Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

A deep dive into why Wi-Fi kind of sucks

arstechnica.com

Post reply on HN
Print view View original

181–190 of 242 posts

Re: A deep dive into why Wi-Fi kind of sucks

#181

Post by watersb »

douche wrote: post #86
bsenftner wrote: post #10

My day to day happiness quotient shot up the day I ditched my wireless wifi and ran Ethernet cables through my spaces. I'd realized I was constantly noticing wifi issues, and an apple mbp I use for email seems to drop wifi every half hour. But no longer, with them all wired up! Realizing there are USB3 to Ethernet gadgets really hits home how our modern technology is market-driven-dumb and anti-consumer: all modern l…

> all modern laptops don't even have Ethernet ports anymore! Surely things haven't gotten this insane outside the iFruitbasket? If so I'm going to have to stock up on upgradeable refurbished laptops...

For simple things, I actually love my HP Stream 11 laptop. Basically a ChromeBook sold with Windows. No Ethernet.

My kids' ChromeBooks don't have an Ethernet port. Good little Acer machines. School-issued CB, I have not been allowed to examine yet.

Re: A deep dive into why Wi-Fi kind of sucks

#182

Post by Sephr »

bbcbasic wrote: post #152
davidgerard wrote: post #38

My loved one went for a junior sysadmin job. They'd decided to remove all the wiring and use wifi for everything because of just the sorta hype mentioned here. Loved one pulled out a Palm Tungsten C and proceeded to crack all their WEP passwords there in the interview. Got the job too ... and the task of putting quite a bit of wiring back.

Lucky he/she didn't get arrested.

For what? Cracking passwords offline isn't illegal as long as you don't use the passwords to gain unauthorized access to a system and you don't share the password with anyone other than the rightful owners.

There's nothing wrong with cracking a WiFi network's WEP password in front of the owner of the network in order to demonstrate WEP's weak security. You would have to actually connect to the network to commit unauthorized access.

Re: A deep dive into why Wi-Fi kind of sucks

#183

Post by FabHK »

mseebach wrote: post #63
willidiots wrote: post #9

I build public Wi-Fi networks, you've probably used one of them. AMA if you have Wi-Fi questions. To say it "sucks" is a bit harsh. It's delivering multiple hundreds of Mbps to you via an unlicensed contention-based medium. The air interface is like sending packets over a noisy Ethernet hub; it's impressive it works as well as it does. That said, this article's a good primer on some of the protocol's fundamental chal…

Is there a good suite of tools to actually measure the quality of a wifi connection and/or surface, even help diagnose, problems?

On macOS, someone below recommended "WiFi Signal", USD 5.

Not so fully featured, I assume, but free is Wireless Diagnostics. Ignore the popup, and go to Windows -> Info/Scan/Performance (it's in System -> Library -> CoreServices -> Applications, but I start it via Spotlight)

Re: A deep dive into why Wi-Fi kind of sucks

#184

Post by watersb »

extra88 wrote: post #72
r1ch wrote: post #54

Lots of legacy tech is also one of the reasons why Wi-Fi sucks. If you do one thing today, disable 802.11b on your router. 802.11b beacons alone can completely jam a 2.4 GHz channel in dense deployments, exasperated by those ISPs that broadcast their own SSIDs from your home router. I wrote a more in depth blog about this at https://r1ch.net/blog/wifi-beacon-pollution

Huh, I have an older Airport Extreme, it doesn't look like I can disable 802.11b. I can't disable the 2.4GHz band either. Airports were never known for their configurability.

On my iPad right now. My first-generation "Time Capsule" has four options I can set via the iOS Airport Utility.

