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SNR to download speed on 3G/4G



 
 
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  #1  
Old December 18th 14, 10:51 AM posted to uk.telecom.mobile,uk.telecom.broadband
Martin Brown
external usenet poster
 
Posts: 343
Default SNR to download speed on 3G/4G

Hi,

Can anyone give me ballpark figures for how local SNR on a 3G or 4G
mobile data link maps to actual measured download speeds?

The fixed points I have are roughly

-70dB full speed (subject to contention ratio)

-90dB 1.5Mbps 3G Three Mifi Huawei

I plan on doing more experiments and sharing the results.

I reckon I can get an external aerial with +11dB gain so allowing for
injection losses a signal at the box of -80dB. I plan on doing the
experiment but I'd be interested in the range with different kit.
Recommendations would be very interesting as would kit to avoid.

My interest is in what speed I might hope to get with a signal level of
about -80dB and a high end 3G router with an external aerial. And also
will an "all you can eat" contract fall foul of streaming HD video?

Basically I am considering abandoning fixed line ADSL in favour of 3G
"mobile" but used from a fixed location. Some wet days the 1.5M Mifi can
be faster than the ADSL when junctions get wet and the line noisy. The
ADSL noise margin is stubbornly stuck at 16dB

Most of the time I get an ADSL sync around 3.6Mbps (lower in winter and
higher in summer). It is pretty ropey at the moment. Hell will freeze
over before we get SuperFast Broadband the best cherries have already
been picked and our village is simply too small to stand a chance.

--
Regards,
Martin Brown
  #2  
Old December 19th 14, 04:14 AM posted to uk.telecom.mobile,uk.telecom.broadband
Andy Burns[_2_]
external usenet poster
 
Posts: 210
Default SNR to download speed on 3G/4G

Martin Brown wrote:

Can anyone give me ballpark figures for how local SNR on a 3G or 4G
mobile data link maps to actual measured download speeds?


At home I get between -107dB and -111dB of LTE signal on O2, this
results in about 12Mbps down and 3Mbps up speeds. I'll try and remember
to read signal strengths in places where I know I get much faster speeds.


  #3  
Old December 19th 14, 09:26 PM posted to uk.telecom.mobile,uk.telecom.broadband
Graham J[_2_]
external usenet poster
 
Posts: 723
Default SNR to download speed on 3G/4G

Martin Brown wrote:
Hi,

Can anyone give me ballpark figures for how local SNR on a 3G or 4G
mobile data link maps to actual measured download speeds?

The fixed points I have are roughly

-70dB full speed (subject to contention ratio)

-90dB 1.5Mbps 3G Three Mifi Huawei

I plan on doing more experiments and sharing the results.

I reckon I can get an external aerial with +11dB gain so allowing for
injection losses a signal at the box of -80dB. I plan on doing the
experiment but I'd be interested in the range with different kit.
Recommendations would be very interesting as would kit to avoid.

My interest is in what speed I might hope to get with a signal level of
about -80dB and a high end 3G router with an external aerial. And also
will an "all you can eat" contract fall foul of streaming HD video?

Basically I am considering abandoning fixed line ADSL in favour of 3G
"mobile" but used from a fixed location. Some wet days the 1.5M Mifi can
be faster than the ADSL when junctions get wet and the line noisy. The
ADSL noise margin is stubbornly stuck at 16dB

Most of the time I get an ADSL sync around 3.6Mbps (lower in winter and
higher in summer). It is pretty ropey at the moment. Hell will freeze
over before we get SuperFast Broadband the best cherries have already
been picked and our village is simply too small to stand a chance.


In my experience 3G performance inside a building is useless.

I know of routers that accept a 3G dongle into a USB socket - and I can
see that one of these would work OK if the router and dongle were
mounted on the roof - but I can't see anybody putting a Vigor 2830 into
a waterproof box ...

What would be useful would be a waterproof 3G dongle with an Ethernet
port, and PoE; that way the dongle could easily be mounted where it
would receive a signal - up to 100 metres away from the router. Does
anybody know of such a device?

--
Graham J

  #4  
Old December 19th 14, 11:28 PM posted to uk.telecom.mobile,uk.telecom.broadband
alexd
external usenet poster
 
Posts: 1,765
Default SNR to download speed on 3G/4G

Graham J (for it is he) wrote:

What would be useful would be a waterproof 3G dongle with an Ethernet
port, and PoE; that way the dongle could easily be mounted where it
would receive a signal - up to 100 metres away from the router. Does
anybody know of such a device?


