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Author Topic: WiFi Range? An Explanation...  (Read 1166 times)

Larry N.

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WiFi Range? An Explanation...
« on: March 04, 2017, 08:14:17 AM »
I see a lot of posts related to getting more signal strength and/or longer range for WiFi, but it seems few people really understand a lot of the problems. This ARS Technica article covers a lot of ground and, though there is a bit of tech talk, a lot of it includes plain language that most folks can follow just fine. It'll help you understand not only home WiFi a bit better, but also why campground WiFi is so poor, even with strong signals.
Larry and Mary Ann N.
2016 Newmar Ventana 3709 -ISB6.7 XT 360HP
2015 Wrangler Sahara Unlimited toad
Formerly: Trailmanor 2720SL
  de N8GGG

Gary RV_Wizard

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Re: WiFi Range? An Explanation...
« Reply #1 on: March 04, 2017, 08:37:40 AM »
One point that many people miss is that seeing a good signal at your laptop or phone does NOT mean your end can transmit back reliably. The base station probably has a decent powered radio and maybe even some extra antennas scattered around, but your phone or computer with built in wifi has almost no antenna and a very limited power radio.  That's why a better grade wifi unit, externally mounted, will almost always do much better. Doubling or tripling the radio transmitter strength is a good start, and a higher antenna is a big help too.

As an analogy, think of an adult man playing catch with a small boy. The man can throw the ball a long way and easily reach the boy if he is standing 200 ft away, but the boy can only throw it back if he is maybe 40 ft away.
Gary
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Larry N.

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Re: WiFi Range? An Explanation...
« Reply #2 on: March 04, 2017, 09:37:43 AM »
Very true, Gary. That's an additional potential problem that, as you say, too few people understand. Radio theory/operations are far from intuitive.
Larry and Mary Ann N.
2016 Newmar Ventana 3709 -ISB6.7 XT 360HP
2015 Wrangler Sahara Unlimited toad
Formerly: Trailmanor 2720SL
  de N8GGG

John From Detroit

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Re: WiFi Range? An Explanation...
« Reply #3 on: March 04, 2017, 10:30:10 AM »
So, what the article says is "Salesmen inflate the ability of their devices so as to make them look better than the competition"...

Or as Murphy's law and other reasons why things go wrong says:
"Multiply all sales flyer's claims by 50%, and all salesmen's claims by another 50%"

I have measured 4,000,000 BYTES plus on a 5Ghz router.. That's the figure I trust. Since I measured it.

Of course this has nothing to do with range.. Range is  function of signal strength (Inverse square law applies) and ambient noise, either natural or man made (IE a router on an adjecent channel)   And "obstructions" between router and client.

5Ghz does not penetrate walls as well as 2.4 (or so I'm told) and yes, you can get 'high power" routers and clients, however there are federal limits (part 15 applies)  On ONE channel (Channel 1 on the 2.4 side) I am licensed for higher power (but have nothing that can do it) so experimenters doing that have scored connections miles apart.  But for the rest of us you are unlikely to do that.

You can improve your range however by modifying the antenna.. Two mods I have seen work well, or 3

One is a parabolic reflector that simpley Slips over the antenna on a Client (or router) with a "Sticks up like a finger" antenna... You print the design out on card stock, Cut it out (3 pieces) cover one of the cards with Aluminum foil and that's all folks . This will easily double your range.. google Open Roads Wi-Fi booster and I think you will find it (I stopped using one many years back)

The next one is found at amateurlogic.tv  Download Episode 3
You need a can of Welch's Grape Juice or .. Similur can (I used coffee)
I did NOT re-cut the antenna as George did.

The 3rd method is a much more recent (last year sometime I think) episode of Amateur Logic.. On this one he took his original "Can-tenna' (Ep-3) and mounted it on a Sattelite TV dish... Full instructions are in the video and related blog.

This method gives serious signal improvement and range improvement.

But then.. I've known for a long time your best investiment if you want more range is a better antenna.

Using Google Maps find Francisco road, Union City, MI
Now find 9 Mile and Southfield roads in Southfield MI
Now find the distance between them
My parents lived on Francisco
Channel 2, Detroit.. Southfield and 9 mile (Studio and transmitter)

We watched Channel 2
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Larry N.

