Qualcomm's New Snapdragon S4: MSM8960 & Krait Architecture Explored
by Brian Klug & Anand Lal Shimpi on October 7, 2011 12:35 PM EST- Posted in
- Smartphones
- Snapdragon
- Arm
- Qualcomm
- Krait
- MDP
- Mobile
- SoCs
MSM8960 Cellular Connectivity
Until now, to get 4G LTE connectivity in a smartphone has required using two basebands - one for delivering 4G LTE connectivity, and a more traditional smartphone-geared baseband for voice on 2G and 3G data. Take Verizon’s 4G LTE smartphone lineup for example, where many devices combine MSM8655 for camping a 1x voice session alongside MDM9600 for EVDO and LTE, or some other similar combination. Further, all those LTE basebands are built on 45nm process and really geared towards data specific applications.
For a while now we’ve also been talking about 28nm LTE basebands, and specifically the multimode connectivity on MSM8960. This is the first of Qualcomm’s S4 SoCs, and includes 4G LTE connectivity alongside the usual assortment of WCDMA/GSM/CDMA2000 standards. MSM8960’s cellular baseband is based around Qualcomm’s second generation (3GPP Rel.9) LTE modem, which is exactly what’s inside MDM9x15 which we’ve talked about in the past.
The full laundry list of what air interfaces MDM8960 supports is impressive - LTE FDD/TDD, UMTS, CDMA, TD-SCDMA (for Chinese markets), and GERAN (GSM/EDGE). I’ve made a small table below which gives the full laundry list.
| Snapdragon S4 - MSM8960 Cellular Support | |
| LTE FDD | 100 Mbps DL / 50 Mbps UL (Cat. 3, 3GPP Rel.9) |
| LTE TDD | 68 Mbps DL / 17 Mbps UL (Cat. 3, 3GPP Rel.9) |
| UMTS | DC-HSPA+ 42 Mbps DL (Cat. 24) / 11 Mbps UL (Cat. 8) |
| CDMA2000 | 1xAdvanced, EVDO Rev.B (14.7 Mbps DL / 5.4 Mbps UL) |
| GSM | GSM/GPRS/EDGE |
| TD-SCDMA | TD-SCDMA 4.2 Mbps DL / 2.2 Mbps UL |
What’s new again is inclusion of a category 3, 4G LTE baseband into the SoC alongside DC-HSPA+ and TD-SCDMA for the Chinese market. This is a substantial increase in the number of air interfaces supported onboard the SoC which will enable tighter integration and lower power from the baseband being manufactured on that same 28nm process. There’s still the requirement for external RF and transceiver (using RTR8600 or something similar) which houses all the analog, but that’s the same everywhere else.
Since the baseband in MSM8960 is shared with MDM9x15, the two are both 3GPP Release 9 devices, whereas presently MDM9600 and other launch LTE devices are 3GPP Release 8, which was the launch standard. This newer 3GPP release brings a number of improvements, and closer to transitioning to Voice over LTE (VoLTE) and SRVCC (single radio voice call continuity) for fallback to GSM/UMTS or 1x voice in the circumstance that 4G LTE coverage fades. The present combination of a camped 1x voice session alongside 4G LTE for data is also possible in MDM8960, which is exactly what’s done in the case of the HTC Thunderbolt.
In time, carriers will transition to using VoLTE and enrich the voice experience by offering services that work across the data session, alongside some circuit switched (CS) traditional 2G/3G voice to fall back to. For CDMA networks that’ll continue being the dual RF scenario which uses 1x for voice, and for UMTS networks that’ll be a SRVCC augmented fast handover to 3G for voice calls. This handover and call setup is targeted to take place in under one second.
There’s more to the connectivity situation as well, as MSM8960 includes built in WLAN 802.11b/g/n (single spatial stream), Bluetooth, and GPS. These are integrated directly into the MSM8960 the same way the cellular modem is and only require some external RF to use.
Of course, it’s one thing to talk about all this connectivity on MSM8960 and something else entirely to see it. With MSM8660, Qualcomm gave us one of their Mobile Development Platforms (MDPs) which is something of a reference design and development board for each SoC generation.
This time was no exception, and they showed off their new MSM8960 MDP connected to Verizon’s 4G LTE network streaming 1080p YouTube video, loading pages, and finally running a few speedtests using the Speedtest.net application.
