Kid is traveling in Europe, -90dB, what's the sensitivity Nexus 5

My daughter is traveling in Europe with the Google Nexus 5
and is getting a WiFi signal strength of -90dB using InSSIDer.

She can't connect to the WiFi at that signal strength.

I looked up the receiver sensitivity but can't find the spec:
http://www.phonearena.com/phones/Google-Nexus-5_id8148
http://www.phonearena.com/phones/Google-Nexus-5_id8148/fullspecs

Does anyone have the Nexus 5 receiver sensitivity spec?

 

I don't have a Nexus 5. It might be helpful to note that poor wi-fi
sensitivity seems to be a common problem with Lolipop (Android 5.0),
but which is now allegedly fixed:
<https://www.google.com/search?q=nexus+5+wifi+sensitivity>
Suggestions vary from rebooting the wi-fi by going in and out of
airplane mode, to rolling the phone back to Kitkat. Some hints.
<https://www.androidpit.com/improve-wi-fi-signal-on-android>

How far away is the access point that's producing the -90dB signal on
her phone? It might be too far away, or there may be too many
obstructions in the way.

 

It's about 60 feet away but through walls and I think it's just
attenuated. That's why every decibel counts.

If the sensitivity is, say, -98dBm, then she has 9 dB of headroom,
which isn't much but it might be enough.

I generally shoot for 10dB to 15dB of headroom on the SNR.
But it would be helpful if I could find the spec for the
Nexus 5 (all other radios provide the receiver sensitivity).

 

That's a fairly good reason for low signal levels, even if the Nexus 5
didn't have a wi-fi sensitivity problem. By "walls", I assume that
means 2 or more walls, which is usually enough at 60 feet to reduce
the signal level to near zero. I just tried it with my office router,
putting one wood wall (no foil backed insulation) and a concrete wall
between my router and my Nexus 7 tablet at 60 ft. One bar and many
disconnects. You might be expecting too much at 60ft.

The sensitivity of the receiver doesn't tell the whole story. I could
dig out the chipset used in the Nexus 5, try to find the
specifications, which usually require an NDA to obtain, the produce a
range of numbers depending on the connection speed and frequency (2.4
or 5GHz). However, I would also need to know the gain, orientation,
and location of the antenna in order to get the field strength
sensitivity. In other words, this is going to get complicated very
fast.

You're doing it the right way. Using SNR instead of signal strength
includes local noise and interference levels. These are important and
could also be a problem. If the Nexus 5 has a problem where "noise"
from the circuitry lands on 2.4 or 5GHz and trashes the receiver, it
might explain why the Nexus 5 seems to have a sensitivity problem. The
sensitivity might be there, but if the signal is buried in the noise,
the radio is not going to hear much.

Anyway, I don't think she has much of a chance getting the phone to
work at 60ft through 2 walls. Glass windows aren't much help these
days because they're all covered with Low-Emissivity coatings, which
block heat and RF, but pass light. Maybe finding a hot spot will
help. I suggest she grab WiFi Analyzer:
<https://play.google.com/store/apps/details?id=com.farproc.wifi.analyzer&hl=en>
and use the meter display to search the strongest signal.
<https://lh6.ggpht.com/bqclJIL4oQ3UB6aF0T17TzTjIjJMXF19xoLoHNDrcl8qoBjqPprYGQLG9kWj1ZEGIxY=h900>
The update rate (scan interval) can be tweaked down to about 2 seconds
(under Settings) making it practical for sniffing around for the
strongest signal.

Good luck.

 

Yes. They are solid walls. She doesn't know what they are made out
of (kids), but I told her to knock on them and she said they didn't
budge.

Yes but. It's a basic measurement. All radios have them.
They just don't seem to publish them for cell phones.
I'm surprised, because it matters MORE the weaker the equipment
is (so to speak).

And I know none of that, and she couldn't possibly either.

Yes. But. I'm guessing on the noise level of something like 95dBm or
thereabouts (just based on noise levels here at home).

I switched the T-Mobile plan this morning. Luckily they have a toll
free International number +1-505-998-3793 where she can ask them
for help.

They got her going on cellular data (she had roaming turned off)
and they showed her how to set up the "personal hot spot" so her
friend on AT&T could glom off her cellular signal.

It's only 3G but she was able to Skype with video today with me,
so, it's good enough for the most basic stuff.

T-Mobile said the new plan has unlimited data, but at 3G speeds
only (at best). They said roaming is free. And texting is free
and unlimited. The only thing that costs money is all phone calls
(whether to the USA or within the country) are 20cents per minute.

So, for now, since she can't get the WiFi going, she's OK; but
her friend, who is on AT&T (different plan) has only 800MB of
data before they start chargingher, and phone calls at 15 cents
per minute, free unlimited texting, but no personal hotspotting
(the friend is on an iPhone so it's dumber than the Android phone).

