Problem with RBI 4G shifting between multiple towers

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nakedgeek

14 posts

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#205716 24-Nov-2016 09:35

I have just got 4G RBI and thought that I had a reasonably simple installation with 4.5k line of sight to a local cell tower. I purchased an external antenna (discussed here http://www.geekzone.co.nz/forums.asp?forumid=49&topicid=205138) and am in the process of trying different locations and directions to tune the signal.

The best signal I have been able to get so far is:

rsrq -11
rsrp -85
rssi -57

However the PCI (Cell ID) changes between two values and this dramatically affected speed tests and connectivity. Attempting to detune to get the 'best' tower sometimes picks up a third tower!

So it looks like I can 'see' 3 towers and the performance and reliability is dramatically different depending on which one I connect to. 2 towers are very close in terms of direction, a couple of degrees at most.

How can I find out which towers the PCIs identify so that I can know which one to aim for?

The PCI values are (Vodafone) 253, 256 and 258? (I suspect these are ARARIMU, HUNUA and KAIAUA but don't know which is which or how to find out)

And how can I make sure I only connect to a specific tower?

The antenna I am using is one of these: https://www.gowifi.co.nz/antennas-700-900-directional/ant-205.html - Are there more directional antenna so that I can aim more precisely? or are there less powerful antenna so that I connect to the closest site (which I think is what I want)

My main concern is that weather could tuning so that no matter what I do i might get shunted to another tower if it rains.

(Hoping that I can get this resolved otherwise I am stuck with sub 1mbps adsl that stops working when it rains)

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#1676578 24-Nov-2016 09:47

Who is the ISP?
I thought all RBI connections were professional installs with external antennas.

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nakedgeek

14 posts

Geek

#1676587 24-Nov-2016 10:07

ISP is Ultimate Broadband. They offer self install options.

Spark (not officially RBI, but pretty much the same) also do not supply or install an external antenna by default. When I inquired they suggested I put the modem by the window :)

My neighbour on Vodafone was offered an optional antenna installation at their own cost.

I guess it depends on how 'rural' the RBI installation is. I am in 'rural' Auckland, an area with very old and slow copper with no upgrade plans for decades, a dead zone as far as copper or fibre offerings are concerned but with reasonable 4G coverage.

Rikkitic

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#1676597 24-Nov-2016 10:21

I don't have a solution but I did have the same problem for awhile. I complained about it but my ISP was as mystified as me. Eventually it cleared up. I have no idea what was going on but it clearly wasn't at my end. At the time I was also having a lot of trouble with inconsistent and very slow speeds. My (uninformed) guess would be that this had something to do with the tower getting overloaded or suffering some kind of malfunction, which caused my gateway device to start looking for other connections. My ISP is not Vodafone, but they operate the towers used.

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nakedgeek

14 posts

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#1676683 24-Nov-2016 12:34

It turns out that two of the PCIs are actually from the same cell tower/site and so nothing can be done to stop the 'switching'

But that shouldn't mean such differences in performance and reliability. My ISP is going to talk to Vodafone to see if there is an issue there.

Also my signal readings are showing relatively high noise. Again this might be an issue with Vodafone.

Another thing learned is that, currently, VF don't provide a mechanism to lock service to a specific tower.

myfullflavour

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#1676690 24-Nov-2016 12:55

As far as I'm aware (and we're a Vodafone RBI wholesale customer) there is nothing that can be done about this.

It's a current industry bugbear.

coffeebaron

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#1676691 24-Nov-2016 12:56

Is it switching between 700 & 1800?

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nakedgeek

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#1676703 24-Nov-2016 13:09

@myfullflavour - in my case I am not actually switching towers, there are 3 PCIs at the same site. They should all perform the same though and don't seem to be.

But I can understand that there are situations where customers would want to lock onto a specific transmitter.

nakedgeek

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#1676708 24-Nov-2016 13:15

@coffeebaron - I didn't notice it switching frequencies but I was concentrating more on the signal values.

I've never noticed it connect to anything other than 4G 700 Band 28 but I will check again tonight.

And that would probably be another useful option: to be able to set the modem to 4G 700 specifically rather than 'prefer 4G' vs 'prefer 3G'

sbiddle

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#1676748 24-Nov-2016 15:34

nakedgeek:

@coffeebaron - I didn't notice it switching frequencies but I was concentrating more on the signal values.

I've never noticed it connect to anything other than 4G 700 Band 28 but I will check again tonight.

And that would probably be another useful option: to be able to set the modem to 4G 700 specifically rather than 'prefer 4G' vs 'prefer 3G'

Locking to a band would cause the same issues locking to a specific site would cause.

coffeebaron

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#1676938 24-Nov-2016 19:34

nakedgeek:

The PCI values are (Vodafone) 253, 256 and 258? (I suspect these are ARARIMU, HUNUA and KAIAUA but don't know which is which or how to find out)

253 Ararimu

256 & 258 Hunua

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nakedgeek

14 posts

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#1676988 24-Nov-2016 20:43

coffeebaron:
nakedgeek:

The PCI values are (Vodafone) 253, 256 and 258? (I suspect these are ARARIMU, HUNUA and KAIAUA but don't know which is which or how to find out)

253 Ararimu

256 & 258 Hunua

Thanks. so the switching is mainly between 256 & 258. 258 seems worse in terms of speed tests (half the speed of 256 and 'lumpy'). Both are extremely variable. I hope that reducing noise will improve things but i may be stuck with congestion :/

I can't make it switch to 1800. looks like it is always 700 regardless of which cell,

Am now waiting on my ISP/Vodafone.

coffeebaron

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#1677003 24-Nov-2016 21:02

Looks like your on the cusp of two sectors. Perhaps try antenna on other side of house shielded from Hunua and aim for Ararimu.

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nakedgeek

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#1677044 24-Nov-2016 21:55

coffeebaron: Looks like your on the cusp of two sectors. Perhaps try antenna on other side of house shielded from Hunua and aim for Ararimu.

Can't think why my neighbour isn't in the same boat as my antenna fires straight over his house.

The couple of tests I've done against Ararimu haven't been promising but I'll try again at the weekend.

In the meantime I'll wait and see what VF come back with.

raytaylor

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#1677157 25-Nov-2016 08:17

What happens if you take the antenna off and just use the internal antenna of the modem?

You can position the modem in the window and run ethernet cabling to another modem that can provide the wifi.

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coffeebaron

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#1677158 25-Nov-2016 08:22

Also try mount antenna on a 45 degree angle, or use two antennas

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