I think once it's got ethernet and PoE, we're out of dongle territory.
There's this:

http://www.3grouterstore.co.uk/3G/Te...4G-Router.html

although it's quite expensive.

This router has a USB and a miniPCIe slot so could take a 3G adaptor of
either type:

http://linitx.com/product/mikrotik-r...injector/13919

You might just be able to stuff a USB dongle inside the door [scroll down,
there's one with the door open:

http://proline.biz.ua/mikrotik-rb912uag-5hpnd-out

--
http://ale.cx/ (AIM:troffasky) )
22:31:57 up 53 days, 13:04, 5 users, load average: 0.81, 0.58, 0.54
Any sufficiently advanced incompetence is indistinguishable
from malice

  #5  
Old December 20th 14, 08:56 AM posted to uk.telecom.mobile,uk.telecom.broadband
Roland Perry
external usenet poster
 
Posts: 216
Default SNR to download speed on 3G/4G

In message , at 21:26:50 on Fri, 19 Dec
2014, Graham J remarked:
Most of the time I get an ADSL sync around 3.6Mbps (lower in winter and
higher in summer). It is pretty ropey at the moment. Hell will freeze
over before we get SuperFast Broadband the best cherries have already
been picked and our village is simply too small to stand a chance.


In my experience 3G performance inside a building is useless.

I know of routers that accept a 3G dongle into a USB socket


I have one of those and it's worked fine inside three different houses.
[Using 3 as the network]. Albeit in one of them I needed to put the
dongle near the window on a long USB extender cable.

- and I can see that one of these would work OK if the router and
dongle were mounted on the roof - but I can't see anybody putting a
Vigor 2830 into a waterproof box ...

What would be useful would be a waterproof 3G dongle with an Ethernet
port, and PoE; that way the dongle could easily be mounted where it
would receive a signal - up to 100 metres away from the router. Does
anybody know of such a device?


A better plan if the in-building coverage isn't up to it would be an
external aerial (possibly a directional one) and a dongle with an aerial
socket. I've got one of those too, plus an omnidirectional indoor aerial
which has helped on occasions when I've been getting poor in-train
coverage to my laptop.
--
Roland Perry
  #6  
Old December 20th 14, 09:31 AM posted to uk.telecom.mobile,uk.telecom.broadband
Martin Brown
external usenet poster
 
Posts: 343
Default SNR to download speed on 3G/4G

On 19/12/2014 21:26, Graham J wrote:
Martin Brown wrote:
Hi,

Can anyone give me ballpark figures for how local SNR on a 3G or 4G
mobile data link maps to actual measured download speeds?

The fixed points I have are roughly

-70dB full speed (subject to contention ratio)

-90dB 1.5Mbps 3G Three Mifi Huawei

I plan on doing more experiments and sharing the results.

I reckon I can get an external aerial with +11dB gain so allowing for
injection losses a signal at the box of -80dB. I plan on doing the
experiment but I'd be interested in the range with different kit.
Recommendations would be very interesting as would kit to avoid.


In my experience 3G performance inside a building is useless.


Strange. I can't measure much difference between signal level inside and
out provided I stick to rooms with a window in. Extra height gains me a
lot of signal as the local topography is significantly hilly.

I can also adjust which base station I can see in favour of a much
fainter remote -110dB one by standing in just the right place.

I lose a lot of signal in the core of the house. Some older walls are 3'
thick stone and they don't let much signal through at all.

I know of routers that accept a 3G dongle into a USB socket - and I can
see that one of these would work OK if the router and dongle were
mounted on the roof - but I can't see anybody putting a Vigor 2830 into
a waterproof box ...


ISTR Solwise do one. It would be nice if there was a cheap 3G dongle
with an external aerial socket but I don't know of one. You can get
radiative couplers for external aerials to dongles/Mifis but I am
sceptical of their efficacy. I am seriously marginal signal levels to
begin with so if I am to try this I need every last bit of SNR.

What would be useful would be a waterproof 3G dongle with an Ethernet
port, and PoE; that way the dongle could easily be mounted where it
would receive a signal - up to 100 metres away from the router. Does
anybody know of such a device?


http://www.solwise.co.uk/3g-routers.htm

But realistically you want a waterproof aerial on a longish lead and a
3G dongle with an aerial socket. I have perfected this trick for wifi
with a flat panel aerial which allows me to run my network out to 300m
from the base station in the direction I want it to go. Cheap Wifi
dongles with detachable aerials are much easier to come by.


