Wi-Fi tethering bottleneck?

Question

Level 1

4 points

Wi-Fi tethering bottleneck?

Hi all,

Looking at getting a new Retina iPad Mini in the coming days, and need to decide on cellular vs. Wi-Fi.

Basically, I have unlimited 4G data that allows for tethering on my phone contract. I'm happy to tether the iPad to the phone if I'm not going to be hugely throttled by the connection between the two devices (Wi-Fi connection, Bluetooth is far too slow).

Does anyone know the bandwidth an iPhone offers to devices connected via Wi-Fi tethering?

I get ~60-70mbps 4G connection, so ~75mbps would be ideal between the iPhone and iPad. I know that the theoretical wireless N bandwidth is 300mbps+ but I can't imagine a little phone is going to achieve anywhere near that.

Cheers

Andy

iMac, OS X Mountain Lion, 27" i5, 2010

Posted on Feb 18, 2014 12:50 AM

Reply

Answer 1

Feb 18, 2014 1:07 AM in response to Andy9l

Hi Andy

I purchased exactly the same item this week, via John Lewis, (for the two-year free warranty). My thoughts on this are that whilst I like the iPad very much, it does have it's uses but my feeling is that it's a tad too big to me using as a cellular phone. I love my iPhone 5 and wouldn't wish to go to an iPad for making calls. Far too big. As for surfing the internet via a wireless carrier, I suspect that the costs would outweight the advantages. The thing is there are loads of wireless hook-up points up and down the country and you're never far away from a signal. Hope that's helpful.

Reply

Answer 2

Andy9l Author

Level 1

4 points

Feb 18, 2014 11:16 AM in response to Barry Wilbraham1

Hi Barry,

Thanks for the reply.

I wouldn't be using it as a phone, just using my 5s as a modem for the iPad. I'll be tethering my iPad using my iPhone wifi hotspot, but I want to know the bandwidth of the iPhone wifi hotspot to see if it'll be a bottleneck on the 4G data connection to the phone.

Basically:

4G --> iPhone --> Wifi hotspot --> iPad

I need the wifi hotspot piece of that chain to be faster than the 4G connection, otherwise it becomes worth my time getting the cellular model.

Data usage is not an issue. I get unlimited data that allows for any amount of tethering.

Through a number of discounts I'm eligible for, I will only be paying £140 for a new 64GB retina mini wifi, or £240 for one with cellular. I'd rather sink the £100 in something for my car though!

Cheers

Andy

Reply

Answer 3

ChrisJ4203

Level 10

230,371 points

Feb 18, 2014 11:38 AM in response to Andy9l

To be honest, as far as I know, the iPhone could not deliever any faster connection than it is receiving. It is receiving data at one rate, it cannot transfer it to your other device at a rate faster than it is getting it as. Cellular data speed is cellular data speed. Just because you are using it on a different device does not mean it is going to get faster.

Reply

Answer 4

Andy9l Author

Level 1

4 points

Feb 18, 2014 12:11 PM in response to ChrisJ4203

Hi Chris,

Yes, that's exactly what I mean.

I need the WiFi hotspot bandwidth to be greater or equal to 80mbps so that I don't get throttled by a slow iPhone -> iPad connection.

I want the 4G cellular connection to be the slowest point in the chain, NOT the WiFi hotspot.

Andy

Reply

Answer 5

ChrisJ4203

Level 10

230,371 points

Feb 18, 2014 4:47 PM in response to Andy9l

The wi-fi hotspot is being created by the phone. That is what tethering is all about. You are using the phone's cellular connection to create the hotspot.

Reply

Answer 6

Andy9l Author

Level 1

4 points

Feb 18, 2014 4:56 PM in response to ChrisJ4203

Indeed, I've been doing this for several years.

Basically, in networking, you always have a bottleneck. In most simple cases a network is only as fast as the slowest connection.

If my 4G connection is 80mbps, but the iPhone WiFi tether only offers 40mbps bandwidth to my iPad, then the bottleneck is the iPhone WiFi tethering since my iPhone cannot transfer the data at the same rate it's receiving it.

