French startup tackles SoCs for emerging WiMAX market

Sequans Communications revealed plans for a MAC/PHY integrated baseband SoC at this past week's WiMAX Summit here. The upstart will join the WiMAX race that already included Intel Corp. and Fujitsu Microelectronics.

In an interview, Sequans Communications executives outlined its WiMAX SoC architecture, which they said will be designed to provide WiMAX customer premises equipment (CPE) for below $50 and less than $20 per link for WiMAX basestations by 2006. The company plans to introduce the industry's first WiMAX-certified MAC/PHY integrated FPGA platform by October, in time for a WiMAX industry plug fest.

The 22-employee fabless chip company, whose founders are mostly ex-Alcatel engineers, is promising two WiMAX SoCs in the second quarter in 2005, complete with modular software packages and reference designs " one for basestations and another for CPE.

While stressing its expertise in signal processing and cable modem chip development, George Karam, president and CEO of Sequans, said the startup's strengths in threee key areas would allow it to compete directly with Intel and Fujitsu. They are: optimal partitioning of hardware and software in its WiMAX SoC architecture; a portfolio of WiMAX technologies covering both MAC and PHY; and solutions for base and subscriber stations.

Besides Intel and Fujutsu, Wavesat Inc. is also scheduled to launch and integrated MAC/PHY SoC. Wavesat (Dorval, Quebec) will unveil a PHY-only WiMAX chip this fall, with plans for an integrated MAC/PHY SoC for the CPE market in 2005, according to Wavesat CEO Michel Guay.

For the basestation market, Wavesat will introduce a FPGA-based platform next year to provide the flexibility often required in basestation equipment.

A "mad dash in WiMAX chips has already begun," said Edward Rerisi, vice president of research at ABI Research (Oyster Bay, N.Y.). However, unlike the earlier Wi-Fi chip development fad, the number of companies involved in designing WiMAX silicon today is far smaller.

Rerisi said one reason is that venture capitalists were burned by failed investments in Wi-Fi chip startups. Further, the initial WiMAX market will be far smaller than Wi-Fi, he cautioned. Compared to the 80 million Wi-Fi chip sets forecast to be sold this year, WiMAX demand in 2006 will be "only a couple of hundred thousand subscribers," Rerisi projected.

Sequans' Karam said he anticipates an eventual delay in deliveries. Although some competitors' first working WiMAX chip samples are promised this fall, they will need more time to gain certification from the WiMAX Forum. More likely, most companies will have products by the second quarter of 2005, about when Sequans' own silicon arrives.

Sequans' WiMAX SoC architecture, based on 802.16 orthogonal frequency division multiplexing (OFDM), is billed as providing up to 75 Mbit/s throughput with superior RF performance and advanced MAC features, according to the company. Using a fully digital front-end, the chip provides both IF and baseband interfaces to accommodate different types of external RF chips. The PHY uses a very fast synchronization algorithm for simultaneous timing and frequency recovery, together with a proprietary block turbo-code decoding algorithm.

The biggest differentiator may be smart hardware and software partitioning in the SoC architecture, said Ambroise Popper, manager of product marketing at Sequans. The SoC integrates one hardware block handling PHY layers such as fast Fourier transfer and forward error correction. Another hardware block handles processing-intensive MAC features such as encryption/decryption and packet header parsing.

The remaining MAC features, such as scheduling, classification filtering and channel optimization, are processed in software running on a RISC core integrated on the SoC. Karam said Sequans likely will use either MIPS or ARM for its processor core.

The basestation SoC integrates two processor cores to handle more complex MAC functions. The SoC for CPE will use only one RISC core. Eighty percent of the algorithms used in PHY layers for basestations and CPE are the same, but completely different MAC layers must be developed for the two separate SoCs used in basestations and CPE. First-generation chips will be fabricated in a 0.13 micron process.

Sequans will provide modular software packages, which will run on top of its hardware's API. The company also said it will integrate as many features as possible to comply with the emerging 802.16e mobility spec.

Meanwhile, Intel remains a vocal promoter of WiMAX applications for laptops and PDAs. Randall Schwartz, strategic planning manager of Intel's Wireless Networking Group, told the summit here it is betting on a scenario in which 3G and WiMAX co-exist. "There is no one best technology. WiMAX fits in with 3G, as 3G is used primarily for voice and some data, while WiMAX primarily for data and some voice."