Faster Throughput on WCDMA

Fixing unintended attenuation is only one part of what’s new however, the other part of the story is faster cellular connectivity for users on WCDMA/UMTS carriers. Users who are using the 4S on CDMA (like Sprint or Verizon) won’t see a performance difference since this is still the same EVDO Rev.A.

The iPhone 4 used an Intel/Infineon X-Gold 618 which supported HSDPA 7.2 and HSUPA 5.76. The MDM6610 inside the 4S supports HSDPA 14.4 and HSUPA 5.76, alongside a number of 3GPP Rel.7 features which are colloquially known as HSPA+. I talked about this extensively in another piece when there was some confusion about whether or not the 4S is HSPA+ - which it is.

iPhone Cellular Speeds
Property iPhone 3G/3GS iPhone 4 (GSM/UMTS) iPhone 4 (CDMA) iPhone 4S
Baseband Infineon X-Gold 608 Infineon X-Gold 618 Qualcomm MDM6600 Qualcomm MDM6610
HSDPA Cat.8 - 7.2 Mbps Cat.8 - 7.2 Mbps N/A Cat.10 - 14.4 Mbps
HSUPA None - 384 Kbps WCDMA only Cat.6 - 5.76 Mbps N/A Cat.6 - 5.76 Mbps
EVDO N/A N/A 1x/EVDO Rev.A 1x/EVDO Rev.A

The previous X-Gold 618 baseband was a nice improvement over the iPhone 3G/3GS’ X-Gold 608, which lacked HSUPA, but in a world where most WCDMA carriers are at least running HSDPA 14.4, it’s nice to finally have an iPhone with something faster than HSDPA 7.2. I’ve done lots of testing inside my Tucson, AZ market (which is “4G” HSPA+ on AT&T’s coverage viewer) with both the 4 and the 4S, and have built a very good feel for the 4’s performance. As a reminder, if you’re in the USA, those dark blue areas represent HSPA+ coverage areas with AT&T’s upgraded backhaul. In practice these are at least HSDPA 14.4.

 
Left: iPhone 4 Limited to ~6.1 Mbps down, Right: iPhone 4S (same location) hitting ~9 Mbps

With line of sight to an AT&T NodeB inside my HSPA+ market I’m used to seeing a maximum downstream throughput on the iPhone 4 of almost exactly ~6.1 Mbps, which is about right for the 4’s HSDPA 7.2 maximum when you include overhead. The nice straight line in that result should clue you in that downstream throughput on the 4 was being gated by the baseband. On the 4S, in this same location, I’ve been able to get 9.9 Mbps when the cell isn’t loaded at night (I didn't grab a screenshot of that one, for some reason). It’s nice to finally not be gated by the baseband anymore on an iDevice. Having a faster baseband is part of the reason the 4S’s cellular performance is much better, the other half is receive diversity which helps the 4S push these high throughput rates, and also dramatically improve performance at cell edge.

I did some drive testing with the 4 and 4S side by side and targeted areas that I know have pretty poor signal strength. The 4S is shown in yellow, the 4 in blue.

You can see how downstream throughput gets a nice shift up, and the average changes as well, from 2.28 Mbps on the 4 to 2.72 Mbps on the 4S. The maximum in this sample increases from 6.25 to 7.62 Mbps as well. It isn’t a huge shift, but subjectively I’ve noticed the 4S going a lot faster in areas that previously were difficult for the 4.

We’ve also run the usual set of standalone tests on the 4S on AT&T in my market of Tucson, AZ, in Anand’s market of Raleigh, NC, and on Verizon in Raleigh, NC. Though we don’t have a Sprint 4S yet, we hope to do a more serious 4S carrier comparison here in the US when we get one. First up is AT&T which is of course HSPA+ in both of our testing markets.

AT&T HSPA+

Verizon EVDO

iPhone 4S Speedtest Comparison
Carrier AT&T Verizon
  Avg Max Min Avg Max Min
Downstream (Mbps) 3.53 9.94 0.24 0.82 2.05 0.07
Upstream (Mbps) 1.17 1.86 0.009 0.38 0.96 0.003
Latency (ms) 137 784 95 177 1383 104
Total Tests 457 150
Air Interface HSPA+
(HSDPA 14.4/HSUPA 5.76)
EVDO Rev.A

For the CDMA carriers, the 4S shouldn’t (and doesn’t) bring any huge improvement to data throughput because the CDMA 4 had both receive diversity and MDM66x0. For users on GSM/UMTS, however, the 4S does make a difference again thanks to the inclusion of those two new features.