802.11n (b/g compatible) 802.11n only (2GHz) 802.11n (a compatible) 802.11n only (5GHz)

I gave away my AirPort a while ago, it was also first-gen of its kind so I think it only did 802.11a

Re: A deep dive into why Wi-Fi kind of sucks

#185

Post by matwood »

mhandley wrote: post #165
matwood wrote: post #146

I suggest reading up on how WIFI works and some of the problems like hidden nodes [1]. Sometimes I'm amazed WIFI works at all. [1] https://en.wikipedia.org/wiki/Hidden_node_problem

The classical hidden terminal problem, where two clients of the same AP can't receive each other and so collide when they transmit, isn't such a big deal with WiFi. First, there are, by definition, no hidden terminals for the downlink (and most traffic is downstream), or the clients couldn't associate with the AP. Second, although two clients can't receive each other's transmissions, if they're associated with the sa…

Thanks for the explanation. It's more evidence to my point that I'm always amazed it works at all :)

Re: A deep dive into why Wi-Fi kind of sucks

#186

Post by hchenji »

The article misses out on explaining WHY we cannot get the promised bitrates. The answer is Shannon's limit on channel capacity, which mandates that you pay in either bandwidth or high power or low noise (SNR) to get higher capacity. Now these WiFi devices have internal rate adaptation algorithms that choose a particular modulation and coding scheme (MCS) index based on the measured SNR. A higher MCS index means better higher bits per symbol (modulation) and lower overhead code rates, and more antennas (spatial streams), which is how you get the xx Gbps bandwidth advertised on the box. List of MCS indices: http://mcsindex.com/

In today's devices, interference is considered as noise, which means that SNR simply drops to a point where the higher MCS indices are not chosen at all. So, even though the device is capable of the advertised XX Gbps bitrate, the SNR isn't high enough to switch to those higher rates.

Re: A deep dive into why Wi-Fi kind of sucks

#187

Post by hchenji »

willidiots wrote: post #9

I build public Wi-Fi networks, you've probably used one of them. AMA if you have Wi-Fi questions. To say it "sucks" is a bit harsh. It's delivering multiple hundreds of Mbps to you via an unlicensed contention-based medium. The air interface is like sending packets over a noisy Ethernet hub; it's impressive it works as well as it does. That said, this article's a good primer on some of the protocol's fundamental chal…

802.11ax won't mean anything unless you reduce interference (see my reply below). Without high SNR, all these new efficiency techniques won't get you anything. Shannon capacity is still what limits performance.

Re: A deep dive into why Wi-Fi kind of sucks

#188

Post by yjftsjthsd-h »

epmaybe wrote: post #149
Groxx wrote: post #147

Earlier quoted context omitted.

Any idea why we do not have public, encrypted wifi? Seems like it should be easy / trivial to fix, and protects people from passive listeners.

Not sure what you mean by this. Https exists, no?

Sadly, https is pervasive but not universal.

Re: A deep dive into why Wi-Fi kind of sucks

#189

Post by ValentineC »

FabHK wrote: post #183
mseebach wrote: post #63

Earlier quoted context omitted.

Is there a good suite of tools to actually measure the quality of a wifi connection and/or surface, even help diagnose, problems?

On macOS, someone below recommended "WiFi Signal", USD 5. Not so fully featured, I assume, but free is Wireless Diagnostics. Ignore the popup, and go to Windows -> Info/Scan/Performance (it's in System -> Library -> CoreServices -> Applications, but I start it via Spotlight)

> Not so fully featured, I assume, but free is Wireless Diagnostics. Ignore the popup, and go to Windows -> Info/Scan/Performance (it's in System -> Library -> CoreServices -> Applications, but I start it via Spotlight)

Protip: it's also easily accessible by holding Option and clicking on the Wifi icon in the menu bar.

Re: A deep dive into why Wi-Fi kind of sucks

#190

Post by hchenji »

Klathmon wrote: post #151
digler999 wrote: post #150

Earlier quoted context omitted.

If they haven't done so already, maybe we'll see copper-clad drywall or flooring for such environments ? Guess that would take down cellular service too though.

I'm just waiting for a standard which smartly reduces transmit power so they all don't need to shout over each other.

Reducing transmit power reduces interference, but it also reduces capacity since the received power (and hence the SNR at the receiver) is reduced! The Shannon limit on channel capacity dictates exactly how much bit rate (C=B*log2(1+SNR)) is achievable over a channel. SNR is a fundamental ingredient of this equation.
Post reply on HN