strange o&m cutouts were goner! Took the spareparts-babe to the actual site and hooked her up to the original 2mb point and that was that. Also noticed that 3g was up and on the air too.

    So happy ending on this one… Stuff like this is always good to share anyway. Only thing wrong (repeating yeah I know) was the o&m connection with the 2g and the cnbap of the 3g. Other on 2mb and other on ethernet, which really makes this case a mystery. All the equipment satisfied, not alarming anything. Nothing was to be seen wrong with the 2mb measurements neither, just nothing.

    – J.T.



    short suspens, and happy ending: if you were a TV serie, you’d be terrible ! 😀

    so it was the transmission, as you thought.
    the fact that one was on ethernet and the other on e1 doesn’t matter since both are going through the same mw tunnel. So both were impacted in the same way.


    Bonjour. Bts flexi multiradio 2g. Oam disconecte. Bts commissioned .?

Viewing 5 posts - 1 through 5 (of 5 total)
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