I was going to post this yesterday, but analyzing Apple products on the day of Steve Jobs’ passing would have been silly. As the ITIF tribute said, Jobs is an irreplaceable man with an unparalleled talent for turning research ideas into accessible experiences for ordinary people, but as FCC Chairman Genachowski said, his example will inspire innovators for generations to come. There was nobody like him and never will be.

But life goes on, and it’s now time to explain what the new iPhone 4S is, what it isn’t, and how it got this way. There were an unusually large number of rumors on the tech blogs in advance of the launch, the most hilarious of which was the claim by Boy Genius Report that Apple would disclose that Sprint was going to get a six month exclusive on the iPhone 5 with LTE and the other carriers would be stuck with an inferior iPhone 4S. This didn’t happen, of course, and a few people are upset that there wasn’t an iPhone 5 launch this week. The most upset people in my acquaintance are older engineers who think about the networking experience in terms of bandwidth first and everything else second. Actually, we’ve moved on from that formulation:  It’s no longer the case that the configuration of the cellular network determines what you can and can’t do. Not only do we use our smartphones and tablet over Wi-Fi networks a great deal of the time, there are hundreds of thousands of mobile apps that work just fine over 3G and 3.5G networks; all the apps in the Apple store fit this description.

credit: iFixit

LTE is wonderful, of course, and it will stimulate a whole new generation of apps that go beyond the iconic Netflix experience that sets the standard for high-bandwidth mobile apps today. Netflix is more accurately a “nomadic” app that you enjoy while sitting down somewhere, one that doesn’t relate to your specific location, rather than a genuinely mobile app.

When it builds the iPhone 5 with LTE support, Apple will combine that function with the ability to fall back and to roam on 2G and 3G networks. All the big carriers need this capability, even Verizon, because none of them will have 100% LTE coverage anytime soon, and LTE still needs 2G and 3G networks for voice support (phone calls.) The current generation of LTE phones provide this by using two different cellular (“baseband”) chips, one for LTE and the other for 2G/3G. The trend is toward chips that combine the CDMA version of 2G/3G used by Verizon and Sprint with the GSM version supported by AT&T, T-Mobile, and the Europeans. The two chip configuration allows the phone vendor to offer a single world-wide unit that fully roamable. But it causes problems for phones like Apple’s that offer long battery life and slick design. The only phone that offers LTE with good battery life and nice design is the Motorola Droid Bionic, a CDMA-only (and Verizon-only) phone that’s considerably larger than the iPhone. This phone wouldn’t work for Sprint because they don’t have the native network coverage to support it, and they rely on WiMax rather than LTE for 4G support. Two baseband chips take a toll on battery life and to the size of the phone as well.The Bionic is an amazing phone, but it’s larger and heavier than the iPhone.

As Anand Shimpi explains, Motorola was able to build an elegant LTE phone by using the Qualcomm Snapdragon chip, which is not really an option for Apple:

The iPhone 4 PCB is already incredibly small, not leaving any room for an extra chip to enable LTE without shrinking the size of the battery (or increasing the thickness of the phone to accomodate both a larger PCB and a big battery). Today, Qualcomm is a leading provider of LTE baseband silicon and unfortunately they don’t ship any baseband hardware that supports both LTE and voice (over 1x/WCDMA) without extra silicon. In order to support both you need to be using something Qualcomm calls SoC Fusion. By leveraging a Qualcomm Snapdragon SoC in combination with Qualcomm’s MDM9600 LTE modem you can deliver both voice and LTE data. Otherwise the MDM9600 is only good for data, which is admittedly useful in things like USB modems or MiFis. Apple obviously doesn’t use Qualcomm Snapdragon SoCs so enabling LTE on the iPhone isn’t possible using Qualcomm baseband unless you make the phone’s PCB larger (which Apple obviously wasn’t going to do). Note that no one else seems to deliver a single chip LTE + 1x/WCDMA voice solution either, so this isn’t just a Qualcomm limitation.

Going LTE also means upgrading the phone’s processor, graphics, and infrastructure to do something meaningful with the data the LTE network provides, and this is the problem that the 4S addresses. Apple upgraded the CPU and the graphics processor and added support for the cloud-enabled “Siri personal assistant” feature that computer scientists have been dreaming about for decades, as you can see from this Apple video from 1987:

Siri is the software side of full LTE application enablement, so we can think of it as a necessary step toward the full use of LTE. It’s not really possible to build a phone right now that supports LTE and GSM in the way that you’d like. For that to happen, the chip companies (Intel and Qualcomm) need to produce a single “baseband” radio chip that combines LTE with 2G and 3G for both GSM and CDMA, and saves power to boot. The phone manufacturers need to write support software for this chip as well, and that’s no easy task, as Dean Bubley explains:

To sum up – in my view, the iPhone 4S is all about the hardware platform shift. Stuff like Siri is window-dressing in comparison, to give the fans at least something visible. LTE support was completely unrealistic (as I’ve said before) given the other more important and urgent changes going on with the platform. It’s also another reason why fripperies like NFC have been kicked further down the road – especially as I imagine Apple knows very well that it’s being overhyped.

[Note: I don’t agree with Dean on Siri, of course.] It’s going to be six months to a year before you can get an iPhone with LTE support unless you’re willing to get a mobile hotspot from Verizon, effectively a way to house that pesky LTE chip without increasing the size of the iPhone. It would be interesting to snap one of these into your car, possibly with the available external antenna, so you can enjoy the benefits of LTE without sacrificing the benefits of the iPhone. Aside from the $50/month LTE data charge, this isn’t a bad way to go while it’s all shaking out. (Verizon will let you buy LTE month-to-month if you pay full price for the MiFi.)

So the bottom line is that the only reasonable ways to offer LTE right now are either in a data-only device like a MiFi or in a handheld that uses the Qualcomm Snapdragon Fusion SoC/processor. Apple’s software won’t work on the Snapdragon Fusion SoC (“system on a chip,” a single chip combining CDMA with the CPU and related circuitry) without a major rewrite, so they’re probably hard at work on that task. It’s a good guess that they’re also hard at work rewriting their code to support the future Intel chip that combines GSM, CDMA, and LTE, but we won’t see said chip for a while. This points to Apple suffering, to a certain extent, from its success with the current set of iPhones. They now have a ton of applications to support, so they have to move carefully where their software platform is concerned.

I suspect they’ll pull off the transition quite well, but we’ll know more in June.