Electronic Design

Chip Makers Target LTE

With backing from nearly all of the leading cellular-service providers in the world, Long-Term Evolution (LTE) is clearly the 4G technology of choice for mobile data. Both Verizon and NTT plan to initiate LTE service late this year, with other major carriers following over the next few years.

Due to the high cost and short battery life of initial LTE devices, shipments will be small to start, reaching perhaps 10 million units in 2011. Even in 2014, LTE will still constitute less than 10% of cellular-baseband shipments. As the cost drops and capabilities of LTE devices improve, however, shipments should exceed those of 3G devices by 2019.

Some handset makers are developing their own LTE ASICs, but most LTE devices will use standard baseband processors from the leading chip suppliers. Chip makers don’t want to be left behind in the 4G transition. In the early days of UMTS (3G), Qualcomm was the only independent chip supplier. Seven years later, the company continues to supply 58% of standard baseband processors for UMTS/HSPA. The LTE market should be more competitive.

ST-Ericsson is developing a full-featured LTE modem chip, the M700, that supports all channel widths up to 20 MHz as well as MIMO and receive diversity. The chip’s throughput is limited to 100 Mbits/s downstream and 50 Mbits/s upstream (Category 3), which is still far more than current HSPA devices.

Qualcomm is also investing heavily in LTE. Leveraging its existing HSPA technology, the company is developing the MDM9200, a Category 2 LTE device that lacks MIMO and is rated at half the throughput of the M700. Unlike the M700, however, the Qualcomm chip integrates prior-generation HSPA, UMTS, and EDGE modems. Due to the limited initial deployments of LTE, backward compatibility with older networks is crucial. Qualcomm even offers a version with CDMA compatibility, which Verizon plans to use.

As its name implies, Infineon’s SDR20 employs software-defined radio (SDR) technology. Programmable DSP cores demodulate and decode LTE signals. The DSPs can also be programmed for HSPA, EDGE, and other protocols, providing excellent backward compatibilty. The performance of the DSP engines, though, limits the chip to just 25 Mbits/s of throughput.

Infineon isn’t alone, as other vendors turn to SDR for LTE products. Altair, for example, announced the FourGee-3100 as a Category 3 LTE device with full MIMO support. Altair’s SDR technology, based on a proprietary signal-processing engine, was originally developed for WiMAX. Other WiMAX chip startups are also eyeing the LTE market.

Most of the initial LTE devices lack the multimedia capabilities required in high-end handsets. So instead they target USB modems, which are likely to be the most common LTE devices for the first few years. To build a 4G smart phone, these chips can be coupled with an external application processor.

Initial LTE chip production is slated for the latter half of next year. Given the preliminary state of LTE technology, these schedules are highly susceptible to change.

Other vendors have announced their work on LTE, but not specific products. These companies include Broadcom, Freescale (which has since put its LTE technology up for sale), Icera, and Marvell. By 2012, most baseband-chip vendors will be at least sampling LTE products. The race is on.

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