This was all over Verizon’s 4G LTE network at Qualcomm HQ in San Diego and worked impressively well for hardware and software that still isn’t production level. In spite of marginal signal in the room we performed testing in, the MDP finished tests with pretty decent results. I ran some more tests on a Droid Bionic in the same room and saw similar results.
Final Words
Qualcomm has had MSM8960 silicon back in house for the past 3 months and is on-track for a release sometime in the first half of next year. Assuming Qualcomm can deliver on its claims, performance alone would be enough to sell this chip. Improved power characteristics and integrated LTE baseband really complete the package though.
The implications for a 1H 2012 MSM8960 release are tremendous. Android users will have to choose between a newer software platform (OMAP 4 running Ice Cream Sandwich) or much faster hardware (MSM8960). Windows Phone users may finally get a much needed performance boost if Microsoft chooses to standardize on Krait for its Windows Phone hardware refresh next year. End users will benefit as next year's smartphones and tablets will see, once again, a generational performance improvement over what's shipping today. LTE should also start to see much more widespread adoption (at the high end) as a result of Qualcomm's integrated LTE baseband.
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metafor - Friday, October 7, 2011 - link
Scorpion does support dual-channel, however, the 8x60 series does not have two controllers. The 8x55/7x30 does, however and in most cases, are used in the configuration you described in the article.ArunDemeure - Friday, October 7, 2011 - link
I knew MSM7x30/8x55 was dual-channel but I thought it was also available as a 64-bit LPDDR2 PoP solution? While it makes sense for most people to use it as single-channel LPDDR2 as opposed to dual-channel LPDDR1 these days, why would anyone ever have used both PoP and non-PoP DRAM at the same time? Maybe that old leaked presentation on Baidu listing all the MSM7x30/8x55 packages is wrong though.metafor - Friday, October 7, 2011 - link
A single Scorpion and Adreno 205 just didn't need both channels. It makes more sense for a lot of OEM's to use single 32-bit LPDDR2.ArunDemeure - Friday, October 7, 2011 - link
Hmm, that would certainly be news to me, it's possible but you'd still need a second memory controller and PHY so it makes very little sense. I can see a few possibilities:- The LPDDR2 and DDR2 subsystems aren't shared so in theory for tablets you could do 32-bit SiP LPDDR2+32-bit off-chip DDR2. Seems weird but not impossible.
- You can do 32-bit ISM+32-bit PoP. Once again, why do this? Were they limited by package pins with a 0.4mm pitch? Seems unlikely with a 14x14 package but who knows.
- You can genuinely do 32-bit PoP+32-bit on the PCB. Still seems really weird to me.
The MSM7200(A) had a separate small LPDDR1 chip (16-bit bus with SiP) reserved mostly for the baseband while the primary OS-accessible DRAM was off-chip. This was obviously rather expensive (fwiw Qualcomm only 'won' that generation on software and weak competition IMO) and removed it to reduce cost (making the chip's memory arbitrage more complex) on the MSM7227. I'm not sure about the QSD8650, maybe it still optionally had that extra memory bus (SiP-only) but it was more flexible and never used, it's hard to find that kind of info.
Cheers,
Arun
mythun.chandra - Friday, October 7, 2011 - link
Anand,Isn't this what I had pinged you about earlier?
z0mb13n3d - Friday, October 7, 2011 - link
I suggest you look into the facts before passing such statements.I don't know where you or the OP are getting your information from (3GHz A15's, quad 2.5GHz Kraits hitting next year, Kraits using HKMG etc.), but that's been pretty inaccurate. All you're doing is speculating based on bits and pieces floating around in PDF's and slides. I still remember one of his claims from the previous thread '2x A15's > 4xA9's' . While no one in their right sense of mind would argue that a the wider, deeper, single A15 is better than a single A9, to make such an uninformed, blanket statement (and to back it up with useless DMIPS numbers!) just doesn't bode very well.