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Re: WiFi Range? An Explanation...
« Reply #4 on: March 04, 2017, 11:50:15 AM »
Quote
So, what the article says is "Salesmen inflate the ability of their devices so as to make them look better than the competition"...

John, it says a lot more than that. It talks about the effects that interference (including noise and multipath) have on performance, along with the effects of many more stations on performance, even if they are neighbors and not part of "your" network. Perhaps I should have added "and Capacity" to the title...
Larry and Mary Ann N.
2016 Newmar Ventana 3709 -ISB6.7 XT 360HP
2015 Wrangler Sahara Unlimited toad
Formerly: Trailmanor 2720SL
  de N8GGG

prfcdoc

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Re: WiFi Range? An Explanation...
« Reply #5 on: March 04, 2017, 02:28:40 PM »
That was very interesting and helped me understand some things that I've always wondered about. Like when I got my first 5GHz/2.4GHz router in my large home I ended up on 2.4 the vast majority of the time because I couldn't get a signal in 5. It was unable to penetrate the walls and go the distance.
Bob
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8Muddypaws

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Re: WiFi Range? An Explanation...
« Reply #6 on: March 04, 2017, 02:49:31 PM »
Another way to get better signal out of a router you own is to install aftermarket firmware, DD-WRT, Tomato etc. and boosting the transmit power.  Be aware that this may shorten the life of the transmitter.

Channel contention - my experience is that nearly all routers will default to the busiest channel.  Use a free tool such as Incider (from www.majorgeeks.com) to discover all the networks around you (even the hidden ones) and what channels they are on.  Move yours to the least used channel(s).  This single trick usually results in a 30% increase in speed.

For example - The building I work in has 31 networks visible from my office.  12 of them are on channel 1, 10 on channel 6.  6 of the ones on channel 1 are high power industrial access points with a range measured in miles at full power, they are at 25% but still walking all over all the other networks.  People complain of slow wifi, and difficulty in joining the network.  When I ask them if they did a site survey before plugging in their router I usually get a deer in the headlights look. 
« Last Edit: March 04, 2017, 03:04:35 PM by 8Muddypaws »
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John From Detroit

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Re: WiFi Range? An Explanation...
« Reply #7 on: March 04, 2017, 06:51:46 PM »
Well yes Larry. I did also mention the adjecent (Or even same channel but I left that out) interference.

One of the things I do when setting up my network is log into the router, Give it a static address, then log into the Wi-Fi adapter "modem" and see what is out there.. Pick a channel as far from the park's router as I can get for my internal Wi-Fi.  IE: where I'm at now the park is, I think (Without checking) on channel 1 and I'm on 10.. or the other way around.
Nothing adds excitement like something that is none of your business
My Home is where I park it.

Lou Schneider

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Re: WiFi Range? An Explanation...
« Reply #8 on: March 04, 2017, 07:07:03 PM »
Another issue the article doesn't address is what's known as hidden transmitters and packet collisions. Wi-fi networks can only have one user at a time transmit on a channel so they handle multiple users by dividing time into very short slices and directing only one user at a time to transmit during that slice of time.   

If a computer wants to send data, it sends a brief burst to the access point requesting permission to send the data.  The access point hears this and sends a permission packet back.  The first computer then sends the data and waits for acknowledgement that it was received intact, or for a request to resend it.

Everyone else on the channel is supposed to remain silent while this process is underway.

When all of the networked PCs are in an office or other confined space, they can all hear each other and only one system at a time will transmit to the access point.   The other PCs hear the packet exchange and remain silent until it's completed.

In a setup like an RV park system, your computer can't hear transmissions directly from the other computers on the network because they're far enough apart that direct transmission from one PC to the other is blocked.  This lets more than one computer send a request to send at the same time, the packets collide and interfere with each other and the access point can't make sense out of either one.

Meanwhile, a third PC thinks the channel is idle and sends it's own request which is heard by the access point and receives permission to send it's data.  Instead of hearing the third PC sending it's data packet and staying silent until it's finished, the two original PCs think the channel is silent and resend their requests while the third PC is sending it's data.  All 3 packets collide and interfere with each other.  The access point is only aware of the third PC's activity and that it's data packet was corrupted, so it ignores the requests from the two interfering PCs and tells the third PC to try again.