--
Regards,
Martin Brown
  #7  
Old December 20th 14, 10:12 AM posted to uk.telecom.mobile,uk.telecom.broadband
Roland Perry
external usenet poster
 
Posts: 216
Default SNR to download speed on 3G/4G

In message , at 09:31:32 on Sat, 20 Dec
2014, Martin Brown remarked:
It would be nice if there was a cheap 3G dongle with an external aerial
socket but I don't know of one.


Huawei E160, loads of them on eBay.
--
Roland Perry
  #8  
Old December 20th 14, 11:33 AM posted to uk.telecom.broadband
grinch
external usenet poster
 
Posts: 68
Default SNR to download speed on 3G/4G

On 19/12/14 21:26, Graham J wrote:
Martin Brown wrote:
Hi,

Can anyone give me ballpark figures for how local SNR on a 3G or 4G
mobile data link maps to actual measured download speeds?

The fixed points I have are roughly

-70dB full speed (subject to contention ratio)

-90dB 1.5Mbps 3G Three Mifi Huawei



3g does not work like that if you are with the signal strength envelope
of your device you get full link speed. As you get towards the edge the
link struggles and drops so the throughput drops.

I work with cisco 887G they fall over at -90dBm but at -80dm you get
full link speed subject to the usual limitati9ons of a shared link.

They also support proper external antennas ,but it is
easier/better/cheaper to have a short antenna lead and longer Ethernet
rather than the other way round.

At -90dBm I am surprised it works at all, run wireshark and see if you
are getting lost of TCP retransmits






I plan on doing more experiments and sharing the results.

Most of the time I get an ADSL sync around 3.6Mbps (lower in winter and
higher in summer). It is pretty ropey at the moment. Hell will freeze
over before we get SuperFast Broadband the best cherries have already
been picked and our village is simply too small to stand a chance.


In my experience 3G performance inside a building is useless.

I know of routers that accept a 3G dongle into a USB socket - and I can
see that one of these would work OK if the router and dongle were
mounted on the roof - but I can't see anybody putting a Vigor 2830 into
a waterproof box ...

What would be useful would be a waterproof 3G dongle with an Ethernet
port, and PoE; that way the dongle could easily be mounted where it
would receive a signal - up to 100 metres away from the router. Does
anybody know of such a device?


  #9  
Old December 20th 14, 12:31 PM posted to uk.telecom.mobile,uk.telecom.broadband
[email protected]
external usenet poster
 
Posts: 83
Default SNR to download speed on 3G/4G

In uk.telecom.broadband Martin Brown wrote:
What would be useful would be a waterproof 3G dongle with an Ethernet
port, and PoE; that way the dongle could easily be mounted where it
would receive a signal - up to 100 metres away from the router. Does
anybody know of such a device?


http://www.solwise.co.uk/3g-routers.htm

But realistically you want a waterproof aerial on a longish lead and a
3G dongle with an aerial socket. I have perfected this trick for wifi
with a flat panel aerial which allows me to run my network out to 300m
from the base station in the direction I want it to go. Cheap Wifi
dongles with detachable aerials are much easier to come by.

Better than a WiFi dongle IMHO (... and yes, I know this is off the
original subject) are the TP-Link TL-WA7210N and similar devices
(there's a 5Ghz as well) which are outdoor housings with aerial and
everything inside powered by POE.

Aerial cables are lossy.

--
Chris Green

  #10  
Old December 20th 14, 01:09 PM posted to uk.telecom.broadband
The Natural Philosopher
external usenet poster
 
Posts: 2,728
Default SNR to download speed on 3G/4G

On 20/12/14 11:33, grinch wrote:
On 19/12/14 21:26, Graham J wrote:
Martin Brown wrote:
Hi,

Can anyone give me ballpark figures for how local SNR on a 3G or 4G
mobile data link maps to actual measured download speeds?

The fixed points I have are roughly

-70dB full speed (subject to contention ratio)

-90dB 1.5Mbps 3G Three Mifi Huawei



3g does not work like that if you are with the signal strength envelope
of your device you get full link speed. As you get towards the edge the
link struggles and drops so the throughput drops.


I think you will find that all radio spectrum comms is affected by who
else is on the channel.

Like old co-ax ethernet, there is contention and backoff on a busy link.
Ultimately Shannon/Nyquist gets you. Only so many bits per second for a
given bandwidth and power-to-noise. How those bits are shared amongst
competing devices and how close you can get to the maximum bps for the
channel bandwidth and noise is the black art of modulation schemes, but
you can't exceed those limits.

Depends what you mean by 'full link speed' of course.




--
Everything you read in newspapers is absolutely true, except for the
rare story of which you happen to have first-hand knowledge. - Erwin Knoll
 




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