Qualcomm's lock on LTE, or why we don't have quad-core LTE devices yet
By Dan Seifert
There were two big features that many device manufacturers were pushing hard this year at Mobile World Congress: quad-core processors and 4G LTE connectivity. However, we never saw those two features together on the same device, with the most notable example being the HTC One X, where the HSPA+ version for global markets sports NVIDIA's Tegra 3 quad-core processor, while the LTE version headed to AT&T in the States makes do with a dual-core Qualcomm chip. We went digging for more info as to why this was the case.
To start with, let's explain how the processor and cellular modem work on a mobile device. The processor, which does the heavy lifting and makes your smartphone do all of these wonderful things that we love so much, can be considered the brain of the phone. It can be accompanied by other components, such as graphics processing chips, but for the sake of simplicity, we are only going to look at the actual processor here. There are three major processor manufacturers that smartphone makers can source their chips from: Qualcomm, Texas Instruments (TI), and NVIDIA. Some manufacturers choose to use designs of their own, such as Apple with its A4 and A5, Samsung with its Exynos line, and now even Huawei with its new quad-core processor, and there are other manufacturers out there, such as Marvell, but the vast majority of device makers choose a processor made by these three for their high-end smartphones and tablets.
At the moment, only NVIDIA's quad-core Tegra 3 is shipping in quantity to manufacturers. Qualcomm is still preparing its new quad-core processors, and TI is focusing on next-gen dual-core technology chips.
While the processor is the brain of your smartphone, we can think of the cellular modem as the eyes, ears, and mouth of the device. It allows your smartphone to communicate back and forth with cellular networks and lets you access the internet, make phone calls, and send endless SMS messages while you are out and about. Cellular modems have a variety of specifications, but the ones that we see most often today support HSPA+( INFO) networks, LTE( INFO) networks, or CDMA( INFO) networks.
Some cellular modems have support for multiple types of networks at the same time, while some smartphone manufacturers include multiple modems in one device. Manufacturers of cellular modems include Qualcomm, Renesas, and ST Ericsson, among others, and certain phone manufacturers, like Motorola, also build their own custom cellular modems for their own devices, but don't offer them to competing manufacturers.
At the moment, Qualcomm is the only cellular modem manufacturer that has an LTE compatible modem that is designed for use in consumer devices - and it is integrated into its processor chipsets.
When a manufacturer designs a new smartphone, it compiles a number of components from outside manufacturers so that the device is feature complete, including a processor and cellular modem. So, at this point, you are probably asking yourself, why can't HTC just grab an LTE modem and stick it next to the NVIDIA quad-core processor, making everyone giddy with excitement in the process?
The answer is that not all modems and processors are compatible with each other, and that there are only a limited number of LTE modems available to use. Herein lies the rub, and the crux of the reason why we don't have quad-core LTE devices just yet: Qualcomm is the only manufacturer of easily-sourced LTE modems and its modems are only compatible with its own processors. Qualcomm chipsets, as they are commonly referred to, come as complete package, with the modem and processor bundled together. A manufacturer cannot use a TI, NVIDIA, or any other processor with a Qualcomm modem at this time.
I spoke to both NVIDIA and HTC to get their take on this matter. NVIDIA develops its processors to be compatible with most any modem on the market - a "plug-and-play" design. Manufacturers can pair an NVIDIA processor with an LTE, HSPA+, or CDMA modem - provided the modem they want is available when they are producing their device. NVIDIA knows that the Tegra 3 cannot be used with Qualcomm's LTE modem, so it has garnered support from companies like ST Ericsson, Renesas, and GCT Semiconductor to develop LTE modems that can be used with its plug-and-play architecture. NVIDIA also has its line of Icera modems that will eventually support LTE, though it is not saying when it expects them to be available.
Unfortunately for us, it will be some time before any of these modems are available for manufacturers to use, so that is why we didn't see any Tegra 3 devices with LTE support at Mobile World Congress this year except for a one-off device made by Fujitsu for the Japanese market (Fujitsu designed its own LTE modem to work with the Tegra 3). Motorola has built its own LTE modems already - they are used in all of its current LTE devices - but the company was a no-show at Mobile World Congress and didn't announce anything with a Tegra 3 processor inside.
When I asked HTC specifically as to why it used a dual-core modem in the LTE version of the One X smartphone, chief product manager Kouji Kodera said that for the markets where the LTE version of the One X is headed (read: the U.S.), LTE connectivity was much more important than anything else, and basic HSPA+ just would not do. In order to deliver the One X in a timely manner, it had to use a dual-core Qualcomm processor to have LTE connectivity in the device, since it cannot build its own cellular modems from scratch. For those that are concerned about performance with the dual-core chip, Kodera said that HTC did not see an appreciable difference in performance between the Qualcomm Snapdragon S4 processor and the quad-core NVIDIA Tegra 3 processor when it was designing the device. It should be noted, though, that the Tegra 3 version will have access to certain high-end games, while the dual-core version will not.
HTC wasn't the only one stuck in this position at MWC: both LG and ASUS announced new LTE devices with dual-core processors next to devices with NVIDIA's Tegra 3 quad-core processor and HSPA+ connectivity. LG's new flagship, the Optimus 4X HD, has a Tegra 3, but lacks LTE, while the Tegra 3-equipped versions of ASUS's Transfomer line of tablets also lack LTE connectivity.
Qualcomm was indeed demoing new quad-core processors at Mobile World Congress, but it did not say when we would see these in devices. These new quad-core processors are sure to be compatible with Qualcomm's LTE modems. TI also has quad-core on its radar, but its main focus right now is on its ARM A15-based OMAP5 dual-core processors, which purportedly offer better performance than NVIDIA's quad-core Tegra 3 (for more on this, check out Michael's excellent write-up on it from earlier this week).
LTE will be headed to quad-core devices in the future - there is no doubt about that. The work being done by ST Ericsson, Renesas, and GCT Semiconductor, along with the Icera team over at NVIDIA, will hopefully put more LTE modems on the market before long. And eventually Qualcomm will release its own quad-core processors that use its LTE modems. But, for now, if you want to get your quad-core fix, you will have to make do with something less than LTE connectivity.
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