All of these packet collisions and the need to resend data multiple times are what slows wi-fi throughput to a crawl, even though the Internet pipe feeding the system has sufficient bandwidth to handle everyone's needs.

By mounting your antenna higher than everyone else and increasing your transmitting power, you're letting your system blast through the interference.  You'll outshout the other users, your throughput will go up but it will be at the expense of drowning out everyone else trying to use the channel.
« Last Edit: March 04, 2017, 07:33:20 PM by Lou Schneider »

HappyWanderer

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Re: WiFi Range? An Explanation...
« Reply #9 on: March 04, 2017, 08:30:02 PM »
...  Use a free tool such as Incider (from www.majorgeeks.com) to discover all the networks around you (even the hidden ones) and what channels they are on. ...

Incider is no longer free, unless you can find a download site with an older version.
I don't have gray hair. I have wisdom highlights.

SargeW

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Re: WiFi Range? An Explanation...
« Reply #10 on: March 04, 2017, 10:04:19 PM »
Good article. However, a little more discussion on how to work around interference and collisions would have been nice.
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Tom

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Re: WiFi Range? An Explanation...
« Reply #11 on: March 06, 2017, 11:51:09 AM »
Some years ago, while visiting family in the olde country before cable internet came to their small village, I resorted to using a T-mobile 'air card' with my laptop. Couldn't figure out why I had zero signal and was unable to connect. Took the laptop out to the garden, and was immediately online. That's when I remembered that the walls of our son's home were 28" thick and made of stone  :o
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decaturbob

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Re: WiFi Range? An Explanation...
« Reply #12 on: March 06, 2017, 03:31:50 PM »
Im using a radio labs 48" marine antenna and their USB wijacker router the antenna plugs into.... which I then tie an Asus router set as an AP point. My connections so far have been impressive with this park's wifi system to the point we have no problem streaming netflix and being online at the same time with 2 laptops. My issues have been with subpar customer support with radiolabs where I have repeatedly requested any type of information on the wijack router..as they include zero manuals or offer even a pdf of the unit...

going on a week with outstanding signal. 
proud to have a 2008 Tioga 31M MH

BruceinFL

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Re: WiFi Range? An Explanation...
« Reply #13 on: March 06, 2017, 06:47:53 PM »
  Use a free tool such as Incider (from www.majorgeeks.com) to discover all the networks around you (even the hidden ones) and what channels they are on.  Move yours to the least used channel(s).  This single trick usually results in a 30% increase in speed.

I went to  majorgeeks and typed Incider into the search window. Nothing came up. Can you provide a link? Thanks.
Bruce A.
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2005 Ford F-350 SRW 6.0L

8Muddypaws

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Re: WiFi Range? An Explanation...
« Reply #14 on: March 06, 2017, 08:02:48 PM »
As someone already reported, incider no longer has a free version.  Give this one a try : 

http://www.majorgeeks.com/files/details/wiscan.html
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BruceinFL

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Re: WiFi Range? An Explanation...
« Reply #15 on: March 08, 2017, 09:29:43 PM »
As someone already reported, incider no longer has a free version.  Give this one a try : 

http://www.majorgeeks.com/files/details/wiscan.html

Thanks for the link. This is Windows only software. However, I think I found why I couldn't find the other software...it's called inSSIDer4 (the home user version) not Incider. This software is $19.95 but is available in both MAC and Windows versions.
Bruce A.
2004 Alpenlite Valhalla 29RK 5W
2005 Ford F-350 SRW 6.0L

8Muddypaws

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Re: WiFi Range? An Explanation...
« Reply #16 on: March 08, 2017, 11:31:02 PM »
I have memory leaks.
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aquadave

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Re: WiFi Range? An Explanation...
« Reply #17 on: March 18, 2017, 01:44:08 PM »
A couple suggestions #1 most mobile phone companies have Hotspot boxes they run up to 15 devices faster than connecting to your phone about $50 a month. I think Tmobile has a pre-paid that you juice up as you need it. These are your own plans and not bothered by other people using bandwidth. #2 get a dual antenna wireless router  leave 1 antenna alone and install an outside antenna to the other and mount it on your roof. The Hotspot are the future and way to go

 

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