They both said they tried to go to a place that offered free
Internet but they said neither phone would connect. Since both
phones are "modern", I suspect they didn't know about a web
authentication or some other authentication process.

I told her about it, but I had put on InSSIDer long ago, when it
was still free (maybe two years ago when the Nexus 5 was new?)
so that's how she knew the decibels.

I just installed WiFi Analalyzer on my Android phone and it
is actually similar to InSSIDer, only it has ads. It has one
page for the graphs, another page for a signal strength
meter and beeper, and it shows the BSSID which is important
when you have multiple access points with the same SSID.

Overall, it seems like a nice 1:1 replacement for the otherwise
venerable InSSIDer which used to be freeware but which seems
to now be $10.

Thanks for the help! It's hot today where you are!

 

I did this graph in 2007 for various wi-fi routers based on the
manufacturers published wireless router sensitivity claims:
<http://802.11junk.com/jeffl/rx-sens/receiver sensitivity.htm>
The jump in sensitivity is the overlapping 802.11b to 802.11g
transition. The problem is that you can't really supply a single
number and claim that it's the "sensitivity". As near as I can tell,
these wireless router manufacturers simply used the numbers from the
chipset makers data sheets.

I've measured wi-fi sensitivity in the past. It's not easy and
requires some rather expensive test equipment, which I had to borrow
or rent. For measuring base line noise levels, disconnecting the
antenna in order to make a measurement is counterproductive as much of
the "noise" is coming from the handset via the antenna.

So, I invented my own crude test, which is good for comparisons, but
does not yield the numbers you seek. I fix the speed of the wireless
router to 802.11g 54 Mbits/sec. I start streaming video with UDP and
the smallest buffer size I can configure on the player. I then walk
away from the router until the streaming video starts to fall apart.
The transition point is very abrupt and quite obvious. The measured
range is a direct indication of the overall quality of the receiver
and antenna system. Unfortunately, there are a dozen other factors
involved, which prevent this method from becoming anything but a way
to compare the overall performance of two or more phones or devices.
Before I accuse a handset of having "poor wi-fi sensitivity" I compare
it with other handsets to see if it's really the handset or something
else.

The base line noise level depends on the local RF environment. Much
of the noise comes from the handset itself. The typical 802.11g
signal is about 25 MHz wide, or 5 wi-fi channels. If there are uses
on these adjacent channels, it will appear as noise to the receiver.
There are plenty of external sources of interference, that will add to
the noise level. However, the worst noise comes from the handset
itself. Digital circuitry generates noise, and the close proximity of
the digital noise source to the handsets wi-fi receiver insure that
the noise level is going to be rather high.

Can her friend with the iphone connect to the wi-fi router that's 60ft
away? If both phones have problems, it's a fairly good indication
that there's nothing wrong with her phone. Testing additional phones
in the same manner might also be useful.

Yeah, that happens. However, buggy wireless routers are also
amazingly common. The local coffee shop uses whatever is inside their
Comcast "gateway". Several of my devices will not connect while
others work normally. There are also ancient routers that have
problems dealing with hundreds of new connections each day. Some
hotspot owners turn down the tx power to prevent non-customers in the
parking lot from connecting. That works, but makes things difficult
for the customers inside the coffee shop.

Yes, but I'm near the ocean and spent the day in air-conditioned
comfort. When the sun went down, the fog rolled in, and it became
rather cold.

Incidentally, I've had to deal with a few Android phones where the
owner claims that the wi-fi "drops out" too often. Upon
interrogation, I usually find that it coincides with the phone going
into standby, where it switches back to cellular data. Leave the
wi-fi on full time and that problem will go away.
<http://www.androidcentral.com/android-101-save-battery-keeping-wifi-alive>

 

Interesting how the Ubiquiti lightstation was far better than all
the D-Link equipment, and that the sensitivity went down appreciably
by as much as 25 decibels over the speed range for the devices.

24 decibels would be 256 times less sensitivity at the higher
speeds! That's a lot!

That's interesting. So that's why the curves all dip at that one
point at around 10Mbps?

Yes, but that's a problem with *all* specifications.
We have to start with some kind of 'standard' sensitivity rating.

I guess the other option is to measure NOISE.
That wouldn't require fancy test equipment if the software can handle
it. I know WISP radios have the NOISE software built in, for example.

A physical drop is always a good thing to measure, and very clever.

This is a relatively large city, so, it's gonna be noisy.

Hmmmmmmm.... is that right? That's interesting. You'd think they have
that stuff filtered out.

The fact these kids are always together and one is on the crappy
iPhone virtually guarantees high noise then.

Nope. What they are doing now, since they don't have WiFi, is that
the iPhone user is on airplane mode and is glomming off my daughter
who was walked through how to set up a personal hotspot.

So, the T-Mobile Android personal hotspot is serving all the
WiFi for the two kids' needs using her cellular data connection
from T-Mobile (who says it's roaming with four companies).

Interesting tidbit to look out for. Thanks!