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iPhone 3GS Upstream Transfers Limited to 384 Kbps

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Macworld reports that while the iPhone 3GS does support the improved 7.2 Mbps download transfer speed now currently being deployed in the U.S. by AT&T and already available in other parts of the world, it will not support the correspondingly improved upload transfer speeds of 1.4 or 1.9 Mbps generally available on such networks and will be limited to the same 384 Kbps upload speed available on the iPhone 3G.
I had supposed that Apple took the opportunity to build HSUPA on the upstream side, at either 1.4 or 1.9 Mbps speeds that are supported in many European networks that have already rolled out 7.2 Mbps HSDPA. But it turns out, Apple didn't. . .

After my HSPA article ran, reader Nick Dunklee pointed out in e-mail that a teardown at RapidRepair of an iPhone 3GS shows that it has a UMTS/HSDPA chip. UMTS is the earliest 3G standard deployed on GSM networks, and it tops out at 384 Kbps. It's easy to test, if you have an iPhone 3GS. Go to any speed tester, like Testmyiphone when you're outdoors with a good signal. Downstream, you might hit well over 1 Mbps; upstream, under 384 Kbps.
Macworld's report is a follow-up to a previous article that discussed the ins and outs of the High Speed Packet Access (HSPA) network standard and how AT&T's offerings compare to that standard.
HSPA (High Speed Packet Access) is actually two separate standards: HSDPA (for downstream) at a raw rate of 7.2 Mbps and HSUPA (for upstream), likely at raw rates of 1.4 Mbps or 1.9 Mpbs, the two most popular upload speeds deployed by existing 7.2 HSPA carriers. The 7.2 Mbps downstream and 1.4/1.9 Mbps upstream rates represent the full bandwidth available in a given HSPA channel, but don't translate to what an individual user will see.

For AT&T's current HSPA system, the company claims range from 700 Kbps to 1.7 Mbps downstream, and 500 Kbps to 1.2 Mbps upstream.
So while the iPhone 3G was unable to even take full advantage of existing upstream transfer speeds, the iPhone 3GS suffers from the same limitation. But the limitation is not unique to the iPhone, as the new report mentions that other GSM smartphones are also utilizing the older UMTS standard at a maximum of 384 Kbps.
Dunklee examined the specs on a number of GSM network smartphones, and found none included HSUPA. It's possible that there could be a firmware update from UMTS to HSUPA, but that’s unlikely. There's usually a reason for using an older standard, which is related to power consumption, chip size, or cost.
Smartphones using competing CDMA technology, such as those on Sprint and Verizon, however, do take advantage of the full upstream capacity, suggesting that the limitation is related to the use of GSM technology as the basis for these cellular networks.

Article Link: iPhone 3GS Upstream Transfers Limited to 384 Kbps
 

thegoldenmackid

macrumors 604
Dec 29, 2006
7,770
5
dallas, texas
I can't imagine it would make a significant difference to most if it was limited even at 600kpbs, after all most users are satisfied with 160kpbs.
 
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kdarling

macrumors P6
The problem, as others have pointed out, is that poor upstream bandwidth limits the ACKs going back... thus potentially limiting the downstream speed, especially for TCP/IP.

There are about a gazillion papers (and a few Internet RFCs) about the ack problem with unequal bandwidths.
 
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aardwolf

macrumors 6502
May 30, 2007
366
135
Standard broadband from Comcast here in the Memphis metropolitan area tops out at 384kbps upload. Most people have no idea their "10Mbps" isn't both ways. I seriously doubt most people would notice a speed bump on their upload either... unless they're constantly uploading things.

I have my own web server, so I went with local DSL and am enjoying 3Mbps upload.
 
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Diode

macrumors 68020
Apr 15, 2004
2,426
96
Washington DC
Standard broadband from Comcast here in the Memphis metropolitan area tops out at 384kbps upload. Most people have no idea their "10Mbps" isn't both ways. I seriously doubt most people would notice a speed bump on their upload either... unless they're constantly uploading things.

I have my own web server, so I went with local DSL and am enjoying 3Mbps upload.

Well here in DC and most of the NE you can get Verizon Fios with 25/25 for a reasonable rate (like 64/month) or even 50/25.

100 synchronous is already offered in some parts of the country.

I would say "most people" would be a poor statement. Not to mention this becomes a further problem when AT&T begins allowing tethering.
 
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ibwb

macrumors regular
Mar 7, 2006
170
21
The problem, as others have pointed out, is that poor upstream bandwidth limits the ACKs going back... thus potentially limiting the downstream speed, especially for TCP/IP.

There are about a gazillion papers (and a few Internet RFCs) about the ack problem with unequal bandwidths.

Ack bandwidth is important but you don't need equal upstream to your downstream to send out acks. Maybe more like 10%.
 
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aardwolf

macrumors 6502
May 30, 2007
366
135
Well here in DC and most of the NE you can get Verizon Fios with 25/25 for a reasonable rate (like 64/month) or even 50/25.

100 synchronous is already offered in some parts of the country.

I would say "most people" would be a poor statement. Not to mention this becomes a further problem when AT&T begins allowing tethering.

Let me qualify that by saying "most people in this area".
 