ArunDemeure - Friday, October 7, 2011 - link
ST-Ericsson has publicly indicated the A9600's A15s can run at up to 2.5GHz, and GlobalFoundries has publicly said that the A9600 uses their 28nm SLP process which uses High-K but not SiGe strain. Is it really hard to believe a 28HPM or 28HP A15 could easily reach 3GHz? I'm not sure anyone will do that in the phone/tablet market, but remember ARM also wants A15 to target slightly larger Windows 8 notebooks and (I'm not as optimistic about this) servers.As for Krait, Qualcomm's initial PR mentioned 2.5GHz (not just random slides) and APQ8064 is on TSMC 28HPM which uses High-K. If you don't trust either me or metafor on that, Qualcomm has also publicly stated that most of their chips will run on SiON but that they were considering High-K for chips running at 2GHz or above: http://semimd.com/blog/2011/02/07/qualcomm-shies-a...
As for 2xA15 vs 4xA9, metafor's point is that most applications are still not sufficiently multithreaded. It has very little to do with DMIPS which is a worthless outdated benchmark (not that Coremark is perfect mind you - where oh where is my SPECInt for handhelds? Development platforms could support enough RAM to run it by now). Unlike him I think 4xA9 should be relatively competitive even if clearly inferior in some important cases, and as you imply it's a difficult and even fairly subjective topic, but I don't think metafor's opinion is unreasonable.
z0mb13n3d - Friday, October 7, 2011 - link
That is the point I'm trying to make! Semiconductor companies, by virtue of the fact that they have to sign OEM/ODM deals before they really even have working products almost always posture about how much their designs can go 'up to' or 'indicate' ratings and numbers. My beef with the earlier thread was that statements were being passed on as facts based purely on stuff posted in press releases. I can tell you, for a fact, that no 2.5GHz Krait (dual or quad) based product will be shipping in '12. I can also tell you for a fact that you will not see anything more than 1.8-2.2GHz (optimistic) in shipping A15's for mobile devices. I understand the A15 architecture is capable of much more, but to try and draw comparisons between a near-shipping mobile-spec quad-core A9 and an on-paper 3GHz A15 powering servers is not correct!If you did follow the previous thread closely, you will see that this was the only point I was trying to get across, in vain. No matter how you slice and dice it, the 2xA15 > 4xA9 argument is wrong. This is very similar to what we're seeing in the x86 market with Intel and AMD where the older, tri and quad core AMD's are still able to keep-up with or beat dual-core Intel's in threaded situations. Now it is an entirely different argument as to whether or not Google/MS/whoever else makes effective use of multi-core CPU's in their current mobile platforms and their relatively crude/simple kernels (as compared to desktop operating systems), but come Windows 8, I am willing to bet that quad core (or multi-core in general) SoC's will prove their worth.
ArunDemeure - Friday, October 7, 2011 - link
ST-E could underdeliver on the A9600, sure, but they've got a better process than OMAP5 and enough clever power saving tricks up their sleeve (some of which still aren't public) that I feel it's quite likely they won't. Remember 2.5GHz is only their peak frequency when a single core is on - they have not disclosed their throttling algorithms (which will certainly be more aggressive for everyone in the 28nm generation, especially on smartphone SKUs as opposed to tablets where higher TDPs are acceptable).Also multiple companies will be making A15s on 28HPM eventually. TSMC has indicated they have a lot of interest in HPM, and that should certainly clock at least 25% higher than GF's Gate-First Non-SiGe 28SLP. However the problem is that the A15 is quite power hungry, so I expect people will use that frequency headroom to undervolt and reduce power although a few might expose it with a TurboBoost-like mechanism. On the other hand, exposing the full 3GHz for Windows 8 on ARM mini-notebooks should be a breeze, and I don't see why you'd expect that to be a problem.
As for 2.5GHz Quad-Core Krait in 2012 - I think they're still on schedule for tablets in late 2012, but then again NVIDIA was still on schedule for tablets in August 2011 back in February, so it's impossible to predict these things. Delays happen, and it'd be foolish not to take metafor seriously simply because he is unable to predict the unpredictable.
Finally, 2xA15 vs 4xA9... metafor's point is that given the lower maturity of multithreading on handheld devices, it's more like high-end quad-core Intel CPUs beating eight-core AMD CPUs in the real world. As I said I'm not sure I agree, but it's fairly reasonable.
dagamer34 - Saturday, October 8, 2011 - link
I doubt it was a delay as much as nVidia being boastful. They've quite known for that.