One of the things I noticed was absent on the CDMA iPhone 4 was the 3G toggle. It does indeed make some sense to not include this in a CDMA 1x/EVDO scenario since power draw is about the same between the two air interfaces, however, the absence of this toggle has carried over to the 4S regardless of whether the phone is activated on a CDMA2000 or UMTS/GSM network. That’s right, you can go under Settings -> General -> Network, and there’s no longer any 3G Data toggle which you can disable and fall onto EDGE (2G) with now.

 
Left: iPhone 4S (no 3G toggle), Right: iPhone 4 (3G toggle)

It’s likely that this is absent to accommodate the multi-mode nature of the 4S (and thus the lowest common denominator CDMA mode), however the absence of this toggle makes getting connected in congested areas more difficult. In some markets, (I’m looking at you, AT&T in Las Vegas), EDGE is often the only way to get any connectivity, even without a major convention going on. Not having that 3G toggle makes manually selecting that less-used but more reliable connection impossible now, to say nothing of the potential battery savings that this would afford (and that we sadly can’t test now).

There’s one last tangential question about HSPA+ on the 4S, specifically on AT&T. I’ve left this to the end since it doesn’t impact non-US 4S users, but the last question is whether the 4S is actually on HSPA+. For a while, I was concerned that AT&T would continue using the wap.cingular APN on the 4S which seems shaped to around 7.2 Mbps HSDPA. I’m glad to report that AT&T hasn’t continued using wap.cingular on its 4S data plans, instead using “phone” which is a newer APN that allows for HSPA+ (above 7.2 Mbps) rates. You can check this yourself under PDP Context Info on the 4S in field test.

Improved Baseband - No Deathgrip The A5 Architecture & CPU Performance
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  • tipoo - Monday, October 31, 2011 - link

    Anyone know if there is a reason this hasn't made it into any Andriod phone yet? Does Google specify compatible GPU's, or is it cost, or development time, etc? Looks like it slaughters even the Mali 400 which is probably the next fastest. Reply
  • zorxd - Monday, October 31, 2011 - link

    The only reason is that no one used it yet. The TI OMAP 4470 will use the 544 which is probably a little faster.
    The SGS2 is using the slower Mali 400, however it was released 6 months ago. Yet it's not that bad, even beating the 4S in Glbenchmark pro.
    Reply
  • zorxd - Monday, October 31, 2011 - link

    I meant no SoC vendor is using it. Reply
  • djboxbaba - Monday, October 31, 2011 - link

    The numbers were incorrect and have been updated, the 4S is ~2x faster than the GS2 on the GLBenchmark Pro. Reply
  • freezer - Thursday, November 03, 2011 - link

    But not when running at phone's native resolution. Thats what people will use while running games on their phone.

    iPhone 4S has much more pixels for GPU to draw while having much smaller screen. Not very optimal for gaming right?

    http://glbenchmark.com/result.jsp?benchmark=glpro2...
    Reply
  • djboxbaba - Thursday, November 03, 2011 - link

    Correct, but we're comparing the GPU's by standardizing the resolution. Of course in the native resolution this will change. Reply
  • thunng8 - Monday, October 31, 2011 - link

    I don't see any GL benchmark that the Mail 400 beats the 4S??? Reply
  • freezer - Thursday, November 03, 2011 - link

    That's because Anandtech review shows only the 720p offscreen results.

    This gives very different numbers compared to running GL Benchmark Pro in phone's native resolution.

    iPhone 4S has about 60% more pixels than Galaxy S2, and so its GPU has to draw much more pixels in every frame.

    Go to glbenchmark.com and dig database yourself.
    Reply
  • Ryan Smith - Monday, October 31, 2011 - link

    The 544 should be identical to the 543 at the same clock and core configuration. It's effectively a 543 variant with full D3D feature level 9_3 support. The primary purpose of the 544 will be to build Windows devices, whereas for non-Windows devices the 543 would suffice. We don't have access to PowerVR's pricing, but it likely costs more due to the need to license additional technologies (e.g. DXTC) to achieve full 9_3 support. Reply
  • Penti - Tuesday, November 01, 2011 - link

    Who will use it to support Windows Phone though? Qualcomm uses their own AMD/ATi based Adreno GPU. I guess it will be TI's attempt off getting Microsoft to support Windows Phone on their SoC in order to supply say partners of theirs like Nokia. Or might just be a later purchase/contract date for the other SoC vendors. Getting the IP-blocks later, but many did opt for the Mali-400 so why wouldn't they opt for the successor too? It seems to have worked out good. Samsung is just one of the vendors that usually did use PowerVR. I guess ST-E will use it in order to support Windows Phone on Nova A9540 SoC too. While Android vendors might opt for the older A9500 still.

    Interesting to see how Nvidia do lag in this field though.
    Reply

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