Shouldn't 3G speed be 3G speed regardless of the device?

January 6, 2011 6:21 AM

When do device capabilities determine 3G possibilities? I have two 3G devices, one is consistently nearly 2.5x faster than the other. Is this normal, or is something wrong?

I live in the country and do not have any hi-speed Internet access through cable or DSL.

About a year ago I bought a Blackberry that offered tethering and experienced hi-speed browsing from home. It was great. Late last Fall I upgraded to 3G Blackberry and the tethering was even faster.

A week ago I bought an AT&t MiFi, which is advertised as 3G. It's great. It creates a 3g wi-fi network in my home allowing the son with the Xmas ipod Touch to surf, text & download apps.

The 3g MiFi seemed so much faster that the 3G tethering on my laptop, so I ran a series of "modem speed tests," and sure enough. The Mifi unit is almost consistently 2.5 times faster in both uploads and downloads. (1.7Mb download & 1Mb upload average for the MiFi and .7Mb down and .4 up tethering).

Of course I called and without offering the results of my test asked the question "should the speeds be comparable?" Of course they would be I was told. When I offered the results of my test, I was then told that because the Mifi unit only does what it does, and the Blackberry does so much more like calendar, phone, apps, etc that the BB should not be expected to run as fast.

And that's what doesn't compute for me. Shouldn't 3G speed be 3G speed regardless of the device?

posted by bricksNmortar to technology (12 answers total)

"3G" doesn't refer to a specific technology. It refers to the "Third Generation" cellular data networks. So, if you're talking about two different carriers (AT&T and Verizon, for instance), their 3G speeds should not be compatible.

But, if you're using the same network for both, and tethering one, that's the deal right there.

If you tether a phone to your computer, you are limited by a couple of factors. 1) the CPU on the phone has to shuttle data from the cellular radio to the USB port, and back; 2) the maximum speed of USB 1 is only about 1Mbps.

So, combine the low throughput of USB with having to move the bits around in software with the CPU, and you can easily see that the speed is much, much lower than with a dedicated networking device.
posted by Netzapper at 6:33 AM on January 6, 2011

Netzapper is right- the BB isn't built for tethering speed, just the ability to do it.

I also *think* there might be an issue with all the data running up to their offices and then back again. Not sure, but I think so. When I tether with mine, some "smart" web pages think I am in Canada.

(Although I believe the newer Blackberries are USB2. Nonetheless, the Blackberry itself is the bottleneck.)
posted by gjc at 7:18 AM on January 6, 2011

Not all "3G" networks are the same, even on the same carrier. When I was in Raleigh, NC around 14 months ago the [AT&T] 3G was actually some newer faster thing (I think the term was 3.5G and/or HSDPA). My iPhone 3GS consistently got 2-3x faster speeds there while tethering (it's jailbroken) than I have anywhere else since.

So maybe that's what's going on here. Maybe your area has enhanced 3G and the Mifi supports it, but the Blackberry doesn't.
posted by buckaroo_benzai at 7:35 AM on January 6, 2011

As others have said, 3G is a category of technologies, not a specific implementation.

YMMV.
posted by blue_beetle at 7:49 AM on January 6, 2011

Right - consider 3G a marketing term at best, and definitely not a definition of download speed. This article about 4G specifications was an interesting read about what goes into a network naming conventions. Short answer - there are some technical differences, but the majority of what you hear when you buy a phone is pure advertisement messaging. The same is true of 3G, I'm sure.
posted by owls at 8:02 AM on January 6, 2011

Even among the same carrier, there may be different 3G technologies available - 1xRTT is 144 Kbit/sec, whereas EVDO rev A is over 20 times faster at 3.1 Mbit/sec max. Both are 3G technologies available on Sprint for example.

In short, "3G" is more of a marketing term than anything else, there is no such thing as "3G" speed.
posted by reptile at 8:46 AM on January 6, 2011

See also this. Nice story about how AT&T now has a 4G network because they decided to tell everyone that it's now a 4G network.

