PARIS—Advancements of LTE technology, including LTE Advanced and LTE Advanced Pro, are creating havoc. They are spawning a host of new demands that make the next-gen baseband designs far more complex than any of the previous smartphone modems.
The world’s leading telecom chip vendor Qualcomm, CEVA, a DSP core supplier, and ARM, a processor core company, are all racing to meet that challenge. They have developed new processor architectures, which they are unveiling in prior to the Mobile World Congress next week. Qualcomm announced Snapdragon X16 last week, while CEVA this week revealed CEVA-X4 and ARM is now talking up its new Cortex-R8. Qualcomm is running intensive LTE protocols and voice codecs on its Hexagon DSP core in the new modem, while using ARM Cortex to run the Linux OS, IMS and IP stacks.
So, what are so different about these new baseband modems?
At issues are: increased carrier aggregation, merging multi-radio access technology into one-single modem, low-latency operations necessary when switching from one modem to another, handling dual cells simultaneously and complexity that comes with Voice over LTE, among other things. A new baseband modem must be able to handle all of them and more, according to CEVA.
Mike Demler, senior analyst, The Linley Group, called for “a comprehensive overhaul” in existing modem architectures, “in order to meet the increasingly stringent performance and power constraints” of LTE Advanced and LTE Advanced Pro.
The three-way race among Qualcomm, CEVA and ARM is morphing into a competition for new processing cores, hardware acceleration and DSPs.
Vendors are discussing how best the increased LTE baseband workloads – in Layer 1 PHY controller, Layer 2 and Layer 3 processing – should be handled; and whether that should be done via advanced DSP cores, beefed-up processor cores or the combination of the two.
Each vendor, with different turfs to defend, obviously has different ideas.
Qualcomm last week revealed its advanced LTE modem, Snapdragon X16, designed to support Advanced (LTE-A) Pro Category 16 downlink speeds of up to 1 Gbps and Category 13 uplink speeds of 150 Mbps capable of supporting Gigabit LTE.
Not to be outdone by Qualcomm, both CEVA and ARM are revealing their own newly designed cores – CEVA-X4 and ARM Cortex-R8 respectively – whose architectures, they said, are ready to meet the challenges of the LTE-Advanced Pro modems. No commercial baseband chips using either IP vendor’s processor core are available at this time.
The two IP core vendors have a clearly different focus in meeting with the increased processing needs of LTE Advanced Pro modem. CEVA, for example, is revamping its L1 PHY controller with CEVA-X4. ARM, in contrast, is focused on handling the increased demand for Layer 2 and L3 software processing through its newly designed quad-core Cortex-R8.
Linley Group’s Demler made it clear that Cortex-R8 and Ceva-X4 are two different animals. CEVA-X4 is for PHY-layer control, while ARM Cortex-R is not. “The X4 and R8 could co-exist in a modem application, with the X4 handling PHY and the Cortex-R handling higher-level control functions,” he said.
After examining the newly advanced baseband modem requirements in detail, “We’ve identified PHY controller as the bottleneck [in the next-generation baseband],” said Eran Briman, CEVA’s vice president responsible for marketing and corporate development.
Next page: Defending L2/L3 processing space