Wireless Systems Design

OFDM Building Blocks Help Speed WiMAX Development

To accelerate the evolution of IEEE 802.16 or WiMAX networks, the industry may turn to devices that already have the flexibility to support this emerging standard. For example, picoChip recently developed a WiMAX PHY library that will run on its picoArray processor. The company already has a number of OFDM building blocks. Now, this development integrates them to deliver an end-to-end solution. As a result, OEMs can accelerate the development of WiMAX-certified systems.

The library complements the company's reference designs for W-CDMA and HSDPA. In addition, the picoArray architecture helps to "future-proof" existing designs. After all, the IEEE 802.16 standard is already evolving toward more complex revisions. The company claims that key manufacturers are already using its picoArrays in 3G- and WiMAX-type base stations. It hopes that the availability of this library will accelerate the development and deployment of WiMAX-compliant systems.

The picoArray has the flexibility to address evolving standards or the introduction of new features. It can be used to implement IEEE 802.16d (next-generation fixed), 802.16e (mobility), or HPI (the Korean broadband-wireless standard). It also enables the efficient use of multiple antennas at high sample rates—a feature that is critically important for advanced algorithms like adaptive antennas, space-time-coding (STC), and MIMO. The system is suited for base stations as well as high-end subscriber stations.

The picoArray claims to deliver improvements in price, performance, and development time. It combines the price and programmability of a traditional DSP with the performance of an FPGA/ASIC. At 160 MHz and 4 W, the picoChip PC102 delivers performance of 200 GIPS. At that performance level, the company says that it can sustain 40 giga multiply accumulates per second (the standard benchmark of DSP performance). That number is approximately 10 times more than a top-of-the-line DSP.

A realistic 20-Msample/s, 256-point, complex Fast Fourier Transform (FFT) would take less than 5% of the PC102's capability. Similarly, a 100-tap FIR digital filter (say a 10-MHz channel with oversampling) might completely fill a normal DSP or require an FPGA. But it uses less than 5% of one picoArray. For error-correction functions (Reed-Solomon + Viterbi), a single PC102 device can easily decode sustained data rates of less than 100 Mbps with ample extra capability.

The company claims that its WiMAX chip—the PC8520—will meet the requirements of IEEE 802.15d. The PC8520 will be available in the third quarter of this year.

picoChip, Inc.
One Embarcadero Center, Suite 500, San Francisco, CA 94111; (415) 646-8910, FAX: (415) 366-3352, www.picochip.com.

TAGS: Digital ICs
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