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str1f3

macrumors 68000
Aug 24, 2008
1,859
0
All this means to me is another reason for the iPhone to be on Verizon. I can't believe this is not a Page 1 story.
 
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MovieCutter

macrumors 68040
May 3, 2005
3,342
2
Washington, DC
Well here in DC and most of the NE you can get Verizon Fios with 25/25 for a reasonable rate (like 64/month) or even 50/25.

100 synchronous is already offered in some parts of the country.

I would say "most people" would be a poor statement. Not to mention this becomes a further problem when AT&T begins allowing tethering.

Where the heck in DC can you get Fios? It sure as hell isn't DC Metro.
 
Comment

Shasterball

macrumors 6502a
Oct 19, 2007
878
56
glad I will be not getting a new iPhone till the next upgrade

And then we will all complain about [fill in future complaint here].

The truth is, I have the 3GS and it is crazy fast. Most users won't notice the difference. Plus, with new, graphics intensive games/apps coming out, it's nice to have the extra horse power (CPU-wise).
 
Comment

aperry

macrumors 6502a
Jul 12, 2008
600
33
For non-jailbroken phones this will only really affect tethering. And even within the realm of tethering it would only affect you if you need to host a website, use bit torrent, or upload and/or email large files somewhere.

That said, I'd be disappointed to be paying an arm and a leg for tethering only to have handicaps like this applied.
 
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djellison

macrumors 68020
Feb 2, 2007
2,229
4
Pasadena CA
I've only found one place in the entire UK where 3G even threatens to get that fast, and that's central London. A total irrelevance.
 
Comment

juice

macrumors newbie
Sep 27, 2007
23
0
Where the heck in DC can you get Fios? It sure as hell isn't DC Metro.

Uh... you can get it pretty much everywhere. I have it in Arlington, know people with it in Reston, Great Falls, McLean, Chantilly, Fairfax.... pretty much everywhere now.
 
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aendaman

macrumors member
May 28, 2008
57
0
lame to the max

yeah thats really lame! i could not believe it when they were talking about uploading video content to youtube or whatever and later when i checked i could not find any HSUPA capable chip in the iphone specs.
i just did a quick estimation that a one minute video would take ten minutes to upload at that UMTS speed of ~50KByte/s... wtf?
not to mention internet tethering... thats when you would probably like to quickly email a X MB powerpoint/pdf file from on the road.
and dont tell me HSUPA will drain battery significantly more than HSDPA.

that said, i will get a 3gs this october :rolleyes:
just sad because where i live, t-mobile has great coverage for both HSDPA and HSUPA...
 
Comment

Diode

macrumors 68020
Apr 15, 2004
2,426
96
Washington DC
Where the heck in DC can you get Fios? It sure as hell isn't DC Metro.

FIOS is available in DC at a few Apartments in the Capitol Riverfront area. More areas will be available by the end of the year.

Most of DC metro (outside of the District itself) already has it.

Comcast already offers 50mbps in DC anyways so the bickering of in dc/out of dc is moot.
 
Comment

aristotle

macrumors 68000
Mar 13, 2007
1,768
5
Canada
yeah thats really lame! i could not believe it when they were talking about uploading video content to youtube or whatever and later when i checked i could not find any HSUPA capable chip in the iphone specs.
i just did a quick estimation that a one minute video would take ten minutes to upload at that UMTS speed of ~50KByte/s... wtf?
not to mention internet tethering... thats when you would probably like to quickly email a X MB powerpoint/pdf file from on the road.
and dont tell me HSUPA will drain battery significantly more than HSDPA.

that said, i will get a 3gs this october :rolleyes:
just sad because where i live, t-mobile has great coverage for both HSDPA and HSUPA...
You might want to look at the wikipedia pages showing where HSUPA is deployed versus where HSDPA is deployed. Most of the target markets for the 3G only have UMTS/HSDPA and even the current CDMA providers in Canada only plan on implementing UMTS/HSDPA as a stepping stone for LTE. LTE is just around the corner so I would expect that the next iPhone will support LTE rather than bothering with HSUPA.
 
Comment

SpinThis!

macrumors 6502
Jan 30, 2007
467
104
Inside the Machine (Green Bay, WI)
Ack bandwidth is important but you don't need equal upstream to your downstream to send out acks. Maybe more like 10%.
Yeh—I would estimate even less than that. I have no problems getting the full 15 mbps out of my twc connection and my upload is only 1 mbps.

Some of those RFCs were written decades ago too when modems were state of the art. Along with fatter pipes also comes less problems with latency which I would wager is a bigger factor in internet speed. Fatter pipes + less latency + faster processors = less dropped packets = less ack packets.
 
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iPhoneNYC

macrumors 6502a
Nov 25, 2007
549
0
Remember, ATT is supposed to deliver tethering by the end of the summer. Then this would really come into play.
 
Comment

FoxyKaye

macrumors 68000
I dislike AT&T... but I *hate* Verizon. They are by far the most cooked and self-serving company in an industry of self-serving crooks.
You said it.

Then again, whenever my AT&T service drops a call, interjects static, interjects cross-talk from someone else's phone, won't find the network in my apartment, or simply gives me a network busy error when trying to dial out, I remember my days with Verizon fondly.
 
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