If the 4G connection is 80mbps, and the iPhone WiFi tether offers 150mbps bandwidth to my iPad, then the bottleneck is the 4G connection since the maximum rate at which my iPhone can transfer data is never reached.

The first situation is bad, the second is good. I was wondering if anyone knew the realistic WiFi bandwidth of an iPhone 5s tethering to a Retina iPad Mini.

Reply

Answer 7

Feb 18, 2014 5:02 PM in response to Andy9l

I think what Andy is asking is something along the lines of: "If my iPhone connection is 70mbps, will the iPad's speed be significantly less than 70 mbps while tethered to the iPhone?" In my experience with my iPad mini tethered to my iPhone 5 (CMDA LTE) there is a degradation in speed by about 10-20% (as measured by speedtest app). But of course, your mileage may vary ... and so does the app result (but it is always less than when I run it directly from the iPhone).

Also consider that a Wi-Fi only iPad does not have GPS, it relies on Wi-Fi networks in the vicinity to approximate your location. Even when tethered to my iPhone, my iPad does get location pretty good, but it seems to lag by several seconds to a few minutes, which means not good for in-car navigation (use the iPhone for that). An iPad with 4G capability will have true GPS (assisted by cellular location info) and is just as accurate and as quick as your iPhone in terms of acquiring and tracking your location.

Reply

Answer 8

ChrisJ4203

Level 10

230,371 points

Feb 18, 2014 5:18 PM in response to Andy9l

Evidently I have a misunderstanding of tethering, because if the phone is receiving 80mbps, how can you expect it to deliver 150mbps to the iPad?

Reply

Answer 9

Andy9l Author

Level 1

4 points

Feb 18, 2014 5:32 PM in response to rockmyplimsoul

Perfect rockmyplimsoul, exactly what I was after. I hadn't realised that the wifi iPads still didn't have gps in them - hadn't thought about it for a while. That may have persuaded me to get the cellular model.

@Chris, I think you're misunderstanding my question.

When tethering an iPad to an iPhone, there must be a certain maximum speed that data can be transferred between the two. If that maximum rate is faster than a 80mnps 4G connection, say, 150mbps, then I would be happy because I'd be getting full 80mbps 4G on my iPad through my iPhone.

If, however, the maximum rate is LESS than 80mbps, then my 4G connection is going to waste because the iPhone cannot keep up - it cannot transmit data to the iPad as quickly as it is receiving it.

I wanted to know what the data transfer rate between an iPhone and iPad is via WiFi tethering.

Reply

Answer 10

ChrisJ4203

Level 10

230,371 points

Feb 18, 2014 5:49 PM in response to Andy9l

Now I understand. You want to know the transfer rate. That I cannot answer, but it might be available on the spec page.

Reply

Answer 11

Courcoul

Level 6

18,558 points

Feb 18, 2014 8:45 PM in response to Andy9l

FWIW, did a test a little while ago. Got the i5 into 4G and enabled the hotspot. Then tethered the MBP and checked the link specs. Finally, ran SpeedTest on both devices, one after the other.

Results: the i5 hotspot is a non-impressive 802.11g flavor. Not a very big speed. Then, my carrier's 4G service süks big time, at least where I did the testing. But the speed results on both devices were consistent. My conclusion: wouldn't want to watch a 4K feed with this. HTH.

Reply

Answer 12

Andy9l Author

Level 1

4 points

Feb 19, 2014 12:20 AM in response to Courcoul

Exactly what I had feared. Although a link of 70mbit isn't a complete catastrophe as I'll be getting ~60mbps on average I think. In the UK, it's not going to get any faster any time soon. We have only just got 4G on reputable networks.

The question is, is a 10mbit speed loss worth another £15/month when I'm already at 65-75mbit for free? Probably not.

Also, GPS would be nice, you know - since it's 2014 and all. Can't believe they are sold without GPS these days!

Thanks for the info courcoul, really really useful.

Reply