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:

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Does anyone have the Nexus 5 receiver sensitivity spec?

Reply to
Paul B. Andersen
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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: Suggestions vary from rebooting the wi-fi by going in and out of airplane mode, to rolling the phone back to Kitkat. Some hints.

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.

Reply to
Jeff Liebermann

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).

Reply to
Paul B. Andersen

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: and use the meter display to search the strongest signal. 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.

Reply to
Jeff Liebermann

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!

Reply to
Paul B. Andersen

I did this graph in 2007 for various wi-fi routers based on the manufacturers published wireless router sensitivity claims: 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.

Reply to
Jeff Liebermann

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!

Reply to
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