Electronic Design

Commercial WiMAX Silicon Hastens Broadband Wireless

WiMAX is the commercial name for equipment that meets the IEEE's 802.16 standard for wireless broadband. With the standard now in place, lots of development activity now targets the equipment and services for this forthcoming broadband alternative. It promises high-speed Internet access to rural and small-town folks who otherwise would have no options.

The latest baseband chip from Fujitsu should accelerate product development in this growing sector. The MB87M3400 system-on-a-chip (SoC) media-access controller (MAC) and physical layer (PHY) complies with the IEEE 802.16-2004 standard. It can be used in basestations or customer-premise equipment like set-top boxes. The SoC also works with existing RF chips and circuits in the 2.5-, 3.5-, and 5.8-GHz bands, such as those available from RF Integration.

The I and Q analog signals to and from the RF chips go to on-board analog-to-digital and digital-to-analog converters for receive and transmit operations, respectively (see the figure). Typical features include adaptive modulation schemes like BPSK, QPSK, 16QAM, 64QAM, and 256QAM.

The chip supports all available channel bandwidths from 1.75 to 20 MHz. When using 64QAM with all 192 OFDM subcarriers, it can hit a 100-Mbit/s raw data rate. Support is included for the uplink subchannelization defined in the standard. The chip can be configured to handle FDD or TDD applications. Also incorporated is full on-chip security with DES/3DES or AES/CCM encryption/decryption.

At the heart of the chip lies an ARM926 RISC processor. It implements the 802.16 upper-layer MAC, scheduler, drivers, and protocol stacks, as well as any special user application software. An on-chip ARC Tangent RISC processor handles all DSP functions, the lower-layer MAC functions, and the offloaded processing from the upper-layer MAC. Some available interfaces include Ethernet, RS-232C, SPI, I2C, and GPIO. An integrated memory controller and DMA are included as well.

Housed in a 436-pin BGA, the chip costs $125 in sample quantities. A complete reference design, evaluation boards, and software are available, too.

The WiMAX chip sells for $45 in 1K quantities.



WiMAX Forum

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