This one goes to 11.
posted by freakazoid at 9:01 AM on January 6, 2011

Man, even in T-Mobile, "3G" can mean HSPA or HSPA+, and the difference is significant, yet only a few of the phones support HSPA+.

They've actually addressed this by branding HSPA+ as their "4G", despite the technical convention requiring ABSURD speeds.

Personally, I think "4G" is stupidly technically defined in the several-hundred-Mbps range. That will be what we end up considering 5G.

2-6 Mbps = 3G
7-24 Mbps = 4G
7-50 Mbps = 4G/LTE

Note that none of those upper ranges are anywhere close to the 600+ Mbps mark that they're saying is really 4G.

Because of this branding schism and the differing nature of the technologies, you will be confused and you'll need to check specs on each individual device and network combination to see what you can realistically expect.

Finally, remember that all speeds are "theoretical" and will almost always be well below the advertised speed as coverage, signal quality, device antenna, and network overhead take those numbers down to about 50% of that in real world.

I'm hoping ITU just calls the 600+ stuff 5G instead of pretending that what we have now, which represents a several-hundred-percent increase on 3G, isn't 4G. 4G is what everyone refers to it as, not what ITU considers their technical specification.
posted by disillusioned at 1:30 PM on January 6, 2011

The MiFi uses HSDPA (if not, HSUPA) whereas your Blackberry doesn't.

HSDPA is faster than 3G for downlink offering theoretical speeds of 1.8Mbit/s, 3.6Mbit/s, 7.2Mbit/s and 14.4Mbit/s depending on the chipset used in the device. It's limited by a large number of factors including distance from the cell tower, the number of people sharing that tower and the maximum speed your network operator can handle.

HSUPA is pretty similar to HSDPA except that it has a greater uplink speed.

The fact that the MiFi is a dedicated device is a very minor factor. You might get a small speed drop as the Blackberry will attempt to use the data channel at the same time as your tethered laptop will - but that is about it. Also the MiFi uses USB 2.0 which means the bottleneck for speed will always be the network.

The TL;DR version, your Blackberry is 3G but your MiFi is 3.5G.
posted by mr_silver at 4:12 AM on January 7, 2011

I know this is going to get buried at the bottom, but I'm positive that Netzapper is wrong. The bus speed between the CPU and USB is more than adequate to shuttle data from the cellular radio to the USB port. I know Blackberry's are rubbish, but there is no way that an internal bus would run at 0.7Mbit/s, it would cripple the entire device.

Secondly all Blackberry's produced in (at least) the last four years have been USB 2.0 which has a realistic speed of 40Mbit/s. In all tethering/modem products that I've ever worked with, the limitation is always the mobile network speed and never the cable, USB port, CPU, baseband or WiFi.

If you provide the model number of the BB and the MiFi, I can prove my assertions.

(ex-USB modem Product Manager)
posted by mr_silver at 4:32 AM on January 7, 2011

mr_silver - The BB is the Torch 9800, the MiFi is the Novatel 2372.

Methinks you nailed it with regards to HSDPA. I did a little more research after posting yesterday and learned a lot more about 3G than I even knew existed.

Thanks all!
posted by bricksNmortar at 7:48 AM on January 7, 2011

Looking at the devices, I might actually be wrong :O

The Novatel MiFi 2372 has 7.2 Mbit/s download and 5.76 Mbit/s upload.

I cannot find specific technical specifications for the Torch as RIM seem reluctant to put this info in their "technical specification". A Google search doesn't yield much either (a label of "hsdpa: yes" isn't very helpful) but this site, which I've never heard of before, claims it is 7.2 Mbit/s download and 2.1 Mbit/s upload.

If that is correct, then there is something else causing the slow tethering speed. Probably the fact that the Blackberry is trying to split the bandwidth between the tethering and it's own usage.

However, if that site is wrong and really the Torch is 3.6Mbit/s with a lower upload speed (I can't think of what right off the top of my head right now), then taking into account that no-one ever gets those kinds of speeds, then it would explain the speed difference.
posted by mr_silver at 8:45 AM on January 7, 2011